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In this paper, a superposition-coded concurrent decode-and-forward (DF) relaying protocol is presented. A specific scenario, where the inter-relay channel is sufficiently strong, is considered. Assuming perfect source-relay transmissions, the proposed scheme further improves the diversity performance of previously proposed repetition-coded concurre...
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Context 1
... destination, a maximal ratio combining (MRC) receiver is used for TDMA direct transmission and the stan- dard protocol, and a maximum likelihood sequence detector (MLSD) receiver is used for the concurrent DF relaying protocols. Moreover, we consider two different ways to use superposition coding in the relays. The first one (denoted as mode 1 in Fig. 5) is similar to superposition modulation [15] and we require each relay to retransmit the direct sum of its desired signal and the interference. The second one is similar to code superposition [16] (denoted as mode 2). In this case, each codeword transmitted by the relays represents the XORed version of the two ...
Context 2
... Fig. 5, it can be seen TDMA direct transmission has the worst high-SNR performance. Although repetition-coded concurrent DF relaying improves the error performance due to the signal protection by the relays, it performs worse than space-time-coded standard DF relaying since each codeword is only forwarded by one relay. Clearly, ...
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Citations
... However, this scheme targets scenarios with a long distance between the relays and thus interrelay interference is not considered. An extension of this work is discussed in [8], where the authors assume that IRI is strong (in co-located or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing trade-off performance of the system. ...
We study a cooperative network with a buffer-aided multi-antenna source, multiple half-duplex (HD) buffer-aided relays and a single destination. Such a setup could represent a cellular downlink scenario, in which the source can be a more powerful wireless device with a buffer and multiple antennas, while a set of intermediate less powerful devices are used as relays to reach the destination. The main target is to recover the multiplexing loss of the network by having the source and a relay to simultaneously transmit their information to another relay and the destination, respectively. Successive transmissions in such a cooperative network, however, cause inter-relay interference (IRI). First, by assuming global channel state information (CSI), we show that the detrimental effect of IRI can be alleviated by precoding at the source, mitigating or even fully cancelling the interference. A cooperative relaying policy is proposed that employs a joint precoding design and relay-pair selection. Note that both fixed rate and adaptive rate transmissions can be considered. For the case when channel state information is only available at the receiver side (CSIR), we propose a relay selection policy that employs a phase alignment technique to reduce the IRI. The performance of the two proposed relay pair selection policies are evaluated and compared with other state-of-the-art relaying schemes in terms of outage and throughput. The results show that the use of a powerful source can provide considerable performance improvements.
... However, this scheme targets scenarios with a long distance between the relays and thus inter-relay interference is not considered. An extension of this work is discussed in [8], where the authors assume that IRI is strong (in co-located or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing trade-off performance of the system. ...
We study a cooperative network with a buffer-aided multi-antenna source, multiple half-duplex (HD) buffer-aided relays and a single destination. Such a setup could represent a cellular downlink scenario, in which the source can be a more powerful wireless device with a buffer and multiple antennas, while a set of intermediate less powerful devices are used as relays to reach the destination. The main target is to recover the multiplexing loss of the network by having the source and a relay to simultaneously transmit their information to another relay and the destination, respectively. Successive transmissions in such a cooperative network, however, cause inter-relay interference (IRI). First, by assuming global channel state information (CSI), we show that the detrimental effect of IRI can be alleviated by precoding at the source, mitigating or even fully canceling the interference. A cooperative relaying policy is proposed that employs a joint precoding design and relay-pair selection. Note that both fixed rate and adaptive rate transmissions can be considered. For the case when channel state information is only available at the receiving side (CSIR), we propose a relay selection policy that employs a phase alignment technique to reduce the IRI. The performance of the two proposed relay pair selection policies are evaluated and compared with other state-of-the-art relaying schemes in terms of outage and throughput. The results show that the use of a powerful source can provide considerable performance improvements.
... As such, the overall error probability from the source to the destination is dominated by the error probability from the relay to the destination, and the contribution of decoding errors at the relay to the overall performance can be ignored. For simplicity of analysis, we assume error-free decoding at the relays [22,23]. Then the subsequent transmission process in the third time slot can be analyzed based on the error-free decoding at the relays. ...
