WorldWideScience

Sample records for transmission relay loadability

  1. 78 FR 55249 - Transmission Relay Loadability Reliability Standard; Notice of Compliance Filing

    Science.gov (United States)

    2013-09-10

    ...; RM11-16-000] Transmission Relay Loadability Reliability Standard; Notice of Compliance Filing Take.... \\1\\ Transmission Relay Loadability Reliability Standard, Order No. 733, 130 FERC ] 61, 221 (2010..., Order No. 733-B, 136 FERC ] 61,185 (2011). \\2\\ Transmission Relay Loadability Reliability Standard, 138...

  2. 78 FR 21929 - Transmission Relay Loadability Reliability Standard; Notice of Compliance Filing

    Science.gov (United States)

    2013-04-12

    ... Relay Loadability Reliability Standard; Notice of Compliance Filing Take notice that on February 19... Relay Loadability Reliability Standard, Order No. 733, 130 FERC ] 61,221 (2010) (Order No. 733); order..., 136 FERC ] 61,185 (2011). \\2\\ Transmission Relay Loadability Reliability Standard, 138 FERC ] 61,197...

  3. 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...

  4. 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...

  5. 75 FR 16913 - Transmission Relay Loadability Reliability Standard

    Science.gov (United States)

    2010-04-02

    .... 16 U.S.C. 824o(e)(3). Following a selection process, the Commission selected and certified NERC as... boundaries. For example, if one Region has purely performance-based criteria and an adjoining Region has... transfer trip; (2) permissive under-reach transfer trip; (3) directional comparison blocking; and (4...

  6. 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

  7. 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.

  8. 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.

  9. 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....

  10. 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

  11. 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.

  12. Channel allocation and rate adaptation for relayed transmission over correlated fading channels

    KAUST Repository

    Hwang, Kyusung; Hossain, Md Jahangir; Ko, Youngchai; Alouini, Mohamed-Slim

    2009-01-01

    at both the source and relay nodes, we develop an optimal channel allocation and rate adaptation policy for a dual-hop relayed transmission. As such the overall transmit power for the relayed system is minimized while a target packet dropping rate (PDR

  13. Implementation of a microcomputer based distance relay for parallel transmission lines

    International Nuclear Information System (INIS)

    Phadke, A.G.; Jihuang, L.

    1986-01-01

    Distance relaying for parallel transmission lines is a difficult application problem with conventional phase and ground distance relays. It is known that for cross-country faults involving dissimilar phases and ground, three phase tripping may result. This paper summarizes a newly developed microcomputer based relay which is capable of classifying the cross-country fault correctly. The paper describes the principle of operation and results of laboratory tests of this relay

  14. 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.

  15. 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.

  16. Polar On-Line Acquisition Relay and Transmission System (POLARATS)

    Energy Technology Data Exchange (ETDEWEB)

    Yuracko, K.

    2004-07-15

    POLARATS (Polar On-Line Acquisition Relay And Transmission System) is being developed by YAHSGS LLC (YAHSGS) and Oak Ridge National Laboratory (ORNL) to provide remote, unattended monitoring of environmental parameters under harsh environmental conditions. In particular, instrumental design and engineering is oriented towards protection of human health in the Arctic, and with the additional goal of advancing Arctic education and research. POLARATS will obtain and transmit environmental data from hardened monitoring devices deployed in locations important to understanding atmospheric and aquatic pollutant migration as it is biomagnified in Arctic food chains. An Internet- and personal computer (PC)-based educational module will provide real time sensor data, on-line educational content, and will be integrated with workbooks and textbooks for use in middle and high school science programs. The educational elements of POLARATS include an Internet-based educational module that will instruct students in the use of the data and how those data fit into changing Arctic environments and food chains. POLARATS will: (1) Enable students, members of the community, and scientific researchers to monitor local environmental conditions in real time over the Internet; and (2) Provide additional educational benefits through integration with middle- and high-school science curricula. Information will be relayed from POLARATS devices to classrooms and libraries along with custom-designed POLARATS teaching materials that will be integrated into existing curricula to enhance the educational benefits realized from the information obtained.

  17. 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

  18. 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.

  19. 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....

  20. 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.

  1. 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.

  2. Effect of the Primary User Traffic on Cognitive Relaying with Adaptive Transmission

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive-relay system, the secondary user is permitted to transmit data via a relay when the spectrum bands are detected to be free. The miss detection of spectrum sensing and the primary user traffic will affect the data transmission performance of the secondary user. In this paper, we investigate the impact of the status change of the primary user on the bit error rate (BER) of the adaptive transmission of the secondary user in a cognitive-relay system. Numerical results show that the primary user traffic can significantly degrade the BER of the secondary user transmission.

  3. Effect of the Primary User Traffic on Cognitive Relaying with Adaptive Transmission

    KAUST Repository

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

    2012-01-01

    In a cognitive-relay system, the secondary user is permitted to transmit data via a relay when the spectrum bands are detected to be free. The miss detection of spectrum sensing and the primary user traffic will affect the data transmission

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

    KAUST Repository

    Yang, Yuli; Aissa, Sonia

    2011-01-01

    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

  5. 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.

  6. Dual-Hop VLC/RF Transmission System with Energy Harvesting Relay under Delay Constraint

    KAUST Repository

    Rakia, Tamer; Yang, Hong-Chuan; Gebali, Fayez; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, we introduce a dual-hop visible light communication (VLC) / radio frequency (RF) transmission system to extend the coverage of indoor VLC systems. The relay between the two hops is able to harvest light energy from different

  7. Multiuser Radio Resource Allocation for Multiservice Transmission in OFDMA-Based Cooperative Relay Networks

    Directory of Open Access Journals (Sweden)

    Zhang Xing

    2009-01-01

    Full Text Available Abstract The problem of multiservice transmission in OFDMA-based cooperative relay networks is studied comprehensively. We propose a framework to adaptively allocate power, subcarriers, and data rate in OFDMA system to maximize spectral efficiency under the constraints of satisfying multiuser multiservices' QoS requirements. Specifically, first we concentrate on the single-user scenario which considers multiservice transmission in point-to-point cooperative relay network. Based on the analysis of single-user scenario, we extend the multiservice transmission to multiuser point-to-multipoint scenario. Next, based on the framework, we propose several suboptimal radio resource allocation algorithms for multiservice transmissions in OFDMA-based cooperative relay networks to further reduce the computational complexity. Simulation results show that the proposed algorithms yield much higher spectral efficiency and much lower outage probability, which are flexible and efficient for the OFDMA-based cooperative relay system.

  8. Coordinated Transmissions to Direct and Relayed Users in Wireless Cellular Systems

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; Kaneko, Megumi

    2011-01-01

    The ideas of wireless network coding at the physical layer promise high throughput gains in wireless systems with relays and multi–way traffic flows. This gain can be ascribed to two principles: (1) joint transmission of multiple communication flows and (2) usage of a priori information to cancel...... the interference. In this paper we use these principles to devise new transmission schemes in wireless cellular systems that feature both users served directly by the base stations (direct users) and users served through relays (relayed users). We present four different schemes for coordinated transmission...... of uplink and downlink traffic in which one direct and one relayed user are served. These schemes are then used as building blocks in multi–user scenarios, where we present several schemes for scheduling pairs of users for coordinated transmissions. The optimal scheme involves exhaustive search of the best...

  9. Coordinated Direct and Relay Transmission with Interference Cancelation in Wireless Systems

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar

    2011-01-01

    Two-way relaying schemes in wireless systems obtain throughput gain by utilizing two features (1) jointly serve two communication flows, thus implementing network coding and (2) use of information that is a priori known to cancel interference and obtain the desired signal. Based on these principles......, we propose other schemes that bring throughput gains in wireless cellular systems, where relayed and direct transmissions are carried out in coordinated way. The results show that the coordinated transmission exhibit throughput improvement similar to the two–way relaying schemes....

  10. Cross-layer combining of information-guided transmission withnetwork coding relaying for multiuser cognitive radio systems

    KAUST Repository

    Yang, Yuli; Aï ssa, Sonia

    2013-01-01

    For a cognitive radio relaying network, we propose a cross-layer design by combining information-guided transmission at the physical layer and network coding at the network layer. With this design, a common relay is exploited to help

  11. Diversity-Multiplexing Trade-off for Coordinated Relayed Uplink and Direct Downlink Transmissions

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; Sun, Fan

    2013-01-01

    Abstract—There are two basic principles used in wireless network coding to design throughput-efficient schemes: (1) aggregation of communication flows and (2) interference is embraced and subsequently cancelled or mitigated. These principles inspire design of Coordinated Direct/Relay (CDR) schemes......, where each basic transmission involves two flows to a direct and a relayed user. Considering a scenario with relayed uplink and direct downlink, we analyze the Diversity-Multiplexing Tradeoff (DMT) calculating either the exact value or both upper/lower bounds. The CDR scheme is shown to have a higher...

  12. 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.

  13. Transmission Power Adaption for Full-Duplex Relay-Aided Device-to-Device Communication

    Directory of Open Access Journals (Sweden)

    Hui Dun

    2017-03-01

    Full Text Available Device-to-device (D2D communications bring significant improvements of spectral efficiency by underlaying cellular networks. However, they also lead to a more deteriorative interference environment for cellular users, especially the users in severely deep fading or shadowing. In this paper, we investigate a relay-based communication scheme in cellular systems, where the D2D communications are exploited to aid the cellular downlink transmissions by acting as relay nodes with underlaying cellular networks. We modeled two-antenna infrastructure relays employed for D2D relay. The D2D transmitter is able to transmit and receive signals simultaneously over the same frequency band. Then we proposed an efficient power allocation algorithm for the base station (BS and D2D relay to reduce the loopback interference which is inherent due to the two-antenna infrastructure in full-duplex (FD mode. We derived the optimal power allocation problem in closed form under the independent power constraint. Simulation results show that the algorithm reduces the power consumption of D2D relay to the greatest extent and also guarantees cellular users’ minimum transmit rate. Moreover, it also outperforms the existing half-duplex (HD relay mode in terms of achievable rate of D2D.

  14. 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.

  15. Outage Analysis of Cooperative Transmission with Energy Harvesting Relay: Time Switching versus Power Splitting

    Directory of Open Access Journals (Sweden)

    Guanyao Du

    2015-01-01

    Full Text Available This paper investigates the multiuser transmission network with an energy harvesting (EH cooperative relay, where a source transmits independent information to multiple destinations with the help of an energy constrained relay. The relay can harvest energy from the radio frequency (RF signals transmitted from the source, and it helps the multiuser transmission only by consuming the harvested energy. By adopting the time switching and the power splitting relay receiver architectures, we firstly propose two protocols, the time switching cooperative multiuser transmission (TSCMT protocol and the power splitting cooperative multiuser transmission (PSCMT protocol, to enable the simultaneous information processing and EH at the relay for the system. To evaluate the system performance, we theoretically analyze the system outage probability for the two proposed protocols and then derive explicit expressions for each of them, respectively. Numerical results are provided to demonstrate the accuracy of our analytical results and reveal that compared with traditional noncooperative scheme our proposed protocols are green solutions to offer reliable communication and lower system outage probability without consuming additional energy. In particular, for the same transmit power at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain lower system outage probability.

  16. Signal-Noise Ratio Control Subsystem of Digital Equipment for Transmission of "Strela" Relay Protection Commands

    Directory of Open Access Journals (Sweden)

    I. I. Zabenkov

    2012-01-01

    Full Text Available Continuous measurement function of relative noise and interference level in the information transmission channel is considered as an important one for controlling parameters of high-frequency signal. The present paper simulates an algorithm for measuring signal-noise ratio in the transmission channel of high-voltage lines which is used in the digital equipment for transmission of relay protection and emergency automation commands of "Strela" complex.

  17. Relay-Assisted Primary and Secondary Transmissions in Cognitive Radio Networks

    KAUST Repository

    Shafie, Ahmed El

    2016-09-27

    We assume a set of cognitive relay nodes that assists both primary and secondary transmissions in a time-slotted cognitive radio networks. To regulate the channel access of the various nodes in the network, we propose an overlapped spectrum sensing strategy for channel sensing, where the secondary source node senses the channel from the beginning of the time slot and the cognitive relay nodes sense the channel for double the sensing time used by the secondary source node to detect the activities of both the primary and secondary source nodes. Hence, the secondary source node has an intrinsic priority over the relay nodes. The relay nodes help both the primary user and the secondary user to deliver their unsuccessfully decoded packets at their destinations. In a given time slot, the scheduled relay node for data transmission starts its transmission when both the primary and secondary users are sensed to be inactive (i.e. have no data to transmit). We propose two optimization-based formulations with quality-of-service (QoS) constraints involving average queueing delay and average service rate requirements. We investigate both cases of perfect and imperfect spectrum sensing. To further enhance the users\\' QoS requirements, we propose three packet decoding strategies at the relay nodes and compare their performance. We derive an upper bound on the secondary queue average service rate to determine which decoding strategy can achieve that bound. Our numerical results show the benefits of relaying and its ability to enhance the performance of both the primary and secondary users. Moreover, the performance of the proposed schemes is close to the derived upper bound.

  18. Joint Spectrum Sensing and Resource Allocation for OFDM-based Transmission with a Cognitive Relay

    Directory of Open Access Journals (Sweden)

    S. Eman Mahmoodi

    2014-04-01

    Full Text Available In this paper, we investigate the joint spectrum sensing and resource allocation problem to maximize throughput capacity of an OFDM-based cognitive radio link with a cognitive relay. By applying a cognitive relay that uses decode and forward (D&F, we achieve more reliable communications, generating less interference (by needing less transmit power and more diversity gain. In order to account for imperfections in spectrum sensing, the proposed schemes jointly modify energy detector thresholds and allocates transmit powers to all cognitive radio (CR subcarriers, while simultaneously assigning subcarrier pairs for secondary users (SU and the cognitive relay. This problem is cast as a constrained optimization problem with constraints on (1 interference introduced by the SU and the cognitive relay to the PUs; (2 miss-detection and false alarm probabilities and (3 subcarrier pairing for transmission on the SU transmitter and the cognitive relay and (4 minimum Quality of Service (QoS for each CR subcarrier. We propose one optimal and two suboptimal schemes all of which are compared to other schemes in the literature. Simulation results show that the proposed schemes achieve significantly higher throughput than other schemes in the literature for different relay situations.

  19. Relay-Assisted Primary and Secondary Transmissions in Cognitive Radio Networks

    KAUST Repository

    Shafie, Ahmed El; Khattab, Tamer; Salem, Ahmed Sultan

    2016-01-01

    We assume a set of cognitive relay nodes that assists both primary and secondary transmissions in a time-slotted cognitive radio networks. To regulate the channel access of the various nodes in the network, we propose an overlapped spectrum sensing

  20. Dynamic Loadability of Cable Based Transmission Grids

    DEFF Research Database (Denmark)

    Olsen, Rasmus Schmidt

    D project was carried out at three main locations, the head quarters of Energinet.dk in Errits, DTU in Kgs. Lyngby and during a ve months external stay at Kinectrics in Toronto, Canada. At Energinet.dk I gained considerable knowledge about the practical considerations regarding design, installation...... be found in the appendix. This thesis is divided into 9 chapters, plus list of references, appendices, etc. References to literature are denoted in square brackets, e.g. [1], and equations are denoted in parenthesis, e.g. (1.2) where the 1 refers to the chapter number and the 2 refers to the specic...

  1. A Novel Secure Transmission Scheme in MIMO Two-Way Relay Channels with Physical Layer Approach

    Directory of Open Access Journals (Sweden)

    Qiao Liu

    2017-01-01

    Full Text Available Security issue has been considered as one of the most pivotal aspects for the fifth-generation mobile network (5G due to the increasing demands of security service as well as the growing occurrence of security threat. In this paper, instead of focusing on the security architecture in the upper layer, we investigate the secure transmission for a basic channel model in a heterogeneous network, that is, two-way relay channels. By exploiting the properties of the transmission medium in the physical layer, we propose a novel secure scheme for the aforementioned channel mode. With precoding design, the proposed scheme is able to achieve a high transmission efficiency as well as security. Two different approaches have been introduced: information theoretical approach and physical layer encryption approach. We show that our scheme is secure under three different adversarial models: (1 untrusted relay attack model, (2 trusted relay with eavesdropper attack model, and (3 untrusted relay with eavesdroppers attack model. We also derive the secrecy capacity of the two different approaches under the three attacks. Finally, we conduct three simulations of our proposed scheme. The simulation results agree with the theoretical analysis illustrating that our proposed scheme could achieve a better performance than the existing schemes.

  2. Channel allocation and rate adaptation for relayed transmission over correlated fading channels

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

    We consider, in this paper, channel allocation and rate adaptation scheme for relayed transmission over correlated fading channels via cross-layer design. Specifically, jointly considering the data link layer buffer occupancy and channel quality at both the source and relay nodes, we develop an optimal channel allocation and rate adaptation policy for a dual-hop relayed transmission. As such the overall transmit power for the relayed system is minimized while a target packet dropping rate (PDR) due to buffer over flows is guaranteed. In order to find such an optimal policy, the channel allocation and rate adaptation transmission framework is formulated as a constraint Markov decision process (CMDP). The PDR performance of the optimal policy is compared with that of two conventional suboptimal schemes, namely the channel quality based and the buffer occupancy based channel allocation schemes. Numerical results show that for a given power budget, the optimal scheme requires significantly less power than the conventional schemes in order to maintain a target PDR. ©2009 IEEE.

  3. 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.

  4. 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.

  5. 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.

  6. Dual-Hop VLC/RF Transmission System with Energy Harvesting Relay under Delay Constraint

    KAUST Repository

    Rakia, Tamer

    2017-02-09

    In this paper, we introduce a dual-hop visible light communication (VLC) / radio frequency (RF) transmission system to extend the coverage of indoor VLC systems. The relay between the two hops is able to harvest light energy from different artificial light sources and sunlight entering the room. The relay receives data packet over a VLC channel and uses the harvested energy to retransmit it to a mobile terminal over an RF channel. We develop a novel statistical model for the harvested electrical power and analyze the probability of data packet loss. We define a system design parameter (α ∈ [0, 1)) that controls the time dedicated for excess energy harvesting and data packet retransmission. It was found that the parameter has an optimal value which minimizes the packet loss probability. Further more, this optimal value is independent of the RF channel path loss. However, optimal showed inverse dependence on the packet size.

  7. Rate-Optimized Power Allocation for DF-Relayed OFDM Transmission under Sum and Individual Power Constraints

    Directory of Open Access Journals (Sweden)

    Vandendorpe Luc

    2009-01-01

    Full Text Available We consider an OFDM (orthogonal frequency division multiplexing point-to-point transmission scheme which is enhanced by means of a relay. Symbols sent by the source during a first time slot may be (but are not necessarily retransmitted by the relay during a second time slot. The relay is assumed to be of the DF (decode-and-forward type. For each relayed carrier, the destination implements maximum ratio combining. Two protocols are considered. Assuming perfect CSI (channel state information, the paper investigates the power allocation problem so as to maximize the rate offered by the scheme for two types of power constraints. Both cases of sum power constraint and individual power constraints at the source and at the relay are addressed. The theoretical analysis is illustrated through numerical results for the two protocols and both types of constraints.

  8. Downlink Cooperative Broadcast Transmission Based on Superposition Coding in a Relaying System for Future Wireless Sensor Networks.

