Joint antenna selection and power allocation for distributed-stbc cognitive small cell networks

Small cell networks enhance spectrum efficiency by handling the indoor traffic of mobile networks on a frequency-reuse operation. Because most of the current mobile traffic happens indoor, we introduce a prioritization shift by imposing a limitation on the outage generated by the outdoor mobile system to the indoor small cells. In this paper, we consider downlink spectrum sharing between a system consisting of small cells and a macrocell relay network. The relays constitute a distributed-STBC relaying which provides the data traffic for the outdoor system terminals. We propose a joint transmit antenna selection and power allocation which minimizes the bit error rate of the outdoor mobile terminal. The optimization is constrained by the outage at the small cell located near the cooperating transmit relays. The proposed optimization yields a dynamic selection of the relays pertaining to the outdoor mobile terminal performance. The simulation results show that our proposal exhibits a better bit error rate compared to the conventional Alamouti STBC with equal power allocation.