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Sample records for half-duplex out-of-band relay

  1. 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.

  2. 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.

  3. Bilayer Protograph Codes for Half-Duplex Relay Channels

    Science.gov (United States)

    Divsalar, Dariush; VanNguyen, Thuy; Nosratinia, Aria

    2013-01-01

    re-optimization. The main problem of half-duplex relay coding can be reduced to the simultaneous design of two codes at two rates and two SNRs (signal-to-noise ratios), such that one is a subset of the other. This problem can be addressed by forceful optimization, but a clever method of addressing this problem is via the bilayer lengthened (BL) LDPC structure. This method uses a bilayer Tanner graph to make the two codes while using a concept of "parity forwarding" with subsequent successive decoding that removes the need to directly address the issue of uneven SNRs among the symbols of a given codeword. This method is attractive in that it addresses some of the main issues in the design of relay codes, but it does not by itself give rise to highly structured codes with simple encoding, nor does it give rate-compatible codes. The main contribution of this work is to construct a class of codes that simultaneously possess a bilayer parity- forwarding mechanism, while also benefiting from the properties of protograph codes having an easy encoding, a modular design, and being a rate-compatible code.

  4. On the Diversity-Multiplexing Tradeoff of the Half-Duplex DDF MIMO Relay Protocol

    Science.gov (United States)

    Yoon, Eunchul; Kim, Sun-Yong; Choi, Suhan

    The analytical derivation of the diversity-multiplexing tradeoff (DMT) for a half-duplex dynamic decode and forward (DDF) MIMO relay protocol has been regarded as an open problem. Recently, however, a minimization problem setting has been found, the solution of which corresponds to the DMT function for a half-duplex DDF MIMO relay protocol. In this paper, the DMT functions for three special half-duplex DDF MIMO relay protocols using two antennas at two of three nodes, source, relay, and destination nodes, and a single antenna at the other node are derived first. Then, the DMT function for a special half-duplex DDF MIMO relay protocol using two antennas at every node is derived. These DDF MIMO relay protocols are compared with one another and with some NAF MIMO relay protocols by simulation.

  5. Interference alignment for degrees of freedom improvement in 3-relay half-duplex systems

    KAUST Repository

    Park, Seongho

    2011-12-01

    In a half-duplex relaying, the capacity pre-log factor is a major drawback in spectral efficiency. This paper proposes a linear precoding 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 eliminate the inter-relay interference resulted 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. © 2011 IEEE.

  6. The Half-Duplex AWGN Single-Relay Channel: Full Decoding or Partial Decoding?

    CERN Document Server

    Ong, Lawrence; Kellett, Christopher M

    2011-01-01

    This paper compares the partial-decode-forward and the complete-decode-forward coding strategies for the half-duplex Gaussian single-relay channel. We analytically show that partial-decode-forward outperforms the more straightforward complete-decode-forward by at most 12.5%, for any channel parameters. Furthermore, in the following asymptotic cases, complete-decode-forward achieves the same rates as partial-decode-forward does: (i) when the relay is close to the source, (ii) when the relay is close to the destination, and (iii) when the SNR is low. In addition, when the SNR increases, the normalized gap between the rates achievable by the two coding strategies diminishes. Consequently, significant performance improvements are not achieved by optimizing the fraction of data the relay should decode and forward.

  7. The diversity-multiplexing tradeoff of the symmetric MIMO half-duplex relay channel

    CERN Document Server

    Karmakar, Sanjay

    2010-01-01

    The diversity-multiplexing tradeoff (DMT) is obtained for the symmetric MIMO half-duplex (HD) relay channel where the source and the destination have $n$ antennas each and the relay node has $m$ antennas (hereafter, such a channel is referred to as an $(n,m)$-relay channel). The characterization of the DMT requires the joint eigenvalue distribution of three specially correlated central Wishart random matrices, which is derived using a related result in [1], [2]. The explicit characterization of the DMT, besides providing the theoretical benchmark for evaluating performance of practical cooperative protocols on this channel, reveals several interesting facts such as: a) the HD operation of the relay fundamentally limits relay channel performance in the sense that the DMT of the full-duplex (FD) relay channel can be strictly greater than that of the HD relay channel; b) an extra antenna at the relay node on a HD relay channel does not always improve the achievable diversity order, unlike that on an FD relay cha...

  8. Towards Optimal Schemes for the Half-Duplex Two-Way Relay Channel

    CERN Document Server

    Stein, Manuel

    2011-01-01

    A restricted two-way communication problem in a small network is investigated. The network consists of three nodes, all having access to a common channel with half-duplex constraint. Two nodes want to establish a dialog while the third node can assist in the bi-directional transmission process. All nodes have agreed on a transmission protocol a priori and the problem is restricted to the dialog encoders not being allowed to establish a cooperation by the use of previous receive signals. The channel is referred to as the restricted half-duplex two-way relay channel. Here the channel is defined and an outer bound on the achievable rates is derived by the application of the Cut-set Theorem. This shows that the problem consists of six parts. By the use of random codes and suboptimal decoders an inner bound on the achievable rates with decoding at the relay is established. Restricting to this relaying strategy and fixed input distributions makes it possible to determine optimal transmission schemes with respect to...

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

    KAUST Repository

    Rabie, Khaled M.

    2017-08-15

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

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

    KAUST Repository

    Zafar, Ammar

    2013-09-01

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

  11. Reliability Capacity of Half-Duplex Channels with Strict Deadlines

    DEFF Research Database (Denmark)

    Costa, Rui; Roetter, Daniel Enrique Lucani; Vinhoza, Tiago

    2015-01-01

    A fundamental characterization of a half-duplex wireless system with packet losses under traffic with hard deadlines is instrumental to understanding and developing efficient, coding aware policies for real-time applications. We set forth the concept of reliability capacity with a limited number...

  12. 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.

  13. Physical Layer Security Using Two-Path Successive Relaying.

    Science.gov (United States)

    Liau, Qian Yu; Leow, Chee Yen; Ding, Zhiguo

    2016-06-09

    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.

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

    KAUST Repository

    Park, Kihong

    2012-06-01

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

  15. Full Duplex Emulation via Spatial Separation of Half Duplex Nodes in a Planar Cellular Network

    DEFF Research Database (Denmark)

    Thomsen, Henning; Kim, Dong Min; Popovski, Petar

    2016-01-01

    (HD-BSs), which is a scheme termed CoMPflex (CoMP for In-Band Wireless Full Duplex). A FD-BS can be seen as a special case of CoMPflex with separation distance zero. In this paper we study the performance of CoMPflex in a two-dimensional cellular scenario using stochastic geometry and compare......A Full Duplex Base Station (FD-BS) can be used to serve simultaneously two Half-Duplex (HD) Mobile Stations (MSs), one working in the uplink and one in the downlink, respectively. The same functionality can be realized by having two interconnected and spatially separated Half Duplex Base Stations...

  16. 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.

  17. A Half-duplex Synchronous Serial Fieldbus S2CAN with Multi-host Structure

    Directory of Open Access Journals (Sweden)

    Xu-Fei SUN

    2014-10-01

    Full Text Available This paper describes a field bus of which the physical layer using CAN (Controller Area Network transmission line and the data link layer using SPI (Serial Peripheral Interface interface protocol. It uses half-duplex transmission mode, which can be used to build a LAN (Local Area Network control system with multi-host structure. The bus takes advantage of the electrical characteristics of CAN transmission line, inheriting its anti-interference ability and the advantage of long transmission distance. Also, it inherits the merits of SPI bus in fast communication, simple use and low cost. The paper describes the communication protocol and hardware and software implementation of the novel fieldbus and gives the experimental data and test results to verify the feasibility of the novel fieldbus and excellent communication characteristics.

  18. 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.

  19. 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 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...

  20. 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......-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...

  1. Out-of-band effects of satellite ocean color sensors.

    Science.gov (United States)

    Wang, Menghua; Naik, Puneeta; Son, SeungHyun

    2016-03-20

    We analyze the sensor out-of-band (OOB) effects for satellite ocean color sensors of the sea-viewing wild field-of-view sensor (SeaWiFS), the moderate resolution imaging spectroradiometer (MODIS), and the visible infrared imaging radiometer suite (VIIRS) for phytoplankton-dominated open oceans and turbid coastal and inland waters, following the approach of Wang et al. [Appl. Opt.40, 343 (2001)APOPAI0003-693510.1364/AO.40.000343]. The applicability of the open ocean water reflectance model of Morel and Maritorena [J. Geophys. Res.106, 7163 (2001)JGREA20148-022710.1029/2000JC000319] (MM01) for the sensor OOB effects is analyzed for oligotrophic waters in Hawaii. The MM01 model predicted OOB contributions for oligotrophic waters are consistent with the result from in situ measurements. The OOB effects cause an apparent shift in sensor band center wavelengths in radiometric response, which depends on the sensor spectral response function and the target radiance being measured. Effective band center wavelength is introduced and calculated for three satellite sensors and for various water types. Using the effective band center wavelengths, satellite and in situ measured water optical property data can be more meaningfully and accurately compared. It is found that, for oligotrophic waters, the OOB effect is significant for the SeaWiFS 555 nm band (and somewhat 510 nm band), MODIS 412 nm band, and VIIRS 551 nm band. VIIRS and SeaWiFS have similar sensor OOB performance. For coastal and inland waters, however, the OOB effect is generally not significant for all three sensors, even though some small OOB effects do exist. This study highlights the importance of understanding the sensor OOB effect and the necessity of a complete prelaunch sensor characterization on the quality of ocean color products. Furthermore, it shows that hyperspectral in situ optics measurements are preferred for the purpose of accurately validating satellite-measured normalized water

  2. 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

  3. 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.

  4. Digitally Enhanced Software-Defined Radio Receiver Robust to Out-of-Band Interference

    NARCIS (Netherlands)

    Ru, Z.; Moseley, N.A.; Klumperink, Eric A.M.; Nauta, Bram

    2009-01-01

    Abstract—A software-defined radio (SDR) receiver with improved robustness to out-of-band interference (OBI) is presented. Two main challenges are identified for an OBI-robust SDR receiver: out-of-band nonlinearity and harmonic mixing. Voltage gain at RF is avoided, and instead realized at baseband

  5. 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.

  6. Clustering Optimization for Out-of-Band D2D Communications

    Directory of Open Access Journals (Sweden)

    A. Paramonov

    2017-01-01

    Full Text Available Significant increase in multimedia traffic challenges 5G networks in terms of capacity and correspondent QoS parameters. Device-to-device communication paradigm has already become an integral part of 3GPP standards; nevertheless it has not yet been widely deployed due to many different reasons. D2D is expected to leverage implementation of many qualitatively new services and to efficiently accomplish it D2D devices are supposed to form clusters. Due to practical limitations, current D2D implementations are mostly out-of-band and use Wi-Fi Direct. In this paper, we propose a novel model for throughput optimization in out-of-band D2D clusters. We delivered numerical results for different typical cluster member distributions and revealed key functional dependencies. Further, for the first time we compare clustering algorithms for out-of-band D2D and identify effective clustering algorithm that increases network resource utilization rate.

  7. 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.

  8. 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.

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    del Coso Aitor

    2007-01-01

    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 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, . Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  11. 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.

  12. A Software-Defined Radio Receiver Architecture Robust to Out-of-Band Interference

    NARCIS (Netherlands)

    Ru, Z.; Klumperink, Eric A.M.; Wienk, Gerhardus J.M.; Nauta, Bram

    2009-01-01

    In a software-defined radio (SDR) receiver it is desirable to minimize RF band-filtering for flexibility, size and cost reasons, but this leads to increased out-of-band interference (OBI). Besides harmonic and intermodulation distortion (HD/IMD), OBI can also lead to blocking and harmonic mixing. A

  13. 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.

  14. Efficient Relay Selection Scheme for Delay-Limited Non-Orthogonal Hybrid-ARQ Relay Channels

    CERN Document Server

    Maham, Behrouz; Debbah, Merouane

    2012-01-01

    We consider a half-duplex wireless relay network with hybrid-automatic retransmission request (HARQ) and Rayleigh fading channels. In this paper, we analyze the outage probability of the multi-relay delay-limited HARQ system with opportunistic relaying scheme in decode-and-forward mode, in which the \\emph{best} relay is selected to transmit the source's regenerated signal. A simple and distributed relay selection strategy is proposed for multi-relay HARQ channels. Then, we utilize the non-orthogonal cooperative transmission between the source and selected relay for retransmitting of the source data toward the destination if needed, using space-time codes or beamforming techniques. We analyze the performance of the system. We first derive the cumulative density function (CDF) and probability density function (PDF) of the selected relay HARQ channels. Then, the CDF and PDF are used to determine the outage probability in the $l$-th round of HARQ. The outage probability is required to compute the throughput-delay...

  15. 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.

  16. A Circular Polarized Rectenna with Out-of-Band Suppression for Microwave Power Transmission

    Directory of Open Access Journals (Sweden)

    Weijun Hong

    2016-01-01

    Full Text Available A novel circular polarized rectenna with out-of-band suppression is proposed in this paper. The circular polarization is realized by corner perturbation on a rectangular radiation patch and enhanced by a diagonal slim slot etched at the center of the patch. An open stub connecting to the quarter wavelength impedance transformer is used to suppress out-of-band wave through harmonics notching. The results of simulations and experiments agree very well, which show that the rectenna obtained −19 dB return loss at 2.4 GHz and −15.5 dB, −18.1 dB, and −11.4 dB suppression on second, third, and fourth harmonic frequency bands, respectively. The reflection coefficient in overall out-of-band, up to 10 GHz, is limited up to −3 dB. Integrated with a voltage doubling rectification circuit, the proposed rectenna can obtain 75.5% RF-to-DC conversion efficiency.

  17. Study of Gaussian Relay Channels with Correlated Noises

    CERN Document Server

    Zhang, Lili; Goldsmith, Andrea J; Cui, Shuguang

    2010-01-01

    In this paper, we consider full-duplex and half-duplex Gaussian relay channels where the noises at the relay and destination are arbitrarily correlated. We first derive the capacity upper bound and the achievable rates with three existing schemes: Decode-and-Forward (DF), Compress-and-Forward (CF), and Amplify-and-Forward (AF). We present two capacity results under specific noise correlation coefficients, one being achieved by DF and the other being achieved by direct link transmission (or a special case of CF). The channel for the former capacity result is equivalent to the traditional Gaussian degraded relay channel and the latter corresponds to the Gaussian reversely-degraded relay channel. For CF and AF schemes, we show that their achievable rates are strictly decreasing functions over the negative correlation coefficient. Through numerical comparisons under different channel settings, we observe that although DF completely disregards the noise correlation while the other two can potentially exploit such ...

  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. A Software-Defined Radio Receiver in 65nm CMOS Robust to Out-of-Band Interference

    NARCIS (Netherlands)

    Ru, Z.; Klumperink, Eric A.M.; Wienk, Gerhardus J.M.; Nauta, Bram

    2009-01-01

    Abstract — Two techniques are presented in this paper for a software-defined radio (SDR) receiver robust to out-of-band interference. Voltage gain is realized at IF simultaneously with low-pass filtering to mitigate blockers and out-of-band intermodulation distortion. A 2-stage polyphase harmonic

  20. 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.

  1. 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.

  2. Tunable Photonic Radiofrequency Filter with A Record High Out-Of-Band Rejection

    CERN Document Server

    Li, Peixuan; Pan, Wei; Yan, Lianshan; Pan, Shilong

    2016-01-01

    As radiofrequency filtering plays a vital role in electromagnetic devices and systems, recently photonic techniques have been intensively studied to implement radiofrequency filters to harness wide frequency coverage, large instantaneous bandwidth, low frequency-dependent loss, flexible tunability and strong immunity to electromagnetic interference. However, one crucial challenge facing the photonic radiofrequency filter (PRF) is the less impressive out-of-band rejection, normally less than 70 dB (see Table I). Here, to the best of our knowledge, we demonstrate a tunable PRF with a record out-of-band rejection of 80 dB, which is one order of magnitude higher than the maximum value (~70 dB) reported so far, when incorporating highly selective polarization control and large narrow-band amplification enabled by stimulated Brillouin scattering effect. Tunable central frequency ranging from 2.1 to 6.1 GHz is also demonstrated. Moreover, the proposed PRF is an active one capable of providing negligible insertion lo...

  3. Out-of-Band 40 DB Bandwidth of EESS (Active) Spaceborne SARS

    Science.gov (United States)

    Huneycutt, Bryan L.

    2005-01-01

    This document presents a study of out of band (OOB) 40 dB bandwidth requirements of spaceborne SARs in the Earth Exploration-Satellite Service (active) and Space Research Service (active). The purpose of the document is to study the OOB 40 dB bandwidth requirements and compare the 40 dB bandwidth B-40 as measured in simulations with that calculated using the ITU-R Rec SM.1541 equations. The spectra roll-off and resulting OOB 40 dB bandwidth of the linear FM signal is affected by the time-bandwidth product and the rise/fall times. Typical values of these waveform characteristics are given for existing EESS (active) sensors.

  4. Embedded top-coat for reducing the effect out of band radiation in EUV lithography

    Science.gov (United States)

    Du, Ke; Siauw, Meiliana; Valade, David; Jasieniak, Marek; Voelcker, Nico; Trefonas, Peter; Thackeray, Jim; Blakey, Idriss; Whittaker, Andrew

    2017-03-01

    Out of band (OOB) radiation from the EUV source has significant implications for the performance of EUVL photoresists. Here we introduce a surface-active polymer additive, capable of partitioning to the top of the resist film during casting and annealing, to protect the underlying photoresist from OOB radiation. Copolymers were prepared using reversible addition-fragmentation chain transfer (RAFT) polymerization, and rendered surface active by chain extension with a block of fluoro-monomer. Films were prepared from the EUV resist with added surface-active Embedded Barrier Layer (EBL), and characterized using measurements of contact angles and spectroscopic ellipsometry. Finally, the lithographic performance of the resist containing the EBL was evaluated using Electron Beam Lithography exposure

  5. Impact of I/Q imbalance on the performance of two-way CSI-assisted AF relaying

    KAUST Repository

    Qi, Jian

    2013-04-01

    In this paper, we investigate half-duplex two-way dual-hop channel state information (CSI)-assisted amplify-and-forward (AF) relaying in the presence of in-phase and quadrature-phase (I/Q) imbalance. A compensation approach for the I/Q imbalance is proposed, which employs the received signals together with their conjugations to detect the desired signal. We also derive the average symbol error probability of the considered half-duplex two-way dual-hop CSI-assisted AF relaying networks with and without compensation for I/Q imbalance in Rayleigh fading channels. Numerical results are provided and show that the proposed compensation method mitigates the impact of I/Q imbalance to a certain extent. © 2013 IEEE.

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

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-08-01

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

  7. Downlink Error Rates of Half-duplex Users in Full-duplex Networks over a Laplacian Inter-User Interference Limited and EGK fading

    KAUST Repository

    Soury, Hamza

    2017-03-14

    This paper develops a mathematical framework to study downlink error rates and throughput for half-duplex (HD) terminals served by a full-duplex (FD) base station (BS). The developed model is used to motivate long term pairing for users that have non-line of sight (NLOS) interfering link. Consequently, we study the interferer limited problem that appears between NLOS HD users-pair that are scheduled on the same FD channel. The distribution of the interference is first characterized via its distribution function, which is derived in closed form. Then, a comprehensive performance assessment for the proposed pairing scheme is provided by assuming Extended Generalized- $cal{K}$ (EGK) fading for the downlink and studying different modulation schemes. To this end, a unified closed form expression for the average symbol error rate is derived. Furthermore, we show the effective downlink throughput gain harvested by the pairing NLOS users as a function of the average signal-to-interferenceratio when compared to an idealized HD scenario with neither interference nor noise. Finally, we show the minimum required channel gain pairing threshold to harvest downlink throughput via the FD operation when compared to the HD case for each modulation scheme.

  8. Cooperation schemes for rate enhancement in detect-and-forward relay channels

    KAUST Repository

    Benjillali, Mustapha

    2010-05-01

    To improve the spectral efficiency of "Detect-and-Forward" (DetF) half-duplex relaying in fading channels, we propose a cooperation scheme where the relay uses a modulation whose order is higher than the one at the source. In a new common framework, we show that the proposed scheme offers considerable gains - in terms of achievable information rates - compared to the conventional DetF relaying schemes for both orthogonal and non-orthogonal source/relay cooperation. This allows us to propose an adaptive cooperation scheme based on the maximization of the information rate at the destination which needs to observe only the average signal-to-noise ratios of direct and relaying links. ©2010 IEEE.

  9. Two-way CSI-assisted AF relaying with HPA nonlinearity

    KAUST Repository

    Qi, Jian

    2015-09-11

    In this paper, we investigate half-duplex two-way dual-hop channel state information (CSI)-assisted amplify-andforward (AF) relaying in the presence of high-power amplifier (HPA) nonlinearity at relays. The expression for the end-toend signal-to-noise ratio (SNR) is derived as per the modified system model by taking into account the interference caused by relaying scheme and HPA nonlinearity. The system performance of the considered relaying network is evaluated in terms of average symbol error probability (SEP) in Nakagami-m fading channels, by making use of the moment-generating function (MGF) approach. Numerical results are provided and show the effects of several parameters, such as quadrature amplitude modulation (QAM) order, number of relays, HPA parameters, and Nakagami parameter, on performance. © 2015 IEEE.

  10. Ultraviolet out-of-band radiation studies in laser tin plasma sources

    Science.gov (United States)

    Parchamy, Homaira; Szilagyi, John; Masnavi, Majid; Richardson, Martin

    2017-11-01

    Out-of-band long wavelength emission measurements from high power, high-repetition-rate extreme-ultra-violet lithography (EUVL) laser plasma sources are imperative to estimating heat deposition in EUV mirrors, and the impact of short wavelength light transported through the imaging system to the wafer surface. This paper reports a series of experiments conducted to measure the absolute spectral irradiances of laser-plasmas produced from planar tin targets over the wavelength region of 124 to 164 nm by 1.06 μm wavelength, 10 ns full-width-at-half-maximum Gaussian laser pulses. The use of spherical targets is relevant to the EUVL source scenario. Although plasmas produced from planar surfaces evolve differently, there is a close similarity to the evolution of current from 10.6 μm CO2 laser EUVL sources, which use a pre-pulse from a lower energy solid-state laser to melt and reform an initial spherical droplet into a thin planar disc target. The maximum of radiation conversion efficiency in the 124-164 nm wavelength band (1%/2πsr) occurs at the laser intensity of 1010 W cm-2. A developed collisional-radiative model reveals the strong experimental spectra that originate mainly from the 4d105p2-4d105s5p, 4d105p-4d105s resonance lines, and 4d95p-4d95s unresolved transition arrays from Sn III, Sn IV, and Sn V ions, respectively. The calculated conversion efficiencies using a 2D radiation-hydrodynamics model are in agreement with the measurements. The model predicts the out-of-band (100-400 nm) radiation conversion efficiencies generated by both 1.06 and 10.6 μm pulses. The 10.6 μm laser pulse produces a higher conversion efficiency (12%/2πsr) at the lower laser intensity of 109 W cm-2.

  11. Out-of-band emission suppression techniques based on a generalized OFDM framework

    Science.gov (United States)

    You, Zihao; Fang, Juan; Lu, I.-Tai

    2014-12-01

    Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-band emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.

  12. Interleaving Gains for Receive Diversity Schemes of Distributed Turbo Codes in Wireless Half–Duplex Relay Channels

    Directory of Open Access Journals (Sweden)

    Tamer H. M. Soliman

    2015-06-01

    Full Text Available This paper proposes the interleaving gain in two different distributed turbo-coding schemes: Distributed Turbo Codes (DTC and Distributed Multiple Turbo Codes (DMTC for half-duplex relay system as an extension of our previous work on turbo coding interleaver design for direct communication channel. For these schemes with half-duplex constraint, the source node transmits its information with the parity bit sequence(s to both the relay and the destination nodes during the first phase. The relay received the data from the source and process it by using decode and forward protocol. For the second transmission period, the decoded systematic data at relay is interleaved and re-encoded by a Recursive Systematic Convolutional (RSC encoder and forwarded to the destination. At destination node, the signals received from the source and relay are processed by using turbo log-MAP iterative decoding for retrieving the original information bits. We demonstrate via simulations that the interleaving gain has a large effect with DTC scheme when we use only one RSC encoder at both the source and relay with best performance when using Modified Matched S-Random (MMSR interleaver. Furthermore, by designing a Chaotic Pseudo Random Interleaver (CPRI as an outer interleaver at the source node instead of classical interleavers, our scheme can add more secure channel conditions.

  13. 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

  14. 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

  15. A 115dB-DR Audio DAC with –61dBFS out-of-band noise

    NARCIS (Netherlands)

    Westerveld, H.J.; Schinkel, Daniel; van Tuijl, Adrianus Johannes Maria

    2015-01-01

    Out-of-band noise (OBN) is troublesome in analog circuits that process the output of a noise-shaping audio DAC. It causes slewing in amplifiers and aliasing in sampling circuits like ADCs and class-D amplifiers. Nonlinearity in these circuits also causes cross-modulation of the OBN into the audio

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

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-06-01

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

  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......-layer coding scheme is proposed, where physical layer channel coding is utilized within each packet for error-correction and random network coding is applied on top of channel coding for network error-control. There is a natural tradeoff between the physical layer coding rate and the network coding rate given...

  18. Optimal Waveform of the Partial-Respond Signal Based on Minimum Out-of-Band Radiation Criterion

    Directory of Open Access Journals (Sweden)

    Wenjing Shang

    2017-10-01

    Full Text Available This paper presents a novel method designing an optimized waveform with high spectral efficiency based on minimum out-of-band radiation criterion. Introducing the Pan-function model, Fourier series, and constraints, we achieve the numeric solution of the optimized baseband signals. The optimal waveform provides an excellent bandwidth efficiency, and its bit error rate (BER performance is improved using the minimum cross-correlation function. To verify the proposed model, we present a simulation of the signal modulation and demodulation schemes using MATLAB software. The results are consistent with expected results, verifying the correctness of this method.

  19. Simultaneous Out-of-band Interference Rejection and Radiation Enhancement in an Electronic Product via an EBG Structure

    DEFF Research Database (Denmark)

    Ruaro, Andrea; Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2014-01-01

    to achieve simultaneously both the enhancement of the antenna radiation efficiency and the shrinking of its dimensions, while making the device more resilient to out-of-band electromagnetic interference (EMI). The patterning of the ground plane allows, in fact, to effectively suppress higher-order resonances......This work presents an application of a planar electromagnetic band gap (EBG) structure with a perspective product implementation in the back of the mind. The focus is on the integration of such structure under the constraint of space and system coexistence. It is discovered that it is possible...... (alternatively, parallel plate noise) and decrease the radiation efficiency of the structure forbidding higher-order modes to propagate and subsequently be diffracted by the ground plane....

  20. Diversity-Multiplexing Tradeoff in the Multiaccess Relay Channel with Finite Block Length

    CERN Document Server

    Lee, Chung-Pi

    2011-01-01

    The Dynamic Decode-and-Forward (DDF) protocol and the Hybrid DDF and Amplified-and-Forward (HDAF) protocol for the multiple-access relay channel (MARC) with quasi static fading are evaluated using the Zheng-Tse diversity-multiplexing tradeoff (DMT). We assume that there are two users, one half-duplex relay, and a common destination, each equipped with single antenna. For the Rayleigh fading, the DDF protocol is well known and has been analyzed in terms of the DMT with infinite block length. By carefully dealing with properties specific to finite block length, we characterize the finite block length DMT which takes into account the fact that the event of decoding error at the relay causes the degradation in error performance when the block length is finite. Furthermore, we consider the situation where the destination does not have a priori knowledge of the relay decision time at which the relay switches from listening to transmitting. By introducing a decision rejection criterion such that the relay forwards m...

