Error propagation analysis for underwater cooperative multi-hop communications

The potential gains of cooperative communication and multi-hopping in underwater acoustic communication channels is examined. In particular, performance of such systems is compared to a comparable single hop system (direct transmission) with a common transmission distance. The effects of error propagation with decode and forward at each relay are explicitly treated and it is shown that strong gains can be achieved by multi-hopping (an effective SNR gain) as well as cooperation, which contributes to a diversity gain. We observe that cooperative diversity gains are retained even when considering error propagation. The analysis is done via a Markov chain analysis for both regular linear and grid networks. Our initial analysis is for single path channels; the effects of inter-symbol interference as well as multi-user interference are examined. It is found that due to the strong decay of signal power as a function of transmission distance, multi-user interference is not as significant as inter-symbol interference. In both cases, cooperative and multi-hopping gains are observed.