Device-to-device communications have attracted much more attention recently in the realization of smart cities. In this paper, we propose a network coding (NC) scheme based on device-to-device communication for centralized wireless local area network (WLAN). In centralized WLAN scenarios, users’ communication can be implemented through multiple interaction of access points acted as relay nodes, which are similar to direct link session (DLS) protocol in IEEE 802.11 standard and we named the proposed protocol as advanced DLS scheme, where analytical performance results of the proposed two-way communication system using NC, with and without AP selection, are obtained in multi-AP cases, as well as the asymptotic results in high transmitting power. In addition, the performance comparisons of throughput, delay and collision probability of proposed scheme with IEEE 802.11 are provided in simulation, which present the advantages of centralized WLAN. By the analysis, it is found that the proposed advanced DLS scheme can achieve almost exactly the same bit error ratio performance as the optimal selection at all signal to noise ratio ranges. It is also shown that the proposed transmission scheme significantly outperform the current mode in two-way communication Nakagami channels owing to the diversity order and array gains. The proposed scheme only need little frame modification and can be compatible with the current standard. Finally, simulation results validate the theoretical analysis.
... However, this scheme targets scenarios with a long distance between the relays and thus inter-relay interference is not considered. An extension of this work is discussed in [7], where the authors assume that inter-relay interference (IRI) is strong (in co-located or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing tradeoff performance of the system. ...
... However, this scheme targets scenarios with a long distance between the relays and thus inter-relay interference is not considered. An extension of this work is discussed in [7], where the authors assume that inter-relay interference (IRI) is strong (in co-located or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing tradeoff performance of the system. ...
In this paper, we consider a cooperative network consisting of a buffer-aided multi-antenna source, multiple single-antenna half-duplex buffer-aided relays and a single-antenna destination. Such a setup could represent a cellular downlink scenario, in which the source can be a more powerful wireless device with a buffer and multiple antennas, while a set of intermediate less powerful devices are used as relays to reach the destination. For this setup we assume that the channel state information is only available at the receiving side (CSIR), being either a relay or the destination, with the ability to provide limited feedback to the transmitting side. The main target is to recover the multiplexing loss of the network by facilitating successive transmissions by having the source to transmit its information to a relay, while another relay simultaneously transmits its information to the destination. Successive transmissions, however, cause inter-relay interference (IRI). In order to mitigate the IRI, we propose a relay pair selection policy that employs a phase alignment technique. The performance of the proposed relay pair selection policy is evaluated and compared with other state-of-the-art relaying schemes in terms of outage and throughput. The numerical results demonstrate that the proposed scheme can provide considerable performance improvements.
... However, this scheme targets scenarios with a long distance between the relays and thus inter-relay interference is not considered. An extension of this work is discussed in [8], where the authors assume that IRI is strong (in co-located or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing trade-off performance of the system. ...
We study a cooperative network with a buffer-aided multi-antenna source, multiple half-duplex (HD) buffer-aided relays and a single destination. Such a setup could represent a cellular downlink scenario, in which the source can be a more powerful wireless device with a buffer and multiple antennas, while a set of intermediate less powerful devices are used as relays to reach the destination. The main target is to recover the multiplexing loss of the network by having the source and a relay to simultaneously transmit their information to another relay and the destination, respectively. Successive transmissions in such a cooperative network, however, cause inter-relay interference (IRI). First, by assuming global channel state information (CSI), we show that the detrimental effect of IRI can be alleviated by precoding at the source, mitigating or even fully canceling the interference. A cooperative relaying policy is proposed that employs a joint precoding design and relay-pair selection. Note that both fixed rate and adaptive rate transmissions can be considered. For the case when channel state information is only available at the receiving side (CSIR), we propose a relay selection policy that employs a phase alignment technique to reduce the IRI. The performance of the two proposed relay pair selection policies are evaluated and compared with other state-of-the-art relaying schemes in terms of outage and throughput. The results show that the use of a powerful source can provide considerable performance improvements.