  1. 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.

  2. Joint Subcarrier Pairing and Power Allocation for OFDM Transmission with Decode-and-Forward Relaying

    CERN Document Server

    Hsu, Chih-Ning; Lin, Pin-Hsun

    2010-01-01

    In this paper, a point-to-point Orthogonal Frequency Division Multiplexing (OFDM) system with a decode-and-forward (DF) relay is considered. The transmission consists of two hops. The source transmits in the first hop, and the relay transmits in the second hop. Each hop occupies one time slot. The relay is half-duplex, and capable of decoding the message on a particular subcarrier in one time slot, and re-encoding and forwarding it on a different subcarrier in the next time slot. Thus each message is transmitted on a pair of subcarriers in two hops. It is assumed that the destination is capable of combining the signals from the source and the relay pertaining to the same message. The goal is to maximize the weighted sum rate of the system by jointly optimizing subcarrier pairing and power allocation on each subcarrier in each hop. Both total and individual power constraints for the source and the relay are investigated. For the situations where the relay does not transmit on some subcarriers because doing so ...

  3. A Compact Printed Slot Antenna with High Out-of-band Rejection for WLAN/WiMAX Applications

    Directory of Open Access Journals (Sweden)

    P. Moeikham

    2016-12-01

    Full Text Available The suppression of electromagnetic interferences (EMIs caused by the out-of-band operation is required for broadband antennas. To achieve this purpose, a compact broadband printed slot antenna with build-in filters for band notching is presented. The filters, including I-shaped and inverse L-shaped narrow slits and an L-shaped conductor strip, whose lengths correspond to half wavelengths, were integrated in the proposed antenna structure. The mitigation of the EMIs at the frequency ranges of 2.7 to 3.2 GHz, 4.1 to 4.7 GHz, and over 6.1 GHz was obtained. The proposed antenna capably operated at WLAN/WiMAX frequency ranges of 2.26 to 2.68 GHz, 3.28 to 4.09 GHz, and 4.75 to 6.04 GHz. The nearly omni-directional and likely bi- directional radiation patterns were given by the proposed antenna in xz and yz planes, respectively. Therefore, this antenna is suitable for various WLAN/WiMAX applications.

  4. Full-Duplex Relaying with Improper Gaussian Signaling over Nakagami-m Fading Channels

    KAUST Repository

    Gaafar, Mohamed

    2017-10-04

    We study the potential employment of improper Gaussian signaling (IGS) in full-duplex relaying (FDR) with non-negligible residual self-interference (RSI) under Nakagami- m fading. IGS is recently shown to outperform traditional proper Gaussian signaling (PGS) in several interference-limited settings. In this work, IGS is employed as an attempt to alleviate RSI. We use two performance metrics, namely, the outage probability and the ergodic rate. First, we provide upper and lower bounds for the system performance in terms of the relay transmit power and circularity coefficient, a measure of the signal impropriety. Then, we numerically optimize the relay signal parameters based only on the channel statistics to improve the system performance. Based on the analysis, IGS allows FDR to operate even with high RSI. The results show that IGS can leverage higher power budgets to enhance the performance, meanwhile it relieves RSI impact via tuning the signal impropriety. Interestingly, one-dimensional optimization of the circularity coefficient, with maximum relay power, offers a similar performance as the joint optimization, which reduces the optimization complexity. From a throughput standpoint, it is shown that IGS-FDR can outperform not only PGS-FDR, but also half-duplex relaying with/without maximum ratio combining over certain regions of the target source rate.

  5. Double-layer video transmission over decode-and-forward wireless relay networks using hierarchical modulation.

    Science.gov (United States)

    Nguyen, Tu V; Cosman, Pamela C; Milstein, Laurence B

    2014-04-01

    We consider a wireless relay network with a single source, a single destination, and a multiple relay. The relays are half-duplex and use the decode-and-forward protocol. The transmit source is a layered video bitstream, which can be partitioned into two layers, a base layer (BL) and an enhancement layer (EL), where the BL is more important than the EL in terms of the source distortion. The source broadcasts both layers to the relays and the destination using hierarchical 16-QAM. Each relay detects and transmits successfully decoded layers to the destination using either hierarchical 16-QAM or QPSK. The destination can thus receive multiple signals, each of which can include either only the BL or both the BL and the EL. We derive the optimal linear combining method at the destination, where the uncoded bit error rate is minimized. We also present a suboptimal combining method with a closed-form solution, which performs very close to the optimal. We use the proposed double-layer transmission scheme with our combining methods for transmitting layered video bitstreams. Numerical results show that the double-layer scheme can gain 2-2.5 dB in channel signal-to-noise ratio or 5-7 dB in video peak signal-to-noise ratio, compared with the classical single-layer scheme using conventional modulation.

  6. 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.

  7. On the Feedback Reduction of Relay Multiuser Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil

    2016-01-29

    This paper presents a comprehensive performance analysis of full-duplex multiuser relay networks employing opportunistic scheduling with noisy and compressive feedback. Specifically, two feedback techniques based on compressive sensing (CS) theory are introduced and their effect on the system performance is analyzed. The problem of joint user identity and signal-tonoise ratio (SNR) estimation at the base-station is casted as a block sparse signal recovery problem in CS. Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated using the best linear unbiased estimator (BLUE). To minimize the effect of feedback noise on the estimated SNRs, a back-off strategy that optimally backs-off on the noisy estimated SNRs is introduced, and the error covariance matrix of the noise after CS recovery is derived. Finally, closed-form expressions for the end-to-end SNRs of the system are derived. Numerical results show that the proposed techniques drastically reduce the feedback air-time and achieve a rate close to that obtained by scheduling techniques that require dedicated error-free feedback from all network users. Key findings of this paper suggest that the choice of half-duplex or full-duplex SNR feedback is dependent on the channel coherence interval, and on low coherence intervals, full-duplex feedback is superior to the interference-free half-duplex feedback.

  8. Efficient Cooperative Protocols for Full-Duplex Relaying over Nakagami-m Fading Channels

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-02-24

    In this work, efficient protocols are studied for full-duplex relaying (FDR) with loopback interference over Nakagami-m block fading channels. Recently, a selective decodeand- forward (DF) protocol was proposed for FDR, and was shown to outperform existing protocols in terms of outage over Rayleigh-fading channels. In this work, we propose an incremental selective DF protocol that offers additional power savings, yet yields the same outage performance. We evaluate their outage performance over independent non-identically distributed Nakagami-m fading links, and study their relative performance in terms of the signal-to-noise ratio cumulative distribution function via closed-form expressions. The offered diversity gain is also derived. In addition, we study their performance relative to their half-duplex counterparts, as well as known non-selective FDR protocols. We corroborate our theoretical results with simulation, and confirm that selective cooperation protocols outperform the known non-selective protocols in terms of outage. Finally, we show that depending on the loopback interference level, the proposed protocols can outperform their half-duplex counterparts when high spectral efficiencies are targeted.

  9. 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...

  10. Relay in translation

    OpenAIRE

    Cay Dollerup

    2008-01-01

    This article focuses on the phenomenon of relay in translation. Relay is by nature difficult to discuss and therefore it is no surprise that even scholars who know of its existence usually do so only in passing. Scholars unaware of relay occasionally come across a relayed translation (namely a translation using a first translation from the language of the original as a relay). When they do so in comparative studies, they tend to consider the relayed rendition as either a poor or heavily manip...

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. Relay in translation

    Directory of Open Access Journals (Sweden)

    Cay Dollerup

    2008-01-01

    Full Text Available This article focuses on the phenomenon of relay in translation. Relay is by nature difficult to discuss and therefore it is no surprise that even scholars who know of its existence usually do so only in passing. Scholars unaware of relay occasionally come across a relayed translation (namely a translation using a first translation from the language of the original as a relay. When they do so in comparative studies, they tend to consider the relayed rendition as either a poor or heavily manipulated translation. Historically, relay has been an important factor in translational activity. It is obscured by e.g. the delay in the spread of ‘international fame’ of prominent writers in the past as well as the fact that not all translators and publishers informed audiences that the translation they published was based on a translation from another language than that of the original text. The article attempts to differentiate ‘relayed translations’ from other types of non-direct translation. It discusses their occurrence in translation, interpreting, and subtitling, and ends with a few comments on how relay can(not be tackled in practical translation work.

  16. 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

  17. Spectrum Sharing between Cooperative Relay and Ad-hoc Networks: Dynamic Transmissions under Computation and Signaling Limitations

    CERN Document Server

    Sun, Yin; Li, Yunzhou; Zhou, Shidong; Xu, Xibin

    2010-01-01

    This paper studies a spectrum sharing scenario between an uplink cognitive relay network (CRN) and some nearby low power ad-hoc networks. In particular, the dynamic resource allocation of the CRN is analyzed, which aims to minimize the average interfering time with the ad-hoc networks subject to a minimal average uplink throughput constraint. A long term average rate formula is considered, which is achieved by a half-duplex decode-and-forward (DF) relay strategy with multi-channel transmissions. Both the source and relay are allowed to queue their data, by which they can adjust the transmission rates flexibly based on sensing and predicting the channel state and ad-hoc traffic. The dynamic resource allocation of the CRN is formulated as a non-convex stochastic optimization problem. By carefully analyzing the optimal transmission time scheduling, it is reduced to a stochastic convex optimization problem and solved by the dual optimization method. The signaling and computation processes are designed carefully t...

  18. Ready, steady… relay!

    CERN Multimedia

    2008-01-01

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

  19. Torch Relay Route Unveiled

    National Research Council Canada - National Science Library

    Li Li

    2007-01-01

      Beijing Olympics organizers have announced an ambitious torch relay plan for the 2008 Games which will see the sacred flame reach the world's highest peak and travel through 135 cities around the world...

  20. 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.

  1. 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.   

  2. Simulation of Numerical Distance Relays

    OpenAIRE

    Sherwali, Hamid; Abdlrahem, Abdlmnam

    2010-01-01

    As modern numerical relays are widely employed in protection systems nowadays and modeling of these types of relays is important to adjust and settle protection equipment in electrical facilities and to train protection personnel, the simulation of distance relays using MATLAB offers a good opportunity to perform these activities efficiently and with minimum cost. Another advantages is that, as MATLAB is a powerful tool rich with component models, any shape of relay characteristic (Impedance,...

  3. 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...

  4. 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.

  5. 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.

  6. Laser Communications Relay Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Laser Communications Relay Demonstration project will advance optical communications technology, expanding industry’s capability to produce competitive,...

  7. 49 CFR 234.263 - Relays.

    Science.gov (United States)

    2010-10-01

    .... (b)(1) Alternating current vane type relays, direct current polar type relays, and relays with soft iron magnetic structure shall be tested at least once every two years. (2) Alternating current...

  8. 47th Relay Race!

    CERN Multimedia

    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...

  9. 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.  

  10. CERN Relay Race

    CERN Multimedia

    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.

  11. Radio Relays Improve Wireless Products

    Science.gov (United States)

    2009-01-01

    Signal Hill, California-based XCOM Wireless Inc. developed radio frequency micromachine (RF MEMS) relays with a Phase II Small Business Innovation Research (SBIR) contract through NASA?s Jet Propulsion Laboratory. In order to improve satellite communication systems, XCOM produced wireless RF MEMS relays and tunable capacitors that use metal-to-metal contact and have the potential to outperform most semiconductor technologies while using less power. These relays are used in high-frequency test equipment and instrumentation, where increased speed can mean significant cost savings. Applications now also include mainstream wireless applications and greatly improved tactical radios.

  12. 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...

  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. 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....

  15. 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 ...

  16. 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 ...

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Performance analysis of opportunistic nonregenerative relaying

    KAUST Repository

    Tourki, Kamel

    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.

  2. The Binary-Symmetric Parallel-Relay Network

    CERN Document Server

    Ong, Lawrence; Kellett, Christopher M

    2010-01-01

    We present capacity results of the binary-symmetric parallel-relay network, where there is one source, one destination, and K relays in parallel. We show that forwarding relays, where the relays merely transmit their received signals, achieve the capacity in two ways: with coded transmission at the source and a finite number of relays, or uncoded transmission at the source and a sufficiently large number of relays. On the other hand, decoding relays, where the relays decode the source message, re-encode, and forward it to the destination, achieve the capacity when the number of relays is small.

  3. Technological advance in relay protection: dangerous tendencies

    OpenAIRE

    V.I. Gurevich

    2012-01-01

    In the article, the modern lines in the development of relay protection are considered: complication, increasing number of functions, use of non-determined and free-programmed logic, use of Ethernet and Wi-Fi communications channels, decreasing reliability. The article highlights the danger of the existing tendencies in relay protection development and the necessity for creation of new lines of relay protection that are independent of the current developers and manufacturers. The article call...

  4. 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.

  5. Protective relaying theory and applications

    CERN Document Server

    Elmore, Walter A

    2003-01-01

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

  6. 76 FR 72124 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2011-11-22

    ...] Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal Communications Commission. ACTION... collection associated with the Commission's Internet- Based Telecommunications Relay Service Numbering... notice as an announcement of the effective date of the rules. See Internet-Based Telecommunications Relay...

  7. 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.

  8. Evolution of a Radio Communication Relay System

    Science.gov (United States)

    2013-05-01

    includes two ruggedized relay nodes, to be carried and deployed using deployment forks attached to the flippers of the robots, end-point radios for the...connect to and disconnect from the robot flipper with the use of a quick-release pin. An angular attachment offset between the forks allows the relay

  9. 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.

  10. 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.

  11. 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.

  12. Evolution of a radio communication relay system

    Science.gov (United States)

    Nguyen, Hoa G.; Pezeshkian, Narek; Hart, Abraham; Burmeister, Aaron; Holz, Kevin; Neff, Joseph; Roth, Leif

    2013-05-01

    Providing long-distance non-line-of-sight control for unmanned ground robots has long been recognized as a problem, considering the nature of the required high-bandwidth radio links. In the early 2000s, the DARPA Mobile Autonomous Robot Software (MARS) program funded the Space and Naval Warfare Systems Center (SSC) Pacific to demonstrate a capability for autonomous mobile communication relaying on a number of Pioneer laboratory robots. This effort also resulted in the development of ad hoc networking radios and software that were later leveraged in the development of a more practical and logistically simpler system, the Automatically Deployed Communication Relays (ADCR). Funded by the Joint Ground Robotics Enterprise and internally by SSC Pacific, several generations of ADCR systems introduced increasingly more capable hardware and software for automatic maintenance of communication links through deployment of static relay nodes from mobile robots. This capability was finally tapped in 2010 to fulfill an urgent need from theater. 243 kits of ruggedized, robot-deployable communication relays were produced and sent to Afghanistan to extend the range of EOD and tactical ground robots in 2012. This paper provides a summary of the evolution of the radio relay technology at SSC Pacific, and then focuses on the latest two stages, the Manually-Deployed Communication Relays and the latest effort to automate the deployment of these ruggedized and fielded relay nodes.

  13. A NEW RELAY DESIGN FOR REACTIVE POWER COMPENSATION AND ECONOMICAL COMPARISION WITH CLASSICAL RELAY

    Directory of Open Access Journals (Sweden)

    Mustafa ŞEKKELİ

    2007-02-01

    Full Text Available In most cases, reactive power compensation is otomatically achieved with reactive power control relay by switching on and off, stationary shunt capasitors to the electrical network. İn this study , a new relay has been designed and developed. İn this method, capasitors which is switched on and of are optimally choosen. İn classical relay , only one capasitor can be added or extructed to the network. But,in designing new relay, 1,2 or 3 capasitor banks which are nearest value for desired inductive reactive power can be optimally choosen. As a result , switching number of capacitor and contactor is reduced minimum value and line is loaded less inductive current , it means that less active power losses. New designed relay has been compared with classical one economically . This relay has been manufactured and approved experimantally.

  14. 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)

  15. 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.

  16. Modeling study of the ABS relay valve

    Science.gov (United States)

    Lei, Ming; Lin, Min; Guo, Bin; Luo, Zai; Xu, Weidong

    2011-05-01

    The ABS (anti-lock braking system) relay valve is the key component of anti-lock braking system in most commercial vehicles such as trucks, tractor-trailers, etc. In this paper, structure of ABS relay valve and its work theory were analyzed. Then a mathematical model of ABS relay valve, which was investigated by dividing into electronic part, magnetic part, pneumatic part and mechanical part, was set up. The displacement of spools and the response of pressure increasing, holding, releasing of ABS relay valve were simulated and analyzed under conditions of control pressure 500 KPa, braking pressure 600 KPa, atmospheric pressure 100 KPa and air temperature 310 K. Thisarticle provides reliable theory for improving the performance and efficiency of anti-lock braking system of vehicles.

  17. 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...

  18. 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.

  19. 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.

  20. 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 ...

  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. 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.

  3. 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....

  4. 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.

  5. On Cooperative Relay in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Donglin Hu

    2013-12-01

    Full Text Available Cognitive radios (CR and cooperative communications represent new paradigms that both can effectively improve the spectrum efficiency of future wireless networks. In this paper, we investigate the problem of cooperative relay in CR networks for further enhanced network performance. We investigate how to effectively integrate these two advanced wireless communications technologies. In particular, we focus on the two representative cooperative relay strategies, decode-and-forward (DF and amplify-and-forward (AF, and develop optimal spectrum sensing and p-Persistent CSMA for spectrum access.We develop an analysis for the comparison of these two relay strategies in the context of CR networks, and derive closed-form expressions for network-wide throughput achieved by DF, AF and direct link transmissions. Our analysis is validated by simulations. We find each of the strategies performs better in a certain parameter range; there is no case of dominance for the two strategies. The significant gaps between the cooperative relay results and the direct link results exemplify the diversity gain achieved by cooperative relays in CR networks.

  6. Distance relay performance in future converter dominated power systems

    DEFF Research Database (Denmark)

    Sarkar, Moumita; Jia, Jundi; Yang, Guangya

    2017-01-01

    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...

  7. Relay-supporting Archives: Requirements and Progress

    Directory of Open Access Journals (Sweden)

    Greg Janée

    2009-06-01

    Full Text Available Normal 0 We characterize long-term preservation of digital content as an extended relay in time, in which repeated handoffs of information occur independently at every architectural layer: at the physical layer, where bits are handed off between storage systems; at the logical layer, where digital objects are handed off between repository systems; and at the administrative layer, where collections of objects and relationships are handed off between archives, curators, and institutions.  We examine the support of current preservation technologies for these handoffs, note shortcomings, and argue that some modest improvements would result in a "relay-supporting" preservation infrastructure, one that provides a baseline level of preservation by mitigating the risk of fundamental information loss.  Finally, we propose a series of tests to validate a relay-supporting infrastructure, including a second Archive Ingest and Handling Test (AIHT.

  8. Back-up Perlindungan Relay Jarak Zona Kedua oleh Directional Overcurrent Relays dengan Combined Curves

    Directory of Open Access Journals (Sweden)

    Ariq Arsya Nanda

    2017-01-01

    Full Text Available Dalam makalah ini, pendekatan baru untuk simultan pengaturan jarak dan relay arus lebih terarah. Ketika skema perlindungan garis terdiri dari relay jarak dan relay arus lebih terarah pengaturan relay harus dihitung mengingat kedua relay. Terpisah perhitungan estafet akan menyebabkan hilangnya selektivitas. Jika kedua zona waktu pengaturan adalah tetap, penentuan otomatis dari pengaturan bisa menyebabkan situasi yang tidak sesuai, serta  menemukan satu set selektif pengaturan. Jadi zona waktu kedua harus diubah secara manual sampai masalah optimasi layak. Dalam metode ini, yang terbaik pengaturan untuk zona kedua yang membuat selektifitas dalam back-up dengan relay arus dapat menyebabkan waktu yang tidak menguntungkan dari zona kedua. Dalam metode yang diusulkan, bukannya mengubah waktu zona kedua, bentuk directional arus cadangan yang akan dirubah dengan lokasi gangguan dan saat ini. Ide mengatur proteksi rele arus dalam waktu respon pada arus kesalahan yang lebih tinggi dicapai dengan menggunakan perangkat perlindungan yang universal dengan platform perangkat lunak yang dapat memfasilitasi merancang waktu saat kurva karakteristik yang berbeda bentuk. Hasil simulasi menunjukkan efektivitas metode ini yaitu dengan mengkombinasi kurva rele arah arus lebih dengan relay jarak sehingga mendapatkan koordinasi yang tepat.

  9. 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.

  10. 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 of a re...... of a relay system from such diagrams. Safety properties are identified and formalised as LTL formulae. Model checking is finally used to verify that a model satisfies the safety properties. The method is tested for an existing station in Denmark....

  11. 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.

  12. 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

  13. EFFECTS OF THE NUMBER OF RELAY ANTENNAS AND RELAY-POWER ON MIMO PRECODED TWO-WAY RELAYING

    Directory of Open Access Journals (Sweden)

    S.S. Rajeshwari

    2011-06-01

    Full Text Available In this treatise a two-way Amplify and Forward (AF relay-aided system is considered, which employs the so-called Arithmetic Sum of Average Bit Error Rate (ASABER based MIMO precoding technique. The two-way AF relay system is comprised of the pair of transceiver nodes S1 and S2, and the Relay Node (RN R, where each node is equipped with N1, N2 and Nr antennas, respectively. We study the effects of varying Nr for fixed values of N1 and N2, and as well as the effects of having a fixed transmission power at the RN on the achievable ASABER performance. Based on our intensive simulation campaign, we infer that the attainable diversity order is increased approximately by Nr − min (N1, N2, whenever Nr assumes a value higher than min (N1, N2 for fixed N1, N2 values. However, this is observation is only valid for relay power pr ≥ (p1, p2, where p1 and p2 are the transmit power constraints imposed on the sources S1 and S2, respectively. We also observe that the ASABER MIMO precoder’s BER curve exhibits an error floor for pr ≤ (p1, p2.

  14. Adaptive relaying for ground fault protection of a distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M.S.; Sidhu, T.S.; Talukdar, B.K.

    1995-12-31

    With the advent of digital technology and microprocessor-based relays, it is possible to continuously monitor a power network, analyze it in real time, and change the relay settings to those most suitable at that time, thereby achieving improved protection of the network. This approach, known as adaptive relaying, was applied to the Saskatoon distribution network. This paper describes the software modules developed for setting ground fault overcurrent relays in the adaptive relay protection system. The major task in this system was the on-line coordination of relays, as most faults in a distribution system are of the single-phase to ground type and current unbalance due to single-phase loading contributes to the complexity of relay coordination. The modules served for network topology detection, state estimation, fault analysis, and relay setting and coordination. The paper also presents results of a study of the proposed adaptive ground fault protection scheme using a model distribution network.

  15. 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.

  16. 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.

  17. Two-Hop Secure Communication Using an Untrusted Relay

    National Research Council Canada - National Science Library

    He, Xiang; Yener, Aylin

    2009-01-01

    .... 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...

  18. Protocols for Relay-Assisted Free-Space Optical Systems

    CERN Document Server

    Chatzidiamantis, Nestor D; Kriezis, Emmanouil E; Karagiannidis, George K; Schober, Robert

    2011-01-01

    We investigate transmission protocols for relay-assisted free-space optical (FSO) systems, when multiple parallel relays are employed and there is no direct link between the source and the destination. As alternatives to all-active FSO relaying, where all the available relays transmit concurrently, we propose schemes that select only a single relay to participate in the communication between the source and the destination in each transmission slot. This selection is based on the channel state information (CSI) obtained either from all or from some of the FSO links. Thus, the need for synchronizing the relays' transmissions is avoided and the slowly varying nature of the atmospheric channel is exploited. For both relay selection and all-active relaying, novel closed-form expressions for their outage performance are derived, assuming the versatile Gamma-Gamma channel model. Furthermore, based on the derived analytical results, the problem of allocating the optical power resources to the FSO links is addressed, ...

  19. 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.

  20. relay coordination in the protection of radially-connected power

    African Journals Online (AJOL)

    Over travel of the induction disk or solid- state relay after the fault current has been interrupted is provided for by 0.1s. • A safety margin of 0.15s to compensate for possible deviations in calculated fault cur- rents, relay tap selection, relay operating time, and current transformer ratio errors. 2.2.1. Time grading using relays ...

  1. 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...

  2. 77 FR 1039 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2012-01-09

    ... COMMISSION 47 CFR Part 64 Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal... rules that govern access to toll-free numbers by users of Internet- based Telecommunications Relay... an impact on any rules of particular applicability. Subject: Internet-Based Telecommunications Relay...

  3. 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 ma...

  4. 76 FR 18490 - Contributions to the Telecommunications Relay Service Fund

    Science.gov (United States)

    2011-04-04

    ... COMMISSION 47 CFR Parts 1 and 64 Contributions to the Telecommunications Relay Service Fund AGENCY: Federal...- interconnected VoIP service to participate in and contribute to the Telecommunications Relay Services (TRS) Fund... summary of the Commission's Contributions to the Telecommunications Relay Service Fund, Notice of Proposed...

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

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... I = Current flow in line during indicated, fault. LBB = Local Breaker Backup Scheme. T2. = Time delay setting for the operation of the zone 2 element of distance relay. T3. = Time delay setting for the operation of the zone 3 element of distance relay. Z1 PR = Zone 1 element reach of distance relay in primary ...

  6. 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…

  7. Relay cross metathesis reactions of vinylphosphonates

    Directory of Open Access Journals (Sweden)

    Raj K. Malla

    2014-08-01

    Full Text Available Dimethyl (β-substituted vinylphosphonates do not readily undergo cross metathesis reactions with Grubbs catalyst and terminal alkenes. However, the corresponding mono- or diallyl vinylphosphonate esters undergo facile cross metathesis reactions. The improved reactivity is attributed to a relay step in the cross metathesis reaction mechanism.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Implementation Of Solid State Relays For Power System Protection

    Directory of Open Access Journals (Sweden)

    Nidhi Verma

    2015-06-01

    Full Text Available ABSTRACT This paper provides the implementation of solid state relays for enhancement of power system protection. Relays are an essential part of the power systems and are responsible for the control of any overload voltage or current and protection of the devices from these parameters. The main function of the relay is to constantly monitor the parameter to be controlled and if it exceeds the percentage range set by the controller then it sends a signal to the circuit breaker to break the connection and isolate the faulty part. Solid state relays are preferred over mechanical relays and in this paper relay functioning is done with the help of opto-coupler. Controlling of opto- coupler is done with the help of microcontroller. Circuit operates through Zero Voltage Switching leading to reduction in harmonics. The implementation of relay circuit offers minimal delay time which enables better time response for protection.

  14. Joint Uplink and Downlink Relay Selection in Cooperative Cellular Networks

    CERN Document Server

    Yang, Wei; Wu, Gang; Wang, Haifeng; Wang, Ying

    2010-01-01

    We consider relay selection technique in a cooperative cellular network where user terminals act as mobile relays to help the communications between base station (BS) and mobile station (MS). A novel relay selection scheme, called Joint Uplink and Downlink Relay Selection (JUDRS), is proposed in this paper. Specifically, we generalize JUDRS in two key aspects: (i) relay is selected jointly for uplink and downlink, so that the relay selection overhead can be reduced, and (ii) we consider to minimize the weighted total energy consumption of MS, relay and BS by taking into account channel quality and traffic load condition of uplink and downlink. Information theoretic analysis of the diversity-multiplexing tradeoff demonstrates that the proposed scheme achieves full spatial diversity in the quantity of cooperating terminals in this network. And numerical results are provided to further confirm a significant energy efficiency gain of the proposed algorithm comparing to the previous best worse channel selection an...

