为了进一步提高全分集协作( FDC) 系统的可靠性和有效性，提出了两种协作混合自动请求重传( C-HARQ) 方案．定长帧协作混合重传( FFC-HARQ) 方案在不改变全分集协作系统原有帧结构的基础上，使用一定的检错重传策略提高系统吞吐量; 变长帧协作混合重传( VFC-HARQ) 方案则改变原有帧结构，进一步提高系统吞吐量．利用马尔可夫链的状态转移模型，分析了采用FFC-HARQ 和VFC-HARQ 方案时的系统中断概率和吞吐量性能．仿真结果表明，所提方案不但改善了FDC 系统的中断概率，而且提高了系统的吞吐量; 与FFC-HARQ 方案相比，VFC-HARQ 方案在信噪比高于20 dB 时，可获得50% 的吞吐量增益; 而在信噪比为10 dB 时，VFC-HARQ 方案相对于四时隙方案可获得大于10%的吞吐量增益．

In order to improve the reliability and efficiency of the full diversity cooperation ( FDC) transmission system,two cooperation-hybrid automatic repeat request ( C-HARQ) schemes are proposed,one is FFC-HARQ ( Fixed-Length Frame Cooperation-Hybrid Automatic Repeat Request) scheme that adopts the strategy of error detection and retransmission to increase the throughput based on the native frame structure of the FDC transmission
system,and the other is VFC-HARQ ( Variable-Length Frame Cooperation-Hybrid Automatic Repeat Request) scheme that changes the frame structure to further improve the throughput. Then,the outage probabilities and throughput performances of the systems respectively adopting VFC-HARQ and FFC-HARQ schemes are investigated based on the state transition model of Markov chain. Simulation results show that,for the FDC transmission system,the adoption of the proposed schemes can not only reduce the outage probability but also improve the throughput,that VFC-HARQ scheme outperforms FFC-HARQ by a throughput gain of 50% at the SNR greater than 20 dB,and that,as compared with the 4-slot program,VFC-HARQ scheme obtains a throughput gain greater 10% at the SNR of 10 dB.