Date Added: Dec 2011
Multiple Input Multiple Output (MIMO) adds a new dimension to be exploited in Cognitive Radio (CR) by simultaneously serving several users. The spatial domain that is added through MIMO is another system resource that has to be optimized, and shared when possible. In this paper, the authors present a spatial sharing that is carried out through Zero Forcing Beamforming (ZFB). The power consumption in such a scenario is mathematically formulated and compared to single user case, to check the feasibility of employing spatial cognition from the power's perspective. Interesting conclusions are obtained about the utility of spatial cognition, thanks to the derived closed form expressions for the data rate and consumed power.