    Science.gov (United States)

    Liu, Yang; Han, Guangjie; Shi, Sulong; Li, Zhengquan

    2018-06-20

    This study investigates the superiority of cooperative broadcast transmission over traditional orthogonal schemes when applied in a downlink relaying broadcast channel (RBC). Two proposed cooperative broadcast transmission protocols, one with an amplify-and-forward (AF) relay, and the other with a repetition-based decode-and-forward (DF) relay, are investigated. By utilizing superposition coding (SupC), the source and the relay transmit the private user messages simultaneously instead of sequentially as in traditional orthogonal schemes, which means the channel resources are reused and an increased channel degree of freedom is available to each user, hence the half-duplex penalty of relaying is alleviated. To facilitate a performance evaluation, theoretical outage probability expressions of the two broadcast transmission schemes are developed, based on which, we investigate the minimum total power consumption of each scheme for a given traffic requirement by numerical simulation. The results provide details on the overall system performance and fruitful insights on the essential characteristics of cooperative broadcast transmission in RBCs. It is observed that better overall outage performances and considerable power gains can be obtained by utilizing cooperative broadcast transmissions compared to traditional orthogonal schemes.

  9. Low-complexity full-rate transmission scheme with full diversity for two-path relay networks

    KAUST Repository

    Fareed, Muhammad Mehboob; Yang, Hongchuan; Alouini, Mohamed-Slim

    2015-01-01

    Existing full-rate transmission schemes for two-path relay networks typically cannot achieve full diversity while demanding high decoding complexity. In this paper, we present a novel low-complexity full-rate transmission scheme for two-path relay networks to harvest maximum achievable diversity. The proposed scheme adopts block transmission with small block size of four symbols, which greatly reduces the decoding complexity at the receiver. Through the performance analysis of the resulting two-path relay network in terms of the symbol error rate (SER) and diversity order, we show the proposed scheme can achieve full diversity order of four and mimic a 2 \\times 2 multiple-input multiple-output system. Simulations results are provided to validate the mathematical formulation. © 1967-2012 IEEE.

  10. Low-complexity full-rate transmission scheme with full diversity for two-path relay networks

    KAUST Repository

    Fareed, Muhammad Mehboob

    2015-04-01

    Existing full-rate transmission schemes for two-path relay networks typically cannot achieve full diversity while demanding high decoding complexity. In this paper, we present a novel low-complexity full-rate transmission scheme for two-path relay networks to harvest maximum achievable diversity. The proposed scheme adopts block transmission with small block size of four symbols, which greatly reduces the decoding complexity at the receiver. Through the performance analysis of the resulting two-path relay network in terms of the symbol error rate (SER) and diversity order, we show the proposed scheme can achieve full diversity order of four and mimic a 2 \\\\times 2 multiple-input multiple-output system. Simulations results are provided to validate the mathematical formulation. © 1967-2012 IEEE.

  11. 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.

  12. 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.

  13. Relay-assited transmission and radio resource management for wireless networks

    OpenAIRE

    Agustín de Dios, Adrián

    2008-01-01

    La transmisión asistida por relay o transmisión cooperativa es una nueva técnica de diversidad espacial donde aparece un elemento nuevo (un relay o un usuario cooperativo) en la tradicional transmisión punto a punto (fuente a destino). Ahora en la comunicación intervienen tres enlaces: fuente-relay, relay-destino y fuente-destino. El relay, además de asistir a la fuente en la transmisión de un mensaje, permite combatir las degradaciones que puede sufrir el canal como el shadowing y el pathlos...

  14. Time and Energy Efficient Relay Transmission for Multi-Hop Wireless Sensor Networks.

    Science.gov (United States)

    Kim, Jin-Woo; Barrado, José Ramón Ramos; Jeon, Dong-Keun

    2016-06-27

    The IEEE 802.15.4 standard is widely recognized as one of the most successful enabling technologies for short range low rate wireless communications and it is used in IoT applications. It covers all the details related to the MAC and PHY layers of the IoT protocol stack. Due to the nature of IoT, the wireless sensor networks are autonomously self-organized networks without infrastructure support. One of the issues in IoT is the network scalability. To address this issue, it is necessary to support the multi-hop topology. The IEEE 802.15.4 network can support a star, peer-to-peer, or cluster-tree topology. One of the IEEE 802.15.4 topologies suited for the high predictability of performance guarantees and energy efficient behavior is a cluster-tree topology where sensor nodes can switch off their transceivers and go into a sleep state to save energy. However, the IEEE 802.15.4 cluster-tree topology may not be able to provide sufficient bandwidth for the increased traffic load and the additional information may not be delivered successfully. The common drawback of the existing approaches is that they do not address the poor bandwidth utilization problem in IEEE 802.15.4 cluster-tree networks, so it is difficult to increase the network performance. Therefore, to solve this problem in this paper we study a relay transmission protocol based on the standard protocol in the IEEE 802.15.4 MAC. In the proposed scheme, the coordinators can relay data frames to their parent devices or their children devices without contention and can provide bandwidth for the increased traffic load or the number of devices. We also evaluate the performance of the proposed scheme through simulation. The simulation results demonstrate that the proposed scheme can improve the reliability, the end-to-end delay, and the energy consumption.

  15. Time and Energy Efficient Relay Transmission for Multi-Hop Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jin-Woo Kim

    2016-06-01

    Full Text Available The IEEE 802.15.4 standard is widely recognized as one of the most successful enabling technologies for short range low rate wireless communications and it is used in IoT applications. It covers all the details related to the MAC and PHY layers of the IoT protocol stack. Due to the nature of IoT, the wireless sensor networks are autonomously self-organized networks without infrastructure support. One of the issues in IoT is the network scalability. To address this issue, it is necessary to support the multi-hop topology. The IEEE 802.15.4 network can support a star, peer-to-peer, or cluster-tree topology. One of the IEEE 802.15.4 topologies suited for the high predictability of performance guarantees and energy efficient behavior is a cluster-tree topology where sensor nodes can switch off their transceivers and go into a sleep state to save energy. However, the IEEE 802.15.4 cluster-tree topology may not be able to provide sufficient bandwidth for the increased traffic load and the additional information may not be delivered successfully. The common drawback of the existing approaches is that they do not address the poor bandwidth utilization problem in IEEE 802.15.4 cluster-tree networks, so it is difficult to increase the network performance. Therefore, to solve this problem in this paper we study a relay transmission protocol based on the standard protocol in the IEEE 802.15.4 MAC. In the proposed scheme, the coordinators can relay data frames to their parent devices or their children devices without contention and can provide bandwidth for the increased traffic load or the number of devices. We also evaluate the performance of the proposed scheme through simulation. The simulation results demonstrate that the proposed scheme can improve the reliability, the end-to-end delay, and the energy consumption.

  16. Cross-layer combining of information-guided transmission withnetwork coding relaying for multiuser cognitive radio systems

    KAUST Repository

    Yang, Yuli

    2013-02-01

    For a cognitive radio relaying network, we propose a cross-layer design by combining information-guided transmission at the physical layer and network coding at the network layer. With this design, a common relay is exploited to help the communications between multiple secondary source-destination pairs, which allows for a more efficient use of the radio resources, and moreover, generates less interference to primary licensees in the network. Considering the spectrum-sharing constraints on the relay and secondary sources, the achievable data rate of the proposed cross-layer design is derived and evaluated. Numerical results on average capacity and uniform capacity in the network under study substantiate the efficiency of our proposed design. © 2013 IEEE.

  17. 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.

  18. 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.

  19. Low Complexity Transmission Scheme with Full Diversity for Two-Path Relay Networks

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-01-06

    In this work, we present a new low complexity scheme for two-path relay network to harvest maximum achievable diversity. We analyze the performance of the newly proposed two-path relay network by calculating the symbol error rate (SER) for arbitrary location of relays. It is shown that with this newly proposed scheme, two-path relay networks can mimic a 2x2 multiple-input mulitple-output (MIMO) system and achieve full diversity order of four. Simulations results are provided to verify and illustrate the analytical results.

  20. Low Complexity Transmission Scheme with Full Diversity for Two-Path Relay Networks

    KAUST Repository

    Fareed, Muhammad Mehboob; Yang, Hong-Chuan; Alouini, Mohamed-Slim

    2014-01-01

    In this work, we present a new low complexity scheme for two-path relay network to harvest maximum achievable diversity. We analyze the performance of the newly proposed two-path relay network by calculating the symbol error rate (SER) for arbitrary location of relays. It is shown that with this newly proposed scheme, two-path relay networks can mimic a 2x2 multiple-input mulitple-output (MIMO) system and achieve full diversity order of four. Simulations results are provided to verify and illustrate the analytical results.

  1. Evaluation of PLC Channel Capacity and ABER Performances for OFDM-Based Two-Hop Relaying Transmission

    Directory of Open Access Journals (Sweden)

    Sana Ezzine

    2017-01-01

    Full Text Available Powerline network is recognized as a favorable infrastructure for Smart Grid to transmit information in the network thanks to its broad coverage and low cost deployment. The existing works are trying to improve and adapt transmission techniques to reduce Powerline Communication (PLC channel attenuation and exploit the limited bandwidth to support high data rate over long distances. Two-hop relaying BroadBand PLC (BB-PLC system, in which Orthogonal Frequency Division Multiplexing (OFDM is used, is considered in this paper. We derive and compare the PLC channel capacity and the end-to-end Average BER (ABER for OFDM-based direct link (DL BB-PLC system and for OFDM-based two-hop relaying BB-PLC system for Amplify and Forward (AF and Decode and Forward (DF protocols. We analyze the improvements when we consider the direct link in a cooperative communication when the relay node only transmits the correctly decoded signal. Maximum ratio combining is employed at the destination node to detect the transmitted signal. In addition, in this paper, we highlight the impact of the relay location on the channel capacity and ABER for AF and DF transmission protocols. Moreover, an efficient use of the direct link was also investigated in this paper.

  2. 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

  3. Evaluation of PLC Channel Capacity and ABER Performances for OFDM-Based Two-Hop Relaying Transmission

    OpenAIRE

    Ezzine, Sana; Abdelkefi, Fatma; Cances, Jean Pierre; Meghdadi, Vahid; Bouallégue, Ammar

    2017-01-01

    Powerline network is recognized as a favorable infrastructure for Smart Grid to transmit information in the network thanks to its broad coverage and low cost deployment. The existing works are trying to improve and adapt transmission techniques to reduce Powerline Communication (PLC) channel attenuation and exploit the limited bandwidth to support high data rate over long distances. Two-hop relaying BroadBand PLC (BB-PLC) system, in which Orthogonal Frequency Division Multiplexing (OFDM) is u...

  4. 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

  5. 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.

  6. Outage probability of dual-hop FSO fixed gain relay transmission systems

    KAUST Repository

    Zedini, Emna

    2016-12-24

    In this paper, we analyze the end-to-end performance of dual-hop free-space optical (FSO) fixed gain relaying systems in the presence of atmospheric turbulence as well as pointing errors. More specifically, an exact closed-form expression for the outage probability is presented in terms of the bivariate Fox\\'s H function that accounts for both heterodyne detection as well as intensity modulation with direct detection. At high signal-to-noise ratio (SNR) regime, we provide very tight asymptotic result for this performance metric in terms of simple elementary functions. By using dual-hop FSO relaying, we demonstrate a better system performance as compared to the single FSO link. Numerical and Monte-Carlo simulation results are provided to verify the accuracy of the newly proposed results, and a perfect agreement is observed.

  7. Novel adaptive distance relay algorithm considering the operation of 154 kV SFCL in Korean power transmission system

    International Nuclear Information System (INIS)

    Lee, S.; Lee, J.; Song, S.; Yoon, J.; Lee, B.

    2015-01-01

    Highlights: • This paper presents an outline of the new project of the 154 kV SFCL in Korea. • And then we review some protection problems for the application of 154 kV SFCLs. • This paper proposes a new adaptive protection algorithm for 154 kV SFCLs. • The developed algorithm is tested in a simple distance relay system. - Abstract: In general, SFCLs can have a negative impact on the protective coordination in power transmission system because of the variable impedance of SFCLs. It is very important to solve the protection problems of the power system for the successful application of SFCLs to real power transmission system. This paper reviews some protection problems which can be caused by the application of 154 kV SFCLs to power transmission systems in South Korea. And then we propose an adaptive protection algorithm to solve the problems. The adaptive protection algorithm uses the real time information of the SFCL system operation.

  8. 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.

  9. Protection relay of phase-shifting device with thyristor switch for high voltage power transmission lines

    Science.gov (United States)

    Lachugin, V. F.; Panfilov, D. I.; Akhmetov, I. M.; Astashev, M. G.; Shevelev, A. V.

    2014-12-01

    Problems of functioning of differential current protection systems of phase shifting devices (PSD) with mechanically changed coefficient of transformation of shunt transformer are analyzed. Requirements for devices of protection of PSD with thyristor switch are formulated. Based on use of nonlinear models of series-wound and shunt transformers of PSD modes of operation of major protection during PSD, switching to zero load operation and to operation under load and during short circuit operation were studied for testing PSD with failures. Use of the principle of duplicating by devices of differential current protection (with realization of functions of breaking) of failures of separate pares of PSD with thyristor switch was substantiated. To ensure protection sensitivity to the shunt transformer winding short circuit, in particular, to a short circuit that is not implemented in the current differential protection for PSD with mechanical switch, the differential current protection reacting to the amount of primary ampere-turns of high-voltage and low-voltage winding of this transformer was designed. Studies have shown that the use of differential current cutoff instead of overcurrent protection for the shunt transformer wndings allows one to provide the sensitivity during thyristor failure with the formation of a short circuit. The results of simulation mode for the PSD with switch thyristor designed to be installed as switching point of Voskhod-Tatarskaya-Barabinsk 220 kV transmission line point out the efficiency of the developed solutions that ensure reliable functioning of the PSD.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. Adaptive coordination of protective relaying in Ehv transmission using artificial intelligence and parallel processing; Esquema adaptativo para la coordinacion de reles de proteccion en redes de transmission de alta tension incorporando tecnicas de inteligencia artificial y procesamiento en paralelo

    Energy Technology Data Exchange (ETDEWEB)

    Orduna, E; Garces, F; Rivera, J F [Univ. Nacional de San Juan, San Juan (Argentina). Instituto de Energia Eletrica; Handschin, E [Dortmund Univ. (Germany). Lehrstuhl fuer Elektrische Energieversorgung

    1994-12-31

    The protection systems of electric power systems have as function to detect failures as soon possible and isolate the failed component. Considering that the main protection system may fail, protection in the elements adjacent to the failed one must act as a spare, observing an actuation time delay to accomplish selectivity criteria. This work presents the system named CORPRO developed in order to enable the fast determination of adjustments of relays coordination in electric power transmission lines for real time adaptive protection system 9 refs., 8 figs., 4 tabs.

  17. 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.

  18. 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...

  19. Drug-Loadable Calcium Alginate Hydrogel System for Use in Oral Bone Tissue Repair.

    Science.gov (United States)

    Chen, Luyuan; Shen, Renze; Komasa, Satoshi; Xue, Yanxiang; Jin, Bingyu; Hou, Yepo; Okazaki, Joji; Gao, Jie

    2017-05-06

    This study developed a drug-loadable hydrogel system with high plasticity and favorable biological properties to enhance oral bone tissue regeneration. Hydrogels of different calcium alginate concentrations were prepared. Their swelling ratio, degradation time, and bovine serum albumin (BSA) release rate were measured. Human periodontal ligament cells (hPDLCs) and bone marrow stromal cells (BMSCs) were cultured with both calcium alginate hydrogels and polylactic acid (PLA), and then we examined the proliferation of cells. Inflammatory-related factor gene expressions of hPDLCs and osteogenesis-related gene expressions of BMSCs were observed. Materials were implanted into the subcutaneous tissue of rabbits to determine the biosecurity properties of the materials. The materials were also implanted in mandibular bone defects and then scanned using micro-CT. The calcium alginate hydrogels caused less inflammation than the PLA. The number of mineralized nodules and the expression of osteoblast-related genes were significantly higher in the hydrogel group compared with the control group. When the materials were implanted in subcutaneous tissue, materials showed favorable biocompatibility. The calcium alginate hydrogels had superior osteoinductive bone ability to the PLA. The drug-loadable calcium alginate hydrogel system is a potential bone defect reparation material for clinical dental application.

  20. 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 ...

  1. 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.

  2. 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.

  3. 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 ...

  4. 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.

  5. 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.

  6. 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...

  7. Real Time Load Optimisation of Cable Based Transmission Grids

    DEFF Research Database (Denmark)

    Olsen, Rasmus Schmidt; Holbøll, Joachim; Guðmundsdottir, Unnur Stella

    2011-01-01

    Energinet.dk has launched an investigation of dynamic current ratings of cable based transmission grids, where both internal and external parameters are variables. The first topic was to investigate state of the art within calculating the current carrying capacity (ampacity or loadability......) of cables embedded in larger cable systems. Some recently published research has been concerned with dynamic loadability, but such researches are based on many assumptions. It is shown in the paper, that only limited research has been concerned with larger cable grids, and no remarkable work could been...

  8. 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...

  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. 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...

  11. 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...

  12. 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.

  13. 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

  14. 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.

  15. Energy efficient design for MIMO two-way AF multiple relay networks

    KAUST Repository

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

    2014-01-01

    This paper studies the energy efficient transmission and the power allocation problem for multiple two-way relay networks equipped with multi-input multi-output antennas where each relay employs an amplify-and-forward strategy. The goal

  16. On the capacity of multiple cognitive links through common relay under spectrum-sharing constraints

    KAUST Repository

    Yang, Yuli; Aissa, Sonia

    2011-01-01

    In this paper, we consider an underlay cognitive relaying network consisting of multiple secondary users and introduce a cooperative transmission protocol using a common relay to help with the communications between all secondary source

  17. 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

  18. 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.

  19. Detection of maximum loadability limits and weak buses using Chaotic PSO considering security constraints

    International Nuclear Information System (INIS)

    Acharjee, P.; Mallick, S.; Thakur, S.S.; Ghoshal, S.P.

    2011-01-01

    Highlights: → The unique cost function is derived considering practical Security Constraints. → New innovative formulae of PSO parameters are developed for better performance. → The inclusion and implementation of chaos in PSO technique is original and unique. → Weak buses are identified where FACTS devices can be implemented. → The CPSO technique gives the best performance for all the IEEE standard test systems. - Abstract: In the current research chaotic search is used with the optimization technique for solving non-linear complicated power system problems because Chaos can overcome the local optima problem of optimization technique. Power system problem, more specifically voltage stability, is one of the practical examples of non-linear, complex, convex problems. Smart grid, restructured energy system and socio-economic development fetch various uncertain events in power systems and the level of uncertainty increases to a great extent day by day. In this context, analysis of voltage stability is essential. The efficient method to assess the voltage stability is maximum loadability limit (MLL). MLL problem is formulated as a maximization problem considering practical security constraints (SCs). Detection of weak buses is also important for the analysis of power system stability. Both MLL and weak buses are identified by PSO methods and FACTS devices can be applied to the detected weak buses for the improvement of stability. Three particle swarm optimization (PSO) techniques namely General PSO (GPSO), Adaptive PSO (APSO) and Chaotic PSO (CPSO) are presented for the comparative study with obtaining MLL and weak buses under different SCs. In APSO method, PSO-parameters are made adaptive with the problem and chaos is incorporated in CPSO method to obtain reliable convergence and better performances. All three methods are applied on standard IEEE 14 bus, 30 bus, 57 bus and 118 bus test systems to show their comparative computing effectiveness and

  20. 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...