  15. 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.

  16. Finite-SNR analysis for partial relaying cooperation with channel coding and opportunistic relay selection

    Science.gov (United States)

    Vu, Thang X.; Duhamel, Pierre; Chatzinotas, Symeon; Ottersten, Bjorn

    2017-12-01

    This work studies the performance of a cooperative network which consists of two channel-coded sources, multiple relays, and one destination. To achieve high spectral efficiency, we assume that a single time slot is dedicated to relaying. Conventional network-coded-based cooperation (NCC) selects the best relay which uses network coding to serve the two sources simultaneously. The bit error rate (BER) performance of NCC with channel coding, however, is still unknown. In this paper, we firstly study the BER of NCC via a closed-form expression and analytically show that NCC only achieves diversity of order two regardless of the number of available relays and the channel code. Secondly, we propose a novel partial relaying-based cooperation (PARC) scheme to improve the system diversity in the finite signal-to-noise ratio (SNR) regime. In particular, closed-form expressions for the system BER and diversity order of PARC are derived as a function of the operating SNR value and the minimum distance of the channel code. We analytically show that the proposed PARC achieves full (instantaneous) diversity order in the finite SNR regime, given that an appropriate channel code is used. Finally, numerical results verify our analysis and demonstrate a large SNR gain of PARC over NCC in the SNR region of interest.

  17. 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

  18. Adult Pacific Lamprey Migration in the Lower Columbia River: 2011 Half-Duplex Pit Tag Studies

    Science.gov (United States)

    2012-01-01

    upstream from McNary Dam that included portions of the Snake and upper Columbia rivers, including the unimpounded Hanford Reach. Lampreys generally...1 Introduction Pacific lamprey (Entosphenus tridentatus) is the largest lamprey species in the Columbia and Snake rivers. Pacific...lampreys are anadromous, with parasitic adults spending 1-4 years in the ocean before returning to spawn in freshwater rivers (Beamish 1980; Close et al

  19. Laser Communications Relay Demonstration (LCRD) Update and the Path Towards Optical Relay Operations

    Science.gov (United States)

    Israel, David J.; Edwards, Bernard L.; Staren, John W.

    2017-01-01

    This paper provides a concept for an evolution of NASA's optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (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). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.

  20. Modeling Electromechanical Overcurrent Relays Using Singular Value Decomposition

    Directory of Open Access Journals (Sweden)

    Feng-Jih Wu

    2012-01-01

    Full Text Available This paper presents a practical and effective novel approach to curve fit electromechanical (EM overcurrent (OC relay characteristics. Based on singular value decomposition (SVD, the curves are fitted with equation in state space under modal coordinates. The relationships between transfer function and Markov parameters are adopted in this research to represent the characteristic curves of EM OC relays. This study applies the proposed method to two EM OC relays: the GE IAC51 relay with moderately inverse-time characteristic and the ABB CO-8 relay with inverse-time characteristic. The maximum absolute values of errors of hundreds of sample points taken from four time dial settings (TDS for each relay between the actual characteristic curves and the corresponding values from the curve-fitting equations are within the range of 10 milliseconds. Finally, this study compares the SVD with the adaptive network and fuzzy inference system (ANFIS to demonstrate its accuracy and identification robustness.

  1. Effectiveness of frequency relays on networks with multiple distributed generation

    Directory of Open Access Journals (Sweden)

    A.A.M. Hassan

    2015-05-01

    Full Text Available Distributed generation (DG has gained a vital role in distribution utilities. So, it is important to correctly detect islanding of DG units. Frequency relays are one of the most commonly used loss of mains detection method. However, distribution utilities may be faced by concern related to false operation of these frequency relays. The commercially available frequency relays reported considering standard tight setting. This paper investigates some factors related to relays internal algorithm that contribute to their different operating responses. The factors that will be investigated are frequency measuring techniques, measuring windows, time delays and under voltage interlock function. With the increasing penetration of DG into the network, it is becoming common to have multiple DG units connected at the same network location. Two generators connected at the same location and employing frequency relays with the same setting but different characteristics were simulated. When subjected to the same network disturbances the possible interference between the two relays is analyzed.

  2. 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.

  3. 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.

  4. Power supply devices and systems of relay protection

    CERN Document Server

    Gurevich, Vladimir

    2013-01-01

    Power Supply Devices and Systems of Relay Protection brings relay protection and electrical power engineers a single, concentrated source of information on auxiliary power supply systems and devices. The book also tackles specific problems and solutions of relay protection power supply systems and devices, which are often not dealt with in the literature. The author, an experienced engineer with more than 100 patents, draws on his own experience to offer practical, tested advice to readers. A Guide to Relay Protection Power Supply for Engineers and Technicians The first chapter reviews the ele

  5. 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.

  6. 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.

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

    KAUST Repository

    Hwang, Kyusung

    2011-02-01

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

  8. Laser Communications Relay Demonstration: Introduction for Experimenters

    Science.gov (United States)

    Israel, David J.

    2017-01-01

    This document provides guidance to individuals or groups considering proposing an experiment for the Laser Communications Relay Demonstration (LCRD) Experiment Program. For the purposes of this document, the term experiment refers to both experiments and demonstrations. The documents goals are: (1) to introduce potential experimenters to the LCRD mission, its purpose, and its system architecture; (2) to help them understand the types of experiments that are possible using LCRD; and (3) to provide an overview of the experiment proposal process and explain how and where to obtain further information about making a proposal.

  9. 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...

  10. Joint Source and Relay Precoding Designs for MIMO Two-Way Relaying Based on MSE Criterion

    CERN Document Server

    Wang, Rui

    2011-01-01

    Properly designed precoders can significantly improve the spectral efficiency of multiple-input multiple-output (MIMO) relay systems. In this paper, we investigate joint source and relay precoding design based on the mean-square-error (MSE) criterion in MIMO two-way relay systems, where two multi-antenna source nodes exchange information via a multi-antenna amplify-and-forward relay node. This problem is non-convex and its optimal solution remains unsolved. Aiming to find an efficient way to solve the problem, we first decouple the primal problem into three tractable sub-problems, and then propose an iterative precoding design algorithm based on alternating optimization. The solution to each sub-problem is optimal and unique, thus the convergence of the iterative algorithm is guaranteed. Secondly, we propose a structured precoding design to lower the computational complexity. The proposed precoding structure is able to parallelize the channels in the multiple access (MAC) phase and broadcast (BC) phase. It th...

  11. 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,...

  12. 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.

  13. The Laser Communications Relay Demonstration Experiment Program

    Science.gov (United States)

    Israel, David J.; Edwards, Bernard L.; Moores, John D.; Piazzolla, Sabino; Merritt, Scott

    2017-01-01

    This paper elaborates on the Laser Communications Relay Demonstration (LCRD) Experiment Program, which will engage in a number of pre-determined experiments and also call upon a wide variety of experimenters to test new laser communications technology and techniques, and to gather valuable data. LCRD is a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will test the functionality in various settings and scenarios of optical communications links from a GEO (Geosynchronous Earth Orbit) payload to ground stations in Southern California and Hawaii over a two-year period following launch in 2019. The LCRD investigator team will execute numerous experiments to test critical aspects of laser communications activities over real links and systems, collecting data on the effects of atmospheric turbulence and weather on performance and communications availability. LCRD will also incorporate emulations of target scenarios, including direct-to-Earth (DTE) links from user spacecraft and optical relay providers supporting user spacecraft. To supplement and expand upon the results of these experiments, the project also includes a Guest Experimenters Program, which encourages individuals and groups from government agencies, academia and industry to propose diverse experiment ideas.

  14. 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.

  15. Opportunistic Cognitive Relaying: A Win-Win Spectrum Sharing Scheme

    Directory of Open Access Journals (Sweden)

    Luo Haiyan

    2010-01-01

    Full Text Available A cost-effective spectrum sharing architecture is proposed to enable the legacy noncognitive secondary system to coexist with the primary system. Specifically, we suggest to install a few intermediate nodes, namely, the cognitive relays, to conduct the spectrum sensing and coordinate the spectrum access. To achieve the goal of win-win between primary and secondary systems, the cognitive relay may act as a cooperator for both of them, and an Opportunistic Cognitive Relaying (OCR scheme is specially devised. In this scheme, the cognitive relay opportunistically switches among three different working modes, that is, Relay for Primary Link (RPL, Relay for Secondary Link (RSL, or Relay for Neither of the Links (RNL, respectively, based on the channel-dependent observation of both systems. In addition, the transmit power for cognitive relay and secondary transmitter in each mode are optimally determined by maximizing the transmission rate of secondary system while keeping or even reducing the outage probability of primary system. Simulation results validate the efficiency of the proposed spectrum sharing scheme.

  16. 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.

  17. 77 FR 20553 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2012-04-05

    ... COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... individuals in a timely manner. DATES: This document is effective May 7, 2012, except the modified reporting... Relay Services for Deaf-Blind Individuals, Report and Order, document FCC 11-56, published at 76 FR...

  18. 77 FR 42187 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2012-07-18

    ... COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... Communications and Video Accessibility Act of 2010, Section 105, Relay Services for Deaf-Blind Individuals, Order... Services for Deaf-Blind Individuals, CG Docket No. 10-210. Form Number: N/A. Type of Review: Revision of a...

  19. 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 ...

  20. relay coordination in the protection of radially-connected power

    African Journals Online (AJOL)

    Abstract. 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 effective operation of the rest of the power system. It often happens that a substation feeder relay ...

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

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... ABSTRACT. An indepth study and analysis has been performed on the 330KV transmission protective relay schemes of the National Electric Power Authority. Some of the basic considerations taken into account in the study to optimize the settings on the existing protective relay schemes are presented.

  2. 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

  3. 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.

  4. 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...

  5. 76 FR 59551 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2011-09-27

    ...] Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal Communications Commission. ACTION... to improve assignment of telephone numbers associated with Internet-based Telecommunications Relay...-2898, or via the Internet at http://www.bcpiweb.com . It is also available on the Commission's Web site...

  6. 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.

  7. Demonstration Model of Self Inductance Using Relay Using an ...

    Indian Academy of Sciences (India)

    IAS Admin

    Using an electrical component like a relay, the phenomenon of self inductance can easily be demonstrated to undergraduate students. By wiring simple electrical components like relay, neon bulb and a DC power supply, intermittent back electromotive force (emf) can be generated in the range from. 60 to 100 volt.

  8. 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...

  9. 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...

  10. 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...

  11. Directional Relays for Multi-Hop Cooperative Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    N. Nouri

    2013-09-01

    Full Text Available In this paper, we investigate power allocation and beamforming in a relay assisted cognitive radio (CR network. Our objective is to maximize the performance of the CR network while limiting interference in the direction of the primary users (PUs. In order to achieve these goals, we first consider joint power allocation and beamforming for cognitive nodes in direct links. Then, we propose an optimal power allocation strategy for relay nodes in indirect transmissions. Unlike the conventional cooperative relaying networks, the applied relays are equipped with directional antennas to further reduce the interference to PUs and meet the CR network requirements. The proposed approach employs genetic algorithm (GA to solve the optimization problems. Numerical simulation results illustrate the quality of service (QoS satisfaction in both primary and secondary networks. These results also show that notable improvements are achieved in the system performance if the conventional omni-directional relays are replaced with directional ones.

  12. 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.

  13. 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".

  14. 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! 

  15. 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.

  16. 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.

  17. Satellite data-relay activities in Arizona

    Science.gov (United States)

    Boner, F.C.; Blee, J.W.; Shope, W.G.

    1985-01-01

    The U.S. Geological Survey (USGS) Arizona District collects data from automated streamflow stations for a wide variety of uses. Data from these stations are provided to Federal, State, and local agencies that have a responsibility to issue flood warnings; to generate forecasts of water availability; to monitor flow to insure compliance with treaties and other legal mandates; and to manage reservoirs for hydropower, flood abatement, and municipal and irrigation water supply. In the mid-1970's, the escalation of data collection costs and a need for more timely data led the Arizona District to examine alternatives for remote data acquisition. On the basis of successful data communications experiments with NASA 's Landsat satellite, an operational system for satellite-data relay was developed in 1976 using the National Oceanic and Atmospheric Administrations 's (NOAA) Geostationary Operational Environmental Satellite (GOES). A total of 62 data collection platforms (DCP's) was operated in 1983. Satellite telemetry operations are controlled at the remote data-collection stations by small battery-operated data collection platforms. The DCP 's periodically collect data from the sensors, store the data in computer memory, and at preset times transmit the data to the GOES satellite. The satellite retransmits the data to Earth where a ground-receive station transmits or transfers the data by land communications to the USGS computer in Reston, Virginia, for processing. The satellite relay transfers the data from sensor to computer in minutes; therefore, the data are available to users on a near real-time basis. (Author 's abstract)

  18. 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.

  19. Two-hop Secure Communication Using an Untrusted Relay

    CERN Document Server

    He, Xiang

    2009-01-01

    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 ca...

  20. OFDMA Cellular Networks with Opportunistic Two-Hop Relays

    Directory of Open Access Journals (Sweden)

    Calcev George

    2009-01-01

    Full Text Available We investigate the benefits of two-hop opportunistic relay in time division duplex (TDD OFDMA cellular network configurations. The paper starts with a short analytical model for the two-hop opportunistic relay. The model expresses the probability of finding a suitable relay node in the presence of lognormal fading and it allows the computation of the expected number of out-of-coverage nodes, as well as the end-to-end spectrum efficiency increase due to opportunistic relaying. The paper then presents results for Monte Carlo simulations of opportunistic relay in some realistic scenarios. Specifically, the simulations consider two scenarios. The first scenario uses the propagation model and a wide-area 19-cell configuration specified in 802.16 OFDMA cellular standard evaluation methodologies. In the second scenario, a Manhattan-like 19-cell topology is used. Our simulations show 11% to 33% in throughput increase when the opportunistic relay technology is used. Our results evaluate the benefits of the opportunistic relay in both scenarios in terms of coverage extension and throughput increase.

  1. Power supply risk assessment method for relay protection system faults

    Directory of Open Access Journals (Sweden)

    Tuyou Si

    2016-12-01

    Full Text Available The influence and the potential risk due to hidden faults of a relay protection system on power supply in distribution systems are paid more and more attention to. A probability analysis method is used to analyse fault characteristics and action mechanism of dominant faults, hidden misoperation and non-operation of the relay protection systems, and failure probability model of relay protection system is constructed and simplified. The effects of dominant faults, hidden misoperation and non-operation of the relay protection systems on the reduced power supply load power are analysed, and a probabilistic model for reduced power supply load power is constructed by three parts corresponding to dominant faults, hidden misoperation and non-operation. A probability calculation method of power supply risk occurrence due to hidden faults of relay protecttion system is proposed considering the fault probability of the relay protection systems, the frequency of the hidden faults occurring in operation period, the reduced power supply load power or load power outage, and the connection mode of the in-lines, out-lines and transformers in a substation. The feasibility and applicability of the proposed method for estimation of risk value probability of the relay protection systems is verified by two studied examples.

  2. 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...

  3. Application of ANFIS for Distance Relay Protection in Transmission Line

    National Research Council Canada - National Science Library

    Azriyenni Azriyenni; Mohd Wazir Mustafa

    2015-01-01

    .... There was applied ANFIS for distance relay protection particularly for transmission line. If a fault occurs during the transmission line identification caused by unwanted fault thus the power delivery to the consumer becomes not going well...

  4. Performance analysis of two-way DF relay selection techniques

    Directory of Open Access Journals (Sweden)

    Samer Alabed

    2016-09-01

    Full Text Available This work proposes novel bi-directional dual-relay selection techniques based on Alamouti space-time block coding (STBC using the decode and forward (DF protocol and analyzes their performance. In the proposed techniques, two- and the three-phase relaying schemes are used to perform bi-directional communication between the communicating terminals via two selected single-antenna relays that employ the Alamouti STBC in a distributed fashion to achieve diversity and orthogonalization of the channels and hence improve the reliability of the system and enable the use of a symbol-wise detector. Furthermore, the network coding strategy applied at all relays is not associated with any power wastage for broadcasting data already known at any terminal, resulting in improved overall performance at the terminals. Our simulations confirm the analytical results and show a substantially improved bit error rate (BER performance of our proposed techniques compared with the current state of the art.

  5. Asymmetric Modulation Gains in Network Coded Relay Networks

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2015-01-01

    to enhance data transmission of groups of data packets, generally using some packet-level coding approach. Network coding's recoding capabilities at intermediate nodes make it particularly suitable for the later. This paper's idea falls in between these two research lines. We aim to increase the end......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–end throughput by (i) using network coding to control the use of the relay in an effective manner, and (ii) leveraging asymmetric modulation to enable the source to efficiently allocate its resources. We provide mathematical analysis and a simple optimization mechanism. Numerical results for the case of fading...

  6. TRACK AND FIELD FRESHMEN TECHNIKAL PREPARATION FOR RELAY RACE

    Directory of Open Access Journals (Sweden)

    Nadezhda Egorova

    2012-01-01

    Full Text Available Methods of relay race technical preparation of athletics freshmen in the course of Physical Training classes in higher education institutions on activ game base are represented in this paper.

  7. 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.

  8. 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.

  9. 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.

  10. London 2012 Olympic Torch Relay: look & feel style guide

    OpenAIRE

    2016-01-01

    The guidelines issued by the London Organising Committee of the Olympic Games and Paralympic Games Ltd (“LOCOG”) provide standards, requirements and guidelines for use of the London 2012 Olympic Torch Relay Emblem (the “Emblem”).

  11. 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.

  12. Educational Software Tool for Protection System Engineers. Distance Relay

    Directory of Open Access Journals (Sweden)

    Trujillo-Guajardo L.A.

    2012-04-01

    Full Text Available In this article, a graphical software tool is presented; this tool is based on the education of protection system engineers. The theoretical fundaments used for the design of operation characteristics of distance relays and their algorithms are presented. The software allows the evaluation and analysis of real time events or simulated ones of every stage of design of the distance relay. Some example cases are presented to illustrate the activities that could be done with the graphical software tool developed.

  13. Data Relay Satellites and remote sensing

    Science.gov (United States)

    Kingwell, Jeff

    1988-05-01

    Issues concerning the operation and use of Data Relay Satellites (DRS) are discussed. Advantages of instituting DRS systems include continuous direct access to large amounts of data, frequent contact with satellites for TTC activities, and the ability to initiate global scientific observation to improve weather forecasting. DRS systems would allow for better control of ballistic missles and would reduce costs for commercial information-based business operations. Disadvantages of fully replacing direct transmissions with DRS include the fact that DRS would make present facilities obsolete, would lead to an increased risk of countries being able to obtain access to data of their own territory, could possibly allow operators to control the release of processed information, would use uniform processing techniques that might not meet the needs of every nation, might lead to an increase in the price of obtaining data in order to cover the high cost of implementing a DRS system, and would increase the chance of data loss and service delays if direct downlinking were not used as a backup.

  14. 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...

  15. 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 ...

  16. Secrecy Capacity of a Class of Orthogonal Relay Eavesdropper Channels

    Directory of Open Access Journals (Sweden)

    Vaneet Aggarwal

    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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Two-Way Multi-Antenna Relaying with Simultaneous Wireless Information and Power Transfer

    Directory of Open Access Journals (Sweden)

    Thanaphat Srivantana

    2017-03-01

    Full Text Available In this paper, we propose various kinds of two-way multi-antenna relaying with simultaneous wireless information and power transfer (SWIPT and investigate their performance. Specifically, we first consider a two-way relay network where two single-antenna end nodes communicate with each other through a multi-antenna relay node that is energy constrained. This relay node harvests energy from the two end nodes and use the harvested energy for forwarding their information. Six relaying schemes that support the considered network then build on the power splitting-based relaying and time switching-based relaying protocols. The average bit error rates of these schemes are evaluated and compared by computer simulations considering several network parameters, including the number of relay antennas, power splitting ratio, and energy harvesting time. Such evaluation and comparison provide useful insights into the performance of SWIPT-based two-way multi-antenna relaying.

  3. 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.

  4. Commercialization and Standardization Progress Towards an Optical Communications Earth Relay

    Science.gov (United States)

    Edwards, Bernard L.; Israel, David J.

    2015-01-01

    NASA is planning to launch the next generation of a space based Earth relay in 2025 to join the current Space Network, consisting of Tracking and Data Relay Satellites in space and the corresponding infrastructure on Earth. While the requirements and architecture for that relay satellite are unknown at this time, NASA is investing in communications technologies that could be deployed to provide new communications services. One of those new technologies is optical communications. The Laser Communications Relay Demonstration (LCRD) project, scheduled for launch in 2018 as a hosted payload on a commercial communications satellite, is a critical pathfinder towards NASA providing optical communications services on the next generation space based relay. This paper will describe NASA efforts in the on-going commercialization of optical communications and the development of inter-operability standards. Both are seen as critical to making optical communications a reality on future NASA science and exploration missions. Commercialization is important because NASA would like to eventually be able to simply purchase an entire optical communications terminal from a commercial provider. Inter-operability standards are needed to ensure that optical communications terminals developed by one vendor are compatible with the terminals of another. International standards in optical communications would also allow the space missions of one nation to use the infrastructure of another.

  5. Learning relay start strategies in swimming: What feedback is best?

    Science.gov (United States)

    Fischer, Sebastian; Braun, Claudia; Kibele, Armin

    2017-04-01

    In the past, studies and book recommendations on relay starts in swimming have been predominantly focused on the change-over time (COT) as a performance criterion. Aside from the circular backswing start with parallel foot placement, few studies have analysed differences in the take-off movement including step approaches as well. Although trends could be identified, the results remained still somewhat inconclusive. In contrast, no study has examined as has examined whether a reduction of COT in between wall contact of the income swimmer and the take-off of the outgoing swimmer is an optimal relay start strategy, as advocated by various swimming experts. Therefore, the purpose of this study was to compare two different relay start strategies: offensive strategy minimizing COT and conservative strategy to maximize horizontal peak force (HPF). In this regard, a learning intervention with 24 elite-level swimmers (12 females, 12 male) was conducted to compare both strategies regarding relay start time, HPF and COT. Subjects were randomly assigned to two feedback groups: COT versus HPF at take-off. The results of this study showed a clear advantage for HPF feedback for relay start performance measured by wall contact of the incoming swimmer and head passage at 7.5 m of the outgoing swimmer. In addition, similar reductions in COTs were found in both training groups. In conclusion, swimmers should focus on force production rather than minimizing COT. For the latter, deteriorating consequences for force production must be considered.

  6. 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.

  7. 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.

  8. 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.

  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. Quantum-Dot-Based Telecommunication-Wavelength Quantum Relay

    Science.gov (United States)

    Huwer, J.; Stevenson, R. M.; Skiba-Szymanska, J.; Ward, M. B.; Shields, A. J.; Felle, M.; Farrer, I.; Ritchie, D. A.; Penty, R. V.

    2017-08-01

    The development of quantum relays for long-haul and attack-proof quantum communication networks operating with weak coherent laser pulses requires entangled photon sources at telecommunication wavelengths with intrinsic single-photon emission for most practical implementations. Using a semiconductor quantum dot emitting entangled photon pairs in the telecommunication O band, we demonstrate a quantum relay fulfilling both of these conditions. The system achieves a maximum fidelity of 94.5% for implementation of a standard four-state protocol with input states generated by a laser. We further investigate robustness against frequency detuning of the narrow-band input and perform process tomography of the teleporter, revealing operation for arbitrary pure input states, with an average gate fidelity of 83.6%. The results highlight the potential of semiconductor light sources for compact and robust quantum-relay technology that is compatible with existing communication infrastructures.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Power Allocation and Pricing in Multi-User Relay Networks Using Stackelberg and Bargaining Games

    CERN Document Server

    Cao, Qian; Jing, Yindi

    2012-01-01

    This paper considers a multi-user single-relay wireless network, where the relay gets paid for helping the users forward signals, and the users pay to receive the relay service. We study the relay power allocation and pricing problems, and model the interaction between the users and the relay as a two-level Stackelberg game. In this game, the relay, modeled as the service provider and the leader of the game, sets the relay price to maximize its revenue; while the users are modeled as customers and the followers who buy power from the relay for higher transmission rates. We use a bargaining game to model the negotiation among users to achieve a fair allocation of the relay power. Based on the proposed fair relay power allocation rule, the optimal relay power price that maximizes the relay revenue is derived analytically. Simulation shows that the proposed power allocation scheme achieves higher network sum-rate and relay revenue than the even power allocation. Furthermore, compared with the sum-rate-optimal so...

  17. 75 FR 54040 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-09-03

    ... No. 03-123; DA 10-1235] Telecommunications Relay Services and Speech-to-Speech Services for... waivers of certain Telecommunications Relay Services (TRS) mandatory minimum standards for Video Relay...

  18. 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.

  19. 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...... adaptively, using the buffer at the RS in order to maximize the average system throughput. We consider the general case in which the RS and the BS can have limits on the maximal number of transmitters that can be received over the multiple access channel. In each slot, there are three type possible actions...

  20. 47 CFR 64.606 - VRS and IP Relay provider and TRS program certification.

    Science.gov (United States)

    2010-10-01

    ... Services and Related Customer Premises Equipment for Persons With Disabilities § 64.606 VRS and IP Relay... establishes that its program in no way conflicts with federal law. (2)Requirements for VRS and IP Relay...

  1. Secure Communication for Two-Way Relay Networks with Imperfect CSI

    National Research Council Canada - National Science Library

    Cong Sun; Ke Liu; Dahu Zheng; Wenbao Ai

    2017-01-01

    This paper considers a two-way relay network, where two legitimate users exchange messages through several cooperative relays in the presence of an eavesdropper, and the Channel State Information (CSI...

  2. Peculiarities of the relays intended for operating trip coils of the high-voltage circuit breakers

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2007-01-01

    Full Text Available Parameters of the subminiature electromagnetic relays used as output elements in microprocessor relay protection, do not correspond to technical specifications on these relay protection. The reasons of this discrepancy are analyzed. Contradictions and discrepancies of the international standards in this area are considered. It is shown, that absence of clearness in standards and mistakes in technical specifications of manufacturers of microprocessor protection do not allow estimating correctly technical parameters and lead to decrease in reliability of relay protection.

  3. Hybrid reed: Solid-state devices are a new generation of protective relays

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2007-01-01

    Full Text Available Research and development in the field of electromechanical protective relays has not been conducted for tens of years. Author’s approach allows viewing the problem of re-equipment of relay protection in a new way. In the author’s opinion combination of reed switches with magnetic circuits and semiconductor elements opens new avenues in development of the promising protective relays featuring reliability, simplicity and low cost. Examples of protective relays made with these elements are given below.

  4. The Capacity Region of the Restricted Two-Way Relay Channel with Any Deterministic Uplink

    CERN Document Server

    Ong, Lawrence

    2011-01-01

    This paper considers the two-way relay channel (TWRC) where two users communicate via a relay. For the restricted TWRC where the uplink from the users to the relay is any deterministic function and the downlink from the relay to the users is any arbitrary channel, the capacity region is obtained. The TWRC considered is restricted in the sense that each user can only transmit a function of its message.

