Impact of Delayed Limited Feedback on the Sum-Rate of Intercell Interference Nulling

Users in a multicell cooperative system can feedback channel state information (CSI) of desired and interfering channels to the base station(s) using finite-bandwidth links to manage co-channel interference. Hence, the available feedback resources need to be partitioned efficiently between the multiple channels. In this paper, a feedback-bit allocation strategy is proposed for intercell interference nulling. The approach takes into account the received signal strengths and delays in the feedback and backhaul links. Closed-form expressions for bit partitions are derived, to allocate more bits to quantize the strong interferers with small delays and assign fewer bits to weak channels with large delays. Simulations show how the proposed algorithm yields higher sum-rates than equal bit allocation.