Caleb K. Lo, Sriram Vishwanath, Robert W. Heath · 2013
This paper considers the problem of selecting a subset of nodes in a two-hop wireless network to act as relays in aiding the communication between the source-destination pair. Optimal relay subset selection with the objective of maximizing the overall throughput is a difficult problem that depends on multiple factors including node locations, queue lengths and power consumption. A partial decode-and-forward strategy is applied in this paper to improve the tractability of the relay selection problem and performance of the overall network. Note that the number of relays selected ultimately determines the performance of the network. This paper benchmarks this performance by determining the net diversity achieved using the relays selected and the partial decode-and-forward strategy. This framework is subsequently used to further transform relay selection into a simpler relay placement problem, and two proximity-based approximation algorithms are developed to determine the appropriate set of relays to be selected in the network. Other selection strategies such as random relay selection and a greedy algorithm that relies on channel state information are also presented. This paper concludes by showing that the proposed proximity-based relay selection strategies yield near-optimal expected rates for a small number of selected relays.
Cited by 0
Sung Hoon Lim, Kwang Taik Kim, Young-Han Kim · 2014
A new coding scheme for broadcasting multiple messages over a general relay network is presented. The proposed distributed decode-forward scheme combines Marton coding for single-hop broadcast channels and partial decode-forward for relay channels by Cover and El Gamal. For the N-node Gaussian broadcast relay network, the scheme achieves within 0.5N bits from the capacity region, extending and refining a recent result by Kannan, Raja, and Viswanath. The main idea of the scheme is to precode all the codewords initially at the source and to decode and forward parts of them on the fly at the relays.
Cited by 7
Sung Hoon Lim, Kwang Taik Kim, Young-Han Kim · arXiv (Cornell University) · 2015
A new coding scheme for general N-node relay networks is presented for unicast, multicast, and broadcast. The proposed distributed decode-forward scheme combines and generalizes Marton coding for single-hop broadcast channels and the Cover-El Gamal partial decode-forward coding scheme for 3-node relay channels. The key idea of the scheme is to precode all the codewords of the entire network at the source by multicoding over multiple blocks. This encoding step allows these codewords to carry partial information of the messages implicitly without complicated rate splitting and routing. This partial information is then recovered at the relay nodes and forwarded further. For N-node Gaussian unicast, multicast, and broadcast relay networks, the scheme achieves within 0.5N bits from the cutset bound and thus from the capacity (region), regardless of the network topology, channel gains, or power constraints. Roughly speaking, distributed decode-forward is dual to noisy network coding, which generalized compress-forward to unicast, multicast, and multiple access relay networks.
Cited by 4Open access
Yiyong Chin, Anushka Widanagamage, Dhammika Jayalath · 2013
In this paper, we propose a novel slotted hybrid cooperative protocol named the sequential slotted amplify-decode-and-forward (SADF) protocol and evaluate its performance in terms of diversity-multiplexing trade-off (DMT). The relays between the source and destination are divided into two different groups and each relay either amplifies or decodes the received signal. We first compute the optimal DMT of the proposed protocol with the assumption of perfect decoding at the DF relays. We then derive the DMT closed-form expression of the proposed sequential-SADF and obtain the proximity gain bound for achieving the optimal DMT. With the proximity gain bound, we then found the distance ratio to achieve the optimal DMT performance. Simulation result shows that the proposed protocol with high proximity gain outperforms other cooperative communication protocols in high SNR regime.
