Based On The Key Technology Of A Docsis Hfc Broadband Internet Line Channel

Nowadays, the society has become "Information Society". People demandmuch more effective manners to gain and transmit information. The traditionalPSTN access network cannot satisfy the urgent need any more. Thus, HFCbroadband access network is now coming on the "stage"with the specialty-widely covering and abundance bandwidth. The DOCSIS specification isestablished as the primary HFC network data communication standard. Becauseof the structure character of HFC, DOCSIS makes use of upstream channel inTDMA mode and allocate it by "request-grant"mechanism. So there are a seriesof technical difficulty. The technology of upstream channel access is a keytechnology, and it is always the focus of the research.The key technologies of upstream channel of the HFC are under research, baseon DOCSIS. This paper is concentrated on the following three aspects:(1)The primary problems of upstream channel are analyzed, and the mend ofHFC is present. It makes CMTS to be provided with the ability to detect thecollision. The collision resolution algorithm based on detecting collision isdesigned. It can adjust the "backoff windows"according to the degree ofcollision. Thus, it can decrease the collision effectively to adapt the change ofuser.(2)The contradiction of collision resolution and access delay is researched. Thecollision resolution algorithm based on priority is designed to solve thecontradiction. It makes the high priority user to have lower access delay.According to the priority, the collision resolution and the fist-time access of thehigh priority user are guaranteed, and the low priority user is served by its besteffort.(3)The connection of contention slot and data slot is analyzed. According tothe connection, the dynamic allocation of slots is designed. It validates the effectof the connection in the networks.