  5. Improved Relay Node Placement Algorithm for Wireless Sensor Networks Application in Wind Farm

    DEFF Research Database (Denmark)

    Chen, Qinyin; Hu, Y.; Chen, Zhe

    2013-01-01

    An emergent application of Wireless Sensor Network (WSN) technology is in the area of Wind Farm Monitoring (WFM), in which relays are used to connect sensors. Key problems to solve in WFM include how to balance loads across relay nodes and how to place relay nodes for redundancy and fault...

  6. Development of a Relay Performance Web Tool for the Mars Network

    Science.gov (United States)

    Allard, Daniel A.; Edwards, Charles D.

    2009-01-01

    Modern Mars surface missions rely upon orbiting spacecraft to relay communications to and from Earth systems. An important component of this multi-mission relay process is the collection of relay performance statistics supporting strategic trend analysis and tactical anomaly identification and tracking.

  7. 49 CFR 236.206 - Battery or power supply with respect to relay; location.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Battery or power supply with respect to relay..., AND APPLIANCES Automatic Block Signal Systems Standards § 236.206 Battery or power supply with respect to relay; location. The battery or power supply for each signal control relay circuit, where an open...

  8. Efficient Capacity Computation and Power Optimization for Relay Networks

    CERN Document Server

    Parvaresh, Farzad

    2011-01-01

    The capacity or approximations to capacity of various single-source single-destination relay network models has been characterized in terms of the cut-set upper bound. In principle, a direct computation of this bound requires evaluating the cut capacity over exponentially many cuts. We show that the minimum cut capacity of a relay network under some special assumptions can be cast as a minimization of a submodular function, and as a result, can be computed efficiently. We use this result to show that the capacity, or an approximation to the capacity within a constant gap for the Gaussian, wireless erasure, and Avestimehr-Diggavi-Tse deterministic relay network models can be computed in polynomial time. We present some empirical results showing that computing constant-gap approximations to the capacity of Gaussian relay networks with around 300 nodes can be done in order of minutes. For Gaussian networks, cut-set capacities are also functions of the powers assigned to the nodes. We consider a family of power o...

  9. 76 FR 31261 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2011-05-31

    ... From the Federal Register Online via the Government Publishing Office ] FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... environments shall be considered when determining whether the individual is deaf-blind under clauses (c)(2)(i...

  10. Appendices for: Improper Signaling in Two-Path Relay Channels

    KAUST Repository

    Gaafar, Mohamed

    2016-12-01

    This document contains the appendices for the work in “Improper Signaling in Two-Path Relay Channels,” which is submitted to 2017 IEEE International Conference on Communications (ICC) Workshop on Full-Duplex Communications for Future Wireless Networks, Paris, France.

  11. Reliability of spike and burst firing in thalamocortical relay cells

    NARCIS (Netherlands)

    Zeldenrust, F.; Chameau, P.J.P.; Wadman, W.J.

    2013-01-01

    The reliability and precision of the timing of spikes in a spike train is an important aspect of neuronal coding. We investigated reliability in thalamocortical relay (TCR) cells in the acute slice and also in a Morris-Lecar model with several extensions. A frozen Gaussian noise current,

  12. Mobility Impact on Centralized Selection of Mobile Relays

    DEFF Research Database (Denmark)

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

    2010-01-01

    the path either as direct or two-hop via a mobile relay. The impact of delays in the measurement collection procedure in this scheme is analyzed in comparison to an ideal selection and an always direct scheme. An ns-2 and matlab based simulation framework is used to investigate effects of varying scenario...

  13. From Onions to Shallots: Rewarding Tor Relays with TEARS

    Science.gov (United States)

    2014-07-18

    users. The efficiency of a central bank was improved in LIRA [16], where a crypto- graphic lottery was used to decide when clients could receive...relays, who receive the ability to obtain guaranteed winners to the lottery in exchange for providing service. Unfortunately, probabilistic guessing

  14. Micro-relay technology for energy-efficient integrated circuits

    CERN Document Server

    Kam, Hei

    2015-01-01

    This book describes the design of relay-based circuit systems from device fabrication to circuit micro-architectures. This book is ideal for both device engineers as well as circuit system designers and highlights the importance of co-design across design hierarchies when optimizing system performance (in this case, energy-efficiency). This book is ideal for researchers and engineers focused on semiconductors, integrated circuits, and energy efficient electronics. This book also: ·         Covers microsystem fabrication, MEMS device design, circuit design, circuit micro-architecture, and CAD ·         Describes work previously done in the field and also lays the groundwork and criteria for future energy-efficient device and system design ·         Maximizes reader insights into the design and modeling of micro-relay, micro-relay reliability, integrated circuit design with micro-relays, and more

  15. 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

    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....

  16. 77 FR 16435 - Transmission Relay Loadability Reliability Standard

    Science.gov (United States)

    2012-03-21

    ... protect the electric network from--fault conditions, but do not limit transmission loadability or... congestion costs, and lead to unnecessary transmission expansion in the future to comply with transmission... Energy Regulatory Commission 18 CFR Parts 39 and 40 Transmission Relay Loadability Reliability Standard...

  17. 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.

  18. Spatial organisation and biomass development after relaying of mussel seed

    NARCIS (Netherlands)

    Capelle, J.J.; Wijsman, J.W.M.; Schellekens, T.; Stralen, van M.R.; Herman, P.M.J.; Smaal, A.C.

    2014-01-01

    It is not known whether and by what factors spatial heterogeneity in mussels (Mytilus edulis L.) affects mussel production in human-created mussel beds. In a field experiment, the same number of mussels was relayed on four different areas within plots of the same size, resulting in four treatments

  19. Advanced relay technologies in next generation wireless communications

    CERN Document Server

    Krikidis, Ioannis

    2016-01-01

    This book details the use of the cooperative networks/relaying approach in new and emerging telecommunications technologies such as full-duplex radio, massive multiple-input multiple-output (MIMO), network coding and spatial modulation, and new application areas including visible light communications (VLC), wireless power transfer, and 5G.

  20. 2 Gigahertz Light Route Radio Relay Link between Asmara and ...

    African Journals Online (AJOL)

    In this paper is discussed the general problem involved in the introduclion of a recently installed light capacity radio relay system in the network of the Imperial Board of Telecommunications of Ethiopia. An outline of the factors governing the choice of appropriate systems and reasons for selecting microwave is given.

  1. Spacecraft Orbits for Earth/Mars-Lander Radio Relay

    Science.gov (United States)

    Noreen, Gary; Diehl, Roger; Neelon, Joseph

    2004-01-01

    A report discusses a network of spacecraft, in orbit around Mars, used to relay radio communications between Earth stations and mobile exploratory robots (rovers) as well as stationary scientific instruments that have been landed on the Mars surface. The relay spacecraft include two already in orbit plus several others planned to arrive at Mars in the years 2004 through 2008. A major portion of the report is devoted to the orbit of the G. Macroni Orbiter, which is in the midst of an iterative design process and is intended to be the first Mars orbiter designed primarily for radio relay. Candidate orbits are analyzed with a view toward choosing one that maximizes the amount of time available for communication with surface units, taking account of visibility as a function of position, the limit on communication distance at low power, and the fact that surface units can transmit more easily when they are in sunlight. Two promising new orbits for Mars relay satellites are identified: a 1/2-sol apoapsis-at-constant-time-of-day equatorial orbit and a 1/4-sol apoapsis-at-constant-time-of-day, critical-inclination orbit.

  2. London 2012 Olympic Torch Relay style guide for licensees

    OpenAIRE

    2015-01-01

    The guidelines issued by the London Organising Committee of the Olympic Games and Paralympic Games Ltd (“LOCOG”) provide standards, requirements and guidelines for use of the London 2012 Olympic Torch Relay Emblem (the “Emblem”), by authorised licensees only.

  3. CERN’s annual relay a runaway success

    CERN Multimedia

    Klaus Hanke for the CERN Running Club

    2016-01-01

    With a record participation of 128 teams of six runners each, this year’s CERN Relay Race took place on 19 May on the Meyrin site.   One of the many winning teams from the 2016 relay race. (Image: Sophia Bennett/CERN) With a record participation of 128 teams and 768 runners, this year’s CERN Relay Race took place on 19 May on the Meyrin site. The teams were mainly composed of CERN staff or contractors working on the CERN site.  A few external teams took also part in the race. Times ranged from 10 min 19 s to over 18 min. The Running Club website now has both the results, and the photos from race day. The CERN Relay Race is jointly organised every year by the CERN Running Club and the Staff Association. It is a tradition that is appreciated by many as a team building, rather than a competitive event. The CERN Running Club wishes to thank all runners and all volunteers for making this event a success.

  4. 77 FR 43538 - Misuse of Internet Protocol (IP) Relay Service; Telecommunications Relay Services and Speech-to...

    Science.gov (United States)

    2012-07-25

    ... Communications Commission. ACTION: Final rule. SUMMARY: In this document, the Commission adopts a measure that... made via IP Relay, including requirements for user registration and rule changes that would permit... users, without unduly burdening legitimate Internet-based TRS consumers seeking to obtain ten-digit...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. An Optimal Coding Strategy for the Binary Multi-Way Relay Channel

    CERN Document Server

    Ong, Lawrence; Kellett, Christopher M; 10.1109/LCOMM.2010.04.092427

    2010-01-01

    We derive the capacity of the binary multi-way relay channel, in which multiple users exchange messages at a common rate through a relay. The capacity is achieved using a novel functional-decode-forward coding strategy. In the functional-decode-forward coding strategy, the relay decodes functions of the users' messages without needing to decode individual messages. The functions to be decoded by the relay are defined such that when the relay broadcasts the functions back to the users, every user is able to decode the messages of all other users.

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

    KAUST Repository

    Zhu, Bingcheng

    2015-05-19

    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 of various geometric shapes, and place the relay nodes in specified available regions. When the number of relay nodes is large, the searching space can grow exponentially, and thus, a grouping optimization technique is proposed to reduce the searching time. We numerically demonstrate that the grouping optimization can provide suboptimal solutions close to the optimal solutions, but the average searching time linearly grows with the number of relay nodes. Two useful theorems are presented to reveal insights into the optimal relay locations. Simulation results show that our proposed optimization framework can effectively provide desirable solution to the problem of optimal relay nodes placement. © 2015 IEEE.

  9. 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.

  10. 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....

  11. 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.

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

    KAUST Repository

    Zhong, Caijun

    2011-06-01

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

  13. Simulation of Distance Relay for Load Encroachment Alleviation with Agent Based Supervision of Zone3

    Directory of Open Access Journals (Sweden)

    Mohamed Badr

    2017-03-01

    Full Text Available Cascaded tripping of power lines due to mal-operation of zone-3 distance relays has been one of the main causes of many previous blackouts worldwide. Encroachment of load into zone-3 characteristics during stressed system operation conditions is a basic factor for such mal-operation of the relays. By improving the operation of zone-3, it is possible to prevent mal-operations so that cascaded line tripping can be avoided. For proper study of the behavior of distance relay during faults and load encroachment phenomenon, we must build a model of distance relay, so in this paper a modeling study of distance relay is implemented using MATLAB/Simulink program. However, this model is distinguished from previous models that, examines in detail the third zone of distance relay. Many cases are simulated with changing line loading and fault location to ensure the capability of the relay to detect the fault and thus the maximum load ability limit of distance relay is obtained. In order to prevent cascading events caused by hidden failures in zone-3 relays, agent based relay architectures have been suggested in the recent past. In such architectures each zone-3 relay contains agents that require communication with other agents at various relevant relays in order to distinguish a real zone-3 event from a temporary overload. In this paper, a local master agent is consulted by all zone-3 agents before a tripping decision is made. The master agent maintains a rule base which is updated based on the local topology of the network and real time monitoring of the status of other relays and circuit breakers. Cisco Packet Tracer program is used for running communication network simulations. The result of the simulation indicate that the time estimated to send and receive a packet data unit (PDU message between one relay to anther can satisfy the communication requirement for the proposed scheme with fiber media.

  14. 78 FR 49717 - Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services...

    Science.gov (United States)

    2013-08-15

    ... COMMISSION 47 CFR Part 64 Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services; Telecommunications Relay Services and Speech-to-Speech Services for Individuals With... Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services; Telecommunications Relay...

  15. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems, EMTDC/PSCAD Relays Modelling

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Sztykiel, Michal; Dollerup, Sebastian

    2011-01-01

    Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows creating complex and accurate relay models derived from the original algorithms. Relay models...... can be applied with various systems, allowing obtaining the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP......-simulated and real world generated current signals connected to the relay....

  16. Adaptive relaying for ground fault protection of distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M. S.; Sidhu, T. S.; Talukdar, B. K.

    1995-06-01

    In consequence of the increasing complexity of power distribution networks frequent changes in relay settings to achieve effective protection against ground faults is essential. The principal focus of this paper was adaptive relaying which makes use of digital technology and microprocessors to design systems which can provide protection of complex distribution networks under all operating conditions. Specifically, the paper described software modules that were developed to achieve this capability, developed for the City of Saskatoon`s distribution network. The system provides reliable, fast and selective protection of all components of the distribution system by constantly monitoring all the buses and currents in the circuit by substation computers, which are under the control of a central control computer. In addition to adaptive protection, the system can also provide optimal control of feeder loads, transformers, reactors, and capacitors, cold load pick up and reclosing of circuit breakers and reclosers. 2 refs., 8 figs.

  17. Switched diversity strategies for dual-hop relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2011-04-29

    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 is adopted, wherein single-input single-output antenna configuration is employed. Each of the transmitter and the receiver however employs multiple antennas to improve the overall link performance. Single-phase and two-phase based receive switching strategies are investigated assuming optimum first hop signal-to-noise ratio (SNR). Moreover, the simple scheme in which the switched diversity is applied independently over the two hops is studied using tight upper bounds. Thorough performance comparisons and switching thresholds optimization for the aforementioned strategies are presented. Simulation results are also provided to validate the mathematical development and to verify the numerical computations.

  18. Measurements of the Lunar Gravity Field using a Relay Subsatellite

    Science.gov (United States)

    Namiki, Noriyuki; Hanada, H.; Kawano, N.; Heki, K.; Iwata, T.; Ogawa, M.; Takano, T.

    1998-01-01

    Space and Astronautical Science (ISAS). Two spacecraft, a main orbiter and a relay subsatellite, constitute the SELENE. The SELENE is scheduled to be launched in 2003. After the SELENE is injected into an elliptical polar orbit of 1 00-km periapsis altitude and 2424-km apoapsis altitude, the relay subsatellite is separated from the main orbiter. Then the main orbiter gradually decreases the eccentricity to a circular orbit in which altitude and inclination are 100 km and 950, respectively. When the mission instruments, including a relay subsatellite transponder for the gravity measurement (RSAT), complete global mapping after a nominal I -year period, the propulsion module of the main orbiter is deorbited to land on the Moon. A differential VLBI experiment by two radio sources on the relay subsatellite and the propulsion module (VRAD-1 and 2) continues until the relay subsatellite will fall on to the lunar surface approximately two months later [6]. RSAT Mission: RSAT is a communication subsystem on the relay subsatellite [7] for four-way Doppler tracking among the main orbiter, the relay subsatellite, and the Usuda Deep Space Center of ISAS (UDSC) [8], as well as two-way range and Doppler measurements, between the relay subsatellite and UDSC (Fig. 1). At the same time, the Tracking and Communication Stations (TACS) of NASDA conduct conventional two-way ranging and Doppler observations of the main orbiter when the main orbiter is visible from Earth.

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

    Directory of Open Access Journals (Sweden)

    Dr.Abdul-Sattar H. Jasim

    2012-03-01

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

  20. Capacity Theorems for the AWGN Multi-Way Relay Channel

    CERN Document Server

    Ong, Lawrence; Johnson, Sarah J

    2010-01-01

    The L-user additive white Gaussian noise multi-way relay channel is considered, where multiple users exchange information through a single relay at a common rate. Existing coding strategies, i.e., complete-decode-forward and compress-forward are shown to be bounded away from the cut-set upper bound at high signal-to-noise ratios (SNR). It is known that the gap between the compress-forward rate and the capacity upper bound is a constant at high SNR, and that between the complete-decode-forward rate and the upper bound increases with SNR at high SNR. In this paper, a functional-decode-forward coding strategy is proposed. It is shown that for L >= 3, complete-decode-forward achieves the capacity when SNR = 0 dB. For L=$, functional-decode-forward achieves the capacity asymptotically as SNR increases.

  1. Restrictions on running IRC (Internet Relay Chat) at CERN

    CERN Multimedia

    2005-01-01

    Due to the large number of computer security incidents at CERN where intruders have used IRC (Internet Relay Chat) software to control computers, IRC connections will be blocked in the CERN firewall from 1st February 2005. Personal use of IRC software is not permitted at CERN. Further details of the restrictions on both personal and professional use of IRC are documented at http://cern.ch/security/IRC.

  2. Degrees of Freedom of Asymmetrical Multi-Way Relay Networks

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth

    2011-01-01

    In this paper, we introduce an asymmetrical multi-way relay channel where a base station conveys independent symbols to K different users while receiving independent symbols from the users. In this network, user i Shas Mi antennas (i ∈ [1, ..., K]), the base station has Σi=1K Mi antennas and the ...... with a proposed joint multiple access and broadcast precoding design using the signal space alignment concept....

  3. Relay cropping of spring barley and winter wheat

    OpenAIRE

    Roslon, Ewa

    2003-01-01

    The general objective of this thesis was to investigate various management practices in order to design a relay cropping system of spring barley and winter wheat with high yielding capacity and good weed suppressive capability under Swedish conditions. The work consisted of two greenhouse experiments, one small-scale field experiment and two field experiments. The factors investigated were seed rate of barley and wheat, undersowing time of wheat and timing of nitrogen fertilisation. Wheat see...

  4. Mems Electromagnetic Micro Relays Overview and Design Considerations

    Directory of Open Access Journals (Sweden)

    Zuraini Dahari, Thurai Vinay and Dinesh Sood

    2012-10-01

    Full Text Available Miniature electromagnetic relay matrices capable of switching currents up to one ampere range are  widely used in commercial applications such as instrumentation and telecommunication. Traditionally these devices have been fabricated from a number of discrete components, however in recent years the emergence of Micro Electro Mechanical System (MEMS technology has opened up the possibility for batch fabrication of microrelays at much reduced unit cost. While several electromagnetic microrelay designs have been successfully developed and commercialized for use as individual units, development work on electromagnetic microrelay matrices where individual relays can be selectively switched on and off have been fewer and less successful. Due to inherent limitations of the micromachining processes, significant dimensional and material property variations occur among individual relays in a matrix. These variations severely limit the tolerance window and hence the reliability of operation of the device. After reviewing existing designs of electromagnetic microrelays, a set of desirable design features that would make the electromagnetic microrelay more robust are identified.  A novel design incorporating these features is proposed and preliminary results of ANSYS1 simulation studies are presented.Keywords: MEMS, microrelay and electromagnetic

  5. ATLAS participation to the 36th Annual CERN Relay Race

    CERN Multimedia

    Gagnon, P.

    On May 17, the Annual CERN relay race took place for the 36th time. This is a fun relay race where a team of six runners runs around the CERN site in Meyrin, up and down many hills, to cover the following distances: the first runner runs 1000 m, the second and third runners cover 800 m each, the fourth and fifth runners each have 500 m and finally, the sixth runner covers the last 300 m all the way to the finish line. Each year, serious and occasionnal runners who take this opportunity to make it their only running moment of the year, give it their best to run the 3.9 km loop in times ranging from a mere 10:39.9 for the best team this year to 18:14.3 for the last of the 65 teams that completed the race. Nobody was wasting time at the starting line of the CERN Annual Relay Race. ATLAS was better represented than ever with a record of eight ATLAS teams participating in this race organized by the CERN running club. The names of the ATLAS participants, as well as the team official times are given in the t...

  6. 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.

  7. Cognitive relaying and power allocation under channel state uncertainties

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2013-04-01

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

  8. On the Coverage Extension and Capacity Enhancement of Inband Relay Deployments in LTE-Advanced Networks

    Directory of Open Access Journals (Sweden)

    Abdallah Bou Saleh

    2010-01-01

    Full Text Available Decode-and-forward relaying is a promising enhancement to existing radio access networks and is currently being standardized in 3GPP to be part of the LTE-Advanced release 10. Two inband operation modes of relay nodes are to be supported, namely Type 1 and Type 1b. Relay nodes promise to offer considerable gain for system capacity or coverage depending on the deployment prioritization. However, the performance of relays, as any other radio access point, significantly depends on the propagation characteristics of the deployment environment. Hence, in this paper, we investigate the performance of Type 1 and Type 1b inband relaying within the LTE-Advanced framework in different propagation scenarios in terms of both coverage extension capabilities and capacity enhancements. A comparison between Type 1 and Type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay node deployments. System level simulations show that Type 1 and Type 1b inband relay deployments offer low to very high gains depending on the deployment environment. As well, it is shown that the effect of the relaying overhead is minimal on coverage extension whereas it is more evident on system throughput.

  9. Optimal transmit power allocation for MIMO two-way cognitive relay networks with multiple relays using AF strategy

    KAUST Repository

    Alsharoa, Ahmad M.

    2014-02-01

    In this letter, we consider a multiple-input multiple-output two-way cognitive radio system under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary terminals aims to exchange different messages with each other using multiple relays where each relay employs an amplify-and-forward strategy. The main objective of our work is to maximize the secondary sum rate allowed to share the spectrum with the primary users by respecting a primary user tolerated interference threshold. In this context, we derive an analytical expression of the optimal power allocated to each antenna of the terminals. We then discuss the impact of some system parameters on the performance in the numerical result section. © 2012 IEEE.

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

    KAUST Repository

    Zafar, Ammar

    2013-12-01

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

  11. Precoder Design and Power Allocation for MIMO Cognitive Radio Two-Way Relaying Systems

    KAUST Repository

    Sboui, Lokman

    2016-08-11

    In this paper, we study a multiple-antenna two-way relaying (TWR) cognitive radio (CR) system. A space alignment (SA) technique is adopted by the secondary users (SUs) to avoid interference with the primary users (PUs). We derive the optimal power allocation that maximizes the TWR achievable SU sum- rate while respecting the total power budget and the relay power constraints. We also analyze the case in which the relay is able to optimize its gain matrix structure to enhance the SU sum-rate. In the numerical results, we quantify the sum-rate gain of using the SA in the TWR CR and we show that the SU sum-rate is very limited when the relay power is low or the PU power and its resulting interference are high. In addition, we optimize the relay gain using an iterative algorithm and compare between different relay matrix structures.

  12. 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.

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

    KAUST Repository

    Soury, Hamza

    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.

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

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

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

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

    KAUST Repository

    Yilmaz, Ferkan

    2011-11-01

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

  16. 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.

  17. Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems

    KAUST Repository

    Benkhelifa, Fatma

    2016-01-06

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for the two-hop Multiple-Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with the multiantenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the sourcedestination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) which separate the EH and ID transfer over the power domain and the time domain, respectively.

  18. Simultaneous Wireless Information and Power Transfer for Decode-and-Forward MIMO Relay Communication Systems

    KAUST Repository

    Benkhelifa, Fatma

    2015-05-01

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for a decode-and-forward (DF) multiple-input multiple-output (MIMO) relay system where the relay is an energy harvesting node. We consider the ideal scenario where both the energy harvesting (EH) receiver and information decoding (ID) receiver at the relay have access to the whole received signal and its energy. The relay harvests the energy while receiving the signal from the source and uses the harvested power to forward the signal to the destination. We obtain the optimal precoders at the source and the relay to maximize the achievable throughput rate of the overall link. In the numerical results, the effect of the transmit power at the source and the position of the relay between the source and the destination on the maximum achievable rate are investigated. © 2015 IEEE.

  19. The Optimal Power Assignment for Cooperative Hybrid-ARQ Relaying Protocol

    Science.gov (United States)

    2011-12-01

    HYBRID- ARQ RELAYING PROTOCOL 5a. CONTRACT NUMBER IN HOUSE 5b. GRANT NUMBER FA8750-11-1-0015 5c. PROGRAM ELEMENT NUMBER 62702F 6. AUTHOR(S...sequence for cooperative hybrid automatic-repeat-request (H- ARQ ) relaying protocol over quasi-static Rayleigh fading channels. We try to determine the...the average total power consumption of the cooperative H- ARQ relaying protocol is complicated in general, so we develop first in this work a simple

  20. Quantum-Relay-Assisted Key Distribution over High Photon Loss Channels

    OpenAIRE

    Zhang, An-Ning; Chen, Yu-Ao; Lu, Chao-Yang; Zhou, Xiao-Qi; Zhao, Zhi; ZHANG, QIANG; Yang, Tao; Pan, Jian-Wei

    2005-01-01

    The maximum distance of quantum communication is limited due to the photon loss and detector noise. Exploiting entanglement swapping, quantum relay could offer ways to extend the achievable distance by increasing the signal to noise ratio. In this letter we present an experimental simulation of long distance quantum communication, in which the superiority of quantum relay is demonstrated. Assisted by quantum relay, we greatly extend the distance limit of unconditional secure quantum communica...

  1. Energy Efficient Cooperative Network Coding with Joint Relay Scheduling and Power Allocation

    OpenAIRE

    Qi, Nan; Xiao, Ming; Tsiftsis, Theodoros A.; Skoglund, Mikael; Cao, Phuong L.; Li, Lixin

    2016-01-01

    The energy efficiency (EE) of a multi-user multi-relay system with the maximum diversity network coding (MDNC) is studied. We explicitly find the connection among the outage probability, energy consumption and EE and formulate the maximizing EE problem under the outage probability constraints. Relay scheduling (RS) and power allocation (PA) are applied to schedule the relay states (transmitting, sleeping, \\emph{etc}) and optimize the transmitting power under the practical channel and power co...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  3. The impact of SFCL and SMES integration on the distance relay

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jun, E-mail: JYang@whu.edu.cn [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhang, Liling; Wang, Xinpu; Chen, Lei [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Chen, Yanxia [Beijing Electric Power Research Institute, Beijing 100075 (China)

    2016-11-15

    Highlights: • The impact of SFCL and SMES integration on the circle distance relay is studied. • The detailed models of SFCL and SMES with distance delay are built in MATLAB. • The integration of SFCL and SMES does influence the operation of distance relay. • An improved distance relay to prevent mal-operation is proposed and verified. - Abstract: The superconducting fault current limiter (SFCL) is an ideal short-circuit fault current limiting device that can limit the fault current without any delay and control the voltage drop of the non-fault line. The superconducting magnetic energy storage (SMES) device can exchange the active and reactive power independently, so it is applied broadly to improve power system stability. With SFCL, the low voltage ride-through capability of SMES can be enhanced as well as its MW and MJ capacities. The distance relay is a key electrical apparatus that will trip circuit breakers to protect electrical devices from short circuit faults. Due to the application of SFCL and SMES integration, the voltage and current in power grid will change accordingly, and the operation characteristic of distance relay may be affected. In this paper, the impact of a bridge-type SFCL and SMES integration on the circle distance relay is studied. And simulation results show that the integration of SFCL and SMES does influence the measured impedance of distance relay, which can lead to mal-operation of the circle distance relay. Furthermore, an improved distance relay is proposed and verified.

  4. 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.