Cited by 2
Tang, Yao · eScholarship@McGill (McGill) · 2014
Cooperative transmission acts as a distributed solution for providing robust wireless communications.It pools available resources, such as power and bandwidth, across the network.The relay network is the simplest information theoretic model for a cooperative wireless network and a full understanding of communication limits over such a network can potentially shed light on the design of more efficient wireless networks.However, the capacity of the relay network is still unknown.As a step towards the goal of calculating the capacity, we derive the capacity bounds for a single-source single-destination relay network based on partial decode-forward.In the first part of the thesis, we review existing bounds on the capacity of the discrete memoryless relay channel.We also review decode-forward and partial decode-forward in the relay network.In the second part of the thesis, we first introduce a discrete memoryless relay network model consisting of one source, one destination and N relays.We then design a scheme based on partial decode-forward relaying.The source splits its message into one common part and N +1 private parts which are to be decoded at different relays.The source encodes split message parts using length-N block Markov coding, in which each private message part is independently superimposed on the common parts of the current and N previous blocks.Using joint sliding window decoding, each relay fully recovers the common message part and its intended private message part with the same block index, then forwards them together to the following nodes in the next block.We derive the achievable rate of this scheme in a compact form.The result is a generalization of and can be particularized to a known decode-forward lower bound for an N -relay network and partial decode-forward lower bound for a two-relay network.We then apply our proposed scheme to a Gaussian relay network and obtain its capacity lower bound considering power constraints at transmitting nodes.In the third part of the thesis, we introduce the concept of exhaustive message splitting for partial decode-forward in a single-source single-destination relay network with N relays, in which the relays are divided into subsets, and each different relay subset has a distinct private message part to decode.We study this scheme in more depth in a three-relay network based on block Markov encoding.We derive its achievable rate.Finally, we apply this scheme to a Gaussian three-relay network and show that our scheme generalizes network decode-forward and the private message splitting scheme as shown in the second ii part.iii Abrg La transmission cooprative agit comme tant une solution diffuse, permettant de fournir une communication sans fil trs robuste.Elle regroupe les ressources disponibles, comme la puissance et la bande passante, travers le rseau.Le rseau relais est le modle thorique le plus simple pour un rseau sans fil coopratif et la comprhension des limites de communication travers de ce rseau permet potentiellement de saisir la conception d'un rseau sans fil plus efficace.Par contre, la capacit du rseau relais est encore inconnue.Dans cette thse, nous adressons la conception du schma du decode-forward partiel dans un rseau relais ayant une source et une destination unique.Dans la premire partie de cette thse, nous rvisons le rseau relais.Nous rvisons aussi le decode-forward ainsi que le decode-forward partiel dans les rseaux relais.Dans la deuxime partie de cette thse, nous introduisons un rseau relais sans mmoire compos d'une source, d'une destination et de relais N .Par la suite, nous concevons un schma partir du rseau decode-forward partiel.La source divise son message en une partie commune et en parties prives N + 1 qui sont destines des relais diffe length-N black Markov, dans lequel chaque partie du message priv est superpos indpendamment sur les parties communes du bloc actuel et des blocs prcdents N .En utilisant le dcodage conjoint fentre coulissante, chaque relais rcupre la partie du message commune et sa partie du message priv ayant le mme index bloc, et les envoi par la suite ensemble aux noeuds du bloc suivant.Nous drivons son taux ralisable dans un format compact.Le rsultat permet de rduire la borne infrieure connue du decode-forward d'un rseau N -relais et la borne infrieure du decode-forward partiel pour un rseau deux relais.Nous appliquons par la suite notre schma propositionnel un rseau relais gaussien et d'obtenir sa capacit de borne infrieure en prenant en compte les contraints de puissance aux noeuds metteurs.Dans la troisime partie de cette thse, nous introduisons le fractionnement exhaustif des messages pour le decode-forward partiel ayant une source et une destination unique dans un rseau relais ayant N relais, dans lequel chaque sous-ensemble diffrent du relais contient un message priv distinct dcoder.Nous tudions profondment ce schma dans un rseau trois relais bas sur le codage un bloc Markov.Nous drivons son taux ralisable.Nous fournissons un graphique orient qui dtaille le superpositionnement de la structure du codebook afin d'aider le lecteur comprendre la hirarchie de la gnration du codeword.3.
Cited by 0Open access
Hina Ajmal (4803999), Aimal Khan (4372159), Saad Rehman (4803996) et al. · Figshare · 2018
<p>Outage probability vs. the pseudo SNR for amplify-and-forward, decode-and-forward, and adaptive amplify-or-decode & forward.</p>
Cited by 0Open access
Rooholah Aghajani, Reza Saadat, Mohammad Reza Aref · SHILAP Revista de lepidopterología · 2015
In this paper, the symbol error rate of M-PSK modulation in managed relay scheme is computed. In the conventional technique, the relay always decodes the received signal and re-sends it to the destination. In the destination, the two copies of the signal will be combining in MRC manner. In another method, the relay will partially participate in the signal transmission. In this way, If the destination is not able to decode the source signal properly then requests the relay to re-send signal. Therefore, the average power consumption of the system can be reduced. In this paper, the M-PSK modulation error rate in Rayleigh channels is accurately obtained. Then, an approximation of the symbol error rate in the medium and high signal to noise ratio is achieved. Based on this approximation the power allocation coefficient is derived. The symbol error rates of two schemes are compared. Finally, it is showed that in the equal average power consumption, the symbol error rate of the managed scheme is lower than other scheme.
