Improving throughput for downlink multi user MIMO-LTE advanced networks using SINR approximation and hierarchical CSI feedback

In multi user MIMO-LTE advanced networks, the main issue is related to signal to noise ratio SINR mismatch which can result in reduced throughput and performance. Also the conventional code books may result in feedback overhead when the channels change slowly. Hence in this paper, we propose downlink multi user MIMO-LTE advanced networks using SINR approximation and hierarchical CSI feedback. Initially, signal and spatially correlated flat fading channels model of MU-MIMO is defined. Then a signal to noise ratio SINR approximation techniques is employed which utilises the channel state information at the base station. An advance structural codebook and an idea of hierarchical feedback are introduced. The main idea of hierarchical feedback is that if the channel is altered slowly, the channel state information feedback can be aggregated over multiple feedback intervals so that the aggregated bits index a larger codebook. There are pre-defined numbers of levels in a hierarchical codebook tree. This increased codebook size can effectively improve the performance of MU-MIMO. By simulation results, we show that the proposed technique improves the throughput and reduces the overhead.