【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.更多还原

【Abstract】 In this paper,we firstly propose an adaptive compensation timing synchronization algorithm,which bases on the analysis of timing synchronization mechanism for CMs of the DOCSIS 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 implementation for the algorithm,which replaces all involved multiply-division operations by add-subtract 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.更多还原