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Sample records for relay selection generalizations

  1. Opportunistic Relay Selection With Limited Feedback

    KAUST Repository

    Eltayeb, Mohammed E.; Elkhalil, Khalil; Bahrami, Hamid Reza; Al-Naffouri, Tareq Y.

    2015-01-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Generally, relay selection algorithms require channel state information (CSI) feedback from all cooperating relays to make a selection decision

  2. Partial relay selection based on shadowing side information over generalized composite fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2011-11-01

    In this paper, in contrast to the relay selection protocols available in the literature, we propose a partial relay selection protocol utilizing only the shadowing side information of the relays instead of their full channel side information in order to select a relay in a dual-hop relaying system through the available limited feedback channels and power budget. We then presented an exact unified performance expression combining the average bit error probability, ergodic capacity, and moments-generating function of the proposed partial relay selection over generalized fading channels. Referring to the unified performance expression introduced in [1], we explicitly offer a generic unified performance expression that can be easily calculated and that is applicable to a wide variety of fading scenarios. Finally, as an illustration of the mathematical formalism, some numerical and simulation results are generated for an extended generalized-K fading environment, and these numerical and simulation results are shown to be in perfect agreement. © 2011 IEEE.

  3. Relay Selection with Limited and Noisy Feedback

    KAUST Repository

    Eltayeb, Mohammed E.; Elkhalil, Khalil; Mas'ud, Abdullahi Abubakar; Al-Naffouri, Tareq Y.

    2016-01-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Nonetheless, relay selection algorithms generally require error-free channel state information (CSI) from all cooperating relays. Practically, CSI

  4. Relay Selection with Limited and Noisy Feedback

    KAUST Repository

    Eltayeb, Mohammed E.

    2016-01-28

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Nonetheless, relay selection algorithms generally require error-free channel state information (CSI) from all cooperating relays. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we propose a relay selection algorithm that tackles the above challenges. Instead of allocating each relay a dedicated channel for feedback, all relays share a pool of feedback channels. Following that, each relay feeds back its identity only if its effective channel (source-relay-destination) exceeds a threshold. After deriving closed-form expressions for the feedback load and the achievable rate, we show that the proposed algorithm drastically reduces the feedback overhead and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback from all relays. © 2015 IEEE.

  5. Opportunistic Relay Selection With Limited Feedback

    KAUST Repository

    Eltayeb, Mohammed E.

    2015-08-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Generally, relay selection algorithms require channel state information (CSI) feedback from all cooperating relays to make a selection decision. This requirement poses two important challenges, which are often neglected in the literature. Firstly, the fed back channel information is usually corrupted by additive noise. Secondly, CSI feedback generates a great deal of feedback overhead (air-time) that could result in significant performance hits. In this paper, we propose a compressive sensing (CS) based relay selection algorithm that reduces the feedback overhead of relay networks under the assumption of noisy feedback channels. The proposed algorithm exploits CS to first obtain the identity of a set of relays with favorable channel conditions. Following that, the CSI of the identified relays is estimated using least squares estimation without any additional feedback. Both single and multiple relay selection cases are considered. After deriving closed-form expressions for the asymptotic end-to-end SNR at the destination and the feedback load for different relaying protocols, we show that CS-based selection drastically reduces the feedback load and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback. © 1972-2012 IEEE.

  6. Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

    KAUST Repository

    Sungjoon Park,

    2011-11-01

    In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula for opportunistic relaying in the channel, and validate the results by comparing it with the exact outage probability. Also, we suggest a new relay selection algorithm that incorporates shadowing. We consider a protocol of broadcasting the channel gain of the previously selected relay. This saves resources in slow fading channel by reducing collisions in relay selection. We further investigate the optimal relay selection period to maximize the throughput while avoiding selection overhead. © 2011 IEEE.

  7. Opportunistic Relay Selection in Multicast Relay Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil

    2014-12-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. However, for relay selection algorithms to make a selection decision, channel state information (CSI) from all cooperating relays is usually required at a central node. This requirement poses two important challenges. Firstly, CSI acquisition generates a great deal of feedback overhead (air-time) that could result in significant transmission delays. Secondly, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we introduce a limited feedback relay selection algorithm for a multicast relay network. The proposed algorithm exploits the theory of compressive sensing to first obtain the identity of the “strong” relays with limited feedback. Following that, the CSI of the selected relays is estimated using linear minimum mean square error estimation. To minimize the effect of noise on the fed back CSI, we introduce a back-off strategy that optimally backs-off on the noisy estimated CSI. For a fixed group size, we provide closed form expressions for the scaling law of the maximum equivalent SNR for both Decode and Forward (DF) and Amplify and Forward (AF) cases. Numerical results show that the proposed algorithm drastically reduces the feedback air-time and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback channels.

  8. Relay Selection for Cooperative Relaying in Wireless Energy Harvesting Networks

    Science.gov (United States)

    Zhu, Kaiyan; Wang, Fei; Li, Songsong; Jiang, Fengjiao; Cao, Lijie

    2018-01-01

    Energy harvesting from the surroundings is a promising solution to provide energy supply and extend the life of wireless sensor networks. Recently, energy harvesting has been shown as an attractive solution to prolong the operation of cooperative networks. In this paper, we propose a relay selection scheme to optimize the amplify-and-forward (AF) cooperative transmission in wireless energy harvesting cooperative networks. The harvesting energy and channel conditions are considered to select the optimal relay as cooperative relay to minimize the outage probability of the system. Simulation results show that our proposed relay selection scheme achieves better outage performance than other strategies.

  9. Relay selection from an effective capacity perspective

    KAUST Repository

    Yang, Yuli; Ma, Hao; Aï ssa, Sonia

    2013-01-01

    proposed scheme in certain scenarios. Moreover, the analysis presented herein offers a convenient tool to the relaying transmission design, specifically on which relay selection scheme should be used as well as how to choose the receiving strategy between

  10. Generalized instantly decodable network coding for relay-assisted networks

    KAUST Repository

    Elmahdy, Adel M.

    2013-09-01

    In this paper, we investigate the problem of minimizing the frame completion delay for Instantly Decodable Network Coding (IDNC) in relay-assisted wireless multicast networks. We first propose a packet recovery algorithm in the single relay topology which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate coding combinations that are at least as efficient as strict IDNC in reducing the average completion delay. We then extend our study to the multiple relay topology and propose a joint generalized IDNC and relay selection algorithm. This proposed algorithm benefits from the reception diversity of the multiple relays to further reduce the average completion delay in the network. Simulation results show that our proposed solutions achieve much better performance compared to previous solutions in the literature. © 2013 IEEE.

  11. Reactive relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-06-01

    Best relay selection is a bandwidth efficient technique for multiple relay environments without compromising the system performance. The problem of relay selection is more challenging in underlay cognitive networks due to strict interference constraints to the primary users. Generally, relay selection is done on the basis of maximum end-to-end signal to noise ratio (SNR). However, it requires large amounts of channel state information (CSI) at different network nodes. In this paper, we present and analyze a reactive relay selection scheme in underlay cognitive networks where the relays are operating with fixed gains near a primary user. The system model minimizes the amount of CSI required at different nodes and the destination selects the best relay on the basis of maximum relay to destination SNR. We derive close form expressions for the received SNR statistics, outage probability, bit error probability and average channel capacity of the system. Simulation results are also presented to confirm the validity of the derived expressions. © 2012 IEEE.

  12. Reactive relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz; Alouini, Mohamed-Slim; Qaraqe, Khalid A.; Hasna, Mazen Omar

    2012-01-01

    Best relay selection is a bandwidth efficient technique for multiple relay environments without compromising the system performance. The problem of relay selection is more challenging in underlay cognitive networks due to strict interference

  13. Opportunistic Relay Selection with Cooperative Macro Diversity

    Directory of Open Access Journals (Sweden)

    Yu Chia-Hao

    2010-01-01

    Full Text Available We apply a fully opportunistic relay selection scheme to study cooperative diversity in a semianalytical manner. In our framework, idle Mobile Stations (MSs are capable of being used as Relay Stations (RSs and no relaying is required if the direct path is strong. Our relay selection scheme is fully selection based: either the direct path or one of the relaying paths is selected. Macro diversity, which is often ignored in analytical works, is taken into account together with micro diversity by using a complete channel model that includes both shadow fading and fast fading effects. The stochastic geometry of the network is taken into account by having a random number of randomly located MSs. The outage probability analysis of the selection differs from the case where only fast fading is considered. Under our framework, distribution of the received power is formulated using different Channel State Information (CSI assumptions to simulate both optimistic and practical environments. The results show that the relay selection gain can be significant given a suitable amount of candidate RSs. Also, while relay selection according to incomplete CSI is diversity suboptimal compared to relay selection based on full CSI, the loss in average throughput is not too significant. This is a consequence of the dominance of geometry over fast fading.

  14. Outage performance of two-way DF relaying systems with a new relay selection metric

    KAUST Repository

    Hyadi, Amal; Benjillali, Mustapha; Alouini, Mohamed-Slim

    2012-01-01

    This paper investigates a new constrained relay selection scheme for two-way relaying systems where two end terminals communicate simultaneously via a relay. The introduced technique is based on the maximization of the weighted sum rate of both

  15. A genetic algorithm for multiple relay selection in two-way relaying cognitive radio networks

    KAUST Repository

    Alsharoa, Ahmad M.; Ghazzai, Hakim; Alouini, Mohamed-Slim

    2013-01-01

    In this paper, we investigate a multiple relay selection scheme for two-way relaying cognitive radio networks where primary users and secondary users operate on the same frequency band. More specifically, cooperative relays using Amplifyand- Forward

  16. Decode and Zero-Forcing Forward Relaying with Relay Selection in Cognitive Radio Systems

    KAUST Repository

    Park, Kihong; Alouini, Mohamed-Slim

    2014-01-01

    In this paper, we investigate a cognitive radio (CR) relay network with multiple relay nodes that help forwarding the signal of CR users. Best relay selection is considered to take advantage of its low complexity of implementation. When the primary

  17. Relay Selection and Resource Allocation in One-Way and Two-Way Cognitive Relay Networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-01-01

    In this work, the problem of relay selection and resource power allocation in one- way and two-way cognitive relay networks using half duplex channels with different relaying protocols is investigated. Optimization problems for both single

  18. Outage performance of two-way DF relaying systems with a new relay selection metric

    KAUST Repository

    Hyadi, Amal

    2012-04-01

    This paper investigates a new constrained relay selection scheme for two-way relaying systems where two end terminals communicate simultaneously via a relay. The introduced technique is based on the maximization of the weighted sum rate of both users. To evaluate the performance of the proposed system, the outage probability is derived in a general case (where an arbitrary channel is considered), and then over independently but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. The analytical results are verified through simulations. © 2012 IEEE.

  19. Full-Duplex Relay Selection in Cognitive Underlay Networks

    KAUST Repository

    Khafagy, Mohammad Galal; Alouini, Mohamed-Slim; Aissa, Sonia

    2017-01-01

    In this work, we analyze the performance of full-duplex relay selection (FDRS) in spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay(s), thereby

  20. Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

    KAUST Repository

    Sungjoon Park,; Stark, Wayne E.

    2011-01-01

    In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula

  1. Relay selection from an effective capacity perspective

    KAUST Repository

    Yang, Yuli

    2013-09-01

    In this work, we consider a cooperative network where multiple relay nodes having different modulation capabilities assist the end-to-end communication between a source and its destination. Firstly, we evaluate the effective capacity (EC) performance of the network under study. According to the analysis, an EC-based relay selection criterion is proposed. Based on the proposed selection rule and half-duplex decode-and-forward protocol, the activated relays cooperatively help with the packet transmission from the source. At the destination, packet combining is taken into account to improve the quality of service. Compared to the popular scheme, opportunistic relay selection, numerical results are provided to prove the validity and advantages of our proposed scheme in certain scenarios. Moreover, the analysis presented herein offers a convenient tool to the relaying transmission design, specifically on which relay selection scheme should be used as well as how to choose the receiving strategy between with and without packet combining at the destination. © 2013 IEEE.

  2. Threshold-Based Relay Selection for Detect-and-Forward Relaying in Cooperative Wireless Networks

    Directory of Open Access Journals (Sweden)

    Fan Yijia

    2010-01-01

    Full Text Available This paper studies two-hop cooperative demodulate-and-forward relaying using multiple relays in wireless networks. A threshold based relay selection scheme is considered, in which the reliable relays are determined by comparing source-relay SNR to a threshold, and one of the reliable relays is selected by the destination based on relay-destination SNR. The exact bit error rate of this scheme is derived, and a simple threshold function is proposed. It is shown that the network achieves full diversity order ( under the proposed threshold, where is the number of relays in the network. Unlike some other full diversity achieving protocols in the literature, the requirement that the instantaneous/average SNRs of the source-relay links be known at the destination is eliminated using the appropriate SNR threshold.

  3. Buffer-Aided Relaying with Adaptive Link Selection

    DEFF Research Database (Denmark)

    Zlatanov, Nikola; Schober, Robert; Popovski, Petar

    2013-01-01

    In this paper, we consider a simple network consisting of a source, a half-duplex decode-and-forward relay, and a destination. We propose a new relaying protocol employing adaptive link selection, i.e., in any given time slot, based on the channel state information of the source-relay and the relay......-destination link a decision is made whether the source or the relay transmits. In order to avoid data loss at the relay, adaptive link selection requires the relay to be equipped with a buffer such that data can be queued until the relay-destination link is selected for transmission. We study both delay......-constrained and delay-unconstrained transmission. For the delay-unconstrained case, we characterize the optimal link selection policy, derive the corresponding throughput, and develop an optimal power allocation scheme. For the delay-constrained case, we propose to starve the buffer of the relay by choosing...

  4. Relay Selection and Resource Allocation in One-Way and Two-Way Cognitive Relay Networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-05-08

    In this work, the problem of relay selection and resource power allocation in one- way and two-way cognitive relay networks using half duplex channels with different relaying protocols is investigated. Optimization problems for both single and multiple relay selection that maximize the sum rate of the secondary network without degrading the quality of service of the primary network by respecting a tolerated interference threshold were formulated. Single relay selection and optimal power allocation for two-way relaying cognitive radio networks using decode-and-forward and amplify-and-forward protocols were studied. Dual decomposition and subgradient methods were used to find the optimal power allocation. The transmission process to exchange two different messages between two transceivers for two-way relaying technique takes place in two time slots. In the first slot, the transceivers transmit their signals simultaneously to the relay. Then, during the second slot the relay broadcasts its signal to the terminals. Moreover, improvement of both spectral and energy efficiency can be achieved compared with the one-way relaying technique. As an extension, a multiple relay selection for both one-way and two-way relaying under cognitive radio scenario using amplify-and-forward were discussed. A strong optimization tool based on genetic and iterative algorithms was employed to solve the 
formulated optimization problems for both single and multiple relay selection, where discrete relay power levels were considered. Simulation results show that the practical and low-complexity heuristic approaches achieve almost the same performance of the optimal relay selection schemes either with discrete or continuous power distributions while providing a considerable saving in terms of computational complexity.

  5. Generalized routing protocols for multihop relay networks

    KAUST Repository

    Khan, Fahd Ahmed

    2011-07-01

    Performance of multihop cooperative networks depends on the routing protocols employed. In this paper we propose the last-n-hop selection protocol, the dual path protocol, the forward-backward last-n-hop selection protocol and the forward-backward dual path protocol for the routing of data through multihop relay networks. The average symbol error probability performance of the schemes is analysed by simulations. It is shown that close to optimal performance can be achieved by using the last-n-hop selection protocol and its forward-backward variant. Furthermore we also compute the complexity of the protocols in terms of number of channel state information required and the number of comparisons required for routing the signal through the network. © 2011 IEEE.

  6. Decode and Zero-Forcing Forward Relaying with Relay Selection in Cognitive Radio Systems

    KAUST Repository

    Park, Kihong

    2014-05-01

    In this paper, we investigate a cognitive radio (CR) relay network with multiple relay nodes that help forwarding the signal of CR users. Best relay selection is considered to take advantage of its low complexity of implementation. When the primary user (PU) is located close to the relay nodes, the performance of the secondary network is severely degraded due to the interference power constraint during the transmission in the second hop. We propose a decode and zero-forcing forward scheme to suppress the interference power at the relay nodes and analyze the statistics of the end-to-end signal-to-noise ratio when the relay nodes are located arbitrarily and experience therefore non-identical Rayleigh fading channels. Numerical results validate our theoretical results and show that our proposed scheme improves the performance of the CR network when the PU is close to the relay nodes. © 2014 IEEE.

  7. Protective relay

    International Nuclear Information System (INIS)

    Lim, Mu Ji; Jung, Hae Sang

    1974-10-01

    This book is divided into two chapters, which deals with protective relay. The first chapter deals with the basic knowledge of relay on development of relay, classification of protective relay, rating of protective relay general structure of protective relay, detecting of ground protection, about point of contact, operating relay and trip relaying. The second chapter is about structure and explanation of relay on classification by structure such as motor type and moving-coil type, explanation of other relays over current relay, over voltage relay, short voltage relay, relay for power, relay for direction, test of over voltage relay, test of short voltage relay and test of directional circuit relay.

  8. Optimized Power Allocation and Relay Location Selection in Cooperative Relay Networks

    Directory of Open Access Journals (Sweden)

    Jianrong Bao

    2017-01-01

    Full Text Available An incremental selection hybrid decode-amplify forward (ISHDAF scheme for the two-hop single relay systems and a relay selection strategy based on the hybrid decode-amplify-and-forward (HDAF scheme for the multirelay systems are proposed along with an optimized power allocation for the Internet of Thing (IoT. Given total power as the constraint and outage probability as an objective function, the proposed scheme possesses good power efficiency better than the equal power allocation. By the ISHDAF scheme and HDAF relay selection strategy, an optimized power allocation for both the source and relay nodes is obtained, as well as an effective reduction of outage probability. In addition, the optimal relay location for maximizing the gain of the proposed algorithm is also investigated and designed. Simulation results show that, in both single relay and multirelay selection systems, some outage probability gains by the proposed scheme can be obtained. In the comparison of the optimized power allocation scheme with the equal power allocation one, nearly 0.1695 gains are obtained in the ISHDAF single relay network at a total power of 2 dB, and about 0.083 gains are obtained in the HDAF relay selection system with 2 relays at a total power of 2 dB.

  9. Partial relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz; Alouini, Mohamed-Slim; Hasna, Mazen Omar; Qaraqe, Khalid A.

    2012-01-01

    In a communication system with multiple cooperative relays, selecting the best relay utilizes the available spectrum more efficiently. However, selective relaying poses a different problem in underlay cognitive networks compared to the traditional cooperative networks due to interference thresholds to the primary users. In most cases, a best relay is the one which provides the maximum end-to-end signal to noise ratio (SNR). This approach needs plenty of instantaneous channel state information (CSI). The CSI burden could be reduced by partial relay selection. In this paper, a partial relay selection scheme is presented and analyzed for an underlay cognitive network with fixed gain relays operating in the vicinity of a primary user. The system model is adopted in a way that each node needs minimal CSI to perform its task. The best relay is chosen on the basis of maximum source to relay link SNR which then forwards the message to the destination. We derive closed form expressions for the received SNR distributions, system outage, probability of bit error and average channel capacity of the system. The derived results are confirmed through simulations. © 2012 IEEE.

  10. Partial relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-05-01

    In a communication system with multiple cooperative relays, selecting the best relay utilizes the available spectrum more efficiently. However, selective relaying poses a different problem in underlay cognitive networks compared to the traditional cooperative networks due to interference thresholds to the primary users. In most cases, a best relay is the one which provides the maximum end-to-end signal to noise ratio (SNR). This approach needs plenty of instantaneous channel state information (CSI). The CSI burden could be reduced by partial relay selection. In this paper, a partial relay selection scheme is presented and analyzed for an underlay cognitive network with fixed gain relays operating in the vicinity of a primary user. The system model is adopted in a way that each node needs minimal CSI to perform its task. The best relay is chosen on the basis of maximum source to relay link SNR which then forwards the message to the destination. We derive closed form expressions for the received SNR distributions, system outage, probability of bit error and average channel capacity of the system. The derived results are confirmed through simulations. © 2012 IEEE.

  11. A genetic algorithm for multiple relay selection in two-way relaying cognitive radio networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-09-01

    In this paper, we investigate a multiple relay selection scheme for two-way relaying cognitive radio networks where primary users and secondary users operate on the same frequency band. More specifically, cooperative relays using Amplifyand- Forward (AF) protocol are optimally selected to maximize the sum rate of the secondary users without degrading the Quality of Service (QoS) of the primary users by respecting a tolerated interference threshold. A strong optimization tool based on genetic algorithm is employed to solve our formulated optimization problem where discrete relay power levels are considered. Our simulation results show that the practical heuristic approach achieves almost the same performance of the optimal multiple relay selection scheme either with discrete or continuous power distributions. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.

  12. Optimal relay selection and power allocation for cognitive two-way relaying networks

    KAUST Repository

    Pandarakkottilil, Ubaidulla; Aï ssa, Sonia

    2012-01-01

    In this paper, we present an optimal scheme for power allocation and relay selection in a cognitive radio network where a pair of cognitive (or secondary) transceiver nodes communicate with each other assisted by a set of cognitive two-way relays

  13. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    Aitor del Coso

    2007-11-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of N wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, 𝒞=log⁡2(W0(N. Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  14. A performance analysis in AF full duplex relay selection network

    Science.gov (United States)

    Ngoc, Long Nguyen; Hong, Nhu Nguyen; Loan, Nguyen Thi Phuong; Kieu, Tam Nguyen; Voznak, Miroslav; Zdralek, Jaroslav

    2018-04-01

    This paper studies on the relaying selective matter in amplify-and-forward (AF) cooperation communication with full-duplex (FD) activity. Various relay choice models supposing the present of different instant information are investigated. We examine a maximal relaying choice that optimizes the instant FD channel capacity and asks for global channel state information (CSI) as well as partial CSI learning. To make comparison easy, accurate outage probability clauses and asymptote form of these strategies that give a diversity rank are extracted. From that, we can see clearly that the number of relays, noise factor, the transmittance coefficient as well as the information transfer power had impacted on their performance. Besides, the optimal relay selection (ORS) model can promote than that of the partial relay selection (PRS) model.

  15. A low complexity algorithm for multiple relay selection in two-way relaying Cognitive Radio networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-06-01

    In this paper, a multiple relay selection scheme for two-way relaying cognitive radio network is investigated. We consider a cooperative Cognitive Radio (CR) system with spectrum sharing scenario using Amplify-and-Forward (AF) protocol, where licensed users and unlicensed users operate on the same frequency band. The main objective is to maximize the sum rate of the unlicensed users allowed to share the spectrum with the licensed users by respecting a tolerated interference threshold. A practical low complexity heuristic approach is proposed to solve our formulated optimization problem. Selected numerical results show that the proposed algorithm reaches a performance close to the performance of the optimal multiple relay selection scheme either with discrete or continuous power distributions while providing a considerable saving in terms of computational complexity. In addition, these results show that our proposed scheme significantly outperforms the single relay selection scheme. © 2013 IEEE.

  16. Analysis of Relay Selection Game in a Cooperative Communication Scenario

    DEFF Research Database (Denmark)

    Craciunescu, Razvan; Mihovska, Albena; Halunga, Simona

    This paper analysis the performances of a proposed set of functions that model the relay selection process in a cooperative communication scenario. The behavior and influence proposed functions create a mechanism for selecting the best relays to be used to send certain types of data. The mechanism...... of comparison between the bit error rate of the proposed mechanism and the direct communication....

  17. Full-Duplex Relay Selection in Cognitive Underlay Networks

    KAUST Repository

    Khafagy, Mohammad Galal

    2017-09-30

    In this work, we analyze the performance of full-duplex relay selection (FDRS) in spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay(s), thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint, which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic FDRS with residual self-interference (RSI) by deriving the exact cumulative distribution function of its end-to-end signal-to-interference-plus-noise ratio under Nakagami-m fading. We also evaluate the offered diversity gain of relay selection for different full-duplex cooperation schemes in the presence/absence of a direct source-destination link. When the adopted RSI link gain model is sublinear in the relay power, which agrees with recent research findings, we show that remarkable diversity gain can be recovered even in the presence of an interfering direct link. Second, we evaluate the end-to-end performance of FDRS with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

  18. Optimal relay selection and power allocation for cognitive two-way relaying networks

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2012-06-01

    In this paper, we present an optimal scheme for power allocation and relay selection in a cognitive radio network where a pair of cognitive (or secondary) transceiver nodes communicate with each other assisted by a set of cognitive two-way relays. The secondary nodes share the spectrum with a licensed primary user (PU), and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. We propose joint relay selection and optimal power allocation among the secondary user (SU) nodes achieving maximum throughput under transmit power and PU interference constraints. A closed-form solution for optimal allocation of transmit power among the SU transceivers and the SU relay is presented. Furthermore, numerical simulations and comparisons are presented to illustrate the performance of the proposed scheme. © 2012 IEEE.

  19. Multiple relay selection for delay-limited applications

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-12-01

    A multiple relay selection system model that implements the decode-and-forward mode is investigated. All communication nodes are assumed to be equipped by multiple antennas. Furthermore, lattices space-time coded multiple-input multiple-output half duplex channel is applied. The main goal is to increase the throughput of the system by selecting multiple number of relays. The selection criteria depends on the maximum decoding delay at relays where the system implements a decoding time-out algorithm at each relay. This leads to a significant saving in the overall system power consumptions and attempts to solve the relays synchronization problem. All results are presented using numerical simulations. © 2012 IEEE.

  20. Multiple relay selection for delay-limited applications

    KAUST Repository

    Alsharoa, Ahmad M.; Abediseid, Walid; Alouini, Mohamed-Slim

    2013-01-01

    A multiple relay selection system model that implements the decode-and-forward mode is investigated. All communication nodes are assumed to be equipped by multiple antennas. Furthermore, lattices space-time coded multiple-input multiple-output half

  1. The sequence relay selection strategy based on stochastic dynamic programming

    Science.gov (United States)

    Zhu, Rui; Chen, Xihao; Huang, Yangchao

    2017-07-01

    Relay-assisted (RA) network with relay node selection is a kind of effective method to improve the channel capacity and convergence performance. However, most of the existing researches about the relay selection did not consider the statically channel state information and the selection cost. This shortage limited the performance and application of RA network in practical scenarios. In order to overcome this drawback, a sequence relay selection strategy (SRSS) was proposed. And the performance upper bound of SRSS was also analyzed in this paper. Furthermore, in order to make SRSS more practical, a novel threshold determination algorithm based on the stochastic dynamic program (SDP) was given to work with SRSS. Numerical results are also presented to exhibit the performance of SRSS with SDP.

  2. Selection combining for noncoherent decode-and-forward relay networks

    Directory of Open Access Journals (Sweden)

    Nguyen Ha

    2011-01-01

    Full Text Available Abstract This paper studies a new decode-and-forward relaying scheme for a cooperative wireless network composed of one source, K relays, and one destination and with binary frequency-shift keying modulation. A single threshold is employed to select retransmitting relays as follows: a relay retransmits to the destination if its decision variable is larger than the threshold; otherwise, it remains silent. The destination then performs selection combining for the detection of transmitted information. The average end-to-end bit-error-rate (BER is analytically determined in a closed-form expression. Based on the derived BER, the problem of choosing an optimal threshold or jointly optimal threshold and power allocation to minimize the end-to-end BER is also investigated. Both analytical and simulation results reveal that the obtained optimal threshold scheme or jointly optimal threshold and power-allocation scheme can significantly improve the BER performance compared to a previously proposed scheme.

  3. Generalized instantly decodable network coding for relay-assisted networks

    KAUST Repository

    Elmahdy, Adel M.; Sorour, Sameh; Seddik, Karim G.

    2013-01-01

    which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate

  4. Consistent sensor, relay, and link selection in wireless sensor networks

    NARCIS (Netherlands)

    Arroyo Valles, M.D.R.; Simonetto, A.; Leus, G.J.T.

    2017-01-01

    In wireless sensor networks, where energy is scarce, it is inefficient to have all nodes active because they consume a non-negligible amount of battery. In this paper we consider the problem of jointly selecting sensors, relays and links in a wireless sensor network where the active sensors need

  5. Asymptotic analysis for Nakagami-m fading channels with relay selection

    KAUST Repository

    Zhong, Caijun; Wong, Kaikit; Jin, Shi; Alouini, Mohamed-Slim; Ratnarajah, Tharm

    2011-01-01

    In this paper, we analyze the asymptotic outage probability performance of both decode-and-forward (DF) and amplify-and-forward (AF) relaying systems using partial relay selection and the "best" relay selection schemes for Nakagami-m fading channels

  6. Secure relay selection based on learning with negative externality in wireless networks

    Science.gov (United States)

    Zhao, Caidan; Xiao, Liang; Kang, Shan; Chen, Guiquan; Li, Yunzhou; Huang, Lianfen

    2013-12-01

    In this paper, we formulate relay selection into a Chinese restaurant game. A secure relay selection strategy is proposed for a wireless network, where multiple source nodes send messages to their destination nodes via several relay nodes, which have different processing and transmission capabilities as well as security properties. The relay selection utilizes a learning-based algorithm for the source nodes to reach their best responses in the Chinese restaurant game. In particular, the relay selection takes into account the negative externality of relay sharing among the source nodes, which learn the capabilities and security properties of relay nodes according to the current signals and the signal history. Simulation results show that this strategy improves the user utility and the overall security performance in wireless networks. In addition, the relay strategy is robust against the signal errors and deviations of some user from the desired actions.

  7. Use of Behavior and Influence Functions for Relay Selection in Cooperative Communications

    DEFF Research Database (Denmark)

    Craciunescu, Razvan; Mihovska, Albena Dimitrova; Prasad, Ramjee

    2015-01-01

    This paper uses a novel set of functions to model the relay selection process in a scenario of cooperative wireless communications. We define a utility function that reflects the behavior and influence that a selected relay may have on the quality of the link to be established for the forwarding...... of data. The utility function takes into account also the strategies of other players. To this end, we define a relay selection game and a supporting Nash Equilibrium (NE) algorithm for the choice of a relay during communication. The successful selection of a relay is evaluated by simulations in terms...

  8. Asymptotic analysis for Nakagami-m fading channels with relay selection

    KAUST Repository

    Zhong, Caijun

    2011-06-01

    In this paper, we analyze the asymptotic outage probability performance of both decode-and-forward (DF) and amplify-and-forward (AF) relaying systems using partial relay selection and the "best" relay selection schemes for Nakagami-m fading channels. We derive their respective outage probability expressions in the asymptotic high signal-to-noise ratio (SNR) regime, from which the diversity order and coding gain are analyzed. In addition, we investigate the impact of power allocation between the source and relay terminals and derive the diversity-multiplexing tradeoff (DMT) for these relay selection systems. The theoretical findings suggest that partial relay selection can improve the diversity of the system and can achieve the same DMT as the "best" relay selection scheme under certain conditions. © 2011 IEEE.

  9. Optimized Policies for Improving Fairness of Location-based Relay Selection

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

    2013-01-01

    For WLAN systems in which relaying is used to improve throughput performance for nodes located at the cell edge, node mobility and information collection delays can have a significant impact on the performance of a relay selection scheme. In this paper we extend our existing Markov Chain modeling...... framework for relay selection to allow for efficient calculation of relay policies given either mean throughput or kth throughput percentile as optimization criterium. In a scenario with static access point, static relay, and a mobile destination node, the kth throughput percentile optimization...

  10. Outage Probability versus Fairness Trade-off in Opportunistic Relay Selection with Outdated CSI

    Directory of Open Access Journals (Sweden)

    Vicario JoseLopez

    2009-01-01

    Full Text Available We analyze the existing trade-offs in terms of system performance versus fairness of a cooperative system based on opportunistic relay selection (ORS and with outdated channel state information (CSI. In particular, system performance is analytically evaluated in terms of outage probability, and the fairness behavior is assessed based on the power consumption at the different relays. In order to improve the fairness behavior of ORS while keeping the selection diversity gain, we propose a relay selection mechanism where the relay with the highest normalized signal-to-noise ratio (SNR is selected for relaying the source's information. The proposed strategy is compared with existing relay selection strategies by adopting a novel graphical representation inspired by expected profit versus risk plots used in modern portfolio theory. As shown in the paper, this strategy allows operating the system in more favorable points of the outage versus fairness region.

  11. Energy-Efficient Relay Selection Scheme for Physical Layer Security in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Li Jiang

    2015-01-01

    selection and dynamic power allocation in order to maximize SC and to minimize energy consumption. Moreover, we consider finite-state Markov channels and residual relay energy in the relay selection and power allocation process. Specifically, the formulation of the proposed relay selection and power allocation scheme is based on the restless bandit problem, which is solved by the primal-dual index heuristic algorithm. Additionally, the obtained optimal relay selection policy has an indexability property that dramatically reduces the computational complexity. Numerical results are presented to show that our proposed scheme has the maximum SC and minimum energy consumption compared to the existing ones.

  12. Location-based Relay Selection and Power Adaptation Enabling Simultaneous Transmissions

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2010-01-01

    Relaying is a well known technique to extend coverage and improve conditions for nodes in the outer coverage region. In this paper we propose a relaying scheme that exploits the spatial separation of relay and destination pairs to improve throughput by allowing simultaneous transmissions....... The proposed scheme is a cross-layer optimization for two-hop relaying that uses position information to jointly optimize relay selection and relay transmit power, maximizing Medium Access Control layer throughput. Further, in order to calculate the expected throughput, we apply a probabilistic model...... that takes into account MAC retransmissions and timing behavior of the IEEE 802.11 Distributed Coordination Function mode. Our results show an increase in throughput of approximately 20% is achievable for the proposed scheme when compared to two-hop relaying in the analyzed scenario....

  13. Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

    KAUST Repository

    Xia, Minghua

    2012-11-01

    For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.

  14. Adaptive transmission based on multi-relay selection and rate-compatible LDPC codes

    Science.gov (United States)

    Su, Hualing; He, Yucheng; Zhou, Lin

    2017-08-01

    In order to adapt to the dynamical changeable channel condition and improve the transmissive reliability of the system, a cooperation system of rate-compatible low density parity check (RC-LDPC) codes combining with multi-relay selection protocol is proposed. In traditional relay selection protocol, only the channel state information (CSI) of source-relay and the CSI of relay-destination has been considered. The multi-relay selection protocol proposed by this paper takes the CSI between relays into extra account in order to obtain more chances of collabration. Additionally, the idea of hybrid automatic request retransmission (HARQ) and rate-compatible are introduced. Simulation results show that the transmissive reliability of the system can be significantly improved by the proposed protocol.

  15. Toward distributed relay selection for opportunistic amplify-and-forward transmission

    KAUST Repository

    Tourki, Kamel

    2011-05-01

    Opportunistic relaying in cooperative communication depends on careful relay selection. However the traditional centralized method used for opportunistic Amplify-and-Forward (OAF) protocols requires precise measurements of channel state information (CSI) at the destination (CSI-OAF). In this paper, we propose a distributed relay selection framework for opportunistic AF (D-OAF) cooperative communications and offer an accurate performance analysis based on exact statistics of the local signalto- noise ratios of the best relay. Furthermore, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures, and we compare our new results with their CSI-based counterparts. © 2011 IEEE.

  16. Performance analysis of selective cooperation with fixed gain relays in Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz; Hasna, Mazen Omar; Alouini, Mohamed-Slim

    2012-01-01

    Selecting the best relay using the maximum signal to noise ratio (SNR) among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. In this paper, we analyze the performance of the best relay selection scheme with fixed gain relays operating in Nakagami-. m channels. We first derive the probability density function (PDF) of upper bounded end-to-end SNR of the relay link. Using this PDF, we derive some key performance parameters for the system including average bit error probability and average channel capacity. The analytical results are verified through Monte Carlo simulations. © 2012 Elsevier B.V.

  17. Performance analysis of selective cooperation with fixed gain relays in Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

    Selecting the best relay using the maximum signal to noise ratio (SNR) among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. In this paper, we analyze the performance of the best relay selection scheme with fixed gain relays operating in Nakagami-. m channels. We first derive the probability density function (PDF) of upper bounded end-to-end SNR of the relay link. Using this PDF, we derive some key performance parameters for the system including average bit error probability and average channel capacity. The analytical results are verified through Monte Carlo simulations. © 2012 Elsevier B.V.

  18. Full-Duplex opportunistic relay selection in future spectrum-sharing networks

    KAUST Repository

    Khafagy, Mohammad Galal; Alouini, Mohamed-Slim; Aï ssa, Sonia

    2015-01-01

    We propose and analyze the performance of full-duplex relay selection in primary/secondary spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay, thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic relay selection among a cluster of full-duplex decode-and-forward relays with self-interference by deriving the exact cumulative distribution function of its end-to-end signal-to-noise ratio. Second, we evaluate the end-to-end performance of relay selection with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

  19. Full-Duplex opportunistic relay selection in future spectrum-sharing networks

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-06-01

    We propose and analyze the performance of full-duplex relay selection in primary/secondary spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay, thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic relay selection among a cluster of full-duplex decode-and-forward relays with self-interference by deriving the exact cumulative distribution function of its end-to-end signal-to-noise ratio. Second, we evaluate the end-to-end performance of relay selection with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

  20. Relay selection in underlay cognitive networks with fixed transmission power nodes

    KAUST Repository

    Hussain, Syed Imtiaz

    2013-07-31

    Underlay cognitive networks operate simultaneously with primary networks satisfying stringent interference constraints, which reduces their transmission power and coverage area. To reach remote destinations, secondary sources use relaying techniques. Selecting the best relay among the available ones is a well known technique. Recently, selective cooperation is investigated in cognitive networks where the secondary nodes can adapt their transmission power to always satisfy the interference threshold. In this paper, we investigate a situation where the secondary nodes have a fixed transmission power and may violate the interference threshold. We present two relay selection schemes; the first one excludes the relays not satisfying the interference constraint and then picks up a relay from the remaining ones that can provide the maximum signal-to-noise ratio (SNR). The other scheme uses a quotient of the relay link SNR and the interference from the relay to the primary user and optimizes it to maximise the relay link SNR. We derive closed form expressions for outage probability, bit error rate, channel capacity and diversity of the system for both schemes by using tight approximations. We also study mutual effects of interference. Simulation results confirm the analytical results and reveal that the relay selection is feasible at low SNRs. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Relay discovery and selection for large-scale P2P streaming.

    Directory of Open Access Journals (Sweden)

    Chengwei Zhang

    Full Text Available In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS, can only achieve a coarse estimation of peers' network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used "best-out-of-K" selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT. When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.

  2. On the benefits of location-based relay selection in mobile wireless networks

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2016-01-01

    We consider infrastructure-based mobile networks that are assisted by a single relay transmission where both the downstream destination and relay nodes are mobile. Selecting the optimal transmission path for a destination node requires up-to-date link quality estimates of all relevant links....... If the relay selection is based on link quality measurements, the number of links to update grows quadratically with the number of nodes, and measurements need to be updated frequently when nodes are mobile. In this paper, we consider a location-based relay selection scheme where link qualities are estimated...... from node positions; in the scenario of a node-based location system such as GPS, the location-based approach reduces signaling overhead, which in this case only grows linearly with the number of nodes. This paper studies these two relay selection approaches and investigates how they are affected...

  3. On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-02-25

    We evaluate the outage performance in a three-terminal full-duplex relay channel that adopts a selective decode-and-forward protocol, taking relay self-interference into account. Previous work focused on coverage extension scenarios where direct source-destination transmissions are neglected or considered as interference. In this work, we account for the relay self-interference, and exploit the cooperative diversity offered by the independently fading source/relay message replicas that arrive at the destination. We present an approximate, yet accurate, closed-form expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

  4. Impact of Primary User Traffic on Adaptive Transmission for Cognitive Radio with Partial Relay Selection

    KAUST Repository

    Rao, Anlei; Ma, Hao; Alouini, Mohamed-Slim; Chen, Yunfei

    2012-01-01

    transmission, when the secondary user adopts adaptive transmission with a relay partially selected. From the numerical results, we can see that the primary user traffic seriously degrades average BER. The worse-link partial selection can perform almost as well

  5. Best relay selection using SNR and interference quotient for underlay cognitive networks

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-06-01

    Cognitive networks in underlay settings operate simultaneously with the primary networks satisfying stringent interference limits. This condition forces them to operate with low transmission powers and confines their area of coverage. In an effort to reach remote destinations, underlay cognitive sources make use of relaying techniques. Selecting the best relay among those who are ready to cooperate is different in underlay settings than traditional non-cognitive networks. In this paper, we present a relay selection scheme which uses the quotient of the relay link signal to noise ratio (SNR) and the interference generated from the relay to the primary user to choose the best relay. The proposed scheme optimizes this quotient in a way to maximize the relay link SNR above a certain value whereas the interference is kept below a defined threshold. We derive closed expressions for the outage probability and bit error probability of the system incorporating this scheme. Simulation results confirm the validity of the analytical results and reveal that the relay selection in cognitive environment is feasible in low SNR regions. © 2012 IEEE.

  6. Relay selection in cooperative communication systems over continuous time-varying fading channel

    Directory of Open Access Journals (Sweden)

    Ke Geng

    2017-02-01

    Full Text Available In this paper, we study relay selection under outdated channel state information (CSI in a decode-and-forward (DF cooperative system. Unlike previous researches on cooperative communication under outdated CSI, we consider that the channel varies continuously over time, i.e., the channel not only changes between relay selection and data transmission but also changes during data transmission. Thus the level of accuracy of the CSI used in relay selection degrades with data transmission. We first evaluate the packet error rate (PER of the cooperative system under continuous time-varying fading channel, and find that the PER performance deteriorates more seriously under continuous time-varying fading channel than when the channel is assumed to be constant during data transmission. Then, we propose a repeated relay selection (RRS strategy to improve the PER performance, in which the forwarded data is divided into multiple segments and relay is reselected before the transmission of each segment based on the updated CSI. Finally, we propose a combined relay selection (CRS strategy which takes advantage of three different relay selection strategies to further mitigate the impact of outdated CSI.

  7. Impact of Primary User Traffic on Adaptive Transmission for Cognitive Radio with Partial Relay Selection

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive relay system, the secondary user is permitted to transmit data via a relay when licensed frequency bands are detected to be free. Previous studies mainly focus on reducing or limiting the interference of the secondary transmission on the primary users. On the other hand, however, the primary user traffic will also affect the data transmission performance of the secondary users. In this paper, we investigate the impact of the primary user traffic on the bit error rate (BER) of the secondary transmission, when the secondary user adopts adaptive transmission with a relay partially selected. From the numerical results, we can see that the primary user traffic seriously degrades average BER. The worse-link partial selection can perform almost as well as the global selection when the channel conditions of the source-relay links and the relay-destination links differ a lot. In addition, although the relay selection improves the spectral efficiency of the secondary transmission, numerical results show that it only has slight impact on the overall average BER, so that the robustness of the system will not be affected by the relay selection.

  8. Energy-efficient relay selection and optimal power allocation for performance-constrained dual-hop variable-gain AF relaying

    KAUST Repository

    Zafar, Ammar

    2013-12-01

    This paper investigates the energy-efficiency enhancement of a variable-gain dual-hop amplify-and-forward (AF) relay network utilizing selective relaying. The objective is to minimize the total consumed power while keeping the end-to-end signal-to-noise-ratio (SNR) above a certain peak value and satisfying the peak power constraints at the source and relay nodes. To achieve this objective, an optimal relay selection and power allocation strategy is derived by solving the power minimization problem. Numerical results show that the derived optimal strategy enhances the energy-efficiency as compared to a benchmark scheme in which both the source and the selected relay transmit at peak power. © 2013 IEEE.

  9. Energy-efficient relay selection and optimal power allocation for performance-constrained dual-hop variable-gain AF relaying

    KAUST Repository

    Zafar, Ammar; Radaydeh, Redha Mahmoud Mesleh; Chen, Yunfei; Alouini, Mohamed-Slim

    2013-01-01

    This paper investigates the energy-efficiency enhancement of a variable-gain dual-hop amplify-and-forward (AF) relay network utilizing selective relaying. The objective is to minimize the total consumed power while keeping the end-to-end signal

  10. Location-quality-aware policy optimisation for relay selection in mobile networks

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

    2016-01-01

    for resulting performance of such network optimizations. In mobile scenarios, the required information collection and forwarding causes delays that will additionally affect the reliability of the collected information and hence will influence the performance of the relay selection method. This paper analyzes...... the joint influence of these two factors in the decision process for the example of a mobile location-based relay selection approach using a continuous time Markov chain model. Efficient algorithms are developed based on this model to obtain optimal relay policies under consideration of localization errors....... Numerical results show how information update rates, forwarding delays, and location estimation errors affect these optimal policies and allow to conclude on the required accuracy of location-based systems for such mobile relay selection scenarios. A measurement-based indoor scenario with more complex...

  11. Minimax robust relay selection based on uncertain long-term CSI

    KAUST Repository

    Nisar, Muhammad Danish

    2014-02-01

    Cooperative communications via multiple relay nodes is known to provide the benefits of increase diversity and coverage. Simultaneous transmission via multiple relays, however, requires strong coordination between nodes either in terms of slot-based transmission or distributed space-time (ST) code implementation. Dynamically selecting a single best relay out of multiple relays and then using it alone for cooperative transmission alleviates the need for this strong coordination while still reaping the benefits of increased diversity and coverage. In this paper, we consider the design of relay selection (RS) under an imperfect knowledge of long-term channel state information (CSI) at the relay nodes, and we pursue minimax optimization to arrive at a robust RS approach that promises the best guarantee on the worst-case end-to-end signal-to-noise ratio (SNR). We provide some intuitive examples and extensive simulation results, not only in terms of worst-case SNR performance but also in terms of average bit-error-rate (BER) performance, to demonstrate the benefits of the proposed minimax robust RS scheme. © 2013 IEEE.

  12. Energy Efficiency Analysis of a Two Dimensional Cooperative Wireless Sensor Network with Relay Selection

    Directory of Open Access Journals (Sweden)

    M. Kakitani

    2013-06-01

    Full Text Available The energy efficiency of non-cooperative and cooperative transmissions are investigated in a two-dimensional wireless sensor network, considering a target outage probability and the same end-to-end throughput for all transmission schemes. The impact of the relay selection method in the cooperative schemes is also analyzed. We show that under non line-of-sight conditions the relay selection method has a greater impact in the energy efficiency than the availability of a return channel. By its turn, under line-of-sight conditions a return channel is more valuable to the energy efficiency of cooperative transmission than the specific relay selection method. Finally, we demonstrate that the energy efficiency advantage of the cooperative over the non-cooperative transmission increases with the distance among nodes and with the nodes density.

  13. Relay model for recruiting alcohol dependent patients in general hospitals--a single-blind pragmatic randomized trial

    DEFF Research Database (Denmark)

    Schwarz, Anne-Sophie; Bilberg, Randi; Bjerregaard, Lene Berit Skov

    2016-01-01

    - The Relay Model. METHOD/DESIGN: The study is a single-blind pragmatic randomized controlled trial including patients admitted to the hospital. The study group (n = 500) will receive an intervention, and the control group (n = 500) will be referred to treatment by usual procedures. All patients complete......://register.clinicaltrials.gov/by identifier: RESCueH_Relay NCT02188043 Project Relay Model for Recruiting Alcohol Dependent Patients in General Hospitals (TRN Registration: 07/09/2014)....

