基于RCPT码的分块传输新型HARQ系统

A New and Better RCPT HARQ System

在深入研究Ⅱ型、Ⅲ型反馈重传方式和RCPT码的基础上,提出了新型HARQ数据传输系统并为其设计了新型交织器,使编译码时间大幅度缩短。新型HARQ将F个相同的分块穿孔后同时发送;在接收端,将解穿孔后相同的分块进行分集合并。通过理论分析和仿真的结果证明新系统具有Ⅱ型和Ⅲ型HARQ的优点:当信道条件较好时,新型HARQ的通过率和平均重传次数与Ⅱ型HARQ接近;当信道条件恶化时,新系统的通过率和平均重传次数和Ⅲ型HARQ接近。

On the basis of the type- Ⅱ and type-Ⅲ HARQ（Hybrid Automatic Repeat reQuest） system and RCPT（Rate Compatible Punctured Turbo） code, we present a new HARQ system by combining the subpacket transmission scheme with the averaged diversity combining technique. Our new system＇s performance is the same as that of HARQ Ⅱ when HARQ Ⅱ performs better that HARQ Ⅲ. Its performance is the same as that of HARQ Ⅲ when HARQ Ⅲ performs better than HARQ Ⅱ. In the new HARQ system the diversity combining of a data packet and its copies in the retransmissions is converted into the diversity combining of the identical sub-packets in one data packet. A new interleaver designed for the new HARQ system is helpful to the combination of parity sub-packets of RSC2 of Turbo code. In addition the delay for interleaving Turbo code in new HARQ system is decreased greatly. The minimum distance of Turbo code of the new HARQ system is much increased. The new HARQ system has the advantages of type- Ⅱ and type- Ⅲ HARQ system. When the type- Ⅱ HARQ has higher throughput than the type- Ⅲ HARQ at higher SNR（signal to noise ratio）, the throughput and the retransmission times of the new system are close to type- ⅡHARQ. The new HARQ system spares the redundancy bits, whereas the type-Ⅲ HARQ retransmits too much redundancy at higher SNR. On the other hand when the type-Ⅲ HARQ has higher throughput than the type-Ⅱ HARQ at lower SNR, the throughput and average retransmission times are close to the type-Ⅲ HARQ. Unlike the too many retransmission times of type-Ⅱ HARQ in the lower SNR, the new HARQ spares the number of retransmission times.