  5. New resource allocation scheme for cognitive relay networks with opportunistic access

    KAUST Repository

    Zafar, Ammar

    2012-06-01

    In this paper, a new resource allocation scheme to minimize Symbol Error rate (SER) for relay assisted cognitive radio networks is studied. A cognitive relay network with amplify-and-forward (AF) fixed gain relays and opportunistic access to the licensed spectrum is considered. The SER objective function and the optimization constraints are derived first. The resource allocation algorithm is then derived using the Langrangian multiplier method. Closed form expressions are derived for the source and relay powers and, symbol time. Analytical results show that the optimal power allocation follows an extended water-filling solution. © 2012 IEEE.

  6. 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.

  7. 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.

  8. Susceptibility of modern relay protection: Will protection from cyber attacks help?

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2014-01-01

    Full Text Available Modern trends in relay protection (RP based on the substitution of electromechanical protection relays (EMPR by digital protective relays (DPR have resulted in the emergence of an absolutely new problem, which was not known before. This problem is the possibility of an intentional remote destructive impact (IRDI on relay protection in order to put it out of action or make it perform functions that have nothing to do with the current operational mode of protected electric equipment. Traditional and well-known methods ensuring information safety cannot fully prevent unauthorized actions of RP. The article describes a new way for the problem solution.

  9. 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.

  10. Power Allocation for Amplify-and-Forward Opportunistic Relaying Systems

    Science.gov (United States)

    Hui, Hui; Zhu, Shihua; Lv, Gangming

    In this letter, power allocation methods are devised for Amplify-and-Forward (AF) opportunistic relaying systems aiming at minimizing the outage probability. First, we extend the result on outage probability in [8] and develop an approximate expression to simplify the power allocation problem. A corresponding optimization problem is constructed and proved to be convex. Then an iterative numerical method is proposed to find the optimal power allocation factor. We also propose a near-optimal method which can directly calculate the power allocation factor to reduce computational complexity. Numerical results show that the proposed methods have a similar performance with the ideal one, and outperform equal power allocation significantly with little overhead.

  11. Minimizing Symbol Error Rate for Cognitive Relaying with Opportunistic Access

    KAUST Repository

    Zafar, Ammar

    2012-12-29

    In this paper, we present an optimal resource allocation scheme (ORA) for an all-participate(AP) cognitive relay network that minimizes the symbol error rate (SER). The SER is derived and different constraints are considered on the system. We consider the cases of both individual and global power constraints, individual constraints only and global constraints only. Numerical results show that the ORA scheme outperforms the schemes with direct link only and uniform power allocation (UPA) in terms of minimizing the SER for all three cases of different constraints. Numerical results also show that the individual constraints only case provides the best performance at large signal-to-noise-ratio (SNR).

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

    Directory of Open Access Journals (Sweden)

    Chengwei Zhang

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

  13. 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.

  14. Solar radiation pressure model for the relay satellite of SELENE

    Science.gov (United States)

    Kubo-Oka, T.; Sengoku, A.

    1999-09-01

    A new radiation pressure model of the relay satellite of SELENE has been developed. The shape of the satellite was assumed to be a combination of a regular octagonal pillar and a column. Radiation forces acting on each part of the spacecraft were calculated independently and summed vectorially to obtain the mean acceleration of the satellite center of mass. We incorporated this new radiation pressure model into the orbit analysis software GEODYN-II and simulated the tracking data reduction process of the relay satellite. We compared two models: one is the new radiation pressure model developed in this work and the other a so-called "cannonball model" where the shape of the satellite is assumed to be a sphere. By the analysis of simulated two-way Doppler tracking data, we found that the new radiation pressure model reduces the observation residuals compared to the cannonball model. Moreover, we can decrease errors in the estimated lunar gravity field coefficients significantly by use of the new radiation pressure model.

  15. Speed of light exceeded in 31st CERN Relay

    CERN Multimedia

    2001-01-01

    In the closest-ever finish of the CERN relay race, Florian Marinet (number 54) of the Neutrinos to Gran Sasso team just fails to catch Pierre Maesen of The Shabbys on the line. The AThLetic AceS team (number 76) won the Veterans category by just 3 seconds from long-time participants The Lynx Runners, who didn't leave empty handed. They picked up the cup that is drawn at random. Evidence for new physics? No, simply evidence for faster legs. Only at CERN could the speed of light come third to a team called The Shabbys. But that's exactly what happened on Wednesday 23 May when the team from PS Division lifted the Opitz cup after winning the 31st CERN relay race. The Shabbys sped home in 10 minutes 53 seconds, just 0.3 of a second ahead of the 'Neutrinos to Gran Sasso' team. There's some logic there since it is the PS complex that will provide the protons that will give rise to the neutrino beam. As for 'c0 the speed of light', they took a relatively leisurely 11 minutes 1.6 seconds to cover the course. A total...

  16. CERN Relay Race: No records broken in a bumper year

    CERN Multimedia

    2007-01-01

    Tribute is paid to David Dallman, 20 times the organiser of the CERN Relay Race, who is now retiring.Solve the following mathematical problem for athletes: take the first and third-placed teams in the 2006 CERN Relay Race, randomly mix the runners to form two new teams, and what is the result? Answer: first place and fifth place. In short, the team which has reigned supreme in first place since 2001, the "Shabbys", decided to spice up the race this year by merging with their arch rivals, the "Latinos Volantes", themselves no strangers to the podium. And at the winning line, it was the hybrid formation, "Shabbys Volantes", which took the honours (no surprises there!). Sadly, they were unable to beat the Shabbys’ previous record nor get anywhere near the all-time race record of 10 minutes and 13 seconds for the 3.9-km course, held for a quarter of a century by the "UA1 Strollers". One of the members of that legendary team and race organiser 20 times, David Dallman, mar...

  17. Coded Cooperation for Multiway Relaying in Wireless Sensor Networks.

    Science.gov (United States)

    Si, Zhongwei; Ma, Junyang; Thobaben, Ragnar

    2015-06-29

    Wireless sensor networks have been considered as an enabling technology for constructing smart cities. One important feature of wireless sensor networks is that the sensor nodes collaborate in some manner for communications. In this manuscript, we focus on the model of multiway relaying with full data exchange where each user wants to transmit and receive data to and from all other users in the network. We derive the capacity region for this specific model and propose a coding strategy through coset encoding. To obtain good performance with practical codes, we choose spatially-coupled LDPC (SC-LDPC) codes for the coded cooperation. In particular, for the message broadcasting from the relay, we construct multi-edge-type (MET) SC-LDPC codes by repeatedly applying coset encoding. Due to the capacity-achieving property of the SC-LDPC codes, we prove that the capacity region can theoretically be achieved by the proposed MET SC-LDPC codes. Numerical results with finite node degrees are provided, which show that the achievable rates approach the boundary of the capacity region in both binary erasure channels and additive white Gaussian channels.

  18. Coded Cooperation for Multiway Relaying in Wireless Sensor Networks †

    Science.gov (United States)

    Si, Zhongwei; Ma, Junyang; Thobaben, Ragnar

    2015-01-01

    Wireless sensor networks have been considered as an enabling technology for constructing smart cities. One important feature of wireless sensor networks is that the sensor nodes collaborate in some manner for communications. In this manuscript, we focus on the model of multiway relaying with full data exchange where each user wants to transmit and receive data to and from all other users in the network. We derive the capacity region for this specific model and propose a coding strategy through coset encoding. To obtain good performance with practical codes, we choose spatially-coupled LDPC (SC-LDPC) codes for the coded cooperation. In particular, for the message broadcasting from the relay, we construct multi-edge-type (MET) SC-LDPC codes by repeatedly applying coset encoding. Due to the capacity-achieving property of the SC-LDPC codes, we prove that the capacity region can theoretically be achieved by the proposed MET SC-LDPC codes. Numerical results with finite node degrees are provided, which show that the achievable rates approach the boundary of the capacity region in both binary erasure channels and additive white Gaussian channels. PMID:26131675

  19. Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems

    KAUST Repository

    Benkhelifa, Fatma

    2016-03-28

    © 2015 IEEE. In this paper, we investigate two-hop Multiple- Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with simultaneous wireless information and power transfer (SWIPT) at the multi-antenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the source-destination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. This scheme provides an outer bound for the achievable R-E region since practical energy harvesting circuits are not yet able to harvest the energy and decode the information simultaneously. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) proposed in [1] and which separate the EH and ID transfer over the power domain and the time domain, respectively. In our study, we derive the boundary of the achievable R- E region and we show the effect of the source transmit power, the relay transmit power and the position of the relay between the source and the destination on the achievable R-E region for the ideal scenario and the two practical schemes.

  20. Distributed Generalized Low-Density Codes for Multiple Relay Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Han Changcai

    2008-01-01

    Full Text Available As a class of pseudorandom error correcting codes, generalized low-density (GLD codes exhibit excellent performance over both additive white Gaussian noise (AWGN and Rayleigh fading channels. In this paper, distributed GLD codes are proposed for multiple relay cooperative communications. Specifically, using the partial error detecting and error correcting capabilities of the GLD code, each relay node decodes and forwards some of the constituent codes of the GLD code to cooperatively form a distributed GLD code, which can work effectively and keep a fixed overall code rate when the number of relay nodes varies. Also, at relay nodes, a progressive processing procedure is proposed to reduce the complexity and adapt to the source-relay channel variations. At the destination, the soft information from different paths is combined for the GLD decoder thus diversity gain and coding gain are achieved simultaneously. Simulation results verify that distributed GLD codes with various number of relay nodes can obtain significant performance gains in quasistatic fading channels compared with the strategy without relays and the performance is further improved when more relays are employed.

  1. Distributed Generalized Low-Density Codes for Multiple Relay Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Weiling Wu

    2008-09-01

    Full Text Available As a class of pseudorandom error correcting codes, generalized low-density (GLD codes exhibit excellent performance over both additive white Gaussian noise (AWGN and Rayleigh fading channels. In this paper, distributed GLD codes are proposed for multiple relay cooperative communications. Specifically, using the partial error detecting and error correcting capabilities of the GLD code, each relay node decodes and forwards some of the constituent codes of the GLD code to cooperatively form a distributed GLD code, which can work effectively and keep a fixed overall code rate when the number of relay nodes varies. Also, at relay nodes, a progressive processing procedure is proposed to reduce the complexity and adapt to the source-relay channel variations. At the destination, the soft information from different paths is combined for the GLD decoder thus diversity gain and coding gain are achieved simultaneously. Simulation results verify that distributed GLD codes with various number of relay nodes can obtain significant performance gains in quasistatic fading channels compared with the strategy without relays and the performance is further improved when more relays are employed.

  2. Cultivar and planting date selection for relay-cropping soybean with winter oilseeds

    Science.gov (United States)

    Double- and relay-cropping soybean with winter camelina (Camelina sativa L. Crantz) and pennycress (Thlaspi arvense L.) have been shown to be viable cropping systems for the Upper Midwest. Relaying soybean with these winter oilseeds can result in greater total seed yield (i.e., both combined) and ec...

  3. 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.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    Direct/Relay (CDR) schemes, which involve two flows, of a direct and a relayed user. In this paper we characterize a CDR scheme by deriving/bounding the Diversity-Multiplexing Trade-off (DMT) function. Two cases are considered. In the first case a transmitter knows the Channel State Information (CSI...

  5. Relay-aided multi-cell broadcasting with random network coding

    DEFF Research Database (Denmark)

    Lu, Lu; Sun, Fan; Xiao, Ming

    2010-01-01

    We investigate a relay-aided multi-cell broadcasting system using random network codes, where the focus is on devising efficient scheduling algorithms between relay and base stations. Two scheduling algorithms are proposed based on different feedback strategies; namely, a one-step scheduling...

  6. STUDI ANALISIS SETTING RELAY PENGAMAN DI PENYULANG NGURAH RAI I DAN PENYULANG NGURAH RAI II

    Directory of Open Access Journals (Sweden)

    I Komang Sutarjana

    2015-03-01

    Full Text Available Permasalahan gangguan di jaringan distribusi 20 kV seringkali menyebabkan terputusnya pasokan daya listrik kepada pelanggan. Salah satu penyebab keandalan sistem kurang baik adalah kesalahan koordinasi setting relay pada penyulang. Seperti yang terjadi pada penyulang Ngurah Rai I dan Penyulang Ngurah Rai II dimana terdapat kesalahan koordinasi setting antara relay pada pangkal penyulang yang terletak di Gardu Induk (GI dengan relay pada di ujung jaringan yang terletak di Gardu Hubung (GH. Untuk memecahkan masalah tersebut maka perlu dianalisis setting relay yang sudah ada (eksisting. Untuk membuktikan koordinasi setting relay sudah sempurna, maka akan dilakukan simulasi menggunakan bantuan program computer yaitu Electrical Transient Analysis Program (ETAP. Dari hasil analisis diperoleh nilai setting dimulai dari setting Over Current Relay (OCR pada pangkal penyulang (GI 360 A dan Tms 0,36 sedangkan untuk nilai setting arus OCR pada ujung penyulang (GH yang menggunakan relay directional 330 A dan TMS 0,16. Kemudian untuk setting GFR pada pangkal penyulang (GI diperoleh nilai 34 A dan TMS 0,2. Sedangkan setting GFR pada ujung penyulang (GH yang menggunakan relay directional diperoleh nilai 31 A dan TMS 0,1.

  7. 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.

  8. 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 t...

  9. Reliability of microprocessor-based relay protection devices: Myths and reality

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2009-01-01

    Full Text Available The article examines four basic theses about the ostensibly extremely high reliability of microprocessor-based relay protection (MP touted by supporters of MP. Through detailed analysis based on many references it is shown that the basis of these theses are widespread myths, and actually MP reliability is lower than the reliability of electromechanical and electronic protective relays on discrete components.

  10. Whether and Where to Code in the Wireless Packet Erasure Relay Channel

    DEFF Research Database (Denmark)

    Shi, Xiaomeng; Medard, Muriel; Lucani Rötter, Daniel Enrique

    2013-01-01

    energies. We show that coding at the relay alone while operating in a rateless fashion is neither throughput nor energy efficient. Given a set of system parameters, our analysis determines the optimal amount of time the relay should participate in the transmission, and where coding should be performed....

  11. Light-Actuated Micromechanical Relays for Zero-Power Infrared Detection

    Science.gov (United States)

    2017-03-01

    Light-Actuated Micromechanical Relays for Zero-Power Infrared Detection Zhenyun Qian, Sungho Kang, Vageeswar Rajaram, Cristian Cassella, Nicol E...near-zero power infrared (IR) detection. Differently from any existing switching element, the proposed LMR relies on a plasmonically-enhanced...zero-power sensor; infrared detector; micromechanical relay; switch; plasmonic absorber. Introduction Due to the fast development of the Internet

  12. Robust Relay in Narrow-Band Communications for Ubiquitous IoT Access

    Directory of Open Access Journals (Sweden)

    Qinghe Du

    2017-01-01

    Full Text Available We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN, which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability.

  13. 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...

  14. 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 c...

  15. Error-rate performance analysis of cooperative OFDMA system with decode-and-forward relaying

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-06-01

    In this paper, we investigate the performance of a cooperative orthogonal frequency-division multiple-access (OFDMA) system with decode-and-forward (DaF) relaying. Specifically, we derive a closed-form approximate symbol-error-rate expression and analyze the achievable diversity orders. Depending on the relay location, a diversity order up to (LSkD + 1) + σ M m = 1 min(LSkRm + 1, LR mD + 1) is available, where M is the number of relays, and LS kD + 1, LSkRm + 1, and LRmD + 1 are the lengths of channel impulse responses of source-to-destination, source-to- mth relay, and mth relay-to-destination links, respectively. Monte Carlo simulation results are also presented to confirm the analytical findings. © 2013 IEEE.

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

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

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

  17. On achievable rates of interference and cognitive channels with a relay

    KAUST Repository

    Zorgui, Marwen

    2015-08-30

    We consider a two-user interference channel assisted by a relay. Treating interference as noise at the receivers, and adopting an amplify and forward (AF) strategy at the relay, we derive achievable rates of both users, for given powers. Next, we solve the optimal power allocation problem maximizing the weighted sum rate of both users with and without relay power optimization. In particular, we propose a simple iterative line search algorithm solving the joint optimization problem over the three transmit powers and show that optimizing the relay power enhances the performance of the system. Then, considering the first user as a primary user, we determine the maximum instantaneous rate that the secondary user can achieve subject to an outage constraint with respect to the primary user and a peak power constraint. We show that, likewise the first part, jointly optimizing the secondary user and the relay transmit powers enhances the secondary user performance.

  18. 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.

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

    KAUST Repository

    Ikki, Salama Said

    2010-09-01

    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 with fixed power allocation, and joint optimization of the PA and relay location under total transmit power constraint, in order to minimize the outage probability and average error probability at high signal-to-noise ratios (SNR). Analytical results are validated by numerical simulations and comparisons between the different optimization schemes and their performance are provided. Results show that optimum PA brings only coding gain, while optimum relay location yields, in addition to the latter, diversity gains as well. Also, joint optimization improves both, the diversity gain and coding gain. Furthermore, results illustrate that the analyzed adaptive algorithms outperform uniform schemes. ©2010 IEEE.

  20. Joint Power and Resource Allocation for Block-Fading Relay-Assisted Broadcast Channels

    CERN Document Server

    Shaqfeh, Mohammad

    2012-01-01

    We provide the solution for optimizing the power and resource allocation over block-fading relay-assisted broadcast channels in order to maximize the long term average achievable rates region of the users. The problem formulation assumes regenerative (repetition coding) decode-and-forward (DF) relaying strategy, long-term average total transmitted power constraint, orthogonal multiplexing of the users messages within the channel blocks, possibility to use a direct transmission (DT) mode from the base station to the user terminal directly or a relaying (DF) transmission mode, and partial channel state information. We show that our optimization problem can be transformed into an equivalent "no-relaying" broadcast channel optimization problem with each actual user substituted by two virtual users having different channel qualities and multiplexing weights. The proposed power and resource allocation strategies are expressed in closed-form that can be applied practically in centralized relay-assisted wireless netw...

  1. 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.

  2. Optimal Incentive Pricing on Relaying Services for Maximizing Connection Availability in Multihop Cellular Networks

    Directory of Open Access Journals (Sweden)

    Ming-Hua Lin

    2012-01-01

    Full Text Available This paper investigates an incentive pricing problem for relaying services in multihop cellular networks. Providing incentives to encourage mobile nodes to relay data is a critical factor in building successful multihop cellular networks. Most existing approaches adopt fixed-rate or location-based pricing on rewarding packets forwarding. This study applies a mathematical programming model to determine an optimal incentive price for each intermediate node that provides relaying services. Under the obtained incentive price, the connection availability of the networks is maximized by using the same relaying costs as other pricing schemes. A signomial geometric programming problem is constructed, and a deterministic optimization approach is employed to solve the problem. Besides, quality-of-service constraints are added in the proposed model to mitigate the unfairness between connection availabilities of individual nodes. Computational results demonstrate that the proposed model obtains the optimal incentive price on relaying services to maximize connection availability of the networks.

  3. Detection Performance of M-ary Relay Trees with Non-binary Message Alphabets

    CERN Document Server

    Zhang, Zhenliang; Pezeshki, Ali; Moran, William; Howard, Stephen D

    2012-01-01

    We study the detection performance of $M$-ary relay trees, where only the leaves of the tree represent sensors making measurements. The root of the tree represents the fusion center which makes an overall detection decision. Each of the other nodes is a relay node which aggregates $M$ messages sent by its child nodes into a new compressed message and sends the message to its parent node. Building on previous work on the detection performance of $M$-ary relay trees with binary messages, in this paper we study the case of non-binary relay message alphabets. We characterize the exponent of the error probability with respect to the message alphabet size $\\mathcal D$, showing how the detection performance increases with $\\mathcal D$. Our method involves reducing a tree with non-binary relay messages into an equivalent higher-degree tree with only binary messages.

  4. Exact Outage Performance Analysis of Multiuser Multi-relay Spectrum Sharing Cognitive Networks

    Directory of Open Access Journals (Sweden)

    T. Zhang

    2015-04-01

    Full Text Available In this paper, we investigate the outage performance of dual-hop multiuser multi-relay cognitive radio networks under spectrum sharing constraints. Using an efficient relay-destination selection scheme, the exact and asymptotic closed-form expressions for the outage probability are derived. From these expressions it is indicated that the achieved diversity order is only determined by the number of secondary user (SU relays and destinations, and equals to M+N (where M and N are the number of destination nodes and relay nodes, respectively. Further, we find that the coding gain of the SU network will be affected by the interference threshold $bar I$ at the primary user (PU receiver. Specifically, as the increases of the interference threshold, the coding gain of the considered network approaches to that of the multiuser multi-relay system in the non-cognitive network. Finally, our study is corroborated by representative numerical examples.

  5. Lower Bounds on the Capacity of the Relay Channel with States at the Source

    Directory of Open Access Journals (Sweden)

    Abdellatif Zaidi

    2009-01-01

    Full Text Available We consider a state-dependent three-terminal full-duplex relay channel with the channel states noncausally available at only the source, that is, neither at the relay nor at the destination. This model has application to cooperation over certain wireless channels with asymmetric cognition capabilities and cognitive interference relay channels. We establish lower bounds on the channel capacity for both discrete memoryless (DM and Gaussian cases. For the DM case, the coding scheme for the lower bound uses techniques of rate-splitting at the source, decode-and-forward (DF relaying, and a Gel'fand-Pinsker-like binning scheme. In this coding scheme, the relay decodes only partially the information sent by the source. Due to the rate-splitting, this lower bound is better than the one obtained by assuming that the relay decodes all the information from the source, that is, full-DF. For the Gaussian case, we consider channel models in which each of the relay node and the destination node experiences on its link an additive Gaussian outside interference. We first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. We also discuss a model with correlated interferences. For each of the first two models, we establish a lower bound on the channel capacity. The coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. The results reveal that, by opposition to carbon copying onto dirty paper and its root Costa's initial dirty paper coding (DPC, it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn.

  6. 75 FR 67333 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-11-02

    ...] Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and Speech Disabilities, E911 Requirements for IP-Enabled Service Providers, Internet-Based Telecommunications Relay Service... improve assignment of telephone numbers associated with Internet-based Telecommunications Relay Service (i...

  7. 75 FR 49491 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-08-13

    ... COMMISSION Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and... through June 30, 2011 Interstate Telecommunications Relay Services (TRS) Fund (Fund) year. This action is... summary of the Commission's Telecommunications Relay Services and Speech-to-Speech Services for...

  8. The success of the 45th CERN Relay Race

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    On Thursday, 21 May, 783 people (9 Nordic walkers and 129 teams of 6 runners each) took part in the 45th CERN Relay Race.   The teams were divided into eight different categories: three CERN categories (Seniors, Dames, Mixte) – in which the six runners in the team must belong to the same professional unit – and four “open” categories (Open, Veterans Open, Dames Open, Mixte Open) - in which the six runners in the team do not necessarily belong to the same professional unit and can include people from outside CERN. Each team covered 3,600 metres around the Meyrin site, with the race's fastest runners covering this distance in only 11 minutes and 5 seconds! (See all the results here. For more photos from the event, see here, here and here.)  

  9. Adaptive relaying for ground fault protection of a distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M.S.; Sidhu, T.S.; Talukdar, B.K. [Saskatchewan Univ., Saskatoon, SK (Canada)

    1995-12-31

    Adaptive protection was used for designing a protection system for the City of Saskatoon`s distribution network. The software and hardware were developed and the protection system was implemented in the laboratory at the University of Saskatchewan. In the first phase of the project, phase overcurrent relays were coordinated on the basis of three-phase faults. Most faults in distribution networks were single-phase to ground faults. Ground fault currents varied due to different grounding practices, changes in operating conditions and system topology. In the second phase of the project, adaptive capabilities for ground overcurrent and directional ground overcurrent protection were added. Software modules developed for achieving adaptive ground fault protection were described. Results from system studies carried out using the City of Saskatoon`s distribution network were also analyzed. 7 refs., 8 figs.

  10. 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.

  11. Quinones as Reversible Electron Relays in Artificial Photosynthesis.

    Science.gov (United States)

    Rodenberg, Alexander; Orazietti, Margherita; Mosberger, Mathias; Bachmann, Cyril; Probst, Benjamin; Alberto, Roger; Hamm, Peter

    2016-05-04

    We explore the potential of various hydroquinone/quinone redox couples as electron relays in a homogenous water reduction system between a Re-based photosensitizer and a sacrificial electron donor [tris-(2-carboxyethyl)-phosphine, TCEP]. By using transient IR spectroscopy, flash photolysis as well as stopped-flow techniques covering timescales from picoseconds to 100 ms, we determine quenching rates and cage escape yields, the kinetics of the follow-up chemistry of the semiquinone, the recombination rates, as well as the re-reduction rates by TCEP. The overall quantum yield of hydrogen production is low, and we show that the limiting factors are the small cage escape yields and, more importantly, the slow regeneration rate by TCEP in comparison to the undesired charge recombination with the reduced water reduction catalyst. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Experimental service of 3DTV broadcasting relay in Korea

    Science.gov (United States)

    Hur, Namho; Ahn, Chung-Hyun; Ahn, Chieteuk

    2002-11-01

    This paper introduces 3D HDTV relay broadcasting experiments of 2002 FIFA World Cup Korea/Japan using a terrestrial and satellite network. We have developed 3D HDTV cameras, 3D HDTV video multiplexer/demultiplexer, a 3D HDTV receiver, and a 3D HDTV OB van for field productions. By using a terrestrial and satellite network, we distributed a compressed 3D HDTV signal to predetermined demonstration venues which are approved by host broadcast services (HBS), KirchMedia, and FIFA. In this case, we transmitted a 40Mbps MPEG-2 transport stream (DVB-ASI) over a DS-3 network specified in ITU-T Rec. G.703. The video/audio compression formats are MPEG-2 main-profile, high-level and Dolby Digital AC-3 respectively. Then at venues, the recovered left and right images by the 3D HDTV receiver are displayed on a screen with polarized beam projectors.

  13. Tensile-stressed microelectromechanical apparatus and microelectromechanical relay formed therefrom

    Science.gov (United States)

    Fleming, James G [Albuquerque, NM

    2008-03-04

    A microelectromechanical (MEM) apparatus is disclosed which includes a shuttle suspended above a substrate by two or more sets of tensile-stressed beams which are operatively connected to the shuttle and which can comprise tungsten or a silicon nitride/polysilicon composite structure. Initially, the tensile stress in each set of beams is balanced. However, the tensile stress can be unbalanced by heating one or more of the sets of beams; and this can be used to move the shuttle over a distance of up to several tens of microns. The MEM apparatus can be used to form a MEM relay having relatively high contact and opening forces, and with or without a latching capability.

  14. 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.

  15. The Physical Layer Security Experiments of Cooperative Communication System with Different Relay Behaviors

    Directory of Open Access Journals (Sweden)

    Yishan Su

    2017-04-01

    Full Text Available Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1 to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2 the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3 the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission.

