Transmission Capacities for Overlaid Wireless Networks with Spatial Multiplexing

In this paper, the authors investigate the performance of open-loop spatial multiplexing in overlaid ad hoc networks. Based on a stochastic geometry model, they derive exact closed-form expressions for the transmission capacity of two coexisting networks (a primary network vs. a secondary network) employing spatial multiplexing with Zero-Forcing (ZF) receivers. Simulation results confirm the accuracy of their expressions. In addition, they discuss the impact of multi-antenna scheme on the transmission capacity of the overlaid networks. Their findings show that the sum transmission capacity of the overlaid networks will improve significantly over that of a single network if a slight outage probability increase is allowable for the primary network.