A Practical Scheme to Achieve Sum Capacity for Strong Interference-limited Scenarios

Cell-edge users suffer from harsh interference due to cell range expansion in a heterogeneous network. An information theoretic approach, namely the joint decoding, can in principle achieve the sum-capacity, but practical implementation remains a challenge. For example, a rate splitting (RS) scheme is an optimal alterative for multiple access channels, but it is not optimal for interference channels. This motivates us to develop a new technique. In this paper, a practical scheme called multi-layer rate splitting (MLRS) is introduced. We prove that this MLRS scheme can achieve the sum capacity when the interference channel satisfies certain conditions. Moreover, a power allocation algorithm is proposed to find the optimal power splitting ratios for the MLRS scheme. Simulation results show that the MLRS scheme is an effective alternative to exploit the benefit of the joint decoding for interference channels.