一种基于DOCSIS上行信道的自适应补偿定时同步算法  

An Adaptive Compensation Timing Synchronization Algorithm for DOCSIS Up Channel

作　　者：王沁[1] 郭艳飞[1] 宋丽华[1,2] 杜立国[1] 

机构地区：[1]北京科技大学信息工程学院,北京100083 [2]北方工业大学信息工程学院,北京100144

出　　处：《计算机学报》2010年第7期1305-1314,共10页Chinese Journal of Computers

基　　金：北京市科技重大项目"交互式有线数字电视信道传输核心技术开发"(京科技发[2002]188);北京市科技产业化项目"SOC设计服务及重点产品关键技术研究"(D0306008041021)资助~~

摘　　要：基于DOCSIS规范,在分析CM(Cable Modem)定时同步机制的基础上,文中首先提出了一种自适应补偿定时同步算法.通过准确预测定时误差发生时刻并及时给予误差补偿,该算法能够使CM在HFC网络上行TDMA信道上与CMTS建立精确的全局定时同步,为CM正确接入信道并实现业务传输提供了保证.其次,文中进一步将算法包含的乘除运算优化为加减运算,提高算法的通用性,降低其实现的复杂度.该算法目前已经应用在一款自主研发的CMSoC芯片中,实际环境测试结果表明该算法的定时精度为DOCSIS要求的10.24倍,并表现出优良的可靠性.In this paper, we firstly propose an adaptive compensation timing synchronization al gorithm, which bases on the analysis of timing synchronization mechanism for CMs of the DOC- SIS specifications. By accurately predicting the time of which timing errors come up and giving timing compensation in time, the proposed algorithm can make CMs acquire the global timing synchronization to CMTS in（not sure） the HFC upstream TDMA channel, and ensure the CMs access the channel and transmit services correctly. Then, we also describe an optimized imple- mentation for the algorithm, which replaces all involved multiply-division operations by add-sub- tract operations. Thus, the optimized algorithm improves its universality and reduces its complexity. The proposed algorithm has been integrated in an independent design SoC chip for CM, the test results in real network conditions show that, by using the improved algorithm, timing precision of the CM is 10.24 times higher than the request of DOCSIS specifications, and has a good reliability.

关 键 词：定时同步 HDTV DOCSIS CM 混合同轴光纤 

分 类 号：TP302[自动化与计算机技术—计算机系统结构]