Threshold decision for rank adaptation based on cumulative channel capacity

Abstract

The channel capacity is improved by MIMO (Multiple Input Multiple Output) increasing the number of transmit and receive antennas. However, it is difficult for a receiver to decode symbols when the rank of a MIMO channel is less than the number of transmitted antennas. Thus, rank adaptation has been proposed to control the number of transmitted streams in accordance with propagation environments. Conventional rank adaptation degrades the performance of controlling the number of streams in an unanticipated channel environment. Therefore, we proposed the rank adaptation using cumulative channel capacity. Although the rank adaptation has potential to improve the channel capacity, the performance depends on the threshold, which is used to change the number of streams. Therefore, threshold decision, which is robust to varying channel environments, is introduced into the rank adaptation based on cumulative channel capacity in this paper.