  14. Joint Transmit Antenna Selection and Power Allocation for ISDF Relaying Mobile-to-Mobile Sensor Networks.

    Science.gov (United States)

    Xu, Lingwei; Zhang, Hao; Gulliver, T Aaron

    2016-02-19

    The outage probability (OP) performance of multiple-relay incremental-selective decode-and-forward (ISDF) relaying mobile-to-mobile (M2M) sensor networks with transmit antenna selection (TAS) over N-Nakagami fading channels is investigated. Exact closed-form OP expressions for both optimal and suboptimal TAS schemes are derived. The power allocation problem is formulated to determine the optimal division of transmit power between the broadcast and relay phases. The OP performance under different conditions is evaluated via numerical simulation to verify the analysis. These results show that the optimal TAS scheme has better OP performance than the suboptimal scheme. Further, the power allocation parameter has a significant influence on the OP performance.

  15. Performance Analysis of Secrecy Outage Probability for AF-Based Partial Relay Selection with Outdated Channel Estimates

    Directory of Open Access Journals (Sweden)

    Kyu-Sung Hwang

    2017-01-01

    Full Text Available We study the secrecy outage probability of the amplify-and-forward (AF relaying protocol, which consists of one source, one destination, multiple relays, and multiple eavesdroppers. In this system, the aim is to transmit the confidential messages from a source to a destination via the selected relay in presence of eavesdroppers. Moreover, partial relay selection scheme is utilized for relay selection based on outdated channel state information where only neighboring channel information (source-relays is available and passive eavesdroppers are considered where a transmitter does not have any knowledge of eavesdroppers’ channels. Specifically, we offer the exact secrecy outage probability of the proposed system in a one-integral form as well as providing the asymptotic secrecy outage probability in a closed-form. Numerical examples are given to verify our provided analytical results for different system conditions.

  16. Social-Aware Relay Selection for Cooperative Multicast Device-to-Device Communications

    Directory of Open Access Journals (Sweden)

    Francesco Chiti

    2017-12-01

    Full Text Available The increasing use of social networks such as Facebook, Twitter, and Instagram to share photos, video streaming, and music among friends has generated a huge increase in the amount of data traffic over wireless networks. This social behavior has triggered new communication paradigms such as device-to-device (D2D and relaying communication schemes, which are both considered as strong drivers for the next fifth-generation (5G cellular systems. Recently, the social-aware layer and its relationship to and influence on the physical communications layer have gained great attention as emerging focus points. We focus here on the case of relaying communications to pursue the multicast data dissemination to a group of users forming a social community through a relay node, according to the extension of the D2D mode to the case of device-to-many devices. Moreover, in our case, the source selects the device to act as the relay among different users of the multicast group by taking into account both the propagation link conditions and the relay social-trust level with the constraint of minimizing the end-to-end content delivery delay. An optimization procedure is also proposed in order to achieve the best performance. Finally, numerical results are provided to highlight the advantages of considering the impact of social level on the end-to-end delivery delay in the integrated social–physical network in comparison with the classical relay-assisted multicast communications for which the relay social-trust level is not considered.

  17. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

    Choi, Seyeong; Hasna, Mazen Omar; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

  18. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

    Choi, Seyeong

    2011-06-01

    In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

  19. Relay selection and resource allocation for two-way DF-AF cognitive radio networks

    KAUST Repository

    Alsharoa, Ahmad M.; Bader, Faouzi; Alouini, Mohamed-Slim

    2013-01-01

    In this letter, the problem of relay selection and optimal resource allocation for two-way relaying cognitive radio networks using half duplex amplify-and-forward and decode-and-forward protocols is investigated. The primary and secondary users are assumed to access the spectrum simultaneously, in a way that the interference introduced to the primary users should be below a certain tolerated limit. Dual decomposition and subgradient methods are used to find the optimal power allocation. A suboptimal approach based on a genetic algorithm is also presented. Simulation results show that the proposed suboptimal algorithm offers a performance close to the optimal performance with a considerable complexity saving. © 2013 IEEE.

  20. Relay selection and resource allocation for two-way DF-AF cognitive radio networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-08-01

    In this letter, the problem of relay selection and optimal resource allocation for two-way relaying cognitive radio networks using half duplex amplify-and-forward and decode-and-forward protocols is investigated. The primary and secondary users are assumed to access the spectrum simultaneously, in a way that the interference introduced to the primary users should be below a certain tolerated limit. Dual decomposition and subgradient methods are used to find the optimal power allocation. A suboptimal approach based on a genetic algorithm is also presented. Simulation results show that the proposed suboptimal algorithm offers a performance close to the optimal performance with a considerable complexity saving. © 2013 IEEE.

  1. Location-based Mobile Relay Selection and Impact of Inaccurate Path Loss Model Parameters

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2010-01-01

    In this paper we propose a relay selection scheme which uses collected location information together with a path loss model for relay selection, and analyze the performance impact of mobility and different error causes on this scheme. Performance is evaluated in terms of bit error rate...... by simulations. The SNR measurement based relay selection scheme proposed previously is unsuitable for use with fast moving users in e.g. vehicular scenarios due to a large signaling overhead. The proposed location based scheme is shown to work well with fast moving users due to a lower signaling overhead...... in these situations. As the location-based scheme relies on a path loss model to estimate link qualities and select relays, the sensitivity with respect to inaccurate estimates of the unknown path loss model parameters is investigated. The parameter ranges that result in useful performance were found...

  2. Symbol Error Probability of DF Relay Selection over Arbitrary Nakagami-m Fading Channels

    Directory of Open Access Journals (Sweden)

    George C. Alexandropoulos

    2013-01-01

    Full Text Available We present a new analytical expression for the moment generating function (MGF of the end-to-end signal-to-noise ratio of dual-hop decode-and-forward (DF relaying systems with relay selection when operating over Nakagami-m fading channels. The derived MGF expression, which is valid for arbitrary values of the fading parameters of both hops, is subsequently utilized to evaluate the average symbol error probability (ASEP of M-ary phase shift keying modulation for the considered DF relaying scheme under various asymmetric fading conditions. It is shown that the MGF-based ASEP performance evaluation results are in excellent agreement with equivalent ones obtained by means of computer simulations, thus validating the correctness of the presented MGF expression.

  3. Performance analysis of best relay selection scheme for amplify-and-forward cooperative networks in identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2010-06-01

    In cooperative communication networks, the use of multiple relays between the source and the destination was proposed to increase the diversity gain. Since the source and all the relays must transmit on orthogonal channels, multiple relay cooperation is considered inefficient in terms of channel resources and bandwidth utilization. To overcome this problem, the concept of best relay selection was recently proposed. In this paper, we analyze the performance of the best relay selection scheme for a cooperative network with multiple relays operating in amplify-and-forward (AF) mode over identical Nakagami-m channels using exact source-relay-destination signal to noise ratio (SNR) expression. We derive accurate closed form expressions for various system parameters including probability density function (pdf) of end-to-end SNR, average output SNR, average probability of bit error and average channel capacity. T he analytical results are verified through extensive simulations. It is shown that the best relay selection scheme performs better than the regular all relay cooperation.

  4. The New Multipoint Relays Selection in OLSR using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Razali Ngah

    2012-06-01

    Full Text Available The standard Optimized Link State Routing (OLSR introduces an interesting concept, the multipoint relays (MPRs, to mitigate message overhead during the flooding process. We propose a new algorithm for MPRs selection to enhance the performance of OLSR using Particle Swarm Optimization Sigmoid Increasing Inertia Weight (PSOSIIW. The sigmoid increasing inertia weight has significance improve the particle swarm optimization (PSO in terms of simplicity and quick convergence towards optimum solution. The new fitness function of PSO-SIIW, packet delay of each node and degree of willingness are introduced to support MPRs selection in OLSR. We examine the throughput, packet loss and end-to-end delay of the proposed method using network simulator 2 (ns2.  Overall results indicate that OLSR-PSOSIIW has shown good performance compared to the standard OLSR and OLSR-PSO, particularly for the throughput and end-to-end delay. Generally the proposed OLSR-PSOSIIW shows advantage of using PSO for optimizing routing paths in the MPRs selection algorithm.

  5. Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

    KAUST Repository

    Xia, Minghua; Aissa, Sonia

    2012-01-01

    For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary

  6. On Secrecy Outage of Relay Selection in Underlay Cognitive Radio Networks over Nakagami-m Fading Channels

    KAUST Repository

    Lei, Hongjiang; Zhang, Huan; Ansari, Imran Shafique; Ren, Zhi; Pan, Gaofeng; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, the secrecy outage performance of an underlay cognitive decode-and-forward relay network over independent but not necessarily identical distributed (i.n.i.d) Nakagami-m fading channels is investigated, in which the secondary user transmitter communicates with the secondary destination via relays, and an eavesdropper attempts to overhear the information. Based on whether the channel state information (CSI) of the wiretap links is available or not, we analyze the secrecy outage performance with optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes, and multiple relays combining scheme (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for the secrecy outage probability with three different relay selection schemes are derived and verified by Monte-Carlo simulations. The numerical results illustrate that ORS scheme always outperforms SRS and MRC schemes, and SRS scheme is better than MRC scheme in the lower fading parameters scenario. Furthermore, through asymptotic analysis, we find that these three different schemes achieve the same secrecy diversity order, which is determined by the number of the relays, and the fading parameters of the links among the relays and the destination.

  7. On Secrecy Outage of Relay Selection in Underlay Cognitive Radio Networks over Nakagami-m Fading Channels

    KAUST Repository

    Lei, Hongjiang

    2017-10-02

    In this paper, the secrecy outage performance of an underlay cognitive decode-and-forward relay network over independent but not necessarily identical distributed (i.n.i.d) Nakagami-m fading channels is investigated, in which the secondary user transmitter communicates with the secondary destination via relays, and an eavesdropper attempts to overhear the information. Based on whether the channel state information (CSI) of the wiretap links is available or not, we analyze the secrecy outage performance with optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes, and multiple relays combining scheme (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for the secrecy outage probability with three different relay selection schemes are derived and verified by Monte-Carlo simulations. The numerical results illustrate that ORS scheme always outperforms SRS and MRC schemes, and SRS scheme is better than MRC scheme in the lower fading parameters scenario. Furthermore, through asymptotic analysis, we find that these three different schemes achieve the same secrecy diversity order, which is determined by the number of the relays, and the fading parameters of the links among the relays and the destination.

  8. Relay Selections for Security and Reliability in Mobile Communication Networks over Nakagami-m Fading Channels

    Directory of Open Access Journals (Sweden)

    Hongji Huang

    2017-01-01

    Full Text Available This paper studies the relay selection schemes in mobile communication system over Nakagami-m channel. To make efficient use of licensed spectrum, both single relay selection (SRS scheme and multirelays selection (MRS scheme over the Nakagami-m channel are proposed. Also, the intercept probability (IP and outage probability (OP of the proposed SRS and MRS for the communication links depending on realistic spectrum sensing are derived. Furthermore, this paper assesses the manifestation of conventional direct transmission scheme to compare with the proposed SRS and MRS ones based on the Nakagami-m channel, and the security-reliability trade-off (SRT performance of the proposed schemes and the conventional schemes is well investigated. Additionally, the SRT of the proposed SRS and MRS schemes is demonstrated better than that of direct transmission scheme over the Nakagami-m channel, which can protect the communication transmissions against eavesdropping attacks. Additionally, simulation results show that our proposed relay selection schemes achieve better SRT performance than that of conventional direct transmission over the Nakagami-m channel.

  9. Overlay Cognitive Radios With Channel-Aware Adaptive Link Selection and Buffer-Aided Relaying

    KAUST Repository

    Shaqfeh, Mohammad

    2015-08-01

    The aim of this work is to maximize the long-term average achievable rate region of a primary and a secondary source-destination pairs operating in an overlay setup over block-fading channels. To achieve this objective, we propose an opportunistic strategy to grant channel access to the primary and secondary sources based on the channel conditions in order to exploit the available multiple-link diversity gains in the system. The secondary source has causal knowledge of the primary messages and it acts as a relay of the primary source in return for getting access to the channel. To maximize the gains of relaying, the relay and destination are equipped with buffers to enable the use of channel-aware adaptive link selection. We propose and optimize different link selection policies and characterize their expected achievable rates. Also, we provide several numerical results to demonstrate the evident mutual benefits of buffer-aided cooperation and adaptive link selection to the primary and the secondary source-destination pairs. © 1972-2012 IEEE.

  10. Overlay Cognitive Radios With Channel-Aware Adaptive Link Selection and Buffer-Aided Relaying

    KAUST Repository

    Shaqfeh, Mohammad; Zafar, Ammar; Alnuweiri, Hussein; Alouini, Mohamed-Slim

    2015-01-01

    The aim of this work is to maximize the long-term average achievable rate region of a primary and a secondary source-destination pairs operating in an overlay setup over block-fading channels. To achieve this objective, we propose an opportunistic strategy to grant channel access to the primary and secondary sources based on the channel conditions in order to exploit the available multiple-link diversity gains in the system. The secondary source has causal knowledge of the primary messages and it acts as a relay of the primary source in return for getting access to the channel. To maximize the gains of relaying, the relay and destination are equipped with buffers to enable the use of channel-aware adaptive link selection. We propose and optimize different link selection policies and characterize their expected achievable rates. Also, we provide several numerical results to demonstrate the evident mutual benefits of buffer-aided cooperation and adaptive link selection to the primary and the secondary source-destination pairs. © 1972-2012 IEEE.

  11. End-to-End Joint Antenna Selection Strategy and Distributed Compress and Forward Strategy for Relay Channels

    Directory of Open Access Journals (Sweden)

    Rahul Vaze

    2009-01-01

    Full Text Available Multihop relay channels use multiple relay stages, each with multiple relay nodes, to facilitate communication between a source and destination. Previously, distributed space-time codes were proposed to maximize the achievable diversity-multiplexing tradeoff; however, they fail to achieve all the points of the optimal diversity-multiplexing tradeoff. In the presence of a low-rate feedback link from the destination to each relay stage and the source, this paper proposes an end-to-end antenna selection (EEAS strategy as an alternative to distributed space-time codes. The EEAS strategy uses a subset of antennas of each relay stage for transmission of the source signal to the destination with amplifying and forwarding at each relay stage. The subsets are chosen such that they maximize the end-to-end mutual information at the destination. The EEAS strategy achieves the corner points of the optimal diversity-multiplexing tradeoff (corresponding to maximum diversity gain and maximum multiplexing gain and achieves better diversity gain at intermediate values of multiplexing gain, versus the best-known distributed space-time coding strategies. A distributed compress and forward (CF strategy is also proposed to achieve all points of the optimal diversity-multiplexing tradeoff for a two-hop relay channel with multiple relay nodes.

  12. BICM-based cooperative communication systems with relay selection: Constellation and multiplexer design

    KAUST Repository

    Malik, Muhammad Talha

    2014-09-01

    We propose a new bit-interleaved coded modulation (BICM)-based cooperative communication system where different BICM modules can be optimized jointly considering the average signal to noise ratios of the direct and the two-hop Rayleigh fading channels. As such, the full benefit of BICM can be exploited in the context of cooperative communication. Our design considers cooperative communication systems with so called max-min relay selection scheme that has no loss in performance in terms of diversity- multiplexing trade off in orthogonal cooperation. The presented numerical results for rate 1/2 convolutional code with 8-ary pulse amplitude modulation equivalently 64-ary quadrature amplitude modulation show that the proposed design can offer gains up to 1.4 dB over the traditional BICM design for a target bit error rate of 10-6. Moreover the results show that the amount of gain depends on the relays\\' positions and increases with the number of relays available for selection.

  13. On the performance of future full-duplex relay selection networks

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-09-01

    In this work, we evaluate the performance of relay selection over Nakagami-m fading channels in the presence of a cluster of full-duplex decode-and-forward relays with self-interference. Specifically, we derive the exact cumulative distribution function of the end-to-end signal-to-interference-plus-noise ratio in the presence of a direct source-destination link. When a direct link exists, all dual-hop paths become mutually correlated due to the common direct-link interference. The presented exact results enable the evaluation of the outage performance and system throughput for fixed-rate transmission systems. The theoretical findings are verified by numerical simulations, where the severity of fading effect in the residual self-interference link is also discussed.

  14. On the performance of future full-duplex relay selection networks

    KAUST Repository

    Khafagy, Mohammad Galal; Alouini, Mohamed-Slim; Aissa, Sonia

    2015-01-01

    In this work, we evaluate the performance of relay selection over Nakagami-m fading channels in the presence of a cluster of full-duplex decode-and-forward relays with self-interference. Specifically, we derive the exact cumulative distribution function of the end-to-end signal-to-interference-plus-noise ratio in the presence of a direct source-destination link. When a direct link exists, all dual-hop paths become mutually correlated due to the common direct-link interference. The presented exact results enable the evaluation of the outage performance and system throughput for fixed-rate transmission systems. The theoretical findings are verified by numerical simulations, where the severity of fading effect in the residual self-interference link is also discussed.

  15. Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels.

    Science.gov (United States)

    Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

    2016-02-26

    In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source's radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks.

  16. Performance Analysis of Selective Decode-and-Forward Multinode Incremental Relaying with Maximal Ratio Combining

    KAUST Repository

    Hadjtaieb, Amir

    2013-09-12

    In this paper, we propose an incremental multinode relaying protocol with arbitrary N-relay nodes that allows an efficient use of the channel spectrum. The destination combines the received signals from the source and the relays using maximal ratio Combining (MRC). The transmission ends successfully once the accumulated signal-to-noise ratio (SNR) exceeds a predefined threshold. The number of relays participating in the transmission is adapted to the channel conditions based on the feedback from the destination. The use of incremental relaying allows obtaining a higher spectral efficiency. Moreover, the symbol error probability (SEP) performance is enhanced by using MRC at the relays. The use of MRC at the relays implies that each relay overhears the signals from the source and all previous relays and combines them using MRC. The proposed protocol differs from most of existing relaying protocol by the fact that it combines both incremental relaying and MRC at the relays for a multinode topology. Our analyses for a decode-and-forward mode show that: (i) compared to existing multinode relaying schemes, the proposed scheme can essentially achieve the same SEP performance but with less average number of time slots, (ii) compared to schemes without MRC at the relays, the proposed scheme can approximately achieve a 3 dB gain.

  17. Multi-diversity combining and selection for relay-assisted mixed RF/FSO system

    Science.gov (United States)

    Chen, Li; Wang, Weidong

    2017-12-01

    We propose and analyze multi-diversity combining and selection to enhance the performance of relay-assisted mixed radio frequency/free-space optics (RF/FSO) system. We focus on a practical scenario for cellular network where a single-antenna source is communicating to a multi-apertures destination through a relay equipped with multiple receive antennas and multiple transmit apertures. The RF single input multiple output (SIMO) links employ either maximal-ratio combining (MRC) or receive antenna selection (RAS), and the FSO multiple input multiple output (MIMO) links adopt either repetition coding (RC) or transmit laser selection (TLS). The performance is evaluated via an outage probability analysis over Rayleigh fading RF links and Gamma-Gamma atmospheric turbulence FSO links with pointing errors where channel state information (CSI) assisted amplify-and-forward (AF) scheme is considered. Asymptotic closed-form expressions at high signal-to-noise ratio (SNR) are also derived. Coding gain and diversity order for different combining and selection schemes are further discussed. Numerical results are provided to verify and illustrate the analytical results.

  18. Distributed Role Selection With ANC and TDBC Protocols in Two-Way Relaying Systems

    KAUST Repository

    Ding, Haiyang

    2015-09-28

    This paper advocates a distributed role selection strategy to coordinate two-way relaying transmissions among three cooperative nodes. For such, the local channel state information comparison and decision feedback mechanism are merged into classical analog network coding (ANC) and time division broadcast (TDBC) protocols such that the cooperative role of each node can be designated in a distributed fashion. We refer to this distributed role selection rule as d-ROSE. In both ANC-based and TDBC-based two-way relaying scenarios, strict proof for the equivalence of d-ROSE and optimal ROSE is given, which indicates that albeit the different form, their final role decision is essentially the same. Outage analysis for the d-ROSE strategy is carried out and the scaling law of the system outage behavior at high signal-to-noise ratio (SNR) is characterized, which manifests that d-ROSE can enhance the system diversity gain to one-order higher relative to the ANC and TDBC protocols. It is also shown that d-ROSE can reduce the signaling overhead upto 60% to perform the outage-optimal role selection. Finally, the impacts of node placement on the outage performance as well as the average signaling overhead of d-ROSE are numerically evaluated and some useful conclusions are drawn. © 2015 IEEE.

  19. Performance analysis of selective cooperation in amplify-and-forward relay networks over identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz; Alouini, Mohamed-Slim; Hasna, Mazen Omar

    2011-01-01

    In cooperative communications, multiple relays between a source and a destination can increase the diversity gain. Because all the nodes must use orthogonal channels, multiple-relay cooperation becomes spectrally inefficient. Therefore, a bestrelay selection scheme was recently proposed. In this paper, we analyzed the performance of this scheme for a system with the relays operating in amplify-and-forward mode over identical Nakagami-m channels using an exact source-relay-destination signal-to-noise ratio (SNR).We derived accurate closed-form expressions for various system parameters including the probability density function of end-to-end SNR, the average output SNR, the bit error probability, and the channel capacity. The analytical results were verified through Monte Carlo simulations. Copyright © 2011 John Wiley & Sons, Ltd.

  20. Efficiency Intra-Cluster Device-to-Device Relay Selection for Multicast Services Based on Combinatorial Auction

    Directory of Open Access Journals (Sweden)

    Yong Zhang

    2015-12-01

    Full Text Available In Long Term Evolution-Advanced (LTE-A networks, Device-to-device (D2D communications can be utilized to enhance the performance of multicast services by leveraging D2D relays to serve nodes with worse channel conditions within a cluster. For traditional D2D relay schemes, D2D links with poor channel condition may be the bottleneck of system sum data rate. In this paper, to optimize the throughput of D2D communications, we introduce an iterative combinatorial auction algorithm for efficient D2D relay selection. In combinatorial auctions, the User Equipments (UEs that fails to correctly receive multicast data from eNodeB (eNB are viewed as bidders that compete for D2D relays, while the eNB is treated as the auctioneer. We also give properties of convergency and low-complexity and present numerical simulations to verify the efficiency of the proposed algorithm.

  1. Outage probability of dual-hop partial relay selection with feedback delay in the presence of interference

    KAUST Repository

    Al-Qahtani, Fawaz S.

    2011-09-01

    In this paper, we investigate the outage performance of a dual-hop relaying systems with partial relay selection and feedback delay. The analysis considers the case of Rayleigh fading channels when the relaying station as well as the destination undergo mutually independent interfering signals. Particularly, we derive the cumulative distribution function (c.d.f.) of a new type of random variable involving sum of multiple independent exponential random variables, based on which, we present closed-form expressions for the exact outage probability of a fixed amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols. Numerical results are provided to illustrate the joint effect of the delayed feedback and co-channel interference on the outage probability. © 2011 IEEE.

  2. Performance analysis of selective cooperation in amplify-and-forward relay networks over identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2011-05-02

    In cooperative communications, multiple relays between a source and a destination can increase the diversity gain. Because all the nodes must use orthogonal channels, multiple-relay cooperation becomes spectrally inefficient. Therefore, a bestrelay selection scheme was recently proposed. In this paper, we analyzed the performance of this scheme for a system with the relays operating in amplify-and-forward mode over identical Nakagami-m channels using an exact source-relay-destination signal-to-noise ratio (SNR).We derived accurate closed-form expressions for various system parameters including the probability density function of end-to-end SNR, the average output SNR, the bit error probability, and the channel capacity. The analytical results were verified through Monte Carlo simulations. Copyright © 2011 John Wiley & Sons, Ltd.

  3. Minimax robust relay selection based on uncertain long-term CSI

    KAUST Repository

    Nisar, Muhammad Danish; Alouini, Mohamed-Slim

    2014-01-01

    Cooperative communications via multiple relay nodes is known to provide the benefits of increase diversity and coverage. Simultaneous transmission via multiple relays, however, requires strong coordination between nodes either in terms of slot

  4. Multiple Attribute Decision Making Based Relay Vehicle Selection for Electric Vehicle Communication

    Directory of Open Access Journals (Sweden)

    Zhao Qiang

    2015-01-01

    Full Text Available Large-scale electric vehicle integration into power grid and charging randomly will cause serious impacts on the normal operation of power grid. Therefore, it is necessary to control the charging behavior of electric vehicle, while information transmission for electric vehicle is significant. Due to the highly mobile characteristics of vehicle, transferring information to power grid directly might be inaccessible. Relay vehicle (RV can be used for supporting multi-hop connection between SV and power grid. This paper proposes a multiple attribute decision making (MADM-based RV selection algorithm, which considers multiple attribute, including data transfer rate, delay, route duration. It takes the characteristics of electric vehicle communication into account, which can provide protection for the communication services of electric vehicle charging and discharging. Numerical results demonstrate that compared to previous algorithm, the proposed algorithm offer better performance in terms of throughput, transmission delay.

  5. On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

    KAUST Repository

    Khafagy, Mohammad Galal; Ismail, Amr; Alouini, Mohamed-Slim; Aissa, Sonia

    2013-01-01

    expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

  6. Partial QoS-Aware Opportunistic Relay Selection Over Two-Hop Channels: End-to-End Performance Under Spectrum-Sharing Requirements

    KAUST Repository

    Yuli Yang,

    2014-10-01

    In this paper, we propose a partial quality-of-service (QoS)-oriented relay selection scheme with a decode-and-forward (DF) relaying protocol, to reduce the feedback amount required for relay selection. In the proposed scheme, the activated relay is the one with the maximum signal-to-noise power ratio (SNR) in the second hop among those whose packet loss rates (PLRs) in the first hop achieve a predetermined QoS level. For the purpose of evaluating the performance of the proposed scheme, we exploit it with transmission constraints imposed on the transmit power budget and interference to other users. By analyzing the statistics of received SNRs in the first and second hops, we obtain the end-to-end PLR of this scheme in closed form under the considered scenario. Moreover, to compare the proposed scheme with popular relay selection schemes, we also derive the closed-form PLR expressions for partial relay selection (PRS) and opportunistic relay selection (ORS) criteria in the same scenario under study. Illustrative numerical results demonstrate the accuracy of our derivations and substantiate that the proposed relay selection scheme is a promising alternative with respect to the tradeoff between performance and complexity.

  7. Toward distributed relay selection for opportunistic amplify-and-forward transmission

    KAUST Repository

    Tourki, Kamel; Alouini, Mohamed-Slim

    2011-01-01

    - noise ratios of the best relay. Furthermore, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures, and we compare our new results with their CSI

  8. Energy Harvesting-based Spectrum Access with Incremental Cooperation, Relay Selection and Hardware Noises

    Directory of Open Access Journals (Sweden)

    T. N. Nguyen

    2017-04-01

    Full Text Available In this paper, we propose an energy harvesting (EH-based spectrum access model in cognitive radio (CR network. In the proposed scheme, one of available secondary transmitters (STs helps a primary transmitter (PT forward primary signals to a primary receiver (PR. Via the cooperation, the selected ST finds opportunities to access licensed bands to transmit secondary signals to its intended secondary receiver (SR. Secondary users are assumed to be mobile, hence, optimization of energy consumption for these users is interested. The EH STs have to harvest energy from the PT's radio-frequency (RF signals to serve the PT-PR communication as well as to transmit their signals. The proposed scheme employs incremental relaying technique in which the PR only requires the assistance from the STs when the transmission between PT and PR is not successful. Moreover, we also investigate impact of hardware impairments on performance of the primary and secondary networks. For performance evaluation, we derive exact and lower-bound expressions of outage probability (OP over Rayleigh fading channel. Monte-Carlo simulations are performed to verify the theoretical results. The results present that the outage performance of both networks can be enhanced by increasing the number of the ST-SR pairs. In addition, it is also shown that fraction of time used for EH, positions of the secondary users and the hardware-impairment level significantly impact on the system performance.

  9. Bit Error-Rate Minimizing Detector for Amplify-and-Forward Relaying Systems Using Generalized Gaussian Kernel

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2013-01-01

    In this letter, a new detector is proposed for amplifyand- forward (AF) relaying system when communicating with the assistance of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the receiver. The probability density function is estimated with the help of kernel density technique. A generalized Gaussian kernel is proposed. This new kernel provides more flexibility and encompasses Gaussian and uniform kernels as special cases. The optimal window width of the kernel is calculated. Simulations results show that a gain of more than 1 dB can be achieved in terms of BER performance as compared to the minimum mean square error (MMSE) receiver when communicating over Rayleigh fading channels.

  10. Outage analysis of selective cooperation in underlay cognitive networks with fixed gain relays and primary interference modeling

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

    Selective cooperation is a well investigated technique in non-cognitive networks for efficient spectrum utilization and performance improvement. However, it is still a nascent topic for underlay cognitive networks. Recently, it was investigated for underlay networks where the secondary nodes were able to adapt their transmit power to always satisfy the interference threshold to the primary users. This is a valid assumption for cellular networks but many non-cellular devices have fixed transmit powers. In this situation, selective cooperation poses a more challenging problem and performs entirely differently. In this paper, we extend our previous work of selective cooperation based on either hop\\'s signal to noise ratio (SNR) with fixed gain and fixed transmit power relays in an underlay cognitive network. This work lacked in considering the primary interference over the cognitive network and presented a rather idealistic analysis. This paper deals with a more realistic system model and includes the effects of primary interference on the secondary transmission. We first derive end-to-end signal to interference and noise ratio (SINR) expression and the related statistics for a dual-hop relay link using asymptotic and approximate approaches. We then derive the statistics of the selected relay link based on maximum end-to-end SINR among the relays satisfying the interference threshold to the primary user. Using this statistics, we derive closed form asymptotic and approximate expressions for the outage probability of the system. Analytical results are verified through simulations. It is concluded that selective cooperation in underlay cognitive networks performs better only in low to medium SNR regions. © 2012 IEEE.

  11. Exact Throughput Analyses of Energy-Harvesting Cooperation Scheme with Best Relay Selections Under I/Q Imbalance

    Directory of Open Access Journals (Sweden)

    Tan Phuoc Huynh

    2017-01-01

    Full Text Available In this paper, we propose an energy-harvesting cooperation scheme in which relays suffer in-phase and quadrature-phase imbalances (IQI and harvest energy from a wireless transmit source. A best relay is selected based on end-to-end signal-to-interference-plus-noise ratios (SINRs in both Amplify-and-Forward (called an EHAF protocol and Decode-and-Forward (called an EHDF protocol cooperation methods. We analyze and evaluate the system performance in terms of exact closed-form throughputs over Rayleigh fading channels. Simulation and analysis results discover contributions as follows. Firstly, the throughput performance of the proposed protocols EHAF and EHDF is improved when comparing with that of a non-selection cooperation scheme. Secondly, the EHDF protocol is more efficient than the EHAF protocol. Finally, the theoretical analyses are validated by performing Monte Carlo simulations.

  12. BER analysis of multi-hop heterodyne FSO systems with fixed gain relays over general Malaga turbulence channels

    KAUST Repository

    Alheadary, Wael Ghazy

    2017-07-20

    This work investigates the end-to-end performance of a free space optical amplify-and-forward (AF) fixed-gain relaying system using heterodyne detection over misaligned general Malaga turbulence channels. More specifically, we present exact closed-form expressions for average bit-error rate achievable spectral efficiency non-adaptive/adaptive modulation schemes by employing generalized power series identity of Meijer\\'s G-function. Moreover, asymptotic closed-form expressions are derived to validate our results at high signal-to-noise ratio. In addition, the analytical results have been presented with compare to range of numerical values.

  13. BER analysis of multi-hop heterodyne FSO systems with fixed gain relays over general Malaga turbulence channels

    KAUST Repository

    Alheadary, Wael Ghazy; Park, Kihong; Alouini, Mohamed-Slim

    2017-01-01

    This work investigates the end-to-end performance of a free space optical amplify-and-forward (AF) fixed-gain relaying system using heterodyne detection over misaligned general Malaga turbulence channels. More specifically, we present exact closed-form expressions for average bit-error rate achievable spectral efficiency non-adaptive/adaptive modulation schemes by employing generalized power series identity of Meijer's G-function. Moreover, asymptotic closed-form expressions are derived to validate our results at high signal-to-noise ratio. In addition, the analytical results have been presented with compare to range of numerical values.

  14. Alternate MIMO relaying with three AF relays using interference alignment

    KAUST Repository

    Park, Kihong

    2012-06-01

    In this paper, we study a two-hop half-duplex relaying network with one source, one destination, and three amplify-and-forward (AF) relays equipped with M antennas each. We consider alternate transmission to compensate for the inherent loss of capacity pre-log factor 1/2 in half duplex mode, where source transmit message to two relays and the other relay alternately. The inter-relay interference caused by alternate transmission is aligned to make additional degrees of freedom (DOFs). It is shown that the proposed scheme enables us to exploit 3M/4 DOFs compared with the M/2 DOFs of conventional AF relaying. More specifically, suboptimal linear filter designs for a source and three relays are proposed to maximize the achievable sum-rate. We verify using some selected numerical results that the proposed filter designs give significant improvement of the sum-rate over a naive filter and conventional relaying schemes. © 2012 IEEE.

  15. Relay race

    CERN Multimedia

    Staff Association

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf

  16. Relay race

    CERN Document Server

    Staff Association

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12·15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf

  17. Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels †

    Science.gov (United States)

    Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

    2016-01-01

    In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source’s radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks. PMID:26927119

  18. Performance Evaluation of Relay Selection Schemes in Beacon-Assisted Dual-Hop Cognitive Radio Wireless Sensor Networks under Impact of Hardware Noises.

    Science.gov (United States)

    Hieu, Tran Dinh; Duy, Tran Trung; Dung, Le The; Choi, Seong Gon

    2018-06-05

    To solve the problem of energy constraints and spectrum scarcity for cognitive radio wireless sensor networks (CR-WSNs), an underlay decode-and-forward relaying scheme is considered, where the energy constrained secondary source and relay nodes are capable of harvesting energy from a multi-antenna power beacon (PB) and using that harvested energy to forward the source information to the destination. Based on the time switching receiver architecture, three relaying protocols, namely, hybrid partial relay selection (H-PRS), conventional opportunistic relay selection (C-ORS), and best opportunistic relay selection (B-ORS) protocols are considered to enhance the end-to-end performance under the joint impact of maximal interference constraint and transceiver hardware impairments. For performance evaluation and comparison, we derive the exact and asymptotic closed-form expressions of outage probability (OP) and throughput (TP) to provide significant insights into the impact of our proposed protocols on the system performance over Rayleigh fading channel. Finally, simulation results validate the theoretical results.

  19. Performance analysis of best relay selection scheme for amplify-and-forward cooperative networks in identical Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz; Alouini, Mohamed-Slim; Hasna, Mazen Omar

    2010-01-01

    for a cooperative network with multiple relays operating in amplify-and-forward (AF) mode over identical Nakagami-m channels using exact source-relay-destination signal to noise ratio (SNR) expression. We derive accurate closed form expressions

  20. Asymptotic Performance Analysis of Two-Way Relaying FSO Networks with Nonzero Boresight Pointing Errors Over Double-Generalized Gamma Fading Channels

    KAUST Repository

    Yang, Liang; Alouini, Mohamed-Slim; Ansari, Imran Shafique

    2018-01-01

    In this correspondence, an asymptotic performance analysis for two-way relaying free-space optical (FSO) communication systems with nonzero boresight pointing errors over double-generalized gamma fading channels is presented. Assuming amplify-and-forward (AF) relaying, two nodes having the FSO ability can communicate with each other through the optical links. With this setup, an approximate cumulative distribution function (CDF) expression for the overall signal-to-noise ratio (SNR) is presented. With this statistic distribution, we derive the asymptotic analytical results for the outage probability and average bit error rate. Furthermore, we provide the asymptotic average capacity analysis for high SNR by using the momentsbased method.

  1. Asymptotic Performance Analysis of Two-Way Relaying FSO Networks with Nonzero Boresight Pointing Errors Over Double-Generalized Gamma Fading Channels

    KAUST Repository

    Yang, Liang

    2018-05-07

    In this correspondence, an asymptotic performance analysis for two-way relaying free-space optical (FSO) communication systems with nonzero boresight pointing errors over double-generalized gamma fading channels is presented. Assuming amplify-and-forward (AF) relaying, two nodes having the FSO ability can communicate with each other through the optical links. With this setup, an approximate cumulative distribution function (CDF) expression for the overall signal-to-noise ratio (SNR) is presented. With this statistic distribution, we derive the asymptotic analytical results for the outage probability and average bit error rate. Furthermore, we provide the asymptotic average capacity analysis for high SNR by using the momentsbased method.

  2. Error-rate performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path can

  3. New results on performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

    2013-01-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may

  4. Accurate performance analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may

  5. Physical Layer Security for Cooperative Relaying Over Generalized-K Fading Channels

    KAUST Repository

    Wu, Ling; Yang, Liang; Chen, Jianchao; Alouini, Mohamed-Slim

    2018-01-01

    In this letter, we analyze the secrecy performance for a cooperative diversity system with amplify-and-forward (AF) over generalized-K fading channels. More specifically, some lower bounds on the secrecy performance, such as secure outage probability (SOP), average secrecy capacity (ASC), and strictly positive secrecy capacity (SPSC), are derived in closed-form. Finally, we provide simulation results to verify the accuracy of our analytical results.

  6. Physical Layer Security for Cooperative Relaying Over Generalized-K Fading Channels

    KAUST Repository

    Wu, Ling

    2018-02-02

    In this letter, we analyze the secrecy performance for a cooperative diversity system with amplify-and-forward (AF) over generalized-K fading channels. More specifically, some lower bounds on the secrecy performance, such as secure outage probability (SOP), average secrecy capacity (ASC), and strictly positive secrecy capacity (SPSC), are derived in closed-form. Finally, we provide simulation results to verify the accuracy of our analytical results.

  7. Generalized Selection Weighted Vector Filters

    Directory of Open Access Journals (Sweden)

    Rastislav Lukac

    2004-09-01

    Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

  8. Closeout of IE Bulletin 84-02: Failures of General Electric Type HFA relays in use in Class 1E safety systems

    International Nuclear Information System (INIS)

    Foley, W.J.; Dean, R.S.; Hennick, A.

    1991-01-01

    Documentation is provided in this report to close IE Bulletin 84--02 regarding the failure of General Electric Type HFA relays in Class 1E safety systems. The relay failures were due to aging of coil wire insulation and nylon or Lexan spools under certain environmental conditions. The bulletin was issued to nuclear power reactor licensees and holders of construction permits to provide assurance that the manufacturer's recommendations for corrective actions would be implemented. The bulletin required four specific actions, plus a review of the general concerns of the bulletin even though some facilities had different relays from those of bulletin concern. Evaluation of utility responses, NRC/Region inspection reports, and regional telephone calls has resulted in bulletin closeout of 116 (98%) of the 118 facilities to which the bulletin was issued for action. Facilities which were shut down or had construction halted indefinitely or permanently when the report was issued are not included in this review. A follow-up item is proposed in Appendix C for the two facilities with open status. Background information is supplied in the Introduction and Appendix A

  9. Target-specific NMR detection of protein–ligand interactions with antibody-relayed {sup 15}N-group selective STD

    Energy Technology Data Exchange (ETDEWEB)

    Hetényi, Anasztázia [University of Szeged, Department of Medical Chemistry (Hungary); Hegedűs, Zsófia [University of Szeged, SZTE-MTA Lendület Foldamer Research Group, Institute of Pharmaceutical Analysis Department (Hungary); Fajka-Boja, Roberta; Monostori, Éva [Biological Research Center of the Hungarian Academy of Sciences, Lymphocyte Signal Transduction Laboratory, Institute of Genetics (Hungary); Kövér, Katalin E. [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Martinek, Tamás A., E-mail: martinek@pharm.u-szeged.hu [University of Szeged, SZTE-MTA Lendület Foldamer Research Group, Institute of Pharmaceutical Analysis Department (Hungary)

    2016-12-15

    Fragment-based drug design has been successfully applied to challenging targets where the detection of the weak protein–ligand interactions is a key element. {sup 1}H saturation transfer difference (STD) NMR spectroscopy is a powerful technique for this work but it requires pure homogeneous proteins as targets. Monoclonal antibody (mAb)-relayed {sup 15}N-GS STD spectroscopy has been developed to resolve the problem of protein mixtures and impure proteins. A {sup 15}N-labelled target-specific mAb is selectively irradiated and the saturation is relayed through the target to the ligand. Tests on the anti-Gal-1 mAb/Gal-1/lactose system showed that the approach is experimentally feasible in a reasonable time frame. This method allows detection and identification of binding molecules directly from a protein mixture in a multicomponent system.

  10. Performance analysis of opportunistic nonregenerative relaying

    KAUST Repository

    Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.; Yang, Hongchuan

    2013-01-01

    Opportunistic relaying in cooperative communication depends on careful relay selection. However, the traditional centralized method used for opportunistic amplify-and-forward protocols requires precise measurements of channel state information at the destination. In this paper, we adopt the max-min criterion as a relay selection framework for opportunistic amplify-and-forward cooperative communications, which was exhaustively used for the decode-and-forward protocol, and offer an accurate performance analysis based on exact statistics of the local signal-to-noise ratios of the best relay. Furthermore, we evaluate the asymptotical performance and deduce the diversity order of our proposed scheme. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over Rayleigh fading channels, and we compare the max-min relay selection with their centralized channel state information-based and partial relay selection counterparts.

  11. Telecommunications Relay Services

    Science.gov (United States)

    ... Home » Health Info » Hearing, Ear Infections, and Deafness Telecommunications Relay Services On this page: What are telecommunication ... additional information about telecommunication relay services? What are telecommunication relay services? Title IV of the Americans with ...

  12. Frequency-selectivity of a thalamocortical relay neuron during Parkinson's disease and deep brain stimulation: a computational study

    NARCIS (Netherlands)

    Cagnan, Hayriye; Cagnan, H.; Meijer, Hil Gaétan Ellart; van Gils, Stephanus A.; Krupa, M.; Heida, Tjitske; Rudolph, Michelle; Wadman, Wyse J.; Martens, Hubert C.F.

    2009-01-01

    In this computational study, we investigated (i) the functional importance of correlated basal ganglia (BG) activity associated with Parkinson's disease (PD) motor symptoms by analysing the effects of globus pallidus internum (GPi) bursting frequency and synchrony on a thalamocortical (TC) relay

  13. Application of a proposed overcurrent relay in radial distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    Conde, A.; Vazquez, E. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, A.P. 36-F, CU, CP 66450, San Nicolas de los Garza, Nuevo Leon (Mexico)

    2011-02-15

    This paper contains the application criteria and coordination process for a proposed overcurrent relay in a radial power system with feed from one or multiple sources. This relay uses independent functions to detect faults and to calculate the operation time. Also this relay uses a time element function that allows it to reduce the time relay operation, enhancing the backup protection. Some of the proposed approaches improve the sensitivity of the relay. The selection of the best approach in the proposed relay is defined by the needs of the application. The proposed protection can be considered as an additional function protection to conventional overcurrent relays. (author)

  14. Control circuit for transformer relay

    International Nuclear Information System (INIS)

    Wyatt, G.A.

    1984-01-01

    A control circuit for a transformer relay which will automatically momentarily control the transformer relay to a selected state upon energization of the control circuit. The control circuit has an energy storage element and a current director coupled in series and adapted to be coupled with the secondary winding of the transformer relay. A device for discharge is coupled across the energy storage element. The energy storage element and current director will momentarily allow a unidirectional flow of current in the secondary winding of the transformer relay upon application of energy to the control circuit. When energy is not applied to the control circuit the device for discharge will allow the energy storage element to discharge and be available for another operation of the control circuit

  15. Electric equipment technical regulation on a relay

    International Nuclear Information System (INIS)

    1995-01-01

    It is about a relay for power protection. It describes the definitions of structure, a point of contact protection of contact, reclosing, relay scheme and input circuit. It explains normal use condition, special use condition, rated frequency, rated voltage and rated current, fluctuation range of permission of incoming relay. It deals with general structing outer case, correction device, operation indicator and outer terminal condition sort and method of the test. It adds the marks and pictures about currents

  16. Relay race

    CERN Multimedia

    Staff Association

    2012-01-01

    The CERN Relay Race will take place around the Meyrin site on Thursday 24th May at 12:00. This annual event is for teams of six runners covering distances of 1000 m, 800 m, 800 m, 500 m, 500 m and 300 m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. There will also this year be a Nordic Walking event, as part of the Medical Service’s initiative “Move more, eat better!” The registration fee is 10 CHF per runner, and each runner will receive a souvenir prize. There will be a programme of entertainment from 12:00 on the arrival area (the lawn in front of Restaurant 1): 12:00 - 12:45  Music from the Old Bottom Street band 12:15 Start of the race 12:45 - 13h Demonstrations by the Fitness club and Dancing club 13:00 Results and prize giving (including a raffle to win an iPad2 3G offered by the Micro club) 13:20 à 14:00 Music from “What’s next” And many information st...

  17. On the achievable degrees of freedom of alternate MIMO relaying with multiple AF relays

    KAUST Repository

    Park, Kihong

    2012-03-01

    In this paper, we consider a two-hop relaying network where one source, one destination, and multiple amplify-and-forward (AF) relays equipped with M antennas operate in a half-duplex mode. In order to compensate for the inherent loss of capacity pre-log factor of 1/2 due to half-duplex relaying, we propose a new transmission protocol which combines alternate relaying and inter-relay interference alignment. We prove that the proposed scheme can (i) exploits M degrees of freedom (DOFs) and (ii) perfectly recover the pre-log factor loss if the number of relays is at least six. From our selected numerical results, we show that our proposed scheme gives significant improvement over conventional AF relaying which offers only M/2 DOFs. © 2012 IEEE.

  18. Efficient incremental relaying

    KAUST Repository

    Fareed, Muhammad Mehboob; Alouini, Mohamed-Slim

    2013-01-01

    We propose a novel relaying scheme which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission

  19. Efficient incremental relaying

    KAUST Repository

    Fareed, Muhammad Mehboob

    2013-07-01

    We propose a novel relaying scheme which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying scheme with both amplify and forward and decode and forward relaying. Numerical results are also presented to verify their analytical counterparts. © 2013 IEEE.

  20. 80537 based distance relay

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen

    1999-01-01

    A method for implementing a digital distance relay in the power system is described.Instructions are given on how to program this relay on a 80537 based microcomputer system.The problem is used as a practical case study in the course 53113: Micocomputer applications in the power system.The relay...

  1. 47th Relay Race!

    CERN Document Server

    Staff Association

    2017-01-01

    On Thursday June 1st at 12.15, Fabiola Gianotti, our Director-General, will fire the starting shot for the 47th Relay Race. This Race is above all a festive CERN event, open for runners and walkers, as well as the people cheering them on throughout the race, and those who wish to participate in the various activities organised between 11.30 and 14.30 out on the lawn in front of Restaurant 1. In order to make this sports event accessible for everyone, our Director-General will allow for flexible lunch hours on the day, applicable for all the members of personnel. An alert for the closure of roads will be send out on the day of the event. The Staff Association and the CERN Running Club thank you in advance for your participation and your continued support throughout the years. This year the CERN Running Club has announced the participation of locally and internationally renowned runners, no less! A bit over a week from the Relay Race of 1st June, the number of teams is going up nicely (already almost 40). Am...

