On the rate regions for wireless MIMO ad hoc networks

In this paper, the rate regions are studied for MIMO ad hoc networks. We first apply a framework developed for single antenna systems to MIMO systems, which gives the ultimate capacity region. Motivated by the fact that the ultimate capacity regions allow an optimization that may he unrealistic in some networks, a new concept of average rate region is proposed. We show the large gap between the ultimate capacity region and the new average rate region, while the latter is an upper bound on the performance of many existing ad hoc routing protocols. On the other hand, the average rate region also gives the average system performance over fading or random node positions. The outage capacity region is also defined. Through the study of the different rate regions, we show that the gain from multiple antennas for networks is similar to that for point-to-point communications. The gains obtained from multi-hop routing and spatial reuse are also shown for MIMO networks.