Throughput based transmit antenna selection for underlay CR MIMO systems

Cognitive Radio (CR) is a promising technology for improving spectrum utilization. When combined with multiple input multiple output (MIMO) technology, which achieves high spectral efficiency, CR MIMO can serve as a solution to the ever increasing demand for spectrum. Antenna selection is a signal processing technique that improves the performance of MIMO systems and reduces their hardware complexity and cost. Throughput based antenna selection utilizes cross layer information to select the subset of antennas that maximizes system throughput, resulting in improved overall system performance. In this paper we propose transmit antenna selection that maximizes the throughput of underlay CR MIMO systems subject to interference constraints at the primary user (PU) receiver(s). Performance is further improved by integrating adaptive modulation into the scheme to simultaneously select the antenna(s) and modulation scheme that optimizes the performance. Numerical results show that the proposed scheme has superior performance compared to conventional antenna selection which maximizes capacity.