  2. Block compressed sensing for feedback reduction in relay-aided multiuser full duplex networks

    KAUST Repository

    Elkhalil, Khalil

    2016-08-11

    Opportunistic user selection is a simple technique that exploits the spatial diversity in multiuser relay-aided networks. Nonetheless, channel state information (CSI) from all users (and cooperating relays) is generally required at a central node in order to make selection decisions. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the presence of a full-duplex cooperating relay corrupts the fed back CSI by additive noise and the relay\\'s loop (or self) interference. This could lead to transmission outages if user selection is based on inaccurate feedback information. In this paper, we propose an opportunistic full-duplex feedback algorithm that tackles the above challenges. We cast the problem of joint user signal-to-noise ratio (SNR) and the relay loop interference estimation at the base-station as a block sparse signal recovery problem in compressive sensing (CS). Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated. Numerical results show that the proposed technique drastically reduces the feedback overhead and achieves a rate close to that obtained by techniques that require dedicated error-free feedback from all users. Numerical results also show that there is a trade-off between the feedback interference and load, and for short coherence intervals, full-duplex feedback achieves higher throughput when compared to interference-free (half-duplex) feedback. © 2016 IEEE.

  3. Spatially Controlled Relay Beamforming

    Science.gov (United States)

    Kalogerias, Dionysios

    layered channel model previously described, this line of research has resulted in a number of general, asymptotic convergence results, advancing the theory of grid-based approximate nonlinear stochastic filtering. In particular, sufficient conditions, ensuring asymptotic optimality are relaxed, and, at the same time, the mode of convergence is strengthened. Although the need for such results initiated as an attempt to theoretically characterize the performance of the proposed approximate methods for statistical inference, in regard to the proposed channel modeling approach, they turn out to be of fundamental importance in the areas of nonlinear estimation and stochastic control. The experimental validation of the proposed channel model, as well as the related parameter estimation problem, termed as "Markovian Channel Profiling (MCP)", fundamentally important for any practical deployment, are subject of current, ongoing research. Second, adopting the first of the two aforementioned channel modeling approaches, we consider the spatially controlled relay beamforming problem for an AF network with a single source, a single destination, and multiple, controlled at will, relay nodes. (Abstract shortened by ProQuest.).

  4. Opportunistic Fixed Gain Bidirectional Relaying with Outdated CSI

    KAUST Repository

    Khan, Fahd Ahmed; Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

    2015-01-01

    In a network with multiple relays, relay selection has been shown as an effective scheme to achieve diversity as well as to improve the overall throughput. This paper studies the impact of using outdated channel state information for relay selection on the performance of a network where two sources communicate with each other via fixed-gain amplify-and-forward relays. For a Rayleigh faded channel, closed-form expressions for the outage probability, moment generating function and symbol error rate are derived. Simulations results are also presented to corroborate the derived analytical results. It is shown that adding relays does not improve the performance if the channel is substantially outdated. Furthermore, relay location is also taken into consideration and it is shown that the performance can be improved by placing the relay closer to the source whose channel is more outdated. © 2015 IEEE.

  5. Opportunistic Fixed Gain Bidirectional Relaying with Outdated CSI

    KAUST Repository

    Khan, Fahd Ahmed

    2015-05-01

    In a network with multiple relays, relay selection has been shown as an effective scheme to achieve diversity as well as to improve the overall throughput. This paper studies the impact of using outdated channel state information for relay selection on the performance of a network where two sources communicate with each other via fixed-gain amplify-and-forward relays. For a Rayleigh faded channel, closed-form expressions for the outage probability, moment generating function and symbol error rate are derived. Simulations results are also presented to corroborate the derived analytical results. It is shown that adding relays does not improve the performance if the channel is substantially outdated. Furthermore, relay location is also taken into consideration and it is shown that the performance can be improved by placing the relay closer to the source whose channel is more outdated. © 2015 IEEE.

  6. CERN Relay Race

    CERN Document Server

    CERN Running Club

    2010-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 20 May, starting at 12.15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the route, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay

  7. Radioisotope relay instrument

    International Nuclear Information System (INIS)

    Pozdnyakov, V.N.; Sazonov, O.L.; Taksar, I.M.; Tesnavs, Eh.R.; Yanushkovskij, V.A.

    1974-01-01

    The paper describes a radioisotope relay device containing a radiation source, a detector, an electronic relay block with a comparative threshold mechanism. The device differs from previously known ones in that, for the purpose of increasing stability and speed of action, the electronic relay block is a separate unit and contains two threshold pulse generators which are joined up, across series-connected ''and'' and ''or'' elements, with one of the inputs of the comparative threshold mechanism, whose second input is connected with a detector and whose outputs are connected with a relay element connected by feedback with the above-mentioned ''and'' elements. (author)

  8. Outage analysis of selective cooperation in underlay cognitive networks with fixed gain relays and primary interference modeling

    KAUST Repository

    Hussain, Syed Imtiaz; Alouini, Mohamed-Slim; Qaraqe, Khalid A.; Hasna, Mazen Omar

    2012-01-01

    Selective cooperation is a well investigated technique in non-cognitive networks for efficient spectrum utilization and performance improvement. However, it is still a nascent topic for underlay cognitive networks. Recently, it was investigated

  9. Wheat (Triticum aestivum L. Cultivar Selection Affects Double-Crop and Relay-Intercrop Soybean (Glycine max L. Response on Claypan Soils

    Directory of Open Access Journals (Sweden)

    Kelly A. Nelson

    2010-01-01

    Full Text Available Field research (2003–2005 evaluated the effect of wheat row spacing (19 and 38 cm and cultivar on double-cropped (DC soybean response, 38-cm wheat on relay-intercrop (RI response, and wheat cultivar selection on gross margins of these cropping systems. Narrow-row wheat increased grain yield 460 kg ha−1, light interception (LI 7%, and leaf area index (LAI 0.5 compared to wide rows, but did not affect DC soybean yield. High yielding wheat (P25R37 with greater LI and LAI produced lower (330 kg ha−1 soybean yields in an RI system than a low yielding cultivar (Ernie. Gross margins were $267 ha−1 greater when P25R37 was RI with H431 Intellicoat (ITC soybean compared to Ernie. Gross margins were similar for monocrop H431 non-coated (NC or ITC soybean, P25R37 in 19- or 38-cm rows with DC H431 NC soybean, and P25R37 in 38-cm rows with RI H431 ITC soybean in the absence of an early fall frost.

  10. Coordinated Direct and Relay Transmission with Linear Non-Regenerative Relay Beamforming

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth; Popovski, Petar

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying, but also more general traffic scenarios, such as coordinated direct and relay (CDR) transmissions. In a CDR scheme the relay has a central...... role in managing the interference and boosting the overall system performance. In this letter we consider the case in which an amplify-and-forward relay has multiple antennas and can use beamforming to support the coordinated transmissions. We focus on one representative traffic type with one uplink...... user and one downlink user. Two different criteria for relay beamforming are analyzed: maximal weighted sum-rate and maximization of the worst-case weighted SNR. We propose iterative optimal solutions, as well as low-complexity near-optimal solutions....

  11. Exploring Relay Cooperation for Secure and Reliable Transmission in Two-HopWireless Networks

    Directory of Open Access Journals (Sweden)

    Yulong Shen

    2014-03-01

    Full Text Available This work considers the problem of secure and reliable information transmission via relay cooperation in two-hop relay wireless networks without the information of both eavesdropper channels and locations. While previous work on this problem mainly studied infinite networks and their asymptotic behavior and scaling law results, this papers focuses on a more practical network with finite number of system nodes and explores the corresponding exact result on the number of eavesdroppers one network can tolerate to ensure desired secrecy and reliability. We first study the scenario where path-loss is equal between all pairs of nodes and consider two transmission protocols there, one adopts an optimal but complex relay selection process with less load balance capacity while the other adopts a random but simple relay selection process with good load balance capacity. Theoretical analysis and numerical results are then provided to determine the maximum number of eavesdroppers one network can tolerate to ensure a desired performance in terms of the secrecy outage probability and transmission outage probability. We further extend our study to the more general scenario where path-loss between each pair of nodes also depends on the distance between them, for which a new transmission protocol with both preferable relay selection and good load balance as well as the corresponding theoretical analysis and numerical results are presented.

  12. Block compressed sensing for feedback reduction in relay-aided multiuser full duplex networks

    KAUST Repository

    Elkhalil, Khalil; Eltayeb, Mohammed; Kammoun, Abla; Al-Naffouri, Tareq Y.; Bahrami, Hamid Reza

    2016-01-01

    Opportunistic user selection is a simple technique that exploits the spatial diversity in multiuser relay-aided networks. Nonetheless, channel state information (CSI) from all users (and cooperating relays) is generally required at a central node in order to make selection decisions. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the presence of a full-duplex cooperating relay corrupts the fed back CSI by additive noise and the relay's loop (or self) interference. This could lead to transmission outages if user selection is based on inaccurate feedback information. In this paper, we propose an opportunistic full-duplex feedback algorithm that tackles the above challenges. We cast the problem of joint user signal-to-noise ratio (SNR) and the relay loop interference estimation at the base-station as a block sparse signal recovery problem in compressive sensing (CS). Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated. Numerical results show that the proposed technique drastically reduces the feedback overhead and achieves a rate close to that obtained by techniques that require dedicated error-free feedback from all users. Numerical results also show that there is a trade-off between the feedback interference and load, and for short coherence intervals, full-duplex feedback achieves higher throughput when compared to interference-free (half-duplex) feedback. © 2016 IEEE.

  13. Developing a Domain Model for Relay Circuits

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth

    2009-01-01

    In this paper we stepwise develop a domain model for relay circuits as used in railway control systems. First we provide an abstract, property-oriented model of networks consisting of components that can be glued together with connectors. This model is strongly inspired by a network model...... for railways madeby Bjørner et.al., however our model is more general: the components can be of any kind and can later be refined to e.g. railway components or circuit components. Then we show how the abstract network model can be refined into an explicit model for relay circuits. The circuit model describes...... the statics as well as the dynamics of relay circuits, i.e. how a relay circuit can be composed legally from electrical components as well as how the components may change state over time. Finally the circuit model is transformed into an executable model, and we show how a concrete circuit can be defined...

  14. Cooperative relay-based multicasting for energy and delay minimization

    KAUST Repository

    Atat, Rachad

    2012-08-01

    Relay-based multicasting for the purpose of cooperative content distribution is studied. Optimized relay selection is performed with the objective of minimizing the energy consumption or the content distribution delay within a cluster of cooperating mobiles. Two schemes are investigated. The first consists of the BS sending the data only to the relay, and the second scheme considers the scenario of threshold-based multicasting by the BS, where a relay is selected to transmit the data to the mobiles that were not able to receive the multicast data. Both schemes show significant superiority compared to the non-cooperative scenarios, in terms of energy consumption and delay reduction. © 2012 IEEE.

  15. Power system relaying

    CERN Document Server

    Horowitz, Stanley H; Niemira, James K

    2013-01-01

    The previous three editions of Power System Relaying offer comprehensive and accessible coverage of the theory and fundamentals of relaying and have been widely adopted on university and industry courses worldwide. With the third edition, the authors have added new and detailed descriptions of power system phenomena such as stability, system-wide protection concepts and discussion of historic outages. Power System Relaying, 4th Edition continues its role as an outstanding textbook on power system protection for senior and graduate students in the field of electric power engineering and a refer

  16. CERN Relay Race

    CERN Document Server

    2008-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 5 June starting at 12:15 p.m. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on how to register your team for the relay race are given on the Staff Association Bulletin web site. You can access the online registration form at: http://cern.ch/club-running-relay/form.html

  17. CERN Relay Race

    CERN Document Server

    2007-01-01

    The CERN relay race will take place around the Meyrin site on Wednesday 23 May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on how to register your team for the relay race are given on the Staff Association Bulletin web site. You can access the online registration form at: http://cern.ch/club-running-relay/form.html

  18. Ready, steady… relay!

    CERN Multimedia

    2008-01-01

    Thursday 5 June. With another year comes another success for CERN’s Relay Race. With 76 teams taking part it was the second highest turnout in the race’s history. ‘The Shabbys’ won the relay race in 10 minutes 51 seconds.As popular as ever, this year the relay race took on the atmosphere of a mini carnival. Gathering on the lawn outside Restaurant 1, various stalls and attractions added to the party feeling of the event, with beer courtesy of ‘AGLUP’, the Belgian beer club, and a wandering jazz group entertaining spectators and competitors alike. Reflecting the greater involvement of other associations in the relay race, the president of the Staff Association Clubs Committee, James Purvis, was the guest of honour, launching the start of the race and presenting the prizes. As regular followers of the race could have probably predicted, The Shabbys were once again victorious and claimed first place. The team members th...

  19. OPTIMASI OLSR ROUTING PROTOCOL PADA JARINGAN WIRELESS MESH DENGAN ADAPTIVE REFRESHING TIME INTERVAL DAN ENHANCE MULTI POINT RELAY SELECTING ALGORITHM

    Directory of Open Access Journals (Sweden)

    Faosan Mapa

    2014-01-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Wireless Mesh Network (WMN adalah suatu konektivitas jaringan yang self-organized, self-configured dan multi-hop. Tujuan dari WMN adalah menawarkan pengguna suatu bentuk jaringan nirkabel yang dapat dengan mudah berkomunikasi dengan jaringan konvensional dengan kecepatan tinggi dan dengan cakupan yang lebih luas serta biaya awal yang minimal. Diperlukan suatu desain protokol routing yang efisien untuk WMN yang secara adaptif dapat mendukung mesh routers dan mesh clients. Dalam tulisan ini, diusulkan untuk mengoptimalkan protokol OLSR, yang merupakan protokol routing proaktif. Digunakan heuristik yang meningkatkan protokol OLSR melalui adaptive refreshing time interval dan memperbaiki metode MPR selecting algorithm. Suatu analisa dalam meningkatkan protokol OLSR melalui adaptive refreshing time interval dan memperbaiki algoritma pemilihan MPR menunjukkan kinerja yang signifikan dalam hal throughput jika dibandingkan dengan protokol OLSR yang asli. Akan tetapi, terdapat kenaikan dalam hal delay. Pada simulasi yang dilakukan dapat disimpulkan bahwa OLSR dapat dioptimalkan dengan memodifikasi pemilihan node MPR berdasarkan cost effective dan penyesuaian waktu interval refreshing hello message sesuai dengan keadaan

  20. Subset selection from generalized logistic populations

    NARCIS (Netherlands)

    Laan, van der M.J.; Laan, van der P.

    1997-01-01

    We give an introduction to the logistic and generalized logistic distributions. These generalized logistic distributions Type-I, Type-II and Type-III are indexed by a real valued parameter. They have been derived as mixtures with the standard logistic distribution and for discrete values of the

  1. Impact of Co-Channel Interference on the Outage Performance Under Multiple Type II Relay Environments

    KAUST Repository

    Choi, Seyeong; Alouini, Mohamed-Slim; Nam, Sung Sik

    2017-01-01

    In this paper, through an exact analysis of the outage probability, we investigate the impact of co-channel interference (CCI) on the outage performance of type II (or user equipment) relay under multiple-relay environments considering the selection combining-based relay selection scheme with the decode-and-forward protocol. We consider the signal to interference plus noise ratio (SINR) over both independent and identically distributed and independent but non-identically distributed fading channels. To fully take into account the effect of CCI, we adopt a more practical parameter such as the CCI coefficient. The major difficulty in the analysis resides in the determination of the statistics of the output SINR. To settle this problem, we first present the general but relatively simplified expressions for the statistics and then the related outage probability in closed-form. Furthermore, to consider more practical scenario, based on the fact that the number of participating relays can be random, we investigate the average outage probability by averaging the number of participating relays.

  2. Impact of Co-Channel Interference on the Outage Performance Under Multiple Type II Relay Environments

    KAUST Repository

    Choi, Seyeong

    2017-11-15

    In this paper, through an exact analysis of the outage probability, we investigate the impact of co-channel interference (CCI) on the outage performance of type II (or user equipment) relay under multiple-relay environments considering the selection combining-based relay selection scheme with the decode-and-forward protocol. We consider the signal to interference plus noise ratio (SINR) over both independent and identically distributed and independent but non-identically distributed fading channels. To fully take into account the effect of CCI, we adopt a more practical parameter such as the CCI coefficient. The major difficulty in the analysis resides in the determination of the statistics of the output SINR. To settle this problem, we first present the general but relatively simplified expressions for the statistics and then the related outage probability in closed-form. Furthermore, to consider more practical scenario, based on the fact that the number of participating relays can be random, we investigate the average outage probability by averaging the number of participating relays.

  3. CERN Relay Race 2009

    CERN Document Server

    2009-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 14th May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. More details on how to register your team for the relay race

  4. CERN Relay Race

    CERN Document Server

    2006-01-01

    The CERN relay race will take place around the Meyrin site on Wednesday 17 May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Details on how to register your team for the relay race are given on the Staff Association Bulletin web site.

  5. Modular relay control

    OpenAIRE

    Ivarsson, Mikael

    2010-01-01

    Enics Sweden AB, Västerås, is an electronics manufacturing services company with its main business in manufacturing electronics. Most, if not all, electronic devices that are manufactured are being widely tested before delivery to ensure proper functionality. Often during tests a large number of signals are measured by one to a few digital multimeters and are therefore controlled through relays. Relays are also used when applying stimuli with high currents or voltages to the unit under test. ...

  6. An assessment of fire vulnerability for aged electrical relays

    International Nuclear Information System (INIS)

    Vigil, R.A.; Nowlen, S.P.

    1995-03-01

    There has been some concern that, as nuclear power plants age, protective measures taken to control and minimize the impact of fire may become ineffective, or significantly less effective, and hence result in an increased fire risk. One objective of the Fire Vulnerability of Aged Electrical Components Program is to assess the effects of aging and service wear on the fire vulnerability of electrical equipment. An increased fire vulnerability of components may lead to an overall increase in fire risk to the plant. Because of their widespread use in various electrical safety systems, electromechanical relays were chosen to be the initial components for evaluation. This test program assessed the impact of operational and thermal aging on the vulnerability of these relays to fire-induced damage. Only thermal effects of a fire were examined in this test program. The impact of smoke, corrosive materials, or fire suppression effects on relay performance were not addressed in this test program. The purpose of this test program was to assess whether the fire vulnerability of electrical relays increased with aging. The sequence followed for the test program was to: identify specific relay types, develop three fire scenarios, artificially age several relays, test the unaged and aged relays in the fire exposure scenarios, and compare the results. The relays tested were Agastat GPI, General Electric (GE) HMA, HGA, and HFA. At least two relays of each type were artificially aged and at least two relays of each type were new. Relays were operationally aged by cycling the relay under rated load for 2,000 operations. These relays were then thermally aged for 60 days with their coil energized

  7. Performance analysis of two-way amplify and forward relaying with adaptive modulation over multiple relay network

    KAUST Repository

    Hwang, Kyusung

    2011-02-01

    In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements. © 2011 IEEE.

  8. Performance analysis of two-way amplify and forward relaying with adaptive modulation over multiple relay network

    KAUST Repository

    Hwang, Kyusung; Ko, Youngchai; Alouini, Mohamed-Slim

    2011-01-01

    In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements. © 2011 IEEE.

  9. End-to-end performance of cooperative relaying in spectrum-sharing systems with quality of service requirements

    KAUST Repository

    Asghari, Vahid Reza

    2011-07-01

    We propose adopting a cooperative relaying technique in spectrum-sharing cognitive radio (CR) systems to more effectively and efficiently utilize available transmission resources, such as power, rate, and bandwidth, while adhering to the quality of service (QoS) requirements of the licensed (primary) users of the shared spectrum band. In particular, we first consider that the cognitive (secondary) user\\'s communication is assisted by an intermediate relay that implements the decode-and-forward (DF) technique onto the secondary user\\'s relayed signal to help with communication between the corresponding source and the destination nodes. In this context, we obtain first-order statistics pertaining to the first- and second-hop transmission channels, and then, we investigate the end-to-end performance of the proposed spectrum-sharing cooperative relaying system under resource constraints defined to assure that the primary QoS is unaffected. Specifically, we investigate the overall average bit error rate (BER), ergodic capacity, and outage probability of the secondary\\'s communication subject to appropriate constraints on the interference power at the primary receivers. We then consider a general scenario where a cluster of relays is available between the secondary source and destination nodes. In this case, making use of the partial relay selection method, we generalize our results for the single-relay scheme and obtain the end-to-end performance of the cooperative spectrum-sharing system with a cluster of L available relays. Finally, we examine our theoretical results through simulations and comparisons, illustrating the overall performance of the proposed spectrum-sharing cooperative system and quantify its advantages for different operating scenarios and conditions. © 2011 IEEE.

  10. Cooperative relay-based multicasting for energy and delay minimization

    KAUST Repository

    Atat, Rachad; Yaacoub, Elias E.; Alouini, Mohamed-Slim; Abu-Dayya, Adnan A.

    2012-01-01

    mobiles. Two schemes are investigated. The first consists of the BS sending the data only to the relay, and the second scheme considers the scenario of threshold-based multicasting by the BS, where a relay is selected to transmit the data to the mobiles

  11. Relay test program

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.K.; Kunkel, C.; Shteyngart, S.

    1994-02-01

    This report presents the results of a relay test program conducted by Brookhaven National Laboratory (BNL) under the sponsorship of the US Nuclear Regulatory Commission (NRC). The program is a continuation of an earlier test program the results of which were published in NUREG/CR-4867. The current program was carried out in two phases: electrical testing and vibration testing. The objective was primarily to focus on the electrical discontinuity or continuity of relays and circuit breaker tripping mechanisms subjected to electrical pulses and vibration loads. The electrical testing was conducted by KEMA-Powertest Company and the vibration testing was performed at Wyle Laboratories, Huntsville, Alabama. This report discusses the test procedures, presents the test data, includes an analysis of the data and provides recommendations regarding reliable relay testing

  12. CERN Relay Race

    CERN Multimedia

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19 May starting at 12-15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details of the course and of how to register your team for the relay race can be found here. Some advice for all runners from the Medical Service can also be found here.   

  13. Mapping selected general literature of international nursing.

    Science.gov (United States)

    Shams, Marie-Lise Antoun; Dixon, Lana S

    2007-01-01

    This study, part of a wider project to map the literature of nursing, identifies core journals cited in non-US nursing journals and determines the extent of their coverage by indexing services. Four general English-language journals were analyzed for format types and publication dates. Core titles were identified and nine bibliographic databases were scanned for indexing coverage. Findings show that 57.5% (13,391/23,271) of the cited references from the 4 core journals were to journal articles, 27.8% (6,471/23,271) to books, 9.5% (2,208/23,271) to government documents, 4.9% (1,131/23,271) to miscellaneous sources, and less than 1% (70/23,271) to Internet resources. Eleven journals produced one-third of the citations; the next third included 146 journals, followed by a dispersion of 1,622 titles. PubMed received the best database coverage scores, followed by CINAHL and Science Citation Index. None of the databases provided complete coverage of all 11 core titles. The four source journals contain a diverse group of cited references. The currency of citations to government documents makes these journals a good source for regulatory and legislative awareness. Nurses consult nursing and biomedical journals and must search both nursing and biomedical databases to cover the literature.

  14. CERN Relay Race

    CERN Multimedia

    2004-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday 19 May between 12.15 and 12.35. If possible, please avoid driving on the site during this 20 minute period. If you do meet runners in your car, please STOP until they all have passed. Thank you for your understanding

  15. CERN Relay Race

    CERN Multimedia

    2003-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday May 21st between 12h15 and 12h35. If possible, please avoid driving on the site during this 20 minute period. If you do meet runners in your car, please STOP until they all have passed. Thank you for your understanding

  16. CERN Relay Race

    CERN Multimedia

    2001-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday 23 May between 12:20 and 12:35. If possible, please avoid driving on the site during this 15 minute period. If you do meet runners in your car, please stop until they all have passed. Thank you for your understanding.

  17. CERN Relay Race

    CERN Document Server

    2002-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday 22 May between 12h20 and 12h35. If possible, please avoid driving on the site during this 15 minute period. If you do meet runners in your car, please STOP until they all have passed. Thank you for your understanding.

  18. CERN Relay Race

    CERN Multimedia

    2009-01-01

    The CERN relay race, now in its 39th year, is already a well-known tradition, but this year the organizers say the event will have even more of a festival feeling. Just off the starting line of the CERN relay race.For the past few years, spectators and runners at the CERN relay race have been able to enjoy a beer while listening to music from the CERN music and jazz clubs. But this year the organizers are aiming for "even more of a festival atmosphere". As David Nisbet, President of the CERN running club and organizer of the relay race, says: "Work is not just about getting your head down and doing the theory, it’s also about enjoying the company of your colleagues." This year, on top of music from the Santa Luis Band and the Canettes Blues Band, there will be demonstrations from the Aikido and softball clubs, a stretching session by the Fitness club, as well as various stalls and of course, the well-earned beer from AGLUP, the B...

  19. 2005 CERN Relay Race

    CERN Multimedia

    Patrice Loiez

    2005-01-01

    The CERN Relay Race takes place each year in May and sees participants from all areas of the CERN staff. The winners in 2005 were The Shabbys with Los Latinos Volantes in second and Charmilles Technologies a close third. To add a touch of colour and levity, the CERN Jazz Club provided music at the finishing line.

  20. Performance of amplify-and-forward multihop transmission over relay clusters with different routing strategies

    KAUST Repository

    Yilmaz, Ferkan; Khan, Fahd Ahmed; Alouini, Mohamed-Slim

    2014-01-01

    We consider a multihop relay network in which two terminals are communicating with each other via a number of cluster of relays. Performance of such networks depends on the routing protocols employed. In this paper, we find the expressions for the Average Symbol Error Probability (ASEP) performance of Amplify-and-Forward (AF) multihop transmission for the simplest routing protocol in which the relay transmits using the channel having the best Signal to Noise Ratio (SNR). The ASEP performance of a better protocol proposed in Gui et al. (2009) known as the adhoc protocol is also analyzed. The derived expressions for the performance are a convenient tool to analyze the performance of AF multihop transmission over relay clusters. Monte-Carlo simulations verify the correctness of the proposed formulation and are in agreement with analytical results. Furthermore, we propose new generalized protocols termed as last-nhop selection protocol, the dual path protocol, the forward-backward last-n-hop selection protocol and the forward-backward dual path protocol, to get improved ASEP performances. The ASEP performance of these proposed schemes is analysed by computer simulations. It is shown that close to optimal performance can be achieved by using the last-n-hop selection protocol and its forwardbackward variant. The complexity of the protocols is also studied. Copyright © 2014 Inderscience Enterprises Ltd.

  1. On Buffer-Aided Multiple-Access Relay Channel

    DEFF Research Database (Denmark)

    Liu, Rongkuan; Popovski, Petar; Wang, Gang

    2016-01-01

    This letter treats uplink scenario where M user equipments (UEs) send to a base station (BS), possibly via a common relay station (RS) that is equipped with a buffer. This is a multiple-access relay channel aided by a buffer. We devise a protocol in which the transmission mode is selected...... entirely at the BS, while simultaneously a number of UEs sends new messages to the BS. The results show that the adaptive selection of direct and buffer-aided relay transmissions leads to significant average throughput gains....

  2. OPRA capacity bounds for selection diversity over generalized fading channels

    KAUST Repository

    Hanif, Muhammad Fainan; Yang, Hongchuan; Alouini, Mohamed-Slim

    2014-01-01

    , lower and upper bounds on OPRA capacity for selection diversity scheme are presented. These bounds hold for variety of fading channels including log-normal and generalized Gamma distributed models and have very simple analytic expressions for easy

  3. Site selection and general layout of heap leaching uranium mill

    International Nuclear Information System (INIS)

    Zhang Chunmao; Rongfeng

    2011-01-01

    The site selection and general layout of uranium mill is an important work in the design and consultation stage of uranium mining and metallurgy's engineering construction. Based on the design practices, the principles and methods for the site selection and general layout of heap leaching uranium mill are analyzed and studied. Some problems which should be paid much attention to in the design are discussed in hopes of providing a useful reference for the design and consultation of similar projects. (authors)

  4. Implementation of a Relay Coordination System for the Mars Network

    Science.gov (United States)

    Allard, Daniel A.

    2010-01-01

    Mars network relay operations involve the coordination of lander and orbiter teams through long-term and short-term planning, tactical changes and post-pass analysis. Much of this coordination is managed through email traffic and point-to-point file data exchanges. It is often difficult to construct a complete and accurate picture of the relay situation at any given moment, as there is no centralized store of correlated relay data. The Mars Relay Operations Service (MaROS) is being implemented to address the problem of relay coordination for current and next-generation relay missions. The service is provided for the purpose of coordinating communications sessions between landed spacecraft assets and orbiting spacecraft assets at Mars. The service centralizes a set of functions previously distributed across multiple spacecraft operations teams, and as such greatly improves visibility into the end-to-end strategic coordination process. Most of the process revolves around the scheduling of communications sessions between the spacecraft during periods of time when a landed asset on Mars is geometrically visible by an orbiting spacecraft. These "relay" sessions are used to transfer data both to and from the landed asset via the orbiting asset on behalf of Earth-based spacecraft operators. This paper will discuss the relay coordination problem space, overview the architecture and design selected to meet system requirements, and describe the first phase of system implementation

  5. Sum-Rate Maximization of Coordinated Direct and Relay Systems

    DEFF Research Database (Denmark)

    Sun, Fan; Popovski, Petar; Thai, Chan

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying based on wireless network coding. Recently, a related set of techniques has emerged, termed coordinated direct and relay (CDR) transmissions......, where the constellation of traffic flows is more general than the two-way. Regardless of the actual traffic flows, in a CDR scheme the relay has a central role in managing the interference and boosting the overall system performance. In this paper we investigate the novel transmission modes, based...... on amplify-and-forward, that arise when the relay is equipped with multiple antennas and can use beamforming. We focus on one representative traffic type, with one uplink and one downlink users and consider the achievable sum-rate maximization relay beamforming. The beamforming criterion leads to a non...

  6. Beamforming Design for Coordinated Direct and Relay Systems

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth; Thai, Chan

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying based on wireless network coding. Recently, a related set of techniques has emerged, termed coordinated direct and relay (CDR) transmissions......, where the constellation of traffic flows is more general than the two-way. Regardless of the actual traffic flows, in a CDR scheme the relay has a central role in managing the interference. In this paper we investigate the novel transmission modes, based on amplify-and-forward, that arise when the relay...... an iterative solution, as well as derive an upper performance bound. The numerical results demonstrate a clear benefit from usage of multiple antennas at the relay node....

  7. MaROS Strategic Relay Planning and Coordination Interfaces

    Science.gov (United States)

    Allard, Daniel A.

    2010-01-01

    The Mars Relay Operations Service (MaROS) is designed to provide planning and analysis tools in support of ongoing Mars Network relay operations. Strategic relay planning requires coordination between lander and orbiter mission ground data system (GDS) teams to schedule and execute relay communications passes. MaROS centralizes this process, correlating all data relevant to relay coordination to provide a cohesive picture of the relay state. Service users interact with the system through thin-layer command line and web user interface client applications. Users provide and utilize data such as lander view periods of orbiters, Deep Space Network (DSN) antenna tracks, and reports of relay pass performance. Users upload and download relevant relay data via formally defined and documented file structures including some described in Extensible Markup Language (XML). Clients interface with the system via an http-based Representational State Transfer (ReST) pattern using Javascript Object Notation (JSON) formats. This paper will provide a general overview of the service architecture and detail the software interfaces and considerations for interface design.

  8. Alternate MIMO relaying with three AF relays using interference alignment

    KAUST Repository

    Park, Kihong; Alouini, Mohamed-Slim

    2012-01-01

    In this paper, we study a two-hop half-duplex relaying network with one source, one destination, and three amplify-and-forward (AF) relays equipped with M antennas each. We consider alternate transmission to compensate for the inherent loss

  9. New results on performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-12-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may be unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the selected relay. We first derive the signal-to-noise (SNR) statistics for each hop, which are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation and end-to-end outage probability for a transmission rate R over Rayleigh fading channels. Furthermore, we evaluate the asymptotical performance and deduce the diversity order. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network architecture. © 2013 Elsevier B.V.

  10. Error-rate performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2011-09-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path can be considered unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We first derive the exact statistics of each hop, in terms of probability density function (PDF). Then, the PDFs are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation where the detector may use maximum ration combining (MRC) or selection combining (SC). Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network (LN) architecture and considering Rayleigh fading channels. © 2011 IEEE.

  11. Joint source and relay optimization for interference MIMO relay networks

    Science.gov (United States)

    Khandaker, Muhammad R. A.; Wong, Kai-Kit

    2017-12-01

    This paper considers multiple-input multiple-output (MIMO) relay communication in multi-cellular (interference) systems in which MIMO source-destination pairs communicate simultaneously. It is assumed that due to severe attenuation and/or shadowing effects, communication links can be established only with the aid of a relay node. The aim is to minimize the maximal mean-square-error (MSE) among all the receiving nodes under constrained source and relay transmit powers. Both one- and two-way amplify-and-forward (AF) relaying mechanisms are considered. Since the exactly optimal solution for this practically appealing problem is intractable, we first propose optimizing the source, relay, and receiver matrices in an alternating fashion. Then we contrive a simplified semidefinite programming (SDP) solution based on the error covariance matrix decomposition technique, avoiding the high complexity of the iterative process. Numerical results reveal the effectiveness of the proposed schemes.

  12. OPRA capacity bounds for selection diversity over generalized fading channels

    KAUST Repository

    Hanif, Muhammad Fainan

    2014-05-01

    Channel side information at the transmitter can increase the average capacity by enabling optimal power and rate adaptation. The resulting optimal power and rate adaptation (OPRA) capacity rarely has a closed-form analytic expression. In this paper, lower and upper bounds on OPRA capacity for selection diversity scheme are presented. These bounds hold for variety of fading channels including log-normal and generalized Gamma distributed models and have very simple analytic expressions for easy evaluation even for kth best path selection. Some selected numerical results show that the newly proposed bounds closely approximate the actual OPRA capacity. © 2014 IEEE.

  13. CERN Relay Race 2018

    CERN Document Server

    CERN Running club

    2018-01-01

    The CERN running club, in collaboration with the Staff Association, is happy to announce the 2018 relay race edition. It will take place on Thursday, May 24th and will consist as every year in a round trip of the CERN Meyrin site in teams of 6 members. It is a fun event, and you do not have to run fast to enjoy it. Registrations will be open from May 1st to May 22nd on the running club web site. All information concerning the race and the registration are available there too: http://runningclub.web.cern.ch/content/cern-relay-race. A video of the previous edition is also available here : http://cern.ch/go/Nk7C. As every year, there will be animations starting at noon on the lawn in front of restaurant 1, and information stands for many CERN associations and clubs will be available. The running club partners will also be participate in the event, namely Berthie Sport, Interfon and Uniqa.

  14. CERN Relay Race

    CERN Multimedia

    Running Club

    2010-01-01

    This year’s CERN Relay Race will take place around the Meyrin site on Thursday 20th May at 12h00. This annual event is for teams of 6 runners covering distances of 1000m, 800m, 800m, 500m, 500m and 300m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. The registration fee is 10 CHF per runner, and each runner receives a souvenir prize. As usual, there will be a programme of entertainments from 12h in the arrival area, in front of the Restaurant no. 1. Drinks, food, CERN club information and music will be available for the pleasure of both runners and spectators. The race starts at 12h15, with results and prize giving at 13:15.   For details of the race, and of how to sign up a team, please visit: https://espace.cern.ch/Running-Club/CERN-Relay The event is organised by the CERN Running Club with the support of the CERN Staff Association.  

  15. Relays undergo seismic tests

    International Nuclear Information System (INIS)

    Burton, J.C.

    1977-01-01

    Utilities are required by the Nuclear Regulatory Commission to document that seismic vibration will not adversely affect critical electrical equipment. Seismic testing should be designed to determine the malfunction level (fragility testing). Input possibilities include a continuous sine, a decaying sine, a sine beat, random vibrations, and combinations of random vibrations and sine beat. The sine beat most accurately simulates a seismic event. Test frequencies have a broad range in order to accommodate a variety of relay types and cabinet mounting. Simulation of motion along three axes offers several options, but is best achieved by three in-phase single-axis vibration machines that are less likely to induce testing fatigue failure. Consensus on what constitutes relay failure favors a maximum two microsecond discontinuity. Performance tests should be conducted for at least two of the following: (1) nonoperating modes, (2) operating modes, or (3) the transition above the two modes, with the monitoring mode documented for all three. Results should specify a capability curve of maximum safe seismic acceleration and a graph plotting acceleration with sine-beat frequency

  16. On polynomial selection for the general number field sieve

    Science.gov (United States)

    Kleinjung, Thorsten

    2006-12-01

    The general number field sieve (GNFS) is the asymptotically fastest algorithm for factoring large integers. Its runtime depends on a good choice of a polynomial pair. In this article we present an improvement of the polynomial selection method of Montgomery and Murphy which has been used in recent GNFS records.

  17. MIMO Four-Way Relaying

    DEFF Research Database (Denmark)

    Liu, Huaping; Sun, Fan; De Carvalho, Elisabeth

    2013-01-01

    Two-way relaying in wireless systems has initiated a large research effort during the past few years. Nevertheless, it represents only a specific traffic pattern and it is of interest to investigate other traffic patterns where such a simultaneous processing of information flows can bring...... performance advantage. In this paper we consider a \\emph{four-way relaying} multiple-input multiple-output (MIMO) scenario, where each of the two Mobile Stations (MSs) has a two-way connection to the same Base Station (BS), while each connection is through a dedicated Relay Station (RS). The RSs are placed...... the sum-rate of the new scheme for Decode-and-Forward (DF) operational model for the RS. We compare the performance with state-of-the-art reference schemes, based on two-way relaying with DF. The results indicate that the sum-rate of the two-phase four-way relaying scheme largely outperforms the four...

  18. Synthesis of relay control systems for nuclear reactors

    International Nuclear Information System (INIS)

    Postnikov, N.S.

    1996-01-01

    The problem on stabilizing an oscillatory-unstable reactor by a single-link relay system, the characteristics whereof have a dead zone and hysteresis loop, is considered. The methodology of synthesis of feedback law, providing for stochastic steady-state mode of reactor operation with the minimum frequency of control impact introduction is proposed. This methodology is applicable to general-type relay systems with arbitrary oscillatory-unstable objects. 6 refs., 5 figs

  19. Outage performance of opportunistic two-way amplify-and-forward relaying with outdated channel state information

    KAUST Repository

    Hwang, Kyusung; Ju, Minchul; Alouini, Mohamed-Slim

    2013-01-01

    In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we

  20. Linear Processing Design of Amplify-and-Forward Relays for Maximizing the System Throughput

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2018-01-01

    Full Text Available In this paper, firstly, we study the linear processing of amplify-and-forward (AF relays for the multiple relays multiple users scenario. We regard all relays as one special “relay”, and then the subcarrier pairing, relay selection and channel assignment can be seen as a linear processing of the special “relay”. Under fixed power allocation, the linear processing of AF relays can be regarded as a permutation matrix. Employing the partitioned matrix, we propose an optimal linear processing design for AF relays to find the optimal permutation matrix based on the sorting of the received SNR over the subcarriers from BS to relays and from relays to users, respectively. Then, we prove the optimality of the proposed linear processing scheme. Through the proposed linear processing scheme, we can obtain the optimal subcarrier paring, relay selection and channel assignment under given power allocation in polynomial time. Finally, we propose an iterative algorithm based on the proposed linear processing scheme and Lagrange dual domain method to jointly optimize the joint optimization problem involving the subcarrier paring, relay selection, channel assignment and power allocation. Simulation results illustrate that the proposed algorithm can achieve a perfect performance.

  1. Information-guided transmission in decode-and-forward relaying systems: Spatial exploitation and throughput enhancement

    KAUST Repository

    Yang, Yuli

    2011-07-01

    In addressing the issue of achieving high throughput in half-duplex relay channels, we exploit a concept of information-guided transmission for the network consisting of a source node, a destination node, and multiple half-duplex relay nodes. For further benefiting from multiple relay nodes, the relay-selection patterns are defined as the arbitrary combinations of given relay nodes. By exploiting the difference among the spatial channels states, in each relay-help transmission additional information to be forwarded is mapped onto the index of the active relay-selection pattern besides the basic information mapped onto the traditional constellation, which is forwarded by the relay node(s) in the active relay-selection pattern, so as to enhance the relay throughtput. With iterative decoding, the destination node can achieve a robust detection by decoupling the signals forwarded in different ways. We investigate the proposed scheme considering "decode-and-forward" protocol and establish its achievable transmission rate. The analytical results on capacity behaviors prove the efficiency of the proposed scheme by showing that it achieves better capacity performance than the conventional scheme. © 2011 IEEE.

  2. CERN Relay Race

    CERN Document Server

    2005-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday 18 May between 12.15 and 12.35. This year, weather permitting, there will be some new attractions in the start/finish area on the field behind the Main Building. You will be able to: listen to music played by the CERN Jazz Club; buy drinks at the bar organised by the CERN Running Club; buy lunch served directly on the terrace by the restaurant Novae. ATTENTION: concerning traffic, the recommendations are the same as always: If possible, please avoid driving on the site during this 20 minute period. If you do meet runners in your car, please STOP until they all have passed. Thank you for your understanding.

  3. Voz sobre frame relay

    OpenAIRE

    D´Elia, Gabriel Anibal

    2000-01-01

    Esta tesis trata el tema de VOFR, desde la digitalización de la voz hasta su transmisión a través de dicha red, así también como la comparación con otros medios de transporte como VOIP. Dada las características del protocolo frame relay y su disponibilidad se eligió como el medio más apropiado para la transmisión de voz y datos en forma integrada sobre una misma red. El trabajo comienza con una breve explicación de la voz, su digitalización y forma actual de transmisión a través de una red di...

  4. Relay entanglement and clusters of correlated spins

    Science.gov (United States)

    Doronin, S. I.; Zenchuk, A. I.

    2018-06-01

    Considering a spin-1/2 chain, we suppose that the entanglement passes from a given pair of particles to another one, thus establishing the relay transfer of entanglement along the chain. Therefore, we introduce the relay entanglement as a sum of all pairwise entanglements in a spin chain. For more detailed studying the effects of remote pairwise entanglements, we use the partial sums collecting entanglements between the spins separated by up to a certain number of nodes. The problem of entangled cluster formation is considered, and the geometric mean entanglement is introduced as a characteristic of quantum correlations in a cluster. Generally, the lifetime of a cluster decreases with an increase in its size.

  5. STUDI ANALISIS KOORDINASI OVER CURRENT RELAY (OCR DAN GROUND FAULT RELAY (GFR PADA RECLOSER DI SALURAN PENYULANG PENEBEL

    Directory of Open Access Journals (Sweden)

    I Dewa Gde Agung Budhi Udiana

    2017-08-01

    Full Text Available Short circuit causing over current problem and can might causing interference of the equipment performance such as distribution transformers also causing widespread disruption occurred. In resolving such interference is required as protection system on the distribution system. Seeing all above is needed coordination between the supporting component of the protection system which is consisted of Over Current Relay (OCR and Ground Fault Relay (GFR. The research was conducted at PT. PLN (Persero South Bali Area Network, INDONESIA on recloser in the feeder line of Penebel. OCR setting between the Relay feeder of Penebel, Recloser Celagi, Recloser Bakisan, and Recloser Benana still less selective, with time value coordination between average security was still less than 0,2 second. Then OCR setting and GFR relay feeder of Penebel, Recloser Celagi, Recloser Bakisan, and Recloser Benana was recommended for re-setting in order to minimize disruption and electric power distribution system to be reliable.

  6. Performance analysis of two-way amplify and forward relaying with adaptive modulation

    KAUST Repository

    Hwang, Kyusung; Ko, Youngchai; Alouini, Mohamed-Slim

    2009-01-01

    the best relay selection scheme in this work. Based on the proposed selection criterion for the best relay, we analyze the average spectral efficiency by its approximated upper bound. In addition, we extend the proposed scheme to the case where a direct

  7. Selective memory generalization by spatial patterning of protein synthesis.

    Science.gov (United States)

    O'Donnell, Cian; Sejnowski, Terrence J

    2014-04-16

    Protein synthesis is crucial for both persistent synaptic plasticity and long-term memory. De novo protein expression can be restricted to specific neurons within a population, and to specific dendrites within a single neuron. Despite its ubiquity, the functional benefits of spatial protein regulation for learning are unknown. We used computational modeling to study this problem. We found that spatially patterned protein synthesis can enable selective consolidation of some memories but forgetting of others, even for simultaneous events that are represented by the same neural population. Key factors regulating selectivity include the functional clustering of synapses on dendrites, and the sparsity and overlap of neural activity patterns at the circuit level. Based on these findings, we proposed a two-step model for selective memory generalization during REM and slow-wave sleep. The pattern-matching framework we propose may be broadly applicable to spatial protein signaling throughout cortex and hippocampus. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Half-Duplex and Full-Duplex AF and DF Relaying with Energy-Harvesting in Log-Normal Fading

    KAUST Repository

    Rabie, Khaled M.

    2017-08-15

    Energy-harvesting (EH) and wireless power transfer in cooperative relaying networks have recently attracted a considerable amount of research attention. Most of the existing work on this topic however focuses on Rayleigh fading channels, which represent outdoor environments. In contrast, this paper is dedicated to analyze the performance of dual-hop relaying systems with EH over indoor channels characterized by log-normal fading. Both half-duplex (HD) and full-duplex (FD) relaying mechanisms are studied in this work with decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols. In addition, three EH schemes are investigated, namely, time switching relaying, power splitting relaying and ideal relaying receiver which serves as a lower bound. The system performance is evaluated in terms of the ergodic outage probability for which we derive accurate analytical expressions. Monte Carlo simulations are provided throughout to validate the accuracy of our analysis. Results reveal that, in both HD and FD scenarios, AF relaying performs only slightly worse than DF relaying which can make the former a more efficient solution when the processing energy cost at the DF relay is taken into account. It is also shown that FD relaying systems can generally outperform HD relaying schemes as long as the loop-back interference in FD is relatively small. Furthermore, increasing the variance of the log-normal channel has shown to deteriorate the performance in all the relaying and EH protocols considered.

  9. PERFORMANCE ANALYSIS OF COOPERATION SCHEMES IN EAVESDROPPER ASSISTED RELAY CHANNEL

    Directory of Open Access Journals (Sweden)

    Vaibhav Kumar Gupta

    2014-06-01

    Full Text Available The prominence of the wireless communication has been urging the monotonically increasing demand of security and privacy. In wireless systems, the notion of perfect secrecy of information with respect to illegitimate nodes can be ensured via physical layer security (PLS techniques. Unfortunately, they can be made less effective if source- eavesdropper wiretap channel is better than the main source-receiver channel. The various node cooperation schemes can be employed to combat this limitation where a relay node assists the communication to improve the performance significantly. In this paper, a four node wireless communication system consisting of a source, a destination, a relay and an eavesdropper as wire-tapper has been considered. The performance of the traditional cooperation schemes in terms of secrecy rate has been investigated with a different scenario where relay node helps the eavesdropper to deteriorate the secrecy rate. In addition, since legitimate receiver can overhear the transmission of relay, it favours the achievable secrecy rate. We formulate an analytical expression of conditional secrecy outage probability for the investigated system. From the obtained simulation results, it has been observed that secrecy rate is monotonically increases with path loss index. Furthermore, the proper selection of the system parameters leads to enhance the secrecy performance of the system even if relay pertains to degrade the performance. Amplify-and-forward, cooperation, decode-and-Forward, secrecy rate, relay.

  10. The 2009 Relay Race

    CERN Multimedia

    2009-01-01

    The 2009 CERN Relay Race was as popular as ever, with a record number of 88 teams competing. var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-0753-kbps-480x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-Multirate-200-to-753-kbps-480x360.wmv', 'false', 288, 216, 'https://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-posterframe-480x360-at-10-percent.jpg', '1178303', true, 'Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-0600-kbps-maxH-360-25-fps-audio-128-kbps-48-kHz-stereo.mp4'); Even the rain didn’t dampen the spirits, and it still managed to capture the ‘festival feeling’ with live music, beer and stalls from various CERN clubs set up outside Restaurant 1. The Powercuts on the podium after win...