  16. Design of Asymmetrical Relay Resonators for Maximum Efficiency of Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Bo-Hee Choi

    2016-01-01

    Full Text Available This paper presents a new design method of asymmetrical relay resonators for maximum wireless power transfer. A new design method for relay resonators is demanded because maximum power transfer efficiency (PTE is not obtained at the resonant frequency of unit resonator. The maximum PTE for relay resonators is obtained at the different resonances of unit resonator. The optimum design of asymmetrical relay is conducted by both the optimum placement and the optimum capacitance of resonators. The optimum placement is found by scanning the positions of the relays and optimum capacitance can be found by using genetic algorithm (GA. The PTEs are enhanced when capacitance is optimally designed by GA according to the position of relays, respectively, and then maximum efficiency is obtained at the optimum placement of relays. The capacitance of the second resonator to nth resonator and the load resistance should be determined for maximum efficiency while the capacitance of the first resonator and the source resistance are obtained for the impedance matching. The simulated and measured results are in good agreement.

  17. Development and testing of a relay nozzle concept for air-jet weaving

    Science.gov (United States)

    Münkel, A.; Gloy, Y. S.; Gries, T.

    2017-10-01

    The textile industry is an energy intensive branch of industry. Increasing energy costs are a challenge for textile manufacturers as well as for the developers of textile production machines [1]. Air jet weaving is the most productive method to produce woven fabrics. However, air-jet weaving machines have a significantly higher level of energy consumption compared to other weaving machines. Approximately 80% of compressed air is consumed by the relay nozzles. Therefore, there are different approaches to reduce the consumption of compressed air and to increase the energy efficiency of air-jet looms [2] At the Institut für Textiltechnik der RWTH Aachen University, Aachen new relay nozzle concepts have been developed. Based on Computational Fluid Dynamics (CFD) the concepts were further developed with the result of an energy-efficient relay nozzle concept. The simulations have shown the potential energy savings up to 60 % compared to conventional relay nozzles. Furthermore, practical validations of these simulation results were done. The velocity, stagnation pressure and volume flow were measured in the reed canal. The optimal position regarding the injection angle and high, as well as the distance between two relay nozzles were identified with the results of the measurements. In addition, the relay nozzles were tested in the industrial environment. These tests have shown a low error rate which is comparable conventional relay nozzle concepts. Furthermore, exergy savings up to 49% has been measured.

  18. Optimization of beamforming and path planning for UAV-assisted wireless relay networks

    Directory of Open Access Journals (Sweden)

    Ouyang Jian

    2014-04-01

    Full Text Available Recently, unmanned aerial vehicles (UAVs acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifically, in the scenario where the access point (AP is mobile, a UAV needs to find an efficient path to guarantee the connectivity of the relay link. Motivated by this fact, this paper proposes an optimal design for beamforming (BF and UAV path planning. First of all, we study a dual-hop amplify-and-forward (AF wireless relay network, in which a UAV is used as relay between a mobile AP and a fixed base station (BS. In the network, both of the AP and the BS are equipped with multiple antennas, whereas the UAV has a single antenna. Then, we obtain the output signal-to-noise ratio (SNR of the dual-hop relay network. Based on the criterion of maximizing the output SNR, we develop an optimal design to obtain the solution of the optimal BF weight vector and the UAV heading angle. Next, we derive the closed-form outage probability (OP expression to investigate the performance of the dual-hop relay network conveniently. Finally, computer simulations show that the proposed approach can obtain nearly optimal flying path and OP performance, indicating the effectiveness of the proposed algorithm. Furthermore, we find that increasing the antenna number at the BS or the maximal heading angle can significantly improve the performance of the considered relay network.

  19. The Physical Layer Security Experiments of Cooperative Communication System with Different Relay Behaviors.

    Science.gov (United States)

    Su, Yishan; Han, Guangyao; Fu, Xiaomei; Xu, Naishen; Jin, Zhigang

    2017-04-06

    Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF) cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1) to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2) the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3) the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission.

  20. Effects of a voltage compensation type active superconducting fault current limiter on distance relay protection

    Science.gov (United States)

    Chen, L.; Tang, Y. J.; Shi, J.; Ren, L.; Song, M.; Cheng, S. J.; Hu, Y.; Chen, X. S.

    2010-11-01

    On the basis of a voltage compensation type active superconducting fault current limiter (SFCL) proposed in previous work, the effects of this type SFCL on distance relay protection are studied in this paper. Under the condition that the active SFCL is placed behind the relay element, its current-limiting impedance will be added into the measured impedance between the relay and the fault points. As a result, in order to prevent the refused operation of the relay, the measured impedance should be revised. According to the three different operation modes of the active SFCL, we present the corresponding three modified formulas. Furthermore, using MATLAB, the model of the dual-source power system with the active SFCL is built, and the impacts of the active SFCL on the distance relay protection are studied in detail under the different current-limiting modes and fault distances. The simulation results show that: without using the modified formulas, the introduction of the active SFCL will reduce the protection distance of the relay, and in the case that the modified formulas are adopted, the three modes of the active SFCL will not affect the measured impedance of the relay, and further the validities of the proposed modified formulas can be testified.

  1. Wireless Relay Selection in Pocket Switched Networks Based on Spatial Regularity of Human Mobility.

    Science.gov (United States)

    Huang, Jianhui; Cheng, Xiuzhen; Bi, Jingping; Chen, Biao

    2016-01-18

    Pocket switched networks (PSNs) take advantage of human mobility to deliver data. Investigations on real-world trace data indicate that human mobility shows an obvious spatial regularity: a human being usually visits a few places at high frequencies. These most frequently visited places form the home of a node, which is exploited in this paper to design two HomE based Relay selectiOn (HERO) algorithms. Both algorithms input single data copy into the network at any time. In the basic HERO, only the first node encountered by the source and whose home overlaps a destination's home is selected as a relay while the enhanced HERO keeps finding more optimal relay that visits the destination's home with higher probability. The two proposed algorithms only require the relays to exchange the information of their home and/or the visiting frequencies to their home when two nodes meet. As a result, the information update is reduced and there is no global status information that needs to be maintained. This causes light loads on relays because of the low communication cost and storage requirements. Additionally, only simple operations are needed in the two proposed algorithms, resulting in little computation overhead at relays. At last, a theoretical analysis is performed on some key metrics and then the real-world based simulations indicate that the two HERO algorithms are efficient and effective through employing only one or a few relays.

  2. Outage Probability Analysis in Power-Beacon Assisted Energy Harvesting Cognitive Relay Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ngoc Phuc Le

    2017-01-01

    Full Text Available We study the performance of the secondary relay system in a power-beacon (PB assisted energy harvesting cognitive relay wireless network. In our system model, a secondary source node and a relay node first harvest energy from distributed PBs. Then, the source node transmits its data to the destination node with the help of the relay node. Also, fading coefficients of the links from the PBs to the source node and relay node are assumed independent but not necessarily identically distributed (i.n.i.d Nakagami-m random variables. We derive exact expressions for the power outage probability and the channel outage probability. Based on that, we analyze the total outage probability of the secondary relay system. Asymptotic analysis is also performed, which provides insights into the system behavior. Moreover, we evaluate impacts of the primary network on the performance of the secondary network with respect to the tolerant interference threshold at the primary receiver as well as the interference introduced by the primary transmitter at the secondary source and relay nodes. Simulation results are provided to validate the analysis.

  3. Development of Support System for Setting and Coordination between Protection Relays

    Science.gov (United States)

    Kameda, Hideyuki; Uemura, Satoshi; Uchikawa, Yuuki; Nakajima, Takayuki

    The opportunity for distributed generators to be connected to the power system has been increasing since the introduction of electricity deregulation. Moreover, a power system which has a new concept such as a micro-grid or a smart-grid is going to appear. The increase in the uncertainty of power flow and the power system operation under an irregular system configuration is supposed in such new power systems. And the sensitivity of a protection relay may decrease or a protection relay may miscoordinate with other protection relays. Under the above conditions, to prevent the fault expansion is required of the electric power utilities. From the background, the development of a program that can check the relay setting and the coordination between protection relay systems is desired. The development of “Support System for Setting and Coordination between protection relays” called SSSC was initiated in 2006, and it will be completed in 2011. SSSC has the following features ·It enables us to check whether the protection relay is set as operate correctly against all of assumed system faults. ·It enables us to check automatically whether the coordination between the protection relays is proper as prevent the fault extension even if an unexpected condition occurs. ·It enables us to analyze the response of the protection relays in the power system where some apparatus with nonlinear characteristic is installed. This paper describes the prototype of the SSSC based on the dynamic analysis like Y-method. Furthermore, in this paper, the checking method of coordination between protection relays for short circuit fault, and the verification results of the prototype in the 6.6kV model distribution system are described.

  4. 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.

  5. Performance Analysis of Virtual MIMO Relaying Schemes Based on Detect–Split–Forward

    KAUST Repository

    Al-Basit, Suhaib M.

    2014-10-29

    © 2014, Springer Science+Business Media New York. Virtual multi-input multi-output (vMIMO) schemes in wireless communication systems improve coverage, throughput, capacity, and quality of service. In this paper, we propose three uplink vMIMO relaying schemes based on detect–split–forward (DSF). In addition, we investigate the effect of several physical parameters such as distance, modulation type and number of relays. Furthermore, an adaptive vMIMO DSF scheme based on VBLAST and STBC is proposed. In order to do that, we provide analytical tools to evaluate the performance of the propose vMIMO relaying scheme.

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

    KAUST Repository

    Yang, Liang

    2012-08-01

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

  7. Incorporating Multiple Energy Relay Dyes in Liquid Dye-Sensitized Solar Cells

    KAUST Repository

    Yum, Jun-Ho

    2011-01-05

    Panchromatic response is essential to increase the light-harvesting efficiency in solar conversion systems. Herein we show increased light harvesting from using multiple energy relay dyes inside dye-sensitized solar cells. Additional photoresponse from 400-590 nm matching the optical window of the zinc phthalocyanine sensitizer was observed due to Förster resonance energy transfer (FRET) from the two energy relay dyes to the sensitizing dye. The complementary absorption spectra of the energy relay dyes and high excitation transfer efficiencies result in a 35% increase in photovoltaic performance. © 2011 Wiley-VCH Verlag GmbH& Co. KGaA.

  8. Simultaneous Wireless Power Transfer and Secure Multicasting in Cooperative Decode-and-Forward Relay Networks.

    Science.gov (United States)

    Lee, Jong-Ho; Sohn, Illsoo; Kim, Yong-Hwa

    2017-05-16

    In this paper, we investigate simultaneous wireless power transfer and secure multicasting via cooperative decode-and-forward (DF) relays in the presence of multiple energy receivers and eavesdroppers. Two scenarios are considered under a total power budget: maximizing the minimum harvested energy among the energy receivers under a multicast secrecy rate constraint; and maximizing the multicast secrecy rate under a minimum harvested energy constraint. For both scenarios, we solve the transmit power allocation and relay beamformer design problems by using semidefinite relaxation and bisection technique. We present numerical results to analyze the energy harvesting and secure multicasting performances in cooperative DF relay networks.

  9. Computer Aided Design Of Relay Ladder Logic Via State Transition Diagram

    Science.gov (United States)

    Devanathan, R.; Kuan, Foo Y.; Jun, Chang C.; Aun, Choo S.

    1987-10-01

    Programmable logic controllers (PLCs) are commonly programmed using relay ladder logic. There are many disadvantages to this approach. The state transition diagram affords a systematic means of providing precise and unambiguous specification while at the same time yielding a good system overview for ease of troubleshooting and maintenance. Computer aided logic design techniques help to automate the process of relay logic design for the state transition diagram. A software package which runs on an IBM PC/compatible machine has been developed to automatically transform the state diagram specification into relay ladder logic and the associated (PLC dependent) source code.

  10. Performance Analysis of Relays in LTE for a Realistic Suburban Deployment Scenario

    DEFF Research Database (Denmark)

    Coletti, Claudio; Mogensen, Preben; Irmer, Ralf

    2011-01-01

    Relays are likely to play an important role in the deployment of Beyond 3G networks, such as LTE-Advanced, thanks to the possibility of effectively extending Macro network coverage and fulfilling the expected high data-rate requirements. Up until now, the relay technology potential and its cost......-effectiveness have been widely investigated in the literature, considering mainly statistical deployment scenarios, like regular networks with uniform traffic distribution. This paper is envisaged to illustrate the performances of different relay technologies (In-Band/Out-band) in a realistic suburban network...

  11. Functional-Decode-Forward for the General Discrete Memoryless Two-Way Relay Channel

    CERN Document Server

    Ong, Lawrence; Johnson, Sarah J; 10.1109/ICCS.2010.5686490

    2011-01-01

    We consider the general discrete memoryless two-way relay channel, where two users exchange messages via a relay, and propose two functional-decode-forward coding strategies for this channel. Functional-decode-forward involves the relay decoding a function of the users' messages rather than the individual messages themselves. This function is then broadcast back to the users, which can be used in conjunction with the user's own message to decode the other user's message. Via a numerical example, we show that functional-decode-forward with linear codes is capable of achieving strictly larger sum rates than those achievable by other strategies.

  12. 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 Decision...... in the presence of active neighbours compared to multicasting directly from the source. We further show that in scenarios which the links between relay and destinations are not better than the links between source and destinations, a relay can still provide up to 1.7x gain....

  13. Secure and Usable Out-Of-Band Channels for Ad Hoc Mobile Device Interactions

    OpenAIRE

    Kainda, Ronald; Flechais, Ivan; Roscoe, A.W.

    2010-01-01

    International audience; Protocols for bootstrapping security in ad hoc mobile device interactions rely on users' ability to perform specific tasks such as transferring or comparing fingerprints of information between devices. The size of fingerprints depends on the level of technical security required by a given application but, at the same time, is limited by users' inability to deal with large amounts of data with high levels of accuracy. Large fingerprints provide high technical security b...

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

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-12-01

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

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

    KAUST Repository

    Tourki, Kamel

    2010-10-01

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

  16. Joint Linear Filter Design in Multiuser Cooperative Nonregenerative MIMO Relay Systems

    Directory of Open Access Journals (Sweden)

    Li Gen

    2009-01-01

    Full Text Available This paper addresses the filter design issues for multiuser cooperative nonregenerative MIMO relay systems in both downlink and uplink scenarios. Based on the formulated signal model, the filter matrix optimization is first performed for direct path and relay path respectively, aiming to minimize the mean squared error (MSE. To be more specific, for the relay path, we derive the local optimal filter scheme at the base station and the relay station jointly in the downlink scenario along with a more practical suboptimal scheme, and then a closed-form joint local optimal solution in the uplink scenario is exploited. Furthermore, the optimal filter for the direct path is also presented by using the exiting results of conventional MIMO link. After that, several schemes are proposed for cooperative scenario to combine the signals from both paths. Numerical results show that the proposed schemes can reduce the bit error rate (BER significantly.

  17. Efficient power allocation for fixed-gain amplify-and-forward relaying in rayleigh fading

    KAUST Repository

    Zafar, Ammar

    2013-06-01

    In this paper, we study power allocation strategies for a fixed-gain amplify-and-forward relay network employing multiple relays. We consider two optimization problems for the relay network: 1) optimal power allocation to maximize the end-to-end signal-to-noise ratio (SNR) and 2) minimizing the total consumed power while maintaining the end-to-end SNR over a threshold value. We assume that the relays have knowledge of only the channel statistics of all the links. We show that the SNR maximization problem is concave and the power minimization problem is convex. Hence, we solve the problems through convex programming. Numerical results show the benefit of allocating power optimally rather than uniformly. © 2013 IEEE.

  18. Emergency Load Shedding Strategy Based on Sensitivity Analysis of Relay Operation Margin against Cascading Events

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Sun, Haishun Sun

    2012-01-01

    In order to prevent long term voltage instability and induced cascading events, a load shedding strategy based on the sensitivity of relay operation margin to load powers is discussed and proposed in this paper. The operation margin of critical impedance backup relay is defined to identify...... the runtime emergent states of related system component. Based on sensitivity analysis between the relay operation margin and power system state variables, an optimal load shedding strategy is applied to adjust the emergent states timely before the unwanted relay operation. Load dynamics is also taken...... into account to compensate load shedding amount calculation. And the multi-agent technology is applied for the whole strategy implementation. A test system is built in real time digital simulator (RTDS) and has demonstrated the effectiveness of the proposed strategy....

  19. Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment

    KAUST Repository

    Sboui, Lokman

    2015-04-21

    We study the impact of multiple relays on the primary user (PU) and secondary user (SU) rates of underlay MIMO cognitive radio. Both users exploit amplify-and-forward relays to communicate with the destination. A space alignment technique and a special linear precoding and decoding scheme are applied to allow the SU to use the resulting free eigenmodes. In addition, the SU can communicate over the used eigenmodes under the condition of respecting an interference constraint tolerated by the PU. At the destination, a successive interference cancellation (SIC) is performed to estimate the secondary signal. We present the explicit expressions of the optimal PU and SU powers that maximize their achievable rates. In the numerical results, we show that our scheme provides cognitive rate gain even in absence of tolerated interference. In addition, we show that increasing the number of relays enhances the PU and SU rates at low power regime and/or when the relays power is sufficiently high.

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

    National Research Council Canada - National Science Library

    Qiao Liu; Guang Gong; Yong Wang; Hui Li

    2017-01-01

    .... 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...

  1. Source-Channel Coding Theorems for the Multiple-Access Relay Channe

    CERN Document Server

    Murin, Yonathan; Gündüz, Deniz

    2011-01-01

    Reliable transmission of arbitrarily correlated sources over multiple-access relay channels (MARCs) and multiple-access broadcast relay channels (MABRCs) is considered. In MARCs only the destination is interested in a reconstruction of the sources, while in MABRCs both the relay and the destination want to reconstruct the sources. In addition to arbitrary correlation among the source signals at the users, both the relay and the destination are assumed to have side information correlated with the source signals. Sufficient conditions for reliable communication based on operational separation, as well as necessary conditions on the achievable source-channel rates are characterized. Since operational separation is generally not optimal for MARCs and MABRCs, sufficient conditions for reliable communication using joint source-channel coding schemes based on a combination of the correlation preserving mapping technique with binning are also derived. For correlated sources transmitted over fading Gaussian MARCs and ...

  2. Towards a Low-Complexity Dynamic Decode-and-Forward Relay Protocol

    CERN Document Server

    Hucher, Charlotte

    2010-01-01

    The dynamic decode-and-forward (DDF) relaying protocol is a relatively new cooperative scheme which has been shown to achieve promising theoretical results in terms of diversity-multiplexing gain tradeoff and error rates. The case of a single relay has been extensively studied in the literature and several techniques to approach the optimum performance have been proposed. Until recently, however, a practical implementation for the case of several relays had been considered to be much more challenging. A rotation-based DDF technique, suitable for any number of relays, has been recently proposed which promises to overcome important implementation hurdles. This article provides an overview of the DDF protocol, describes different implementation techniques and compares their performance.

  3. The Role of Remotely Sensed and Relayed Data in the Delaware River Basin

    Science.gov (United States)

    Paulson, R. W.

    1971-01-01

    The planned integration of the existing water quality monitoring and data processing systems in the Delaware River Basin with a data relay experiment proposed for the ERTS-1 is discussed. The experiment is designed to use ERTS-1 as a data relay link for a maximum of 20 hydrologic stations in the basin, including stream gaging, reservoir level, ground water level, and water quality monitoring stations. This experiment has the potential for reducing the time lag between data collection and dissemination to less than 12 hours. The experiment will also provide impetus to develop an operational system of real time data processing and dissemination to handle the large quantity of data that will be obtained from the stations in the basin. The results of this experiment will demonstrate the relative merits of satellite relay of data versus conventional means of data telemetry and will provide a basis for the development of operational satellite relay of hydrologic data.

  4. Performance of Amplify-and-Forward Multihop Transmission over Relay Clusters with Different Routing Strategies

    CERN Document Server

    Yilmaz, Ferkan; Alouini, Mohamed-Slim

    2012-01-01

    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 symbol to noise ratio (SNR). The ASEP performance of a better protocol proposed in [1] 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-n-hop selection protocol, the dual path protocol, the forward- backward last-n-hop selection protocol, and the forwa...

  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. Ergodic capacity analysis for MIMO two-hop relay system based on decode-and-forward

    Directory of Open Access Journals (Sweden)

    CHEN Birong

    2012-08-01

    Full Text Available This paper presents an ergodic capacity analysis of MIMO two-hop relaying systems based on the relay protocol of decode-and-forward.Firstly the expression for the probability density function of an unordered eigenvalue of the system is derived.Then a closed-form solution of the ergodic capacity of the entire system is given through the probability density function based on a new random matrix theory.This closed-form solution can be used not only to the SISO system but also to the source,relay and destination of arbitrary numbers of antennas.The result of simulations shows that the theory analysis matches the simulations and the ergodic capacity is improved in comparison with the simple relay protocol of amplify-and-forward.

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

    KAUST Repository

    Tourki, Kamel

    2011-06-01

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

  8. A Novel Design of Radio Frequency Energy Relays on Power Transmission Lines

    Directory of Open Access Journals (Sweden)

    Jin Tong

    2016-06-01

    Full Text Available In this paper, we investigate the energy problem of monitoring sensors on high-voltage power transmission lines and propose a wireless charging scheme for a Radio Frequency IDentification (RFID sensor tag to solve a commercial efficiency problem: the maintenance-caused power outage. Considering the environmental influences on power transmission lines, a self-powered wireless energy relay is designed to meet the energy requirement of the passive RFID sensor tag. The relay can obtain the electric field energy from the transmission lines and wirelessly power the RFID sensor tags around for longer operating distance. A prototype of the energy relay is built and tested on a 110 kv line. The measurement results show that the energy relay can provide stable energy even with the influences of wind, noise and power outage. To our knowledge, it is the first work to power the RFID sensor tags on power transmission lines.

  9. 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 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......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...

  10. 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.

  11. Novel half-coherent receivers for amplify-and-forward relaying

    KAUST Repository

    Khan, Fahd Ahmed

    2012-06-01

    Consider a system in which the signal is transmitted from the source to the destination via an amplify-and-forward relay. For such a system, we derive in this paper, novel receivers that have complete knowledge of either the source-relay link or the relay-destination link. These receivers are termed as, \\'half-coherent receivers\\' as they have channel-state-information (CSI) of only one of two links. These receivers can be very useful in a system in which only the relay can afford high complexity by having a channel estimation module and the destination is unable to support channel estimation or a system in which only the destination can afford higher complexity and includes the channel estimation module. The analytical bit-error-rate (BER) performances of the proposed receivers are derived for Rician fading. Numerical results show considerable performance gains of the new receivers, especially at low signal-to-noise ratio. © 2012 IEEE.

  12. Design of a new Hall overcurrent protection relay with instantaneous characteristics

    National Research Council Canada - National Science Library

    Tsai, Yuan-Pin; Chen, Kun-Long; Chen, Yan-Ru; Chen, Nanming

    2015-01-01

    Traditional current transformers (CTs) detect fault currents and transfer signals to overcurrent protection relays for indicative and protective purposes as a part of the protection coordination system in a power network...

  13. Research on Motor Relay Protection of High-Voltage Variable Frequency Motor Drive System

    National Research Council Canada - National Science Library

    Huo, Lijie; Li, Bing; Hu, Xuan; Liu, Chunsong

    2014-01-01

    .... Firstly, this paper introduces the traditional principle and setting methods of them, and points out that the traditional relay protection device is no longer applicable under the situation of high...

  14. Tests of microprocessor-based relay protection devices: Problems and solutions

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2009-01-01

    Full Text Available Usually, the operational condition of relay protection devices is checked with specific settings used for the relay operation in a certain network point. In the author's opinion in order to verify the proper operation of complex multifunctional microprocessor-based protection devices (MPD at their inspection, start-up after repairs or during periodic tests there is no need to use the actual settings at which the relay is to be operated in a certain network's point. It should be tested for proper operation at several of its most critical preset characteristic points as well as in several preset characteristics constituting its most complicated (combined operation modes, including the dynamic operation modes with preset transition processes specific for standard power networks (not necessarily for a specific point. The proposed set of actions for the unification of software platforms of the modern, microprocessor-based relay protection test systems will enable examination of modern MPD in an absolutely new way. .

  15. Variation of UPFC Controllable Parameters during Power Swing and their Impacts on Distance Relay

    DEFF Research Database (Denmark)

    Khodaparast, Jalal; Khederzadeh, Mojtaba; Silva, Filipe Miguel Faria da

    2017-01-01

    Unified power flow controller (UPFC) has impact on the performance of distance relay during power swing. Generally, power system's parameters oscillate during power swing and since UPFC operation depends on some of these parameters (bus voltage, active and reactive power), the UPFC injects...... oscillated series voltage and draws oscillated shunt current. These oscillating series voltage and shunt current influence distance relays, as the impedance seen by a distance relay during power swing changes in UPFC-compensated lines. This study shows how and why series voltage and shunt current change...... during power swing. Moreover, the admittance swing characteristic is proposed in this study and effects of series and shunt branches of UPFC on the admittance seen by a distance relay during power swing have been examined....

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

    Science.gov (United States)

    Ilik, Semih C.; Arsoy, Aysen B.

    2017-07-01

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

  17. Optimal combined overcurrent and distance relays co-ordination using a new genetic algorithm method

    Energy Technology Data Exchange (ETDEWEB)

    Kamangar, S.S.H.; Abyaneh, H.A.; Chabanloo, R.M. [Amirkabir Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering; Razavi, F. [Tafresh Univ. (Iran, Islamic Republic of). Dept. of Electrical Engineering

    2010-04-15

    This paper introduced a new method to optimize the coordination of overcurrent (OC) relays using genetic algorithm (GA). GA is an intelligent optimization technique that can adjust the setting of relays without being based on an initial guess or trapped in the local minimum values, which is the disadvantage of linear programming techniques, such as simplex, 2-phase simplex, and dual simplex techniques. The objective function (OF) of GA is modified by adding a new term to OF to fulfill the coordination of both OC and distance relays. Two power network systems were analyzed using the new computer program, and the results that were obtained show that the method is both efficient and accurate. Transmission and subtransmission protection systems commonly use OC and distance relays. 12 refs., 6 tabs., 5 figs.

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

    Directory of Open Access Journals (Sweden)

    Lazhar Bougouffa

    2016-03-01

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

  19. The Finite Field Multi-Way Relay Channel with Correlated Sources: The Three-User Case

    CERN Document Server

    Ong, Lawrence; Lechner, Gottfried; Johnson, Sarah J; Kellett, Christopher M

    2011-01-01

    The three-user finite field multi-way relay channel with correlated sources is considered. The three users generate possibly correlated messages, and each user is to transmit its message to the two other users reliably in the Shannon sense. As there is no direct link among the users, communication is carried out via a relay, and the link from the users to the relay and those from the relay to the users are finite field adder channels with additive noise of arbitrary distribution. The problem is to determine the set of all possible achievable rates, defined as channel uses per source symbol for reliable communication. For two classes of source/channel combinations, the solution is obtained using Slepian-Wolf source coding combined with functional-decode-forward channel coding.

  20. 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.

  1. 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.

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

    DEFF Research Database (Denmark)

    Kaneko, Megumi; Hayashi, Kazunori; Popovski, Petar

    2013-01-01

    Many works have tackled on the problem of throughput and fairness optimization in cellular cooperative relaying systems. Considering firstly a two-user relay broadcast channel, we design a scheme based on superposition coding (SC) which maximizes the achievable sum-rate under a proportional...... outperform conventional schedulers based on orthogonal user allocation, both in terms of throughput and proportional fairness. These results indicate promising new directions for the design of future radio resource allocation and scheduling algorithms....

