基于有效信噪比的自动重传请求协议性能比较

Performance comparison of ARQ based on effective SNR

对自动重传请求协议(ARQ)系统的重传能量进行分析,提出一个新概念——有效信噪比。以有效信噪比为基准,比较了3种校验码对ARQ系统误比特率、重传次数、吞吐量性能的影响。仿真结果表明,ARQ系统的可靠性仅在中高传统信噪比下得到提高。在低传统信噪比下,重传导致ARQ系统实际的有效信噪比远大于无重传系统;在相同有效信噪比下,ARQ系统的误比特率性能劣于无重传系统,此时不应使用ARQ。混合ARQ(HARQ)通过纠错码降低系统重传频率,可有效缓解该问题。

Retransmission energy of automatic repeat request（ARQ） is analyzed and the new concept of effective signal-noise ratio （SNR） is proposed. Based on the effective SNR, the accepted bit error probability （BEP）, number of retransmissions and throughput of ARQ systems with three different channel codes are analyzed and compared. Simulation results show that the BEP is only improved by ARQ at high conventional SNR. At low conventional SNR, ARQ incurs more energy consumption due to retransmissions, resulting in an effective SNR higher than the retransmissionless system; at the same effective SNR, ARQ performs worse than the retransmissionless system. Therefore, ARQ should not be used at low conventional SNR. Using error correction code, hybrid ARQ （HARQ） lowers the number of retransmissions and alleviates this problem.