  1. 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....

  2. 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

  3. 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)

  4. 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.

  5. 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...

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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....

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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. ...

  19. 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.

  20. All-optical loadable and erasable memory cell design based on inversionless lasing and electromagnetically induced transparency effects

    International Nuclear Information System (INIS)

    Gholipour Verki, N; HajiBadali, A; Abbasian, K; Rostami, A

    2011-01-01

    A loadable and erasable all-optical memory cell is designed by using two coupled micro-ring resonators with electromagnetically induced transparency (EIT) and lasing without inversion (LWI). To read out stored data, an additional phase is introduced in the upper ring resonator due to EIT. To compensate the fibre loss, use is made of LWI. The EIT is induced by inserting Λ-type three level quantum dots in the right-hand half of the upper ring and LWI is implemented by inserted Y-type four level quantum dots in the left-hand half of both rings. This optical memory cell can operate at a low light power level corresponding to several photons.

  1. 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.

  2. Impact of intra-flow network coding on the relay channel performance: an analytical study

    OpenAIRE

    Apavatjrut , Anya; Goursaud , Claire; Jaffrès-Runser , Katia; Gorce , Jean-Marie

    2012-01-01

    International audience; One of the most powerful ways to achieve trans- mission reliability over wireless links is to employ efficient coding techniques. This paper investigates the performance of a transmission over a relay channel where information is protected by two layers of coding. In the first layer, transmission reliability is ensured by fountain coding at the source. The second layer incorporates network coding at the relay node. Thus, fountain coded packets are re-encoded at the relay...

  3. On the capacity of multiple cognitive links through common relay under spectrum-sharing constraints

    KAUST Repository

    Yang, Yuli

    2011-06-01

    In this paper, we consider an underlay cognitive relaying network consisting of multiple secondary users and introduce a cooperative transmission protocol using a common relay to help with the communications between all secondary source-destination pairs for higher throughput and lower realization complexity. A whole relay-assisted transmission procedure is composed of multiple access phase and broadcast phase, where the relay is equipped with multiple antennas, and the secondary sources and destinations are single-antenna nodes. Considering the spectrum-sharing constraints on the secondary sources and the relay, we analyze the capacity behaviors of the underlay cognitive relaying network under study. The corresponding numerical results provide a convenient tool for the presented network design and substantiate a distinguishing feature of introduced design in that multiple secondary users\\' communications do not rely on multiple relays, hence allowing for a more efficient use of the radio resources. © 2011 IEEE.

  4. 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...

  5. 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...

  6. Multi-flow scheduling for coordinated direct and relayed users in cellular systems

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; Kaneko, Megumi

    2013-01-01

    . Such are the Coordinated Direct/Relay (CDR) schemes, where each basic transmission involves two flows to a direct and a relayed user. Usage of MFT schemes as building blocks of more complex transmission schemes essentially changes the problem of scheduling, since some of the flows to be scheduled are coupled in a signal...

  7. Frame Allocation and Scheduling for Relay Networks in the LTE Advanced Standard

    OpenAIRE

    Roth, Stefan

    2010-01-01

    The use of relays is seen as a promising way to extend cell coverage and increase rates in LTE Advanced networks. Instead of increasing the number of base stations (BS), relays with lower cost could provide similar gains. A relay will have a wireless link to the closest BS as only connection to the core network and will cover areas close to the cell edge or other areas with limited rates. Performing transmissions in several hops (BS-relay & relay-user) requires more radio resources than u...

  8. 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

  9. 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.   

  10. 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

  11. 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

  12. 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...

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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

  20. A study on Relay Effect via Magnetic Resonant Coupling for Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Rashid N.A.

    2016-01-01

    Full Text Available Wireless power transfer (WPT transmits electrical energy from a power source to an electrical load wirelessly or without any conductors. The capability of WPT to transmit the energy is limited. Therefore, a relay was introduced to increase the distance of the WPT capabilities. The effect of the relay has been investigated to extend the energy transfer distance. The effect of relay was demonstrated by placing a relay coil between transmitter and receiver, relay biased to transmitter and placing two relay coils in the designed system. Experimental results are provided to prove the concept of the relay effect. The power transmission efficiency can be achieved up to 75% at 1 meter distance.

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

    KAUST Repository

    Chelli, Ali

    2012-12-01

    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 the transmitted messages over the different HARQ rounds and tries to decode the data packet. In case of successful decoding at the relay, both the relay and the source cooperate to transmit the message to the destination. A maximum number M of HARQ rounds is considered. The channel realizations are independent for different HARQ rounds. We assume Rayleigh fading channels for the links source-relay, source-destination, and relay-destination. We investigate the performance of HARQ-IR over relay channel from an information theoretic perspective. Analytical expressions are derived for the information outage probability, the average number of transmissions, and the average transmission rate. We illustrate through our investigation the benefit of relaying. We also show the impact of the target outage probability and the maximum number M of HARQ rounds on the outage probability, the average number of transmissions, and the average transmission rate. © 2012 IEEE.

  2. Coordination of Regenerative Relays and Direct Users in Wireless Cellular Networks

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar

    2011-01-01

    The area of wireless cooperation/relaying has recently been significantly enriched by the ideas of wireless network coding (NC), which bring substantial gains in spectral efficiency. These gains have mainly been demonstrated in scenarios with two-way relaying. Inspired by the ideas of wireless NC......, recently we have proposed techniques for coordinated direct/relay (CDR) transmissions. These techniques embrace the interference among the communication flows to/from direct and relayed users, leveraging on the fact that the interference can be subsequently canceled. Hence, by allowing simultaneous...... transmissions, spectral efficiency is increased. In our prior work, we have considered CDR with non-regenerative relay that uses Amplify-and-Forward (AF). In this paper we consider the case of regenerative Decode-and-Forward (DF) relay. This refers also to joint decoding of the interfering flows received over...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Resource allocation for relay assisted cognitive radio networks

    KAUST Repository

    Zafar, Ammar

    2012-09-16

    In this paper, we present two optimal resource allocation schemes that maximize throughput and symbol correct rate (SCR). The throughput and SCR are derived. The derived throughput and SCR are optimized with respect to the sensing time, the source 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.

  8. 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.

  9. Improving throughput of single-relay DF channel using linear constellation precoding

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-08-01

    In this letter, we propose a transmission scheme to improve the overall throughput of a cooperative communication system with single decode-and-forward relay. Symbol error rate and throughput analysis of the new scheme are presented to facilitate the performance comparison with the existing decode-and-forward relaying schemes. Simulation results are further provided to corroborate the analytical results. © 2012 IEEE.

  10. Improving throughput of single-relay DF channel using linear constellation precoding

    KAUST Repository

    Fareed, Muhammad Mehboob; Yang, Hongchuan; Alouini, Mohamed-Slim

    2014-01-01

    In this letter, we propose a transmission scheme to improve the overall throughput of a cooperative communication system with single decode-and-forward relay. Symbol error rate and throughput analysis of the new scheme are presented to facilitate the performance comparison with the existing decode-and-forward relaying schemes. Simulation results are further provided to corroborate the analytical results. © 2012 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. 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.

  13. 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...

  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. Spatially Controlled Relay Beamforming

    Science.gov (United States)

    Kalogerias, Dionysios

    This thesis is about fusion of optimal stochastic motion control and physical layer communications. Distributed, networked communication systems, such as relay beamforming networks (e.g., Amplify & Forward (AF)), are typically designed without explicitly considering how the positions of the respective nodes might affect the quality of the communication. Optimum placement of network nodes, which could potentially improve the quality of the communication, is not typically considered. However, in most practical settings in physical layer communications, such as relay beamforming, the Channel State Information (CSI) observed by each node, per channel use, although it might be (modeled as) random, it is both spatially and temporally correlated. It is, therefore, reasonable to ask if and how the performance of the system could be improved by (predictively) controlling the positions of the network nodes (e.g., the relays), based on causal side (CSI) information, and exploitting the spatiotemporal dependencies of the wireless medium. In this work, we address this problem in the context of AF relay beamforming networks. This novel, cyber-physical system approach to relay beamforming is termed as "Spatially Controlled Relay Beamforming". First, we discuss wireless channel modeling, however, in a rigorous, Bayesian framework. Experimentally accurate and, at the same time, technically precise channel modeling is absolutely essential for designing and analyzing spatially controlled communication systems. In this work, we are interested in two distinct spatiotemporal statistical models, for describing the behavior of the log-scale magnitude of the wireless channel: 1. Stationary Gaussian Fields: In this case, the channel is assumed to evolve as a stationary, Gaussian stochastic field in continuous space and discrete time (say, for instance, time slots). Under such assumptions, spatial and temporal statistical interactions are determined by a set of time and space invariant

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Near optimal power allocation algorithm for OFDM-based cognitive using adaptive relaying strategy

    KAUST Repository

    Soury, Hamza; Bader, Faouzi; Shaat, Musbah M R; Alouini, Mohamed-Slim

    2012-01-01

    Relayed transmission increases the coverage and achievable capacity of communication systems. Adaptive relaying scheme is a relaying technique by which the benefits of the amplifying or decode and forward techniques can be achieved by switching the forwarding technique according to the quality of the signal. A cognitive Orthogonal Frequency-Division Multiplexing (OFDM) based adaptive relaying protocol is considered in this paper. The objective is to maximize the capacity of the cognitive radio system while ensuring that the interference introduced to the primary user is below the tolerated limit. A Near optimal power allocation in the source and the relay is presented for two pairing techniques such that the matching and random pairing. The simulation results confirm the efficiency of the proposed adaptive relaying protocol, and the consequence of choice of pairing technique. © 2012 ICST.

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    KAUST Repository

    Al-Habob, Ahmed A.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2017-01-01

    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

  10. Secure amplify-and-forward untrusted relaying networks using cooperative jamming and zero-forcing cancelation

    KAUST Repository

    Park, Kihong; Alouini, Mohamed-Slim

    2015-01-01

    In this paper, we investigate secure transmission in untrusted amplify-and-forward half-duplex relaying networks with the help of cooperative jamming at the destination (CJD). Under the assumption of full channel state information (CSI

  11. Cooperative joint precoding in a downlink cellular system with shared relay: Design and performance evaluation

    KAUST Repository

    Kwon, JaeWoo; Park, Kihong; Ko, Youngchai; Yang, Hongchuan

    2012-01-01

    In this paper, we investigate a relay enhanced cellular system, where a relay station is located in the overlap area served by two base stations. We propose cooperative joint precoding schemes for the downlink transmission of such relay enhanced cellular system to maximize the system capacity while minimizing the interference at both the relay station and the mobile stations. We formulate the optimization problems to maximize the system capacity and design the multiuser precoding vectors at each base station and the relay station. We quantify the ergodic rate performance of the proposed multiuser precoding schemes through statistical analysis. The extensively derived ergodic expressions will facilitate the accurate performance evaluation of the proposed transmission schemes. Numerical results show that the proposed schemes can effectively cancel the interference and improve the sum rate and the outage performance for cell edge users. © 2002-2012 IEEE.

  12. 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...

  13. Rate regions for coordination of Decode-and-Forward relays and direct users

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar

    2012-01-01

    Recently, the ideas of wireless network coding (NC) has significantly enriched the area of wireless cooperation/relaying. They bring substantial gains in spectral efficiency mainly in scenarios with two–way relaying. Inspired by the ideas of wireless NC, recently we have proposed techniques...... for coordinated direct/relay (CDR) transmissions. Leveraging on the fact that the interference can be subsequently canceled, these techniques embrace the interference among the communication flows to/from direct and relayed users. Hence, by allowing simultaneous transmissions, spectral efficiency is increased....... In our prior work, we have proposed CDR with Decode–and–Forward (DF) relay in two scenarios. In this paper, we extend the two existing regenerative CDR schemes and proposed for the other two scenarios such that all schemes benefit from the aforementioned principle of containing the interference...

  14. Cooperative joint precoding in a downlink cellular system with shared relay: Design and performance evaluation

    KAUST Repository

    Kwon, JaeWoo

    2012-10-01

    In this paper, we investigate a relay enhanced cellular system, where a relay station is located in the overlap area served by two base stations. We propose cooperative joint precoding schemes for the downlink transmission of such relay enhanced cellular system to maximize the system capacity while minimizing the interference at both the relay station and the mobile stations. We formulate the optimization problems to maximize the system capacity and design the multiuser precoding vectors at each base station and the relay station. We quantify the ergodic rate performance of the proposed multiuser precoding schemes through statistical analysis. The extensively derived ergodic expressions will facilitate the accurate performance evaluation of the proposed transmission schemes. Numerical results show that the proposed schemes can effectively cancel the interference and improve the sum rate and the outage performance for cell edge users. © 2002-2012 IEEE.

  15. 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.

  16. 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...

  17. 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.

  18. Wireless Powered Cooperative Communications: Power-Splitting Relaying With Energy Accumulation (Author’s Manuscript)

    Science.gov (United States)

    2016-03-21

    decreasing power usage, while improving the transmission performance. A key concern of the energy harvesting enabled coop- erative relay communication is the...improving transmission performance via an efficient utiliza- tion of harvested power has been widely studied for conven- tional energy harvesting techniques...can be used as energy sources for cooperative nodes. Moreover, it has been illustrated in [6] that wireless -powered cooperative relay communications

  19. Cell-Edge Multi-User Relaying with Overhearing

    DEFF Research Database (Denmark)

    Sun, Fan; Kim, Tae Min; Paulraj, Arogyaswami

    2013-01-01

    Carefully designed protocols can turn overheard interference into useful side information to allow simultaneous transmission of multiple communication flows and increase the spectral efficiency in interference-limited regime. In this letter, we propose a novel scheme in a typical cell-edge scenar....... By exploiting the overhearing link through proper relay precoding and adaptive receiver processing, rate performance can be significantly improved compared to the conventional transmission which does not utilize overhearing....

  20. 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".

  1. Massive MIMO Relay Systems with Multipair Wireless Information and Power Transfer

    Directory of Open Access Journals (Sweden)

    Hongwu Liu

    2017-01-01

    Full Text Available This paper investigates destination-aided simultaneous wireless information and power transfer (SWIPT for a decode-and-forward relay network, in which massive multiple-input multiple-output antennas are deployed at relay to assist communications among multiple source-destination pairs. During relaying, energy signals are emitted from multiple destinations when multiple sources are sending their information signals to relay. With power splitting and unlimited antennas at relay, asymptotic expression of harvested energy is derived. The analysis reveals that asymptotic harvested energy is independent of fast fading effect of wireless channels; meanwhile transmission powers of each source and destination can be scaled down inversely proportional to the number of relay antennas. To significantly reduce energy leakage interference and multipair interference, zero-forcing processing and maximum-ratio combing/maximum-ratio transmission are employed at relay. Fundamental trade-off between harvested energy and achievable sum rate is quantified. It is shown that asymptotic sum rate is neither convex nor concave with respect to power splitting and destination transmission power. Thus, a one-dimensional embedded bisection algorithm is proposed to jointly determine the optimal power splitting and destination transmission power. It shows that destination-aided SWIPT are beneficial for harvesting energy and increasing sum rate. The significant sum rate improvements of the proposed schemes are verified by numerical results.

  2. An airborne meteorological data collection system using satellite relay /ASDAR/

    Science.gov (United States)

    Bagwell, J. W.; Lindow, B. G.

    1978-01-01

    The paper describes the aircraft to satellite data relay (ASDAR) project which processes information collected by the navigation and data systems of widebody jet aircraft which cross data-sparse areas of the tropics and southern hemisphere. The ASDAR system consists of a data acquisition and control unit to acquire, store, and format latitude, longitude, altitude, wind speed, wind direction, and outside air temperature data; a transmitter to relay the formatted data via satellite to the ground; and a clock to time the data sampling and transmission periods.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel

    2012-12-01

    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.

  8. 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...

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. On the Performance of a Wireless Powered Communication System Using a Helping Relay

    Directory of Open Access Journals (Sweden)

    T. N. Nguyen

    2017-09-01

    Full Text Available This paper studies the outage performance and system throughput of a bidirectional wireless information and power transfer system with a helping relay. The relay helps forward wireless power from the access point (AP to the user, and also the information from the user to the AP in the reverse direction. We assume that the relay uses time switching based energy harvesting protocol. The analytical results provide theoretical insights into the effect of various system parameters, such as time switching factor, source transmission rate, transmitting-power-to-noise ratio to system performance for both amplify-and-forward and decode-and-forward relaying protocols. The optimal time switching ratio is determined in each case to maximize the information throughput from the user to the AP subject to the energy harvesting and consumption balance constraints at both the relay and the user. All of the above analyses are confirmed by Monte-Carlo simulation.

  17. 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.

  18. 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.

  19. 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.

  20. Secure amplify-and-forward untrusted relaying networks using cooperative jamming and zero-forcing cancelation

    KAUST Repository

    Park, Kihong

    2015-12-03

    In this paper, we investigate secure transmission in untrusted amplify-and-forward half-duplex relaying networks with the help of cooperative jamming at the destination (CJD). Under the assumption of full channel state information (CSI), conventional CJD using self-interference cancelation at the destination is efficient when the untrusted relay has no capability to suppress the jamming signal. However, if the source and destination are equipped with a single antenna and the only untrusted relay is equipped with N multiple antennas, it can remove the jamming signal from the received signal by linear filters and the full multiplexing gain of relaying cannot be achievable with the conventional CJD due to the saturation of the secrecy rate at the high transmit power regime. We propose in this paper new CJD scheme where neither destination nor relay can acquire CSI of relay-destination link. Our proposed scheme utilizes zero-forcing cancelation based on known jamming signals instead of self-interference subtraction, while the untrusted relay cannot suppress the jamming signals due to the lack of CSI. We show that the secrecy rate of the proposed scheme can enjoy a half of multiplexing gain in half-duplex relaying while that of conventional CJD is saturated at high transmit power for N ???2. The impact of channel estimation error at the destination is also investigated to show the robustness of the proposed scheme against strong estimation errors.

  1. 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.

  2. Simultaneous energy harvesting and information processing in wireless multiple relays with multiple antennas

    Science.gov (United States)

    Albaaj, Azhar; Makki, S. Vahab A.; Alabkhat, Qassem; Zahedi, Abdulhamid

    2017-07-01

    Wireless networks suffer from battery discharging specially in cooperative communications when multiple relays have an important role but they are energy constrained. To overcome this problem, energy harvesting from radio frequency signals is applied to charge the node battery. These intermediate nodes have the ability to harvest energy from the source signal and use the energy harvested to transmit information to the destination. In fact, the node tries to harvest energy and then transmit the data to destination. Division of energy harvesting and data transmission can be done in two algorithms: time-switching-based relaying protocol and power-splitting-based relaying protocol. These two algorithms also can be applied in delay-limited and delay-tolerant transmission systems. The previous works have assumed a single relay for energy harvesting, but in this article, the proposed method is concentrated on improving the outage probability and throughput by using multiple antennas in each relay node instead of using single antenna. According to our simulation results, when using multi-antenna relays, ability of energy harvesting is increased and thus system performance will be improved to great extent. Maximum ratio combining scheme has been used when the destination chooses the best signal of relays and antennas satisfying the required signal-to-noise ratio.

