基于DOCSIS HFC网络MAC协议的性能仿真

Performance Simulation of the MAC Protocol Based on the DOCSIS HFC Network

DOCSIS协议已经成为HFC网络前端和用户端之间透明地双向传输IP业务事实上的标准。为了深入研究DOCSIS协议中参数配置对系统性能的影响,本文利用OPNET提供的CSF13仿真工具分析了协议中捎带请求、分块和串联对系统性能的影响,比较了截断二进制指数回退算法中各种回退窗口设置的性能差异;最后,在系统负载和CM个数不变的前提下,探讨了MAP(上行信道带宽分配帧)大小、竞争时隙CS的个数以及设置优先级与上行信道接入延时之间的关系,获得了较佳的性能参数,并对今后复杂的性能仿真提供了重要的参考价值。

The DOCSIS specification has become the de facto standard for the transparent bi-directional IP traffic transmission between the HFC network head and customer locations. In order to thoroughly study the influence of parameter configuration in the DOCSIS specification on the system performance, by utilizing OPNET, we firstly evaluate the influence of piggybacking, fragmentation and concatenation on the system performance, and then compare the influence of the different truncated binary exponential back-off windows setting on the system performance. Finally, on condition that the system load and the number of CMs are fixed, the relations among the MAP size, the number of contention slots, priority settings and access delay of the upstream channel are discussed, and the good performance parameters are gained. The article also provides an important reference value for the future complicated system simulation.