  11. A time relay

    Energy Technology Data Exchange (ETDEWEB)

    Yosimura, K.; Sudzuki, Y.

    1981-06-18

    The synchronous micromotor of the time relay by means of a two staged cylindrical gear drive drives the gear wheel and the shaft of an actuating mechanism. The shaped drum of a cam mechanism, equipped with a vertical groove, which interacts in its upper part with a lever for driving the first commutating subassembly and in the lower, with a bent sector of a spring and plate movable contact of the second commutating subassembly, is attached to the lower end of the mechanism's shaft (V). The L-shaped lever of the second commutating subassembly's drive rests on a vertical rocking axle, located parallel to the shaft. Both pairs of spring and plate contacts are bracketed in two dielectric brackets which provide for a plane parallel disposition of the cited contacts. The operational time setting for the unit is a function of the initial angular position of the shaft, which is provided for by the attachment of a handle on its upper end.

  12. Screening test of relays used under pressurized sulfur hexafluoride (SF6)

    International Nuclear Information System (INIS)

    Kutsukake, Kenichi; Matsuda, Makoto; Hanashima, Susumu; Obara, Kenjiro

    2008-01-01

    Many measurement and control devices inside of a high voltage terminal of the JAEA-Tokai tandem accelerator are operated under pressurized sulfur hexafluoride gas (SF 6 ) of 0.5 MPa. This screening test has been carried out to select a relay, which is usable under the pressurized SF 6 for turn on and off a large current of the devices, from commercial relays used in the atmospheric condition. Four kinds of relays were tested: electromechanical relay (EMR), magnet contactor (MAG), solid-state relay (SSR) and hybrid relay (HYB). Temperature and appearance changes of the relay were collected as measurement items. In addition, a reason of contact trouble of the relays was considered from the results of qualitative elementary analysis and observation of the contact surface using the EDS (energy-dispersive X-ray spectroscopy) and the SEM (scanning electron microscope). As a result, the EMR and the MAG showed irregular contact in spite of input voltage and electric current had fed to an operational coil of the relay normally. It is caused by the sulfide or fluoride compounds, which were formed by chemical reaction between metals and sulfur or hydrogen fluoride due to dissociation of SF 6 in electric arcs. On the other hand, the performance of the SSR and the HYB is better than the EMR and the MAG, and it was found that these relays are available in the pressurized SF 6 of 0.5MPa in spite of the standard specification. (author)

  13. Working covariance model selection for generalized estimating equations.

    Science.gov (United States)

    Carey, Vincent J; Wang, You-Gan

    2011-11-20

    We investigate methods for data-based selection of working covariance models in the analysis of correlated data with generalized estimating equations. We study two selection criteria: Gaussian pseudolikelihood and a geodesic distance based on discrepancy between model-sensitive and model-robust regression parameter covariance estimators. The Gaussian pseudolikelihood is found in simulation to be reasonably sensitive for several response distributions and noncanonical mean-variance relations for longitudinal data. Application is also made to a clinical dataset. Assessment of adequacy of both correlation and variance models for longitudinal data should be routine in applications, and we describe open-source software supporting this practice. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Estimation and variable selection for generalized additive partial linear models

    KAUST Repository

    Wang, Li

    2011-08-01

    We study generalized additive partial linear models, proposing the use of polynomial spline smoothing for estimation of nonparametric functions, and deriving quasi-likelihood based estimators for the linear parameters. We establish asymptotic normality for the estimators of the parametric components. The procedure avoids solving large systems of equations as in kernel-based procedures and thus results in gains in computational simplicity. We further develop a class of variable selection procedures for the linear parameters by employing a nonconcave penalized quasi-likelihood, which is shown to have an asymptotic oracle property. Monte Carlo simulations and an empirical example are presented for illustration. © Institute of Mathematical Statistics, 2011.

  15. On the impact of information delay on location-based relaying: a markov modeling approach

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

    2012-01-01

    For centralized selection of communication relays, the necessary decision information needs to be collected from the mobile nodes by the access point (centralized decision point). In mobile scenarios, the required information collection and forwarding delays will affect the reliability of the col......For centralized selection of communication relays, the necessary decision information needs to be collected from the mobile nodes by the access point (centralized decision point). In mobile scenarios, the required information collection and forwarding delays will affect the reliability...... of the collected information and hence will influence the performance of the relay selection method. This paper analyzes this influence in the decision process for the example of a mobile location-based relay selection approach using a continuous time Markov chain model. The model is used to obtain optimal relay...

  16. Throughput maximization for buffer-aided hybrid half-/full-duplex relaying with self-interference

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-06-01

    In this work, we consider a two-hop cooperative setting where a source communicates with a destination through an intermediate relay node with a buffer. Unlike the existing body of work on buffer-aided half-duplex relaying, we consider a hybrid half-/full-duplex relaying scenario with loopback interference in the full-duplex mode. Depending on the channel outage and buffer states that are assumed available at the transmitters, the source and relay may either transmit simultaneously or revert to orthogonal transmission. Specifically, a joint source/relay scheduling and relaying mode selection mechanism is proposed to maximize the end-to-end throughput. The throughput maximization problem is converted to a linear program where the exact global optimal solution is efficiently obtained via standard convex/linear numerical optimization tools. Finally, the theoretical findings are corroborated with event-based simulations to provide the necessary performance validation.

  17. Accurate performance analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel

    2011-07-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may be considered unusable, and the destination may use a selection combining technique. We first derive the exact statistics of each hop, in terms of probability density function (PDF). Then, the PDFs are used to determine accurate closed form expressions for end-to-end outage probability for a transmission rate R. Furthermore, we evaluate the asymptotical performance analysis and the diversity order is deduced. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

  18. Model-based Evaluation of Location-based Relaying Policies in a Realistic Mobile Indoor Scenario

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

    2012-01-01

    For WLAN systems in which relaying is exploited for improving throughput performance, node mobility and in- formation collection delays can have a significant impact on the performance of a relay selection scheme. This paper analyzes this influence on the decision process using a previously...

  19. Generalized Selectivity Description for Polymeric Ion-Selective Electrodes Based on the Phase Boundary Potential Model.

    Science.gov (United States)

    Bakker, Eric

    2010-02-15

    A generalized description of the response behavior of potentiometric polymer membrane ion-selective electrodes is presented on the basis of ion-exchange equilibrium considerations at the sample-membrane interface. This paper includes and extends on previously reported theoretical advances in a more compact yet more comprehensive form. Specifically, the phase boundary potential model is used to derive the origin of the Nernstian response behavior in a single expression, which is valid for a membrane containing any charge type and complex stoichiometry of ionophore and ion-exchanger. This forms the basis for a generalized expression of the selectivity coefficient, which may be used for the selectivity optimization of ion-selective membranes containing electrically charged and neutral ionophores of any desired stoichiometry. It is shown to reduce to expressions published previously for specialized cases, and may be effectively applied to problems relevant in modern potentiometry. The treatment is extended to mixed ion solutions, offering a comprehensive yet formally compact derivation of the response behavior of ion-selective electrodes to a mixture of ions of any desired charge. It is compared to predictions by the less accurate Nicolsky-Eisenman equation. The influence of ion fluxes or any form of electrochemical excitation is not considered here, but may be readily incorporated if an ion-exchange equilibrium at the interface may be assumed in these cases.

  20. Generalized structural equations improve sexual-selection analyses.

    Directory of Open Access Journals (Sweden)

    Sonia Lombardi

    Full Text Available Sexual selection is an intense evolutionary force, which operates through competition for the access to breeding resources. There are many cases where male copulatory success is highly asymmetric, and few males are able to sire most females. Two main hypotheses were proposed to explain this asymmetry: "female choice" and "male dominance". The literature reports contrasting results. This variability may reflect actual differences among studied populations, but it may also be generated by methodological differences and statistical shortcomings in data analysis. A review of the statistical methods used so far in lek studies, shows a prevalence of Linear Models (LM and Generalized Linear Models (GLM which may be affected by problems in inferring cause-effect relationships; multi-collinearity among explanatory variables and erroneous handling of non-normal and non-continuous distributions of the response variable. In lek breeding, selective pressure is maximal, because large numbers of males and females congregate in small arenas. We used a dataset on lekking fallow deer (Dama dama, to contrast the methods and procedures employed so far, and we propose a novel approach based on Generalized Structural Equations Models (GSEMs. GSEMs combine the power and flexibility of both SEM and GLM in a unified modeling framework. We showed that LMs fail to identify several important predictors of male copulatory success and yields very imprecise parameter estimates. Minor variations in data transformation yield wide changes in results and the method appears unreliable. GLMs improved the analysis, but GSEMs provided better results, because the use of latent variables decreases the impact of measurement errors. Using GSEMs, we were able to test contrasting hypotheses and calculate both direct and indirect effects, and we reached a high precision of the estimates, which implies a high predictive ability. In synthesis, we recommend the use of GSEMs in studies on

  1. Performance limitations of relay neurons.

    Directory of Open Access Journals (Sweden)

    Rahul Agarwal

    Full Text Available Relay cells are prevalent throughout sensory systems and receive two types of inputs: driving and modulating. The driving input contains receptive field properties that must be transmitted while the modulating input alters the specifics of transmission. For example, the visual thalamus contains relay neurons that receive driving inputs from the retina that encode a visual image, and modulating inputs from reticular activating system and layer 6 of visual cortex that control what aspects of the image will be relayed back to visual cortex for perception. What gets relayed depends on several factors such as attentional demands and a subject's goals. In this paper, we analyze a biophysical based model of a relay cell and use systems theoretic tools to construct analytic bounds on how well the cell transmits a driving input as a function of the neuron's electrophysiological properties, the modulating input, and the driving signal parameters. We assume that the modulating input belongs to a class of sinusoidal signals and that the driving input is an irregular train of pulses with inter-pulse intervals obeying an exponential distribution. Our analysis applies to any [Formula: see text] order model as long as the neuron does not spike without a driving input pulse and exhibits a refractory period. Our bounds on relay reliability contain performance obtained through simulation of a second and third order model, and suggest, for instance, that if the frequency of the modulating input increases or the DC offset decreases, then relay increases. Our analysis also shows, for the first time, how the biophysical properties of the neuron (e.g. ion channel dynamics define the oscillatory patterns needed in the modulating input for appropriately timed relay of sensory information. In our discussion, we describe how our bounds predict experimentally observed neural activity in the basal ganglia in (i health, (ii in Parkinson's disease (PD, and (iii in PD during

  2. Speech-to-Speech Relay Service

    Science.gov (United States)

    Consumer Guide Speech to Speech Relay Service Speech-to-Speech (STS) is one form of Telecommunications Relay Service (TRS). TRS is a service that allows persons with hearing and speech disabilities ...

  3. Relay self interference minimisation using tapped filter

    KAUST Repository

    Jazzar, Saleh; Al-Naffouri, Tareq Y.

    2013-01-01

    In this paper we introduce a self interference (SI) estimation and minimisation technique for amplify and forward relays. Relays are used to help forward signals between a transmitter and a receiver. This helps increase the signal coverage

  4. Handover Framework for Relay Enhanced LTE Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Van Phan, Vinh; Raaf, Bernhard

    2009-01-01

    Relaying is one of the proposed technologies for future releases of UTRAN Long Term Evolution (LTE) networks. Introducing relaying is expected to increase the coverage and capacity of LTE networks. In order to enable relaying, the architecture, protocol and radio resource management procedures...... of LTE, such as handover, have to be modified. A user can be handed over not only between two base stations, but also between relays and base stations, and between two relays. With the introduction of relaying, there is a need for a new procedure to hand over a relay and all its associated users...... to another base station, allowing a flexible and dynamic relay deployment. In this paper, we extend the LTE release 8 handover mechanisms so that it can accommodate these new handover functionalities in a flexible manner....

  5. Securing Relay Networks with Artificial Noise: An Error Performance-Based Approach

    Directory of Open Access Journals (Sweden)

    Ying Liu

    2017-07-01

    Full Text Available We apply the concept of artificial and controlled interference in a two-hop relay network with an untrusted relay, aiming at enhancing the wireless communication secrecy between the source and the destination node. In order to shield the square quadrature amplitude-modulated (QAM signals transmitted from the source node to the relay, the destination node designs and transmits artificial noise (AN symbols to jam the relay reception. The objective of our considered AN design is to degrade the error probability performance at the untrusted relay, for different types of channel state information (CSI at the destination. By considering perfect knowledge of the instantaneous CSI of the source-to-relay and relay-to-destination links, we first present an analytical expression for the symbol error rate (SER performance at the relay. Based on the assumption of an average power constraint at the destination node, we then derive the optimal phase and power distribution of the AN that maximizes the SER at the relay. Furthermore, we obtain the optimal AN design for the case where only statistical CSI is available at the destination node. For both cases, our study reveals that the Gaussian distribution is generally not optimal to generate AN symbols. The presented AN design takes into account practical parameters for the communication links, such as QAM signaling and maximum likelihood decoding.

  6. 76 FR 24442 - Structure and Practices of the Video Relay Service Program; Telecommunications Relay Services and...

    Science.gov (United States)

    2011-05-02

    ... same meaning as the terms ``small business,'' ``small organization,'' and ``small governmental...] Structure and Practices of the Video Relay Service Program; Telecommunications Relay Services and Speech-to... Commission's Structure and Practices of the Video Relay Service Program; Telecommunications Relay Services...

  7. Performance analysis of two-way amplify and forward relaying with adaptive modulation

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

    In this paper, we study two-way amplify-and-forward relaying in conjunction with adaptive modulation over a multiple relay network. In order to keep the diversity order equal to the number of relays and maintain a low complexity, we consider the best relay selection scheme in this work. Based on the proposed selection criterion for the best relay, we analyze the average spectral efficiency by its approximated upper bound. In addition, we extend the proposed scheme to the case where a direct path between source and destination exists. Our numerical examples show that the proposed system offers a considerable gain in the spectral efficiency while satisfying the error rates requirements. ©2009 IEEE.

  8. Quantum cryptography with an ideal local relay

    DEFF Research Database (Denmark)

    Spedalieri, Gaetana; Ottaviani, Carlo; Braunstein, Samuel L.

    2015-01-01

    We consider two remote parties connected to a relay by two quantum channels. To generate a secret key, they transmit coherent states to the relay, where the states are subject to a continuous-variable (CV) Bell detection. We study the ideal case where Alice's channel is lossless, i.e., the relay ...

  9. Robust distributed cognitive relay beamforming

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2012-05-01

    In this paper, we present a distributed relay beamformer design for a cognitive radio network in which a cognitive (or secondary) transmit node communicates with a secondary receive node assisted by a set of cognitive non-regenerative relays. The secondary nodes share the spectrum with a licensed primary user (PU) node, and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. The proposed robust cognitive relay beamformer design seeks to minimize the total relay transmit power while ensuring that the transceiver signal-to-interference- plus-noise ratio and PU interference constraints are satisfied. The proposed design takes into account a parameter of the error in the channel state information (CSI) to render the performance of the beamformer robust in the presence of imperfect CSI. Though the original problem is non-convex, we show that the proposed design can be reformulated as a tractable convex optimization problem that can be solved efficiently. Numerical results are provided and illustrate the performance of the proposed designs for different network operating conditions and parameters. © 2012 IEEE.

  10. Colorimetric and fluorescent chemosensor for highly selective and sensitive relay detection of Cu2 + and H2PO4- in aqueous media

    Science.gov (United States)

    Su, Jun-Xia; Wang, Xiao-Ting; Chang, Jing; Wu, Gui-Yuan; Wang, Hai-Ming; Yao, Hong; Lin, Qi; Zhang, You-Ming; Wei, Tai-Bao

    2017-07-01

    In this manuscript, a new colorimetric and fluorescent chemosensor (T) was designed and synthesized, it could successively detect Cu2 + and H2PO4- in DMSO/H2O (v/v = 9:1, pH = 7.2) buffer solution with high selectivity and sensitivity. When added Cu2 + ions into the solution of T, it showed a color changes from yellow to colorless, meanwhile, the green fluorescence of sensor T quenched. This recognition behavior was not affected in the presence of other cations, including Hg2 +, Ag+, Ca2 +, Co2 +, Ni2 +, Cd2 +, Pb2 +, Zn2 +, Cr3 +, and Mg2 + ions. More interestingly, the Cu2 + ions contain sensor T solution could recover the color and fluorescence upon the addition of H2PO4- anions in the same medium. And other surveyed anions (including F-, Cl-, Br-, I-, AcO-, HSO4-, ClO4-, CN- and SCN-) had nearly no influence on the recognition behavior. The detection limits of T to Cu2 + and T-Cu2 + to H2PO4- were evaluated to be 1.609 × 10- 8 M and 0.994 × 10- 7 M, respectively. In addition, the sensor T also could be served as a recyclable component and the logic gate output was also defined in sensing materials. The test strips based on sensor T were fabricated, which acted as a convenient and efficient Cu2 + and H2PO4- test kits.

  11. CHAIN-WISE GENERALIZATION OF ROAD NETWORKS USING MODEL SELECTION

    Directory of Open Access Journals (Sweden)

    D. Bulatov

    2017-05-01

    Full Text Available Streets are essential entities of urban terrain and their automatized extraction from airborne sensor data is cumbersome because of a complex interplay of geometric, topological and semantic aspects. Given a binary image, representing the road class, centerlines of road segments are extracted by means of skeletonization. The focus of this paper lies in a well-reasoned representation of these segments by means of geometric primitives, such as straight line segments as well as circle and ellipse arcs. We propose the fusion of raw segments based on similarity criteria; the output of this process are the so-called chains which better match to the intuitive perception of what a street is. Further, we propose a two-step approach for chain-wise generalization. First, the chain is pre-segmented using circlePeucker and finally, model selection is used to decide whether two neighboring segments should be fused to a new geometric entity. Thereby, we consider both variance-covariance analysis of residuals and model complexity. The results on a complex data-set with many traffic roundabouts indicate the benefits of the proposed procedure.

  12. Spoiled Onions: Exposing Malicious Tor Exit Relays

    OpenAIRE

    Winter, Philipp; Lindskog, Stefan

    2014-01-01

    Several hundred Tor exit relays together push more than 1 GiB/s of network traffic. However, it is easy for exit relays to snoop and tamper with anonymised network traffic and as all relays are run by independent volunteers, not all of them are innocuous. In this paper, we seek to expose malicious exit relays and document their actions. First, we monitored the Tor network after developing a fast and modular exit relay scanner. We implemented several scanning modules for detecting common attac...

  13. IE Information Notice No. 85-82: Diesel generator differential protection relay not seismically qualified

    International Nuclear Information System (INIS)

    Jordan, E.L.

    1992-01-01

    Licensees of BWR and PWR nuclear generating stations have reported using a high-speed differential protection relay that has been declared by the manufacturer to be not seismically qualified for the service intended. The relay, GE Model 12CFD, which is being used for emergency diesel generator protection against electrical shorts and grounds at the generator output, has not been seismically qualified to operate in the de-energized state for this application. Generally, the relay operates in the de-energized position before EDG operation. However, it then operates in the energized position whenever the EDG provides an electrical output to essential Class IE components. The safety concern of this issue involves an inadvertent activation of the normally de-energized relay from a seismic event. Momentary activation of the relay, in the circuits examined, blocks the automatic start feature of the EDG during certain emergency plant conditions through operation of another relay in the system. The NRC review of the problems concluded that the relays should be seismically qualified in their energized and de-energized states to preclude their spurious activation during a seismic event. Additionally, review of GE's GER 3069 report, ''Relay Protection of Class IE Systems,'' shows that the 12CFD differential relays were successfully tested for 3.5 g in the energized modes and only 0.75 g in the de-energized mode. Review of GE's GER 3069 report also revealed that GE type IJD differential relays do meet seismic requirements in all modes of operation mentioned above and is the GE recommendation for replacement of the differential relay in question

  14. An Optimal Analysis in Wireless Powered Full-duplex Relaying Network

    Directory of Open Access Journals (Sweden)

    K.-T. Nguyen

    2017-04-01

    Full Text Available Wireless-powered cellular networks (WPCNs are currently being investigated to exploit the reliability and improve battery lifetime of mobile users. This paper investigates the energy harvesting structure of the full-duplex relaying networks. By using the time switching based relaying (TSR protocol and Amplify-and-Forward (AF model in delay-limited transmission scheme, we propose the closed-form expression of the outage probability and then calculate the optimal throughput. An important result can be taken obviously that the time fraction in TSR, the position of relay, the noise as well as the energy conversation impacting on the outage probability as well as the optimal throughput. By Monte Carlo simulation, the numerical results indicate an effective relaying strategy in full-duplex cooperative systems. Finally, we provide fundamental design guidelines for selecting time fraction in TSR that satisfies the requirements of a practical relaying system.

  15. Alternate transmission with half-duplex relaying in MIMO interference relay networks

    KAUST Repository

    Park, Seongho

    2013-12-01

    In this paper, we consider an alternate transmission scheme for a multiple-input multiple-output interference relay channel where multiple sources transmit their own signals to their corresponding destinations via one of two relaying groups alternately every time phase. Each of the relaying groups has arbitrary number of relays, and each relay operates in half-duplex amplify-and-forward mode. In our scheme, the received signals at the relay nodes consist of desired signals and two different interference signals such as the inter-source interferences and the inter-group interferences which are caused by the phase incoherence of relaying. As such, we propose an iterative interference alignment algorithm to mitigate the interferences. We show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying system in the interference relay channels. © 2013 IEEE.

  16. The CERN Relay Race: A Runaway Success!

    CERN Multimedia

    Staff Association

    2018-01-01

    24th May saw the traditional Relay Race take place at CERN, organised jointly by the Running Club and the CERN Staff Association. In 2018, the Relay Race lived up to expectations with a record number of participants, with no fewer than 848 entries across different categories! In total 135 teams of 6 runners and 38 walkers completed the course on the Meyrin site in beautiful sunshine. Congratulations to all those who took part! Ghislain Roy, President of the Staff Association, fired the starting pistol for the first batch of runners, which included a team from the Directorate, with the Director General also taking part. Demonstrating interest in this event at the highest level of the Organization. Thank you for this much-appreciated commitment! Also a number of very high-level runners brought added excitement to the 2018 edition. The 1000-meter men’s race was won by Marcin Patecki from the CERN Running Club in 2’40, just in front of Baptiste Fieux from the Berthie Sport team who came in at...

  17. Enhancing overcurrent relay performance using wavelet packet transform

    International Nuclear Information System (INIS)

    Adly, A.R.

    2012-01-01

    The function of a power system relaying is to cause the prompt removal of any element of power system from service when it is subjected to short circuit or it starts to operate in any abnormal manner that might cause damage or otherwise interfere with the effective operation of the rest of the system. Overcurrent protection is one of the most widely used relays in power system which is used for both primary and back-up protective relays, and applied in every protective zone in the system. The application of time overcurrent relays in power system presents serious limitations in terms of sensitivity and selectivity. Digital forms of such relays are being mostly used which have the advantages of data recording and adaptive features. This thesis introduces a technique based on Wavelet Packet Transform (WPT) to detect short circuit faults within wide variation in generating conditions, with very small voltage variation, and High-Impedance Faults (HIFs). Besides, it examines the load current continuously and changes the relay pick up value adaptively. WPT is used to estimate proper value for the RMS fundamental and hence calculate trip time accurately even that when the signals have been contaminated with other harmonics, inter harmonics or subharmonic. Simulation work was conducted using Alternative Transient Program (ATP) package. A radial distribution system and series compensated line are modeled as case studies. The performance of the proposed overcurrent scheme for both lines is extensively tested during different operating conditions including; normal, internal short circuit faults, HIFs and similar situations to HIFs: such as capacitor switching (in), capacitor switching (out), load switching, and no load line switching. This thesis also uses a technique that estimates the location of short circuit faults on a radial distribution system. The technique was tested to evaluate its suitability. The results indicate that the proposed technique works well. It also

  18. Switched diversity strategies for dual-hop amplify-and-forward relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine; Radaydeh, Redha Mahmoud Mesleh; Alouini, Mohamed-Slim

    2012-01-01

    This study investigates different receive single-branch switch-based diversity schemes for dual-hop amplify-and-forward relaying networks. Specifically, three receive processing algorithms are adopted, in which the receive branch is selected using

  19. Detect-and-forward in two-hop relay channels: a metrics-based analysis

    KAUST Repository

    Benjillali, Mustapha

    2010-06-01

    In this paper, we analyze the coded performance of a cooperative system with multiple parallel relays using "Detect-and-Forward" (DetF) strategy where each relay demodulates the overheard signal and forwards the detected binary words. The proposed method is based on the probabilistic characterization of the reliability metrics given under the form of L-values. First, we derive analytical expressions of the probability density functions (PDFs) of the L-values in the elementary two-hop DetF relay channel with different source-relay channel state information assumptions. Then, we apply the obtained expressions to calculate the theoretically achievable rates and compare them with the practical throughput of a simulated turbo-coded transmission. Next, we derive tight approximations for the end-to-end coded bit error rate (BER) of a general cooperative scheme with multiple parallel relays. Simulation results demonstrate the accuracy of our derivations for different cooperation configurations and conditions. © 2010 IEEE.

  20. Energy efficient circuit design using nanoelectromechanical relays

    Science.gov (United States)

    Venkatasubramanian, Ramakrishnan

    Nano-electromechanical (NEM) relays are a promising class of emerging devices that offer zero off-state leakage and behave like an ideal switch. Recent advances in planar fabrication technology have demonstrated that microelectromechanical (MEMS) scale miniature relays could be manufactured reliably and could be used to build fully functional, complex integrated circuits. The zero leakage operation of relays has renewed the interest in relay based low power logic design. This dissertation explores circuit architectures using NEM relays and NEMS-CMOS heterogeneous integration. Novel circuit topologies for sequential logic, memory, and power management circuits have been proposed taking into consideration the NEM relay device properties and optimizing for energy efficiency and area. In nanoscale electromechanical devices, dispersion forces like Van der Waals' force (vdW) affect the pull-in stability of the relay devices significantly. Verilog-A electromechanical model of the suspended gate relay operating at 1V with a nominal air gap of 5 - 10nm has been developed taking into account all the electrical, mechanical and dispersion effects. This dissertation explores different relay based latch and flip-flop topologies. It has been shown that as few as 4 relay cells could be used to build flip-flops. An integrated voltage doubler based flip flop that improves the performance by 2X by overdriving Vgb has been proposed. Three NEM relay based parallel readout memory bitcell architectures have been proposed that have faster access time, and remove the reliability issues associated with previously reported serial readout architectures. A paradigm shift in design of power switches using NEM relays is proposed. An interesting property of the relay device is that the ON state resistance (Ron) of the NEM relay switch is constant and is insensitive to the gate slew rate. This coupled with infinite OFF state resistance (Roff ) offers significant area and power advantages over CMOS

  1. IEEE C37.98-1987: IEEE standard seismic testing of relays

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This standard specifies the procedures to be used in the seismic testing of relays used in power system facilities. The standard is concerned with the determination of the seismic fragility level of relays and also gives recommendations for proof testing. The purpose of this standard is to establish procedures for determining the seismic capabilities of protective and auxiliary relays. These procedures employ what has been called fragility testing in IEEE Std 344-1987. To define the conditions for fragility testing of relays, parameters in three separate areas must be specified. In general, they are (1) the electrical settings and inputs to the relay, and other information to define its conditions during the test; (2) the change in state, deviation in operating characteristics or tolerances, or other change of performance of the relay that constitutes failure; (3) the seismic vibration environment to be imposed during the test. Since it is not possible to define the conditions for every conceivable application for all relays, those parameters, which in practice encompass the majority of applications, have been specified in this standard. When the application of the relay is other than as specified under any of (1), (2), and (3), or if it is not practical to apply existing results of fragility tests to that new application, then proof testing must be performed for that new case

  2. IEEE C37.98-1978: IEEE standard seismic testing of relays

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This standard specifies the procedures to be used in the seismic testing of relays used in power system facilities. The standard is concerned with the determination of the seismic fragility level of relays and also gives recommendations for proof testing. The purpose of this standard is to establish procedures for determining the seismic capabilities of protective and auxiliary relays. These procedures employ what has been called fragility testing in ANSI/IEEE Std 344-1975, Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations. In order to define the conditions for fragility testing of relays, parameters in three separate areas must be specified. In general they are: (1) the electrical settings and inputs to the relay, and other information to define its conditions during the test; (2) the change in state, deviation in operating characteristics or tolerances, or other change of performance of the relay which constitutes failure; (3) the seismic vibration environment to be imposed during the test. Since it is not possible to define the conditions for every conceivable application for all relays, those parameters, which in practice encompass the majority of applications, have been specified in this standard. When the application of the relay is other than as specified under any of (1), (2), and (3), or if it is not practical to apply existing results of fragility tests to that new case

  3. Considering Pilot Protection in the Optimal Coordination of Distance and Directional Overcurrent Relays

    Directory of Open Access Journals (Sweden)

    Y. Damchi

    2015-06-01

    Full Text Available The aim of the relay coordination is that protection systems detect and isolate the faulted part as fast and selective as possible. On the other hand, in order to reduce the fault clearing time, distance protection relays are usually equipped with pilot protection schemes. Such schemes can be considered in the distance and directional overcurrent relays (D&DOCRs coordination to achieve faster protection systems, while the selectivity is maintained. Therefore, in this paper, a new formulation is presented for the relay coordination problem considering pilot protection. In the proposed formulation, the selectivity constraints for the primary distance and backup overcurrent relays are defined based on the fault at the end of the transmission lines, rather than those at the end of the first zone of the primary distance relay. To solve this nonlinear optimization problem, a combination of genetic algorithm (GA and linear programming (LP is used as a hybrid genetic algorithm (HGA. The proposed approach is tested on an 8-bus and the IEEE 14-bus test systems. Simulation results indicate that considering the pilot protection in the D&DOCRS coordination, not only obtains feasible and effective solutions for the relay settings, but also reduces the overall operating time of the protection system.

  4. Performance Analysis of Amplify-and-Forward Two-Way Relaying with Co-Channel Interference and Channel Estimation Error

    KAUST Repository

    Liang Yang,

    2013-06-01

    In this paper, we consider the performance of a two-way amplify-and-forward relaying network (AF TWRN) in the presence of unequal power co-channel interferers (CCI). Specifically, we first consider AF TWRN with an interference-limited relay and two noisy-nodes with channel estimation errors and CCI. We derive the approximate signal-to-interference plus noise ratio expressions and then use them to evaluate the outage probability, error probability, and achievable rate. Subsequently, to investigate the joint effects of the channel estimation error and CCI on the system performance, we extend our analysis to a multiple-relay network and derive several asymptotic performance expressions. For comparison purposes, we also provide the analysis for the relay selection scheme under the total power constraint at the relays. For AF TWRN with channel estimation error and CCI, numerical results show that the performance of the relay selection scheme is not always better than that of the all-relay participating case. In particular, the relay selection scheme can improve the system performance in the case of high power levels at the sources and small powers at the relays.

  5. Meaning identification and meaning selection for general language monolingual dictionaries

    DEFF Research Database (Denmark)

    Bergenholtz, Henning; Agerbo, Heidi

    2014-01-01

    The traditional way for lexicographers to deal with polysemy in dictionaries is by applying the terms lumping and splitting. We will not follow this tradition. Instead, we argue that the identification and selection of meaning items (= polysems) should be treated in the same way as the identifica......The traditional way for lexicographers to deal with polysemy in dictionaries is by applying the terms lumping and splitting. We will not follow this tradition. Instead, we argue that the identification and selection of meaning items (= polysems) should be treated in the same way...... to references in the world (in this contribution called things), followed by a formulation of the identified meaning items which can be used for reception situations. Not always – as in the case of lemma selection – will all the identified meaning items be included in the dictionary. The selection of identified...... meaning items will depend on the genuine purpose of the dictionary....

  6. 13 CFR 108.340 - Evaluation and selection-general.

    Science.gov (United States)

    2010-01-01

    ... VENTURE CAPITAL (âNMVCâ) PROGRAM Evaluation and Selection of NMVC Companies § 108.340 Evaluation and... Applicants in such a way as to promote Developmental Venture Capital investments nationwide and in both urban...

  7. 12 CFR 1805.700 - Evaluation and selection-general.

    Science.gov (United States)

    2010-01-01

    ... Section 1805.700 Banks and Banking COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS FUND, DEPARTMENT OF THE TREASURY COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS PROGRAM Evaluation and Selection of Applications... Applicants that vary by institution type, total asset size, stage of organizational development, markets...

  8. Energy-efficient cooperative protocols for full-duplex relay channels

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-12-01

    In this work, energy-efficient cooperative protocols are studied for full-duplex relaying (FDR) with loopback interference. In these protocols, relay assistance is only sought under certain conditions on the different link outages to ensure effective cooperation. Recently, an energy-efficient selective decode-And-forward protocol was proposed for FDR, and was shown to outperform existing schemes in terms of outage. Here, we propose an incremental selective decode-And-forward protocol that offers additional power savings, while keeping the same outage performance. We compare the performance of the two protocols in terms of the end-to-end signal-to-noise ratio cumulative distribution function via closed-form expressions. Finally, we corroborate our theoretical results with simulation, and show the relative relay power savings in comparison to non-selective cooperation in which the relay cooperates regardless of channel conditions. © 2013 IEEE.

  9. Energy-efficient cooperative protocols for full-duplex relay channels

    KAUST Repository

    Khafagy, Mohammad Galal; Ismail, Amr; Alouini, Mohamed-Slim; Aï ssa, Sonia

    2013-01-01

    In this work, energy-efficient cooperative protocols are studied for full-duplex relaying (FDR) with loopback interference. In these protocols, relay assistance is only sought under certain conditions on the different link outages to ensure effective cooperation. Recently, an energy-efficient selective decode-And-forward protocol was proposed for FDR, and was shown to outperform existing schemes in terms of outage. Here, we propose an incremental selective decode-And-forward protocol that offers additional power savings, while keeping the same outage performance. We compare the performance of the two protocols in terms of the end-to-end signal-to-noise ratio cumulative distribution function via closed-form expressions. Finally, we corroborate our theoretical results with simulation, and show the relative relay power savings in comparison to non-selective cooperation in which the relay cooperates regardless of channel conditions. © 2013 IEEE.

  10. Relay Precoder Optimization in MIMO-Relay Networks With Imperfect CSI

    KAUST Repository

    Pandarakkottilil, Ubaidulla; Chockalingam, A.

    2011-01-01

    In this paper, we consider robust joint designs of relay precoder and destination receive filters in a nonregenerative multiple-input multiple-output (MIMO) relay network. The network consists of multiple source-destination node pairs assisted by a

  11. Alternate transmission with half-duplex relaying in MIMO interference relay networks

    KAUST Repository

    Park, Seongho; Ko, Youngchai; Park, Kihong; Alouini, Mohamed-Slim

    2013-01-01

    In this paper, we consider an alternate transmission scheme for a multiple-input multiple-output interference relay channel where multiple sources transmit their own signals to their corresponding destinations via one of two relaying groups

  12. Alternate transmission relaying based on interference alignment in 3-relay half-duplex MIMO systems

    KAUST Repository

    Park, Seongho; Park, Kihong; Ko, Youngchai; Alouini, Mohamed-Slim

    2012-01-01

    In a half-duplex relaying, the capacity pre-log factor 1/2 is a major drawback in spectral efficiency. This paper proposes a linear precoding/decoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can suppress the inter-relay interference resulting from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying. © 2012 IEEE.

  13. SWIPT in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma; Salem, Ahmed Sultan; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, we consider a multiuser multiple- input multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting relays and multiple destinations. Since the end-to-end sum rate

  14. Alternate transmission relaying based on interference alignment in 3-relay half-duplex MIMO systems

    KAUST Repository

    Park, Seongho

    2012-09-01

    In a half-duplex relaying, the capacity pre-log factor 1/2 is a major drawback in spectral efficiency. This paper proposes a linear precoding/decoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can suppress the inter-relay interference resulting from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying. © 2012 IEEE.

  15. Novel Material Integration for Reliable and Energy-Efficient NEM Relay Technology

    Science.gov (United States)

    Chen, I.-Ru

    Energy-efficient switching devices have become ever more important with the emergence of ubiquitous computing. NEM relays are promising to complement CMOS transistors as circuit building blocks for future ultra-low-power information processing, and as such have recently attracted significant attention from the semiconductor industry and researchers. Relay technology potentially can overcome the energy efficiency limit for conventional CMOS technology due to several key characteristics, including zero OFF-state leakage, abrupt switching behavior, and potentially very low active energy consumption. However, two key issues must be addressed for relay technology to reach its full potential: surface oxide formation at the contacting surfaces leading to increased ON-state resistance after switching, and high switching voltages due to strain gradient present within the relay structure. This dissertation advances NEM relay technology by investigating solutions to both of these pressing issues. Ruthenium, whose native oxide is conductive, is proposed as the contacting material to improve relay ON-state resistance stability. Ruthenium-contact relays are fabricated after overcoming several process integration challenges, and show superior ON-state resistance stability in electrical measurements and extended device lifetime. The relay structural film is optimized via stress matching among all layers within the structure, to provide lower strain gradient (below 10E-3/microm -1) and hence lower switching voltage. These advancements in relay technology, along with the integration of a metallic interconnect layer, enable complex relay-based circuit demonstration. In addition to the experimental efforts, this dissertation theoretically analyzes the energy efficiency limit of a NEM switch, which is generally believed to be limited by the surface adhesion energy. New compact (electronic device technology.

  16. Optimal portfolio selection for general provisioning and terminal wealth problems

    NARCIS (Netherlands)

    van Weert, K.; Dhaene, J.; Goovaerts, M.

    2010-01-01

    In Dhaene et al. (2005), multiperiod portfolio selection problems are discussed, using an analytical approach to find optimal constant mix investment strategies in a provisioning or a savings context. In this paper we extend some of these results, investigating some specific, real-life situations.

  17. Optimal portfolio selection for general provisioning and terminal wealth problems

    NARCIS (Netherlands)

    van Weert, K.; Dhaene, J.; Goovaerts, M.

    2009-01-01

    In Dhaene et al. (2005), multiperiod portfolio selection problems are discussed, using an analytical approach to find optimal constant mix investment strategies in a provisioning or savings context. In this paper we extend some of these results, investigating some specific, real-life situations. The

  18. Relay self interference minimisation using tapped filter

    KAUST Repository

    Jazzar, Saleh

    2013-05-01

    In this paper we introduce a self interference (SI) estimation and minimisation technique for amplify and forward relays. Relays are used to help forward signals between a transmitter and a receiver. This helps increase the signal coverage and reduce the required transmitted signal power. One problem that faces relays communications is the leaked signal from the relay\\'s output to its input. This will cause an SI problem where the new received signal at the relay\\'s input will be added with the unwanted leaked signal from the relay\\'s output. A Solution is proposed in this paper to estimate and minimise this SI which is based upon using a tapped filter at the destination. To get the optimum weights for this tapped filter, some channel parameters must be estimated first. This is performed blindly at the destination without the need of any training. This channel parameter estimation method is named the blind-self-interference-channel-estimation (BSICE) method. The next step in the proposed solution is to estimate the tapped filter\\'s weights. This is performed by minimising the mean squared error (MSE) at the destination. This proposed method is named the MSE-Optimum Weight (MSE-OW) method. Simulation results are provided in this paper to verify the performance of BSICE and MSE-OW methods. © 2013 IEEE.

  19. Analysis of errors of radiation relay, (1)

    International Nuclear Information System (INIS)

    Koyanagi, Takami; Nakajima, Sinichi

    1976-01-01

    The statistical error of liquid level controlled by radiation relay is analysed and a method of minimizing the error is proposed. This method comes to the problem of optimum setting of the time constant of radiation relay. The equations for obtaining the value of time constant are presented and the numerical results are shown in a table and plotted in a figure. The optimum time constant of the upper level control relay is entirely different from that of the lower level control relay. (auth.)

  20. Experimental evaluation of earthquake induced relay chattering

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Hofmayer, C.; Shteyngart, S.

    1990-01-01

    An experimental evaluation of relay performance under vibratory environments is discussed in this paper. Single frequency excitation was used for most tests. Limited tests were performed with random multifrequency inputs. The capacity of each relay was established based on a two-millisecond chatter criterion. The experimental techniques are described and the effects of parameters in controlling the relay capacity levels are illustrated with test data. A wide variation of the capacity levels was observed due to the influence of parameters related to the design of the relay and nature of the input motion. 3 refs., 15 figs

  1. On the performance of spectrum sharing systems with two-way relaying and multiuser diversity

    KAUST Repository

    Yang, Liang

    2012-08-01

    In this letter, we consider a spectrum sharing network with two-way relaying and multi-user diversity. More specifically, one secondary transmitter with the best channel quality is selected and splits its partial power to relay its received signals to the primary users by using the amplify-and-forward relaying protocol. We derive a tight approximation for the resulting outage probability. Based on this formula, the performance of the spectral sharing region and the cell coverage are analyzed. Numerical results are given to verify our analysis and are discussed to illustrate the advantages of our newly proposed scheme. © 1997-2012 IEEE.

  2. 78 FR 40407 - Structure and Practices of the Video Relay Service Program: Telecommunications Relay Services and...

    Science.gov (United States)

    2013-07-05

    ...] Structure and Practices of the Video Relay Service Program: Telecommunications Relay Services and Speech-to... telecommunications relay services (TRS) program continues to offer functional equivalence to all eligible users and..., identified by CG Docket Nos. 10-51 and 03-123, by any of the following methods: Electronic Filers: Comments...

  3. General Music Teachers' Backgrounds and Multicultural Repertoire Selection

    Science.gov (United States)

    Lee, Soojin

    2018-01-01

    The purpose of this qualitative study was to examine how teachers' backgrounds could contribute to their decisions to include music from diverse cultures. Analysis of interviews with three general music teachers indicated that their music training and experiences, ethnic backgrounds, and years of teaching experience may have influenced their…

  4. [Diagnosis and treatment in general internal medicine. Curriculum selection].

    Science.gov (United States)

    Casal, E R; Vázquez, E N; Husni, C

    1994-01-01

    In our country general internists are the providers of adult medical care in urban areas. In the past twenty years, with the increasing subspecialization within internal medicine and the development of advances in technology, the role of the general internist seems to be endangered. Recently much attention has been focused on this area and Divisions and Programs of General Internal Medicine have been established in most medical schools in the USA. The University of Buenos Aires instituted a Program of General Internal Medicine in its major teaching hospital in 1987. One of its purposes was to offer an educational experience to residents in the field of internal medicine primary care. This paper summarizes how this program was carried out and the subjects proposed in the area of Diagnosis and Treatment. The Program of General Internal Medicine is performed in the Outpatient Division and it is staffed by 3 faculty members and 4 fellows. Residents in Internal Medicine have a three month, full-time block rotation in the Program. A young, city dwelling, lower middle class population participates in the Program, with almost 10000 visits a year. The Program offers an experience that includes supervised patient care, an average of 100 office visits a month, and seminars and/or workshops covering topics of "Diagnosis and Treatment", "Case Presentations", "Clinical Epidemiology", "Prevention", and "Doctor-Patient Interview". In the area of Diagnosis and Treatment, the criteria used were: 1-frequency of diagnosis as determined by previous investigations, 2-relevant clinical conditions absent from the frequency list as determined by a consensus process by faculty members.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Protective relaying theory and applications

    CERN Document Server

    Elmore, Walter A

    2003-01-01

    Targeting the latest microprocessor technologies for more sophisticated applications in the field of power system short circuit detection, this revised and updated source imparts fundamental concepts and breakthrough science for the isolation of faulty equipment and minimization of damage in power system apparatus. The Second Edition clearly describes key procedures, devices, and elements crucial to the protection and control of power system function and stability. It includes chapters and expertise from the most knowledgeable experts in the field of protective relaying, and describes micropro

  6. Diversity-Multiplexing Trade-off for Coordinated Direct and Relay Schemes

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; De Carvalho, Elisabeth

    2013-01-01

    The recent years have brought a significant body of research on wireless Two-Way Relaying (TWR), where the use of network coding brings an evident advantage in terms of data rates. Yet, TWR scenarios represent only a special case and it is of interest to devise similar techniques in more general...... Direct/Relay (CDR) schemes, which involve two flows, of a direct and a relayed user. In this paper we characterize a CDR scheme by deriving/bounding the Diversity-Multiplexing Trade-off (DMT) function. Two cases are considered. In the first case a transmitter knows the Channel State Information (CSI...

  7. NRC Information No. 88-14: Potential problems with electrical relays

    International Nuclear Information System (INIS)

    Rossi, C.E.

    1992-01-01

    This information notice is being provided to alert recipients to potential problems involving HFA, PVD 21B, PVD 21D, and HGA relays manufactured by General Electric Company (GE), as described below. Although some of these problems are several years old, they are included because utilities are still identifying problems discovered while implementing advice issued by GE in the early 1980s. The specific problem with the HFA relays concerns mechanical binding in the relay caused by incorrect location of a stop tab that is welded to the armature. The problems with the PVD 21B, PVD 21D, and HGA concern their seismic capability

  8. An RSS based location estimation technique for cognitive relay networks

    KAUST Repository

    Qaraqe, Khalid A.; Hussain, Syed Imtiaz; Ç elebi, Hasari Burak; Abdallah, Mohamed M.; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, a received signal strength (RSS) based location estimation method is proposed for a cooperative wireless relay network where the relay is a cognitive radio. We propose a method for the considered cognitive relay network to determine

  9. Properties of Risk Measures of Generalized Entropy in Portfolio Selection

    Directory of Open Access Journals (Sweden)

    Rongxi Zhou

    2017-12-01

    Full Text Available This paper systematically investigates the properties of six kinds of entropy-based risk measures: Information Entropy and Cumulative Residual Entropy in the probability space, Fuzzy Entropy, Credibility Entropy and Sine Entropy in the fuzzy space, and Hybrid Entropy in the hybridized uncertainty of both fuzziness and randomness. We discover that none of the risk measures satisfy all six of the following properties, which various scholars have associated with effective risk measures: Monotonicity, Translation Invariance, Sub-additivity, Positive Homogeneity, Consistency and Convexity. Measures based on Fuzzy Entropy, Credibility Entropy, and Sine Entropy all exhibit the same properties: Sub-additivity, Positive Homogeneity, Consistency, and Convexity. These measures based on Information Entropy and Hybrid Entropy, meanwhile, only exhibit Sub-additivity and Consistency. Cumulative Residual Entropy satisfies just Sub-additivity, Positive Homogeneity, and Convexity. After identifying these properties, we develop seven portfolio models based on different risk measures and made empirical comparisons using samples from both the Shenzhen Stock Exchange of China and the New York Stock Exchange of America. The comparisons show that the Mean Fuzzy Entropy Model performs the best among the seven models with respect to both daily returns and relative cumulative returns. Overall, these results could provide an important reference for both constructing effective risk measures and rationally selecting the appropriate risk measure under different portfolio selection conditions.

  10. Application of the voltage biased digital relay for the optimal protection of high inertia drive induction motors

    International Nuclear Information System (INIS)

    Choi, D. B.

