基于虚拟调制编码方式的链路自适应优化

Optimized Link Adaptation Based on Virtual Modulation and Coding

链路自适应与混合自动重传是提升无线传输性能的有效技术。链路自适应以牺牲无线传输的部分可靠性为代价提高效率;混合自动重传利用更多的时间资源提高可靠性。显然,链路自适应和混合自动重传分别以效率和可靠性为主要目标,对通信系统进行优化。然而,如何在两者之间取得联合优化,目前尚无有效的手段。对此,提出一种基于虚拟调制编码方式的优化方案,以时间归一化的频谱效率为准则,对链路自适应和混合自动重传进行联合优化。理论分析与WiMaxII下行链路系统的仿真结果表明,相比于传统的链路自适应和混合自动重传机制,该优化方案能够有效提升无线传输的性能。

Link adaptation （LA） and hybrid automatic repeat request （HARQ） are demonstrated to be effective methods to enhance performance of wireless transmissions. Link adaptation promotes efficiency by partially decreasing robustness of wireless transmissions, whereas hybrid automatic repeat request is contrary. It is obvious that LA and HARQ make optimization with the aims of efficiency and robustness respectively. However it is still tricky to balance LA and HARQ within the same system. To this issue, a virtual modulation and coding based scheme was proposed. With the criterion of time domain normalized spectrum efficiency, LA and HARQ were jointly optimized. Comparing to conventional scheme, theoretical analysis and simulation results from WiMaxII DL system have shown that the proposed scheme will achieve better performance for wireless transmissions.