Short Message Return-based VOD In CATV Network

The development of multimedia technology and broadband network have created fairly good condition for Video On Demand (VOD) technology. Being difference with the traditional broadcast television, people can choose their favorite program at any time in VOD sysytem, while not waiting for the regularly schedules of TV broadcasting. But the difficulties VOD meets are also enormous, because of the constant growth of user's quantity, the bandwidth of the network becomes the bottleneck which restricts the improvement of service ability, especially for the cable television system as sharing network, the video and audio streams it can load are much lower than the request quantity by users. In the VOD system, the transmit way of the user's request is related to the network structure of the system. If adopt the upstream channel of HFC directly, the present HFC network shall be processed with large-scale bi-directional transformation, which cannot be polularized throughout the country at present. Meanwhile, the mobile communication network of our country has been already developed maturely with the high popularity of the cell-phone, to transmit request signals by adopting wireless network will be speedy and convenient, and inaddition, it just need a little equipment investment of the cable TV providers. It offers anther method especially for the small and medium cities having not finished the bi-directional transformation of the HFC network. The network principle, service ability and support to VOD service of CATV network based on HFC are systematically summarized in the paper; the video compress and transmission technology of the digital TV are researched and the composition and principle of VOD systematic are analysed; according to the characteristic of the present CATV network of our country, we propose a Short Message Return-based VOD system which transmit the demand of the users by GSM/CDMA wireless network and download the video streams by CATV network. Because of the bandwidth characteristic of the cable television network, the service ability of providing vod service for user at the same time is very limited, in order to offer video on demand service for more users with the limited network resources, the scheduling strategy of user's request will be the ulmost important. On the basis of studying user's requesting characteristic, the program access rate and VOD type, referring the relevant concepts in the operating system, we propose a kind of dispatcher algorithms based on PRI of the request. Through classifying the service type reasonably and dealing with user request appropriately, this system could provide VOD service for more users in the request delay range the user could bear.