Data aware user selection in cognitive downlink MISO precoding systems

This paper tackles the problem of data aware user selection in cognitive downlink MISO precoding. The new scheme is based on utilizing the data and channel information to select the cognitive users that minimize the transmit power at the cognitive base station (CBS). The role of data exploitation in user selection is discussed by classifying the interference into two types: destructive and constructive. Selecting a set of users whose simultaneous transmissions interact constructively from interference perspective is proposed in this paper. Therefore, the interference can be viewed as an additional source of desired energy that should be exploited. Optimal solutions for this problem can be prohibitively complex for online implementation at the base station. A novel suboptimal user selection scheme based on the joint utilization of channel and data information is proposed. To evaluate the performance of the proposed technique, intensive computer simulations are performed to compare it with conventional techniques.