Technical Study Of Concentrator In HFC Broadband Access Network

With the rapid development of Internet network, people's demands on broadband services, such as remote instruction, telecommuting, telemedicine, Visual telephone, VOD, WWW browse, are increasing sharply. E-business has also becomes a big hotspot. As a result, the technology of broadband access network, "the last kilometer" of information superhighway, is developing promptly. HFC network is catching more and more attentions because of its particular advantage of bandwidth and high popularization.This paper firstly studies the architecture of the hybrid-fiber-coax (HFC) network and its advantages as a broadband access network. The author also studies and analyzes its existing problems and relevant solutions. Then according to the study, the author, combining the modern communications technology, brings forward a new scheme of HFC broadband access network. The new scheme has a lot of advantages such as resolving "the funnel noise" in the upstream channel, high speed and low cost of building, which is likely to become an important broadband access network. This paper focuses on the realization of the concentrator, which is an important device in the new HFC broadband access network. Although the concentrator based on HFC is a fully new device, it will become the key device on information superhighway with the popularization of the new scheme. Therefore, the project is not only academically valuable but also practically useful. In the course of studying and designing the concentrator, we firstly analyzed its function, defined its function module and also selected Ethernet switch to implement switch module. In addition, we also put forward the method of how to receive the digital TV signals and how to transmit them in the Ethernet. On choosing chips we emphasized on high integration, and in this paper the author discussed in detail their functions. For the operating system, we choose the best and popular one, VxWorks,whose rich network components and multitask programming idea benefit the software development. In order to improve the efficiency of transmission, receiving TS data packet on CPU's GPIO port and transmitting data on CPU's PCI port are processed in different priority. To improve the communications efficiency, we adopt the multicast to deliver the digital TV to relevant user. In summary, those technologies have very important foreground of application, which also have important value of reference to others.