  3. Achievable Rates of Buffer-Aided Full-Duplex Gaussian Relay Channels

    KAUST Repository

    El Shafie, Ahmed

    2017-10-18

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multipleoutput (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  4. Optimizing Completion Time and Energy Consumption in a Bidirectional Relay Network

    DEFF Research Database (Denmark)

    Liu, Huaping; Sun, Fan; Thai, Chan

    2012-01-01

    consumption required for multiple flows depends on the current channel realizations, transmission methods used and, notably, the relation between the data sizes of different source nodes. In this paper we investigate the shortest completion time and minimal energy consumption in a two-way relay wireless...... arises for the minimal required energy. While the requirement for minimal energy consumption is obvious, the shortest completion time is relevant when certain multi-node network needs to reserve the wireless medium in order to carry out the data exchange among its nodes. The completion time/energy...... network. The system applies optimal time multiplexing of several known transmission methods, including one-way relaying and wireless network coding (WNC). We show that when the relay applies Amplify-and-Forward (AF), both minimizations are linear optimization problems. On the other hand, when the relay...

  5. Mutual Information of Buffer-Aided Full-Duplex Relay Channels

    KAUST Repository

    Shafie, Ahmed El

    2017-04-09

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multiple-output (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  6. Achievable Rates of Buffer-Aided Full-Duplex Gaussian Relay Channels

    KAUST Repository

    El Shafie, Ahmed; Salem, Ahmed Sultan; Krikidis, Ioannis; Al-Dhahir, Naofal; Hamila, Ridha

    2017-01-01

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multipleoutput (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  7. Mutual Information of Buffer-Aided Full-Duplex Relay Channels

    KAUST Repository

    Shafie, Ahmed El; Salem, Ahmed Sultan; Krikidis, Ioannis; Al-Dhahir, Naofal; Hamila, Ridha

    2017-01-01

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multiple-output (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  8. 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 ...

  9. 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

  10. 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....

  11. 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...

  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. 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 ...

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

    KAUST Repository

    Asghari, Vahid Reza; Aissa, Sonia

    2011-01-01

    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

  15. Energy-Efficient Power Allocation for Fixed-Gain Amplify-and-Forward Relay Networks with Partial Channel State Information

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

    2012-01-01

    In this letter, energy-efficient transmission and power allocation for fixed-gain amplify-and-forward relay networks with partial channel state information (CSI) are studied. In the energy-efficiency problem, the total power consumed is minimized

  16. 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.

  17. Two-Layer Coding Rate Optimization in Relay-Aided Systems

    DEFF Research Database (Denmark)

    Sun, Fan

    2011-01-01

    We consider a three-node transmission system, where a source node conveys a data block to a destination node with the help of a half-duplex decode and-forward (DF) relay node. The whole data block is transmitted as a sequence of packets. For reliable transmission in the three-node system, a two...

  18. Evaluation of Potential Relay Locations in a Urban Macro-Cell Scenario with Applicability to LTE-A

    DEFF Research Database (Denmark)

    Rodriguez, Ignacio; Coletti, Claudio; Sørensen, Troels Bundgaard

    2012-01-01

    . This paper presents a measurement-based study focusing on the performance evaluation of the relay backhaul link for different potential relay locations and antenna configurations in a real urban macro-cell scenario. Based on the assumption that a similar network deployment would apply for LTE-A, a fully......Relay base stations are expected to play an important role in extending coverage for beyond 3G networks, such as LTE-A. However, the signal quality experienced on the backhaul link between the macro-cell and the relay node has a major impact on the performance of the multi-hop transmission...... operational 3G network has been used for measuring both received signal strength and Signal-to-Interference-Ratio (SIR). Furthermore, the results have been used to estimate the performance of the multi-hop transmission under simplifying assumptions. The experimental results show that by increasing the relay...

  19. Asymptotic Analysis of Large Cooperative Relay Networks Using Random Matrix Theory

    Directory of Open Access Journals (Sweden)

    H. Poor

    2008-04-01

    Full Text Available Cooperative transmission is an emerging communication technology that takes advantage of the broadcast nature of wireless channels. In cooperative transmission, the use of relays can create a virtual antenna array so that multiple-input/multiple-output (MIMO techniques can be employed. Most existing work in this area has focused on the situation in which there are a small number of sources and relays and a destination. In this paper, cooperative relay networks with large numbers of nodes are analyzed, and in particular the asymptotic performance improvement of cooperative transmission over direction transmission and relay transmission is analyzed using random matrix theory. The key idea is to investigate the eigenvalue distributions related to channel capacity and to analyze the moments of this distribution in large wireless networks. A performance upper bound is derived, the performance in the low signal-to-noise-ratio regime is analyzed, and two approximations are obtained for high and low relay-to-destination link qualities, respectively. Finally, simulations are provided to validate the accuracy of the analytical results. The analysis in this paper provides important tools for the understanding and the design of large cooperative wireless networks.

  20. On full duplex Gaussian relay channels with self-interference

    KAUST Repository

    Behboodi, Arash

    2016-08-15

    Self interference (SI) in full duplex (FD) systems is the interference caused by the transmission stream on the reception stream. Being one of the main restrictive factors for performance of practical full duplex systems, however, not too much is known about its effect on the fundamental limits of relaying systems. In this work, we consider the full duplex three-node relay channel with SI where SI is modeled as an additive Gaussian noise whose variance is dependent on instantaneous input power. The classical achievable rates and upper bounds for the single three-node relay channel no longer apply due to the structure of SI. Achievable rates for Decode-and-Forward (DF) and Compress-and-Forward (CF) and upper bounds on the capacity are derived assuming Gaussian inputs and SI. The deterministic model is also introduced and its capacity is characterized. The optimal joint source-relay distributions is discussed. Numerical results are provided comparing the achievable rates and upper bound. © 2016 IEEE.

  1. Staged-Fault Testing of Distance Protection Relay Settings

    Science.gov (United States)

    Havelka, J.; Malarić, R.; Frlan, K.

    2012-01-01

    In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.

  2. 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...

  3. 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.

  4. 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.

  5. Optimal Coordination of Distance and Directional Overcurrent Relays Considering Different Network Topologies

    Directory of Open Access Journals (Sweden)

    Y. Damchi

    2015-09-01

    Full Text Available 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 determined based on a main network topology which may result in mis-coordination of relays when changes occur in the network topology. In the proposed method, in order to have a robust coordination, network topology changes are taken into account in the coordination problem. In the new formulation, coordination constraints for different network topologies are added to those of the main topology. A complex nonlinear optimization problem is derived to find the desirable relay settings. Then, the problem is solved using hybridized genetic algorithm (GA with linear programming (LP method (HGA. The proposed method is evaluated using the IEEE 14-bus test system. According to the results, a feasible and robust solution is obtained for D&DOCRs coordination while all constraints, which are due to different network topologies, are satisfied.

  6. Technique for determination of the time constant for relay radioisotope instruments

    International Nuclear Information System (INIS)

    Gol'din, M.L.; Shestialtynov, V.K.

    1981-01-01

    A technique for calculating time constant of a gamma relay used in radio isotope automatics is suggested. It is shown that the time constant of a radioisotope relay device (RRD) mainly depends on parameters of the intergrating circuit ratemeter. Considering the ratemeter as a real communication channel with a limited transmission band, the equation for the active front duration at a ratemeter outlet when applying abrupt voltage to its inlet is obtained. From the complex transmission function of a ratemeter the upper boundary cyclic transmission frequency the substitution of which in the equation of the active front durationg ives the RRD time constant is determined. On the example of calculating the ratemeter for the GR-6 gamma relay a satisfactory coincidence of calculational results with the certificate data is shown [ru

  7. Secret-Key-Aided Scheme for Securing Untrusted DF Relaying Networks

    KAUST Repository

    Shafie, Ahmed El

    2017-06-12

    This paper proposes a new scheme to secure the transmissions in an untrusted decode-and-forward (DF) relaying network. A legitimate source node, Alice, sends her data to a legitimate destination node, Bob, with the aid of an untrusted DF relay node, Charlie. To secure the transmissions from Charlie during relaying time slots, each data codeword is secured using a secret-key codeword that has been previously shared between Alice and Bob during the perfectly secured time slots (i.e., when the channel secrecy rate is positive). The secret-key bits exchanged between Alice and Bob are stored in a finite-length buffer and are used to secure data transmission whenever needed. We model the secret-key buffer as a queueing system and analyze its Markov chain. Our numerical results show the gains of our proposed scheme relative to benchmarks. Moreover, the proposed scheme achieves an upper bound on the secure throughput.

  8. Secret-Key-Aided Scheme for Securing Untrusted DF Relaying Networks

    KAUST Repository

    Shafie, Ahmed El; Salem, Ahmed Sultan; Mabrouk, Asma; Tourki, Kamel; Al-Dhahir, Naofal

    2017-01-01

    This paper proposes a new scheme to secure the transmissions in an untrusted decode-and-forward (DF) relaying network. A legitimate source node, Alice, sends her data to a legitimate destination node, Bob, with the aid of an untrusted DF relay node, Charlie. To secure the transmissions from Charlie during relaying time slots, each data codeword is secured using a secret-key codeword that has been previously shared between Alice and Bob during the perfectly secured time slots (i.e., when the channel secrecy rate is positive). The secret-key bits exchanged between Alice and Bob are stored in a finite-length buffer and are used to secure data transmission whenever needed. We model the secret-key buffer as a queueing system and analyze its Markov chain. Our numerical results show the gains of our proposed scheme relative to benchmarks. Moreover, the proposed scheme achieves an upper bound on the secure throughput.

  9. 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

  10. 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.

  11. Optimal coordination of distance and over-current relays in series compensated systems based on MAPSO

    International Nuclear Information System (INIS)

    Moravej, Zahra; Jazaeri, Mostafa; Gholamzadeh, Mehdi

    2012-01-01

    Highlight: ► Optimal coordination problem between distance relays and Directional Over-Current Relays (DOCRs) is studied. ► A new problem formulation for both uncompensated and series compensated system is proposed. ► In order to solve the coordination problem a Modified Adaptive Particle Swarm Optimization (MAPSO) is employed. ► The optimum results are found in both uncompensated and series compensated systems. - Abstract: In this paper, a novel problem formulation for optimal coordination between distance relays and Directional Over-Current Relays (DOCRs) in series compensated systems is proposed. The integration of the series capacitor (SC) into the transmission line makes the coordination problem more complex. The main contribution of this paper is a new systematic method for computing the optimal second zone timing of distance relays and optimal settings of DOCRs, in series compensated and uncompensated transmission systems, which have a combined protection scheme with DOCRs and distance relays. In order to solve this coordination problem, which is a nonlinear and non-convex problem, a Modified Adaptive Particle Swarm Optimization (MAPSO) is employed. The new proposed method is supported by obtained results from a typical test case and a real power system network.

  12. Exploiting Outage and Error Probability of Cooperative Incremental Relaying in Underwater Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hina Nasir

    2016-07-01

    Full Text Available This paper embeds a bi-fold contribution for Underwater Wireless Sensor Networks (UWSNs; performance analysis of incremental relaying in terms of outage and error probability, and based on the analysis proposition of two new cooperative routing protocols. Subject to the first contribution, a three step procedure is carried out; a system model is presented, the number of available relays are determined, and based on cooperative incremental retransmission methodology, closed-form expressions for outage and error probability are derived. Subject to the second contribution, Adaptive Cooperation in Energy (ACE efficient depth based routing and Enhanced-ACE (E-ACE are presented. In the proposed model, feedback mechanism indicates success or failure of data transmission. If direct transmission is successful, there is no need for relaying by cooperative relay nodes. In case of failure, all the available relays retransmit the data one by one till the desired signal quality is achieved at destination. Simulation results show that the ACE and E-ACE significantly improves network performance, i.e., throughput, when compared with other incremental relaying protocols like Cooperative Automatic Repeat reQuest (CARQ. E-ACE and ACE achieve 69% and 63% more throughput respectively as compared to CARQ in hard underwater environment.

  13. 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.

  14. On network coding and modulation mapping for three-phase bidirectional relaying

    KAUST Repository

    Chang, Ronald Y.; Lin, Sian Jheng; Chung, Wei-Ho

    2015-01-01

    © 2015 IEEE. In this paper, we consider the network coding (NC) enabled three-phase protocol for information exchange between two users in a wireless two-way (bidirectional) relay network. Modulo-based (nonbinary) and XOR-based (binary) NC schemes are considered as information mixture schemes at the relay while all transmissions adopt pulse amplitude modulation (PAM). We first obtain the optimal constellation mapping at the relay that maximizes the decoding performance at the users for each NC scheme. Then, we compare the two NC schemes, each in conjunction with the optimal constellation mapping at the relay, in different conditions. Our results demonstrate that, in the low SNR regime, binary NC outperforms nonbinary NC with 4-PAM, while they have mixed performance with 8-PAM. This observation applies to quadrature amplitude modulation (QAM) composed of two parallel PAMs.

  15. On network coding and modulation mapping for three-phase bidirectional relaying

    KAUST Repository

    Chang, Ronald Y.

    2015-12-03

    © 2015 IEEE. In this paper, we consider the network coding (NC) enabled three-phase protocol for information exchange between two users in a wireless two-way (bidirectional) relay network. Modulo-based (nonbinary) and XOR-based (binary) NC schemes are considered as information mixture schemes at the relay while all transmissions adopt pulse amplitude modulation (PAM). We first obtain the optimal constellation mapping at the relay that maximizes the decoding performance at the users for each NC scheme. Then, we compare the two NC schemes, each in conjunction with the optimal constellation mapping at the relay, in different conditions. Our results demonstrate that, in the low SNR regime, binary NC outperforms nonbinary NC with 4-PAM, while they have mixed performance with 8-PAM. This observation applies to quadrature amplitude modulation (QAM) composed of two parallel PAMs.

  16. Central composite design with the help of multivariate curve resolution in loadability optimization of RP-HPLC to scale-up a binary mixture.

    Science.gov (United States)

    Taheri, Mohammadreza; Moazeni-Pourasil, Roudabeh Sadat; Sheikh-Olia-Lavasani, Majid; Karami, Ahmad; Ghassempour, Alireza

    2016-03-01

    Chromatographic method development for preparative targets is a time-consuming and subjective process. This can be particularly problematic because of the use of valuable samples for isolation and the large consumption of solvents in preparative scale. These processes could be improved by using statistical computations to save time, solvent and experimental efforts. Thus, contributed by ESI-MS, after applying DryLab software to gain an overview of the most effective parameters in separation of synthesized celecoxib and its co-eluted compounds, design of experiment software that relies on multivariate modeling as a chemometric approach was used to predict the optimized touching-band overloading conditions by objective functions according to the relationship between selectivity and stationary phase properties. The loadability of the method was investigated on the analytical and semi-preparative scales, and the performance of this chemometric approach was approved by peak shapes beside recovery and purity of products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The Case for Deep Space Telecommunications Relay Stations

    Science.gov (United States)

    Chandler, Charles W.; Miranda, Felix A. (Technical Monitor)

    2004-01-01

    Each future mission to Jupiter and beyond must carry the traditional suite of telecommunications systems for command and control and for mission data transmission to earth. The telecommunications hardware includes the large antenna and the high-power transmitters that enable the communications link. Yet future spacecraft will be scaled down from the hallmark missions of Galileo and Cassini to Jupiter and Saturn, respectively. This implies that a higher percentage of the spacecraft weight and power must be dedicated to telecommunications system. The following analysis quantifies this impact to future missions and then explores the merits of an alternative approach using deep space relay stations for the link back to earth. It will be demonstrated that a telecommunications relay satellite would reduce S/C telecommunications weight and power sufficiently to add one to two more instruments.

  18. On the performance of hybrid-ARQ with incremental redundancy and with code combining over relay channels

    KAUST Repository

    Chelli, Ali

    2013-08-01

    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). The relay overhears the transmitted messages over the different HARQ rounds and tries to decode the data packet. In case of successful decoding at the relay, both the relay and the source cooperate to transmit the message to the destination. The channel realizations are independent for different HARQ rounds. We assume that the transmitter has no channel state information (CSI). Under such conditions, power and rate adaptation are not possible. To overcome this problem, HARQ allows the implicit adaptation of the transmission rate to the channel conditions by the use of feedback. There are two major HARQ techniques, namely HARQ with incremental redundancy (IR) and HARQ with code combining (CC). We investigate the performance of HARQ-IR and HARQ-CC over a relay channel from an information theoretic perspective. Analytical expressions are derived for the information outage probability, the average number of transmissions, and the average transmission rate. We illustrate through our investigation the benefit of relaying. We also compare the performance of HARQ-IR and HARQ-CC and show that HARQ-IR outperforms HARQ-CC. © 2013 IEEE.

  19. 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.

  20. 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.

  1. Reliability Analysis of Differential Relay as Main Protection Transformer Using Fuzzy Logic Algorithm

    Science.gov (United States)

    Mulyadi, Y.; Sucita, T.; Sumarto; Alpani, M.

    2018-02-01

    Electricity supply demand is increasing every year. It makes PT. PLN (Persero) is required to provide optimal customer service and satisfaction. Optimal service depends on the performance of the equipment of the power system owned, especially the transformer. Power transformer is an electrical equipment that transforms electricity from high voltage to low voltage or vice versa. However, in the electrical power system, is inseparable from interference included in the transformer. But, the disturbance can be minimized by the protection system. The main protection transformer is differential relays. Differential relays working system using Kirchoff law where inflows equal outflows. If there are excessive currents that interfere then the relays will work. But, the relay can also experience decreased performance. Therefore, this final project aims to analyze the reliability of the differential relay on the transformer in three different substations. Referring to the standard applied by the transmission line protection officer, the differential relay shall have slope characteristics of 30% in the first slope and 80% in the second slope when using two slopes and 80% when using one slope with an instant time and the corresponding ratio. So, the results obtained on the Siemens differential release have a reliable slope characteristic with a value of 30 on the fuzzy logic system. In a while, ABB a differential relay is only 80% reliable because two experiments are not reliable. For the time, all the differential relays are instant with a value of 0.06 on the fuzzy logic system. For ratios, the differential relays ABB have a better value than others brand with a value of 151 on the fuzzy logic system.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. 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

  7. Full-diversity partial interference cancellation for multi-user wireless relaying networks

    KAUST Repository

    El Astal, M. T O

    2013-12-01

    We focus on the uplink channel of multi-user wireless relaying networks in a coverage extension scenario. The network consists of two users, a single half duplex (HD) relay and a destination, all equipped with multiple antennas. Perfect channel state information (CSI) is assumed to be available exclusively at the receiving nodes (i.e., the relay and the destination) while the users are assumed to be completely blind. The communication through the considered network takes place over two phases. During the first phase, both users send their information concurrently to the relay. The second phase consists of decoding the received data and forwarding it simultaneously to the destination. A transmission scheme that achieves full-diversity under partial interference cancellation (PIC) group decoding is proposed. Unlike many existing schemes, it allows the concurrent transmission in both phases while achieving the full-diversity gain of full time division multiple access (TDMA) transmission regardless of the number of antennas at each node. Numerical comparison with existing schemes in the literature is provided to corroborate our theoretical claims. It is found that our interference cancellation (IC) scheme clearly outperforms existing schemes at the expense of an affordable increase in decoding complexity at both of the relay and destination. © 2013 IEEE.

