Performance Analysis of OFDM-Based Decode-and-Forward Relay Network with Multiple Interferers over Rayleigh Fading Channels

Relay communications, as a promising technique to help in attaining broader coverage and combating the impairments of the wireless channel, have gained significant interests at the beginning of this century [1–3]. Recently, various cooperation protocols, for example, amplify-and-forward (AF) and decode-and-forward (DF) [2], have been proposed for cooperative wireless networks. Subsequently, the performance analysis of the relay network has attracted a lot of interest, considering different issues, such as cooperation protocols [4], channel models [5], power allocation schemes [6], and so on. Due to aggressive reusing of frequency channels for highspectrum utilization, the cochannel interference (CCI) is unavoidable in the cellular system. By now, many excellent works have investigated the performance of the traditional point-to-point wireless system in the presence of CCI [7–9]. However, in the relay network, the CCI also appears, due to reusing the same frequency channel for both the competing users and the relays. In [10], the authors examine the feasibility of applying collaborative relays to the large-scale wireless network for the throughput improvement by modeling the interference-sensitive region. In [11], the authors consider a time-division multiple-access (TDMA) system in which a single time slot is shared by many relays and employ dual-hop relays to improve its throughput. Based on the model in [11], the authors in [12] consider the case where the destination is corrupted by a number of CCIs, while the relay is only perturbed by an additive white Gaussian noise (AWGN) and obtain the closed-form expression of the outage probability for the dual-hop relay system. It should be pointed out that all the aforementioned papers are confined to the single relay, the flat-fading channel, or the special case in which the interference only affects the destination node. In practice, most wireless transmissions experience the scattered and delayed propagation paths, which result in the so-called frequency-selective fading channels. For multiple relays and frequency-selective fading channels, more should be considered involving the selection of the relays, the combiner for combatingmultiple interferers at the relays and the destination, and so on. For frequency-selective channels, the orthogonal frequency division multiplexing (OFDM) is often employed in practice. Hence, many works which have been provided are focusing on OFDM-based relay networks [13–15]. It remains an open problem to determine the performance of OFDM-based relay networks over frequency-selective fading channels. The performance of OFDM-based relay networks is a significative work for the system design.