On the spectral efficiency of MIMO two-way multihop networks with co-existing flows

In this paper, we investigate the spectral efficiency of MIMO two-way multihop networks when multiple flows co-exist and share the same channel. We assume that each multihop flow mitigates only its own intra-flow interference. More precisely, spatial array processing cancels adjacent node interference and a jointly optimal routing and power allocation strategy mitigates the weaker interference from far nodes. By assuming two types of topology, we study the effect of the inter-flow interference on the end-to-end capacity when the density of flows increases. For the linear topology, we show that multihop routing significantly improved the overall spectral efficiency in dense multihop networks; while single hop MIMO performed better at high SNR regime when there is no interfering flow nearby. However, the network was vulnerable to inter-flow interference in the parallel topology. Consequently, distributed admission control and resource allocation schemes, with coordination among the flows, will be of interest to further improve the spectral efficiency of the multihop networks.