Soft HARQ for 5G Downlink

In this paper, we propose two multi-bit feedback methods for hybrid automatic repeat request (HARQ). Both methods take into consideration of the coding gain of the forward error-correction codes. One method only considers the coding gain of the first transmission, which is named accumulated power (ACP) method. The other method considers the coding gain of both the first transmission and retransmissions, which is named accumulated error-correction performance (ACEP). Simulation results show that both methods achieve higher spectral efficiency and lower latency comparing with existed methods.