I. Introduction
Video has become one of the most important forms of media in our lives. On average, each household has 1.4 television sets in the U.S. [3]. With the availability of networks, people also wish to be able to access videos instantly at the touch their fingertips. With the advancement of broad-band networking technology, computing technology, and storage technology, VOD (video-on-demand) services have become possible [18], [20]. Offering such services is likely to be popular at local residential areas, and viable in metropolitan areas in the near future.