Cited by 0Open access
Sung Hoon Lim, Kwang Taik Kim, Young-han Kim · 2014
Abstract—A new coding scheme for broadcasting multi-ple messages over a general relay network is presented. The proposed distributed decode–forward scheme com-bines Marton coding for single-hop broadcast channels and partial decode–forward for relay channels by Cover and El Gamal. For the N-node Gaussian broadcast relay network, the scheme achieves within 0.5N bits from the capacity region, extending and refining a recent result by Kannan, Raja, and Viswanath. The main idea of the scheme is to precode all the codewords initially at the source and to decode and forward parts of them on the fly at the relays. I.
Cited by 0
H.H. Sneesens · 2005
Mobile receivers can benefit from an increased spatial diversity through cooperation. Two relaying techniques are typically used: either amplify and forward (AF) or decode and forward (DF). This contribution presents a new technique, which combines the main advantages of both AF and DF. This technique amounts to a DF scheme where all operations are performed in a soft-input soft-output fashion. The relay performs a soft decoding of the received signal and reencodes it softly, that is incorporates reliability information about the decoded data. Simulations show that this Soft-DF scheme outperforms both AF and DF.
Cited by 54
Xianyi Rui · International Journal of Communication Systems · 2010
Abstract Exact expressions for outage probability and symbol error rate are presented for a decode‐and‐forward cooperative network with partial relay selection. An independent but not identically distributed Nakagami‐ m fading environment is considered. Numerical and simulated results show the validity of the analytical results. Copyright © 2010 John Wiley & Sons, Ltd.
Cited by 23
Chao Wang, Yijia Fan, Ioannis Krikidis et al. · 2008
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 concurrent DF relaying, in which the advantage of the inter-relay interference is not fully extracted.
Cited by 14
Vighnesh S Bhat, A. Chockalingam · 2023
Orthogonal time frequency space (OTFS) modulation and index modulation (IM) are promising techniques in wireless communications. OTFS excels in high mobility scenarios by using information signaling in the delay-Doppler domain, while IM offers improved spectral efficiencies and bit error performance. In this study, we analyze the performance of OTFS with IM (OTFS-IM) in a decode-and-forward (DaF) relay communication system. The communication involves two hops between the transmitter, receiver nodes through a relay node. We derive a closed-form expression for the end-to-end pairwise error probability in OTFS-IM with DaF relaying and assess the achieved asymptotic diversity order. Our simulation results show that i) the use of indexing improves the performance of OTFS with DaF relaying ii) the simulated upper bound on the bit error rate (BER) validates the analytically predicted diversity orders.
Cited by 5
Wei Zhang · Journal of computer and electronics studies · 2019
For cooperative system, in which eavesdropper can be anywhere, so it may overhear information through both source and relay’ transmission . In this letter, we evaluate the secrecy performance of decode-and- forward (DF) system with both the optimal relay selection (ORS) and the conventional relay selection (CRS) schemes, and the closed expression on the secrecy outage probability(SOP) of two schemes are derived; The derivations are confirmed through Monte Carlo simulations.
Cited by 0Open access
Georgy Levin, Sergey Loyka · Repository for Publications and Research Data (ETH Zurich) · 2012
Performance of multi-hop MIMO relay channels under the amplify-and-forward and decode-and-forward protocols are compared via the capacity and SNR gains.In an Nhop channel of linear topology with multi-antenna source and destination and single-antenna relay nodes, the capacity gain of the DF relaying over the AF one does not exceed log 2 N bit/s/Hz and its SNR gain does not exceed N , for any channel realization.This conclusion also applies to selection relaying, to the outage probability/capacity and the ergodic capacity in an arbitrary block-fading channel, and can be further extended to hybrid relaying.The conditions under which the DF and AF relaying have nearly identical performance are identified.
