Quasi-synchronous cooperative networks: a practical cooperative transmission protocol

Abstract

In this article, we propose a cooperative space-time coding (STC) protocol, amalgamating the concepts of asynchronous cooperation, noncoherent detection, as well as distributed turbo coding (DTC), where neither symbol-level time synchronization nor channel-state information (CSI) estimation is required at any of the cooperating nodes, while attaining high performance even at low signal-to-noise ratios (SNRs). More specifically assuming the system configuration of a single source node, multiple relay nodes, and a single destination node, each having a single antenna element (AE)a practical cooperative differential space-time spreading (CDSTS) scheme is designed using interference rejection spreading codes, to eliminate the effect of synchronization errors between the relay nodes without the assistance of channel estimation or equalization. Furthermore, a set of space–time codewords are constructed based on differential linear dispersion codes (DLDCs), which allows our CDSTS system to support an arbitrary number of relay nodes operating at a high transmission rate because of its flexible design. Rather than using conventional single-relay-assisted DTCs, novel multirelay-assisted DTCs and a three-stage iteratively decoded destination receiver structure are developed for attaining a high-transmit diversity order. In our simulations, the system parameters are designed using extrinsic information transfer (EXIT) chart analysis, followed by the characterization of the achievable bit error rate (BER) performance for
various synchronization delay values, as well as for various diversity-multiplexing relationships in frequency-selective fast and/or quasi-static Rayleigh fading environments.

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Identifiers

ORCID for Soon Xin Ng: orcid.org/0000-0002-0930-7194

ORCID for Lajos Hanzo: orcid.org/0000-0002-2636-5214

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