  8. Full-diversity partial interference cancellation for multi-user wireless relaying networks

    KAUST Repository

    El Astal, M. T O; Ismail, Amr; Alouini, Mohamed-Slim; Olivier, Jan Corné

    2013-01-01

    We focus on the uplink channel of multi-user wireless relaying networks in a coverage extension scenario. The network consists of two users, a single half duplex (HD) relay and a destination, all equipped with multiple antennas. Perfect channel state information (CSI) is assumed to be available exclusively at the receiving nodes (i.e., the relay and the destination) while the users are assumed to be completely blind. The communication through the considered network takes place over two phases. During the first phase, both users send their information concurrently to the relay. The second phase consists of decoding the received data and forwarding it simultaneously to the destination. A transmission scheme that achieves full-diversity under partial interference cancellation (PIC) group decoding is proposed. Unlike many existing schemes, it allows the concurrent transmission in both phases while achieving the full-diversity gain of full time division multiple access (TDMA) transmission regardless of the number of antennas at each node. Numerical comparison with existing schemes in the literature is provided to corroborate our theoretical claims. It is found that our interference cancellation (IC) scheme clearly outperforms existing schemes at the expense of an affordable increase in decoding complexity at both of the relay and destination. © 2013 IEEE.

  9. 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.

  10. 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.

  11. 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.

  12. 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.)

  13. 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

  14. First multivendor scheme in CFE to protection of 400 kV transmission line, using optical TC's, digital relays and bus IEC 61850-9-2; Primer esquema multivendedor en CFE para proteccion de linea de transmision de 400 kV, utilizando TC's opticos, relevadores digitales y bus IEC 61850-9-2

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Colon, V.R; Rasgado, J.P [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Lara C, H; Melendez, C; Juarez, N [Subdireccion de Transmision, Comision Federal de Electricidad (Mexico)

    2013-03-15

    This paper presents the details of design, installation and putting into service in the Comision Federal de Electricidad (CFE), of the first multi-vendor scheme that exists in the world, for the protection of a 400kV transmission line, which uses optical current transformers and digital relays IEC 61850-9-2. This system arises as a pilot project of the Subdireccion de Transmision of the CFE with the Instituto de Investigaciones Electricas (IIE). To ensure success in the implementation of the protection scheme, CFE joined a team coordinated by the Instituto de Investigaciones Electricas (IIE)involving nine international companies and a university. Pilot protection scheme is in operation under continuous monitoring, in one of the transmission lines of CFE that interconnect Manuel Moreno Torres with El Juile substations. The construction features, the challenges that were overcome and the first results obtained in operation are presented below. [Spanish] Este articulo presenta los detalles del diseno, instalacion y puesta en servicio en la Comision Federal de Electricidad (CFE) del primer esquema multivendedor que existe en el mundo, para la proteccion de una linea de transmision de 400kV, que utiliza transformadores de corriente opticos y relevadores digitales IEC 61850-9-2. Este sistema surge como un proyecto piloto de la Subdireccion de Transmision de la CFE con el Instituto de Investigaciones Electricas (IIE). Para asegurar el exito en la implementacion del esquema de proteccion, la CFE integro un equipo de trabajo coordinado por el Instituto de Investigaciones Electricas (IIE) en el que participaron 9 empresas internacionales y una universidad. El esquema de proteccion piloto, se encuentra en operacion bajo monitoreo continuo, en una de las lineas de transmision de la CFE que interconecta las subestaciones de Manuel Moreno Torres y El Juile. Las caracteristicas de construccion, los retos que fueron vencidos y los primeros resultados obtenidos en su operacion se

  15. 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...

  16. 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

  17. Dynamic temperature estimation and real time emergency rating of transmission cables

    DEFF Research Database (Denmark)

    Olsen, R. S.; Holboll, J.; Gudmundsdottir, Unnur Stella

    2012-01-01

    enables real time emergency ratings, such that the transmission system operator can make well-founded decisions during faults. Hereunder is included the capability of producing high resolution loadability vs. time schedules within few minutes, such that the TSO can safely control the system.......). It is found that the calculated temperature estimations are fairly accurate — within 1.5oC of the finite element method (FEM) simulation to which it is compared — both when looking at the temperature profile (time dependent) and the temperature distribution (geometric dependent). The methodology moreover...

  18. Effect Evaluation of Fault Resistance on the Operating Behavior of a Distance Relay

    Directory of Open Access Journals (Sweden)

    K. H. Le

    2018-06-01

    Full Text Available This paper presents an application of a certain distance protection relay with a quadrilateral characteristic approach for the protection of the 110kV Duy Xuyen - Thang Binh transmission line in Vietnam using measured data from one terminal line. We propose the building process of a Matlab Simulink model for this relay that combines fault detection and classification block, apparent impedance calculation block for all types of faults and a trip logic block of three zone protection coordination. The proposed relay model is further tested using various fault scenarios on the transmission line. It is important to assess what happened, the actual conditions, the causes of mal-operation etc. Detailed explanation and results indicate that the proposed model behavior will help users to perform tests which correctly simulate real-world conditions besides that it properly interprets test results and troubleshoot distance function problems when results are not as expected.

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Outage analysis for underlay cognitive networks using incremental regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-02-01

    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 the quality of service (QoS) of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. Analysis is conducted for two schemes, referred to as the channel-state information (CSI)-based and fault-tolerant schemes, respectively, where different amounts of CSI were considered. We first provide the exact cumulative distribution function (cdf) of the received signal-to-noise ratio (SNR) over each hop with colocated relays. Then, the cdf\\'s are used to determine a very accurate closed-form expression for the outage probability for a transmission rate $R$. In a high-SNR region, a floor of the secondary outage probability occurs, and we derive its corresponding expression. We validate our analysis by showing that the simulation results coincide with our analytical results in Rayleigh fading channels. © 1967-2012 IEEE.

  5. Outage Analysis and Optimization of SWIPT in Network-Coded Two-Way Relay Networks

    Directory of Open Access Journals (Sweden)

    Ruihong Jiang

    2017-01-01

    Full Text Available This paper investigates the outage performance of simultaneous wireless information and power transfer (SWIPT in network-coded two-way relay systems, where a relay first harvests energy from the signals transmitted by two sources and then uses the harvested energy to forward the received information to the two sources. We consider two transmission protocols, power splitting two-way relay (PS-TWR and time switching two-way relay (TS-TWR protocols. We present two explicit expressions for the system outage probability of the two protocols and further derive approximate expressions for them in high and low SNR cases. To explore the system performance limits, two optimization problems are formulated to minimize the system outage probability. Since the problems are nonconvex and have no known solution methods, a genetic algorithm- (GA- based algorithm is designed. Numerical and simulation results validate our theoretical analysis. It is shown that, by jointly optimizing the time assignment and SWIPT receiver parameters, a great performance gain can be achieved for both PS-TWR and TS-TWR. Moreover, the optimized PS-TWR always outperforms the optimized TS-TWR in terms of outage performance. Additionally, the effects of parameters including relay location and transmit powers are also discussed, which provide some insights for the SWIPT-enabled two-way relay networks.

  6. Joint Subcarrier Pairing and Resource Allocation for Cognitive Network and Adaptive Relaying Strategy

    KAUST Repository

    Soury, Hamza

    2012-05-01

    Recent measurements show that the spectrum is under-utilized by licensed users in wireless communication. Cognitive radio (CR) has been proposed as a suitable solution to manage the inefficient usage of the spectrum and increase coverage area of wireless networks. The concept is based on allowing a group of secondary users (SUs) to share the unused radio spectrum originally owned by the primary user (PUs). The operation of CR should not cause harmful interference to the PUs. In the other hand, relayed transmission increases the coverage and achievable capacity of communication systems and in particular in CR systems. In fact there are many types of cooperative communications, however the two main ones are decode-and-forward (DAF) and amplify-and-forward (AAF). Adaptive relaying scheme is a relaying technique by which the benefits of the amplifying or decode and forward techniques can be achieved by switching the forwarding technique according to the quality of the signal. In this dissertation, we investigate the power allocation for an adaptive relaying protocol (ARP) scheme in cognitive system by maximizing the end-to-end rate and searching the best carriers pairing distribution. The optimization problem is under the interference and power budget constraints. The simulation results confirm the efficiency of the proposed adaptive relaying protocol in comparison to other relaying techniques, and the consequence of the choice of the pairing strategy.

  7. Distributed cognitive two-way relay beamformer designs under perfect and imperfect CSI

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2011-09-01

    In this paper, we present distributed two-way relay beamformer designs for a cognitive radio network (CRN) in which a pair of cognitive (or secondary) transceiver nodes communicate with each other assisted by a set of cognitive two-way relay nodes. 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. First, we consider relay beamformer designs assuming the availability of perfect channel state information (CSI). For this case, a mean-square error (MSE)-constrained beamformer that minimizes the total relay transmit power, and an MSE-balancing beamformer with a constraint on the total relay transmit power are proposed. Next, we consider relay beamformer designs assuming that the available CSI is imperfect. For this case too, we consider the same problems as those in the case of perfect CSI, and propose beamformer designs that are robust to the errors in the CSI. We show that the proposed designs can be reformulated as convex optimization problems that can be solved efficiently. Through numerical simulations, we illustrate the performance of the proposed designs. © 2011 IEEE.

  8. 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.

  9. 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

  10. 77 FR 14773 - Sunshine Act Meeting

    Science.gov (United States)

    2012-03-13

    ... Standards. E-6 RM11-16-000 Transmission Relay Loadability Reliability Standard. E-7 RM11-20-000 Automatic...-7-000 Magellan Pipeline Company, L.P. Hydro H-1 P-14107-000 Lock+Hydro Friends Fund I. H-2 P-739-026...

  11. 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.

  12. 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.

  13. 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.

  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. Improving Spectral Capacity and Wireless Network Coverage by Cognitive Radio Technology and Relay Nodes in Cellular Systems

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge

    2008-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context have been presented and discussed in this paper. Ideas to improve the wireless transmission by orthogonal OFDM-based communication and to increase the...... the coverage of cellular systems by future wireless networks, relay channels, relay stations and collaborate radio have been presented as well. A revised hierarchical deployment of the future wireless and wired networks are shortly discussed....

  16. Comparison of Beam-Forming and Relaying in Sparse Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mikuláš Krebs

    2015-12-01

    Full Text Available This study focuses on the differences in power consumption between beam-forming and relaying data transmission methods in a sparse wireless ad-hoc network. These two methods are observed for the same parameters using an identical network topology in a simulation programme that was developed as a part of this study.

  17. Relay-assisted Network Coding Multicast in the Presence of Neighbours

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Pahlevani, Peyman

    2015-01-01

    We study the problem of minimizing the cost of packet transmission from a source to two receivers with the help of a relay and using network coding in wireless mesh networks consisting of many active neighbours sharing the same channel. The cost minimization problem is modeled as a Markov Decisio...

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

    KAUST Repository

    Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim

    2018-01-01

    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

  19. Beamforming-Based Physical Layer Network Coding for Non-Regenerative Multi-Way Relaying

    Directory of Open Access Journals (Sweden)

    Klein Anja

    2010-01-01

    Full Text Available We propose non-regenerative multi-way relaying where a half-duplex multi-antenna relay station (RS assists multiple single-antenna nodes to communicate with each other. The required number of communication phases is equal to the number of the nodes, N. There are only one multiple-access phase, where the nodes transmit simultaneously to the RS, and broadcast (BC phases. Two transmission methods for the BC phases are proposed, namely, multiplexing transmission and analog network coded transmission. The latter is a cooperation method between the RS and the nodes to manage the interference in the network. Assuming that perfect channel state information is available, the RS performs transceive beamforming to the received signals and transmits simultaneously to all nodes in each BC phase. We address the optimum transceive beamforming maximising the sum rate of non-regenerative multi-way relaying. Due to the nonconvexity of the optimization problem, we propose suboptimum but practical signal processing schemes. For multiplexing transmission, we propose suboptimum schemes based on zero forcing, minimising the mean square error, and maximising the signal to noise ratio. For analog network coded transmission, we propose suboptimum schemes based on matched filtering and semidefinite relaxation of maximising the minimum signal to noise ratio. It is shown that analog network coded transmission outperforms multiplexing transmission.

  20. Broadcast Reserved Opportunity Assisted Diversity Relaying Scheme and Its Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Xia Chen

    2008-05-01

    Full Text Available Relay-based transmission can over the benefits in terms of coverage extension as well as throughput improvement if compared to conventional direct transmission. In a relay enhanced cellular (REC network, where multiple mobile terminals act as relaying nodes (RNs, multiuser diversity gain can be exploited. We propose an efficient relaying scheme, referred to as Broadcast Reserved Opportunity Assisted Diversity (BROAD for the REC networks. Unlike the conventional Induced Multiuser Diversity Relaying (IMDR scheme, our scheme acquires channel quality information (CQI in which the destined node (DN sends pilots on a reserved radio resource. The BROAD scheme can significantly decrease the signaling overhead among the mobile RNs while achieving the same multiuser diversity as the conventional IMDR scheme. In addition, an alternative version of the BROAD scheme, named as A-BROAD scheme, is proposed also, in which the candidate RN(s feed back partial or full CQI to the base station (BS for further scheduling purpose. The A-BROAD scheme achieves a higher throughput than the BROAD scheme at the cost of extra signalling overhead. The theoretical analysis given in this paper demonstrates the feasibility of the schemes in terms of their multiuser diversity gains in a REC network.

  1. 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.

  2. 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.

  3. Optimal Coordination of Directional Overcurrent Relays Using PSO-TVAC Considering Series Compensation

    Directory of Open Access Journals (Sweden)

    Nabil Mancer

    2015-01-01

    Full Text Available The integration of system compensation such as Series Compensator (SC into the transmission line makes the coordination of directional overcurrent in a practical power system important and complex. This article presents an efficient variant of Particle Swarm Optimization (PSO algorithm based on Time-Varying Acceleration Coefficients (PSO-TVAC for optimal coordination of directional overcurrent relays (DOCRs considering the integration of series compensation. Simulation results are compared to other methods to confirm the efficiency of the proposed variant PSO in solving the optimal coordination of directional overcurrent relay in the presence of series compensation.

  4. Impact of Apparent Reactance Injected by TCSR on Distance Relay in Presence Phase to Earth Fault

    Directory of Open Access Journals (Sweden)

    Mohamed Zellagui

    2013-01-01

    Full Text Available This research paper presents the impact study of apparent reactance injected by series Flexible AC Transmission System (FACTS i.e. Thyristor Controlled Series Reactor (TCSR on the measured impedance of a 400 kV single electrical transmission line in the presence of phase to earth fault with fault resistance. The study deals with an electrical transmission line of Eastern Algerian transmission networks at Group Sonelgaz (Algerian Company of Electrical compensated by TCSR connected at midpoint of the transmission line. This compensator used to inject voltage and reactive power is controlled by TCSR. The simulations results investigate the three impacts of the apparent reactance injected by TCSR (XTCSR on transmission line protected by distance relay protection. The impacts concern the active and reactive power, the line impedance (reactance and resistance, and the short circuit parameters (symmetrical currents, line currents, symmetrical voltages and line voltages as well as the measured impedance by relay (resistance and reactance in the presence of earth fault These impacts are investigated in order to improve the performances of distance relay protection. More the impact of XTCSR by three TCSR for cases studies is presented.

  5. Enhancement of solubility and therapeutic potential of poorly soluble lovastatin by SMEDDS formulation adsorbed on directly compressed spray dried magnesium aluminometasilicate liquid loadable tablets: A study in diet induced hyperlipidemic rabbits

    Directory of Open Access Journals (Sweden)

    Mohd Javed Qureshi

    2015-02-01

    Full Text Available The aim of present study was to formulate and evaluate a self-microemulsifying drug delivery systems (SMEDDS containing lovastatin and to further explore the ability of porous Neusilin® US2 tablet as a solid carrier for SMEDDS. SMEDDS formulations of varying proportions of peceol, cremophor RH 40 and transcutol-P were selected and subjected to in-vitro evaluation, including dispersibility studies, droplet size, zeta potential measurement and release studies. The results indicated that the drug release profile of lovastatin from SMEDDS formulations was statistically significantly higher (p-value < 0.05 than the plain lovastatin powder. Thermodynamic stability studies also confirmed the stability of the prepared SMEDDS formulations. The optimized formulation, which consists of 12% of peceol, 44% of cremophor RH 40, and 44% of transcutol-P was loaded into directly compressed liquid loadable tablet of Neusilin® US2 by simple adsorption method. In order to determine the ability of Neusilin® US2 as a suitable carrier pharmacodynamics study were also carried out in healthy diet induced hyperlipidemic rabbits. Animals were administered with both liquid SMEDDS and solid SMEDDS as well. From the results obtained, Neusilin® was found to be a suitable carrier for SMEDDS and was equally effective in reducing the elevated lipid profile. In conclusion, liquid loadable tablet (LLT is predicted to be a promising technique to deliver a liquid formulation in solid state.

  6. 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)

  7. 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.

  8. 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.

  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. 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.

  12. 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.

  13. 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

  14. 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...

  15. 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.

  16. Performance analysis of AF cooperative systems with HPA nonlinearity in semi-blind relays

    KAUST Repository

    Qi, Jian; Aï ssa, Sonia; Alouini, Mohamed-Slim

    2012-01-01

    In this paper, dual-hop amplify-and-forward (AF) cooperative systems in the presence of high-power amplifier (HPA) nonlinearity at semi-blind relays, are investigated. Based on the modified AF cooperative system model taking into account the HPA nonlinearity, the expression for the output signal-to-noise ratio (SNR) at the destination node is derived, where the interference due to both the AF relaying mechanism and the HPA nonlinearity is characterized. The performance of the AF cooperative system under study is evaluated in terms of average symbol error probability (SEP), which is derived using the moment-generating function (MGF) approach, considering transmissions over Nakagami-m fading channels. Numerical results are provided and show the effects of some system parameters, such as the HPA parameters, numbers of relays, quadrature amplitude modulation (QAM) order, Nakagami parameters, on performance. © 2012 IEEE.

  17. Joint Network Coding and Opportunistic Scheduling for the Bidirectional Relay Channel

    KAUST Repository

    Shaqfeh, Mohammad

    2013-05-27

    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.

  18. On the Coded Packet Relay Network in the Presence of Neighbors

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani

    2014-01-01

    This paper studies the problem of optimal use of a relay for reducing the transmission time of data packets from a source to a destination using network coding. More importantly, we address an effect that is typically overlooked in previous studies: the presence of active transmitting nodes...... in the neighborhood of such devices, which is typical in wireless mesh networks. We show that in systems with a fair medium access control mechanism (MAC), the use of a relay in a crowded medium brings forth considerable and unforeseen improvements, including up to 3.5x gains in terms of throughput compared to using...... only the direct link in some of our examples, and a considerable extension of the operating region where using a relay is beneficial. The problem is formulated as a Markov Decision Process (MDP) and numerical results are provided comparing simple, close–to–optimal heuristics to the optimal scheme....

  19. Analysis and Solution for Operations of Overcurrent Relay in Wind Power System

    Directory of Open Access Journals (Sweden)

    Yeonho Ok

    2016-06-01

    Full Text Available Wind power systems are being integrated increasingly into the power grid because of their large capacity and easy access to the transmission grid. The reliability of wind power plants is very important and the elimination of protective relay’s malfunctions is essential to the mitigation of power quality problems due to the frequent starts and stops of high capacity wind generators. In this study, the problem of frequent false operations of the protective relays are analyzed using real data as line voltages, line currents, and wind speed. A new re-coordination of the overcurrent relay (OCR based on the wind speed is proposed to avoid frequent operations of relays and tested for a grid-connected wind farm. This study verifies that the false actions by the OCRs that are not accompanied by actual electrical faults in the power grid or wind power system can be solved by the appropriate re-coordination of the OCR.