Cited by 42Open access
Namshik Kim, John R. Barry · 2012
We consider the problem of combining the signals received from a decode-and-forward relay with those received from the source. As an alternative to the high-complexity maximum-likelihood combining strategy, we propose a bit-wise combining strategy in which the received signals are first converted to log-likelihood values before being combined. We show that, subject to the bit-wise constraint, the optimal combining strategy for binary alphabets - minimizing the probability of error - applies a sigmoidal nonlinearity to the relay log-likelihood values before adding to the source log-likelihood values. Unlike the maximal-ratio combining strategy, which has no diversity for the Rayleigh-fading decode-and-forward relay channel, the proposed strategy exhibits the maximum diversity order of two.
Cited by 0
Mingkwan Somphruek, Rolando Carrasco, Stéphane Le Goff · 2010
As fading due to multipath propagation is an important issue in wireless systems, diversity techniques are employed in order to reduce the multipath fading effect. Cooperative communication represents a new class of diversity schemes in which multiple nodes equipped with a single antenna cooperate to generate a virtual multiple-antenna transmission system and thus offer the benefits of spatial diversity. This paper investigates the performance of the well known decode-and-forward cooperative technique on the flat fading indoor channel and also on the pedestrian and vehicular frequency-selective fading channels with decision feedback equalisation, which model the physical layer of UMTS networks in different environments. The performance is evaluated in terms of bit error rate as a function of signal-to-noise ratio with simulation results showing that decode-and-forward relaying provides a remarkable performance improvement over direct transmission.
Cited by 0
Stefano Savazzi, Umberto Spagnolini · IEEE Transactions on Information Theory · 2008
<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Cooperative transmission protocols over fading channels are based on a number of relaying nodes to form virtual multi-antenna transmissions. Diversity provided by these techniques has been widely analyzed for the Rayleigh fading case. However, short range or fixed wireless communications often experience propagation environments where the fading envelope distribution is meaningfully different from Rayleigh. The main focus in this paper is to investigate the impact of fading distribution on performances of collaborative communication. Cooperative protocols are compared to co-located multi-antenna systems by introducing the concept of cooperative fading region. This is the collection of fading distributions for which relayed transmission can be regarded as a competitive option (in terms of performances) compared to multi-antenna direct (noncooperative) transmission. The analysis is dealt with by adopting the information theoretic outage probability as the performance metric. Cooperative link performances at high SNR are conveniently expressed here in terms of diversity and coding gain as outage parameters that are provided by the fading statistics of the channels involved in collaborative transmission. Advantages of cooperative transmission compared to multi-antenna are related to the propagation environment so that the analysis can be used in network design. </para>
Cited by 28
Zhihang Yi, Il‐Min Kim · IEEE Vehicular Technology Conference · 2007
In this paper, we focus on the decode-and-forward (DF) cooperative networks with relay selection. Many detection schemes have been proposed for the DF; but it has been shown that the cooperative maximum ratio combining (C-MRC) can achieve almost the same performance as the optimum maximum likelihood detector and has a much lower complexity. Therefore, we first combine the C-MRC with the relay selection and show that it achieves the full diversity order by deriving an upper bound of its average bit error rate (BER). In order to reduce the signaling overhead in the C-MRC with relay selection, a novel detection scheme, namely product MRC (P-MRC), is proposed for the DF and it achieves the same diversity order as the C-MRC. Then we combine the P-MRC with the relay selection and show that it achieves the full diversity order by deriving an upper bound of its average BER.
Cited by 18
Neha Jain, Vivek Ashok Bohara, Anubha Gupta · 2016
The theory of compressive sensing (CS) is acquiring attraction now a days, as it can reconstruct a sparse signal at a sub-Nyquist sampling rate. Recently CS is being used in communication systems for channel estimation, Massive MIMO, cognitive radio etc. In this paper, CS is using in an overlay cooperative spectrum sharing scheme for decode and forward relay, to not only overcome the drawbacks of CSS but also to enhance the performance of the system in terms of achievable rate.
Cited by 0
Lisa Pinals, Ahmad Abu Al Haija, Mai Vu · 2016
In this paper, we examine message prioritization in terms of both rate and reliability in the two-way relay channel using decode-forward relaying. Each source sends both a low priority message and a high priority message. We design a scheme that routes the high priority messages through the relay and direct link but the low priority message is only decoded by the destination. For fixed message priorities, the rate-optimal power allocation is analytically determined based on the link state. The high priority message is guaranteed to have greater reliability than that of the low priority message. We analytically formulate this outage probability from both the perspective of a single user and that of the overall system, and numerically examine the increased reliability for the high priority message.
Cited by 2