On the design of frequency-switching patterns for distributed data fusion over relay networks

Recent contributions have shown that, by switching frequency bands at intermediate relay nodes, enhanced diversity can be attained in two-user wireless frequency division relay networks at a minimum computational cost. This paper elaborates on the design of frequency-switching patterns for more involved relay scenarios. We conclude that in general, the optimum set of frequency-switching patterns is based on the subset of derangement permutations of {f₁,...,f_N}, i.e. of the N frequency bands utilized in the setup. In order to illustrate our approach, our work focuses on the particular distributed data fusion scenario where the data generated by an information source is simultaneously sensed by N nodes and broadcasted, through a relay network, to N remote destinations. Simulation results made for several scenarios verify that the proposed derangement-based relaying scheme outperforms other frequency-switching relay approaches in terms of end-to-end fused Bit Error Rate (BER).