Symbol-level combining for hybrid ARQ on interference-aware successive decoding

This paper proposes a symbol-level combining (SLC) scheme for hybrid automatic-repeat-request (HARQ), being used with an interference-aware successive decoding (IASD) algorithm [1]. Recently, it is revealed that the capacity in an interference channel over point-to-point codes can be achieved by combining two schemes: one is jointly decoding an interfering signal with a serving signal and the other is treating it as noise. Due to its high computational complexity, joint decoding can be practically replaced with successive decoding as suggested in [1]. However, when HARQ is enabled, it has been not well defined how interference should be handled at each transmission. Since interference is changed at each transmission, it is not helpful to store the information of interfering signals. Instead, the proposed scheme employes the decoded information of interfering signals in order to convert an interference channel to a point-to-point channel. The proposed scheme only requires a fixed size of memory and does not increase the detector complexity of IASD with respect to the number of retransmission. Simulation results demonstrate the superiority of the proposed scheme to the optimal SLC scheme at the conventional receiver.