The Research On The Key Techniques Of Intercommunication In HFC Network

The key problem on the intercommunication is that noise converge in up channel will have a serious influence on the quality of bi-directional communication. At the same time, when the intercommunication was achieved, if the level difference between networks up and down direction distributed by coaxial cable is very big, it may generate the interactive modulation. In addition, these problems on the up channel contest and distribution are technical difficult in the reconstruction of the bi-directional transmission HFC network. This paper compares the current bi-directional reconstruction of the HFC with others, and proposes the design projects of intercommunication on the base of traditional structure. Also, with the technical problems on the constraint in up channel transmission, the implementation and flow are designed to carry out all kinds of services (such as audio & video, data services, internet communication and so on) and construct so called "Integrated Services Network".There are five important problems to be discussed in this paper. Firstly, we analyze and compare the present techniques of HFC network, and point out the disadvantages of the HUB-based distribution network. Secondly, we demonstrate the feasibilities of tree-topology distribution, and focus the dissertations on the most difficult part of coaxial cable distribution network. Thirdly, with the choice among the techniques used in up and down channel transmission, the specific applied method of the CBR (Constant Bit Rate) and VBR (Variety Bit Rate) in the HFC network by the ATM-based transmission are given, thus these services such as broadcast, multicast and order programme are achieved. Fourthly, the up channels from multi-point to single-point are similar to data-bus in the HFC, so the collisions should be avoided and solved. We can conclude that Token-Bus is perfect, but the IEEE 802.4 standard is so complex that we have made some necessary modifications in our design. So the speed of token circulation would be obviously increased, and the dynamic distribution and availability of bandwidth may be realized and improved by the level of token. Lastly, with the design of the HFC network management, we compare two models between the TMN-based network and the INTERNET-based network. In this paper, we adopt the TMN technique, and combine the correlative criterions of broadcast and the features of HFC services, to reconstruct the models and import the new variants.