Multiple-Source Cooperation: From Code-Division Multiplexing to Variable-Rate Network Coding

Multiple-source cooperation techniques, including conventional code-division multiplexing (CDM) and classic network coding (CNC), are investigated. We adopt a soft sum - product decoding algorithm for the CNC technique to efficiently process a large number of information streams and propose a flexible variable-rate network coding (VNC) technique, which is capable of attaining a near-optimum performance. Quantitatively, the proposed VNC method is capable of operating within 1 dB from the outage capacity of the quasi-static Rayleigh fading channel. The iterative decoding convergence of the multiple-source computation methods is analyzed with the aid of extrinsic information transfer charts.