Iterative Detection Assisted Cooperative Vehicular Ad Hoc Networking Using Differential Linear Dispersion Coding

In this paper, we propose a Differential Linear Dispersion Coded (DLDC) cooperative transmission scheme suitable for Vehicular Ad Hoc NETworks (VANETs), which facilitates striking a flexible diversity-multiplexing gain tradeoff without requiring channel estimation both at the cooperating nodes and at the destination node. More specifically, DLDC encoding is employed by the source transmitter for broadcasting the source information to the relays, while an LDC-based amplify-and-forward relaying scheme is used at the relays. The proposed technique allows each relay to decide, whether it joins the cooperating cluster without any negotiations with the other nodes. The destination´s receiver detects the DLDC-encoded symbols using a low-complex detection algorithm, rather than an exhaustive Maximum Likelihood (ML) search. Based on the serial-concatenated turbo coding principle, the source node is constituted by the outer channel encoder, a Unity Rate Convolutional (URC) encoder and the DLDC-based mapper. The destination´s receiver iteratively decodes the received signals, exchanging soft information between the DLDC demapper, the URC decoder and the channel decoder. We demonstrate that the proposed cooperative scheme attained a BER of 10 5 within 2.8 dB of the capacity-dependent maximum achievable rate and significantly outperformed the classic MIMOs suffering from the correlated shadow fading of the co-located elements imposed by large-bodied vehicles. We also investigate the effect of different source-relay channels, including perfect, Additive White Gaussian Noise (AWGN), Rician and Rayleigh channels. We conclude by demonstrating that the introduction of an appropriate source-relay SNR threshold for deciding as to whether to actively engage in cooperation improves the achievable performance.