Realization Of Dual Downstream Channel Of CMTS In HFC Network

With the development of society and technology, people's demand on broad band services, such as VOD, Visual telephone and Internet, are is increasing constantly. Broadband-access network, "the last mile" of information superhighway, is developing rapidly. HFC network is catching more and more attention because of its particular advantage of bandwidth. To meet the demand on broad band services, the methods providing dual downstream channel in one CMTS were studied in this thesis.In this paper, the hybrid-fiber-coax network's topology, architecture, characters of the channel, and the network service were plenty studied. After anatomizing DOCSIS protocol, we point out the disadvantage of single downstream channel, and discuss the realization of dual downstream channel. In this thesis, works were done hardly over the strategy of CM changing downstream channel dynamically and CMTS balancing the resource of channel. The mostly technical problems were resolved, such as: how to distinguishing and initialing, how to establish interconnection of courses, how to check the resource of channel, and so on. In the implementation, we used the multiprocessing method in QNX to analyze the general flow chart of system, and divided the realization of dual downstream channel into three modules. Finally, this paper shows the original codes of message queue, bandwidth checking, and channel switching.