A staggered-channel-cluster approach to support videomulticast handoff in wireless networks

Video multicast handoff in wireless networks is challenged by various impairments, such as high bit-error-rate, connection disruption and asynchronous stream concatenation. We tackle this problem by proposing a two-stage multicast approach, where a video stream is distributed to a group of access routers using a regular IP multicast. Within a local subnet, each access router further replicates and forwards the stream over a cluster of multicast channels by enforcing a staggered transmission schedule. A mobile host subscribes to all these channels and employs a buffer control to recover errors and to build up necessary backlogs. This approach gives us a scalable way to improve the error recovery rate and to smooth out potential stream gaps caused by the handoff. Some theoretical results concerning the buffer requirements for guaranteeing the seamless handoff are derived. The simulation results reveal that a cluster of three multicast channels along with a couple-second-video-clip buffer deployed in each access router and mobile host are capable of achieving satisfactory seamless video multicast handoff in most of the typical network environments.