... Extending this work to the case of multiple available relays [17,18] proposed the combination of ORS and SuR by selecting a relay-pair that achieves the maximum end-to-end SNR either by applying IC or by choosing the pair with the minimum IRI. Other works [19], propose the use of the IRI signal through superposition coding in order to achieve increased diversity gain when the receiver decodes the superposition of the IRI and the desired signal, while already having knowledge of the IRI signal from a previous reception. A further extension for SuR was given in [9,20,21] where Buffer-Aided (BA) HD relays were employed in order to provide increased freedom when selecting the relay-pair, as relays with packets residing in their buffers were considered in the selection process. ...
... On the contrary, when the IRI is weaker than the desired signal it is treated as Gaussian noise. An extension to this work is given in [19] where superposition-coding is used in order to exploit the IRI in a network where two source communicate with one destination using two relays. Assuming perfect SR transmission, the proposed scheme outperforms repetition-coding in terms of diversity by requiring only one additional time-slot. ...
In this thesis, cooperative techniques that improve the spectral-efficiency in wireless networks are investigated. Towards this end, we consider cooperative relaying as the means of spectral efficiency and propose various algorithms depending on the network characteristics. A major concern in wireless networking is the efficient mitigation of interference and thus, several schemes relying on relay selection and cancellation of the interfering signals are presented. Moreover, heterogeneity is taken into account by exploiting the relays’ capabilities and the characteristics of the network topologies.
More specifically, Chapter 1 introduces the basic elements of the thesis i.e. cooperative relaying, interference mitigation and heterogeneous wireless networks. In addition, the motivation behind the thesis is presented, as well as our contributions. Then, in Chapter 2, spectral-efficient relaying algorithms are presented based on opportunistic and successive relaying, thus formulating Successive Opportunistic Relaying (SOR). As power adaptive transmissions are employed, the selection of the best relay-pair is based on the minimum transmission power to satisfy a pre-determined spectral efficiency threshold. Furthermore, two SOR versions are given, in-band SOR that introduces Inter-Relay Interference (IRI), and out-band SOR that requires extra spectral resources to nullify
the IRI. The performance of SOR is evaluated through simulations regarding the outage probability, the average throughput, as well as the average power reduction compared to equivalent fixedpower schemes. Next, in Chapter 3, algorithms employing relays with buffering capabilities are developed. A modified version of max - link, a popular half-duplex buffer-aided algorithm, that includes the impact of direct source-destination connectivity is presented, and then, the combination of max - link, SOR and full-duplex relaying leads to the development of two hybrid schemes. Firstly, the minimum-power (min - power) algorithm based on the combination of max - link and SOR, and secondly, the Buffer-Aided successive and Full-Duplex opportunistic relaying Algorithms
(BAFDA) based on the combination of max - link, SOR and full-duplex relaying are presented. Both hybrid schemes are evaluated in terms of outage probability, average throughput, power reduction and average delay. Moreover, a suboptimal version of BAFDA is described, significantly reducing the overhead of channel estimation at the cost of decreased power-reduction. Chapter 4 presents illustrative application where the proposed algorithms are employed. More specifically, a delay-critical application requiring increased throughput and a power-efficient application aiming at increased power reduction, are presented. Examining networks where different types of relays are
employed, the proposed algorithms take into consideration the different relay characteristics and the network’s throughput and power reduction performance is evaluated. The chapter continues with the presentation of a converged satellite-terrestrial network where stratospheric relay selection (SRS) is proposed to establish the end-to-end communication. For this topology, two versions are given based on the availability of Channel State Information (CSI). Proactive SRS assumes full CSI, while reactive SRS considers CSI at the receivers. As a result, an trade-off between increased CSI
overhead and power reduction performance is created. Then, Chapter 5 examines the performance of the hybrid relay algorithms in a relay network with secrecy constraints, where eavesdroppers desire to overhear the transmitted signals. To illustrate the efficiency of the secrecy-modified relay algorithms, simulation results for applications aiming at different performance metrics, such as the achieved secrecy rate or power reduction under a secrecy rate constraint, are provided. Finally, Chapter 6 concludes this thesis and discusses several future directions.
... For a general uplink scenario with multiple users and relays, it is still a challenging problem to integrate the cooperation among the sources and the cooperation from the relays. In [16,17], each relay utilized superposition coding to assist each source. However, the developed upper bound of DMT in [16,17] can only be achieved with some assumptions on the conditions of inter-relay channels. ...
