Joint routing and scheduling in fixed multi-user MIMO wireless multi-hop networks

We study joint routing and scheduling problem in fixed multi-user MIMO (MU-MIMO) multi-hop wireless networks under a physical interference model. The objective is to compare the throughput performance of single user MIMO (SU-MIMO) and MU-MIMO schemes in wireless mesh networks. We propose a MU-MIMO scheme with combined single- and multi-antenna transmission for multi-hop wireless networks. We formulate a cross-layer optimization framework to determine the optimal max-min throughput of the flows and the optimal routing and scheduling configuration of a wireless network with the following schemes: SU-MIMO, MU-MIMO with single antenna transmission, and MU-MIMO with combined single- and multi-antenna transmission. We solve the cross-layer optimization problem exactly for several medium size uplink wireless mesh networks. These numerical results show that: 1) at low transmission power, the MU-MIMO schemes provide a significant throughput gain over the SU-MIMO scheme; 2) the MU-MIMO schemes allow a network to be connected with lower transmission power; 3) at low transmission power, the throughput gain of the MU-MIMO scheme with combined single- and multi-antenna transmission over the MU-MIMO scheme with single antenna transmission is significant and this gain increases with increasing the number of antennas per node; and 4) the throughput gains of the MIMO schemes over a single-input and single-output scheme increase with increasing the transmission power and the number of antennas per node.