Cooperative Turbo-Coded Diversity

Cooperative diversity methods have recently been advocated for ad hoc sensor networks, and for other mobile wireless applications as well, as a means of providing diversity against link fading, and thereby offering lower power operation, or better system coverage. Sendonaris et al [1] proposed the concept of cooperative diversity, also known as distributed space-time transmission, and subsequent work by Janani et al [2], Laneman et al [3], and Zhao and Valenti [4], among others, has further developed the protocols and performance for small clusters of cooperating users, normally assuming Rayleigh fading path gains. In this paper, we propose a simple repetition turbo cooperative diversity method for two cooperating nodes, and show its frame error probability (on 640-bit messages) is within 1 dB of the outage probability at the same rate on the quasi-static Rayleigh channel model. To date, this scheme performs as well as a more general (non-repetition) turbo approach, with lower complexity, though information theory allows a gain of about 0.5 dB when repetition is avoided.