    1999-01-01

    This paper describes typical protection schemes for large-size high inertia drive motor that are generally rotor thermal limited. Difficult and variable starting conditions of the large-size high inertia drive motor and compromises in the selection and setting of the protective devices are frequently encountered. The motors that typically encounter severe starting duty and present difficulties in achieving full motor protection are reactor coolant pumps (RCPs), blowers and compressors. For difficult starting conditions that are encountered by the large-size high inertia drive motors, state-of-the-art computer based calculations are capable of providing realistic predictions of the band of margin available for applying the protective relay. Based on the analysis of starting characteristics of large-size high inertia drive motors, this paper recommends that the optimal protection scheme for high inertia drive motors for nuclear power plants can be achieved by using the voltage biased digital relay instead of a speed switch and conventional overcurrent relays. (author)

  11. System for Relay Protection Command Transmission by High-Voltage Lines

    Directory of Open Access Journals (Sweden)

    D. A. Yenkov

    2009-01-01

    Full Text Available Development of a system for relay protection command transmission by high-voltage lines is shown in the paper. The paper describes an architecture of the system, main principles of its operation, engineering aspects of the development that is accomplishment of technical requirements, solution of trades-off. Justification of the selected design and an algorithm of the reliable detection of relay protection signals are given in the paper.

  12. Dangers of bypassing thermal overload relays in nuclear power plant motor operated valve circuits

    International Nuclear Information System (INIS)

    Baxter, F.D.

    1980-01-01

    Operation of motor operated valves is analyzed under various abnormal conditions such as frozen bearing, tight packing, mid-travel obstruction, torque switch failure, limit switch failure, and post-accident operation. Each condition has been reviewed to show that an adverse situation results if the thermal overload relays in the circuit are bypassed. In conclusion, there appears to be no technical basis for bypassing or oversizing the thermal overload relay provided it is selected correctly

  13. Power Allocation Strategies for Fixed-Gain Half-Duplex Amplify-and-Forward Relaying in Nakagami-m Fading

    KAUST Repository

    Zafar, Ammar

    2013-09-01

    In this paper, we study power allocation strategies for a fixed-gain amplify-and-forward relay network employing multiple relays. We consider two optimization problems for the relay network: 1) maximizing the end-to-end signalto- noise ratio (SNR) and 2) minimizing the total power consumption while maintaining the end-to-end SNR over a threshold value. We investigate these two problems for two relaying protocols of all-participate (AP) relaying and selective relaying and two cases of feedback to the relays, full and limited. We show that the SNR maximization problem is concave and the power minimization problem is convex for all protocols and feedback cases considered. We obtain closed-form expressions for the two problems in the case of full feedback and solve the problems through convex programming for limited feedback. Numerical results show the benefit of having full feedback at the relays for both optimization problems. However, they also show that feedback overhead can be reduced by having only limited feedback to the relays with only a small degradation in performance.

  14. Microcomputer relay regulator in the CAMAC standard

    International Nuclear Information System (INIS)

    Nikolaev, V.P.

    1984-01-01

    The digital relay regulator is developed on the base of the KM001 microcomputer and KK06 controller for automatic control ob ects with transfer functions describing a broad class of systems using actuating motors (stabilitation, follow-up systems). The CAMAC relay-unit realizes the regulation law and provides the possibility to control analogous values by 8 channels

  15. Statistical mechanics of sparse generalization and graphical model selection

    International Nuclear Information System (INIS)

    Lage-Castellanos, Alejandro; Pagnani, Andrea; Weigt, Martin

    2009-01-01

    One of the crucial tasks in many inference problems is the extraction of an underlying sparse graphical model from a given number of high-dimensional measurements. In machine learning, this is frequently achieved using, as a penalty term, the L p norm of the model parameters, with p≤1 for efficient dilution. Here we propose a statistical mechanics analysis of the problem in the setting of perceptron memorization and generalization. Using a replica approach, we are able to evaluate the relative performance of naive dilution (obtained by learning without dilution, following by applying a threshold to the model parameters), L 1 dilution (which is frequently used in convex optimization) and L 0 dilution (which is optimal but computationally hard to implement). Whereas both L p diluted approaches clearly outperform the naive approach, we find a small region where L 0 works almost perfectly and strongly outperforms the simpler to implement L 1 dilution

  16. Selecting a general-purpose data compression algorithm

    Science.gov (United States)

    Mathews, Gary Jason

    1995-01-01

    The National Space Science Data Center's Common Data Formate (CDF) is capable of storing many types of data such as scalar data items, vectors, and multidimensional arrays of bytes, integers, or floating point values. However, regardless of the dimensionality and data type, the data break down into a sequence of bytes that can be fed into a data compression function to reduce the amount of data without losing data integrity and thus remaining fully reconstructible. Because of the diversity of data types and high performance speed requirements, a general-purpose, fast, simple data compression algorithm is required to incorporate data compression into CDF. The questions to ask are how to evaluate and compare compression algorithms, and what compression algorithm meets all requirements. The object of this paper is to address these questions and determine the most appropriate compression algorithm to use within the CDF data management package that would be applicable to other software packages with similar data compression needs.

  17. Bilayer expurgated LDPC codes with uncoded relaying

    Directory of Open Access Journals (Sweden)

    Md. Noor-A-Rahim

    2017-08-01

    Full Text Available Bilayer low-density parity-check (LDPC codes are an effective coding technique for decode-and-forward relaying, where the relay forwards extra parity bits to help the destination to decode the source bits correctly. In the existing bilayer coding scheme, these parity bits are protected by an error correcting code and assumed reliably available at the receiver. We propose an uncoded relaying scheme, where the extra parity bits are forwarded to the destination without any protection. Through density evolution analysis and simulation results, we show that our proposed scheme achieves better performance in terms of bit erasure probability than the existing relaying scheme. In addition, our proposed scheme results in lower complexity at the relay.

  18. On Alternate Relaying with Improper Gaussian Signaling

    KAUST Repository

    Gaafar, Mohamed

    2016-06-06

    In this letter, we investigate the potential benefits of adopting improper Gaussian signaling (IGS) in a two-hop alternate relaying (AR) system. Given the known benefits of using IGS in interference-limited networks, we propose to use IGS to relieve the inter-relay interference (IRI) impact on the AR system assuming no channel state information is available at the source. In this regard, we assume that the two relays use IGS and the source uses proper Gaussian signaling (PGS). Then, we optimize the degree of impropriety of the relays signal, measured by the circularity coefficient, to maximize the total achievable rate. Simulation results show that using IGS yields a significant performance improvement over PGS, especially when the first hop is a bottleneck due to weak source-relay channel gains and/or strong IRI.

  19. On Alternate Relaying with Improper Gaussian Signaling

    KAUST Repository

    Gaafar, Mohamed; Amin, Osama; Ikhlef, Aissa; Chaaban, Anas; Alouini, Mohamed-Slim

    2016-01-01

    In this letter, we investigate the potential benefits of adopting improper Gaussian signaling (IGS) in a two-hop alternate relaying (AR) system. Given the known benefits of using IGS in interference-limited networks, we propose to use IGS to relieve the inter-relay interference (IRI) impact on the AR system assuming no channel state information is available at the source. In this regard, we assume that the two relays use IGS and the source uses proper Gaussian signaling (PGS). Then, we optimize the degree of impropriety of the relays signal, measured by the circularity coefficient, to maximize the total achievable rate. Simulation results show that using IGS yields a significant performance improvement over PGS, especially when the first hop is a bottleneck due to weak source-relay channel gains and/or strong IRI.

  20. Setting value optimization method in integration for relay protection based on improved quantum particle swarm optimization algorithm

    Science.gov (United States)

    Yang, Guo Sheng; Wang, Xiao Yang; Li, Xue Dong

    2018-03-01

    With the establishment of the integrated model of relay protection and the scale of the power system expanding, the global setting and optimization of relay protection is an extremely difficult task. This paper presents a kind of application in relay protection of global optimization improved particle swarm optimization algorithm and the inverse time current protection as an example, selecting reliability of the relay protection, selectivity, quick action and flexibility as the four requires to establish the optimization targets, and optimizing protection setting values of the whole system. Finally, in the case of actual power system, the optimized setting value results of the proposed method in this paper are compared with the particle swarm algorithm. The results show that the improved quantum particle swarm optimization algorithm has strong search ability, good robustness, and it is suitable for optimizing setting value in the relay protection of the whole power system.

  1. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end biterror rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. ©2010 IEEE.

  2. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-10-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end biterror rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. ©2010 IEEE.

  3. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

  4. Effects of Distributed Generation on Overcurrent Relay Coordination and an Adaptive Protection Scheme

    Science.gov (United States)

    Ilik, Semih C.; Arsoy, Aysen B.

    2017-07-01

    Integration of distributed generation (DG) such as renewable energy sources to electrical network becomes more prevalent in recent years. Grid connection of DG has effects on load flow directions, voltage profile, short circuit power and especially protection selectivity. Applying traditional overcurrent protection scheme is inconvenient when system reliability and sustainability are considered. If a fault happens in DG connected network, short circuit contribution of DG, creates additional branch element feeding the fault current; compels to consider directional overcurrent (OC) protection scheme. Protection coordination might get lost for changing working conditions when DG sources are connected. Directional overcurrent relay parameters are determined for downstream and upstream relays when different combinations of DG connected singular or plural, on radial test system. With the help of proposed flow chart, relay parameters are updated and coordination between relays kept sustained for different working conditions in DigSILENT PowerFactory program.

  5. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2011-06-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

  6. Design and Implementation of O/C relay using Microprocessor

    Directory of Open Access Journals (Sweden)

    Dr.Abdul-Sattar H. Jasim

    2012-03-01

    Full Text Available This work presents the design and implementation of a versatile digital overcurrent (O/C relay using a single microprocessor. The relay is implemented by a combination of a look-up table and a counter. The software development and hardware testing are done using a microcomputer module based on a 8-bit microprocessor. The digital processing of measured currents enables a separate setting of operating values selection of all types of inverse or constant time characteristics overcurrent protection. This protection provides reasonably fast tripping, even at terminal close to the power source were the most serve faults can occur excluding the transient condition. So this method has an excellent compromise between accuracy hardware and speed

  7. The Impact of TCSC on IDMT Relays in SLG Fault in Distribution Networks

    Directory of Open Access Journals (Sweden)

    Lazhar Bougouffa

    2016-03-01

    Full Text Available IDMT Directional Over-Current Relays protection is one of the basic protective relaying for distribution systems, for fault detection and clearing as soon as possible. Its function would generally be changed in presence of FACTS devices. In this paper a study to investigate the direct effect of varying reactance of the TCSC on single-line-to-ground (SLG fault in compensated distribution systems. This paper, therefore presents the calculation of fault component, and directional over-current relay operating time characteristics for phase-to-earth fault involving the TCSC. The case study is compared between compensated and uncompensated system. The coordination of the relays is a nonlinear programming problem and it is solved by using MATLAB software.

  8. Proportional fair scheduling with superposition coding in a cellular cooperative relay system

    DEFF Research Database (Denmark)

    Kaneko, Megumi; Hayashi, Kazunori; Popovski, Petar

    2013-01-01

    Many works have tackled on the problem of throughput and fairness optimization in cellular cooperative relaying systems. Considering firstly a two-user relay broadcast channel, we design a scheme based on superposition coding (SC) which maximizes the achievable sum-rate under a proportional...... fairness constraint. Unlike most relaying schemes where users are allocated orthogonally, our scheme serves the two users simultaneously on the same time-frequency resource unit by superposing their messages into three SC layers. The optimal power allocation parameters of each SC layer are derived...... by analysis. Next, we consider the general multi-user case in a cellular relay system, for which we design resource allocation algorithms based on proportional fair scheduling exploiting the proposed SC-based scheme. Numerical results show that the proposed algorithms allowing simultaneous user allocation...

  9. Time of arrival based location estimation for cooperative relay networks

    KAUST Repository

    Çelebi, Hasari Burak

    2010-09-01

    In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct links and amplification factor and location of the relay node on average CRLB are investigated. Simulation results show that the channel fading of both relay and direct links and amplification factor and location of relay node affect the accuracy of TOA based location estimation. ©2010 IEEE.

  10. Time of arrival based location estimation for cooperative relay networks

    KAUST Repository

    Ç elebi, Hasari Burak; Abdallah, Mohamed M.; Hussain, Syed Imtiaz; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct links and amplification factor and location of the relay node on average CRLB are investigated. Simulation results show that the channel fading of both relay and direct links and amplification factor and location of relay node affect the accuracy of TOA based location estimation. ©2010 IEEE.

  11. LTE-Advanced Relay Technology and Standardization

    CERN Document Server

    Yuan, Yifei

    2013-01-01

    LTE-Advanced Relay Technology and Standardization provides a timely reference work for relay technology with the finalizing of LTE Release 10 specifications. LTE-Advanced is quickly becoming the global standard for 4G cellular communications. The relay technology, as one of the key features in LTE-Advanced, helps not only to improve the system coverage and capacity, but also to save the costs of laying wireline backhaul. As a leading researcher in the field of LTE-Advanced standards, the author provides an in-depth description of LTE-A relay technology, and explains in detail the standard specification and design principles.     Readers from both academic and industrial fields can find sections of interest to them: Sections 2 & 4 could benefit researchers in academia and those who are engaged in exploratory work, while Sections 3 & 4 are more useful to engineers. Dr. Yifei Yuan is the Technical Director at the Standards Department of ZTE Inc.

  12. Reversal thyristor-relay direct current commutator

    International Nuclear Information System (INIS)

    Ivanenko, A.I.

    1982-01-01

    A thyristor-relay commutator used for alteration of the leading magnetic field direction in experiments with polarized neutrons is described. The commutator flowsheet is presented. Thyristors, connected so as to allow the relay trigger operation mode, are used as controllable electronic relay. Two connected in series coils with the total inductance of the order of 0.28 H serve as the electronic relay load. The arc-free current commutation is effected at the moment of the minimal current across the load terminals, which allows to easily reverse the current up to 10 A at a volatage, v <= 150 V. The experience gained within a year of operation has shown that the commutator meets the requirements of reliability and tuning

  13. Implementation of selective prevention for cardiometabolic diseases; are Dutch general practices adequately prepared?

    Science.gov (United States)

    Stol, Daphne M; Hollander, Monika; Nielen, Markus M J; Badenbroek, Ilse F; Schellevis, François G; de Wit, Niek J

    2018-03-01

    Current guidelines acknowledge the need for cardiometabolic disease (CMD) prevention and recommend five-yearly screening of a targeted population. In recent years programs for selective CMD-prevention have been developed, but implementation is challenging. The question arises if general practices are adequately prepared. Therefore, the aim of this study is to assess the organizational preparedness of Dutch general practices and the facilitators and barriers for performing CMD-prevention in practices currently implementing selective CMD-prevention. Observational study. Dutch primary care. General practices. Organizational characteristics. General practices implementing selective CMD-prevention are more often organized as a group practice (49% vs. 19%, p = .000) and are better organized regarding chronic disease management compared to reference practices. They are motivated for performing CMD-prevention and can be considered as 'frontrunners' of Dutch general practices with respect to their practice organization. The most important reported barriers are a limited availability of staff (59%) and inadequate funding (41%). The organizational infrastructure of Dutch general practices is considered adequate for performing most steps of selective CMD-prevention. Implementation of prevention programs including easily accessible lifestyle interventions needs attention. All stakeholders involved share the responsibility to realize structural funding for programmed CMD-prevention. Aforementioned conditions should be taken into account with respect to future implementation of selective CMD-prevention. Key Points   There is need for adequate CMD prevention. Little is known about the organization of selective CMD prevention in general practices.   • The organizational infrastructure of Dutch general practices is adequate for performing most steps of selective CMD prevention.   • Implementation of selective CMD prevention programs including easily accessible

  14. Evaluation of Harmonics Impact on Digital Relays

    Directory of Open Access Journals (Sweden)

    Kinan Wannous

    2018-04-01

    Full Text Available This paper presents the concept of the impact of harmonic distortion on a digital protection relay. The aim is to verify and determine the reasons of a mal-trip or failure to trip the protection relays; the suggested solution of the harmonic distortion is explained by a mathematical model in the Matlab Simulink programming environment. The digital relays have been tested under harmonic distortions in order to verify the function of the relays algorithm under abnormal conditions. The comparison between the protection relay algorithm under abnormal conditions and a mathematical model in the Matlab Simulink programming environment based on injected harmonics of high values is provided. The test is separated into different levels; the first level is based on the harmonic effect of an individual harmonic and mixed harmonics. The test includes the effect of the harmonics in the location of the fault point into distance protection zones. This paper is a new proposal in the signal processing of power quality disturbances using Matlab Simulink and the power quality impact on the measurements of the power system quantities; the test simulates the function of protection in power systems in terms of calculating the current and voltage values of short circuits and their faults. The paper includes several tests: frequency variations and decomposition of voltage waveforms with Fourier transforms (model and commercial relay, the effect of the power factor on the location of fault points, the relation between the tripping time and the total harmonic distortion (THD levels in a commercial relay, and a comparison of the THD capture between the commercial relay and the model.

  15. Cognitive relaying and power allocation under channel state uncertainties

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2013-04-01

    In this paper, we present robust joint relay precoder designs and transceiver power allocations for a cognitive radio network under imperfect channel state information (CSI). The secondary (or cognitive) network consists of a pair of single-antenna transceiver nodes and a non-regenerative two-way relay with multiple antennas which aids the communication process between the transceiver pair. The secondary nodes share the spectrum with a licensed primary user (PU) while guaranteeing that the interference to the PU receiver is maintained below a specified threshold. We consider two robust designs: the first is based on the minimization of the total transmit power of the secondary relay node required to provide the minimum quality of service, measured in terms of mean-square error (MSE) of the transceiver nodes, and the second is based on the minimization of the sum-MSE of the transceiver nodes. The robust designs are based on worst-case optimization and take into account known parameters of the error in the CSI to render the performance immune to the presence of errors in the CSI. Though the original problem is non-convex, we show that the proposed designs can be reformulated as tractable convex optimization problems that can be solved efficiently. We illustrate the performance of the proposed designs through some selected numerical simulations. © 2013 IEEE.

  16. Relay testing parametric investigation of seismic fragility

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Hofmayer, C.; Kassir, M.; Pepper, S.

    1989-01-01

    The seismic capacity of most electrical equipment is governed by malfunction of relays. An evaluation of the existing relay test data base at Brookhaven National Laboratory (BNL) has indicated that the seismic fragility of a relay may depend on various parameters related to the design or the input motion. In particular, the electrical mode, contact state, adjustment, chatter duration acceptance limit, and the frequency and the direction of the vibration input have been considered to influence the relay fragility level. For a particular relay type, the dynamics of its moving parts depends on the exact model number and vintage and hence, these parameters may also influence the fragility level. In order to investigate the effect of most of these parameters on the seismic fragility level, BNL has conducted a relay test program. The testing has been performed at Wyle Laboratories. Establishing the correlation between the single frequency fragility test input and the corresponding multifrequency response spectrum (TRS) is also an objective of this test program. This paper discusses the methodology used for testing and presents a brief summary of important test results. 1 ref., 10 figs

  17. Airborne relay-based regional positioning system.

    Science.gov (United States)

    Lee, Kyuman; Noh, Hongjun; Lim, Jaesung

    2015-05-28

    Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the pseudolites are mounted, and this causes performance degradation. To address these pseudolite system limitations, we propose an airborne relay-based regional positioning system that consists of a master station, reference stations, airborne relays and a user. In the proposed system, navigation signals are generated from the reference stations located on the ground and are relayed via the airborne relays. Unlike in conventional airborne-based systems, the user in the proposed system sequentially estimates both the locations of airborne relays and his/her own position. Therefore, a delay due to monitoring does not occur, and the accuracy is not affected by the movement of airborne relays. We conducted several simulations to evaluate the performance of the proposed system. Based on the simulation results, we demonstrated that the proposed system guarantees a higher accuracy than airborne-based pseudolite systems, and it is feasible despite the existence of clock offsets among reference stations.

  18. Relay Runners Catch The Rays

    CERN Multimedia

    2004-01-01

    Athletes sizzled around CERN on Wednesday 19 May at the 34th annual relay race. On one of the warmest days of the year so far, sunkissed competitors ran for the finish line and then straight for the drinks table. The Shabbys were on fire again, hurtling across the line first in a time of 10 min. 42.6 sec. and making an even stronger claim to being hailed as the traditional winners of the race with their fourth triumph in a row. Also on form were the Lynx Runners who won the Veteran's trophy, continuing their winning ways since 2002 and placing 29th overall. Ildefons Magrans of the ALICE Quarks on the Loose team ran the fastest 1000m in a time of 2 min. 47 sec. Second-placed Charmilles Technologies won the Open category in a time of 11 min. 03 sec., taking the prize for teams whose members work in different departments or who come from outside CERN. The OPALadies won the women's trophy and placed 48th. With 9 trophies up for grabs, more than 300 people in 55 teams ran the fun run, covering distances of 1000m ...

  19. Physical Layer Security Using Two-Path Successive Relaying

    Directory of Open Access Journals (Sweden)

    Qian Yu Liau

    2016-06-01

    Full Text Available Relaying is one of the useful techniques to enhance wireless physical-layer security. Existing literature shows that employing full-duplex relay instead of conventional half-duplex relay improves secrecy capacity and secrecy outage probability, but this is at the price of sophisticated implementation. As an alternative, two-path successive relaying has been proposed to emulate operation of full-duplex relay by scheduling a pair of half-duplex relays to assist the source transmission alternately. However, the performance of two-path successive relaying in secrecy communication remains unexplored. This paper proposes a secrecy two-path successive relaying protocol for a scenario with one source, one destination and two half-duplex relays. The relays operate alternately in a time division mode to forward messages continuously from source to destination in the presence of an eavesdropper. Analytical results reveal that the use of two half-duplex relays in the proposed scheme contributes towards a quadratically lower probability of interception compared to full-duplex relaying. Numerical simulations show that the proposed protocol achieves the ergodic achievable secrecy rate of full-duplex relaying while delivering the lowest probability of interception and secrecy outage probability compared to the existing half duplex relaying, full duplex relaying and full duplex jamming schemes.

  20. CERN Relay Race: a great success!

    CERN Multimedia

    Staff Association

    2016-01-01

    On Thursday May 19, the traditional relay race was held at CERN, organised jointly by the Running Club and the CERN Staff Association. In spite of the less than optimal weather, the 127 registered teams were not discouraged. Warmed by their efforts on the roads of CERN, the participants were able to withstand the chilly May weather. The start signal for the race was given by our Director General, demonstrating the interest in this event at the highest level of the Organization. Thank you for this much appreciated commitment! Can we hope for next year to see a team from the Directorate in the race? The many spectators who had come to cheer on the runners could also visit the stalls staffed by a few clubs and some of Interfon’s commercial partners. Refreshment and food stands contributed to the friendly atmosphere. The organisation of such an event requires however a substantial investment in order to cover all aspects of logistics, from preparation before the race, to the actual establishment ...

  1. CERN Relay Race: a great success!

    CERN Multimedia

    Staff Association

    2017-01-01

    Thursday 1st June marked the traditional Relay Race at CERN, organised jointly by the Running Club and the CERN Staff Association. Once again, the Race lived up to the expectations and the number of participants came close to last year’s all-time high with no less than 715 entries across different categories! In total 116 teams of 6 runners and 19 walkers completed the course at the Meyrin site in bright sunshine. Congratulations to all of them! Our Director-General gave the starting signal for the Race, demonstrating the interest in this event at the highest level of the Organization. Thank you for this much appreciated commitment! Moreover, a number of very high-level runners came to spice up this 2017 edition. The 1000-meter race was a tight one between Alexandre Roche (top 5 in the “Tour du canton”) and Baptiste Fieux who tore up the race at 2’36 and 2’42 respectively. Baptiste passed the baton to Pierre Baqué, the winner of the 2015 Saint&a...

  2. Performance Analysis of Secondary Link with Cross-Layer Design and Cooperative Relay in Cognitive Radio Networks

    KAUST Repository

    Ma, Hao

    2012-06-01

    In this thesis, we investigate two different system infrastructures in underlay cognitive radio network, in which two popular techniques, cross-layer design and cooperative communication, are considered, respectively. In particular, we introduce the Aggressive Adaptive Modulation and Coding (A-AMC) into the cross-layer design and achieve the optimal boundary points in closed form to choose the AMC and A-AMC transmission modes by taking into account the Channel State Information (CSI) from the secondary transmitter to both the primary receiver and the secondary receiver. What’s more, for the cooperative communication design, we consider three different relay selection schemes: Partial Relay Selection, Opportunistic Relay Selection and Threshold Relay Selection. The Probability Density Functions (PDFs) of the Signal-to- Noise Ratio (SNR) in each hop for different selection schemes are provided, and then the exact closed-form expressions for the end-to-end packet loss rate in the secondary link considering the cooperation of the Decode-and-Forward (DF) relay for different relay selection schemes are derived.

  3. Outage performance of opportunistic two-way amplify-and-forward relaying with outdated channel state information

    KAUST Repository

    Hwang, Kyusung

    2013-09-01

    In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we propose a single relay selection scheme in AF-based TWR system under outdated CSI conditions. With this policy, we offer a statistical analysis of the signal-to-noise ratio per hop and analyze the outage probability with asymmetric outage thresholds based on CSI-assisted AF protocol. Additionally, we provide the exact and asymptotic expressions based on the provided statistical/joint statistical analyses of a dual-hop AF transmission. Finally, we verify our analytical results with some selected computer-based simulation results. © 1972-2012 IEEE.

  4. Subset selection from Type-I and Type-II generalized logistic populations

    NARCIS (Netherlands)

    Laan, van der M.J.; Laan, van der P.

    1996-01-01

    We give an introduction to the logistic and generalized logistic distributions. We obtain exact results for the probability of correct selection from Type-I and Type-II generalized logistic populations which only differ in their location parameter. Some open problems are formulated.

  5. On the achievable degrees of freedom of alternate MIMO relaying with multiple AF relays

    KAUST Repository

    Park, Kihong; Alouini, Mohamed-Slim; Park, Seongho; Ko, Youngchai

    2012-01-01

    In this paper, we consider a two-hop relaying network where one source, one destination, and multiple amplify-and-forward (AF) relays equipped with M antennas operate in a half-duplex mode. In order to compensate for the inherent loss of capacity

  6. Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

    Directory of Open Access Journals (Sweden)

    Xianwen He

    2017-01-01

    Full Text Available We consider the training design and channel estimation in the amplify-and-forward (AF diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI of second-hop link due to the multiaccess interference (MAI and cooperative data interference (CDI. To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

  7. Iterative Relay Scheduling with Hybrid ARQ under Multiple User Equipment (Type II) Relay Environments

    KAUST Repository

    Nam, Sung Sik; Alouini, Mohamed-Slim; Choi, Seyeong

    2018-01-01

    -generation cellular systems (e.g., LTE-Advanced and beyond). The proposed IRS-HARQ aims to increase the achievable data rate by iteratively scheduling a relatively better UE relay closer to the end user in a probabilistic sense, provided that the relay-to-end user

  8. Capacity Bounds and Mapping Design for Binary Symmetric Relay Channels

    Directory of Open Access Journals (Sweden)

    Majid Nasiri Khormuji

    2012-12-01

    Full Text Available Capacity bounds for a three-node binary symmetric relay channel with orthogonal components at the destination are studied. The cut-set upper bound and the rates achievable using decode-and-forward (DF, partial DF and compress-and-forward (CF relaying are first evaluated. Then relaying strategies with finite memory-length are considered. An efficient algorithm for optimizing the relay functions is presented. The Boolean Fourier transform is then employed to unveil the structure of the optimized mappings. Interestingly, the optimized relay functions exhibit a simple structure. Numerical results illustrate that the rates achieved using the optimized low-dimensional functions are either comparable to those achieved by CF or superior to those achieved by DF relaying. In particular, the optimized low-dimensional relaying scheme can improve on DF relaying when the quality of the source-relay link is worse than or comparable to that of other links.

  9. Discrete radioisotopic relays of a cyclic action

    International Nuclear Information System (INIS)

    Klempner, K.S.; Vasil'ev, A.G.

    1975-01-01

    A functional diagram of discrete radioisotopic relay equipment (RRP) with cyclic action was examined. An analysis of its rapid action and reliability under stationary conditions and transition regimes is presented. A structural diagram of radioisotopic relay equipment shows three radiation detectors, a pulse standardizer, an integrator and a power amplifier with a threshold cut-off device. It was established that the basic properties of the RRP - rapid action and reliability - are determined entirely by the counting rate of the average frequency of pulses from the radiation detector, n 0 and n 1 , in the 0 and 1 states (absence of current in the electromagnetic relay winding and activation of the winding of the output relay), capacities N 1 and N 2 of the dual counters, and the frequency of the transition threshold, f, of the generator. Formulas are presented which allow making engineering calculations for determining the optimum RRP parameters. High speed and reliability are shown, which are determined by the production purposes of the relay

  10. Cognitive Relay Networks: A Comprehensive Survey

    Directory of Open Access Journals (Sweden)

    Ayesha Naeem

    2015-07-01

    Full Text Available Cognitive radio is an emerging technology to deal with the scarcity and requirement of radio spectrum by dynamically assigning spectrum to unlicensed user . This revolutionary technology shifts the paradigm in the wireless system design by all owing unlicensed user the ability to sense, adapt and share the dynamic spectrum. Cognitive radio technology have been applied to different networks and applications ranging from wireless to public saf ety, smart grid, medical, rela y and cellular applications to increase the throughput and spectrum efficiency of the network. Among these applications, cognitive relay networks is one of the application where cognitive radio technology has been applied. Cognitiv e rela y network increases the network throughput by reducing the complete pa th loss and also by ensuring cooper ation among secondary users and cooperation among primary and secondary users. In this paper , our aim is to provide a survey on cognitive relay network. We also provide a detailed review on existing schemes in cognitive relay networks on the basis of relaying protocol, relay cooperation and channel model.

  11. Counterfactual quantum cryptography network with untrusted relay

    Science.gov (United States)

    Chen, Yuanyuan; Gu, Xuemei; Jiang, Dong; Xie, Ling; Chen, Lijun

    2015-07-01

    Counterfactual quantum cryptography allows two remote parties to share a secret key even though a physical particle is not in fact transmitted through the quantum channel. In order to extend the scope of counterfactual quantum cryptography, we use an untrusted relay to construct a multi-user network. The implementation issues are discussed to show that the scheme can be realized with current technologies. We also prove the practical security advantages of the scheme by eliminating the probability that an eavesdropper can directly access the signal or an untrusted relay can perform false operations.

  12. CERN Relay Race: information for drivers

    CERN Multimedia

    2012-01-01

    The CERN relay race will take place around the Meyrin site on Thursday, 24 May starting at 12.15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. In addition, there will be a Nordic Walking event which will finish around 12.50. This should not block the roads, but please drive carefully during this time. Thank you for your cooperation. Details on how to register your team for the relay race can be found here.

  13. Deep space optical communication via relay satellite

    Science.gov (United States)

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  14. Combined Rate and Power Allocation with Link Scheduling in Wireless Data Packet Relay Networks with Fading Channels

    OpenAIRE

    Subhrakanti Dey; Minyi Huang

    2007-01-01

    We consider a joint rate and power control problem in a wireless data traffic relay network with fading channels. The optimization problem is formulated in terms of power and rate selection, and link transmission scheduling. The objective is to seek high aggregate utility of the relay node when taking into account buffer load management and power constraints. The optimal solution for a single transmitting source is computed by a two-layer dynamic programming algorithm which leads to optimal ...

  15. UPDATE ON THE SELECTION OF THE FUTURE DIRECTOR-GENERAL AT CERN

    CERN Document Server

    2002-01-01

    In September 2002 the Committee of Council decided, in accordance with the selection procedure it adopted in 2000, to interview the candidate proposed by the Search Committee for the post of future Director-General. The Committee of Council conducted this interview on 14 November 2002. The selection procedure is moving forward, and it is expected that the conditions allowing the Council to make a decision on the nomination will be satisfied in December 2002. The term of the next Director-General begins on 1 January 2004. Further information on the procedure will be communicated as it becomes available.

  16. Advanced Strategic and Tactical Relay Request Management for the Mars Relay Operations Service

    Science.gov (United States)

    Allard, Daniel A.; Wallick, Michael N.; Gladden, Roy E.; Wang, Paul; Hy, Franklin H.

    2013-01-01

    This software provides a new set of capabilities for the Mars Relay Operations Service (MaROS) in support of Strategic and Tactical relay, including a highly interactive relay request Web user interface, mission control over relay planning time periods, and mission management of allowed strategic vs. tactical request parameters. Together, these new capabilities expand the scope of the system to include all elements critical for Tactical relay operations. Planning of replay activities spans a time period that is split into two distinct phases. The first phase is called Strategic, which begins at the time that relay opportunities are identified, and concludes at the point that the orbiter generates the flight sequences for on board execution. Any relay request changes from this point on are called Tactical. Tactical requests, otherwise called Orbit - er Relay State Changes (ORSC), are highly restricted in terms of what types of changes can be made, and the types of parameters that can be changed may differ from one orbiter to the next. For example, one orbiter may be able to delay the start of a relay request, while another may not. The legacy approach to ORSC management involves exchanges of e-mail with "requests for change" and "acknowledgement of approval," with no other tracking of changes outside of e-mail folders. MaROS Phases 1 and 2 provided the infrastructure for strategic relay for all supported missions. This new version, 3.0, introduces several capabilities that fully expand the scope of the system to include tactical relay. One new feature allows orbiter users to manage and "lock" Planning Periods, which allows the orbiter team to formalize the changeover from Strategic to Tactical operations. Another major feature allows users to interactively submit tactical request changes via a Web user interface. A third new feature allows orbiter missions to specify allowed tactical updates, which are automatically incorporated into the tactical change process

  17. A guide to developing resource selection functions from telemetry data using generalized estimating equations and generalized linear mixed models

    Directory of Open Access Journals (Sweden)

    Nicola Koper

    2012-03-01

    Full Text Available Resource selection functions (RSF are often developed using satellite (ARGOS or Global Positioning System (GPS telemetry datasets, which provide a large amount of highly correlated data. We discuss and compare the use of generalized linear mixed-effects models (GLMM and generalized estimating equations (GEE for using this type of data to develop RSFs. GLMMs directly model differences among caribou, while GEEs depend on an adjustment of the standard error to compensate for correlation of data points within individuals. Empirical standard errors, rather than model-based standard errors, must be used with either GLMMs or GEEs when developing RSFs. There are several important differences between these approaches; in particular, GLMMs are best for producing parameter estimates that predict how management might influence individuals, while GEEs are best for predicting how management might influence populations. As the interpretation, value, and statistical significance of both types of parameter estimates differ, it is important that users select the appropriate analytical method. We also outline the use of k-fold cross validation to assess fit of these models. Both GLMMs and GEEs hold promise for developing RSFs as long as they are used appropriately.

  18. Dr Fabiola Gianotti has been selected by CERN Council to become next CERN Director General

    CERN Multimedia

    Brice, Maximilien

    2014-01-01

    With the next Director-General announced, watch the press conference starting in a few minutes via http://cern.ch/webcast/ and send your questions via Twitter to @CERNpressoffice CERN Council selects Italian physicist, Dr Fabiola Gianotti, as CERN’s next Director-General. Dr Gianotti’s mandate will begin on 1 January 2016 and run for a period of five years, read more: http://cern.ch/go/tN09F

  19. Relay communications strategies for Mars exploration through 2020

    Science.gov (United States)

    Edwards, Charles D., Jr.; Arnold, B.; DePaula, R.; Kazz, G.; Lee, C.; Noreen, G.

    2005-01-01

    In this paper we will examine NASA's strategy for relay communications support of missions planned for this decade, and discuss options for longer-term relay network evolution in support of second-decade missions.

  20. Switched diversity strategies for dual-hop relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine; Alouini, Mohamed-Slim; Radaydeh, Redha M.

    2011-01-01

    This paper investigates the effect of different switched diversity configurations on the implementation complexity and achieved performance of dual-hop amplify-and-forward (AF) relaying networks. A low-complexity model of the relay station

  1. protective relay studies for the nigerian national electric 330 kv

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... protective relay schemes of the National Electric Power Authority. Some of the basic ... Nigerian special system characteristics, schemes to correct existing protection inadequacies .... relays buried in the transformer. A reach of ...

  2. Dynamic Relaying in 3GPP LTE-Advanced Networks

    Directory of Open Access Journals (Sweden)

    Van Phan Vinh

    2009-01-01

    Full Text Available Relaying is one of the proposed technologies for LTE-Advanced networks. In order to enable a flexible and reliable relaying support, the currently adopted architectural structure of LTE networks has to be modified. In this paper, we extend the LTE architecture to enable dynamic relaying, while maintaining backward compatibility with LTE Release 8 user equipments, and without limiting the flexibility and reliability expected from relaying. With dynamic relaying, relays can be associated with base stations on a need basis rather than in a fixed manner which is based only on initial radio planning. Proposals are also given on how to further improve a relay enhanced LTE network by enabling multiple interfaces between the relay nodes and their controlling base stations, which can possibly be based on technologies different from LTE, so that load balancing can be realized. This load balancing can be either between different base stations or even between different networks.

  3. Capacity gains of buffer-aided moving relays

    KAUST Repository

    Zafar, Ammar

    2017-03-14

    This work investigates the gain due to reduction in path loss by deploying buffer-aided moving relaying. In particular, the increase in gain due to moving relays is studied for dual-hop broadcast channels and the bidirectional relay channel. It is shown that the exploited gains in these channels due to buffer-aided relaying can be enhanced by utilizing the fact that a moving relay can communicate with the terminal closest to it and store the data in the buffer and then forward the data to the intended destination when it comes in close proximity with the destination. Numerical results show that for both the considered channels the achievable rates are increased as compared to the case of stationary relays. Numerical results also show that more significant increase in performance is seen when the relay moves to-and-fro between the source and the relay.

  4. Dynamic Relaying in 3GPP LTE-Advanced Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Van Phan, Vinh; Redana, Simone

    2009-01-01

    Relaying is one of the proposed technologies for LTE-Advanced networks. In order to enable a flexible and reliable relaying support, the currently adopted architectural structure of LTE networks has to be modified. In this paper, we extend the LTE architecture to enable dynamic relaying, while...... maintaining backward compatibility with LTE Release 8 user equipments, and without limiting the flexibility and reliability expected from relaying.With dynamic relaying, relays can be associated with base stations on a need basis rather than in a fixed manner which is based only on initial radio planning....... Proposals are also given on how to further improve a relay enhanced LTE network by enabling multiple interfaces between the relay nodes and their controlling base stations, which can possibly be based on technologies different from LTE, so that load balancing can be realized. This load balancing can...

  5. Improper Signaling for Virtual Full-Duplex Relay Systems

    KAUST Repository

    Gaafar, Mohamed

    2017-02-14

    Virtual full-duplex (VFD) is a powerful solution to compensate the rate loss of half-duplex relaying without the need to full-duplex capable nodes. Inter-relay interference (IRI) challenges the operation of VFD relaying systems. Recently, improper signaling is employed at both relays of the VFD to mitigate the IRI by imposing the same signal characteristics for both relays. To further boost the achievable rate performance, asymmetric time sharing VFD relaying system is adopted with different improper signals at the half-duplex relays. The joint tuning of the three design parameters improves the achievable rate performance at different ranges of IRI and different relays locations. Extensive simulation results are presented and analyzed to show the achievable rate gain of the proposed system and understand the system behavior.

  6. Improper Signaling for Virtual Full-Duplex Relay Systems

    KAUST Repository

    Gaafar, Mohamed; Amin, Osama; Schaefer, Rafael F.; Alouini, Mohamed-Slim

    2017-01-01

    Virtual full-duplex (VFD) is a powerful solution to compensate the rate loss of half-duplex relaying without the need to full-duplex capable nodes. Inter-relay interference (IRI) challenges the operation of VFD relaying systems. Recently, improper signaling is employed at both relays of the VFD to mitigate the IRI by imposing the same signal characteristics for both relays. To further boost the achievable rate performance, asymmetric time sharing VFD relaying system is adopted with different improper signals at the half-duplex relays. The joint tuning of the three design parameters improves the achievable rate performance at different ranges of IRI and different relays locations. Extensive simulation results are presented and analyzed to show the achievable rate gain of the proposed system and understand the system behavior.

  7. Capacity gains of buffer-aided moving relays

    KAUST Repository

    Zafar, Ammar; Shaqfeh, Mohammad; Alnuweiri, Hussein; Alouini, Mohamed-Slim

    2017-01-01

    This work investigates the gain due to reduction in path loss by deploying buffer-aided moving relaying. In particular, the increase in gain due to moving relays is studied for dual-hop broadcast channels and the bidirectional relay channel. It is shown that the exploited gains in these channels due to buffer-aided relaying can be enhanced by utilizing the fact that a moving relay can communicate with the terminal closest to it and store the data in the buffer and then forward the data to the intended destination when it comes in close proximity with the destination. Numerical results show that for both the considered channels the achievable rates are increased as compared to the case of stationary relays. Numerical results also show that more significant increase in performance is seen when the relay moves to-and-fro between the source and the relay.

  8. Relay protection features of frequency-adjustable electric drive

    Science.gov (United States)

    Kuprienko, V. V.

    2018-03-01

    The features of relay protection of high-voltage electric motors in composition of the frequency-adjustable electric drive are considered in the article. The influence of frequency converters on the stability of the operation of various types of relay protection used on electric motors is noted. Variants of circuits for connecting relay protection devices are suggested. The need to develop special relay protection devices for a frequency-adjustable electric drive is substantiated.

  9. Microprocessor protection relays: new prospects or new problems?

    OpenAIRE

    Gurevich, Vladimir

    2006-01-01

    The internal architecture and principles of operation of microprocessor-based devices including so-called "microprocessor protective relays" have little in common with devices called "electric relays". But microprocessor-based relay protection devices are gradually driving out the traditional electromechanical and even electronic relay protection of virtually from all fields of power and electrical engineering. Advantages of microprocessor-based protection means over traditional ones are far ...

  10. Wireless Power Transfer in Cooperative DF Relaying Networks with Log-Normal Fading

    KAUST Repository

    Rabie, Khaled M.

    2017-02-07

    Energy-harvesting (EH) and wireless power transfer in cooperative relaying networks have recently attracted a considerable amount of research attention. Most of the existing work on this topic however focuses on Rayleigh fading channels which represents outdoor environments. Unlike these studies, in this paper we analyze the performance of wireless power transfer in two-hop decode-and- forward (DF) cooperative relaying systems in indoor channels characterized by log-normal fading. Three well-known EH protocols are considered in our evaluations: a) time switching relaying (TSR), b) power splitting relaying (PSR) and c) ideal relaying receiver (IRR). The performance is evaluated in terms of the ergodic outage probability for which we derive accurate analytical expressions for the three systems under consideration. Results reveal that careful selection of the EH time and power splitting factors in the TSR- and PSR-based system are important to optimize performance. It is also presented that the optimized PSR system has near- ideal performance and that increasing the source transmit power and/or the energy harvester efficiency can further improve performance.

  11. Wireless Power Transfer in Cooperative DF Relaying Networks with Log-Normal Fading

    KAUST Repository

    Rabie, Khaled M.; Adebisi, Bamidele; Alouini, Mohamed-Slim

    2017-01-01

    Energy-harvesting (EH) and wireless power transfer in cooperative relaying networks have recently attracted a considerable amount of research attention. Most of the existing work on this topic however focuses on Rayleigh fading channels which represents outdoor environments. Unlike these studies, in this paper we analyze the performance of wireless power transfer in two-hop decode-and- forward (DF) cooperative relaying systems in indoor channels characterized by log-normal fading. Three well-known EH protocols are considered in our evaluations: a) time switching relaying (TSR), b) power splitting relaying (PSR) and c) ideal relaying receiver (IRR). The performance is evaluated in terms of the ergodic outage probability for which we derive accurate analytical expressions for the three systems under consideration. Results reveal that careful selection of the EH time and power splitting factors in the TSR- and PSR-based system are important to optimize performance. It is also presented that the optimized PSR system has near- ideal performance and that increasing the source transmit power and/or the energy harvester efficiency can further improve performance.

  12. Multi-Destination Cognitive Radio Relay Network with SWIPT and Multiple Primary Receivers

    KAUST Repository

    Al-Habob, Ahmed A.

    2017-05-12

    In this paper, we study the performance of simultaneous wireless information and power transfer (SWIPT) technique in a multi-destination dual-hop underlay cognitive relay network with multiple primary receivers. Information transmission from the secondary source to destinations is performed entirely via a decode- and-forward (DF) relay. The relay is assumed to have no embedded power source and to harvest energy from the source signal using a power splitting (PS) protocol and employing opportunistic scheduling to forward the information to the selected destination. We derive analytical expressions for the outage probability assuming Rayleigh fading channels and considering the energy harvesting efficiency at relay, the source maximum transmit power and primary receivers interference constraints. The system performance is also studied at high signal-to-noise ratio (SNR) values where approximate expressions for the outage probability are provided and analyzed in terms of diversity order and coding gain. Monte-Carlo simulations and some numerical examples are provided to validate the derived expressions and to illustrate the effect of various system parameters on the system performance. In contrast to their conventional counterparts where a multi- destination diversity is usually achieved, the results show that the multi-destination cognitive radio relay networks with the SWIPT technique achieve a constant diversity order of one.

  13. Maximizing Expected Achievable Rates for Block-Fading Buffer-Aided Relay Channels

    KAUST Repository

    Shaqfeh, Mohammad

    2016-05-25

    In this paper, the long-term average achievable rate over block-fading buffer-aided relay channels is maximized using a hybrid scheme that combines three essential transmission strategies, which are decode-and-forward, compress-and-forward, and direct transmission. The proposed hybrid scheme is dynamically adapted based on the channel state information. The integration and optimization of these three strategies provide a more generic and fundamental solution and give better achievable rates than the known schemes in the literature. Despite the large number of optimization variables, the proposed hybrid scheme can be optimized using simple closed-form formulas that are easy to apply in practical relay systems. This includes adjusting the transmission rate and compression when compress-and-forward is the selected strategy based on the channel conditions. Furthermore, in this paper, the hybrid scheme is applied to three different models of the Gaussian block-fading buffer-aided relay channels, depending on whether the relay is half or full duplex and whether the source and the relay have orthogonal or non-orthogonal channel access. Several numerical examples are provided to demonstrate the achievable rate results and compare them to the upper bounds of the ergodic capacity for each one of the three channel models under consideration.

  14. Maximizing Expected Achievable Rates for Block-Fading Buffer-Aided Relay Channels

    KAUST Repository

    Shaqfeh, Mohammad; Zafar, Ammar; Alnuweiri, Hussein; Alouini, Mohamed-Slim

    2016-01-01

    In this paper, the long-term average achievable rate over block-fading buffer-aided relay channels is maximized using a hybrid scheme that combines three essential transmission strategies, which are decode-and-forward, compress-and-forward, and direct transmission. The proposed hybrid scheme is dynamically adapted based on the channel state information. The integration and optimization of these three strategies provide a more generic and fundamental solution and give better achievable rates than the known schemes in the literature. Despite the large number of optimization variables, the proposed hybrid scheme can be optimized using simple closed-form formulas that are easy to apply in practical relay systems. This includes adjusting the transmission rate and compression when compress-and-forward is the selected strategy based on the channel conditions. Furthermore, in this paper, the hybrid scheme is applied to three different models of the Gaussian block-fading buffer-aided relay channels, depending on whether the relay is half or full duplex and whether the source and the relay have orthogonal or non-orthogonal channel access. Several numerical examples are provided to demonstrate the achievable rate results and compare them to the upper bounds of the ergodic capacity for each one of the three channel models under consideration.

  15. Exact outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, we investigate a dual-hop decode-andforward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we derive exact closed-form expression for the outage probability based on the exact statistics of each hop. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2010 IEEE.

  16. Exact outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-11-01

    In this paper, we investigate a dual-hop decode-andforward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we derive exact closed-form expression for the outage probability based on the exact statistics of each hop. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2010 IEEE.

  17. 49 CFR 236.52 - Relayed cut-section.

