Limiting throughput of MIMO ad hoc networks [MANET example]

We study the throughput limits of a MIMO (multiple-input multiple output) ad hoc network with K simultaneous communicating transceiver pairs. Assume that each transmitter is equipped with t antennas and the receivers with r antennas, we show that in the absence of channel state information (CSI) at the transmitters, the asymptotic network throughput is limited by r nats/s/Hz as K→∞. With CSI corresponding to the desired receiver available at the transmitter, we demonstrate that an asymptotic throughput of t+r+2√tr nats/s/Hz can be achieved using a simple beamforming approach. Further, we show that the asymptotically optimal transmission scheme with CSI amounts to a single-user waterfilling for a properly scaled channel.