Abstract
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.
Highlights
Cooperative communications can increase achievable rates and decrease susceptibility to channel variations [1,2,3] and have potential practical applications in cellular systems, wireless ad hoc, and sensor networks
Distributed turbo codes can be extended to networks with different number of relays using multiple turbo codes [16], the overall code rate decreases with the increase of relay number [11]
In order to reduce the decoding complexity and adapt well to the channel variations, a progressive decoding strategy is proposed for relay nodes as illustrated in Figure 3 using the partial error detecting and correcting capabilities of the generalized low-density (GLD) code
Summary
Cooperative communications can increase achievable rates and decrease susceptibility to channel variations [1,2,3] and have potential practical applications in cellular systems, wireless ad hoc, and sensor networks. Most of the cooperative strategies above are devised for the classical three-node relay channel model, that is, the network with only one relay. In wireless relay networks, the number of relays participating in cooperation may vary from time to time due to the random mobility of nodes [15]. Distributed turbo codes can be extended to networks with different number of relays using multiple turbo codes [16], the overall code rate decreases with the increase of relay number [11]. In this paper, based on the DF relay protocol, a novel coding scheme is proposed for cooperative relay networks using generalized low-density (GLD) codes [17,18,19], which has a fixed overall code rate.
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