  3. Simulation of Low Nickel Content Alloys For Industrial Ground Fault Circuit-Breaker Relays

    OpenAIRE

    Messal, Oualid; Sixdenier, Fabien; Morel, Laurent; Burais, Noël; Waeckerle, Thierry

    2014-01-01

    International audience; The aim of this paper is to simulate the performances of a ground fault circuit-breaker (GFCB) relay with new low nickel content alloys. Indeed, in the construction industry, the materials become more expensive as their nickel content increases. Moreover, the demand for nickel is particularly sensitive to the economic conjuncture. Therefore, an original electromagnetic relay model has been developed and validated in different working conditions (current amplitude, freq...

  4. 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.

  5. Detection of vulnerable relays and sensitive controllers under cascading events based on performance indices

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Hu, Yanting

    2014-01-01

    ) based detection strategy is proposed to identify the vulnerable relays and sensitive controllers under the overloading situation during cascading events. Based on the impedance margin sensitivity, diverse performance indices are proposed to help improving this detection. A study case of voltage...... instability induced cascaded blackout built in real time digital simulator (RTDS) will be used to demonstrate the proposed strategy. The simulation results indicate this strategy can effectively detect the vulnerable relays and sensitive controllers under overloading situations....

  6. A Novel Design of Radio Frequency Energy Relays on Power Transmission Lines

    OpenAIRE

    Jin Tong; Yigang He; Bing Li; Fangming Deng; Tao Wang

    2016-01-01

    In this paper, we investigate the energy problem of monitoring sensors on high-voltage power transmission lines and propose a wireless charging scheme for a Radio Frequency IDentification (RFID) sensor tag to solve a commercial efficiency problem: the maintenance-caused power outage. Considering the environmental influences on power transmission lines, a self-powered wireless energy relay is designed to meet the energy requirement of the passive RFID sensor tag. The relay can obtain the elect...

  7. Peer Effects in Team Sports: Empirical Evidence from NCAA Relay Teams

    OpenAIRE

    Craig A. Depken, II; Lisa E. Haglund

    2007-01-01

    This paper investigates whether disparity in team member quality impacts team production using NCAA 4x400m relay teams. The net peer effects are estimated to have both an absolute and relative negative effect on the team performance. Because NCAA relay teams are comprised of unpaid amateurs, we utilize a direct measure of team-member quality rather than indirect measures such as wages. The evidence suggests that a greater disparity in team member quality reduces team performance, that is, it ...

  8. The 44th success of the CERN Relay Race

    CERN Multimedia

    Anaïs Schaeffer

    2014-01-01

    On Thursday 5 June, 590 people (8 Nordic walkers and 97 teams of 6 runners each) took part in the 44th CERN Relay Race.   The teams were divided into 8 different categories: mixed, mixed open, women, women open, men, men open, men veterans and Nordic Walk. The participants covered 3,900 metres around the Meyrin site, with the race's winners covering this distance in only 11 minutes and 4 seconds! (See all the results here.) All the participants received a souvenir prize and the winners of each category took home a trophy. Additional prizes were given to the winners of the 1000 m challenge and Challenge Entreprise, and to the best CERN Users and Associates team, Department team and fancy dress team. Everybody had a very good time, thanks to the excellent weather and the dynamic and friendly atmosphere created by the CERN Clubs! The Running Club would like to thank the Staff Association, the CERN Management and services, the event’s sponsors and, especially, all the volunteers...

  9. Distributed Cooperative Transmission with Unreliable and Untrustworthy Relay Channels

    Directory of Open Access Journals (Sweden)

    Sun YanLindsay

    2009-01-01

    Full Text Available Cooperative transmission is an emerging wireless communication technique that improves wireless channel capacity through multiuser cooperation in the physical layer. It is expected to have a profound impact on network performance and design. However, cooperative transmission can be vulnerable to selfish behaviors and malicious attacks, especially in its current design. In this paper, we investigate two fundamental questions Does cooperative transmission provide new opportunities to malicious parties to undermine the network performance? Are there new ways to defend wireless networks through physical layer cooperation? Particularly, we study the security vulnerabilities of the traditional cooperative transmission schemes and show the performance degradation resulting from the misbehaviors of relay nodes. Then, we design a trust-assisted cooperative scheme that can detect attacks and has self-healing capability. The proposed scheme performs much better than the traditional schemes when there are malicious/selfish nodes or severe channel estimation errors. Finally, we investigate the advantage of cooperative transmission in terms of defending against jamming attacks. A reduction in link outage probability is achieved.

  10. CERN Relay Race: The Shabbys again, but only just!

    CERN Multimedia

    2006-01-01

    Gregor Grawer of the Shabbys bringing his team to a narrow victory over ALICE - Out of Control. The sun was shining as the start was given for this year's CERN Relay Race with a record 65 teams at the starting line. 'ALICE - Out of Control' held an impressive lead from the start but were eventually overtaken in the last 300 metres by the Shabbys. In doing so, they claimed their sixth consecutive victory with a time of 10 min 39,9 sec, the fastest they have ever run. This year for the first time a new trophy was awarded for the fastest woman at the 1000 metres line which was won by Helenka Przysiezniak of the Running Athenas, while the men's trophy went to Marc Magrans de Abril of ALICE - Out of Control in 2 min 45 sec. The good weather contributed to the festive atmosphere as runners and spectators relaxed on the lawn of Restaurant No. 1 accompanied by music by the CERN Jazz Club's excellent 'Pink Symbolic Stompers'. The CERN Audiovisual Service and the 'Open Your Eyes' filmmaking club were on hand to recor...

  11. 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.

  12. The impact of SFCL and SMES integration on the distance relay

    Science.gov (United States)

    Yang, Jun; Zhang, Liling; Wang, Xinpu; Chen, Lei; Chen, Yanxia

    2016-11-01

    The superconducting fault current limiter (SFCL) is an ideal short-circuit fault current limiting device that can limit the fault current without any delay and control the voltage drop of the non-fault line. The superconducting magnetic energy storage (SMES) device can exchange the active and reactive power independently, so it is applied broadly to improve power system stability. With SFCL, the low voltage ride-through capability of SMES can be enhanced as well as its MW and MJ capacities. The distance relay is a key electrical apparatus that will trip circuit breakers to protect electrical devices from short circuit faults. Due to the application of SFCL and SMES integration, the voltage and current in power grid will change accordingly, and the operation characteristic of distance relay may be affected. In this paper, the impact of a bridge-type SFCL and SMES integration on the circle distance relay is studied. And simulation results show that the integration of SFCL and SMES does influence the measured impedance of distance relay, which can lead to mal-operation of the circle distance relay. Furthermore, an improved distance relay is proposed and verified.

  13. Self-oscillations in dynamic systems a new methodology via two-relay controllers

    CERN Document Server

    Aguilar, Luis T; Fridman, Leonid; Iriarte, Rafael

    2015-01-01

    This monograph presents a simple and efficient two-relay control algorithm for generation of self-excited oscillations of a desired amplitude and frequency in dynamic systems. Developed by the authors, the two-relay controller consists of two relays switched by the feedback received from a linear or nonlinear system, and represents a new approach to the self-generation of periodic motions in underactuated mechanical systems. The first part of the book explains the design procedures for two-relay control using three different methodologies – the describing-function method, Poincaré maps, and the locus-of-a perturbed-relay-system method – and concludes with stability analysis of designed periodic oscillations. Two methods to ensure the robustness of two-relay control algorithms are explored in the second part, one based on the combination of the high-order sliding mode controller and backstepping, and the other on higher-order sliding-modes-based reconstruction of uncertainties and their compensation where...

  14. Mars Relay Operations Service (MaROS): A Present Service Preparing for the Future

    Science.gov (United States)

    Gladden, Roy E.

    2014-01-01

    The Mars Relay Operations Service (MaROS) has been deployed by NASA's Mars Program Office and the Multimission Ground Systems and Services (MGSS) Project into mission operations to aid in the coordination of relay activities at Mars. This live system presents standardized interfaces and a centralized infrastructure to current and future participants in the Mars Relay Network for the purpose of reliably and securely exchanging and storing all relay-related planning and operations data. The initial development of this system leveraged over eight years of experience performing relay operations between the various spacecraft at Mars. Now, four years after its initial deployment, MaROS continues to undergo further refinement to better meet the needs of the Mars Relay Network. The most substantial, recent update was focused on providing capabilities needed by the Mars Science Laboratory project, which landed on Mars in August of 2012. This paper will describe the nature of that update and describe additional features being added to the system to better serve the needs of current and future Mars missions.

  15. Relay cropping as a sustainable approach: problems and opportunities for sustainable crop production.

    Science.gov (United States)

    Tanveer, Mohsin; Anjum, Shakeel Ahmad; Hussain, Saddam; Cerdà, Artemi; Ashraf, Umair

    2017-03-01

    Climate change, soil degradation, and depletion of natural resources are becoming the most prominent challenges for crop productivity and environmental sustainability in modern agriculture. In the scenario of conventional farming system, limited chances are available to cope with these issues. Relay cropping is a method of multiple cropping where one crop is seeded into standing second crop well before harvesting of second crop. Relay cropping may solve a number of conflicts such as inefficient use of available resources, controversies in sowing time, fertilizer application, and soil degradation. Relay cropping is a complex suite of different resource-efficient technologies, which possesses the capability to improve soil quality, to increase net return, to increase land equivalent ratio, and to control the weeds and pest infestation. The current review emphasized relay cropping as a tool for crop diversification and environmental sustainability with special focus on soil. Briefly, benefits, constraints, and opportunities of relay cropping keeping the goals of higher crop productivity and sustainability have also been discussed in this review. The research and knowledge gap in relay cropping was also highlighted in order to guide the further studies in future.

  16. Throughput Characterization for Cooperative Wireless Information Transmission with RF Energy Harvesting-Based Relay

    Directory of Open Access Journals (Sweden)

    Yuanyuan Yao

    2016-01-01

    Full Text Available The simultaneous wireless information and power transfer (SWIPT in a cooperative relaying system is investigated, where the relay node is self-sustained by harvesting radiofrequency (RF energy from the source node. In this paper, we propose a time switching and power splitting (TSPS protocol for the cooperative system with a mobile destination node. In the first part of the transmission slot, a portion of the received signal power is used for energy transfer, and the remaining power is used for information transmission from the source to the relay. For the remaining time of the transmission slot, information is transmitted from the relay to a mobile destination node. To coordinate the wireless information and power transfer, two transmission modes are investigated, namely, relay-assisted transmission mode and nonrelay mode, respectively. Under these two modes, the outage probability and the network throughput are characterized. By joint optimization of the power splitting and the time switching ratios, we further compare the network throughput under the two transmission modes with different parameters. Results indicate that the relay-assisted transmission mode significantly improves the throughput of the wireless network.

  17. 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.

  18. Physical Layer Authentication Enhancement Using Maximum SNR Ratio Based Cooperative AF Relaying

    Directory of Open Access Journals (Sweden)

    Jiazi Liu

    2017-01-01

    Full Text Available Physical layer authentication techniques developed in conventional macrocell wireless networks face challenges when applied in the future fifth-generation (5G wireless communications, due to the deployment of dense small cells in a hierarchical network architecture. In this paper, we propose a novel physical layer authentication scheme by exploiting the advantages of amplify-and-forward (AF cooperative relaying, which can increase the coverage and convergence of the heterogeneous networks. The essence of the proposed scheme is to select the best relay among multiple AF relays for cooperation between legitimate transmitter and intended receiver in the presence of a spoofer. To achieve this goal, two best relay selection schemes are developed by maximizing the signal-to-noise ratio (SNR of the legitimate link to the spoofing link at the destination and relays, respectively. In the sequel, we derive closed-form expressions for the outage probabilities of the effective SNR ratios at the destination. With the help of the best relay, a new test statistic is developed for making an authentication decision, based on normalized channel difference between adjacent end-to-end channel estimates at the destination. The performance of the proposed authentication scheme is compared with that in a direct transmission in terms of outage and spoofing detection.

  19. Development and Testing of a Two-UAV Communication Relay System

    Directory of Open Access Journals (Sweden)

    Boyang Li

    2016-10-01

    Full Text Available In the development of beyond-line-of-sight (BLOS Unmanned Aerial Vehicle (UAV systems, communication between the UAVs and the ground control station (GCS is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by obstacles. The use of a communication relay system provides a practical way to solve these problems, improving the performance of UAV communication in BLOS and cross-obstacle operations. In this study, a communication relay system, in which a quadrotor was used to relay radio communication for another quadrotor was developed and tested. First, the UAVs used as the airborne platform were constructed, and the hardware for the communication relay system was selected and built up. Second, a set of software programs and protocol for autonomous mission control, communication relay control, and ground control were developed. Finally, the system was fully integrated into the airborne platform and tested both indoor and in-flight. The Received Signal Strength Indication (RSSI and noise value in two typical application scenarios were recorded. The test results demonstrated the ability of this system to extend the communication range and build communication over obstacles. This system also shows the feasibility to coordinate multiple UAVs’ communication with the same relay structure.

  20. 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.

  1. Secure Communication for Two-Way Relay Networks with Imperfect CSI

    Directory of Open Access Journals (Sweden)

    Cong Sun

    2017-09-01

    Full Text Available This paper considers a two-way relay network, where two legitimate users exchange messages through several cooperative relays in the presence of an eavesdropper, and the Channel State Information (CSI of the eavesdropper is imperfectly known. The Amplify-and-Forward (AF relay protocol is used. We design the relay beamforming weights to minimize the total relay transmit power, while requiring the Signal-to-Noise-Ratio (SNRs of the legitimate users to be higher than the given thresholds and the achievable rate of the eavesdropper to be upper-bounded. Due to the imperfect CSI, a robust optimization problem is summarized. A novel iterative algorithm is proposed, where the line search technique is applied, and the feasibility is preserved during iterations. In each iteration, two Quadratically-Constrained Quadratic Programming (QCQP subproblems and a one-dimensional subproblem are optimally solved. The optimality property of the robust optimization problem is analyzed. Simulation results show that the proposed algorithm performs very close to the non-robust model with perfect CSI, in terms of the obtained relay transmit power; it~achieves higher secrecy rate compared to the existing work. Numerically, the proposed algorithm converges very quickly, and more than 85% of the problems are solved optimally.

  2. Orthogonal DF Cooperative Relay Networks with Multiple-SNR Thresholds and Multiple Hard-Decision Detections

    Directory of Open Access Journals (Sweden)

    Dian-Wu Yue

    2010-01-01

    Full Text Available This paper investigates a wireless cooperative relay network with multiple relays communicating with the destination over orthogonal channels. Proposed is a cooperative transmission scheme that employs two signal-to-noise ratio (SNR thresholds and multiple hard-decision detections (HDD at the destination. One SNR threshold is used to select transmitting relays, and the other threshold is used at the destination for detection. Then the destination simply combines all the hard-decision results and makes the final binary decision based on majority voting. Focusing on the decode-and-forward (DF relaying protocol, the average bit error probability is derived and diversity analysis is carried out. It is shown that the full diversity order can be achieved by setting appropriate thresholds even when the destination does not know the exact or average SNRs of the source-relay links. The performance analysis is further extended to multi-hop cooperation and/or with the presence of a direct link where multiple thresholds are needed. By combining the multiple-SNR threshold method with a selection of the best relaying link, a high spectral-efficiency cooperative transmission scheme is further presented. Simulation results verify the theoretical analysis and demonstrate performance advantage of our proposed schemes over the existing ones.

  3. 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.

  4. Reliability of spike and burst firing in thalamocortical relay cells.

    Science.gov (United States)

    Zeldenrust, Fleur; Chameau, Pascal J P; Wadman, Wytse J

    2013-12-01

    The reliability and precision of the timing of spikes in a spike train is an important aspect of neuronal coding. We investigated reliability in thalamocortical relay (TCR) cells in the acute slice and also in a Morris-Lecar model with several extensions. A frozen Gaussian noise current, superimposed on a DC current, was injected into the TCR cell soma. The neuron responded with spike trains that showed trial-to-trial variability, due to amongst others slow changes in its internal state and the experimental setup. The DC current allowed to bring the neuron in different states, characterized by a well defined membrane voltage (between -80 and -50 mV) and by a specific firing regime that on depolarization gradually shifted from a predominantly bursting regime to a tonic spiking regime. The filtered frozen white noise generated a spike pattern output with a broad spike interval distribution. The coincidence factor and the Hunter and Milton measure were used as reliability measures of the output spike train. In the experimental TCR cell as well as the Morris-Lecar model cell the reliability depends on the shape (steepness) of the current input versus spike frequency output curve. The model also allowed to study the contribution of three relevant ionic membrane currents to reliability: a T-type calcium current, a cation selective h-current and a calcium dependent potassium current in order to allow bursting, investigate the consequences of a more complex current-frequency relation and produce realistic firing rates. The reliability of the output of the TCR cell increases with depolarization. In hyperpolarized states bursts are more reliable than single spikes. The analytically derived relations were capable to predict several of the experimentally recorded spike features.

  5. DIGITAL FILTERS IMPLEMENTATION IN MICROPROCESSOR-BASED RELAY PROTECTION

    Directory of Open Access Journals (Sweden)

    Yu. V. Rumiantsev

    2016-01-01

    Full Text Available This article presents the implementation of digital filters used in digital relay protection current measuring elements. Mathematical descriptions of the considered digital filters as well as the computer programs for their coefficients calculation are described. It has been shown that in order to reliable estimate the digital filter performance its input signals waveforms must be close to the actual secondary current waveform of the current transformer to which the digital protection with the estimated digital filter is connected. For these purposes in MatLab–Simulink dynamic simulation environment the power system and the current measuring element models were developed. Performed calculations allowed to reveal that the exponentially decaying DC component which in some cases contains in primary fault current drives the current transformer core into saturation even when its nominal parameters are not exceeded. This results in distortion of the current transformer secondary current which in this case contains higher and inter-harmonics. Moreover, such harmonic content is not completely taking into account during coefficients calculation of the considered digital filters what results in signal magnitude estimation inaccuracy. Comparison of the digital filters response to the above-mentioned input signals allowed to find out such digital filter implementations which enable signal magnitude estimation with a minimum error. Ways of filtering quality improvement concerned with the window functions are proposed. Thus, the joint usage of digital filter and Hamming window allows to achieve the zero value of the signal magnitude gain factor in high-frequency range and substantially suppress all spectral components above 100 Hz. The increasing of the signal magnitude settling time in this case can be reduced by choosing the most optimal parameters of the all components of the current measuring element.

  6. MGS and Odyssey - Relay Satellites for the MER Mission

    Science.gov (United States)

    Esposito, Pasquale B.; Bhat, R.; Demcak, S.; Ardakab, S.; Breeden, J.; Helfrich, C.; Jefferson, D.; Stauch, J.

    2004-01-01

    Both Mars Global Surveyor (MGS) and Mars Odyssey are currently in low altitude, nearly circular and highly inclined orbits about Mars. Thus, they are available and compatible to serve as relay satellites for the Mars Exploration Rover (MER) mission. Consequently, the MER project developed requirements for MGS to be overhead, at a specific time with a 30 second tolerance, during the atmospheric entry, descent and landing (EDL) phase of both MER vehicles. The result, after execution of a single orbit synchronization maneuver (OSM) on 10/03/03, 92.4 days or 1130 orbits before Spirit's EDL, was that MGS was over Spirit 8 seconds past the required time. This maneuver, with a delta-velocity of 0.534 m/s, caused the orbital period to change by 3.34 s and resulted in a time-phasing change of 62 min 19 s in order to achieve the EDL overflight. Based on the navigation and execution of an OSM on 01/04/04, MGS was overhead for the Opportunity EDL on 01/25/04,3.5 seconds after the required epoch. Requirements also existed for the Odyssey over-flight of the MER rovers after landing and various equipment deployments had been completed. Thus, these requirements were that Odyssey should rise no earlier than specified times with respect to each of the landing sites. The Odyssey over-flights of both Spirit and Opportunity on sol 1 were equally successful. This paper will present the navigation plan, trajectory propagation accuracy and maneuver execution for the successful MGS and Odyssey over-flights of both the MER rovers.

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Francesco Chiti

    2017-12-01

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

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

    KAUST Repository

    Liang Yang,

    2013-06-01

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

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

    KAUST Repository

    Hussain, Syed Imtiaz

    2010-06-01

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

  11. THE SCHEME WITH THE MULTIPURPOSE RELAY FOR ECONOMY OF ELECTRIC ENERGY IN TO GRAIN THROWER

    Directory of Open Access Journals (Sweden)

    N. A. Mazukha

    2015-01-01

    Full Text Available The scheme for economy of electric energy during the work for an example of a grain thrower of the ZME 60 type (Voronezh Region, Semiluki on grain flows in rural economy is offered. Grain thrower can carry out the following technological operations: loading of grain in vehicles; loading and unloading of grain stores; mechanical shoveling of grain on the open areas; separation of grain with office of light impurity. In the scheme the relay 3UG3521/22t (SIEMENS firm is used. The relay can carry out multipurpose protection of engines and comprises the relay of the maximum current, the relay of the minimum current, a timer and the index relay. Temporary charts of the relay 3UG3521/22t are provided in the mode "without preservation" and in the mode with "preservation" for the OVER functions (reaction to growth of current and the UNDER function (reaction to recession of current. Use of the relay 3UG3521/22t allowed to receive protection at long start-up of electric motors, at an overload of electric motors, when idling (for economy of electric energy due to automatic shutdown of the conveyor and at break or jamming of the conveyor. Besides, in the scheme it is offered the multipurpose relay of tension (the relay of control of phases for protection of three engines of a grain thrower at not full-phase modes of a power line. The economy of electric energy can be received in case of, for example, the late actions of the operator for timely shutdown of the engine of a self-feed upon transition of a grain thrower to idling. In practice transition of a grain thrower to the mode of idling is quite often possible in process of reduction of amount of the thrown grain on a platform before a grain thrower. In practice transition of a grain thrower to the mode of idling is quite often possible in process of reduction of amount of the thrown grain on a platform before a grain thrower. The offered electric circuit can be used in the grain thrower and grain loaders

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

    KAUST Repository

    Choi, Seyeong

    2017-11-15

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

  13. 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.

  14. RoCoMAR: Robots’ Controllable Mobility Aided Routing and Relay Architecture for Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Seokhoon Yoon

    2013-07-01

    Full Text Available In a practical deployment, mobile sensor network (MSN suffers from a low performance due to high node mobility, time-varying wireless channel properties, and obstacles between communicating nodes. In order to tackle the problem of low network performance and provide a desired end-to-end data transfer quality, in this paper we propose a novel ad hoc routing and relaying architecture, namely RoCoMAR (Robots’ Controllable Mobility Aided Routing that uses robotic nodes’ controllable mobility. RoCoMAR repeatedly performs link reinforcement process with the objective of maximizing the network throughput, in which the link with the lowest quality on the path is identified and replaced with high quality links by placing a robotic node as a relay at an optimal position. The robotic node resigns as a relay if the objective is achieved or no more gain can be obtained with a new relay. Once placed as a relay, the robotic node performs adaptive link maintenance by adjusting its position according to the movements of regular nodes. The simulation results show that RoCoMAR outperforms existing ad hoc routing protocols for MSN in terms of network throughput and end-to-end delay.

  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. On Outage Probability and Diversity-Multiplexing Tradeoff in MIMO Relay Channels

    CERN Document Server

    Loyka, Sergey

    2011-01-01

    Fading MIMO relay channels are studied analytically, when the source and destination are equipped with multiple antennas and the relays have a single one. Compact closed-form expressions are obtained for the outage probability under i.i.d. and correlated Rayleigh-fading links. Low-outage approximations are derived, which reveal a number of insights, including the impact of correlation, of the number of antennas, of relay noise and of relaying protocol. The effect of correlation is shown to be negligible, unless the channel becomes almost fully correlated. The SNR loss of relay fading channels compared to the AWGN channel is quantified. The SNR-asymptotic diversity-multiplexing tradeoff (DMT) is obtained for a broad class of fading distributions, including, as special cases, Rayleigh, Rice, Nakagami, Weibull, which may be non-identical, spatially correlated and/or non-zero mean. The DMT is shown to depend not on a particular fading distribution, but rather on its polynomial behavior near zero, and is the same ...

  17. Advanced relay testing and signal processing software for two-terminal digital simulator

    Energy Technology Data Exchange (ETDEWEB)

    Kezunovic, M.; Chen, Q. [Texas A and M Univ., College Station, TX (United States). Dept. of Electrical Engineering

    1996-10-01

    Current utility practice for relay testing is to use portable test-sets capable of generating steady-state test waveforms. Recent studies, however, have indicated that steady-state tests are not sufficient if the full behavior of a relay is to be evaluated. Digital simulator concept is one of the most desirable solutions to this problem. It includes hardware and software that allow both phasor and transient testing of protective relays. This paper describes relay testing and signal processing software for a newly developed two-terminal digital simulator. The simulator development was initiated in late 1989 and has resulted in several modeling and simulation studies, as well as simulator hardware and software designs. The software discussed in this paper was installed for beta-site testing at the department of Energy--Western Area Power Administration (WAPA) in the Summer of 1995. It has also been extensively evaluated at Texas A and M University, with the close cooperation of Houston Light and Power Company (HL and P). This software is capable of performing data conversion, signal processing, signal analysis, relay testing, and test result analysis using various transient data formats such as COMTRADE (IEEE COMmon format for TRAnsient Data Exchange), electromagnetic transient program (EMTP), and digital fault recorder (DFR). In this paper, the digital simulator hardware configuration is presented first. The software requirement and software configuration are discussed then. Next, the new software developments are described. Examples of the software applications are also outlined.

  18. 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.

  19. Topological Interference Management for K-User Downlink Massive MIMO Relay Network Channel.

    Science.gov (United States)

    Selvaprabhu, Poongundran; Chinnadurai, Sunil; Li, Jun; Lee, Moon Ho

    2017-08-17

    In this paper, we study the emergence of topological interference alignment and the characterizing features of a multi-user broadcast interference relay channel. We propose an alternative transmission strategy named the relay space-time interference alignment (R-STIA) technique, in which a K -user multiple-input-multiple-output (MIMO) interference channel has massive antennas at the transmitter and relay. Severe interference from unknown transmitters affects the downlink relay network channel and degrades the system performance. An additional (unintended) receiver is introduced in the proposed R-STIA technique to overcome the above problem, since it has the ability to decode the desired signals for the intended receiver by considering cooperation between the receivers. The additional receiver also helps in recovering and reconstructing the interference signals with limited channel state information at the relay (CSIR). The Alamouti space-time transmission technique and minimum mean square error (MMSE) linear precoder are also used in the proposed scheme to detect the presence of interference signals. Numerical results show that the proposed R-STIA technique achieves a better performance in terms of the bit error rate (BER) and sum-rate compared to the existing broadcast channel schemes.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    KAUST Repository

    Rabie, Khaled M.

    2017-02-07

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

  5. 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.

  6. 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.

  7. Improper Gaussian signaling in full-duplex relay channels with residual self-interference

    KAUST Repository

    Gaafar, Mohamed

    2016-07-26

    We study the potential employment of improper Gaussian signaling (IGS) in full-duplex cooperative settings with residual self-interference (RSI). IGS is recently shown to outperform traditional proper Gaussian signaling (PGS) in several interference-limited channel settings. In this work, IGS is employed in an attempt to alleviate the RSI adverse effect in full-duplex relaying (FDR). To this end, we derive a tight upper bound expression for the end-to-end outage probability in terms of the relay signal parameters represented in its power and circularity coefficient. We further show that the derived upper bound is either monotonic or unimodal in the relay\\'s circularity coefficient. This result allows for easily locating the global optimal point using known numerical methods. Based on the analysis, IGS allows FDR systems to operate even with high RSI. It is shown that, while the communication totally fails with PGS as the RSI increases, the IGS outage probability approaches a fixed value that depends on the channel statistics and target rate. The obtained results show that IGS can leverage higher relay power budgets than PGS to improve the performance, meanwhile it relieves its RSI impact via tuning the signal impropriety. © 2016 IEEE.

