Optimization of downstream delivery on a CATV network

CATV networks can offer a very high bandwidth for the delivery of advanced multimedia services such as video-on-demand, video conferencing, and video broadcasting. In this paper, two channel allocation problems for downstream delivery on a CATV network are described, namely the Unicast Channel Allocation Problem (UCAP) and the Multicast Channel Allocation Problem (MCAP). The UCAP is formulated to allocate unicast video channels such that the number of active terminals is maximized. An efficient channel allocation scheme is proposed and the number of established streams is maximized. The MCAP is formulated to allocate multicast video channels such that the total communication cost is minimized. A lower bound is derived and an efficient approximation algorithm is proposed. We prove that the proposed algorithm always produces a solution no greater than twice of the lower bound. Finally, a cost performance simulation on the terminals attached to the cable is made. The result indicates that only a small set of channels is enough for each terminal to request the downstream services.