自适应ARQ系统中基于跨层设计的优化方法

针对IEEE 802.16e系统中的混合自动重传请求（HARQ）协议,将数据链路层的子包传输机制与物理层的自适应调制编码技术（AMC）有效地结合,提出一种基于跨层设计的自适应参数优化选择方法,该方法以最大化系统吞吐量为目的,研究了HARQ子包数目和调制编码方式的联合最优解.同时,还给出了考虑链路层HARQ协议的AMC切换门限准则.仿真结果表明,该参数优化方案能够更好地匹配信道的时变特性,在增加少量复杂度为代价的前提下,实现了系统吞吐量的进一步提高.

Cross-layer optimization method in ARQ systems with adaptive modulation

Based on the adaptive hybrid automatic repeat request(HARQ) protocol in IEEE 802.16e systems,a cross-layer optimization method was proposed,which efficiently combined the sub-packet transmission scheme at data link layer and the adaptive modulation and coding(AMC) at physical layer.Following the cross-layer design method,the number of sub-packets and the scheme of modulation and coding were jointly optimized to maximize the system throughput.A novel criterion on the SNR threshold of AMC was also given with taking the HARQ protocol into consideration.Simulation showed that the optimization method can efficiently adapt to the time-varying channel and improve the system throughput dramatically at a very tiny cost of implementation complexity.