  20. Performance analysis of AF cooperative systems with HPA nonlinearity in semi-blind relays

    KAUST Repository

    Qi, Jian

    2012-12-01

    In this paper, dual-hop amplify-and-forward (AF) cooperative systems in the presence of high-power amplifier (HPA) nonlinearity at semi-blind relays, are investigated. Based on the modified AF cooperative system model taking into account the HPA nonlinearity, the expression for the output signal-to-noise ratio (SNR) at the destination node is derived, where the interference due to both the AF relaying mechanism and the HPA nonlinearity is characterized. The performance of the AF cooperative system under study is evaluated in terms of average symbol error probability (SEP), which is derived using the moment-generating function (MGF) approach, considering transmissions over Nakagami-m fading channels. Numerical results are provided and show the effects of some system parameters, such as the HPA parameters, numbers of relays, quadrature amplitude modulation (QAM) order, Nakagami parameters, on performance. © 2012 IEEE.

  1. Energy efficient design for MIMO two-way AF multiple relay networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2014-04-01

    This paper studies the energy efficient transmission and the power allocation problem for multiple two-way relay networks equipped with multi-input multi-output antennas where each relay employs an amplify-and-forward strategy. The goal is to minimize the total power consumption without degrading the quality of service of the terminals. In our analysis, we start by deriving closed-form expressions of the optimal powers allocated to terminals. We then employ a strong optimization tool based on the particle swarm optimization technique to find the optimal power allocated at each relay antenna. Our numerical results illustrate the performance of the proposed scheme and show that it achieves a sub-optimal solution very close to the optimal one.

  2. 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.

  3. 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.

  4. Joint Network Coding and Opportunistic Scheduling for the Bidirectional Relay Channel

    KAUST Repository

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

    2013-01-01

    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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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 ...

  10. 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.

  11. On Amplify-and-Forward Relaying Over Hyper-Rayleigh Fading Channels

    Directory of Open Access Journals (Sweden)

    S. H. Alvi

    2014-12-01

    Full Text Available Relayed transmission holds promise for the next generation of wireless communication systems due to the performance gains it can provide over non-cooperative systems. Recently hyper-Rayleigh fading, which represents fading conditions more severe than Rayleigh fading, has received attention in the context of many practical communication scenarios. Though power allocation for Amplify-and-Forward (AF relaying networks has been studied in the literature, a theoretical analysis of the power allocation problem for hyper-Rayleigh fading channels is a novel contribution of this work. We develop an optimal power allocation (OPA strategy for a dual-hop AF relaying network in which the relay-destination link experiences hyper-Rayleigh fading. A new closed-form expression for the average signal-to-noise ratio (SNR at destination is derived and it is shown to provide a new upper-bound on the average SNR at destination, which outperforms a previously proposed upper-bound based on the well-known harmonic-geometric mean inequality. An OPA across the source and relay nodes, subject to a sum-power constraint, is proposed and it is shown to provide measurable performance gains in average SNR and SNR outage at the destination relative to the case of equal power allocation.

  12. Cache Aided Decode-and-Forward Relaying Networks: From the Spatial View

    Directory of Open Access Journals (Sweden)

    Junjuan Xia

    2018-01-01

    Full Text Available We investigate cache technique from the spatial view and study its impact on the relaying networks. In particular, we consider a dual-hop relaying network, where decode-and-forward (DF relays can assist the data transmission from the source to the destination. In addition to the traditional dual-hop relaying, we also consider the cache from the spatial view, where the source can prestore the data among the memories of the nodes around the destination. For the DF relaying networks without and with cache, we study the system performance by deriving the analytical expressions of outage probability and symbol error rate (SER. We also derive the asymptotic outage probability and SER in the high regime of transmit power, from which we find the system diversity order can be rapidly increased by using cache and the system performance can be significantly improved. Simulation and numerical results are demonstrated to verify the proposed studies and find that the system power resources can be efficiently saved by using cache technique.

  13. Joint sub-carrier pairing and resource allocation for cognitive networks with adaptive relaying

    KAUST Repository

    Soury, Hamza; Bader, F.; Shaat, M.; Alouini, Mohamed-Slim

    2013-01-01

    Relayed transmission in a cognitive radio (CR) environment could be used to increase the coverage and capacity of communication system that benefits already from the efficient management of the spectrum developed by CR. Furthermore, there are many types of cooperative communications, including decode-and-forward (DAF) and amplify-and-forward (AAF). In this paper, these techniques are combined in an adaptive mode to benefit from its forwarding advantages; this mode is called adaptive relaying protocol (ARP). Moreover, this work focuses on the joint power allocation in a cognitive radio system in a cooperative mode that operates ARP in multi-carrier mode. The multi-carrier scenario is used in an orthogonal frequency division multiplexing (OFDM) mode, and the problem is formulated to maximize the end-to-end rate by searching the best power allocation at the transmitters. This work includes, besides the ARP model, a sub-carrier pairing strategy that allows the relays to switch to the best sub-carrier pairs to increase the throughput. The optimization problem is formulated and solved under the interference and power budget constraints using the sub-gradient algorithm. The simulation results confirm the efficiency of the proposed adaptive relaying protocol in comparison to other relaying techniques. The results show also the consequence of the choice of the pairing strategy. 2013 Stolojescu-Crisan and Isar; licensee Springer.

  14. Joint sub-carrier pairing and resource allocation for cognitive networks with adaptive relaying

    KAUST Repository

    Soury, Hamza

    2013-11-09

    Relayed transmission in a cognitive radio (CR) environment could be used to increase the coverage and capacity of communication system that benefits already from the efficient management of the spectrum developed by CR. Furthermore, there are many types of cooperative communications, including decode-and-forward (DAF) and amplify-and-forward (AAF). In this paper, these techniques are combined in an adaptive mode to benefit from its forwarding advantages; this mode is called adaptive relaying protocol (ARP). Moreover, this work focuses on the joint power allocation in a cognitive radio system in a cooperative mode that operates ARP in multi-carrier mode. The multi-carrier scenario is used in an orthogonal frequency division multiplexing (OFDM) mode, and the problem is formulated to maximize the end-to-end rate by searching the best power allocation at the transmitters. This work includes, besides the ARP model, a sub-carrier pairing strategy that allows the relays to switch to the best sub-carrier pairs to increase the throughput. The optimization problem is formulated and solved under the interference and power budget constraints using the sub-gradient algorithm. The simulation results confirm the efficiency of the proposed adaptive relaying protocol in comparison to other relaying techniques. The results show also the consequence of the choice of the pairing strategy. 2013 Stolojescu-Crisan and Isar; licensee Springer.

  15. Calibration and Evaluation of Fixed and Mobile Relay-Based System Level Simulator

    Directory of Open Access Journals (Sweden)

    Shahid Mumtaz

    2010-01-01

    Full Text Available Future wireless communication systems are expected to provide more stable and higher data rate transmissions in the whole OFDMA networks, but the mobile stations (MSs in the cell boundary experience poor spectral efficiency due to the path loss from the transmitting antenna and interference from adjacent cells. Therefore, satisfying QoS (Quality of Service requirements of each MS at the cell boundary has been an important issue. To resolve this spectral efficiency problem at the cell boundary, deploying relay stations has been actively considered. As multihop/relay has complex interactions between the routing and medium access control decisions, the extent to which analytical expressions can be used to explore its benefits is limited. Consequently, simulations tend to be the preferred way of assessing the performance of relays. In this paper, we evaluate the performance of relay-assisted OFDMA networks by means of system level simulator (SLS. We consistently observed that the throughput is increased and the outage is decreased in the relay-assisted OFDMA network, which is converted to range extension without any capacity penalty, for the realistic range of values of the propagation and other system parameters investigated.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Cross-Layer Design for Two-Way Relaying Networks with Multiple Antennas

    Directory of Open Access Journals (Sweden)

    zhuo wu

    2015-10-01

    Full Text Available In this paper, we developed a cross-layer design for two-way relaying (TWR networks with multiple antennas, where two single antenna source nodes exchange information with the aid of one multiple antenna relay node. The proposed cross-layer design considers adaptive modulation (AM and space-time block coding (STBC at the physical layer with an automatic repeat request (ARQ protocol at the data link layer, in order to maximize the spectral efficiency under specific delay and packet error ratio (PER constraints. An MMSE-interference cancellation (IC receiver is employed at the relay node, to remove the interference in the fist phase of the TWR transmission. The transmission mode is updated for each phase of the TWR transmission on a frame-by-frame basis, to match the time-varying channel conditions and exploit the system performance and throughput gain. Simulation results show that retransmission at the data link layer could alleviate rigorous error-control requirements at the physical layer, and thereby allows higher data transmission. As a result, cross-layer design helps to achieve considerable system spectral efficiency gain for TWR networks, compared to those without cross-layer design.

  9. 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.

  10. 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.

  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. 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.

  14. Protocol Design and Performance Analysis of Multiuser Mixed RF and Hybrid FSO/RF Relaying With Buffers

    KAUST Repository

    Al-Eryani, Yasser F.

    2018-03-07

    In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users\\' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay\\'s buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.

  15. 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.

  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. 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.

  18. 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

  19. 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 ...

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. Outage analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel

    2010-09-01

    In this paper, we investigate a dual-hop opportunistic decode-and-forward relaying scheme where the source may or not be able to communicate directly with the destination. We first derive statistics based on exact probability density function (PDF) of each hop. Then, the PDFs are used to determine closed-form outage probability expression for a transmission rate R. Furthermore, we evaluate the asymptotic outage performance and the diversity order is deduced. 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 under practical assumption of unbalanced hops. © 2010 IEEE.

  7. 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.

  8. 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 ...

  9. Strategies for improvement of spectrum capacity for WiMax cellular systems by Cognitive Radio Technology supported by Relay Stations

    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 improve the wireless transmission by orthogonal OFDM-based communication and to increase...... the coverage of cellular systems by relay stations will be presented as well.   ...

  10. Transmit Power Minimization and Base Station Planning for High-Speed Trains with Multiple Moving Relays in OFDMA Systems

    KAUST Repository

    Ghazzai, Hakim; Bouchoucha, Taha; Alsharoa, Ahmad; Yaacoub, Elias; Alouini, Mohamed-Slim; Al-Naffouri, Tareq Y.

    2016-01-01

    of the 3GPP Long Term Evolution-Advanced (LTE-A) and compare them with previously developed algorithms as well as with the direct transmission scenario. Our results also highlight the significant planning gain obtained thanks to the use of multiple relays

  11. On the performance of hybrid ARQ with incremental redundancy over amplify-and-forward dual-hop relay networks

    KAUST Repository

    Hadjtaieb, Amir

    2014-09-01

    In this paper, we consider a three node relay network comprising a source, a relay, and a destination. The source transmits the message to the destination using hybrid automatic repeat request (HARQ) with incremental redundancy (IR). The relay overhears the transmitted message, amplifies it using a variable gain amplifier, and then forwards the message to the destination. This latter combines both the source and the relay message and tries to decode the information. In case of decoding failure, the destination sends a negative acknowledgement. A new replica of the message containing new parity bits is then transmitted in the subsequent HARQ round. This process continues until successful decoding occurs at the destination or a maximum number M of rounds is reached. We study the performance of HARQ-IR over the considered relay channel from an information theoretic perspective. We derive for instance exact expressions and bounds for the information outage probability, the average number of transmissions, and the average transmission rate. The derived exact expressions are validated by Monte Carlo simulations.

  12. 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...

  13. 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...

  14. 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...

  15. 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

  16. 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.

  17. 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.

  18. 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...

  19. 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.

  20. 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…

  1. A Matrix-Based Proactive Data Relay Algorithm for Large Distributed Sensor Networks.

    Science.gov (United States)

    Xu, Yang; Hu, Xuemei; Hu, Haixiao; Liu, Ming

    2016-08-16

    In large-scale distributed sensor networks, sensed data is required to be relayed around the network so that one or few sensors can gather adequate relative data to produce high quality information for decision-making. In regards to very high energy-constraint sensor nodes, data transmission should be extremely economical. However, traditional data delivery protocols are potentially inefficient relaying unpredictable sensor readings for data fusion in large distributed networks for either overwhelming query transmissions or unnecessary data coverage. By building sensors' local model from their previously transmitted data in three matrixes, we have developed a novel energy-saving data relay algorithm, which allows sensors to proactively make broadcast decisions by using a neat matrix computation to provide balance between transmission and energy-saving. In addition, we designed a heuristic maintenance algorithm to efficiently update these three matrices. This can easily be deployed to large-scale mobile networks in which decisions of sensors are based on their local matrix models no matter how large the network is, and the local models of these sensors are updated constantly. Compared with some traditional approaches based on our simulations, the efficiency of this approach is manifested in uncertain environment. The results show that our approach is scalable and can effectively balance aggregating data with minimizing energy consumption.

  2. A Matrix-Based Proactive Data Relay Algorithm for Large Distributed Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yang Xu

    2016-08-01

    Full Text Available In large-scale distributed sensor networks, sensed data is required to be relayed around the network so that one or few sensors can gather adequate relative data to produce high quality information for decision-making. In regards to very high energy-constraint sensor nodes, data transmission should be extremely economical. However, traditional data delivery protocols are potentially inefficient relaying unpredictable sensor readings for data fusion in large distributed networks for either overwhelming query transmissions or unnecessary data coverage. By building sensors’ local model from their previously transmitted data in three matrixes, we have developed a novel energy-saving data relay algorithm, which allows sensors to proactively make broadcast decisions by using a neat matrix computation to provide balance between transmission and energy-saving. In addition, we designed a heuristic maintenance algorithm to efficiently update these three matrices. This can easily be deployed to large-scale mobile networks in which decisions of sensors are based on their local matrix models no matter how large the network is, and the local models of these sensors are updated constantly. Compared with some traditional approaches based on our simulations, the efficiency of this approach is manifested in uncertain environment. The results show that our approach is scalable and can effectively balance aggregating data with minimizing energy consumption.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. On the throughput of a relay-assisted cognitive radio MIMO channel with space alignment

    KAUST Repository

    Sboui, Lokman; Ghazzai, Hakim; Rezki, Zouheir; Alouini, Mohamed-Slim

    2014-01-01

    We study the achievable rate of a multiple antenna relay-assisted cognitive radio system where a secondary user (SU) aims to communicate instantaneously with the primary user (PU). A special linear precoding scheme is proposed to enable the SU to take advantage of the primary eigenmodes. The used eigenmodes are subject to an interference constraint fixed beforehand by the primary transmitter. Due to the absence of a direct link, both users exploit an amplify-and-forward relay to accomplish their transmissions to a common receiver. After decoding the PU signal, the receiver employs a successive interference cancellation (SIC) to estimate the secondary message. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting interference, peak and relay power constraints. Furthermore, we analyze the SIC detection accuracy on the PU throughput. Numerical results highlight the cognitive rate gain achieved by our proposed scheme without harming the primary rate. In addition, we show that the relay has an important role in increasing or decreasing PU and SU rates especially when varying its power and/or its amplifying gain. © 2014 IFIP.

  8. 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.

  9. Bandwidth and power allocation for two-way relaying in overlay cognitive radio systems

    KAUST Repository

    Alsharoa, Ahmad M.

    2014-12-01

    In this paper, the problem of both bandwidth and power allocation for two-way multiple relay systems in overlay cognitive radio (CR) setup is investigated. In the CR overlay mode, primary users (PUs) cooperate with cognitive users (CUs) for mutual benefits. In our framework, we propose that the CUs are allowed to allocate a part of the PUs spectrum to perform their cognitive transmission. In return, acting as an amplify-and-forward two-way relays, they are used to support PUs to achieve their target data rates over the remaining bandwidth. More specifically, CUs acts as relays for the PUs and gain some spectrum as long as they respect a specific power budget and primary quality-of-service constraints. In this context, we first derive closed-form expressions for optimal transmit power allocated to PUs and CUs in order to maximize the cognitive objective. Then, we employ a strong optimization tool based on particle swarm optimization algorithm to find the optimal relay amplification gains and optimal cognitive released bandwidths as well. Our numerical results illustrate the performance of our proposed algorithm for different utility metrics and analyze the impact of some system parameters on the achieved performance.

  10. On the throughput of a relay-assisted cognitive radio MIMO channel with space alignment

    KAUST Repository

    Sboui, Lokman

    2014-05-01

    We study the achievable rate of a multiple antenna relay-assisted cognitive radio system where a secondary user (SU) aims to communicate instantaneously with the primary user (PU). A special linear precoding scheme is proposed to enable the SU to take advantage of the primary eigenmodes. The used eigenmodes are subject to an interference constraint fixed beforehand by the primary transmitter. Due to the absence of a direct link, both users exploit an amplify-and-forward relay to accomplish their transmissions to a common receiver. After decoding the PU signal, the receiver employs a successive interference cancellation (SIC) to estimate the secondary message. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting interference, peak and relay power constraints. Furthermore, we analyze the SIC detection accuracy on the PU throughput. Numerical results highlight the cognitive rate gain achieved by our proposed scheme without harming the primary rate. In addition, we show that the relay has an important role in increasing or decreasing PU and SU rates especially when varying its power and/or its amplifying gain. © 2014 IFIP.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. On the Coded Packet Relay Network in the Presence of Neighbors:Benefits of Speaking in a Crowded Room

    OpenAIRE

    Khamfroush, Hana; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Hundebøll, Martin; Fitzek, Frank

    2014-01-01

    This paper studies the problem of optimal use of a relay for reducing the transmission time of data packets from a source to a destination using network coding. More importantly, we address an effect that is typically overlooked in previous studies: the presence of active transmitting nodes in the neighborhood of such devices, which is typical in wireless mesh networks. We show that in systems with a fair medium access control mechanism (MAC), the use of a relay in a crowded medium brings for...

  16. Joint Bandwidth and Power Allocation for MIMO Two-Way Relays-Assisted Overlay Cognitive Radio Systems

    KAUST Repository

    Alsharoa, Ahmad; Ghazzai, Hakim; Yaacoub, Elias; Alouini, Mohamed-Slim; Kamal, Ahmed

    2015-01-01

    This paper studies the achievable cognitive sum rate of an overlay cognitive radio (CR) system assisted with multiple antennas two-way relays in which primary users (PUs) cooperate with cognitive users (CUs) for mutual benefits. In this context, the problem of both bandwidth and power allocation is investigated. We propose that the CUs are allowed to allocate a part of the PUs spectrum to perform their cognitive transmission. In return, acting as amplify-and-forward two-way relays, they are exploited to support PUs to reach their target data rates over the remaining bandwidth. Power expressions for optimal transmit power allocated per PU and CU antenna are derived under primary quality-of-service constraint in addition to bandwidth and power budget constraints. More specifically, CUs act as relays for the PUs transmission and gain some spectrum as long as they respect these constraints. After deriving the optimal transmit powers, we employ a strong optimization tool based on swarm intelligence to optimize the full and complex relay amplification gain matrices in addition to the bandwidths released to primary and cognitive transmission. Furthermore, three different utility functions are considered in our optimization problems depending on the level of fairness among CUs.