    Science.gov (United States)

    2010-10-01

    ..., MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Rules and Instructions: All Systems Track Circuits § 236.52 Relayed cut-section. Where relayed cut-section is used in... 49 Transportation 4 2010-10-01 2010-10-01 false Relayed cut-section. 236.52 Section 236.52...

  18. 76 FR 72124 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2011-11-22

    ... Docket No. 10-191; FCC 11-123] Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal..., the information collection associated with the Commission's Internet- Based Telecommunications Relay... Telecommunications Relay Service Numbering, CG Docket No. 03-123; WC Docket No. 05-196; WC Docket No. 10-191; FCC 11...

  19. 76 FR 65965 - Contributions to the Telecommunications Relay Services Fund

    Science.gov (United States)

    2011-10-25

    ...] Contributions to the Telecommunications Relay Services Fund AGENCY: Federal Communications Commission. ACTION... Telecommunications Relay Services (TRS) Fund in a manner prescribed by regulation that is consistent with and... . SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Contributions to the Telecommunications Relay...

  20. Asymmetric Modulation Gains in Network Coded Relay Networks

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2015-01-01

    Wireless relays have usually been considered in two ways. On the one hand, a physical layer approach focused on per-packet reliability and involving the relay on each packet transmission. On the other, recent approaches have relied on the judicious activation of the relay at the network level to ...

  1. A SDP based design of relay precoding for the power minimization of MIMO AF-relay networks

    KAUST Repository

    Rao, Anlei; Park, Kihong; Alouini, Mohamed-Slim

    2015-01-01

    Relay precoding for multiple-input and multiple-output (MIMO) relay networks has been approached by either optimizing the efficiency performance with given power consumption constraints or minimizing the power consumption with quality-of-service (Qo

  2. A general population genetic framework for antagonistic selection that accounts for demography and recurrent mutation.

    Science.gov (United States)

    Connallon, Tim; Clark, Andrew G

    2012-04-01

    Antagonistic selection--where alleles at a locus have opposing effects on male and female fitness ("sexual antagonism") or between components of fitness ("antagonistic pleiotropy")--might play an important role in maintaining population genetic variation and in driving phylogenetic and genomic patterns of sexual dimorphism and life-history evolution. While prior theory has thoroughly characterized the conditions necessary for antagonistic balancing selection to operate, we currently know little about the evolutionary interactions between antagonistic selection, recurrent mutation, and genetic drift, which should collectively shape empirical patterns of genetic variation. To fill this void, we developed and analyzed a series of population genetic models that simultaneously incorporate these processes. Our models identify two general properties of antagonistically selected loci. First, antagonistic selection inflates heterozygosity and fitness variance across a broad parameter range--a result that applies to alleles maintained by balancing selection and by recurrent mutation. Second, effective population size and genetic drift profoundly affect the statistical frequency distributions of antagonistically selected alleles. The "efficacy" of antagonistic selection (i.e., its tendency to dominate over genetic drift) is extremely weak relative to classical models, such as directional selection and overdominance. Alleles meeting traditional criteria for strong selection (N(e)s > 1, where N(e) is the effective population size, and s is a selection coefficient for a given sex or fitness component) may nevertheless evolve as if neutral. The effects of mutation and demography may generate population differences in overall levels of antagonistic fitness variation, as well as molecular population genetic signatures of balancing selection.

  3. Implementation of selective prevention for cardiometabolic diseases; is general practice adequately prepared ?

    NARCIS (Netherlands)

    Stol, D.M.; Hollander, M.; Nielen, M.M.J.; Badenbroek, I.F.; Schellevis, F.G.; Wit, N.J. de

    2018-01-01

    Objective: Current guidelines acknowledge the need for cardiometabolic disease (CMD) prevention and recommend five-yearly screening of a targeted population. In recent years programs for selective CMD-prevention have been developed, but implementation is challenging. The question arises if general

  4. SWIPT in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2017-02-09

    In this paper, we consider a multiuser multiple- input multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting relays and multiple destinations. Since the end-to-end sum rate maximization problem is intractable, we tackle a simplified problem where we maximize the sum of the harvested energy at the relays, we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relay- destination channels. The interference mitigation at the destinations is managed in two ways: either to fix the interference covariance matrices at the destination and update them at each iteration until convergence, or to cancel the interference using an algorithm similar to the BD method. We provide numerical results to show the relevance of our proposed solution.

  5. Modelling and Verification of Relay Interlocking Systems

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Bliguet, Marie Le; Kjær, Andreas

    2010-01-01

    This paper describes how relay interlocking systems as used by the Danish railways can be formally modelled and verified. Such systems are documented by circuit diagrams describing their static layout. It is explained how to derive a state transition system model for the dynamic behaviour...

  6. Relay Feedback Analysis for Double Integral Plants

    Directory of Open Access Journals (Sweden)

    Zhen Ye

    2011-01-01

    Full Text Available Double integral plants under relay feedback are studied. Complete results on the uniqueness of solutions, existence, and stability of the limit cycles are established using the point transformation method. Analytical expressions are also given for determining the amplitude and period of a limit cycle from the plant parameters.

  7. First Things First: Internet Relay Chat Openings.

    Science.gov (United States)

    Rintel, E. Sean; Mulholland, Joan; Pittam, Jeffery

    2001-01-01

    Argues that Internet Relay Chat (IRC) research needs to systematically address links between interaction structures, technological mediation and the instantiation and development of interpersonal relationships. Finds that openings that occur directly following user's entries into public IRC channels are often ambiguous, can disrupt relationship…

  8. Accurate outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. We first derive the exact statistics of received signal-to-noise (SNR) over each hop with co-located relays, in terms of probability density function (PDF). Then, the PDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

  9. Generator for X-ray diagnostics with mAs-relay

    International Nuclear Information System (INIS)

    Franke, K.

    1978-01-01

    The invention concerns a generator for X-ray diagnostics with mAs-relay, which is provided with organ keys for organ-programmed selection of mAs-products. For individual setting of the recording time the mAs-relay input is connected to an auxiliary source of current supplying a constant auxiliary current. The response barrier of the mAs-relay is thereby set by time set average. For overload protection may be used a power circuit which at exceeding the programmed times, e.g. the times provided for tomography operation, reduces the X-ray tube power step by step to allowed values by means of the X-ray tube current. (orig.) [de

  10. Accurate outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2011-04-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. We first derive the exact statistics of received signal-to-noise (SNR) over each hop with co-located relays, in terms of probability density function (PDF). Then, the PDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

  11. Achievable rate maximization for decode-and-forward MIMO-OFDM networks with an energy harvesting relay.

    Science.gov (United States)

    Du, Guanyao; Yu, Jianjun

    2016-01-01

    This paper investigates the system achievable rate for the multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system with an energy harvesting (EH) relay. Firstly we propose two protocols, time switching-based decode-and-forward relaying (TSDFR) and a flexible power splitting-based DF relaying (PSDFR) protocol by considering two practical receiver architectures, to enable the simultaneous information processing and energy harvesting at the relay. In PSDFR protocol, we introduce a temporal parameter to describe the time division pattern between the two phases which makes the protocol more flexible and general. In order to explore the system performance limit, we discuss the system achievable rate theoretically and formulate two optimization problems for the proposed protocols to maximize the system achievable rate. Since the problems are non-convex and difficult to solve, we first analyze them theoretically and get some explicit results, then design an augmented Lagrangian penalty function (ALPF) based algorithm for them. Numerical results are provided to validate the accuracy of our analytical results and the effectiveness of the proposed ALPF algorithm. It is shown that, PSDFR outperforms TSDFR to achieve higher achievable rate in such a MIMO-OFDM relaying system. Besides, we also investigate the impacts of the relay location, the number of antennas and the number of subcarriers on the system performance. Specifically, it is shown that, the relay position greatly affects the system performance of both protocols, and relatively worse achievable rate is achieved when the relay is placed in the middle of the source and the destination. This is different from the MIMO-OFDM DF relaying system without EH. Moreover, the optimal factor which indicates the time division pattern between the two phases in the PSDFR protocol is always above 0.8, which means that, the common division of the total transmission time into two equal phases in

  12. Selection, integration, and conflict monitoring; assessing the nature and generality of prefrontal cognitive control mechanisms.

    Science.gov (United States)

    Badre, David; Wagner, Anthony D

    2004-02-05

    Prefrontal cortex (PFC) supports flexible behavior by mediating cognitive control, though the elemental forms of control supported by PFC remain a central debate. Dorsolateral PFC (DLPFC) is thought to guide response selection under conditions of response conflict or, alternatively, may refresh recently active representations within working memory. Lateral frontopolar cortex (FPC) may also adjudicate response conflict, though others propose that FPC supports higher order control processes such as subgoaling and integration. Anterior cingulate cortex (ACC) is hypothesized to upregulate response selection by detecting response conflict; it remains unclear whether ACC functions generalize beyond monitoring response conflict. The present fMRI experiment directly tested these competing theories regarding the functional roles of DLPFC, FPC, and ACC. Results reveal dissociable control processes in PFC, with mid-DLPFC selectively mediating resolution of response conflict and FPC further mediating subgoaling/integration. ACC demonstrated a broad sensitivity to control demands, suggesting a generalized role in modulating cognitive control.

  13. Privacy-Preserving Evaluation of Generalization Error and Its Application to Model and Attribute Selection

    Science.gov (United States)

    Sakuma, Jun; Wright, Rebecca N.

    Privacy-preserving classification is the task of learning or training a classifier on the union of privately distributed datasets without sharing the datasets. The emphasis of existing studies in privacy-preserving classification has primarily been put on the design of privacy-preserving versions of particular data mining algorithms, However, in classification problems, preprocessing and postprocessing— such as model selection or attribute selection—play a prominent role in achieving higher classification accuracy. In this paper, we show generalization error of classifiers in privacy-preserving classification can be securely evaluated without sharing prediction results. Our main technical contribution is a new generalized Hamming distance protocol that is universally applicable to preprocessing and postprocessing of various privacy-preserving classification problems, such as model selection in support vector machine and attribute selection in naive Bayes classification.

  14. Feature Import Vector Machine: A General Classifier with Flexible Feature Selection.

    Science.gov (United States)

    Ghosh, Samiran; Wang, Yazhen

    2015-02-01

    The support vector machine (SVM) and other reproducing kernel Hilbert space (RKHS) based classifier systems are drawing much attention recently due to its robustness and generalization capability. General theme here is to construct classifiers based on the training data in a high dimensional space by using all available dimensions. The SVM achieves huge data compression by selecting only few observations which lie close to the boundary of the classifier function. However when the number of observations are not very large (small n ) but the number of dimensions/features are large (large p ), then it is not necessary that all available features are of equal importance in the classification context. Possible selection of an useful fraction of the available features may result in huge data compression. In this paper we propose an algorithmic approach by means of which such an optimal set of features could be selected. In short, we reverse the traditional sequential observation selection strategy of SVM to that of sequential feature selection. To achieve this we have modified the solution proposed by Zhu and Hastie (2005) in the context of import vector machine (IVM), to select an optimal sub-dimensional model to build the final classifier with sufficient accuracy.

  15. Iterative Relay Scheduling with Hybrid ARQ under Multiple User Equipment (Type II) Relay Environments

    KAUST Repository

    Nam, Sung Sik

    2018-01-09

    In this work, we propose an iterative relay scheduling with hybrid ARQ (IRS-HARQ) scheme which realizes fast jump-in/successive relaying and subframe-based decoding under the multiple user equipment (UE) relay environments applicable to the next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed IRS-HARQ aims to increase the achievable data rate by iteratively scheduling a relatively better UE relay closer to the end user in a probabilistic sense, provided that the relay-to-end user link should be operated in an open-loop and transparent mode. The latter is due to the fact that not only there are no dedicated control channels between the UE relay and the end user but also a new cell is not created. Under this open-loop and transparent mode, our proposed protocol is implemented by partially exploiting the channel state information based on the overhearing mechanism of ACK/NACK for HARQ. Further, the iterative scheduling enables UE-to-UE direct communication with proximity that offers spatial frequency reuse and energy saving.

  16. Relay Precoder Optimization in MIMO-Relay Networks With Imperfect CSI

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2011-11-01

    In this paper, we consider robust joint designs of relay precoder and destination receive filters in a nonregenerative multiple-input multiple-output (MIMO) relay network. The network consists of multiple source-destination node pairs assisted by a MIMO-relay node. The channel state information (CSI) available at the relay node is assumed to be imperfect. We consider robust designs for two models of CSI error. The first model is a stochastic error (SE) model, where the probability distribution of the CSI error is Gaussian. This model is applicable when the imperfect CSI is mainly due to errors in channel estimation. For this model, we propose robust minimum sum mean square error (SMSE), MSE-balancing, and relay transmit power minimizing precoder designs. The next model for the CSI error is a norm-bounded error (NBE) model, where the CSI error can be specified by an uncertainty set. This model is applicable when the CSI error is dominated by quantization errors. In this case, we adopt a worst-case design approach. For this model, we propose a robust precoder design that minimizes total relay transmit power under constraints on MSEs at the destination nodes. We show that the proposed robust design problems can be reformulated as convex optimization problems that can be solved efficiently using interior-point methods. We demonstrate the robust performance of the proposed design through simulations. © 2011 IEEE.

  17. Modeling the efficiency of Förster resonant energy transfer from energy relay dyes in dye-sensitized solar cells

    KAUST Repository

    Hoke, Eric T.

    2010-02-11

    Förster resonant energy transfer can improve the spectral breadth, absorption and energy conversion efficiency of dye sensitized solar cells. In this design, unattached relay dyes absorb the high energy photons and transfer the excitation to sensitizing dye molecules by Förster resonant energy transfer. We use an analytic theory to calculate the excitation transfer efficiency from the relay dye to the sensitizing dye accounting for dynamic quenching and relay dye diffusion. We present calculations for pores of cylindrical and spherical geometry and examine the effects of the Förster radius, the pore size, sensitizing dye surface concentration, collisional quenching rate, and relay dye lifetime. We find that the excitation transfer efficiency can easily exceed 90% for appropriately chosen dyes and propose two different strategies for selecting dyes to achieve record power conversion efficiencies. © 2010 Optical Society of America.

  18. Analyzing the impact of relay station characteristics on uplink performance in cellular network

    NARCIS (Netherlands)

    Dimitrova, D.C.; van den Berg, Hans Leo; Heijenk, Geert

    2009-01-01

    Uplink users in cellular networks, such as UMTS/ HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage. This paper focuses on the role of packet scheduling in cellular

  19. Using a micromachined magnetostatic relay in commutating a DC motor

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Wright, John A. (Inventor); Lilienthal, Gerald (Inventor)

    2004-01-01

    A DC motor is commutated by rotating a magnetic rotor to induce a magnetic field in at least one magnetostatic relay in the motor. Each relay is activated in response to the magnetic field to deliver power to at least one corresponding winding connected to the relay. In some cases, each relay delivers power first through a corresponding primary winding and then through a corresponding secondary winding to a common node. Specific examples include a four-pole, three-phase motor in which each relay is activated four times during one rotation of the magnetic rotor.

  20. Power allocation and cooperative jamming for enhancing physical layer security in opportunistic relay networks in the presence of interference

    KAUST Repository

    Abd El-Malek, Ahmed H.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, the impact of cochannel interference on the secrecy performance of dual-hop decode-and-forward relaying is investigated. In particular, the outage and intercept probabilities are obtained for the opportunistic relay selection (ORS) model in the presence of nonidentical interfering signals under a single/multiple passive eavesdropper(s) attack. Moreover, the proposed work enhances physical layer security performance of ORS model using cooperative jamming (CJ) techniques. Therefore, new closed-form expressions are derived for the intercept and outage probabilities of the CJ-ORS model in the presence of interference over Rayleigh fading channels. Moreover, the analyses are generalized to the case of multiple eavesdroppers where closed-form expressions are derived for the intercept probability. To reveal more insights on the proposed work secrecy performance, asymptotic closed-form expressions for the intercept and outage probabilities are obtained. Using these asymptotic expressions, a power allocation optimization problem is formulated and solved for enhancing the system security. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the paper. The results show that, although the cochannel interference increases the system outage probability, it might improve the system secrecy performance. Moreover, the proposed CJ-ORS model is shown to enhance the system secrecy performance compared to ORS model.

  1. Power allocation and cooperative jamming for enhancing physical layer security in opportunistic relay networks in the presence of interference

    KAUST Repository

    Abd El-Malek, Ahmed H.

    2017-04-18

    In this paper, the impact of cochannel interference on the secrecy performance of dual-hop decode-and-forward relaying is investigated. In particular, the outage and intercept probabilities are obtained for the opportunistic relay selection (ORS) model in the presence of nonidentical interfering signals under a single/multiple passive eavesdropper(s) attack. Moreover, the proposed work enhances physical layer security performance of ORS model using cooperative jamming (CJ) techniques. Therefore, new closed-form expressions are derived for the intercept and outage probabilities of the CJ-ORS model in the presence of interference over Rayleigh fading channels. Moreover, the analyses are generalized to the case of multiple eavesdroppers where closed-form expressions are derived for the intercept probability. To reveal more insights on the proposed work secrecy performance, asymptotic closed-form expressions for the intercept and outage probabilities are obtained. Using these asymptotic expressions, a power allocation optimization problem is formulated and solved for enhancing the system security. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the paper. The results show that, although the cochannel interference increases the system outage probability, it might improve the system secrecy performance. Moreover, the proposed CJ-ORS model is shown to enhance the system secrecy performance compared to ORS model.

  2. Switched diversity strategies for dual-hop amplify-and-forward relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-01-01

    This study investigates different receive single-branch switch-based diversity schemes for dual-hop amplify-and-forward relaying networks. Specifically, three receive processing algorithms are adopted, in which the receive branch is selected using the arbitrary selection algorithm, the switching algorithm, or the switching algorithm with post-examining best branch selection. The identification of the receive branch is carried out for two different system models. For the first model, a single-antenna relaying station is used in conjunction with a multiple-antenna transceiver, where the processing is performed independently of the first hop-fading conditions. The second model suggests the use of parallel deployment of single-antenna relays to transfer information from a multiple-antenna transmitter to a single-antenna receiver, where the active relaying station is determined based on the pre-combining end-to-end fading conditions. Performance comparisons for various transmission scenarios on the first hop are presented using new formulations for the statistics of the combined signal-to-noise ratio. Simulation results are also provided to validate the mathematical development and to verify the numerical computations. © 2012 The Institution of Engineering and Technology.

  3. Relay Architectures for 3GPP LTE-Advanced

    Directory of Open Access Journals (Sweden)

    Peters StevenW

    2009-01-01

    Full Text Available The Third Generation Partnership Project's Long Term Evolution-Advanced is considering relaying for cost-effective throughput enhancement and coverage extension. While analog repeaters have been used to enhance coverage in commercial cellular networks, the use of more sophisticated fixed relays is relatively new. The main challenge faced by relay deployments in cellular systems is overcoming the extra interference added by the presence of relays. Most prior work on relaying does not consider interference, however. This paper analyzes the performance of several emerging half-duplex relay strategies in interference-limited cellular systems: one-way, two-way, and shared relays. The performance of each strategy as a function of location, sectoring, and frequency reuse are compared with localized base station coordination. One-way relaying is shown to provide modest gains over single-hop cellular networks in some regimes. Shared relaying is shown to approach the gains of local base station coordination at reduced complexity, while two-way relaying further reduces complexity but only works well when the relay is close to the handset. Frequency reuse of one, where each sector uses the same spectrum, is shown to have the highest network throughput. Simulations with realistic channel models provide performance comparisons that reveal the importance of interference mitigation in multihop cellular networks.

  4. Criteria for selecting children with special needs for dental treatment under general anaesthesia

    OpenAIRE

    Nova García, M. Joaquín de; Gallardo López, Nuria E.; Martín Sanjuán, Carmen; Mourelle Martínez, M. Rosa; Alonso García, Yolanda; Carracedo Cabaleiro, Esther

    2007-01-01

    Objective: To study criteria for helping to select children with special needs for dental treatment under general anaesthesia. Materials and methods: Group of 30 children (aged under 18) examined on the Course at the Universidad Complutense de Madrid (UCM) (Specialisation on holistic dental treatment of children with special needs) and subsequently referred to the Disabled Children’s Oral Health Unit (DCOHU) within Primary Health Care Area 2 of the Madrid Health Service (SERMAS) where dental ...

  5. Selecting, training and assessing new general practice community teachers in UK medical schools.

    Science.gov (United States)

    Hydes, Ciaran; Ajjawi, Rola

    2015-09-01

    Standards for undergraduate medical education in the UK, published in Tomorrow's Doctors, include the criterion 'everyone involved in educating medical students will be appropriately selected, trained, supported and appraised'. To establish how new general practice (GP) community teachers of medical students are selected, initially trained and assessed by UK medical schools and establish the extent to which Tomorrow's Doctors standards are being met. A mixed-methods study with questionnaire data collected from 24 lead GPs at UK medical schools, 23 new GP teachers from two medical schools plus a semi-structured telephone interview with two GP leads. Quantitative data were analysed descriptively and qualitative data were analysed informed by framework analysis. GP teachers' selection is non-standardised. One hundred per cent of GP leads provide initial training courses for new GP teachers; 50% are mandatory. The content and length of courses varies. All GP leads use student feedback to assess teaching, but other required methods (peer review and patient feedback) are not universally used. To meet General Medical Council standards, medical schools need to include equality and diversity in initial training and use more than one method to assess new GP teachers. Wider debate about the selection, training and assessment of new GP teachers is needed to agree minimum standards.

  6. Mutual-Information-Based Incremental Relaying Communications for Wireless Biomedical Implant Systems

    Directory of Open Access Journals (Sweden)

    Yangzhe Liao

    2018-02-01

    Full Text Available Network lifetime maximization of wireless biomedical implant systems is one of the major research challenges of wireless body area networks (WBANs. In this paper, a mutual information (MI-based incremental relaying communication protocol is presented where several on-body relay nodes and one coordinator are attached to the clothes of a patient. Firstly, a comprehensive analysis of a system model is investigated in terms of channel path loss, energy consumption, and the outage probability from the network perspective. Secondly, only when the MI value becomes smaller than the predetermined threshold is data transmission allowed. The communication path selection can be either from the implanted sensor to the on-body relay then forwards to the coordinator or from the implanted sensor to the coordinator directly, depending on the communication distance. Moreover, mathematical models of quality of service (QoS metrics are derived along with the related subjective functions. The results show that the MI-based incremental relaying technique achieves better performance in comparison to our previous proposed protocol techniques regarding several selected performance metrics. The outcome of this paper can be applied to intra-body continuous physiological signal monitoring, artificial biofeedback-oriented WBANs, and telemedicine system design.

  7. Relaying Strategies and Protocols for Efficient Wireless Networks

    KAUST Repository

    Zafar, Ammar

    2014-10-01

    Next generation wireless networks are expected to provide high data rate and satisfy the Quality-of-Service (QoS) constraints of the users. A significant component of achieving these goals is to increase the effi ciency of wireless networks by either optimizing current architectures or exploring new technologies which achieve that. The latter includes revisiting technologies which were previously proposed, but due to a multitude of reasons were ignored at that time. One such technology is relaying which was initially proposed in the latter half of the 1960s and then was revived in the early 2000s. In this dissertation, we study relaying in conjunction with resource allocation to increase the effi ciency of wireless networks. In this regard, we differentiate between conventional relaying and relaying with buffers. Conventional relaying is traditional relaying where the relay forwards the signal it received immediately. On the other hand, in relaying with buffers or buffer-aided relaying as it is called, the relay can store received data in its buffer and forward it later on. This gives the benefit of taking advantage of good channel conditions as the relay can only transmit when the channel conditions are good. The dissertation starts with conventional relaying and considers the problem of minimizing the total consumed power while maintaining system QoS. After upper bounding the system performance, more practical algorithms which require reduced feedback overhead are explored. Buffer-aided relaying is then considered and the joint user-and-hop scheduler is introduced which exploits multi-user diversity (MUD) and 5 multi-hop diversity (MHD) gains together in dual-hop broadcast channels. Next joint user-and-hop scheduling is extended to the shared relay channel where two source-destination pairs share a single relay. The benefits of buffer-aided relaying in the bidirectional relay channel utilizing network coding are then explored. Finally, a new transmission protocol

  8. Adjustable electronic load-alarm relay

    International Nuclear Information System (INIS)

    Mason, C.H.; Sitton, R.S.

    1976-01-01

    An improved electronic alarm relay for monitoring the current drawn by an ac motor or other electrical load is described. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage. A circuit comprising a first resistor serially connected to a second resistor is connected across the outputs of the first and second amplifiers, and the junction of the two resistors is connected to the inverting terminal of the second amplifier. Means are provided to compare the aforementioned signal voltage with both the first and second reference voltages and to actuate an alarm if the signal voltage is higher than the first reference voltage or lower than the second reference voltage

  9. Exact Performance Analysis of Dual-Hop Semi-Blind AF Relaying over Arbitrary Nakagami-m Fading Channels

    KAUST Repository

    Xia, Minghua; Xing, Chengwen; Wu, Yik-Chung; Aissa, Sonia

    2011-01-01

    Relay transmission is promising for future wireless systems due to its significant cooperative diversity gain. The performance of dual-hop semi-blind amplify-and-forward (AF) relaying systems was extensively investigated, for transmissions over Rayleigh fading channels or Nakagami-𝑚 fading channels with integer fading parameter. For the general Nakagami-𝑚 fading with arbitrary 𝑚 values, the exact closed-form system performance analysis is more challenging. In this paper, we explicitly derive the moment generation function (MGF), probability density function (PDF) and moments of the end-to-end signal-to-noise ratio (SNR) over arbitrary Nakagami-𝑚 fading channels with semi-blind AF relay. With these results, the system performance evaluation in terms of outage probability, average symbol error probability, ergodic capacity and diversity order, is conducted. The analysis developed in this paper applies to any semi-blind AF relaying systems with fixed relay gain, and two major strategies for computing the relay gain are compared in terms of system performance. All analytical results are corroborated by simulation results and they are shown to be efficient tools to evaluate system performance.

  10. Exact Performance Analysis of Dual-Hop Semi-Blind AF Relaying over Arbitrary Nakagami-m Fading Channels

    KAUST Repository

    Xia, Minghua

    2011-10-01

    Relay transmission is promising for future wireless systems due to its significant cooperative diversity gain. The performance of dual-hop semi-blind amplify-and-forward (AF) relaying systems was extensively investigated, for transmissions over Rayleigh fading channels or Nakagami- fading channels with integer fading parameter. For the general Nakagami- fading with arbitrary values, the exact closed-form system performance analysis is more challenging. In this paper, we explicitly derive the moment generation function (MGF), probability density function (PDF) and moments of the end-to-end signal-to-noise ratio (SNR) over arbitrary Nakagami- fading channels with semi-blind AF relay. With these results, the system performance evaluation in terms of outage probability, average symbol error probability, ergodic capacity and diversity order, is conducted. The analysis developed in this paper applies to any semi-blind AF relaying systems with fixed relay gain, and two major strategies for computing the relay gain are compared in terms of system performance. All analytical results are corroborated by simulation results and they are shown to be efficient tools to evaluate system performance.

  11. Moments Based Framework for Performance Analysis of One-Way/Two-Way CSI-Assisted AF Relaying

    KAUST Repository

    Xia, Minghua

    2012-09-01

    When analyzing system performance of conventional one-way relaying or advanced two-way relaying, these two techniques are always dealt with separately and, thus, their performance cannot be compared efficiently. Moreover, for ease of mathematical tractability, channels considered in such studies are generally assumed to be subject to Rayleigh fading or to be Nakagami-$m$ channels with integer fading parameters, which is impractical in typical urban environments. In this paper, we propose a unified moments-based framework for general performance analysis of channel-state-information (CSI) assisted amplify-and-forward (AF) relaying systems. The framework is applicable to both one-way and two-way relaying over arbitrary Nakagami-$m$ fading channels, and it includes previously reported results as special cases. Specifically, the mathematical framework is firstly developed under the umbrella of the weighted harmonic mean of two Gamma-distributed variables in conjunction with the theory of Pad\\\\\\'e approximants. Then, general expressions for the received signal-to-noise ratios of the users in one-way/two-way relaying systems and the corresponding moments, moment generation function, and cumulative density function are established. Subsequently, the mathematical framework is applied to analyze, compare, and gain insights into system performance of one-way and two-way relaying techniques, in terms of outage probability, average symbol error probability, and achievable data rate. All analytical results are corroborated by simulation results as well as previously reported results whenever available, and they are shown to be efficient tools to evaluate and compare system performance of one-way and two-way relaying.

  12. Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF/FSO Relay Networks With Opportunistic User Scheduling

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2016-05-24

    In this paper, we study the performance of multiuser single-input multiple-output mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling. The considered system includes multiple users, one amplify-and-forward relay, one destination, and a multiple-antenna eavesdropper. The users are connected with the relay node through RF links and the relay is connected with the destination through an FSO link. Both maximum ratio combining and selection combining schemes are used at the multiple-antenna relay to combine the signal received from the best user on different antennas. The RF/FSO channels models are assumed to follow Nakagami-m/gamma-gamma fading models with pointing errors. Closed-form expressions are derived for the outage probability, average symbol error probability, and ergodic channel capacity. Then, the power of the selected best user is determined to minimize the system asymptotic outage probability under the dominant RF or FSO link. Then, the considered system secrecy performance is investigated, where the closed-form expressions for the intercept probability are derived. Finally, we propose a new cooperative jamming model in which the worst user is selected by the authorized system to jam the existing eavesdropper. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

  13. User Multiplexing in Relay Enhanced LTE-Advanced Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Frederiksen, Frank; Redana, Simone

    2010-01-01

    is radio relaying. This uses relay nodes that act as surrogate base stations for mobile users whose radio links with the base stations are not experiencing good enough conditions. In the downlink, the data that is destined for the relayed users may first have to be multiplexed by the base station, sent...... over the wireless backhaul link towards the relay node, and de-multiplexed and forwarded to the individual users by the relay node. The reverse process also has to be undertaken in the uplink. In this paper, we present a novel multiplexing scheme which is able to adapt the addressing and bitmapping...... of user identification to the actual number of users being served by the relay nodes, and thus greatly reduce the multiplexing overhead....

  14. A simple method for finding explicit analytic transition densities of diffusion processes with general diploid selection.

    Science.gov (United States)

    Song, Yun S; Steinrücken, Matthias

    2012-03-01

    The transition density function of the Wright-Fisher diffusion describes the evolution of population-wide allele frequencies over time. This function has important practical applications in population genetics, but finding an explicit formula under a general diploid selection model has remained a difficult open problem. In this article, we develop a new computational method to tackle this classic problem. Specifically, our method explicitly finds the eigenvalues and eigenfunctions of the diffusion generator associated with the Wright-Fisher diffusion with recurrent mutation and arbitrary diploid selection, thus allowing one to obtain an accurate spectral representation of the transition density function. Simplicity is one of the appealing features of our approach. Although our derivation involves somewhat advanced mathematical concepts, the resulting algorithm is quite simple and efficient, only involving standard linear algebra. Furthermore, unlike previous approaches based on perturbation, which is applicable only when the population-scaled selection coefficient is small, our method is nonperturbative and is valid for a broad range of parameter values. As a by-product of our work, we obtain the rate of convergence to the stationary distribution under mutation-selection balance.

  15. Order Selection for General Expression of Nonlinear Autoregressive Model Based on Multivariate Stepwise Regression

    Science.gov (United States)

    Shi, Jinfei; Zhu, Songqing; Chen, Ruwen

    2017-12-01

    An order selection method based on multiple stepwise regressions is proposed for General Expression of Nonlinear Autoregressive model which converts the model order problem into the variable selection of multiple linear regression equation. The partial autocorrelation function is adopted to define the linear term in GNAR model. The result is set as the initial model, and then the nonlinear terms are introduced gradually. Statistics are chosen to study the improvements of both the new introduced and originally existed variables for the model characteristics, which are adopted to determine the model variables to retain or eliminate. So the optimal model is obtained through data fitting effect measurement or significance test. The simulation and classic time-series data experiment results show that the method proposed is simple, reliable and can be applied to practical engineering.

  16. Variance-based selection may explain general mating patterns in social insects.

    Science.gov (United States)

    Rueppell, Olav; Johnson, Nels; Rychtár, Jan

    2008-06-23

    Female mating frequency is one of the key parameters of social insect evolution. Several hypotheses have been suggested to explain multiple mating and considerable empirical research has led to conflicting results. Building on several earlier analyses, we present a simple general model that links the number of queen matings to variance in colony performance and this variance to average colony fitness. The model predicts selection for multiple mating if the average colony succeeds in a focal task, and selection for single mating if the average colony fails, irrespective of the proximate mechanism that links genetic diversity to colony fitness. Empirical support comes from interspecific comparisons, e.g. between the bee genera Apis and Bombus, and from data on several ant species, but more comprehensive empirical tests are needed.

  17. A Generalized Measure for the Optimal Portfolio Selection Problem and its Explicit Solution

    Directory of Open Access Journals (Sweden)

    Zinoviy Landsman

    2018-03-01

    Full Text Available In this paper, we offer a novel class of utility functions applied to optimal portfolio selection. This class incorporates as special cases important measures such as the mean-variance, Sharpe ratio, mean-standard deviation and others. We provide an explicit solution to the problem of optimal portfolio selection based on this class. Furthermore, we show that each measure in this class generally reduces to the efficient frontier that coincides or belongs to the classical mean-variance efficient frontier. In addition, a condition is provided for the existence of the a one-to-one correspondence between the parameter of this class of utility functions and the trade-off parameter λ in the mean-variance utility function. This correspondence essentially provides insight into the choice of this parameter. We illustrate our results by taking a portfolio of stocks from National Association of Securities Dealers Automated Quotation (NASDAQ.

  18. Estimation and model selection of semiparametric multivariate survival functions under general censorship.

    Science.gov (United States)

    Chen, Xiaohong; Fan, Yanqin; Pouzo, Demian; Ying, Zhiliang

    2010-07-01

    We study estimation and model selection of semiparametric models of multivariate survival functions for censored data, which are characterized by possibly misspecified parametric copulas and nonparametric marginal survivals. We obtain the consistency and root- n asymptotic normality of a two-step copula estimator to the pseudo-true copula parameter value according to KLIC, and provide a simple consistent estimator of its asymptotic variance, allowing for a first-step nonparametric estimation of the marginal survivals. We establish the asymptotic distribution of the penalized pseudo-likelihood ratio statistic for comparing multiple semiparametric multivariate survival functions subject to copula misspecification and general censorship. An empirical application is provided.

  19. Cooperative AF Relaying in Spectrum-Sharing Systems: Performance Analysis under Average Interference Power Constraints and Nakagami-m Fading

    KAUST Repository

    Xia, Minghua

    2012-06-01

    Since the electromagnetic spectrum resource becomes more and more scarce, improving spectral efficiency is extremely important for the sustainable development of wireless communication systems and services. Integrating cooperative relaying techniques into spectrum-sharing cognitive radio systems sheds new light on higher spectral efficiency. In this paper, we analyze the end-to-end performance of cooperative amplify-and-forward (AF) relaying in spectrum-sharing systems. In order to achieve the optimal end-to-end performance, the transmit powers of the secondary source and the relays are optimized with respect to average interference power constraints at primary users and Nakagami-$m$ fading parameters of interference channels (for mathematical tractability, the desired channels from secondary source to relay and from relay to secondary destination are assumed to be subject to Rayleigh fading). Also, both partial and opportunistic relay-selection strategies are exploited to further enhance system performance. Based on the exact distribution functions of the end-to-end signal-to-noise ratio (SNR) obtained herein, the outage probability, average symbol error probability, diversity order, and ergodic capacity of the system under study are analytically investigated. Our results show that system performance is dominated by the resource constraints and it improves slowly with increasing average SNR. Furthermore, larger Nakagami-m fading parameter on interference channels deteriorates system performance slightly. On the other hand, when interference power constraints are stringent, opportunistic relay selection can be exploited to improve system performance significantly. All analytical results are corroborated by simulation results and they are shown to be efficient tools for exact evaluation of system performance.

  20. Energy-harvesting in cooperative AF relaying networks over log-normal fading channels

    KAUST Repository

    Rabie, Khaled M.; Salem, Abdelhamid; Alsusa, Emad; Alouini, Mohamed-Slim

    2016-01-01

    Energy-harvesting (EH) and wireless power transfer are increasingly becoming a promising source of power in future wireless networks and have recently attracted a considerable amount of research, particularly on cooperative two-hop relay networks in Rayleigh fading channels. In contrast, this paper investigates the performance of wireless power transfer based two-hop cooperative relaying systems in indoor channels characterized by log-normal fading. Specifically, two EH protocols are considered here, namely, time switching relaying (TSR) and power splitting relaying (PSR). Our findings include accurate analytical expressions for the ergodic capacity and ergodic outage probability for the two aforementioned protocols. Monte Carlo simulations are used throughout to confirm the accuracy of our analysis. The results show that increasing the channel variance will always provide better ergodic capacity performance. It is also shown that a good selection of the EH time in the TSR protocol, and the power splitting factor in the PTS protocol, is the key to achieve the best system performance. © 2016 IEEE.

  1. Energy-harvesting in cooperative AF relaying networks over log-normal fading channels

    KAUST Repository

    Rabie, Khaled M.

    2016-07-26

    Energy-harvesting (EH) and wireless power transfer are increasingly becoming a promising source of power in future wireless networks and have recently attracted a considerable amount of research, particularly on cooperative two-hop relay networks in Rayleigh fading channels. In contrast, this paper investigates the performance of wireless power transfer based two-hop cooperative relaying systems in indoor channels characterized by log-normal fading. Specifically, two EH protocols are considered here, namely, time switching relaying (TSR) and power splitting relaying (PSR). Our findings include accurate analytical expressions for the ergodic capacity and ergodic outage probability for the two aforementioned protocols. Monte Carlo simulations are used throughout to confirm the accuracy of our analysis. The results show that increasing the channel variance will always provide better ergodic capacity performance. It is also shown that a good selection of the EH time in the TSR protocol, and the power splitting factor in the PTS protocol, is the key to achieve the best system performance. © 2016 IEEE.

  2. Relay Telecommunications for the Coming Decade of Mars Exploration

    Science.gov (United States)

    Edwards, C.; DePaula, R.

    2010-01-01

    Over the past decade, an evolving network of relay-equipped orbiters has advanced our capabilities for Mars exploration. NASA's Mars Global Surveyor, 2001 Mars Odyssey, and Mars Reconnaissance Orbiter (MRO), as well as ESA's Mars Express Orbiter, have provided telecommunications relay services to the 2003 Mars Exploration Rovers, Spirit and Opportunity, and to the 2007 Phoenix Lander. Based on these successes, a roadmap for continued Mars relay services is in place for the coming decade. MRO and Odyssey will provide key relay support to the 2011 Mars Science Laboratory (MSL) mission, including capture of critical event telemetry during entry, descent, and landing, as well as support for command and telemetry during surface operations, utilizing new capabilities of the Electra relay payload on MRO and the Electra-Lite payload on MSL to allow significant increase in data return relative to earlier missions. Over the remainder of the decade a number of additional orbiter and lander missions are planned, representing new orbital relay service providers and new landed relay users. In this paper we will outline this Mars relay roadmap, quantifying relay performance over time, illustrating planned support scenarios, and identifying key challenges and technology infusion opportunities.

  3. Scalable DeNoise-and-Forward in Bidirectional Relay Networks

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Krigslund, Rasmus; Popovski, Petar

    2010-01-01

    In this paper a scalable relaying scheme is proposed based on an existing concept called DeNoise-and-Forward, DNF. We call it Scalable DNF, S-DNF, and it targets the scenario with multiple communication flows through a single common relay. The idea of the scheme is to combine packets at the relay...... in order to save transmissions. To ensure decodability at the end-nodes, a priori information about the content of the combined packets must be available. This is gathered during the initial transmissions to the relay. The trade-off between decodability and number of necessary transmissions is analysed...

  4. Amplify-and-forward relaying in wireless communications

    CERN Document Server

    Rodriguez, Leonardo Jimenez; Le-Ngoc, Tho

    2015-01-01

    This SpringerBrief explores the advantage of relaying techniques in addressing the increasing demand for high data rates and reliable services over the air. It demonstrates how to design cost-effective relay systems that provide high spectral efficiency and fully exploit the diversity of the relay channel. The brief covers advances in achievable rates, power allocation schemes, and error performance for half-duplex (HD) and full-duplex (FD) amplify-and-forward (AF) single-relay systems. The authors discuss the capacity and respective optimal power allocation for a wide range of HD protocols ov

  5. Modified Dynamic Decode-and-Forward Relaying Protocol for Type II Relay in LTE-Advanced and Beyond.

    Science.gov (United States)

    Nam, Sung Sik; Alouini, Mohamed-Slim; Choi, Seyeong

    2016-01-01

    In this paper, we propose a modified dynamic decode-and-forward (MoDDF) relaying protocol to meet the critical requirements for user equipment (UE) relays in next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed MoDDF realizes the fast jump-in relaying and the sequential decoding with an application of random codeset to encoding and re-encoding process at the source and the multiple UE relays, respectively. A subframe-by-subframe decoding based on the accumulated (or buffered) messages is employed to achieve energy, information, or mixed combining. Finally, possible early termination of decoding at the end user can lead to the higher spectral efficiency and more energy saving by reducing the frequency of redundant subframe transmission and decoding. These attractive features eliminate the need of directly exchanging control messages between multiple UE relays and the end user, which is an important prerequisite for the practical UE relay deployment.

  6. Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Du Bing

    2010-01-01

    Full Text Available A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC model, a common compact model in hierarchical wireless sensor networks (WSNs. The scheme uses Low-Density Parity-Check (LDPC as the surrogate to build up a layered structure which encapsulates the multiple constituent LDPC codes in the source and relay nodes. Specifically, the relay node decodes the messages from two sources, which are used to generate extra parity-check bits by a random network coding procedure to fill up the rate gap between Source-Relay and Source-Destination transmissions. Then, we derived the key algebraic relationships among multidimensional LDPC constituent codes as one of the constraints for code profile optimization. These extra check bits are sent to the destination to realize a cooperative diversity as well as to approach MARC decode-and-forward (DF capacity.

  7. Resource Allocation for the Multiband Relay Channel: A Building Block for Hybrid Wireless Networks

    Directory of Open Access Journals (Sweden)

    Kyounghwan Lee

    2010-01-01

    Full Text Available We investigate optimal resource allocation for the multiband relay channel. We find the optimal power and bandwidth allocation strategies that maximize the bounds on the capacity, by solving the corresponding max-min optimization problem. We provide sufficient conditions under which the associated max-min problem is equivalent to a supporting plane problem, which renders the solution for an arbitrary number of bands tractable. In addition, the sufficient conditions derived are general enough so that a class of utility functions can be accommodated with this formulation. As an example, we concentrate on the case where the source has two bands and the relay has a single band available and find the optimal resource allocation. We observe that joint power and bandwidth optimization always yields higher achievable rates than power optimization alone, establishing the merit of bandwidth sharing. Motivated by our analytical results, we examine a simple scenario where new channels become available for a transmitter to communicate; that is, new source to relay bands are added to a frequency division relay network. Given the channel conditions of the network, we establish the guidelines on how to allocate resources in order to achieve higher rates, depending on the relative quality of the available links.

  8. Economic selection index development for Beefmaster cattle II: General-purpose breeding objective.

    Science.gov (United States)

    Ochsner, K P; MacNeil, M D; Lewis, R M; Spangler, M L

    2017-05-01

    An economic selection index was developed for Beefmaster cattle in a general-purpose production system in which bulls are mated to a combination of heifers and mature cows, with resulting progeny retained as replacements or sold at weaning. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Genetic parameters were obtained from the literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits 1 at a time, by 1 unit, while holding the other traits constant at their respective means. Relative economic values for the objective traits calving difficultly direct (CDd), calving difficulty maternal (CDm), weaning weight direct (WWd), weaning weight maternal (WWm), mature cow weight (MW), and heifer pregnancy (HP) were -2.11, -1.53, 18.49, 11.28, -33.46, and 1.19, respectively. Consequently, under the scenario assumed herein, the greatest improvements in profitability could be made by decreasing maintenance energy costs associated with MW followed by improvements in weaning weight. The accuracy of the index lies between 0.218 (phenotypic-based index selection) and 0.428 (breeding values known without error). Implementation of this index would facilitate genetic improvement and increase profitability of Beefmaster cattle operations with a general-purpose breeding objective when replacement females are retained and with weaned calves as the sale end point.

  9. Multiple mini interview (MMI) for general practice training selection in Australia: interviewers' motivation.

    Science.gov (United States)

    Burgess, Annette; Roberts, Chris; Sureshkumar, Premala; Mossman, Karyn

    2018-01-25

    Multiple Mini Interviews (MMIs) are being used by a growing number of postgraduate training programs and medical schools as their interview process for selection entry. The Australian General Practice and Training (AGPT) used a National Assessment Centre (NAC) approach to selection into General Practice (GP) Training, which include MMIs. Interviewing is a resource intensive process, and implementation of the MMI requires a large number of interviewers, with a number of candidates being interviewed simultaneously. In 2015, 308 interviewers participated in the MMI process - a decrease from 340 interviewers in 2014, and 310 in 2013. At the same time, the number of applicants has steadily increased, with 1930 applications received in 2013; 2254 in 2014; and 2360 in 2015. This has raised concerns regarding the increasing recruitment needs, and the need to retain interviewers for subsequent years of MMIs. In order to investigate interviewers' reasons for participating in MMIs, we utilised self-determination theory (SDT) to consider interviewers' motivation to take part in MMIs at national selection centres. In 2015, 308 interviewers were recruited from 17 Regional Training Providers (RTPs) to participate in the MMI process at one of 15 NACs. For this study, a convenience sample of NAC sites was used. Forty interviewers were interviewed (n = 40; 40/308 = 13%) from five NACs. Framework analysis was used to code and categorise data into themes. Interviewers' motivation to take part as interviewers were largely related to their sense of duty, their desire to contribute their expertise to the process, and their desire to have input into selection of GP Registrars; a sense of duty to their profession; and an opportunity to meet with colleagues and future trainees. Interviewers also highlighted factors hindering motivation, which sometimes included the large number of candidates seen in one day. Interviewers' motivation for contributing to the MMIs was largely related

  10. Uplink Capacity of 802.16j Mobile Multihop Relay Networks with Transparent Relays

    DEFF Research Database (Denmark)

    Wang, Hua; Andrews, Jeffrey G.; Iversen, Villy Bæk

    2009-01-01

    -to-end spectral efficiency. Furthermore, the position and the number of relay stations (RSs) have a great impact on the capacity gain. These results are further verified in the evaluation of the system Erlang capacity. The study demonstrates that with proper deployment of RSs and use of MIMO transmission...

