HARQ with Chase-combining (HARQ-CC) for Uplink Transmission in Large-Antenna-Array Multicell Systems

摘要

We consider Hybrid Automatic Repeat & reQuest with Chase-combining (HARQ-CC) for uplink spectral efficiency enhancement in a multicell system with base-stations (BSs) using large antenna arrays. Each BS uses a zero-forcing receiver and knows only the channel gains of users in its own cell. We first derive the outage probability and long-term average transmission rate (LATR) of the proposed HARQ-CC while limiting the number of retransmissions. We then formulate the optimal rate-selection problem for the proposed scheme and provide a method to find a solution. Since the optimal-rate selection method for the HARQ-CC scheme is computationally intensive, we develop a sub-optimal rate-selection technique that has a LATR performance close to that of the optimal method. Illustrative results show that the HARQ-CC requires less number of antennas than the non-HARQ scheme to achieve the same LATR performance.