| The information society is now changing many aspects of our life. In this society, the demand and dependence of the information is the main symbol. With the coming of "INTERNET era", a lot of new information service will be in use, the need for the bandwidth will become more and more, this cause the mismatch between the need and the traditional POTS access network in which 56Kbps Modem and ISDN technologies are dominant. It is urgent for the service provider to find another technology that has more performance-to-price to overcome this mismatch. The CATV broadband access technology is now coming on the "stage" to satisfy the urgent need. Because this technology can fully utilize the enormous bandwidth of the CATV network to transfer the data, the price for transfer data can be greatly decreased; this enables it to be one of the most attractable technology in broadband access network. It is predicted that in the near future, the CATV technology will be greatly used widely.In CATV broadband access network, the technology of upstream channel access is a key technology, and it is always the focus of the research. The performance of upstream channel access technology affect the performance of network, and so on, it is difficult to implement the ideal access technology due to the limit of the technology. And more the technology is now in the laboratory, when it is on commercial use, the price will be very expensive. How to overcome the shortcoming of the technology? The technology of upstream channel access are under research. This paper is concentrated on the following three aspects: (1) The researches about the collision resolution algorithm. The contents include: the researches about the performance analysis of collision resomution algorithm of specification; the performance analysis of CATV network with backward binary exponential backoff, which is a novel algorithm presented by author; the research about the performance of transmission of multiple request to achieve less collision; the reserch about collison resolution algorithm with priority.(2) The researches about the bandwidth allocation algorithm. The contents include: the difference between allocation of contention slots with constant MAP interval and non-constant MAP interval. And when MAP interval is constant, there include dynamic allocation and static allocation.The research about the scheduling algorithm. The contents include: the FCFS algorithm; the FCFS with priority algorithm; the LCFS algorithm and the shortest packet is first served(3) algorithm.The background, status and development of CATV broadband access technology are described in chapter 1. The details of many key technologies in CATV network, including the technology of physics layer, such as modulation and coding technology, allocation of frequency, and the key technology of media access control layer, such as upstream channel access technology, are also described in this chapter. At the end of the chapter, the development of future CATV network and the employment of the upstream access technology in the other network are also described. The collision resolution algorithm in upstream channel is studied in chapter 2. Three CRAs (Collision Resolution Algorithms) for upstream channel access are proposed, by simulation in different condition of networks, the performance of three algorithms are compared with that in specification, the results show that the performance of these three algorithms is all better than specification. And their complexities are not high. In chapter 3, the performance of CATV network that includes allocation algorithm of contention slots with constant MAP interval and non-constant interval. Allocation algorithm with constant MAP interval is deeply studied. Through the analytical model and simulation, the performances of the above two algorithms are compared, the results show that performance of dynamic allocation algorithm is better than that of static algorithm. And other kinds of dynamic algorithm are also proposed and studied.In chapter... |
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