  11. Relay testing at Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Hofmayer, C.

    1989-01-01

    Brookhaven National Laboratory (BNL) is conducting a seismic test program on relays. The purpose of the test program is to investigate the influence of various designs, electrical and vibration parameters on the seismic capacity levels. The first series of testing has been completed and performed at Wyle Laboratories. The major part of the test program consisted of single axis, single frequency sine dwell tests. Random multiaxis, multifrequency tests were also performed. Highlights of the test results as well as a description of the testing methods are presented in this paper. 10 figs

  12. General quality of life of patients with acne vulgaris before and after performing selected cosmetological treatments

    Science.gov (United States)

    Chilicka, Karolina; Maj, Joanna; Panaszek, Bernard

    2017-01-01

    Background Achieving a satisfying quality of life for a patient by applying individually matched therapy is, simultaneously, a great challenge and a priority for contemporary medicine. Patients with visible dermatological ailments are particularly susceptible to reduction in the general quality of life. Among the dermatological diseases, acne causes considerable reduction in the quality of life and changes in self-perception that lead to the worsening of a patient’s mental condition, including depression and suicidal thoughts. As a result, difficulties in contact with loved ones, as well as social and professional problems are observed, which show that acne is not a somatic problem alone. To a large extent, it becomes a part of psychodermatology, becoming an important topic of public health in social medicine practice. Pharmacological treatment of acne is a challenge for a dermatologist and often requires the necessity of cooperating with a cosmetologist. Cosmetological treatments are aimed at improving the condition of the skin and reduction or subsiding of acne skin changes. Aim The aim of this study was to assess the influence of selected cosmetological treatments on the general quality of life of patients with acne. Materials and methods The study group consisted of 101 women aged 19–29 years (x¯=22.5 years, SD =2.3 years). All subjects were diagnosed with acne vulgaris of the face. In the study group, the acne changes occurred over the course of 3–15 years (x¯=8.1 years, SD =2.7 years). Selected cosmetological treatments (intensive pulsing light, alpha-hydroxy acids, cavitation peeling, needle-free mesotherapy, diamond microdermabrasion and sonophoresis) were performed in series in the number depending on the particular patient’s chosen treatment, after excluding contraindications. General quality of life of the patients was estimated using the Skindex-29 and Dermatology Life Quality Index (DLQI) questionnaires, before and after the cosmetological

  13. Postcolonial Sub-Saharan 1 State and Contemporary General Business Environment. Selected Issues

    Directory of Open Access Journals (Sweden)

    Tomasz W. Kolasinski

    2015-06-01

    Full Text Available Purpose: The paper presents the results of a qualitative analysis of selected aspects of general business environment. The author strives to answer the following question formulated in the context of postcolonial deliberations: has the general business environment been affected by European colonialism? Methodology: Semantic and semiotic analysis of primary sources (statistical data and research findings formulated by international organisations, such as the World Bank, OECD, UNIDO and secondary sources (scientific and research studies of Polish and foreign authors based on primary sources; literature review. Findings: In the postcolonial perspective, qualitative analysis shows neither a positive nor a negative impact of colonialism on the contemporary general business environment. If certain signs of its deterioration are observed, they are mostly due to the erosion of state capacity, whose origins can be traced back to the Berlin Conference. Originality: Papers on Postcolonial Management and Critical Management Studies (CMS bridge the gap in literaturę pertaining to management issues, especially in Poland. Due to their interdisciplinary nature, Postcolonial Management and CMS cover a broad range of research areas (i.e. theory of state and nation, sociology, economic history. They pertain to both economics an management, and are therefore difficult to classify.

  14. Performance of hybrid-ARQ with incremental redundancy over relay channels

    KAUST Repository

    Chelli, Ali; Alouini, Mohamed-Slim

    2012-01-01

    In this paper, we consider a relay network consisting of a source, a relay, and a destination. The source transmits a message to the destination using hybrid automatic repeat request (HARQ) with incremental redundancy (IR). The relay overhears

  15. A study of optimization problem for amplify-and-forward relaying over weibull fading channels

    KAUST Repository

    Ikki, Salama Said; Aissa, Sonia

    2010-01-01

    This paper addresses the power allocation and relay positioning problems in amplify-and-forward cooperative networks operating in Weibull fading environments. We study adaptive power allocation (PA) with fixed relay location, optimal relay location

  16. Outage Performance of Decode-and-Forward in Two-Way Relaying with Outdated CSI

    KAUST Repository

    Hyadi, Amal

    2015-01-07

    In this paper, we analyze the outage behavior of decode-and-forward relaying in the context of selective two-way cooperative systems. First, a new relay selection metric is proposed to take into consideration both transmission rates and instantaneous link conditions between cooperating nodes. Afterwards, the outage probability of the proposed system is derived for Nakagami-m fading channels in the case when perfect channel state information is available and then extended to the more realistic scenario where the available channel state information (CSI) is outdated due to fast fading. New expressions for the outage probability are obtained, and the impact of imperfect CSI on the performance is evaluated. Illustrative numerical results, Monte Carlo simulations, and comparisons with similar approaches are presented to assess the accuracy of our analytical derivations and confirm the performance gain of the proposed scheme.

  17. Two-Way Multiuser Mixed RF/FSO Relaying: Performance Analysis and Power Allocation

    KAUST Repository

    Al-Eryani, Yasser F.

    2018-03-21

    In this paper, the performance of two-way multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. RF links are used to conduct data transmission between users and relay node, while a FSO link is used to conduct data transmission on the last-mile communication link between the relay node and base station. The RF links are assumed to follow a Rayleigh fading model, while the FSO links are assumed to follow a unified Gamma-Gamma atmospheric turbulence fading model with pointing error. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ratio) outage probability, average symbol error rate, and average ergodic channel capacity are derived assuming a heterodyne detection scheme. The asymptotic results are used to conduct a power optimization algorithm where expressions for optimal transmission power values for the transmitting nodes are provided. Additionally, performance comparisons between the considered two-way-relaying (TWR) network and the oneway- relaying (OWR) network are provided and discussed. Also, the impact of several system parameters, including number of users, pointing errors, atmospheric turbulence conditions, and outage probability threshold on the overall network performance are investigated. All the theoretical results are validated by Monte Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of the OWR scheme with the same outage performance. Additionally, it is shown that under weak-to-moderate weather turbulence conditions and small pointing error, the outage probability is dominated by the RF downlink with a neglected effect for the user selection process at the RF uplink transmission. However, for severe pointing error, the outage probability is dominated by the FSO uplink/downlink transmission.

  18. An economically viable space power relay system

    Science.gov (United States)

    Bekey, Ivan; Boudreault, Richard

    1999-09-01

    This paper describes and analyzes the economics of a power relay system that takes advantage of recent technological advances to implement a system that is economically viable. A series of power relay systems are described and analyzed which transport power ranging from 1,250 megawatts to 5,000 megawatts, and distribute it to receiving sites at transcontinental distances. Two classes of systems are discussed—those with a single reflector and delivering all the power to a single rectenna, and a second type which has multiple reflectors and distributes it to 10 rectenna sites, sharing power among them. It is shown that when offering electricity at prices competitive to those prevalent in developed cities in the US that a low IRR is inevitable, and economic feasibility of a business is unlikely. However, when the target market is Japan where the prevalent electricity prices are much greater, that an IRR exceeding 65% is readily attainable. This is extremely attractive to potential investors, making capitalization of a venture likely. The paper shows that the capital investment required for the system can be less than 1 per installed watt, contributing less than 0.02 /KW-hr to the cost of energy provision. Since selling prices in feasible regions range from 0.18 to over 030 $/kW-hr, these costs are but a small fraction of the operating expenses. Thus a very large IRR is possible for such a business.

  19. CERN Relay Race: sporty and colourful

    CERN Multimedia

    Andy Butterworth, CERN Running Club

    2013-01-01

    On Thursday 23 May, the 43rd CERN Relay Race took place, with 108 teams on the starting line, the largest participation ever!       The DG was present at the start and said a few words to encourage the runners. At 12:15, the Solar Club and handbike racers, led by Jean-Yves Le Meur, were the first to set off. And as last year, the relay runners were accompanied by an enthusiastic group of Nordic walkers. The first team across the finish line was "Velo City", in a very fast time of 10'31". New this year was a prize category for the best fancy dress, which was won by Les Schtroumpfs from the BE Department. The challenge for the best represented department was won for the third year in a row by FP, but second and third were HR and IT, up from 6th and 9th places last year. To see all the pictures of the event, click here.

  20. Satellite-Relayed Intercontinental Quantum Network

    Science.gov (United States)

    Liao, Sheng-Kai; Cai, Wen-Qi; Handsteiner, Johannes; Liu, Bo; Yin, Juan; Zhang, Liang; Rauch, Dominik; Fink, Matthias; Ren, Ji-Gang; Liu, Wei-Yue; Li, Yang; Shen, Qi; Cao, Yuan; Li, Feng-Zhi; Wang, Jian-Feng; Huang, Yong-Mei; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Li, Li; Liu, Nai-Le; Koidl, Franz; Wang, Peiyuan; Chen, Yu-Ao; Wang, Xiang-Bin; Steindorfer, Michael; Kirchner, Georg; Lu, Chao-Yang; Shu, Rong; Ursin, Rupert; Scheidl, Thomas; Peng, Cheng-Zhi; Wang, Jian-Yu; Zeilinger, Anton; Pan, Jian-Wei

    2018-01-01

    We perform decoy-state quantum key distribution between a low-Earth-orbit satellite and multiple ground stations located in Xinglong, Nanshan, and Graz, which establish satellite-to-ground secure keys with ˜kHz rate per passage of the satellite Micius over a ground station. The satellite thus establishes a secure key between itself and, say, Xinglong, and another key between itself and, say, Graz. Then, upon request from the ground command, Micius acts as a trusted relay. It performs bitwise exclusive or operations between the two keys and relays the result to one of the ground stations. That way, a secret key is created between China and Europe at locations separated by 7600 km on Earth. These keys are then used for intercontinental quantum-secured communication. This was, on the one hand, the transmission of images in a one-time pad configuration from China to Austria as well as from Austria to China. Also, a video conference was performed between the Austrian Academy of Sciences and the Chinese Academy of Sciences, which also included a 280 km optical ground connection between Xinglong and Beijing. Our work clearly confirms the Micius satellite as a robust platform for quantum key distribution with different ground stations on Earth, and points towards an efficient solution for an ultralong-distance global quantum network.

  1. Satellite-Relayed Intercontinental Quantum Network.

    Science.gov (United States)

    Liao, Sheng-Kai; Cai, Wen-Qi; Handsteiner, Johannes; Liu, Bo; Yin, Juan; Zhang, Liang; Rauch, Dominik; Fink, Matthias; Ren, Ji-Gang; Liu, Wei-Yue; Li, Yang; Shen, Qi; Cao, Yuan; Li, Feng-Zhi; Wang, Jian-Feng; Huang, Yong-Mei; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Li, Li; Liu, Nai-Le; Koidl, Franz; Wang, Peiyuan; Chen, Yu-Ao; Wang, Xiang-Bin; Steindorfer, Michael; Kirchner, Georg; Lu, Chao-Yang; Shu, Rong; Ursin, Rupert; Scheidl, Thomas; Peng, Cheng-Zhi; Wang, Jian-Yu; Zeilinger, Anton; Pan, Jian-Wei

    2018-01-19

    We perform decoy-state quantum key distribution between a low-Earth-orbit satellite and multiple ground stations located in Xinglong, Nanshan, and Graz, which establish satellite-to-ground secure keys with ∼kHz rate per passage of the satellite Micius over a ground station. The satellite thus establishes a secure key between itself and, say, Xinglong, and another key between itself and, say, Graz. Then, upon request from the ground command, Micius acts as a trusted relay. It performs bitwise exclusive or operations between the two keys and relays the result to one of the ground stations. That way, a secret key is created between China and Europe at locations separated by 7600 km on Earth. These keys are then used for intercontinental quantum-secured communication. This was, on the one hand, the transmission of images in a one-time pad configuration from China to Austria as well as from Austria to China. Also, a video conference was performed between the Austrian Academy of Sciences and the Chinese Academy of Sciences, which also included a 280 km optical ground connection between Xinglong and Beijing. Our work clearly confirms the Micius satellite as a robust platform for quantum key distribution with different ground stations on Earth, and points towards an efficient solution for an ultralong-distance global quantum network.

  2. Record Participation in the Relay Race!

    CERN Multimedia

    2002-01-01

    CERN has a more sporting spirit than ever before. This is not the result of any survey, but the impression you got as soon as you saw the 62 teams of six runners each speeding around the laboratory in the 32nd annual relay race. This year 11 more teams competed than in 2001.   First changeover: Hervé Cornet takes over from Camille Ruiz Llamas for The Shabbys, and Sebastian Dorthe from Daniel Matteazzi for Charmilles Technologies. Jérôme Bendotti (EP/TA1) just holding off the team from the WHO at the finish. A total of 372 people ran together last Wednesday in this year's relay race, making for a record participation. It also seems that women are becoming more and more attracted by this competition, since this year there were eight ladies teams, also a new record. The first team were The Shabbys in a time of 10 minutes 45 seconds, finishing almost before the second team had started its last 300 metre leg. The 6 runners in each team cover distances of 1000, 800, 800,...

  3. Protective and control relays as coal-mine power-supply ACS subsystem

    Science.gov (United States)

    Kostin, V. N.; Minakova, T. E.

    2017-10-01

    The paper presents instantaneous selective short-circuit protection for the cabling of the underground part of a coal mine and central control algorithms as a Coal-Mine Power-Supply ACS Subsystem. In order to improve the reliability of electricity supply and reduce the mining equipment down-time, a dual channel relay protection and central control system is proposed as a subsystem of the coal-mine power-supply automated control system (PS ACS).

  4. Overview and Example Test Results of Modern Pilot Schemes for Coordination of Line Distance Protection Relays

    OpenAIRE

    Emil Bartosiewicz; Ryszard Kowalik; Marcin Januszewski

    2014-01-01

    The paper presents a short review of pilot schemes which are available in modern line distance protection relays, and example results of common pilot scheme tests with the testing methods description. Some differences in implementations of selected pilot schemes have been shown for comparison reasons. Distance protection coordination functions have been tested for GE Multilin UR series devices. Every type of available pilot scheme has been checked in synthetic tests and during the real ...

  5. 76 FR 58424 - Transmission Relay Loadability Reliability Standard

    Science.gov (United States)

    2011-09-21

    ... distribution providers to set load-responsive phase protection relays according to specific criteria to ensure...-part R.1.10 allows transmission owners, generation owners and distribution providers to set transformer.... Thus, requiring that transformer fault protection relays are set to not expose the transformer to a...

  6. Improper signaling in two-path relay channels

    KAUST Repository

    Gaafar, Mohamed

    2017-07-03

    Inter-relay interference (IRI) challenges the operation of two-path relaying systems. Furthermore, the unavailability of the channel state information (CSI) at the source and the limited detection capabilities at the relays prevent neither eliminating the interference nor adopting joint detection at the relays nodes. Improper signaling is a powerful signaling scheme that has the capability to reduce the interference impact at the receiver side and improves the achievable rate performance. Therefore, improper signaling is adopted at both relays, which have access to the global CSI. Then, improper signal characteristics are designed to maximize the total end-to-end achievable rate at the relays. To this end, both the power and the circularity coefficient, a measure of the impropriety degree of the signal, are optimized at the relays. Although the optimization problem is not convex, optimal power allocation for both relays for a fixed circularity coefficient is obtained. Moreover, the circularity coefficient is tuned to maximize the rate for a given power allocation. Finally, a joint solution of the optimization problem is proposed using a coordinate descent method based on alternate optimization. The simulation results show that employing improper signaling improves the achievable rate at medium and high IRI.

  7. 77 FR 16435 - Transmission Relay Loadability Reliability Standard

    Science.gov (United States)

    2012-03-21

    ... conditions on all applicable transmission lines and transformers. I. Background A. Relay Protection Systems 2... and a power swing. If a power swing is detected, the protection system, ``blocks,'' or prevents the... to the reliability of the Bulk-Power System by requiring load-responsive phase protection relay...

  8. Protective relaying of power systems using mathematical morphology

    CERN Document Server

    Wu, QH; Ji, TY

    2009-01-01

    Discusses the development of novel protective relaying algorithms, using Mathematical Morphology (MM). This book introduces the fundamental principles of MM, and brings together the applications of MM to develop different protective relaying algorithms for the protection of a variety of power system components.

  9. Resource allocation for relay assisted cognitive radio networks

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

    2012-01-01

    transmission power and the relay transmission power. Numerical results show that the optimal sensing time is dependent on the primary user's signal-to-noise-ratio (SNR). They also show that SCR increases with increase in the number of relays. © 2012 IEEE.

  10. 47 CFR 11.20 - State Relay Network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false State Relay Network. 11.20 Section 11.20... Network. This network is composed of State Relay (SR) sources, leased common carrier communications facilities or any other available communication facilities. The network distributes State EAS messages...

  11. Effects of Unified Power Flow Controller (UPFC) on Distance Relay ...

    African Journals Online (AJOL)

    This paper investigates the effects of UPFC on Distance Relay tripping characteristics in Nigerian 330kV (North-Central) Network. Its operation is based on impedance measurement at the relaying point. However, the system performance is often impeded by certain operational or structural factors such as load angle, the ...

  12. Cognitive Spectrum Efficient Multiple Access Technique using Relay Systems

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2007-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context will be presented and discussed in this paper. Ideas to increase the coverage of cellular systems by relay channels, relay stations and collaborate...

  13. Efficient Resource Scheduling by Exploiting Relay Cache for Cellular Networks

    Directory of Open Access Journals (Sweden)

    Chun He

    2015-01-01

    Full Text Available In relay-enhanced cellular systems, throughput of User Equipment (UE is constrained by the bottleneck of the two-hop link, backhaul link (or the first hop link, and access link (the second hop link. To maximize the throughput, resource allocation should be coordinated between these two hops. A common resource scheduling algorithm, Adaptive Distributed Proportional Fair, only ensures that the throughput of the first hop is greater than or equal to that of the second hop. But it cannot guarantee a good balance of the throughput and fairness between the two hops. In this paper, we propose a Two-Hop Balanced Distributed Scheduling (TBS algorithm by exploiting relay cache for non-real-time data traffic. The evolved Node Basestation (eNB adaptively adjusts the number of Resource Blocks (RBs allocated to the backhaul link and direct links based on the cache information of relays. Each relay allocates RBs for relay UEs based on the size of the relay UE’s Transport Block. We also design a relay UE’s ACK feedback mechanism to update the data at relay cache. Simulation results show that the proposed TBS can effectively improve resource utilization and achieve a good trade-off between system throughput and fairness by balancing the throughput of backhaul and access link.

  14. An automated thermoelectric power apparatus using electro-optic relays

    International Nuclear Information System (INIS)

    Chakravarti, A.; Ranganathan, R.

    1992-01-01

    We report the design and construction of a thermoelectric power apparatus using home-made electro-optic relays with Z-80A microprocessor for automatic data acquisition and control. The advantages of such relays made out of LED-LDR combinations for the measurement of ΔE and ΔT are discussed in details. (author). 7 refs., 5 figs

  15. Duplex Schemes in Multiple Antenna Two-Hop Relaying

    Directory of Open Access Journals (Sweden)

    Anja Klein

    2008-04-01

    Full Text Available A novel scheme for two-hop relaying defined as space division duplex (SDD relaying is proposed. In SDD relaying, multiple antenna beamforming techniques are applied at the intermediate relay station (RS in order to separate downlink and uplink signals of a bi-directional two-hop communication between two nodes, namely, S1 and S2. For conventional amplify-and-forward two-hop relaying, there appears a loss in spectral efficiency due to the fact that the RS cannot receive and transmit simultaneously on the same channel resource. In SDD relaying, this loss in spectral efficiency is circumvented by giving up the strict separation of downlink and uplink signals by either time division duplex or frequency division duplex. Two novel concepts for the derivation of the linear beamforming filters at the RS are proposed; they can be designed either by a three-step or a one-step concept. In SDD relaying, receive signals at S1 are interfered by transmit signals of S1, and receive signals at S2 are interfered by transmit signals of S2. An efficient method in order to combat this kind of interference is proposed in this paper. Furthermore, it is shown how the overall spectral efficiency of SDD relaying can be improved if the channels from S1 and S2 to the RS have different qualities.

  16. 77 FR 1039 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2012-01-09

    ... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 64 [WC Docket No. 10-191; Report No. 2939] Internet... toll-free numbers by users of Internet- based Telecommunications Relay Services (iTRS). DATES... any rules of particular applicability. Subject: Internet-Based Telecommunications Relay Service...

  17. Using the 5 P Relay in Task Groups

    Science.gov (United States)

    Stanley, Paula Helen

    2006-01-01

    This article describes the 5 P Relay, a group exercise that can increase the effectiveness of task groups. The 5 P Relay is based on the principles and concepts of the Invitational Model, which emphasizes the importance of assessing the effectiveness or health of five aspects of an organization's environment: people, places, programs, processes,…

  18. Improper signaling in two-path relay channels

    KAUST Repository

    Gaafar, Mohamed; Amin, Osama; Schaefer, Rafael F.; Alouini, Mohamed-Slim

    2017-01-01

    Inter-relay interference (IRI) challenges the operation of two-path relaying systems. Furthermore, the unavailability of the channel state information (CSI) at the source and the limited detection capabilities at the relays prevent neither eliminating the interference nor adopting joint detection at the relays nodes. Improper signaling is a powerful signaling scheme that has the capability to reduce the interference impact at the receiver side and improves the achievable rate performance. Therefore, improper signaling is adopted at both relays, which have access to the global CSI. Then, improper signal characteristics are designed to maximize the total end-to-end achievable rate at the relays. To this end, both the power and the circularity coefficient, a measure of the impropriety degree of the signal, are optimized at the relays. Although the optimization problem is not convex, optimal power allocation for both relays for a fixed circularity coefficient is obtained. Moreover, the circularity coefficient is tuned to maximize the rate for a given power allocation. Finally, a joint solution of the optimization problem is proposed using a coordinate descent method based on alternate optimization. The simulation results show that employing improper signaling improves the achievable rate at medium and high IRI.

  19. Protective Relay Studies for the Nigerian National Electric 330 KV ...

    African Journals Online (AJOL)

    The fundamental reasons for requiring these specific protective relaying features are also reviewed. Other protective relaying schemes that can accomplish the same basic protection objectives are presented. Based on the Nigerian special system characteristics, schemes to correct existing protection inadequacies are ...

  20. Relay Coordination in the Protection of Radially-Connected Power ...

    African Journals Online (AJOL)

    Protective relays detect intolerable or unwanted conditions within an assigned area, and then trip or open one or more circuit breakers to isolate the problem area before it can damage or otherwise interfere with the eective operation of the rest of the power system. It often happens that a substation feeder relay and ...

  1. Quasi-period oscillations of relay feedback systems

    International Nuclear Information System (INIS)

    Wen Guilin; Wang Qingguo; Lee, T.H.

    2007-01-01

    This paper presents an analytical method for investigation of the existence and stability of quasi-period oscillations (torus solutions) for a class of relay feedback systems. The idea is to analyze Poincare map from one switching surface to the next based on the Hopf bifurcation theory of maps. It is shown that there exist quasi-period oscillations in certain relay feedback systems

  2. Diagnostic imaging to select the candidates to orthotopic transplantation: Experience in a general hospital

    International Nuclear Information System (INIS)

    Pozzato, Carlo; Baldini, Umberto; Gattoni, Filippo; Raiteri, Riccardo; Lazzerini, Francesco; Uslenghi, Carlo Matteo; Mevoli, Alessandra

    1997-01-01

    The authors report the experience of our general hospital in selecting the patients for orthotopic liver transplantation (OLT). The accuracy of duplex Doppler and color flow Doppler for portal and/or mesenteric vein thrombosis was evaluated by correlation with resected livers, computerized tomography and angiographic findings. Pathologic examinations diagnosed HCC in 5/20 transplant recipients: 2 lesions were found in 2 resected specimens (total hepatectomy) and 1 lesion was found in 3 cases. The sensitivity of US, plain and dynamic computerized tomography in identifying HCC patients was 20%; US and computerized tomography specificity rates were 100% and 87%, respectively. CTAP sensitivity was 75% and the sensitivity of Lipiodol computerized tomography and angiography was 100%. Therefore, in our series, US was poorly sensitivity in the detection of liver cancers, which may depend on the small number of patients, lesion size and the radiologists ignoring clinical and laboratory data on purpose. Nevertheless, the patients with a single HCC not exceeding 5 cm in diameter or with no more than 3 tumors, none of them exceeding 3 cm in diameter, are generally considered eligible for transplantation: therefore, our patients chosen for OLT on the basis of US and computerized tomography findings were actually eligible for transplantation in spite of US and computerized tomography false negative results. In conclusion, considering also the long stand-by list for OLT, the first selection of transplant candidates could be performed with US and color flow Doppler, plain and dynamic computerized tomography. The patients who are not ruled out as candidates for OLT on the basis of the findings of these imaging techniques and of clinical and laboratory findings are submitted to no further examination and referred to the transplantation unit. Otherwise, if conventional and color flow Doppler US and conventional computerized tomography are not enough to exclude a patient from OLT, the

  3. Whether and Where to Code in the Wireless Relay Channel

    DEFF Research Database (Denmark)

    Shi, Xiaomeng; Médard, Muriel; Roetter, Daniel Enrique Lucani

    2013-01-01

    The throughput benefits of random linear network codes have been studied extensively for wirelined and wireless erasure networks. It is often assumed that all nodes within a network perform coding operations. In energy-constrained systems, however, coding subgraphs should be chosen to control...... the number of coding nodes while maintaining throughput. In this paper, we explore the strategic use of network coding in the wireless packet erasure relay channel according to both throughput and energy metrics. In the relay channel, a single source communicates to a single sink through the aid of a half......-duplex relay. The fluid flow model is used to describe the case where both the source and the relay are coding, and Markov chain models are proposed to describe packet evolution if only the source or only the relay is coding. In addition to transmission energy, we take into account coding and reception...

  4. Spectral efficiency enhancement with interference cancellation for wireless relay network

    DEFF Research Database (Denmark)

    Yomo, Hiroyuki; De Carvalho, Elisabeth

    The introduction of relaying into wireless communication system for coverage enhancement can cause severe decrease of spectral efficiency due to the requirement on extra radio resource. In this paper, we propose a method to increase spectral efficiency in such a wireless relay network by employing...... an interference cancellation technique. We focus on a typical scenario of relaying in a cellular system, where a mobile station (MS) requires the help of a relay station (RS) to communicate with the base station (BS). In such a case, interference cancellation can be used to achieve a small reuse distance...... of identical radio resource. We analyze a simple scenario with BS, single RS, and 2 MSs, and show that the proposed method has significant potential to enhance spectral efficiency in wireless relay networks....

  5. Effects of relay chatter in seismic probabilistic safety analysis

    International Nuclear Information System (INIS)

    Reed, J.W.; Shiu, K.K.

    1985-01-01

    In the Zion and Indian Point Probabilistic Safety Studies, relay chatter was dismissed as a credible event and hence was not formally included in the analyses. Although little discussion is given in the Zion and Indian Point PSA documentation concerning the basis for this decision, it has been expressed informally that it was assumed that the operators will be able to reset all relays in a timely manner. Currently, it is the opinion of many professionals that this may be an oversimplification. The three basic areas which must be considered in addressing relay chatter include the fragility of the relays per se, the reliability of the operators to reset the relays and finally the systems response aspects. Each of these areas is reviewed and the implications for seismic PSA are discussed. Finally, recommendations for future research are given

  6. An RSS based location estimation technique for cognitive relay networks

    KAUST Repository

    Qaraqe, Khalid A.

    2010-11-01

    In this paper, a received signal strength (RSS) based location estimation method is proposed for a cooperative wireless relay network where the relay is a cognitive radio. We propose a method for the considered cognitive relay network to determine the location of the source using the direct and the relayed signal at the destination. We derive the Cramer-Rao lower bound (CRLB) expressions separately for x and y coordinates of the location estimate. We analyze the effects of cognitive behaviour of the relay on the performance of the proposed method. We also discuss and quantify the reliability of the location estimate using the proposed technique if the source is not stationary. The overall performance of the proposed method is presented through simulations. ©2010 IEEE.

  7. A General Model of Negative Frequency Dependent Selection Explains Global Patterns of Human ABO Polymorphism.

    Directory of Open Access Journals (Sweden)

    Fernando A Villanea

    Full Text Available The ABO locus in humans is characterized by elevated heterozygosity and very similar allele frequencies among populations scattered across the globe. Using knowledge of ABO protein function, we generated a simple model of asymmetric negative frequency dependent selection and genetic drift to explain the maintenance of ABO polymorphism and its loss in human populations. In our models, regardless of the strength of selection, models with large effective population sizes result in ABO allele frequencies that closely match those observed in most continental populations. Populations must be moderately small to fall out of equilibrium and lose either the A or B allele (N(e ≤ 50 and much smaller (N(e ≤ 25 for the complete loss of diversity, which nearly always involved the fixation of the O allele. A pattern of low heterozygosity at the ABO locus where loss of polymorphism occurs in our model is consistent with small populations, such as Native American populations. This study provides a general evolutionary model to explain the observed global patterns of polymorphism at the ABO locus and the pattern of allele loss in small populations. Moreover, these results inform the range of population sizes associated with the recent human colonization of the Americas.

  8. Selected aspects of proposed new EU general data protection legal framework and the Croatian perspective

    Directory of Open Access Journals (Sweden)

    Nina GUMZEJ

    2013-12-01

    Full Text Available Proposed new EU general data protection legal framework profoundly affects a large number of day-to-day business operations of organizations processing personal data and calls for significant effort on their part toward the necessary legal-regulatory compliance. In this paper the author examines key legislative developments towards this new EU frame and impact for the Republic of Croatia as the youngest EU Member State. Following introductory overview, legal analysis of draft EU General Data Protection Regulation as proposed by the European Commission and recently adopted amendments by the European Parliament mainly focuses on selected solutions impacting national data protection supervisory authorities. This is complemented with examination of relevant sources of EU law, including the case law of the Court of Justice of the European Union. Assessment of results of this research is next made with respect to prospects of the data protection legal framework of the Republic of Croatia. The paper is concluded with the author’s critical overview of analyzed EU proposals impacting national data protection supervisory authorities in light of EU pivotal goals, and de lege ferenda proposals to timely address identified obstacles towards more adequate enforcement of data protection legislation in Croatia.

  9. Local dialogue and information within the frame of the setting up of relay antennas. Decreasing the exposure to electromagnetic waves emitted by mobile phone relay antennas. First phase report by Francois Brottes, chairman of the 'experimentations' COMOP

    International Nuclear Information System (INIS)

    Brottes, Francois

    2011-01-01

    The first part of this report describes the progress made on local dialogue and information within the frame of the setting up of relay antennas. It describes the implemented method with a selection of nine local communities, the main results of the dialogue (establishment of an information file, development of a tool set for the pilot communities, and operation, steering and assessment of experimentations). The second part describes the progress made on the exposure of population to electromagnetic waves emitted by mobile phone relay antennas (context, method, exposure status, simulation of the decreasing of relay antenna power, site experimentations). The third part proposes a set of recommendations related to local dialogue and information and to exposure

  10. Relay exchanges in elite short track speed skating.

    Science.gov (United States)

    Hext, Andrew; Heller, Ben; Kelley, John; Goodwill, Simon

    2017-06-01

    In short track speed skating, the relay exchange provides an additional strategic component to races by allowing a team to change the skater involved in the pack race. Typically executed every 1½ laps, it is the belief of skaters and coaches that during this period of the race, time can be gained or lost due to the execution of the relay exchange. As such, the aim of this study was to examine the influence of the relay exchange on a team's progression through a 5000 m relay race. Using data collected from three World Cup relay events during the 2012-2013 season, the time taken to complete the straight for the scenarios with and without the relay exchange were compared at different skating speeds for the corner exit prior to the straight. Overall, the influence of the relay exchange was found to be dependent on this corner exit speed. At slower corner exit speeds (12.01-13.5 m/s), relay exchange straight times were significantly faster than the free skating scenario (P < 0.01). While at faster corner exit speeds (14.01-15 m/s), straight times were significantly slower (P < 0.001). The findings of this study suggest that the current norm of executing relay exchanges every 1½ laps may not be optimal. Instead, varying the frequency of relay exchange execution throughout the race could allow: (1) time to be gained relative to other teams; and (2) facilitate other race strategies by providing an improved opportunity to overtake.

  11. The fuzzy TOPSIS and generalized Choquet fuzzy integral algorithm for nuclear power plant site selection - a case study from Turkey

    International Nuclear Information System (INIS)

    Kurt, Ünal

    2014-01-01

    The location selection for nuclear power plant (NPP) is a strategic decision, which has significant impact on the economic operation of the plant and sustainable development of the region. This paper proposes fuzzy TOPSIS and generalized Choquet fuzzy integral algorithm for evaluation and selection of optimal locations for NPP in Turkey. Many sub-criteria such as geological, social, touristic, transportation abilities, cooling water capacity and nearest to consumptions markets are taken into account. Among the evaluated locations, according to generalized Choquet fuzzy integral method, Inceburun–Sinop was selected as a study site due to its highest performance and meeting most of the investigated criteria. The Inceburun-Sinop is selected by generalized Choquet fuzzy integral and fuzzy TOPSIS Iğneada–Kırklareli took place in the first turn. The Mersin–Akkuyu is not selected in both methods. (author)

  12. Enhancing the efficiency of constrained dual-hop variable-gain AF relaying under nakagami-m fading

    KAUST Repository

    Zafar, Ammar

    2014-07-01

    This paper studies power allocation for performance constrained dual-hop variable-gain amplify-and-forward (AF) relay networks in Nakagami- $m$ fading. In this context, the performance constraint is formulated as a constraint on the end-to-end signal-to-noise-ratio (SNR) and the overall power consumed is minimized while maintaining this constraint. This problem is considered under two different assumptions of the available channel state information (CSI) at the relays, namely full CSI at the relays and partial CSI at the relays. In addition to the power minimization problem, we also consider the end-to-end SNR maximization problem under a total power constraint for the partial CSI case. We provide closed-form solutions for all the problems which are easy to implement except in two cases, namely selective relaying with partial CSI for power minimization and SNR maximization, where we give the solution in the form of a one-variable equation which can be solved efficiently. Numerical results are then provided to characterize the performance of the proposed power allocation algorithms considering the effects of channel parameters and CSI availability. © 2014 IEEE.

  13. General quality of life of patients with acne vulgaris before and after performing selected cosmetological treatments

    Directory of Open Access Journals (Sweden)

    Chilicka K

    2017-08-01

    Full Text Available Karolina Chilicka,1 Joanna Maj,2 Bernard Panaszek3 1Department of Cosmetology, Opole Medical School, Opole, 2Department of Dermatology, Venereology and Allergology, 3Department of Internal Medicine and Allergy, Wroclaw Medical University, Wrocław, Poland Background: Achieving a satisfying quality of life for a patient by applying individually matched therapy is, simultaneously, a great challenge and a priority for contemporary medicine. Patients with visible dermatological ailments are particularly susceptible to reduction in the general quality of life. Among the dermatological diseases, acne causes considerable reduction in the quality of life and changes in self-perception that lead to the worsening of a patient’s mental condition, including depression and suicidal thoughts. As a result, difficulties in contact with loved ones, as well as social and professional problems are observed, which show that acne is not a somatic problem alone. To a large extent, it becomes a part of psychodermatology, becoming an important topic of public health in social medicine practice. Pharmacological treatment of acne is a challenge for a dermatologist and often requires the necessity of cooperating with a cosmetologist. Cosmetological treatments are aimed at improving the condition of the skin and reduction or subsiding of acne skin changes.Aim: The aim of this study was to assess the influence of selected cosmetological treatments on the general quality of life of patients with acne.Materials and methods: The study group consisted of 101 women aged 19–29 years (x̅  =22.5 years, SD =2.3 years. All subjects were diagnosed with acne vulgaris of the face. In the study group, the acne changes occurred over the course of 3–15 years (x̅ =8.1 years, SD =2.7 years. Selected cosmetological treatments (intensive pulsing light, alpha-hydroxy acids, cavitation peeling, needle-free mesotherapy, diamond microdermabrasion and sonophoresis were performed in

  14. Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

    Directory of Open Access Journals (Sweden)

    Buha Danilo

    2016-01-01

    Full Text Available The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B" are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according to which the calculations are done are described. Criteria used to provide the protection to fulfill the backup protection role in the event of malfunction of the main protection of the transmission system. are clarified. The calculation of all protection functions (32 functions of generator B1 were performed in the project "Coordination of relay protection blocks B1 and B2 with the system of excitation and power system protections -TENT B".

  15. Semiconductor relay and its manufacture method. Handotai relay oyobi sono seizo hoho

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, M

    1993-06-01

    The invention relates to a semiconductor relay in which a light emitting diode and a photovoltaic element are arranged in the opposite positions and connected with a light connection and aims to present a light transmission path to transmit input signals to the light emitting diode to the side of the photovoltaic element with a negligible light loss effectively. The invention presents a semiconductor relay, in which a light emitting diode loaded on the first lead frame and the light receiving part of the photovoltaic element to drive a MOSFET element loaded on the second lead frame and acting as a switch element are connected through an insulator tube with an opaque outer wall, and the interior of the insulator tube is filled with a transparent insulating filler, so that the invention affords a light transmission path without light leakage from the interior of the opaque insulator tube and with the stability in the form and no light loss. 3 figs.

  16. Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

    OpenAIRE

    Buha Danilo; Buha Boško; Jačić Dušan; Gligorov Saša; Božilov Marko; Marinković Savo; Milosavljević Srđan

    2016-01-01

    The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B") are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according ...

  17. CERN Relay Race | 5 June | Get ready!

    CERN Multimedia

    CERN Medical Service

    2014-01-01

    In anticipation of the CERN relay race, the Medical Service would like to remind all participants that preparing for this sporting activity is essential - even though it is a short event.   Progressive and regular training. Adequate nutrition and hydration. Advice and information is available at the infirmary in Building 57. Everyone should adapt their physical activity to match their fitness levels, bearing in mind that the aim of this race is not necessarily to achieve great success but to participate in a collective sporting event. In the framework of the "Move! Eat better" campaign and for the third successive year, a 2.4 km route is open to walkers, both beginners and experts. Before, during and after this event, test yourself with a pedometer, available from the CERN infirmary! 

  18. Testing of high-impedance fault relays

    Energy Technology Data Exchange (ETDEWEB)

    Nagpal, M. [Powertech Labs., Inc., Surrey, BC (Canada)

    1995-11-01

    A test system and protocol was developed for the testing of high-impedance fault (HIF) detection devices. A technique was established for point-by-point addition of fault and load currents, the resultant was used for testing the performance of the devices in detecting HIFs in the presence of load current. The system used digitized data from recorded faults and normal currents to generate analog test signals for high-impedance fault detection relays. A test apparatus was built with a 10 kHz band-width and playback duration of 30 minutes on 6 output channels for testing purposes. Three devices which have recently become available were tested and their performance was evaluated based on their respective test results.

  19. Large Efficient Intelligent Heating Relay Station System

    Science.gov (United States)

    Wu, C. Z.; Wei, X. G.; Wu, M. Q.

    2017-12-01

    The design of large efficient intelligent heating relay station system aims at the improvement of the existing heating system in our country, such as low heating efficiency, waste of energy and serious pollution, and the control still depends on the artificial problem. In this design, we first improve the existing plate heat exchanger. Secondly, the ATM89C51 is used to control the whole system and realize the intelligent control. The detection part is using the PT100 temperature sensor, pressure sensor, turbine flowmeter, heating temperature, detection of user end liquid flow, hydraulic, and real-time feedback, feedback signal to the microcontroller through the heating for users to adjust, realize the whole system more efficient, intelligent and energy-saving.

  20. A novel framework on exact average symbol error probabilities of multihop transmission over amplify-and-forward relay fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2010-09-01

    In this paper, we propose an analytical framework on the exact computation of the average symbol error probabilities (ASEP) of multihop transmission over generalized fading channels when an arbitrary number of amplify-and-forward relays is used. Our approach relies on moment generating function (MGF) framework to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are a convenient tool to analyze the ASEP performance of multihop transmission over amplify-and-forward relay fading channels. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement. © 2010 IEEE.

  1. A novel framework on exact average symbol error probabilities of multihop transmission over amplify-and-forward relay fading channels

    KAUST Repository

    Yilmaz, Ferkan; Kucur, Oǧuz; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, we propose an analytical framework on the exact computation of the average symbol error probabilities (ASEP) of multihop transmission over generalized fading channels when an arbitrary number of amplify-and-forward relays is used. Our approach relies on moment generating function (MGF) framework to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are a convenient tool to analyze the ASEP performance of multihop transmission over amplify-and-forward relay fading channels. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement. © 2010 IEEE.

  2. Mobility Impact on Centralized Selection of Mobile Relays

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2010-01-01

    parameters on the achieved average BER of data transmissions. The SNR measurement collection is based on periodic hello broadcasts. Results show that increasing node speed can lead to performance that is worse than always transmitting directly. The hello broadcast rate can mitigate this effect, however......, at the cost of an increase in signaling overhead. We find that discarding old measurements can significantly improve the BER performance without increasing the signaling overhead. This result establishes the importance of joint tuning of the hello broadcast rate and the measurement storage time....

  3. David Hull's generalized natural selection as an explanation for scientific change

    Science.gov (United States)

    Little, Michelle Yvette

    2001-10-01

    Philosophers of science such as Karl Popper and Thomas Kuhn have employed evolutionary idiom in describing scientific change. In Science as a Process (1988) Hull makes evolutionary theory explanatorily applicable. He modifies key evolutionary terms in order that both biological evolution and scientific change are instances of a general selection process. According to Hull, because of naturally-existing competition for credit among researchers and the professional lineages they constitute, scientists are constrained to cooperate and collaborate. This process entails two important philosophical consequences. First, it allows for a natural justification of why the sciences can provide objective empirical knowledge. Second, appreciating its strength means that a philosophical analysis of scientific change is solidly difficult features to combine. I work on strengthening two weaknesses in Hull's arguments. First, operating in his analysis is an unexplicated notion of ``information'' running parallel to the equally opaque notion of genetic information. My third chapter provides a clear account of ``genetic information'' whose usefulness extends beyond the assistance it can render Hull as a clear concept is needed in biological contexts as well. The fourth and fifth chapters submit evidence of scientific change from radio astronomy. Hull insists on empirical backing for philosophical theses but his own book stands to suffer from selection effects as it offers cases drawn from a single subspecialty in the biological sciences. I found that in the main scientists and the change they propel accords well with Hull's explanation. However, instances of major change reveal credit- and resource-sharing to a degree contrary with what Hull would expect. My conclusion is that the naturalness of competition, instantiated during the course of standardized and relatively ``normal'' scientific research, is not the norm during periods of new research and its uncertain standards of

  4. [General principles of effective communication between physician and patient with selected mental disorders].

    Science.gov (United States)

    Błaszczyk, Justyna; Bobińska, Kinga; Filip, Maria; Gałecki, Piotr

    2015-04-01

    Faced with the growing frequency of mental disorders occurrence and considering the necessity of improving the patient care, it is particularly important that physicians of different specialties knew the general principles of effective communication with patients who are mentally ill. Equally important is to spread the knowledge of the symptomatology of various mental illnesses. Studies published by the Institute of Psychiatry and Neurology involving persons between 18 and 64 years old, show that 8 millions Poles suffers or suffered from mental disorders. This represents almost 25% of Polish society. The above data confirm, that basic knowledge of criteria for diagnosing mental disorders and their treatment by primary care physicians, determines the success of the entire health care system. It must be taken into consideration that frequently patients seeing general practitioner (GP) are suffering from more than one mental illness or it is accompanied by somatic disease. Adequate communication determines effective treatment. Simple yet exact message, ability to adapt it to patient and problems reported by him, is a valuable means in daily medical practice. It reduces the risk of iatrogenic disorder, encourages the efficiency of the entire therapeutic process. Good cooperation with the patient is also determined by patience, empathy, understanding, and competence. The aim of this study is to present the principles of effective communication between doctor and patient suffering from selected mental disorders. The article defines the concept of communication. It shows symptomatology of primary psychiatric disorders. Moreover, the most common difficulties in relationship between the doctor and the patient had been pointed. © 2015 MEDPRESS.

  5. Distance relay performance in future converter dominated power systems

    DEFF Research Database (Denmark)

    Sarkar, Moumita; Jia, Jundi; Yang, Guangya

    2017-01-01

    Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up ...... of converter controls on fault current response of converter-based generations is also investigated. Index Terms—Converter control, distance relays, power system protection, system modelling....... to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of converter dominated systems on performance of distance relays. Backup functionality of the distance...... relay is major concern as miscoordination of backup relays in case of cascading faults can lead to severe stress in system, which can develop into blackout. In this paper, response of relays in traditional system is compared with response of relays in low short-circuit-current power systems. Impact...

  6. Mobile User Connectivity in Relay-Assisted Visible Light Communications

    Directory of Open Access Journals (Sweden)

    Petr Pešek

    2018-04-01

    Full Text Available In this paper, we investigate relay-assisted visible light communications (VLC where a mobile user acts as a relay and forwards data from a transmitter to the end mobile user. We analyse the utilization of the amplify-and-forward (AF and decode-and-forward (DF relaying schemes. The focus of the paper is on analysis of the behavior of the mobile user acting as a relay while considering a realistic locations of the receivers and transmitters on a standard mobile phone, more specifically with two photodetectors on both sides of a mobile phone and a transmitting LED array located upright. We also investigate dependency of the bit error rate (BER performance on the azimuth and elevation angles of the mobile relay device within a typical office environment. We provide a new analytical description of BER for AF and DF-based relays in VLC. In addition we compare AF and DF-based systems and show that DF offers a marginal improvement in the coverage area with a BER < 10–3 and a data rate of 100 Mb/s. Numerical results also illustrate that relay-based systems offer a significant improvement in terms of the coverage compared to direct non-line of sight VLC links.

  7. Distributed stability control using intelligent voltage-margin relay

    Energy Technology Data Exchange (ETDEWEB)

    Wiszniewski, A.; Rebizant, W. [Wroclaw Univ. of Technology (Poland); Klimek, A. [Powertech Labs Inc., Surrey, BC (Canada)

    2010-07-01

    This paper presented an intelligent relay that operates if the load to source impedance ratio decreases to a level that is dangerously close to the stability limit, which leads to power system blackouts. The intelligent voltage-margin/difference relay installed at receiving substations automatically initiates action if the voltage stability margin drops to a dangerously low level. The relay decides if the tap changing devices are to be blocked and if under-voltage load shedding should be initiated, thereby mitigating an evolving instability. The intelligent relay has two levels of operation. At the first stage, which corresponds to the higher load to source impedance ratio, the relay initiates blocking of the tap changer. At the second stage, corresponding to the lower source to load impedance ratio, load shedding is initiated. The relay operates when the load to source impedance ratio reaches a certain predetermined level, but it does not depend either on the level of the source voltage or on the difference of source and load impedance phase angles. The algorithm for the relay is relatively simple and uses only locally available signals. Consequently, the transformer is well controlled to eliminate the cases of voltage instability. 6 refs., 7 figs.

  8. Admission Control Threshold in Cellular Relay Networks with Power Adjustment

    Directory of Open Access Journals (Sweden)

    Lee Ki-Dong

    2009-01-01

    Full Text Available Abstract In the cellular network with relays, the mobile station can benefit from both coverage extension and capacity enhancement. However, the operation complexity increases as the number of relays grows up. Furthermore, in the cellular network with cooperative relays, it is even more complex because of an increased dimension of signal-to-noise ratios (SNRs formed in the cooperative wireless transmission links. In this paper, we propose a new method for admission capacity planning in a cellular network using a cooperative relaying mechanism called decode-and-forward. We mathematically formulate the dropping ratio using the randomness of "channel gain." With this, we formulate an admission threshold planning problem as a simple optimization problem, where we maximize the accommodation capacity (in number of connections subject to two types of constraints. (1 A constraint that the sum of the transmit powers of the source node and relay node is upper-bounded where both nodes can jointly adjust the transmit power. (2 A constraint that the dropping ratio is upper-bounded by a certain threshold value. The simplicity of the problem formulation facilitates its solution in real-time. We believe that the proposed planning method can provide an attractive guideline for dimensioning a cellular relay network with cooperative relays.

