A transmit antenna selection diversity scheme based on ACK/NACK feedback

In this paper, we present a new transmit diversity scheme which uses the hybrid automatic repeat request (HARQ) feedback message ACK/NACK as the antenna selection indicator. The proposed scheme is simpler than the conventional selective transmit diversity (STD) plus HARQ scheme or the Alamouti's space-time block coding (STBC) plus HARQ scheme. For the Chase combining HARQ and two-branch diversity, we have derived the closed form expression of the outage rate and the throughput for the STBC/HARQ, STD/HARQ and the proposed scheme under static flat Rayleigh fading channel. The results show that the three diversity systems have the same diversity order. The STD/HARQ scheme requires the most feedback load and has the best performance. STBC/HARQ and the proposed scheme have the same feedback load and the same outage rate while the proposed scheme has better throughput performance which is close to STD/HARQ.