  8. Ensuring Control Processes Quality in Relay System Without Speed Sensor

    Directory of Open Access Journals (Sweden)

    R. P. Simonyants

    2014-01-01

    Full Text Available The paper considers topical issues of constructing relay systems to control spacecraft attitude and stabilization with no speed sensors (SS owing to use of internal feedback (IF. To research this system by point methods, e.g. a point mapping method, is difficult because of the need to solve the transcendent equations containing parameters both of control object and of IF. We propose the “diagram of superimpositions" (DS method based on topological transformations of the phase space and introduction of a relative time, which enables us to solve engineering problems in analysis and synthesis effectively.The concept of the method is based on the assertion that there is an unambiguous dependence between quality of dynamical regimes in the control system and characteristics of IF transition function. To justify the method a simplified mathematical model of spacecraft motion is applied. The following conditions are accepted: perturbations can be neglected; when the control function is activated, the signal of IF is equal to zero. To the phase surfaces are applied topological symmetry transformations, alignment and projection onto the plane with one of its coordinates being the relative time.The paper gives specific examples of systems with aperiodic feedback (AF for two versions of parameters to satisfy the requirements: I – in quality of self-oscillation mode (by pulse width in the limit cycle; II – in quality of transition process (lack of sliding modes. It is shown that the requirements II and I are contradictory for the system with AF while the sliding modes are unacceptable.It is shown that DS can be used to synthesize the IF to meet requirements of both steady and transient processes consistently. Using the IF it is possible to implement the shutdown laws of the control action on the DS without SS, the same as in case of using the SS. It is shown that in sliding modes transient processes poor in quality can be completely eliminated by

  9. 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.

  10. High Excitation Transfer Efficiency from Energy Relay Dyes in Dye-Sensitized Solar Cells

    KAUST Repository

    Hardin, Brian E.

    2010-08-11

    The energy relay dye, 4-(Dicyanomethylene)-2-methyl-6-(4- dimethylaminostyryl)-4H-pyran (DCM), was used with a near-infrared sensitizing dye, TT1, to increase the overall power conversion efficiency of a dye-sensitized solar cell (DSC) from 3.5% to 4.5%. The unattached DCM dyes exhibit an average excitation transfer efficiency (EÌ?TE) of 96% inside TT1-covered, mesostructured TiO2 films. Further performance increases were limited by the solubility of DCM in an acetonitrile based electrolyte. This demonstration shows that energy relay dyes can be efficiently implemented in optimized dye-sensitized solar cells, but also highlights the need to design highly soluble energy relay dyes with high molar extinction coefficients. © 2010 American Chemical Society.

  11. Relay-Assisted Partial Packet Recovery with IDMA Method in CDMA Wireless Network

    CERN Document Server

    Luo, Zhifeng; Wong, Albert Kai-sun; Qiu, Shuisheng

    2010-01-01

    Automatic Repeat Request (ARQ) is an effective technique for reliable transmission of packets in wireless networks. In ARQ, however, only a few erroneous bits in a packet will cause the entire packet to be discarded at the receiver. In this case, it's wasteful to retransmit the correct bit in the received packet. The partial packet recovery only retransmits the unreliable decoded bits in order to increase the throughput of network. In addition, the cooperative transmission based on Interleave-division multiple-access (IDMA) can obtain diversity gains with multiple relays with different locations for multiple sources simultaneously. By exploring the diversity from the channel between relay and destination, we propose a relay-assisted partial packet recovery in CDMA wireless network to improve the performance of throughput. In the proposed scheme, asynchronous IDMA iterative chip-by-chip multiuser detection is utilized as a method of multiple partial recovery, which can be a complementarity in a current CDMA ne...

  12. Outage Probability for ARQ Decode-and-Forward Relaying under Packet-Rate Fading

    Science.gov (United States)

    Lee, Sangkook; Su, Weifeng; Batalama, Stella; Matyjas, John D.

    In this paper, a new analytical approach is developed for the evaluation of the outage probability of decode-and-forward (DF) automatic-repeat-request (ARQ) relaying under packet-rate fading (fast fading) channels. Based on this approach, a closed-form asymptotically tight (as SNR → ∞) approximation of the outage probability is derived, and the diversity order of the DF cooperative ARQ relay scheme is shown to be equal to 2L - 1, where L is the maximum number of ARQ retransmissions. The closed-form expression clearly shows that the achieved diversity is partially due to the DF cooperative relaying and partially due to the fast fading nature of the channels (temporal diversity). Numerical and simulation studies illustrate the theoretical developments.

  13. Using Distributed Rotations for a Low-Complexity Dynamic Decode-and-Forward Relay Protocol

    CERN Document Server

    Hucher, Charlotte

    2011-01-01

    In this paper, we propose to implement the dynamic decode-and-forward (DDF) protocol with distributed rotations. In addition to being the first minimum-delay implementation of the DDF protocol proposed for any number of relays, this technique allows to exploit cooperative diversity without inducing the high decoding complexity of a space-time code. The analysis of outage probabilities for different number of relays and rotations shows that the performance of this technique is close to optimal. Moreover, a lower-bound on the diversity-multiplexing gain tradeoff (DMT) is provided in the case of a single relay and two rotations. This lower-bound reaches the optimal DDF's DMT when the frame-length grows to infinity, which shows that even a small number of rotations is enough to obtain good performance.

  14. 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.

  15. Multi-hop Relaying: An End-to-End Delay Analysis

    KAUST Repository

    Chaaban, Anas

    2015-12-01

    The impact of multi-hopping schemes on the communication latency in a relay channel is studied. The main aim is to characterize conditions under which such schemes decrease the communication latency given a reliability requirement. Both decode-forward (DF) and amplify-forward (AF) with block coding are considered, and are compared with the point-to-point (P2P) scheme which ignores the relay. Latency expressions for the three schemes are derived, and conditions under which DF and AF reduce latency are obtained for high signal-to-noise ratio (SNR). Interestingly, these conditions are more strict when compared to the conditions under which the same multi-hopping schemes achieve higher long-term (information-theoretic) rates than P2P. It turns out that the relation between the sourcedestination SNR and the harmonic mean of the SNR’s of the channels to and from the relay dictates whether multi-hopping reduces latency or not.

  16. 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.

  17. Optimization of Resource Allocation in Multihop HARQ Relay Networks with a Delay Constraint

    Directory of Open Access Journals (Sweden)

    Han Jun-Mei

    2017-01-01

    Full Text Available By minimizing the outage probability, optimization is carried out in this paper to find joint optimal power allocation (OPA and relay placement (ORP for multihop relay networks adopting Hybrid Automatic Repeat reQuest (HARQ. Different from previous works, the joint OPA and ORP is analysed under generalized fading channels with the constraint on total transmit power, end-to-end relaying distance and maximum transmission number (delay. The simulation results demonstrate that for different fixed number of nodes and fading models, there are preferred deployments depending on path loss exponent and power retransmission strategy. By employing multiple retransmission round which can improve the reliability and energy efficiency without significant overhead, the end-to-end outage probability is no longer bounded by that of the weaker hop, i.e., the hop with a poor channel condition. The proposed strategy provides a dramatic improvement for the end-to-end outage probability by compensating the channel difference.

  18. 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.

  19. 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.

  20. Wide Area Protection Scheme Preventing Cascading Events based on Improved Impedance relay

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Sun, Haishun

    2013-01-01

    Load flow transferring after an initial contingency is regarded as one of the main reasons of causing unexpected cascading trips. A multi agent system (MAS) based wide area protection strategy is proposed in this paper to predict the load flow transferring from the point of view of impedance relays......, and prevent the unexpected relay operations accordingly. The variations of node injections during the post fault transient period will be also considered in the prediction algorithm. The power system of Eastern Denmark modeled in real time digital simulator (RTDS) will be used to demonstrate the proposed...... strategy. The simulation results indicate this strategy can successfully predict and prevent the unexpected relay operation caused by load flow transferring....

  1. Cooperative jamming power control to enhance secrecy communications of AF Relaying systems for Rayleigh fading channel

    KAUST Repository

    Park, Kihong

    2012-09-01

    In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods. © 2012 IEEE.

  2. Energy-Efficient Opportunistic Transmission Scheduling for Sparse Sensor Networks with Mobile Relays

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2016-01-01

    Full Text Available Wireless sensing devices have been widely used in civilian and military applications over the past decade. In some application scenarios, the sensors are sparsely deployed in the field and are costly or infeasible to have stable communication links for delivering the collected data to the destined server. A possible solution is to utilize the motion of entities that are already present in the environment to provide opportunistic relaying services for sensory data. In this paper, we design and propose a new scheduling scheme that opportunistically schedules data transmissions based on the optimal stopping theory, with a view of minimizing the energy consumption on network probes for data delivery. In fact, by exploiting the stochastic characteristics of the relay motion, we can postpone the communication up to an acceptable time deadline until the best relay is found. Simulation results validate the effectiveness of the derived optimal strategy.

  3. Asynchronous Two-Way Relaying Networks Using Distributed Differential Space-Time Coding

    Directory of Open Access Journals (Sweden)

    Minjie Qian

    2015-01-01

    Full Text Available A signal detection scheme is proposed for two-way relaying network (TWRN using distributed differential space-time coding (DDSTC under imperfect synchronization. Unlike most of existing work, which assumed perfect synchronization and channel state information (CSI at all nodes, a more realistic scenario is investigated here by considering the signals transmitted from the two source nodes arriving at the relay not exactly at the same time due to the distributed nature of the nodes, and no CSI is available at any node. The proposed signal detection scheme is then demonstrated to remove the imperfect synchronization effect significantly through simulation results. Furthermore, pairwise error probability (PEP of the asynchronous TWRN is analyzed and derived for both source nodes. Based on the simplified PEP expression, an optimum power allocation (OPA scheme is then determined to further improve the whole system performance, when neither the source nor the relay has any knowledge of the CSI.

  4. 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.

  5. On achievable rate of two-way relaying cognitive radio with space alignment

    KAUST Repository

    Sboui, Lokman

    2015-09-11

    We study a multiple-antenna two-way relaying (TWR) spectrum sharing system. A space alignment (SA) technique is adopted by the secondary users (SU\\'s) to avoid interference with the primary users (PU\\'s). We derive the optimal power allocation that maximizes the TWR achievable sum-rate of the SU while respecting the total power budget and the relay power constraints. In the numerical results, we quantify the sum-rate gain of using the SA in the TWR CR and we show that the SU sum-rate is very limited when the relay power is low or the PU\\'s power and its resulting interference is high. © 2015 IEEE.

  6. Data Relay Board with Protocol for High-Speed, Free-Space Optical Communications

    Science.gov (United States)

    Wright, Malcolm; Clare, Loren; Gould, Gary; Pedyash, Maxim

    2004-01-01

    In a free-space optical communication system, the mitigation of transient outages through the incorporation of error-control methods is of particular concern, the outages being caused by scintillation fades and obscurants. The focus of this innovative technology is the development of a data relay system for a reliable high-data-rate free-spacebased optical-transport network. The data relay boards will establish the link, maintain synchronous connection, group the data into frames, and provide for automatic retransmission (ARQ) of lost or erred frames. A certain Quality of Service (QoS) can then be ensured, compatible with the required data rate. The protocol to be used by the data relay system is based on the draft CCSDS standard data-link protocol Proximity-1, selected by orbiters to multiple lander assets in the Mars network, for example. In addition to providing data-link protocol capabilities for the free-space optical link and buffering the data, the data relay system will interface directly with user applications over Gigabit Ethernet and/or with highspeed storage resources via Fibre Channel. The hardware implementation is built on a network-processor-based architecture. This technology combines the power of a hardware switch capable of data switching and packet routing at Gbps rates, with the flexibility of a software- driven processor that can host highly adaptive and reconfigurable protocols used, for example, in wireless local-area networks (LANs). The system will be implemented in a modular multi-board fashion. The main hardware elements of the data relay system are the new data relay board developed by Rockwell Scientific, a COTS Gigabit Ethernet board for user interface, and a COTS Fibre Channel board that connects to local storage. The boards reside in a cPCI back plane, and can be housed in a VME-type enclosure.

  7. Performance analysis of power swing blocking feature in ABB 670 series impedance relays

    Directory of Open Access Journals (Sweden)

    Maciej Łosiński

    2012-12-01

    Full Text Available This paper presents test results of a distance protection’s PSD power swing detection feature in ABB 670 series relays. A RED670 relay was tested, which is part of the hydroelectric set protection in Żarnowiec Pumped Storage Plant. The power swing blocking feature’s performance was analysed on the basis of the results of object tests made with an Omicron digital tester. Also presented are simulation results that illustrate the PSD feature’s response to power swings caused by a disturbance in the power system. It is also shown how a distance protection may react to the same fault, depending on its settings.

  8. Application of DIgSILENT POWERFACTORY software for modeling of industrial network relay protection system

    Directory of Open Access Journals (Sweden)

    Sučević Nikola

    2016-01-01

    Full Text Available This paper presents modeling of industrial network relay protection system using DIgSILENT PowerFactory software. The basis for the model of protection system is a model of a single substation in an industrial network. The paper presents the procedure for modeling of protective devices of 6 kV asynchronous motors, 6/0,4 kV/kV transformers as well as protection in the bus coupler and busbar protection. Protective relay system response for the simulated disturbances is shown in the paper.

  9. The Use of Intelligent Relays for the Sewer Cleaning Vehicle Control and Automation

    Directory of Open Access Journals (Sweden)

    O. Chiver

    2012-06-01

    Full Text Available The paper presents the way in which the electrical control and automation system of the 5 mc combined sewer and gully cleaning vehicle equipped by a local company was designed, using the intelligent relay of the easy 700 type of Moeller (Eaton company. The control of all the equipments is performed locally from the control panel and some of them can also by remote controlled by means of the radio waves. The program required by the intelligent relay was created, tested and implemented with the help of the dedicated software easy-soft 6, developed by the manufacturing company.

  10. On the jamming power allocation for secure amplify-and-forward relaying via cooperative jamming

    KAUST Repository

    Park, Kihong

    2013-09-01

    In this paper, we investigate secure communications in two-hop wireless relaying networks with one eavesdropper. To prevent the eavesdropper from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as cooperative jamming. This jamming noise helps protecting the source message from being captured reliably at the eavesdropper, while the destination cancels its self-intended noise. According to the channel information available at the destination, we derive three jamming power allocation strategies to minimize the outage probability of the secrecy rate. In addition, we derive analytic results quantifying the jamming power consumption of the proposed allocation methods. © 1983-2012 IEEE.

  11. A minimum bit error-rate detector for amplify and forward relaying systems

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2012-05-01

    In this paper, a new detector is being proposed for amplify-and-forward (AF) relaying system when communicating with the assistance of L number of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the system. The complexity of the system is further reduced by implementing this detector adaptively. The proposed detector is free from channel estimation. Our results demonstrate that the proposed detector is capable of achieving a gain of more than 1-dB at a BER of 10 -5 as compared to the conventional minimum mean square error detector when communicating over a correlated Rayleigh fading channel. © 2012 IEEE.

  12. 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.

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

    KAUST Repository

    Tourki, Kamel

    2010-11-01

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

  14. 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.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    For WLAN systems in which relaying is exploited for improving throughput performance, node mobility and in- formation collection delays can have a significant impact on the performance of a relay selection scheme. This paper analyzes this influence on the decision process using a previously...... developed Markov Chain model for a realistic indoor scenario that is based on ray-tracing enriched measurements from the WHERE2 project. These results are furthermore compared to results obtained using an idealistic path loss model, and it is shown that the performance impact of node mobility...

  16. The Capacity Region of Restricted Multi-Way Relay Channels with Deterministic Uplinks

    CERN Document Server

    Ong, Lawrence

    2012-01-01

    This paper considers the multi-way relay channel (MWRC) where multiple users exchange messages via a single relay. The capacity region is derived for a special class of MWRCs where (i) the uplink and the downlink are separated in the sense that there is no direct user-to-user links, (ii) the channel is restricted in the sense that each user's transmitted channel symbols can depend on only its own message, but not on its received channel symbols, and (iii) the uplink is any deterministic function.

  17. Pilot power optimization for AF relaying using maximum likelihood channel estimation

    KAUST Repository

    Wang, Kezhi

    2014-09-01

    Bit error rates (BERs) for amplify-and-forward (AF) relaying systems with two different pilot-symbol-aided channel estimation methods, disintegrated channel estimation (DCE) and cascaded channel estimation (CCE), are derived in Rayleigh fading channels. Based on these BERs, the pilot powers at the source and at the relay are optimized when their total transmitting powers are fixed. Numerical results show that the optimized system has a better performance than other conventional nonoptimized allocation systems. They also show that the optimal pilot power in variable gain is nearly the same as that in fixed gain for similar system settings. andcopy; 2014 IEEE.

  18. 75 FR 29914 - Telecommunications Relay Services, Speech-to-Speech Services, E911 Requirements for IP-Enabled...

    Science.gov (United States)

    2010-05-28

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 64 Telecommunications Relay Services, Speech-to-Speech Services, E911 Requirements for... requirements associated with the Commission's Telecommunications Relay Services, ] Speech-to-Speech Services...

  19. 75 FR 26701 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-05-12

    ...; DA 10-761] Telecommunications Relay Services and Speech-to-Speech Services for Individuals With... Telecommunications Relay Services (TRS) Fund (Fund) for the period of July 1, 2010, through June 30, 2011 (2010-2011... should be recalculated based on data reflecting the actual costs of providing VRS. Telecommunications...

  20. 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.

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

    KAUST Repository

    Lei, Hongjiang

    2017-10-02

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

  2. 77 FR 65526 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2012-10-29

    ... COMMISSION 47 CFR Part 64 Telecommunications Relay Services and Speech-to-Speech Services for Individuals... comment on matters related to access technology and enhanced database operations for video relay service... be in a position to set new rates as it moves forward with the next phase of VRS reform, it also...

  3. A fluid model for a relay node in an ad-hoc network: the case of heavy-tailed input

    NARCIS (Netherlands)

    R. Bekker (Rene); M.R.H. Mandjes (Michel)

    2007-01-01

    textabstractRelay nodes in an ad-hoc network can be modelled as fluid queues, in which the available service capacity is shared by the input and output. In this paper such a relay node is considered; jobs arrive according to a Poisson process and bring along a random amount of work. The total

  4. Exact Performance Analysis of Partial Relay Selection Based on Shadowing Side Information over Generalized Composite Fading Channels

    CERN Document Server

    Yilmaz, Ferkan

    2011-01-01

    Relay technology has recently gained great interest in millimeter wave (60 GHz or above) radio frequencies as a promising transmission technique improving the quality of service, providing high data rate, and extending the coverage area without additional transmit power in deeply shadowed wireless environments. The performance of relay-based systems depends considerably on which relay selection protocols are used. These protocols are typically using the channel side information (CSI). Specifically, the relay terminal (RT) is chosen among all available RTs by a centralized entity (CE) which receives all RTs' CSI via feedback channels. However, in the millimeter wave radio frequencies, the rate of the variation of the CSI is much higher than that of a classical system operating in 6 GHz frequencies under the same mobility conditions, which evidently results in a serious problem causing outdated (inaccurate) CSI for the relay selection protocol at the CE since the feedback channels have a backhaul / transmission...

  5. 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

    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....... 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...... 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...

  6. Precoding Design of MIMO Amplify-and-Forward Communication System With an Energy Harvesting Relay and Possibly Imperfect CSI

    KAUST Repository

    Benkhelifa, Fatma

    2017-03-02

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) in a Multiple-Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication system where the relay is an energy harvesting (EH) node and harvests the energy the signals transmitted from the source. The harvested energy is partially used to forward signals from the source to the destination, and the remaining energy is stored for other usages. The SWIPT in relay-assisted communication is interesting as long as the relay stores energy from the source and the destination receives successfully the data from the source. In this context, we propose to investigate the source and relay precoders that characterize the relationship between the achievable stored energy at the relay and the achievable sourceto- destination rate, namely the rate-stored energy (R-E) tradeo region. First, we consider the ideal scheme where there is the simultaneous operation of the EH and ID receivers at the relay. Then, we consider practical schemes such as the power splitting (PS) and the time switching (TS) that separate the operation of EH and information decoding (ID) receivers over power domain or time domain, respectively. Moreover, we study the case of imperfect channel state information (CSI) at the relay and the destination and characterize its impact on the achievable R-E region. Through the simulation results, we show the eect of the position of the relay and the channel uncertainty on the achievable R-E regions of all the schemes when the used energy at the relay is constant or variable. We also show that, although it provides an outer bound on the achievable rate-energy region in one-hop MIMO systems, the ideal scheme provides only an upper bound on the maximum achievable end-to-end rate and not an outer bound on the R-E region.

  7. Effect of soybean relayed into yam miniset/maize intercrop on the ...

    African Journals Online (AJOL)

    The effect of four varieties of soybean (TGX 1019-2 EB, TGX 1448 – 2E, TGX 1740 – 2F. TGX 1440 – IE) relayed into yam ministett/maize system on the yield of component crops and soil fertility of yam based system was investigated at National Root Crops Research Institute, substation Otobi, Benue State, Nigeria. Soybean ...

  8. Performance of relay-enabled uplink in cellular networks - a flow level analysis

    NARCIS (Netherlands)

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

    2009-01-01

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

  9. Achievable Rates of UAV-Relayed Cooperative Cognitive Radio MIMO Systems

    KAUST Repository

    Sboui, Lokman

    2017-04-19

    We study the achievable rate of an uplink MIMO cognitive radio system where the primary user (PU) and the secondary user (SU) aim to communicate to the closest primary base station (BS) via a multi-access channel through the same unmanned aerial vehicle (UAV) relay. The SU message is then forwarded from the primary BS to the secondary network with a certain incentive reward as a part of the cooperation protocol between both networks. A special linear precoding scheme is proposed to enable the SU to exploit the PU free eigenmodes. We analyze two scenarios in which the UAV relay gain matrix is either fixed or optimized. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting power budget, interference, and relay power constraints. Numerical results highlight the cognitive rate gain of our proposed scheme with respect to various problem parameters. We also highlight the effect of UAV altitude on the SU and PU rates. Finally, when the relay matrix is optimized, we show that the PU rate is remarkably enhanced and that the SU rate is only improved at high power regime.

  10. Mobile relays for enhanced broadband connectivity in high speed train systems

    KAUST Repository

    Yaacoub, Elias E.

    2014-09-01

    With the introduction of wireless modems and smart phones, the passenger transport industry is witnessing a high demand to ensure not only the safety of the trains, but also to provide users with Internet access all the time inside the train. When the Mobile Terminal (MT) communicates directly with the Base Station (BS), it will experience a severe degradation in the Quality of Service due to the path loss and shadowing effects as the wireless signal is traveling through the train. In this paper, we study the performance in the case of relays placed on top of each train car. In the proposed approach, these relays communicate with the cellular BS on one hand, and with the MTs inside the train cars on the other hand, using the Long Term Evolution (LTE) cellular technology. A low complexity heuristic LTE radio resource management approach is proposed and compared to the Hungarian algorithm, both in the presence and absence of the relays. The presence of the relays is shown to lead to significant enhancements in the effective data rates of the MTs. In addition, the proposed resource management approach is shown to reach a performance close to the optimal Hungarian algorithm. © 2014 Elsevier B.V.

  11. Performance analysis of uplink packet schedulers in cellular networks with relaying

    NARCIS (Netherlands)

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

    Deployment of intermediate relay nodes in cellular networks, e,g, UMTS/ HSPA, has been proposed for service enhancement, which is of particular importance for uplink users at the cell edge suffering from low power capacity and relatively poor channel conditions. In this paper, we propose and

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  13. Towards a Framework for Modelling and Verification of Relay Interlocking Systems

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth

    2010-01-01

    This paper describes a framework currently under development for modelling, simulation, and verification of relay interlocking systems as used by the Danish railways. The framework is centred around a domain-specific language (DSL) for describing such systems, and provides (1) a graphical editor ...

  14. Temperature-mediated developmental delay may limit yield of cotton in relay intercrops with wheat

    NARCIS (Netherlands)

    Zhang, L.Z.; Werf, van der W.; Zhang, S.; Li, B.; Spiertz, J.H.J.

    2008-01-01

    In the Yellow River valley of China, more then 1.4 million ha of cotton are grown as relay intercrops with wheat. Cotton is sown in April when winter wheat is already in the reproductive phase; thus, a wheat crop with a fully developed canopy will compete for resources with cotton plants in the

  15. An Optimal Transmission Strategy for Joint Wireless Information and Energy Transfer in MIMO Relay Channels

    Directory of Open Access Journals (Sweden)

    Dingcheng Yang

    2015-01-01

    Full Text Available An optimal resource allocation strategy for MIMO relay system is considered in simultaneous wireless information and energy transfer network, where two users with multiple antennas communicate with each other assisted by an energy harvesting MIMO relay that gathers energy from the received signal by applying time switching scheme and forwards the received signal by using the harvesting energy. It is focused on the precoder design and resource allocation strategies for the system to allocate the resources among the nodes in decode-and-forward (DF mode. Specifically, optimal precoder design and energy transfer strategy in MIMO relay channel are firstly proposed. Then, we formulate the resource allocation optimization problem. The closed-form solutions for the time and power allocation are derived. It is revealed that the solution can flexibly allocate the resource for the MIMO relay channel to maximize the sum rate of the system. Simulation results demonstrated that the performance of the proposed algorithm outperforms the traditional fixed method.

  16. Opportunistic Buffered Decode-Wait-and-Forward (OBDWF) Protocol for Mobile Wireless Relay Networks

    CERN Document Server

    Wang, Rui; Huang, Huang

    2011-01-01

    In this paper, we propose an opportunistic buffered decode-wait-and-forward (OBDWF) protocol to exploit both relay buffering and relay mobility to enhance the system throughput and the end-to-end packet delay under bursty arrivals. We consider a point-to-point communication link assisted by K mobile relays. We illustrate that the OBDWF protocol could achieve a better throughput and delay performance compared with existing baseline systems such as the conventional dynamic decode-and-forward (DDF) and amplified-and-forward (AF) protocol. In addition to simulation performance, we also derived closed-form asymptotic throughput and delay expressions of the OBDWF protocol. Specifically, the proposed OBDWF protocol achieves an asymptotic throughput O(logK) with O(1) total transmit power in the relay network. This is a significant gain compared with the best known performance in conventional protocols (O(logK) throughput with O(K) total transmit power). With bursty arrivals, we show that both the stability region and...

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

    KAUST Repository

    Yilmaz, Ferkan

    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.

  18. 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.

  19. 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.

  20. 78 FR 28633 - TE Connectivity, a Subsidiary of Tyco Electronics Corporation, Relay Products Business Unit...

    Science.gov (United States)

    2013-05-15

    ... Employment and Training Administration TE Connectivity, a Subsidiary of Tyco Electronics Corporation, Relay... Assistance on March 12, 2013, applicable to workers of TE Connectivity, a subsidiary of Tyco Electronics... Hagemeyer North America were employed on-site at the Winston-Salem, North Carolina location of TE...