  17. Joint Bandwidth and Power Allocation for MIMO Two-Way Relays-Assisted Overlay Cognitive Radio Systems

    KAUST Repository

    Alsharoa, Ahmad

    2015-10-08

    This paper studies the achievable cognitive sum rate of an overlay cognitive radio (CR) system assisted with multiple antennas two-way relays in which primary users (PUs) cooperate with cognitive users (CUs) for mutual benefits. In this context, the problem of both bandwidth and power allocation is investigated. We propose that the CUs are allowed to allocate a part of the PUs spectrum to perform their cognitive transmission. In return, acting as amplify-and-forward two-way relays, they are exploited to support PUs to reach their target data rates over the remaining bandwidth. Power expressions for optimal transmit power allocated per PU and CU antenna are derived under primary quality-of-service constraint in addition to bandwidth and power budget constraints. More specifically, CUs act as relays for the PUs transmission and gain some spectrum as long as they respect these constraints. After deriving the optimal transmit powers, we employ a strong optimization tool based on swarm intelligence to optimize the full and complex relay amplification gain matrices in addition to the bandwidths released to primary and cognitive transmission. Furthermore, three different utility functions are considered in our optimization problems depending on the level of fairness among CUs.

  18. 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.

  19. Resource allocation for two source-destination pairs sharing a single relay with a buffer

    KAUST Repository

    Zafar, Ammar

    2014-05-01

    In this paper, we obtain the optimal resource allocation scheme in order to maximize the achievable rate region in a dual-hop system that consists of two independent source-destination pairs sharing a single half-duplex relay. The relay decodes the received information and possesses buffers to enable storing the information temporarily before forwarding it to the respective destination. We consider both non-orthogonal transmission with successive interference cancellation at the receivers and orthogonal transmission. Also, we consider Gaussian block-fading channels and we assume that the channel state information is known and that no delay constraints are required. We show that, with the aid of buffering at the relay, joint user-and-hop scheduling is optimal and can enhance the achievable rate significantly. This is due to the joint exploitation of multiuser diversity and multihop diversity in the system. We provide closed-form expressions to characterize the average achievable rates in a generic form as functions of the statistical model of the channels. Furthermore, we consider sub-optimal schemes that exploit the diversity in the system partially and we provide numerical results to compare the different schemes and demonstrate the gains of the optimal one. © 2014 IEEE.

  20. 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

  1. 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

  2. Rate Maximization in MIMO Decode-and-Forward Communications With an EH Relay and Possibly Imperfect CSI

    KAUST Repository

    Benkhelifa, Fatma

    2016-08-29

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) in a multiple-input multiple-output (MIMO) decode-and-forward (DF) relay system where the relay is an energy harvesting (EH) multi-antenna node equipped with an EH receiver and an information decoding (ID) receiver. The relay harvests the energy from the radio frequency (RF) signals sent by the source and uses it to forward the signals to the destination. The main objective in this paper is to maximize the achievable transmission rate of the overall link by optimizing the source/relay precoders. First, we study an upper bound on the maximum achievable rate where we assume that the EH and ID receivers operate simultaneously and have access to the whole power of the received signals. Afterwards, we study two practical schemes, which are the power splitting (PS) and time switching (TS) schemes, where the ID and EH receivers have partial access to the power or duration of the received signals. For each scheme, we have studied the complexity and the performance comparison. In addition, we considered the case of the imperfect channel estimation error and we have observed its impact on the achievable end-to-end rate and the harvested energy at the relay. © 1972-2012 IEEE.

  3. Protocol Design and Performance Analysis of Multiuser Mixed RF and Hybrid FSO/RF Relaying With Buffers

    KAUST Repository

    Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim

    2018-01-01

    In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay's buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.

  4. Enhancing Physical Layer Security of Multiuser SIMO Mixed RF/FSO Relay Networks with Multi-Eavesdroppers

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2017-02-09

    In this paper, we investigate the secrecy performance of multiuser (MU) single-input multiple-output (SIMO) mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling and multiple eavesdropping attacks. The considered system includes multiple users, one amplify-and-froward (AF) relay, one destination and multiple eavesdroppers. The users are connected with a multi-antenna relay through RF links and the relay is connected with the destination through an FSO link. Maximal ratio combining (MRC) scheme is used at the relay node to combine the received signals at its different antennas. The RF/FSO channels are assumed to follow Nakagami-m/Gamma-Gamma fading models with considering the effect of pointing errors. In particular, we derive closed- form expressions for the exact and asymptotic outage probabilities. The asymptotic outage results are then used to obtain the optimal RF transmission power based on the dominant link between the RF and FSO links. Then, the considered system secrecy performance is investigated in the presence of multi- eavesdroppers where exact closed-form expression for the intercept probability is derived. Finally, a cooperative jamming model is proposed along with power allocation to enhance the system secrecy performance. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

  5. 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.

  6. 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.

  7. 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.

  8. Energy-efficient two-hop LTE resource allocation in high speed trains with moving relays

    KAUST Repository

    Alsharoa, Ahmad M.

    2014-05-01

    High-speed railway system equipped with moving relay stations placed on the middle of the ceiling of each train wagon is investigated. The users inside the train are served in two hops via the 3GPP Long Term Evolution (LTE) technology. The objective of this work is to maximize the number of served users by respecting a specific quality-of-service constraint while minimizing the total power consumption of the eNodeB and the moving relays. We propose an efficient algorithm based on the Hungarian method to find the optimal resource allocation over the LTE resource blocks in order to serve the maximum number of users with the minimum power consumption. Moreover, we derive a closed-form expression for the power allocation problem. Our simulation results illustrate the performance of the proposed scheme and compare it with various previously developed algorithms as well as with the direct transmission scenario. © 2014 IFIP.

  9. Interference Neutralization vs Clean Relaying in Cognitive Radio Networks with Secrecy

    Directory of Open Access Journals (Sweden)

    Pin-Hsun Lin

    2015-08-01

    Full Text Available In this paper we study cognitive radio networks with secrecy constraints on the primary transmission. In particular we consider several transmission schemes for the secondary transmitter, namely interference neutralization (IN and cooperative jamming with and without clean relaying (CR. We derive and analyze the achievable secondary rate performance of the schemes. Furthermore we thoroughly investigate the advantages and shortcomings of these schemes through numerical simulations in a geometric model where we highlight the impact of the users’ locations and show the important difference in all schemes depending on the topology. Our results show that the secondary transmitter can successfully adapt its transmission scheme (and parameters, i.e., either IN or CR, depending on its location to maximize its rate while insuring perfect secrecy of the primary transmission.

  10. 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....

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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...

  5. 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,...

  6. Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

    KAUST Repository

    Chaaban, Anas; Sezgin, Aydin

    2015-01-01

    The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

  7. Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

    KAUST Repository

    Chaaban, Anas

    2015-10-27

    The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

  8. 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.

  9. 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.

  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. 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.

  12. 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 ...

  13. 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...

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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,…

  20. 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....

  1. 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.

  2. 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 ...

  3. 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 ...

  4. 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

  5. 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

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

    Directory of Open Access Journals (Sweden)

    Subhrakanti Dey

    2007-08-01

    Full Text Available 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 power, rate, and transmission time allocation at the wireless links. We further consider an optimal power allocation problem for multiple transmitting sources in the same framework. Performances of the resource allocation algorithms including the effect of buffer load control are illustrated via extensive simulation studies.

  7. 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.

  8. 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....

  9. 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

  10. 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.

  11. Towards Efficient Wireless Body Area Network Using Two-Way Relay Cooperation

    Directory of Open Access Journals (Sweden)

    Maham Waheed

    2018-02-01

    Full Text Available The fabrication of lightweight, ultra-thin, low power and intelligent body-borne sensors leads to novel advances in wireless body area networks (WBANs. Depending on the placement of the nodes, it is characterized as in/on body WBAN; thus, the channel is largely affected by body posture, clothing, muscle movement, body temperature and climatic conditions. The energy resources are limited and it is not feasible to replace the sensor’s battery frequently. In order to keep the sensor in working condition, the channel resources should be reserved. The lifetime of the sensor is very crucial and it highly depends on transmission among sensor nodes and energy consumption. The reliability and energy efficiency in WBAN applications play a vital role. In this paper, the analytical expressions for energy efficiency (EE and packet error rate (PER are formulated for two-way relay cooperative communication. The results depict better reliability and efficiency compared to direct and one-way relay communication. The effective performance range of direct vs. cooperative communication is separated by a threshold distance. Based on EE calculations, an optimal packet size is observed that provides maximum efficiency over a certain link length. A smart and energy efficient system is articulated that utilizes all three communication modes, namely direct, one-way relay and two-way relay, as the direct link performs better for a certain range, but the cooperative communication gives better results for increased distance in terms of EE. The efficacy of the proposed hybrid scheme is also demonstrated over a practical quasi-static channel. Furthermore, link length extension and diversity is achieved by joint network-channel (JNC coding the cooperative link.

  12. Towards Efficient Wireless Body Area Network Using Two-Way Relay Cooperation.

    Science.gov (United States)

    Waheed, Maham; Ahmad, Rizwan; Ahmed, Waqas; Drieberg, Micheal; Alam, Muhammad Mahtab

    2018-02-13

    The fabrication of lightweight, ultra-thin, low power and intelligent body-borne sensors leads to novel advances in wireless body area networks (WBANs). Depending on the placement of the nodes, it is characterized as in/on body WBAN; thus, the channel is largely affected by body posture, clothing, muscle movement, body temperature and climatic conditions. The energy resources are limited and it is not feasible to replace the sensor's battery frequently. In order to keep the sensor in working condition, the channel resources should be reserved. The lifetime of the sensor is very crucial and it highly depends on transmission among sensor nodes and energy consumption. The reliability and energy efficiency in WBAN applications play a vital role. In this paper, the analytical expressions for energy efficiency (EE) and packet error rate (PER) are formulated for two-way relay cooperative communication. The results depict better reliability and efficiency compared to direct and one-way relay communication. The effective performance range of direct vs. cooperative communication is separated by a threshold distance. Based on EE calculations, an optimal packet size is observed that provides maximum efficiency over a certain link length. A smart and energy efficient system is articulated that utilizes all three communication modes, namely direct, one-way relay and two-way relay, as the direct link performs better for a certain range, but the cooperative communication gives better results for increased distance in terms of EE. The efficacy of the proposed hybrid scheme is also demonstrated over a practical quasi-static channel. Furthermore, link length extension and diversity is achieved by joint network-channel (JNC) coding the cooperative link.

  13. Channel Estimation and Optimal Training Design for Correlated MIMO Two-Way Relay Systems in Colored Environment

    OpenAIRE

    Wang, Rui; Tao, Meixia; Mehrpouyan, Hani; Hua, Yingbo

    2014-01-01

    In this paper, while considering the impact of antenna correlation and the interference from neighboring users, we analyze channel estimation and training sequence design for multi-input multi-output (MIMO) two-way relay (TWR) systems. To this end, we propose to decompose the bidirectional transmission links into two phases, i.e., the multiple access (MAC) phase and the broadcasting (BC) phase. By considering the Kronecker-structured channel model, we derive the optimal linear minimum mean-sq...

  14. 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.

  15. 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 ...

  16. Adaptive settings of distance relay for MOV-protected series compensated line with distributed capacitance considering wind power

    Science.gov (United States)

    Sivov, Oleg Viktorovich

    Series compensated lines are protected from overvoltage by metal-oxide-varistors (MOVs) connected in parallel with the capacitor bank. The nonlinear characteristics of MOV devices add complexity to fault analysis and distance protection operation. During faults, the impedance of the line is modified by an equivalent impedance of the parallel MOV/capacitor circuit, which affects the distance protection. The intermittent wind generation introduces additional complexity to the system performance and distance protection. Wind variation affects the fault current level and equivalent MOV/capacitor impedance during a fault, and hence the distance relay operation. This thesis studies the impact of the intermittent wind power generation on the operation of MOV during faults. For the purpose of simulation, an equivalent wind farm model is proposed to generate a wind generation profile using wind farm generation from California independent system operator (ISO) as a guide for wind power variation to perform the study. The IEEE 12-bus test system is modified to include MOV-protected series capacitor and the equivalent wind farm model. The modified test system is simulated in the MATLAB/Simulink environment. The study has been achieved considering three phase and single line to ground (SLG) faults on the series compensated line to show the effect of wind variation on the MOV operation. This thesis proposes an adaptive setting method for the mho relay distance protection of series compensated line considering effects of wind power variation and MOV operation. The distributed parameters of a transmission line are taken into account to avoid overreaching and underreaching of distance relays. The study shows that variable wind power affects system power flow and fault current in the compensated line during a fault which affects the operation of MOVs for different fault conditions. The equivalent per-phase impedance of the MOV/capacitor circuit has an effect on the system operation

  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. 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.

  20. 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.

  1. Secrecy in Wireless Information and Power Transfer for One-Way and Two-Way Untrusted Relaying with Friendly Jamming

    Directory of Open Access Journals (Sweden)

    Lin Xiao

    2017-01-01

    Full Text Available An untrusted relay system combined with a simultaneous wireless information and power transfer (SWIPT scheme is considered in one-way and two-way relaying transmission strategies. In the system, two source nodes can only communicate with each other via an untrusted energy harvesting relay node, which sends the message by using its harvested energy from the source nodes. Specifically, we classify the intermediate relay as an eavesdropper into two modes: active eavesdropper and nonactive eavesdropper, depending on whether it has sufficient energy of its own to transmit the message or not. Under a simplified three-node fading wiretap channel setup, the transmit power allocation and power splitting ratio are jointly optimized to minimize the outage probability in the delay-sensitive case and to maximize the average rate in the delay-insensitive case, subject to the average and peak total power constraints. Applying the dual-decomposition method, the optimization problem can be efficiently solved in the delay-sensitive scenario. Moreover, an iterative algorithm is proposed to derive the solution to maximize the average rate in the delay-insensitive scenario. Numerical results demonstrate the performance of system outage probability in the two modes versus different rates and how efficiently the secrecy rate is improved compared with traditional schemes.

  2. Joint terminals and relay optimization for two-way power line information exchange systems with QoS constraints

    Science.gov (United States)

    Wu, Xiaolin; Rong, Yue

    2015-12-01

    The quality-of-service (QoS) criteria (measured in terms of the minimum capacity requirement in this paper) are very important to practical indoor power line communication (PLC) applications as they greatly affect the user experience. With a two-way multicarrier relay configuration, in this paper we investigate the joint terminals and relay power optimization for the indoor broadband PLC environment, where the relay node works in the amplify-and-forward (AF) mode. As the QoS-constrained power allocation problem is highly non-convex, the globally optimal solution is computationally intractable to obtain. To overcome this challenge, we propose an alternating optimization (AO) method to decompose this problem into three convex/quasi-convex sub-problems. Simulation results demonstrate the fast convergence of the proposed algorithm under practical PLC channel conditions. Compared with the conventional bidirectional direct transmission (BDT) system, the relay-assisted two-way information exchange (R2WX) scheme can meet the same QoS requirement with less total power consumption.

  3. Performance Analysis of a Two-Hop MIMO Mobile-to-Mobile via Stratospheric-Relay Link Employing Hierarchical Modulation

    Directory of Open Access Journals (Sweden)

    Nikolaos Nomikos

    2013-01-01

    Full Text Available Next generation wireless communication networks intend to take advantage of the integration of terrestrial and aerospace infrastructures. Besides, multiple-input multiple-output (MIMO architecture is the key technology, which has brought the wireless gigabit vision closer to reality. In this direction, high-altitude platforms (HAPs could act as relay stations in the stratosphere transferring information from an uplink to a downlink MIMO channel. This paper investigates the performance of a novel transmission scheme for the delivery of mobile-to-mobile (M-to-M services via a stratospheric relay. It is assumed that the source, relay, and destination nodes are equipped with multiple antennas and that amplify-and-forward (AF relaying is adopted. The performance is analyzed through rigorous simulations in terms of the bit-error rate (BER by using a recently proposed 3D geometry-based reference model in spatially correlated flat-fading MIMO channels, employing a hierarchical broadcast technique and minimum mean square error (MMSE receivers.

  4. Transmit Power Minimization and Base Station Planning for High-Speed Trains with Multiple Moving Relays in OFDMA Systems

    KAUST Repository

    Ghazzai, Hakim

    2016-03-15

    High-speed railway system equipped with moving relay stations placed on the middle of the ceiling of each train wagon is investigated. The users inside the train are served in two hops via the orthogonal frequency-division multiple access (OFDMA) technology. In this work, we first focus on minimizing the total downlink power consumption of the base station (BS) and the moving relays while respecting specific quality of service (QoS) constraints. We first derive the optimal resource allocation solution in terms of OFDMA subcarriers and power allocation using the dual decomposition method. Then, we propose an efficient algorithm based on the Hungarian method in order to find a suboptimal but low complexity solution. Moreover, we propose an OFDMA planning solution for high-speed train by finding the maximal inter-BS distance given the required user data rates in order to perform seamless handover. Our simulation results illustrate the performance of the proposed resource allocation schemes in the case of the 3GPP Long Term Evolution-Advanced (LTE-A) and compare them with previously developed algorithms as well as with the direct transmission scenario. Our results also highlight the significant planning gain obtained thanks to the use of multiple relays instead of the conventional single relay scenario.

  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. 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....

  9. On the performance of mixed RF/FSO variable gain dual-hop transmission systems with pointing errors

    KAUST Repository

    Ansari, Imran Shafique; Yilmaz, Ferkan; Alouini, Mohamed-Slim

    2013-01-01

    In this work, the performance analysis of a dualhop relay transmission system composed of asymmetric radiofrequency (RF) and unified free-space optical (FSO) links subject to pointing errors is presented. These unified FSO links account for both

  10. Analysis of overload conditions in distance relay under severe system contingencies

    Energy Technology Data Exchange (ETDEWEB)

    Halim Abu Bakar, Ab. [Department of Electrical Engineering, Universiti Malaya (Malaysia); Yatim, Fazilah Mat; Othman, Mohd Ridzal [Transmission Division, Tenaga Nasional Berhad (Malaysia); Yusof, Sallehuddin [Advanced Powor Solutions (Malaysia)

    2010-06-15

    Distance relay protection is widely used worldwide for protection scheme on high voltage transmission lines. This protection tends to be prone to load encroachment condition causing possible undesired tripping condition. Investigations of two system disturbances that occurred in TNB's (Tenaga Nasional Berhad) Grid in the year 2003 and 2005 have clearly revealed the occurrence of load encroachment condition following line overloads after large number of line tripping. Examination of the impedance locus trajectory during the overload events have enabled a distinction be made between power swing and load encroachment phenomena. This paper presents the analysis and findings of the investigation of the load encroachment phenomena of the two events, including other related transmission line contingencies. (author)

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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....

  1. 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)

  2. 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.

  3. 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.