  9. Two-Hop Secure Communication Using an Untrusted Relay

    Directory of Open Access Journals (Sweden)

    Xiang He

    2009-01-01

    Full Text Available We consider a source-destination pair that can only communicate through an untrusted intermediate relay node. The intermediate node is willing to employ a designated relaying scheme to facilitate reliable communication between the source and the destination. Yet, the information it relays needs to be kept secret from it. In this two-hop communication scenario, where the use of the untrusted relay node is essential, we find that a positive secrecy rate is achievable. The center piece of the achievability scheme is the help provided by either the destination node with transmission capability, or an external “good samaritan” node. In either case, the helper performs cooperative jamming that confuses the eavesdropping relay and disables it from being able to decipher what it is relaying. We next derive an upper bound on the secrecy rate for this system. We observe that the gap between the upper bound and the achievable rate vanishes as the power of the relay node goes to infinity. Overall, the paper presents a case for intentional interference, that is, cooperative jamming, as an enabler for secure communication.

  10. Children's and parent's psychological profiles in selective mutism and generalized anxiety disorder: a clinical study.

    Science.gov (United States)

    Capozzi, Flavia; Manti, Filippo; Di Trani, Michela; Romani, Maria; Vigliante, Miriam; Sogos, Carla

    2017-10-28

    Selective mutism (SM) is classified in DSM-5 as an anxiety disorder. The aim of the study was to investigate the psychological features of children with SM and their parental psychological profiles, compared to generalized anxiety disorder (GAD) children and their parents. The parents of 26 preschool children with SM and 32 with children with GAD filled out the child behavior check list for 1½-5 years (CBCL1½-5) and the symptom checklist-90-revised (SCL-90-R). Information about the children and their parents' histories was collected through clinical interviews. Children with SM scored higher than children with GAD on the CBCL1½-5 withdrawn scale and lower on the attention problems, aggressive behavior, and externalizing problems scales. Mothers of children with SM scored higher on the SCL-90-R obsessive-compulsive subscale and Global Severity Index than mothers of children with GAD, while fathers of children with SM scored higher on the SCL-90-R Phobic Anxiety subscale and on the Global Severity Index than fathers of children with GAD. Parents of children with SM displayed a greater presence of stressful life events than parents of children with GAD. Data appeared to confirm that SM and GAD share a common anxious core, though some differences in the children's psychological profiles and the parents' history and personality emerged. Future research should focus on the role of external factors, such as parent-child relationship, in the development of SM.

  11. Exact capacity analysis of multihop transmission over amplify-and-forward relay fading channels

    KAUST Repository

    Yilmaz, Ferkan; Kucur, Oǧuz; Alouini, Mohamed-Slim

    2010-01-01

    In this paper, we propose an analytical framework on the exact computation of the average capacity of multihop transmission over amplify-and-forward relay fading channels. Our approach relies on the algebraic combination of Mellin and Laplace transforms to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are a convenient tool to analyze the average capacity of multihop transmission over amplify-and-forward relay fading channels. As an application of the analytical framework on the exact computation of the average capacity of multihop transmission, some examples are accentuated for generalized Nakagami-m fading channels. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement. ©2010 IEEE.

  12. Exact capacity analysis of multihop transmission over amplify-and-forward relay fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2010-09-01

    In this paper, we propose an analytical framework on the exact computation of the average capacity of multihop transmission over amplify-and-forward relay fading channels. Our approach relies on the algebraic combination of Mellin and Laplace transforms to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are a convenient tool to analyze the average capacity of multihop transmission over amplify-and-forward relay fading channels. As an application of the analytical framework on the exact computation of the average capacity of multihop transmission, some examples are accentuated for generalized Nakagami-m fading channels. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement. ©2010 IEEE.

  13. Multistability and hidden attractors in a relay system with hysteresis

    DEFF Research Database (Denmark)

    Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Rubanov, Vasily G.

    2015-01-01

    with the neighborhood of that cycle. We show how the equilibrium point of a relay system disappears in a boundary-equilibrium bifurcation as the system enters the region of autonomous switching dynamics and demonstrate experimentally how a relay system can exhibit large amplitude chaotic oscillations at high values...... of the supply voltage. By investigating a four-dimensional model of the experimental relay system we finally show how a variety of hidden periodic, quasiperiodic and chaotic attractors arise, transform and disappear through different bifurcations. (C) 2015 Elsevier B.V. All rights reserved....

  14. A general definition of the heritable variation that determines the potential of a population to respond to selection.

    Science.gov (United States)

    Bijma, Piter

    2011-12-01

    Genetic selection is a major force shaping life on earth. In classical genetic theory, response to selection is the product of the strength of selection and the additive genetic variance in a trait. The additive genetic variance reflects a population's intrinsic potential to respond to selection. The ordinary additive genetic variance, however, ignores the social organization of life. With social interactions among individuals, individual trait values may depend on genes in others, a phenomenon known as indirect genetic effects. Models accounting for indirect genetic effects, however, lack a general definition of heritable variation. Here I propose a general definition of the heritable variation that determines the potential of a population to respond to selection. This generalizes the concept of heritable variance to any inheritance model and level of organization. The result shows that heritable variance determining potential response to selection is the variance among individuals in the heritable quantity that determines the population mean trait value, rather than the usual additive genetic component of phenotypic variance. It follows, therefore, that heritable variance may exceed phenotypic variance among individuals, which is impossible in classical theory. This work also provides a measure of the utilization of heritable variation for response to selection and integrates two well-known models of maternal genetic effects. The result shows that relatedness between the focal individual and the individuals affecting its fitness is a key determinant of the utilization of heritable variance for response to selection.

  15. Soil Chemical Property Changes in Eggplant/Garlic Relay Intercropping Systems under Continuous Cropping

    Science.gov (United States)

    Wang, Mengyi; Wu, Cuinan; Cheng, Zhihui; Meng, Huanwen; Zhang, Mengru; Zhang, Hongjing

    2014-01-01

    Soil sickness is a critical problem for eggplant (Solanum melongena L.) under continuous cropping that affects sustainable eggplant production. Relay intercropping is a significant technique on promoting soil quality, improving eco-environment, and raising output. Field experiments were conducted from September 2010 to November 2012 in northwest China to determine the effects of relay intercropping eggplant with garlic (Allium sativum L.) on soil enzyme activities, available nutrient contents, and pH value under a plastic tunnel. Three treatments were in triplicate using randomized block design: eggplant monoculture (CK), eggplant relay intercropping with normal garlic (NG) and eggplant relay intercropping with green garlic (GG). The major results are as follows: (1) the activities of soil invertase, urease, and alkaline phosphatase were generally enhanced in NG and GG treatments; (2) relay intercropping significantly increased the soil available nutrient contents, and they were mostly higher in GG than NG. On April 11, 2011, the eggplant/garlic co-growth stage, the available nitrogen content in GG was 76.30 mg·kg−1, significantly higher than 61.95 mg·kg−1 in NG. For available potassium on April 17, 2012, they were 398.48 and 387.97 mg·kg−1 in NG and GG, both were significantly higher than 314.84 mg·kg−1 in CK; (3) the soil pH showed a significantly higher level in NG treatment, but lower in GG treatment compared with CK. For the last samples in 2012, soil pH in NG and GG were 7.70 and 7.46, the highest and lowest one among them; (4) the alkaline phosphatase activity and pH displayed a similar decreasing trend with continuous cropping. These findings indicate that relay intercropping eggplant with garlic could be an ideal farming system to effectively improve soil nutrient content, increase soil fertility, and alleviate soil sickness to some extent. These findings are important in helping to develop sustainable eggplant production. PMID:25340875

  16. Selection by pollinators on floral traits in generalized Trollius ranunculoides (Ranunculaceae along altitudinal gradients.

    Directory of Open Access Journals (Sweden)

    Zhi-Gang Zhao

    Full Text Available Abundance and visitation of pollinator assemblages tend to decrease with altitude, leading to an increase in pollen limitation. Thus increased competition for pollinators may generate stronger selection on attractive traits of flowers at high elevations and cause floral adaptive evolution. Few studies have related geographically variable selection from pollinators and intraspecific floral differentiation. We investigated the variation of Trollius ranunculoides flowers and its pollinators along an altitudinal gradient on the eastern Qinghai-Tibet Plateau, and measured phenotypic selection by pollinators on floral traits across populations. The results showed significant decline of visitation rate of bees along altitudinal gradients, while flies was unchanged. When fitness is estimated by the visitation rate rather than the seed number per plant, phenotypic selection on the sepal length and width shows a significant correlation between the selection strength and the altitude, with stronger selection at higher altitudes. However, significant decreases in the sepal length and width of T. ranunculoides along the altitudinal gradient did not correspond to stronger selection of pollinators. In contrast to the pollinator visitation, mean annual precipitation negatively affected the sepal length and width, and contributed more to geographical variation in measured floral traits than the visitation rate of pollinators. Therefore, the sepal size may have been influenced by conflicting selection pressures from biotic and abiotic selective agents. This study supports the hypothesis that lower pollinator availability at high altitude can intensify selection on flower attractive traits, but abiotic selection is preventing a response to selection from pollinators.

  17. relay coordination in the protection of radially-connected power

    African Journals Online (AJOL)

    ... PROTECTION OF. RADIALLY-CONNECTED POWER SYSTEM NETWORK ... Protective relays detect intolerable or unwanted conditions within an assigned area, and then trip or open one ... time, and current transformer ratio errors. 2.2.1.

  18. Outage analysis for underlay cognitive networks using incremental regenerative relaying

    KAUST Repository

    Tourki, Kamel; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

    2013-01-01

    Cooperative relay technology has recently been introduced into cognitive radio (CR) networks to enhance the network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where

  19. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob; Alouini, Mohamed-Slim; Yang, Hongchuan

    2014-01-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes

  20. Reliable quantum communication over a quantum relay channel

    Energy Technology Data Exchange (ETDEWEB)

    Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117, Hungary and Information Systems Research Group, Mathematics and Natural Sciences, Hungarian Ac (Hungary); Imre, Sandor [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117 (Hungary)

    2014-12-04

    We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.

  1. SIMULASI SISTEM KELISTRIKAN KAMAR HOTEL MENGGUNAKAN SMART RELAY

    Directory of Open Access Journals (Sweden)

    I Nyoman Sukarma

    2018-03-01

    Full Text Available Fungsi dari alat key tag atau hotel switch atau key card adalah memutus atau menyambungkan aliran listrik ke dalam suatu area tertentu atau ruang. Key tag memiliki peran penting pada kamar hotel untuk mencegah pemborosan energi pada saat kamar hotel tidak berpenghuni atau belum tersewakan. Untuk itu, penulis merancang simulasi sistem kelistrikan pada kamar hotel yang dikontrol dengan smart relay. Pada simulasi ini digunakan smart relay Zelio Logic buatan Schneider Electric. Pemrograman smart relay ini menggunakan ladder diagram yang disusun menggunakan perangkat lunak ZelioSoft2 dari Schneider Electric. Smart relay menerima sinyal masukan dari sensor, key tag dan sakelar. Sinyal masukan tersebut selanjutnya diproses agar lampu, kotak-kontak, exhaust fan, dan AC (Air Conditioner pada kamar hotel dapat bekerja.

  2. Spreading Sequence System for Full Connectivity Relay Network

    Science.gov (United States)

    Kwon, Hyuck M. (Inventor); Yang, Jie (Inventor); Pham, Khanh D. (Inventor)

    2018-01-01

    Fully connected uplink and downlink fully connected relay network systems using pseudo-noise spreading and despreading sequences subjected to maximizing the signal-to-interference-plus-noise ratio. The relay network systems comprise one or more transmitting units, relays, and receiving units connected via a communication network. The transmitting units, relays, and receiving units each may include a computer for performing the methods and steps described herein and transceivers for transmitting and/or receiving signals. The computer encodes and/or decodes communication signals via optimum adaptive PN sequences found by employing Cholesky decompositions and singular value decompositions (SVD). The PN sequences employ channel state information (CSI) to more effectively and more securely computing the optimal sequences.

  3. Four-Way Relaying in Wireless Cellular Systems

    DEFF Research Database (Denmark)

    Liu, Huaping; Popovski, Petar; De Carvalho, Elisabeth

    2013-01-01

    Two-way relaying in wireless systems has initiated a large research effort during the past few years. Nevertheless, it represents only a specific traffic pattern and it is of interest to investigate other traffic patterns where such a simultaneous processing of information flows can bring...... performance advantage. In this paper we consider a \\emph{four-way relaying} scenario, where each of the two Mobile Stations (MSs) has a two-way connection to the same Base Station (BS), while each connection is through a dedicated Relay Station (RS). The RSs are placed in such a way that one RS...... of the new scheme for Decode-and-Forward (DF) operational model for the RS. We compare the performance with a state-of-the-art reference scheme, based on two-way relaying with DF. The results indicate that the achievable rate regions are significantly enlarged for the new scheme....

  4. The distribution choice for the threshold of solid state relay

    International Nuclear Information System (INIS)

    Sun Beiyun; Zhou Hui; Cheng Xiangyue; Mao Congguang

    2009-01-01

    Either normal distribution or Weibull distribution can be accepted as sample distribution of the threshold of solid state relay. By goodness-of-fit method, bootstrap method and Bayesian method, the Weibull distribution is chosen later. (authors)

  5. Overlay cognitive radio systems with adaptive two-way relaying

    KAUST Repository

    Hyadi, Amal

    2013-12-01

    In this paper, we propose a spectrum sharing mechanism with a two-phase two-way relaying protocol for an overlay cognitive network. The system comprises two primary users (PUs) and two secondary users (SUs). One of the SUs acts as a relay for the PUs and gains spectrum sharing as long as he respects outage probability constraints of the primary system. Moreover, we consider that the relaying node performs an optimal power allocation scheme that minimizes the outage performance of the secondary receiver. Closed form expressions for the outage probability are derived for the cases of Decode-and-Forward (DF), Amplify-and-Forward (AF), and adaptive relaying. Numerical simulations are presented to illustrate and compare the obtained results. © 2013 IEEE.

  6. The predictive validity of selection for entry into postgraduate training in general practice: evidence from three longitudinal studies.

    Science.gov (United States)

    Patterson, Fiona; Lievens, Filip; Kerrin, Máire; Munro, Neil; Irish, Bill

    2013-11-01

    The selection methodology for UK general practice is designed to accommodate several thousand applicants per year and targets six core attributes identified in a multi-method job-analysis study To evaluate the predictive validity of selection methods for entry into postgraduate training, comprising a clinical problem-solving test, a situational judgement test, and a selection centre. A three-part longitudinal predictive validity study of selection into training for UK general practice. In sample 1, participants were junior doctors applying for training in general practice (n = 6824). In sample 2, participants were GP registrars 1 year into training (n = 196). In sample 3, participants were GP registrars sitting the licensing examination after 3 years, at the end of training (n = 2292). The outcome measures include: assessor ratings of performance in a selection centre comprising job simulation exercises (sample 1); supervisor ratings of trainee job performance 1 year into training (sample 2); and licensing examination results, including an applied knowledge examination and a 12-station clinical skills objective structured clinical examination (OSCE; sample 3). Performance ratings at selection predicted subsequent supervisor ratings of job performance 1 year later. Selection results also significantly predicted performance on both the clinical skills OSCE and applied knowledge examination for licensing at the end of training. In combination, these longitudinal findings provide good evidence of the predictive validity of the selection methods, and are the first reported for entry into postgraduate training. Results show that the best predictor of work performance and training outcomes is a combination of a clinical problem-solving test, a situational judgement test, and a selection centre. Implications for selection methods for all postgraduate specialties are considered.

  7. Ultra Reliable Short Message Relaying with Wireless Power Transfer

    OpenAIRE

    López, Onel L. Alcaraz; Alves, Hirley; Souza, Richard Demo; Fernández, Evelio Martín García

    2017-01-01

    Abstract We consider a dual-hop wireless network where an energy constrained relay node first harvests energy through the received radio-frequency signal from the source, and then uses the harvested energy to forward the source’s information to the destination node. The throughput and delay metrics are investigated for a decode-and-forward relaying mechanism at finite blocklength regime and delay-limited transmission mode. We consider ultra-reliable communication scenarios under discussio...

  8. Impact Analysis of Electrical Current Characteristics in Relay Function for Electrical and Electronic Protection

    International Nuclear Information System (INIS)

    Syirrazie Che Soh; Harzawadi Hasim

    2013-01-01

    This paper is to study effect of electrical current on relay reaction, which has coil and switch inside the relay. An analysis on the electrical current will be conducted to determine current limitation for relay activation purpose. The result of analysis showing that current characteristic of relay and applied load will present their affect to the relay function performance. Finding from this result will bring the idea to develop a suitable design circuit for electrical and electronic protection. (author)

  9. Optimal Coordination of Distance and Directional Overcurrent Relays Considering Different Network Topologies

    OpenAIRE

    Y. Damchi; J. Sadeh; H. Rajabi Mashhadi

    2015-01-01

    Most studies in relay coordination have focused solely on coordination of overcurrent relays while distance relays are used as the main protection of transmission lines. Since, simultaneous coordination of these two types of relays can provide a better protection, in this paper, a new approach is proposed for simultaneous coordination of distance and directional overcurrent relays (D&DOCRs). Also, pursued by most of the previously published studies, the settings of D&DOCRs are usually determi...

  10. Model-based iterative learning control of Parkinsonian state in thalamic relay neuron

    Science.gov (United States)

    Liu, Chen; Wang, Jiang; Li, Huiyan; Xue, Zhiqin; Deng, Bin; Wei, Xile

    2014-09-01

    Although the beneficial effects of chronic deep brain stimulation on Parkinson's disease motor symptoms are now largely confirmed, the underlying mechanisms behind deep brain stimulation remain unclear and under debate. Hence, the selection of stimulation parameters is full of challenges. Additionally, due to the complexity of neural system, together with omnipresent noises, the accurate model of thalamic relay neuron is unknown. Thus, the iterative learning control of the thalamic relay neuron's Parkinsonian state based on various variables is presented. Combining the iterative learning control with typical proportional-integral control algorithm, a novel and efficient control strategy is proposed, which does not require any particular knowledge on the detailed physiological characteristics of cortico-basal ganglia-thalamocortical loop and can automatically adjust the stimulation parameters. Simulation results demonstrate the feasibility of the proposed control strategy to restore the fidelity of thalamic relay in the Parkinsonian condition. Furthermore, through changing the important parameter—the maximum ionic conductance densities of low-threshold calcium current, the dominant characteristic of the proposed method which is independent of the accurate model can be further verified.

  11. Modeling and Simulation of Out of Step Blocking Relay for

    Directory of Open Access Journals (Sweden)

    Ahmed A. Al Adwani

    2013-05-01

    Full Text Available  This paper investigates a power swing effect on a distance protection relay performance installed on (HV/EHV transmission line as well as power system stability. A conventional distance relay can’t properly operate under transient stability conditions; therefore, it cause mol-operation, and it will adversely impact on its trip signals. To overcome this problem, the Out Of Step (OOS relay has modeled and simulated to joint with distance relay to supervise and control on its trip signals response. The setting characteristics technique of the OOS based on concentric polygons scheme method to detect power swing under transient stability situation.         This study ia a modeling and simulating using (Maltab\\ Simulink software. A Two relays had been  performed   and  tested  with  two equivalents network connected to ends.      The results of this study showed an activity and reliability of this way to control the distance relay response under a transient stability conditions and it indicated the possibility to find out faults which may occur at period of power swing

  12. Secrecy Capacity of a Class of Orthogonal Relay Eavesdropper Channels

    Directory of Open Access Journals (Sweden)

    Aggarwal Vaneet

    2009-01-01

    Full Text Available The secrecy capacity of relay channels with orthogonal components is studied in the presence of an additional passive eavesdropper node. The relay and destination receive signals from the source on two orthogonal channels such that the destination also receives transmissions from the relay on its channel. The eavesdropper can overhear either one or both of the orthogonal channels. Inner and outer bounds on the secrecy capacity are developed for both the discrete memoryless and the Gaussian channel models. For the discrete memoryless case, the secrecy capacity is shown to be achieved by a partial decode-and-forward (PDF scheme when the eavesdropper can overhear only one of the two orthogonal channels. Two new outer bounds are presented for the Gaussian model using recent capacity results for a Gaussian multiantenna point-to-point channel with a multiantenna eavesdropper. The outer bounds are shown to be tight for two subclasses of channels. The first subclass is one in which the source and relay are clustered, and the eavesdropper receives signals only on the channel from the source and the relay to the destination, for which the PDF strategy is optimal. The second is a subclass in which the source does not transmit to the relay, for which a noise-forwarding strategy is optimal.

  13. Test on digital transmission by carrier relay

    Energy Technology Data Exchange (ETDEWEB)

    Tahara, Taka; Yasuda, Katsuhiko

    1988-09-01

    Though the analog system was applied to the carrier relay system, together with the transmission route, owned/operated by Chugoku Electric Power, accompanying the digitalization of microwave wireless communication, the method to apply the existing analog system signal station unit, to the digital transmission route, came to be required to be discussed. In case of that application, it is feared for a false signal output to be made, with the impossibility of detecting the bit error, characteristic on the digital transmission route. Therefore, by using the microwave wireless communication between Mihara transformation station and Onomichi control station, a transmission test was made on a signal station of phase wave comparison system. As a result, it was known that the false signal output, produced at the detection width of 2ms at present, could be prevented by fixing the detection width to be 1 or 0.5ms and that the lock time ratio could not be maintained at the detection width of 0.5ms. It was further known that the detection width of 1ms only satisfied the condition, which could be secured by the modification only in timer of the bit error detection at signal station. 1 references, 6 figures, 4 tables.

  14. A SDP based design of relay precoding for the power minimization of MIMO AF-relay networks

    KAUST Repository

    Rao, Anlei

    2015-09-11

    Relay precoding for multiple-input and multiple-output (MIMO) relay networks has been approached by either optimizing the efficiency performance with given power consumption constraints or minimizing the power consumption with quality-of-service (QoS) requirements. For the later type design, previous works has worked on minimizing the approximated power consumption. In this paper, exact power consumption for all relays is derived into a quadratic form by diagonalizing the minimum-square error (MSE) matrix, and the relay precoding matrix is designed by optimizing this quadratic form with the help of semidefinite programming (SDP) relaxation. Our simulation results show that such a design can achieve a gain of around 3 dB against the previous design, which optimized the approximated power consumption. © 2015 IEEE.

  15. STUDI ANALISIS KOORDINASI OVER CURRENT RELAY (OCR) DAN GROUND FAULT RELAY (GFR) PADA RECLOSER DI SALURAN PENYULANG PENEBEL

    OpenAIRE

    I Dewa Gde Agung Budhi Udiana; I G Dyana Arjana; Tjok Gede Indra Partha

    2017-01-01

    Short circuit causing over current problem and can might causing interference of the equipment performance such as distribution transformers also causing widespread disruption occurred. In resolving such interference is required as protection system on the distribution system. Seeing all above is needed coordination between the supporting component of the protection system which is consisted of Over Current Relay (OCR) and Ground Fault Relay (GFR). The research was conducted at PT. PLN (Perse...

  16. Selected Cardiovascular Risk Markers in Vegetarians and Subjects of General Population.

    Science.gov (United States)

    Valachovičová, Martina; Príbojová, Jana; Urbánek, Vladimír; Bírošová, Lucia

    2017-12-01

    Besides genetic factors there are environmental effects including nutritional habits which can influence the risk of age-related diseases. The aim of the study was to assess the age dependence of selected cardiovascular risk markers in two groups of subjects with different nutritional pattern. In 470 long-term vegetarians and 478 subjects of general population the following indicators were measured: total cholesterol, HDL-cholesterol, triacylglycerol, glucose, insulin concentrations, LDL-cholesterol, atherogenic index and insulin resistance IR(HOMA) were also calculated in studied subjects. Obtained data were evaluated according to age decades. Vegetarian vs. non-vegetarian concentrations of total cholesterol, LDL-cholesterol, insulin, and values of atherogenic index and IR(HOMA) were significantly reduced in all age decades. Vegetarian vs. non-vegetarian triacalglycerol concentrations were significantly reduced from 4th–7th decade. Vegetarian average decade values of all lipid parameters were in reference range. In non-vegetarian group, the risk average values of total cholesterol (>5.2 mmol/l) were found from 5th–7th decade, LDL-cholesterol (>3.3 mmol/l) in 7th decade and atherogenic index (>4) in 6th–7th decade. In vegetarians vs. non-vegetarians were noted the average decade values for total cholesterol ranging from 4.01–4.59 vs. 4.48–5.67 mmol/l, for triacylglycerols 1.00–1.33 vs. 1.13–1.74 mmol/l, for LDL-cholesterol 2.03–2.58 vs. 2.43–3.49 mmol/l, for atherogenic index 2.72–3.31 vs. 3.05–4.21 and for IR(HOMA) 0.99–1.15 vs. 1.15–1.84. Our data show significantly reduced mean age decade values of lipid and non-lipid cardiovascular risk markers in all adult vegetarians. Smaller changes of markers between decades compared to non-vegetarians document a protective effect of vegetarian nutrition in prevention of cardiovascular disease. Copyright© by the National Institute of Public Health, Prague 2017

  17. Sum-Rate Enhancement in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2016-09-20

    In this paper, we consider a multiuser multipleinput multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting (EH) relays and multiple destinations. All the nodes are equipped with multiple antennas. The EH and information decoding (ID) tasks at the relays and destinations are separated over the time, which is termed as the time switching (TS) scheme. As optimal solutions for the sum-rate maximization problems of BC channels and the MIMO interference channels are hard to obtain, the end-to-end sum rate maximization problem of a multiuser MIMO DF relay BC channel is even harder. In this paper, we propose to tackle a simplified problem where we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relaydestination channels using an algorithm similar to the BD method. In order to show the relevance of our low complex proposed solution, we compare it to the minimum mean-square error (MMSE) solution that was shown in the literature to be equivalent to the solution of the sum-rate maximization in MIMO broadcasting interfering channels. We also investigate the time division multiple access (TDMA) solution which separates all the information transmissions from the source to the relays and from the relays to the destinations over time. We provide numerical results to show the relevance of our proposed solution, in comparison with the no co-channel interference (CCI) case, the TDMA based solution and the MMSE based solution.

  18. Modified Dynamic Decode-and-Forward Relaying Protocol for Type II Relay in LTE-Advanced and Beyond

    KAUST Repository

    Nam, Sung Sik

    2016-11-29

    In this paper, we propose a modified dynamic decode-and-forward (MoDDF) relaying protocol to meet the critical requirements for user equipment (UE) relays in next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed MoDDF realizes the fast jump-in relaying and the sequential decoding with an application of random codeset to encoding and re-encoding process at the source and the multiple UE relays, respectively. A subframe-by-subframe decoding based on the accumulated (or buffered) messages is employed to achieve energy, information, or mixed combining. Finally, possible early termination of decoding at the end user can lead to the higher spectral efficiency and more energy saving by reducing the frequency of redundant subframe transmission and decoding. These attractive features eliminate the need of directly exchanging control messages between multiple UE relays and the end user, which is an important prerequisite for the practical UE relay deployment. Copyright: © 2016 Nam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  19. Sum-Rate Enhancement in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma; Salem, Ahmed Sultan; Alouini, Mohamed-Slim

    2016-01-01

    In this paper, we consider a multiuser multipleinput multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting (EH) relays and multiple destinations. All the nodes are equipped with multiple antennas. The EH and information decoding (ID) tasks at the relays and destinations are separated over the time, which is termed as the time switching (TS) scheme. As optimal solutions for the sum-rate maximization problems of BC channels and the MIMO interference channels are hard to obtain, the end-to-end sum rate maximization problem of a multiuser MIMO DF relay BC channel is even harder. In this paper, we propose to tackle a simplified problem where we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relaydestination channels using an algorithm similar to the BD method. In order to show the relevance of our low complex proposed solution, we compare it to the minimum mean-square error (MMSE) solution that was shown in the literature to be equivalent to the solution of the sum-rate maximization in MIMO broadcasting interfering channels. We also investigate the time division multiple access (TDMA) solution which separates all the information transmissions from the source to the relays and from the relays to the destinations over time. We provide numerical results to show the relevance of our proposed solution, in comparison with the no co-channel interference (CCI) case, the TDMA based solution and the MMSE based solution.

  20. Modified Dynamic Decode-and-Forward Relaying Protocol for Type II Relay in LTE-Advanced and Beyond

    KAUST Repository

    Nam, Sung Sik; Alouini, Mohamed-Slim; Choi, Seyeong

    2016-01-01

    In this paper, we propose a modified dynamic decode-and-forward (MoDDF) relaying protocol to meet the critical requirements for user equipment (UE) relays in next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed MoDDF realizes the fast jump-in relaying and the sequential decoding with an application of random codeset to encoding and re-encoding process at the source and the multiple UE relays, respectively. A subframe-by-subframe decoding based on the accumulated (or buffered) messages is employed to achieve energy, information, or mixed combining. Finally, possible early termination of decoding at the end user can lead to the higher spectral efficiency and more energy saving by reducing the frequency of redundant subframe transmission and decoding. These attractive features eliminate the need of directly exchanging control messages between multiple UE relays and the end user, which is an important prerequisite for the practical UE relay deployment. Copyright: © 2016 Nam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  1. Bit Error Rate Performance Analysis of a Threshold-Based Generalized Selection Combining Scheme in Nakagami Fading Channels

    Directory of Open Access Journals (Sweden)

    Kousa Maan

    2005-01-01

    Full Text Available The severity of fading on mobile communication channels calls for the combining of multiple diversity sources to achieve acceptable error rate performance. Traditional approaches perform the combining of the different diversity sources using either the conventional selective diversity combining (CSC, equal-gain combining (EGC, or maximal-ratio combining (MRC schemes. CSC and MRC are the two extremes of compromise between performance quality and complexity. Some researches have proposed a generalized selection combining scheme (GSC that combines the best branches out of the available diversity resources ( . In this paper, we analyze a generalized selection combining scheme based on a threshold criterion rather than a fixed-size subset of the best channels. In this scheme, only those diversity branches whose energy levels are above a specified threshold are combined. Closed-form analytical solutions for the BER performances of this scheme over Nakagami fading channels are derived. We also discuss the merits of this scheme over GSC.

  2. Two-Way Multi-Antenna Relaying with Simultaneous Wireless Information and Power Transfer

    Directory of Open Access Journals (Sweden)

    Thanaphat Srivantana

    2017-03-01

    Full Text Available In this paper, we propose various kinds of two-way multi-antenna relaying with simultaneous wireless information and power transfer (SWIPT and investigate their performance. Specifically, we first consider a two-way relay network where two single-antenna end nodes communicate with each other through a multi-antenna relay node that is energy constrained. This relay node harvests energy from the two end nodes and use the harvested energy for forwarding their information. Six relaying schemes that support the considered network then build on the power splitting-based relaying and time switching-based relaying protocols. The average bit error rates of these schemes are evaluated and compared by computer simulations considering several network parameters, including the number of relay antennas, power splitting ratio, and energy harvesting time. Such evaluation and comparison provide useful insights into the performance of SWIPT-based two-way multi-antenna relaying.

  3. Comparison of Channel Estimation Protocols for Coherent AF Relaying Networks in the Presence of Additive Noise and LO Phase Noise

    Directory of Open Access Journals (Sweden)

    Stefan Berger

    2010-01-01

    Full Text Available Channel estimation protocols for wireless two-hop networks with amplify-and-forward (AF relays are compared. We consider multiuser relaying networks, where the gain factors are chosen such that the signals from all relays add up coherently at the destinations. While the destinations require channel knowledge in order to decode, our focus lies on the channel estimates that are used to calculate the relay gains. Since knowledge of the compound two-hop channels is generally not sufficient to do this, the protocols considered here measure all single-hop coefficients in the network. We start from the observation that the direction in which the channels are measured determines (1 the number of channel uses required to estimate all coefficient and (2 the need for global carrier phase reference. Four protocols are identified that differ in the direction in which the first-hop and the second-hop channels are measured. We derive a sensible measure for the accuracy of the channel estimates in the presence of additive noise and phase noise and compare the protocols based on this measure. Finally, we provide a quantitative performance comparison for a simple single-user application example. It is important to note that the results can be used to compare the channel estimation protocols for any two-hop network configuration and gain allocation scheme.

  4. Commercialization and Standardization Progress Towards an Optical Communications Earth Relay

    Science.gov (United States)

    Edwards, Bernard L.; Israel, David J.

    2015-01-01

    NASA is planning to launch the next generation of a space based Earth relay in 2025 to join the current Space Network, consisting of Tracking and Data Relay Satellites in space and the corresponding infrastructure on Earth. While the requirements and architecture for that relay satellite are unknown at this time, NASA is investing in communications technologies that could be deployed to provide new communications services. One of those new technologies is optical communications. The Laser Communications Relay Demonstration (LCRD) project, scheduled for launch in 2018 as a hosted payload on a commercial communications satellite, is a critical pathfinder towards NASA providing optical communications services on the next generation space based relay. This paper will describe NASA efforts in the on-going commercialization of optical communications and the development of inter-operability standards. Both are seen as critical to making optical communications a reality on future NASA science and exploration missions. Commercialization is important because NASA would like to eventually be able to simply purchase an entire optical communications terminal from a commercial provider. Inter-operability standards are needed to ensure that optical communications terminals developed by one vendor are compatible with the terminals of another. International standards in optical communications would also allow the space missions of one nation to use the infrastructure of another.

  5. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-07-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying (EIR) scheme with both amplify and forward and decode and forward relaying. We compare the performance of the EIR scheme with the threshold-based incremental relaying (TIR) scheme. It is shown that the efficiency of the TIR scheme is better for lower values of the threshold. However, the efficiency of the TIR scheme for higher values of threshold is outperformed by the EIR. In addition, three new threshold-based adaptive EIR are devised to further improve the efficiency of the EIR scheme. We calculate the packet error rate and the efficiency of these new schemes to provide the analytical insight. © 2014 IEEE.

  6. Implementing Strategic Planning Capabilities Within the Mars Relay Operations Service

    Science.gov (United States)

    Hy, Franklin; Gladden, Roy; Allard, Dan; Wallick, Michael

    2011-01-01

    Since the Mars Exploration Rovers (MER), Spirit and Opportunity, began their travels across the Martian surface in January of 2004, orbiting spacecraft such as the Mars 2001 Odyssey orbiter have relayed the majority of their collected scientific and operational data to and from Earth. From the beginning of those missions, it was evident that using orbiters to relay data to and from the surface of Mars was a vastly more efficient communications strategy in terms of power consumption and bandwidth compared to direct-to-Earth means. However, the coordination between the various spacecraft, which are largely managed independently and on differing commanding timelines, has always proven to be a challenge. Until recently, the ground operators of all these spacecraft have coordinated the movement of data through this network using a collection of ad hoc human interfaces and various, independent software tools. The Mars Relay Operations Service (MaROS) has been developed to manage the evolving needs of the Mars relay network, and specifically to standardize and integrate the relay planning and coordination data into a centralized infrastructure. This paper explores the journey of developing the MaROS system, from inception to delivery and acceptance by the Mars mission users.

  7. Relay-based information broadcast in complex networks

    Science.gov (United States)

    Fan, Zhongyan; Han, Zeyu; Tang, Wallace K. S.; Lin, Dong

    2018-04-01

    Information broadcast (IB) is a critical process in complex network, usually accomplished by flooding mechanism. Although flooding is simple and no prior topological information is required, it consumes a lot of transmission overhead. Another extreme is the tree-based broadcast (TB), for which information is disseminated via a spanning tree. It achieves the minimal transmission overhead but the maintenance of spanning tree for every node is an obvious obstacle for implementation. Motivated by the success of scale-free network models for real-world networks, in this paper, we investigate the issues in IB by considering an alternative solution in-between these two extremes. A novel relay-based broadcast (RB) mechanism is proposed by employing a subset of nodes as relays. Information is firstly forwarded to one of these relays and then re-disseminated to others through the spanning tree whose root is the relay. This mechanism provides a trade-off solution between flooding and TB. On one hand, it saves up a lot of transmission overhead as compared to flooding; on the other hand, it costs much less resource for maintenance than TB as only a few spanning trees are needed. Based on two major criteria, namely the transmission overhead and the convergence time, the effectiveness of RB is confirmed. The impacts of relay assignment and network structures on performance are also studied in this work.

  8. Systematic Network Coding with the Aid of a Full-Duplex Relay

    DEFF Research Database (Denmark)

    Giacaglia, Giuliano; Shi, Xiaomeng; Kim, MinJi

    2013-01-01

    is to deliver a given number of data packets to a receiver with the aid of a relay. The source broadcasts to both the receiver and the relay using one frequency, while the relay uses another frequency for transmissions to the receiver, allowing for a full-duplex operation of the relay. We analyze the decoding...... complexity and delay performance of two types of relays: one that preserves the systematic structure of the code from the source; another that does not. A systematic relay forwards uncoded packets upon reception, but transmits coded packets to the receiver after receiving the first coded packet from...

  9. Alternate MIMO AF relaying networks with interference alignment: Spectral efficient protocol and linear filter design

    KAUST Repository

    Park, Kihong

    2013-02-01

    In this paper, we study a two-hop relaying network consisting of one source, one destination, and three amplify-and-forward (AF) relays with multiple antennas. To compensate for the capacity prelog factor loss of 1/2$ due to the half-duplex relaying, alternate transmission is performed among three relays, and the inter-relay interference due to the alternate relaying is aligned to make additional degrees of freedom. In addition, suboptimal linear filter designs at the nodes are proposed to maximize the achievable sum rate for different fading scenarios when the destination utilizes a minimum mean-square error filter. © 1967-2012 IEEE.

  10. Design Concepts for a Small Space-Based GEO Relay Satellite for Missions Between Low Earth and near Earth Orbits

    Science.gov (United States)

    Bhasin, Kul B.; Warner, Joseph D.; Oleson, Steven; Schier, James

    2014-01-01

    the number of links looking above and below GEO; the detailed design of a GEO SSBS spacecraft bus and its accommodation of the communication payload, and a summary of the trade study that resulted in the selection of the Falcon 9 launch vehicle to deploy the SSBS and its impact on cost reductions per satellite. ======================================================================== Several initiatives have taken place within NASA1 and international space agencies2 to create a human exploration strategy for expanding human presence into the solar system; these initiatives have been driven by multiple factors to benefit Earth. Of the many elements in the strategy one stands out: to send robotic and human missions to destinations beyond Low Earth Orbit (LEO), including cis-lunar space, Near-Earth Asteroids (NEAs), the Moon, and Mars and its moons.3, 4 The time frame for human exploration to various destinations, based on the public information available,1,4 is shown in Figure 1. Advance planning is needed to define how future space communications services will be provided in the new budget environment to meet future space communications needs. The spacecraft for these missions can be dispersed anywhere from below LEO to beyond GEO, and to various destinations within the solar system. NASA's Space Communications and Navigation (SCaN) program office provides communication and tracking services to space missions during launch, in-orbit testing, and operation phases. Currently, SCaN's space networking relay satellites mainly provide services to users below GEO, at Near Earth Orbit (NEO), below LEO, and in deep space. The potential exists for using a space-based relay satellite, located in the vicinity of various solar system destinations, to provide communication space links to missions both below and above its orbit. Such relays can meet the needs of human exploration missions for maximum connectivity to Earth locations and for reduced latency. In the past, several studies

  11. USING THE GENERAL ELECTRIC / MCKINSEY MATRIX IN THE PROCESS OF SELECTING THE CENTRAL AND EAST EUROPEAN MARKETS

    Directory of Open Access Journals (Sweden)

    Nicolae Răzvan Decuseară

    2013-01-01

    Full Text Available Due to limited resources a company cannot serve all potential markets in the world in a manner that all the clients to be satisfied and the business goals achieved, which is why the company should select the most appropriate markets. It can focus on a single product market serving many geographic areas, but may also decide to serve different product markets in a group of selected geographic areas. Due to the large number and diversity of markets that can choose, analyze of the market attractiveness and the selection the most interesting is a complex process. General Electric Matrix/McKinsey has two dimensions, market attractiveness and the competitive strength of the firm, and aims to analyze the strengths and weaknesses of the company in a variety of areas, allowing the company to identify the most attractive markets and to guide managers in allocating resources to these markets, improve the weaker competitive position of the company in emerging markets, or to draw firm unattractive markets. We can say that it is a very efficient tool for the company being used by international market specialists, on one hand to select foreign markets for the company, and on the other hand, to determine the strategy that the firm will be using to internationalize on those markets. At the end of this paper we present a part of a larger study in which we showed how General Electric Matrix/McKinsey it is used specifically in select foreign markets.

  12. A Selected Bibliography of Dictionaries. General Information Series, No. 9. Indochinese Refugee Education Guides.

    Science.gov (United States)

    Center for Applied Linguistics, Arlington, VA.

    This is a selected, annotated bibliography of dictionaries useful to Indochinese refugees. The purpose of this guide is to provide the American teacher or sponsor with information on the use, limitations and availability of monolingual and bilingual dictionaries which can be used by refugees. The bibliography is preceded by notes on problems with…

  13. Selective reversal of muscle relaxation in general anesthesia: focus on sugammadex

    Directory of Open Access Journals (Sweden)

    Sorin J Brull

    2009-04-01

    Full Text Available Sorin J Brull1, Mohamed Naguib21Department of Anesthesiology, Mayo Clinic College of Medicine, Mayo Clinic Hospital, Jacksonville, FL, USA; 2Department of Anesthesiology and Pain Medicine, The University of Texas M D Anderson Cancer Center,  Houston, TX, USAAbstract: Despite the significant improvements in the pharmacology of muscle relaxants in the past six decades, the search for the ideal muscle relaxant continues, mainly because of the incomplete efficacy and persistent side effects associated with their antagonism. Clinical concerns remain about the residual paralysis and hemodynamic side effects associated with the classic pharmacologic reversal agents, the acetylcholinesterase inhibitors. Although the development of the “ideal muscle relaxant” remains illusory, pharmacologic advancements hold promise for improved clinical care and patient safety. Recent clinical advances include the development of short-acting nondepolarizing muscle relaxant agents that have fast onset and a very rapid metabolism that allows reliable and complete recovery; and the development of selective, “designer” reversal agents that are specific for a single drug or class of drugs. This article reviews recent developments in the pharmacology of these selective reversal agents: plasma cholinesterases, cysteine, and sugammadex. Although each of the selective reversal agents is specific in its substrate, the clinical use of the combination of muscle relaxant with its specific reversal agent will allow much greater intraoperative titrating ability, decreased side effect profile, and may result in a decreased incidence of postoperative residual paralysis and improved patient safety.Keywords: selective reversal agents, cysteine, plasma cholinesterases, sugammadex

  14. Comonotonic approximations for a generalized provisioning problem with application to optimal portfolio selection

    NARCIS (Netherlands)

    van Weert, K.; Dhaene, J.; Goovaerts, M.

    2011-01-01

    In this paper we discuss multiperiod portfolio selection problems related to a specific provisioning problem. Our results are an extension of Dhaene et al. (2005) [14], where optimal constant mix investment strategies are obtained in a provisioning and savings context, using an analytical approach

  15. Social phobia, anxiety, oppositional behavior, social skills, and self-concept in children with specific selective mutism, generalized selective mutism, and community controls.

    Science.gov (United States)

    Cunningham, Charles E; McHolm, Angela E; Boyle, Michael H

    2006-08-01

    We compared social phobia, anxiety, oppositional behavior, social skills, and self-concept in three groups: (1) 28 children with specific mutism (who did not speak to teachers but were more likely to speak to parents and peers at home and school); (2) 30 children with generalized mutism (whose speaking was restricted primarily to their homes); and (3) 52 community controls. Children with generalized mutism evidenced higher anxiety at school, and more separation anxiety, OCD, and depressive symptoms at home. Parents and teachers reported that the social phobia and anxiety scores of children in both the specific and generalized mutism subgroups were higher than controls. Children in both the specific and generalized mutism groups evidenced greater deficits in verbal and nonverbal social skills at home and school than controls. Teachers and parents did not report differences in nonverbal measures of social cooperation and conflict resolution and we found no evidence that selective mutism was linked to an increase in externalizing problems such as oppositional behavior or ADHD. Although children with specific mutism speak in a wider range of situations and appear less anxious to their teachers than children with generalized mutism, significant socially phobic behavior and social skills deficits are present in both groups.

  16. Latest Changes to NASA's Laser Communication Relay Demonstration Project

    Science.gov (United States)

    Edwards, Bernard L.; Israel, David J.; Vithlani, Seema K.

    2018-01-01

    Over the last couple of years, NASA has been making changes to the Laser Communications Relay Demonstration Project (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). The changes made makes LCRD more like a future Earth relay system that has both high speed optical and radio frequency links. This will allow LCRD to demonstrate a more detailed concept of operations for a future operational mission critical Earth relay. LCRD is expected to launch in June 2019 and is expected to be followed a couple of years later with a prototype user terminal on the International Space Station. LCRD's architecture will allow it to serve as a testbed in space and this paper will provide an update of its planned capabilities and experiments.

  17. Joint opportunistic scheduling and network coding for bidirectional relay channel

    KAUST Repository

    Shaqfeh, Mohammad

    2013-07-01

    In this paper, we consider a two-way communication system in which two users communicate with each other through an intermediate relay over block-fading channels. We investigate the optimal opportunistic scheduling scheme in order to maximize the long-term average transmission rate in the system assuming symmetric information flow between the two users. Based on the channel state information, the scheduler decides that either one of the users transmits to the relay, or the relay transmits to a single user or broadcasts to both users a combined version of the two users\\' transmitted information by using linear network coding. We obtain the optimal scheduling scheme by using the Lagrangian dual problem. Furthermore, in order to characterize the gains of network coding and opportunistic scheduling, we compare the achievable rate of the system versus suboptimal schemes in which the gains of network coding and opportunistic scheduling are partially exploited. © 2013 IEEE.

  18. Exact performance analysis of decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-06-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the source may or may not be able to communicate directly with the destination. In our study, we consider a regenerative relaying scheme in which the decision to cooperate takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive an exact closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact statistics of each hop. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results.

  19. Telecommunications Relay Support of the Mars Phoenix Lander Mission

    Science.gov (United States)

    Edwards, Charles D., Jr.; Erickson, James K.; Gladden, Roy E.; Guinn, Joseph R.; Ilott, Peter A.; Jai, Benhan; Johnston, Martin D.; Kornfeld, Richard P.; Martin-Mur, Tomas J.; McSmith, Gaylon W.; hide

    2010-01-01

    The Phoenix Lander, first of NASA's Mars Scout missions, arrived at the Red Planet on May 25, 2008. From the moment the lander separated from its interplanetary cruise stage shortly before entry, the spacecraft could no longer communicate directly with Earth, and was instead entirely dependent on UHF relay communications via an international network of orbiting Mars spacecraft, including NASA's 2001 Mars Odyssey (ODY) and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as ESA's Mars Express (MEX) spacecraft. All three orbiters captured critical event telemetry and/or tracking data during Phoenix Entry, Descent and Landing. During the Phoenix surface mission, ODY and MRO provided command and telemetry services, far surpassing the original data return requirements. The availability of MEX as a backup relay asset enhanced the robustness of the surface relay plan. In addition to telecommunications services, Doppler tracking observables acquired on the UHF link yielded an accurate position for the Phoenix landing site.

  20. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

    2012-01-01

    Cooperative relay technology was recently introduced into cognitive radio networks in order to enhance network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. We first provide the exact cumulative density function (CDF) of received signal-to-noise (SNR) over each hop with co-located relays. Then, the CDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. We validate our analysis by showing that simulation results coincide with our analytical results in Rayleigh fading channels. © 2012 IEEE.