Performance of MIMO cross-layer MAC protocol based on antenna selection in ad hoc networks

In this paper, we investigate the performance of a cross-layer (physical and MAC) design for multiple-input multiple-output (MIMO) system that aims at maximizing the throughput of ad hoc networks by selecting the optimum antenna combination. Employing this cross-layer design is shown to improve the overall network performance relative to the case where no antenna selection (AS) is used. To solve the node blocking problem associated with the IEEE 802.11 medium-access control (MAC) protocol, the proposed protocol leverage the available degrees of freedom offered by the MIMO system to allow neighboring nodes to simultaneously communicate using the zero-forcing (ZF) Bell-labs layered space-time (BLAST) architecture. Using the cross-layer design, neighboring nodes share their optimum antenna selection (AS) information through control messages. Given this shared information, nodes set their decisions on the number of selected antennas based on the available spatial channels that guarantees collision-free transmissions. At the destination node, the ZF receiver is employed to extract the desired user data while treating the data from neighboring users as interference. The performance of the proposed cross-layer design is examined through simulations, where we show that the network throughput is significantly improved compared to conventional MAC protocols. Copyright (c) 2010 John Wiley & Sons, Ltd.