  4. 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

  5. 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)

  6. Security-Reliability Analysis of Noma-Based Multi-Hop Relay Networks in Presence of an Active Eavesdropper with Imperfect Eavesdropping CSI

    Directory of Open Access Journals (Sweden)

    Tran Tin Phu

    2017-01-01

    Full Text Available In this paper, we evaluate system performances of a multi-hop relay protocol with presence of an active eavesdropper. In the proposed protocol, a source attempts to transmit its data to a destination with assistance of multiple intermediate relays. From the eavesdropping Channel State Information (CSI estimated, the source and relays adjust their transmit power so that the eavesdropper cannot overhear the transmitted data. Moreover, to enhance throughput for the proposed system, Non-Orthogonal Multiple Access (NOMA technique with a simple power allocation is also proposed. We derive exact closed-form expressions of the Outage Probability (OP and throughput for the data transmission over Rayleigh fading channel. In addition, when the CSI estimation is imperfect, Intercept Probability (IP at the eavesdropper is derived. Finally, Monte Carlo simulations are presented to verify the theoretical derivations.

  7. Modeling and Simulation of a Novel Relay Node Based Secure Routing Protocol Using Multiple Mobile Sink for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Madhumathy Perumal

    2015-01-01

    Full Text Available Data gathering and optimal path selection for wireless sensor networks (WSN using existing protocols result in collision. Increase in collision further increases the possibility of packet drop. Thus there is a necessity to eliminate collision during data aggregation. Increasing the efficiency is the need of the hour with maximum security. This paper is an effort to come up with a reliable and energy efficient WSN routing and secure protocol with minimum delay. This technique is named as relay node based secure routing protocol for multiple mobile sink (RSRPMS. This protocol finds the rendezvous point for optimal transmission of data using a “splitting tree” technique in tree-shaped network topology and then to determine all the subsequent positions of a sink the “Biased Random Walk” model is used. In case of an event, the sink gathers the data from all sources, when they are in the sensing range of rendezvous point. Otherwise relay node is selected from its neighbor to transfer packets from rendezvous point to sink. A symmetric key cryptography is used for secure transmission. The proposed relay node based secure routing protocol for multiple mobile sink (RSRPMS is experimented and simulation results are compared with Intelligent Agent-Based Routing (IAR protocol to prove that there is increase in the network lifetime compared with other routing protocols.

  8. 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 ...

  9. 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...

  10. Burst Transmission and Frame Aggregation for VANET Communications

    Directory of Open Access Journals (Sweden)

    Wei Kuang Lai

    2017-09-01

    Full Text Available In vehicular ad hoc networks (VANETs, due to highly mobile and frequently changing topology, available resources and transmission opportunities are restricted. To address this, we propose a burst transmission and frame aggregation (FAB scheme to enhance transmission opportunity (TXOP efficiency of IEEE 802.11p. Aggregation and TXOP techniques are useful for improving transmission performance. FAB aggregates frames in the relay node and utilizes the TXOP to transmit these frames to the next hop with a burst transmission. Simulation results show that the proposed FAB scheme can significantly improve the performance of inter-vehicle communications.

  11. 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.

  12. 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.

  13. 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

  14. 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...

  15. Energy-Efficient Power Allocation for Fixed-Gain Amplify-and-Forward Relay Networks with Partial Channel State Information

    KAUST Repository

    Zafar, Ammar

    2012-06-01

    In this report, energy-efficient transmission and power allocation for fixed-gain amplify-and-forward relay networks with partial channel state information (CSI) are studied. In the energy-efficiency problem, the total power consumed is minimized while keeping the signal-to-noise-ratio (SNR) above a certain threshold. In the dual problem of power allocation, the end-to-end SNR is maximized under individual and global power constraints. Closed-form expressions for the optimal source and relay powers and the Lagrangian multiplier are obtained. Numerical results show that the optimal power allocation with partial CSI provides comparable performance as optimal power allocation with full CSI at low SNR.

  16. Energy-Efficient Power Allocation for Fixed-Gain Amplify-and-Forward Relay Networks with Partial Channel State Information

    KAUST Repository

    Zafar, Ammar

    2012-09-16

    In this letter, energy-efficient transmission and power allocation for fixed-gain amplify-and-forward relay networks with partial channel state information (CSI) are studied. In the energy-efficiency problem, the total power consumed is minimized while keeping the signal-to-noise-ratio (SNR) above a certain threshold. In the dual problem of power allocation, the end-to-end SNR is maximized under individual and global power constraints. Closed-form expressions for the optimal source and relay powers and the Lagrangian multiplier are obtained. Numerical results show that the optimal power allocation with partial CSI provides comparable performance as optimal power allocation with full CSI at low SNR. © 2012 IEEE.

  17. Downlink Multihop Transmission Technique for Asymmetric Traffic Accommodation in DS-CDMA/FDD Cellular Communications

    Science.gov (United States)

    Mori, Kazuo; Naito, Katsuhiro; Kobayashi, Hideo

    This paper proposes an asymmetric traffic accommodation scheme using a multihop transmission technique for CDMA/FDD cellular communication systems. The proposed scheme exploits the multihop transmission to downlink packet transmissions, which require the large transmission power at their single-hop transmissions, in order to increase the downlink capacity. In these multihop transmissions, vacant uplink band is used for the transmissions from relay stations to destination mobile stations, and this leads more capacity enhancement in the downlink communications. The relay route selection method and power control method for the multihop transmissions are also investigated in the proposed scheme. The proposed scheme is evaluated by computer simulation and the results show that the proposed scheme can achieve better system performance.

  18. 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.

  19. New development in relay protection for smart grid : new principles of fault distinction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B.; Hao, Z. [Xi' an Jiaotong Univ., Xian (China); Klimek, A. [Powertech Labs Inc., Surrey, BC (Canada); Bo, Z. [Alstom Grid Automation (United Kingdom)

    2010-07-01

    China is planning to integrate a smart grid into a proposed 750/1000 kV transmission network. However, the performance of the protection relay must be assured in order to have this kind of transmitting capacity. There are many protection strategies that address the many demands of a smart grid, including ultra-high-speed transient-based fault discrimination; new co-ordination principles of main and back-up protection to suit the diversification of the power network; optimal co-ordination between relay protection; and autoreclosure to enhance robustness of the power network. There are also new developments in protection early warning and tripping functions in the protection concepts based on wide area information. This paper presented the principles, algorithms and techniques of single-ended, transient-based and ultra-high-speed protection for extra-high voltage (EHV) transmission lines, buses, DC transmission lines and faulted line selection for non-solid earthed networks. Test results have verified that the proposed methods can determine fault characteristics with ultra-high-speed (5 ms), and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid. High speed Digital Signal Processor (DSP) embedded system techniques combined with optical sensors provide the ability to record and compute detailed fault transients. This technology makes it possible to implement protection principles based on transient information. Due to the inconsistent nature of the wave impedance for various power apparatuses and the reflection and refraction characteristics of their interconnection points, the fault transients contain abundant information about the fault location and type. It is possible to construct ultra high speed and more sensitive AC, DC and busbar main protection through the correct analysis of such information. 23 refs., 6 figs.

  20. 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.

  1. 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.

  2. 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.

  3. Enhanced primary and secondary performance through cognitive relaying and leveraging primary feedback

    KAUST Repository

    Hamza, Doha R.; Aï ssa, Sonia

    2014-01-01

    We consider a spectrum-sharing system, where the primary terminal operates in a time-slotted fashion and is active only when it has a packet to send. The secondary terminal uses spectrum sensing results and the primary automatic repeat request (ARQ) feedback to access the channel probabilistically. To enhance the primary's system performance, the secondary user (SU) acts as a relay for the primary user (PU) in the event of transmission failure on the direct link of the latter. Closed-form expressions for the primary and secondary throughputs are obtained for the described scheme. The optimal medium access probabilities are then obtained by maximizing the secondary throughput subject to constraints that guarantee the stability of the considered queues, a minimum primary throughput, and a maximum primary queueing delay. The results clearly indicate the benefits of cognitive relaying in enhancing the throughput performance for both the PU and SU. Furthermore, by guaranteeing minimum rate and maximum delay requirements, our scheme is shown to provide a definitive notion of protection for the licensed users of the network. © 2013 IEEE.

  4. Enhanced primary and secondary performance through cognitive relaying and leveraging primary feedback

    KAUST Repository

    Hamza, Doha R.

    2014-06-01

    We consider a spectrum-sharing system, where the primary terminal operates in a time-slotted fashion and is active only when it has a packet to send. The secondary terminal uses spectrum sensing results and the primary automatic repeat request (ARQ) feedback to access the channel probabilistically. To enhance the primary\\'s system performance, the secondary user (SU) acts as a relay for the primary user (PU) in the event of transmission failure on the direct link of the latter. Closed-form expressions for the primary and secondary throughputs are obtained for the described scheme. The optimal medium access probabilities are then obtained by maximizing the secondary throughput subject to constraints that guarantee the stability of the considered queues, a minimum primary throughput, and a maximum primary queueing delay. The results clearly indicate the benefits of cognitive relaying in enhancing the throughput performance for both the PU and SU. Furthermore, by guaranteeing minimum rate and maximum delay requirements, our scheme is shown to provide a definitive notion of protection for the licensed users of the network. © 2013 IEEE.

  5. Throughput Analysis on 3-Dimensional Underwater Acoustic Network with One-Hop Mobile Relay

    Science.gov (United States)

    Zhong, Xuefeng; Fan, Jiasheng; Guan, Quansheng; Ji, Fei; Yu, Hua

    2018-01-01

    Underwater acoustic communication network (UACN) has been considered as an essential infrastructure for ocean exploitation. Performance analysis of UACN is important in underwater acoustic network deployment and management. In this paper, we analyze the network throughput of three-dimensional randomly deployed transmitter–receiver pairs. Due to the long delay of acoustic channels, complicated networking protocols with heavy signaling overhead may not be appropriate. In this paper, we consider only one-hop or two-hop transmission, to save the signaling cost. That is, we assume the transmitter sends the data packet to the receiver by one-hop direct transmission, or by two-hop transmission via mobile relays. We derive the closed-form formulation of packet delivery rate with respect to the transmission delay and the number of transmitter–receiver pairs. The correctness of the derivation results are verified by computer simulations. Our analysis indicates how to obtain a precise tradeoff between the delay constraint and the network capacity. PMID:29337911

  6. Throughput Analysis on 3-Dimensional Underwater Acoustic Network with One-Hop Mobile Relay.

    Science.gov (United States)

    Zhong, Xuefeng; Chen, Fangjiong; Fan, Jiasheng; Guan, Quansheng; Ji, Fei; Yu, Hua

    2018-01-16

    Underwater acoustic communication network (UACN) has been considered as an essential infrastructure for ocean exploitation. Performance analysis of UACN is important in underwater acoustic network deployment and management. In this paper, we analyze the network throughput of three-dimensional randomly deployed transmitter-receiver pairs. Due to the long delay of acoustic channels, complicated networking protocols with heavy signaling overhead may not be appropriate. In this paper, we consider only one-hop or two-hop transmission, to save the signaling cost. That is, we assume the transmitter sends the data packet to the receiver by one-hop direct transmission, or by two-hop transmission via mobile relays. We derive the closed-form formulation of packet delivery rate with respect to the transmission delay and the number of transmitter-receiver pairs. The correctness of the derivation results are verified by computer simulations. Our analysis indicates how to obtain a precise tradeoff between the delay constraint and the network capacity.

  7. Harmonics in transmission power systems

    DEFF Research Database (Denmark)

    Wiechowski, Wojciech Tomasz

    . The comparison shows that results obtained used both types of the cores are the same, so it is concluded that both cores can be used for harmonic measurements. Low-inductance resistors are introduced in the secondary circuits, in series with the metering and protective relaying. On those resistors, the harmonic......Some time ago, Energinet.dk, the Transmission System Operator of the 150 kV and 400 kV transmission network in Denmark, had experienced operational malfunctions of some of the measuring and protection equipment. Also an overloading of a harmonic filter has been reported, and therefore, a need...... end only so the ground is not used as a return path. A way to reduce the capacitive coupling is to provide shielding. Harmonic currents are measured using the conventional inductive voltage transformers. Both protective and metering cores were compared if they could be used for harmonic measurements...

  8. 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.

  9. 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.

  10. 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.

  11. Bilayer Protograph Codes for Half-Duplex Relay Channels

    Science.gov (United States)

    Divsalar, Dariush; VanNguyen, Thuy; Nosratinia, Aria

    2013-01-01

    Direct to Earth return links are limited by the size and power of lander devices. A standard alternative is provided by a two-hops return link: a proximity link (from lander to orbiter relay) and a deep-space link (from orbiter relay to Earth). Although direct to Earth return links are limited by the size and power of lander devices, using an additional link and a proposed coding for relay channels, one can obtain a more reliable signal. Although significant progress has been made in the relay coding problem, existing codes must be painstakingly optimized to match to a single set of channel conditions, many of them do not offer easy encoding, and most of them do not have structured design. A high-performing LDPC (low-density parity-check) code for the relay channel addresses simultaneously two important issues: a code structure that allows low encoding complexity, and a flexible rate-compatible code that allows matching to various channel conditions. Most of the previous high-performance LDPC codes for the relay channel are tightly optimized for a given channel quality, and are not easily adapted without extensive re-optimization for various channel conditions. This code for the relay channel combines structured design and easy encoding with rate compatibility to allow adaptation to the three links involved in the relay channel, and furthermore offers very good performance. The proposed code is constructed by synthesizing a bilayer structure with a pro to graph. In addition to the contribution to relay encoding, an improved family of protograph codes was produced for the point-to-point AWGN (additive white Gaussian noise) channel whose high-rate members enjoy thresholds that are within 0.07 dB of capacity. These LDPC relay codes address three important issues in an integrative manner: low encoding complexity, modular structure allowing for easy design, and rate compatibility so that the code can be easily matched to a variety of channel conditions without extensive

  12. 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

  13. Energy Efficient Design for Two-Way AF Relay Networks

    Directory of Open Access Journals (Sweden)

    Yong Li

    2014-01-01

    Full Text Available Conventional designs on two-way relay networks mainly focus on the spectral efficiency (SE rather than energy efficiency (EE. In this paper, we consider a system where two source nodes communicate with each other via an amplify-and-forward (AF relay node and study the power allocation schemes to maximize EE while ensuring a certain data rate. We propose an optimal energy-efficient power allocation algorithm based on iterative search technique. In addition, a closed-form suboptimal solution is derived with reduced complexity and negligible performance degradation. Numerical results show that the proposed schemes can achieve considerable EE improvement compared with conventional designs.

  14. Physical Layer Security Enhancement in Multiuser Mixed RF#x002F;FSO Relay Networks under RF Interference

    KAUST Repository

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

    2017-01-01

    In this paper, the impact of radio frequency (RF) co-channel interference (CCI) on the performance of multiuser (MU) mixed RF#x002F;free space optical (FSO) relay network with opportunistic user scheduling is studied. In the considered system, a user is opportunistically selected to communicate with a single destination through an amplify-and- forward (AF) relay in the presence of a single passive eavesdropper. The RF#x002F;FSO channel models are assumed to follow Rayleigh#x002F;Gamma-Gamma fading models, respectively with pointing errors and identical RF CCI signals. Exact closed-form expression for the system outage probability is derived. Then, an asymptotic expression for the outage probability is obtained at the high signal- to-interference-plus-noise ratio (SINR) regime. The asymptotic results are used to formulate a power allocation problem to obtain optimal RF transmission power. Then, the secrecy performance is studied in the presence of CCI at both the authorized relay and eavesdropper by obtaining exact and asymptotic closed-form expressions for the intercept probability. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the work.

  15. Physical Layer Security Enhancement in Multiuser Mixed RF#x002F;FSO Relay Networks under RF Interference

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2017-05-12

    In this paper, the impact of radio frequency (RF) co-channel interference (CCI) on the performance of multiuser (MU) mixed RF#x002F;free space optical (FSO) relay network with opportunistic user scheduling is studied. In the considered system, a user is opportunistically selected to communicate with a single destination through an amplify-and- forward (AF) relay in the presence of a single passive eavesdropper. The RF#x002F;FSO channel models are assumed to follow Rayleigh#x002F;Gamma-Gamma fading models, respectively with pointing errors and identical RF CCI signals. Exact closed-form expression for the system outage probability is derived. Then, an asymptotic expression for the outage probability is obtained at the high signal- to-interference-plus-noise ratio (SINR) regime. The asymptotic results are used to formulate a power allocation problem to obtain optimal RF transmission power. Then, the secrecy performance is studied in the presence of CCI at both the authorized relay and eavesdropper by obtaining exact and asymptotic closed-form expressions for the intercept probability. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the work.

  16. Adaptive Subframe Partitioning and Efficient Packet Scheduling in OFDMA Cellular System with Fixed Decode-and-Forward Relays

    Science.gov (United States)

    Wang, Liping; Ji, Yusheng; Liu, Fuqiang

    The integration of multihop relays with orthogonal frequency-division multiple access (OFDMA) cellular infrastructures can meet the growing demands for better coverage and higher throughput. Resource allocation in the OFDMA two-hop relay system is more complex than that in the conventional single-hop OFDMA system. With time division between transmissions from the base station (BS) and those from relay stations (RSs), fixed partitioning of the BS subframe and RS subframes can not adapt to various traffic demands. Moreover, single-hop scheduling algorithms can not be used directly in the two-hop system. Therefore, we propose a semi-distributed algorithm called ASP to adjust the length of every subframe adaptively, and suggest two ways to extend single-hop scheduling algorithms into multihop scenarios: link-based and end-to-end approaches. Simulation results indicate that the ASP algorithm increases system utilization and fairness. The max carrier-to-interference ratio (Max C/I) and proportional fairness (PF) scheduling algorithms extended using the end-to-end approach obtain higher throughput than those using the link-based approach, but at the expense of more overhead for information exchange between the BS and RSs. The resource allocation scheme using ASP and end-to-end PF scheduling achieves a tradeoff between system throughput maximization and fairness.

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

    KAUST Repository

    Benjillali, Mustapha; Szczecinski, Leszek

    2010-01-01

    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

  18. Relay Placement for FSO Multihop DF Systems With Link Obstacles and Infeasible Regions

    KAUST Repository

    Zhu, Bingcheng; Cheng, Julian; Alouini, Mohamed-Slim; Wu, Lenan

    2015-01-01

    Optimal relay placement is studied for free-space optical multihop communication with link obstacles and infeasible regions. An optimal relay placement scheme is proposed to achieve the lowest outage probability, enable the links to bypass obstacles

  19. Experimental study on the EMP failure mode of DC solid state relay

    International Nuclear Information System (INIS)

    Sun Beiyun; Chen Xiangyue; Zhai Aibin; Mao Congguang

    2009-01-01

    DC solid state relay is a new type switch device without touch point, and is extensive used by aviation and spaceflight technique. In this paper, the EMP failure modes of solid state relays were obtained by current injection method. (authors)

  20. Physical-Layer Security of a Buffer-Aided Full-Duplex Relaying System

    KAUST Repository

    El Shafie, Ahmed

    2016-07-07

    This letter proposes a novel hybrid half-/full-duplex relaying scheme to enhance the relay channel security. A source node (Alice) communicates with her destination node (Bob) in the presence of a buffer-aided full-duplex relay node (Rooney) and a potential eavesdropper (Eve). Rooney adopts two different relaying, namely randomize-and-forward and decode-andforward relaying strategies, to improve the security of the legitimate system. In the first relaying strategy, Rooney uses a codebook different from that used at Alice. In the second relaying strategy, Rooney and Alice use the same codebooks. In addition, Rooney switches between half-duplex and full-duplex modes to further enhance the security of the legitimate system. The numerical results demonstrate that our proposed scheme achieves a significant average secrecy end-to-end throughput improvement relative to the conventional bufferless full-duplex relaying scheme.