... In [16,17], each relay utilized superposition coding to assist each source. However, the developed upper bound of DMT in [16,17] can only be achieved with some assumptions on the conditions of inter-relay channels. The work in [18] considered a more general scenario and proposed a cooperative protocol, called relay-assisted CMA (R-CMA), which carefully schedules the multiple sources and relays' transmission, but the optimal MISO bound can only be approached for a large number of relays. ...
... It is not difficult to obtain the PDF of z as where C q p = p! (p−q)!q! , p and q are positive integers, and p ≥ q. Splitting each term on the right side, Equation (A. 16) can be calculated as . ...
In this paper, a novel spectrally efficient half-duplex cooperative transmission protocol is proposed for cooperative multiple-access channels in wireless vehicular networks, where multiple sources (vehicles) deliver messages to a common destination (roadside base station or roadside infrastructure) with the help of multiple decode-and-forward relays (roadside stations). The basic idea is to apply superposition coding at each transmitter in order to achieve the full diversity gain, where the linear zero-forcing detection is used at each relay to combat inter-relay interference. Compared to existing uplink cooperative protocols, the proposed scheme can exploit the cooperation involving both the relays and the sources. An achievable diversity-multiplexing trade-off is developed for the proposed transmission protocol. Even with strong inter-relay interference which has been ignored by many existing works, the proposed scheme can still approach the optimal multiple-input single-output upper bound. Numerical results have also been provided to demonstrate the performance of the proposed protocol.
... Also, in [18] the presence of a direct link offered increased diversity gain and the capacity regions for a successive relaying network were given. In the extension of this work in [19], assuming again that the inter-relay channels are strong, instead of subtracting the interference, IRI is decoded and by employing superposition coding it is forwarded to the destination. In this way, improved diversity-multiplexing tradeoff (DMT) is achieved. ...
In this work, we present a buffer-aided successive opportunistic relaying scheme (herein called BA-SOR) that aims at improving the average capacity of the network when inter-relay interference (IRI) arises between relays that are selected for simultaneous transmission and reception.We propose a relay selection policy that, by exploiting the benefits of buffering at the relays, decouples the receiving relay at the previous time slot to be the transmitting relay at the next slot. Furthermore,
we impose an interference cancellation (IC) threshold allowing the relay that is selected for reception, to decode and subtract the IRI. The proposed relaying scheme selects the relaying pair that maximizes the average capacity of the relay network. Its performance is evaluated through simulations and comparisons with other state-of-the-art half- and full-duplex relay selection schemes, in terms of outage probability, average capacity and average delay. The results reveal that a tradeoff has to be made between improving the outage at the cost of reduced capacity and increased delay and vice versa. Finally, conclusions are drawn and future directions are discussed, including the need for a hybrid scheme incorporating both half and full-duplex characteristics.
... In [6], [7] the capacity region for networks with two relays supporting successive relaying were given in the absence of a source-destination (SD) link and with the availability of a SD link, correspondingly. The work in [8] extended [7] and instead of interference subtraction, IRI was decoded and by employing superposition coding it was forwarded to the destination in a scenario where the interrelay channels are strong. In this way, improved diversitymultiplexing tradeoff (DMT) was achieved. ...
In this work, we present a buffer-aided successive opportunistic relaying (BA-SOR) scheme that aims to improve the average capacity of the network when inter-relay interference (IRI) arises between relays that are selected for transmission and reception. In order to exploit the benefits of buffering at the relays, we propose a relay selection policy that decouples the receiving relay at the previous time slot to be the transmitting relay at the next slot. Furthermore, we impose an interference cancelation (IC) threshold allowing the relay that is selected for reception, to decode and subtract the IRI. The relaying scheme proposed selects the relaying pair that maximizes the average capacity of the relay network. The performance of the proposed scheme is evaluated through simulation and comparisons with other state-of-the-art half and full-duplex relay selection schemes, in terms of outage probability, average capacity and average delay. The results reveal that a tradeoff has to be made between improving the outage on the cost of reduced capacity and increased delay, and vice versa. Finally, conclusions are drawn and future directions are discussed, including the need for a hybrid scheme incorporating both half and full-duplex characteristics.
