Relay selection in cooperative networks with frequency selective fading

Abstract

In this article, we consider the diversity-multiplexing tradeoff (DMT) of relay-assisted communication through correlated frequency selective fading channels. Recent results for relays in flat fading channels demonstrate a performance and implementation advantage in using relay selection as opposed to more complicated distributed space-time coding schemes. Motivated by these results, we explore the use of relay selection for the case when all channels have intersymbol interference. In particular, we focus on the performance of relaying strategies when multiple decode-and-forward relays share a single channel orthogonal to the source. We derive the DMT for several relaying strategies: best relay selection, random relay selection, and the case when all decoding relays participate. The best relay selection method selects the relay in the decoding set with the largest sum-squared relay-to-destination channel coefficients. This scheme can achieve the optimal DMT of the system under consideration and generally dominates the other two relaying strategies which do not always exploit the spatial diversity offered by the relays. Different from flat fading, we found special cases when the three relaying strategies have the same DMT. We further present a transceiver design which is proven to asymptotically achieve the optimal DMT. Monte Carlo simulations are presented to corroborate the theoretical analysis and to provide a detailed performance comparison of the three relaying strategies in channels encountered in practice.

An adaptive transmission protocol for exploiting diversity and multiplexing gains in wireless relaying networks

“…With reference to Figure 5, it is observed that the proposed protocol reports an improved BER performance. Specifically, it results in performance gains of 1.3, 2.3 and 3.6 dB over networks employing Alamouti's STBC, 3 4 -OSTBC and ABBA code, respectively. In addition, a gain of 1 dB was achieved over the STBC-SM of [32] because of the unique selection of the c codewords and the use of optimised star-QAM modulation.…”

“…In recent years, the spatial diversity of wireless relaying networks (WRNs) has been used to improve signal quality in wireless transmission [1][2][3][4][5]. A WRN constructs a virtual multiple-input multiple-output (MIMO) system using multiple neighbouring client apparatuses as relaying nodes.…”

Performance Evaluation of Adaptive LDPC Coded Modulation Cooperative Wireless Communication System With Best-Relay Selection

“…The mutual information of the proposed cooperative wireless communication system with combined BRS and AMC is given by [21] …”

A smart scheme for relay selection in cooperative wireless communication systems

“…However, choosing the relay(s) randomly might not be very efficient in terms of gain. For frequency-flat fading channels, it was proven in [7] that in some situations no diversity gain can be obtained if the random selection scheme is used, whereas for frequency-selective channels, it was shown in [21] that only in some cases the random relay selection can achieve the same diversity as the best relay selection.…”

“…Compared to cooperative diversity schemes where all relays transmit their message to the destination concurrently, several recent results have demonstrated the performance and implementation advantages of one or a subset of relays assisting transmissions in a wireless network [10][11][12][13][14][15][16][17][18][19][20][21]. With relay selection, the complexity, synchronization, and overhead of the cooperative system are relaxed, leading to an increase in the spectral efficiency.…”