Link layer algorithms for efficient multicast services in 3G multicellular systems

We introduce error control algorithms for multicast delivery in 3G cellular networks. For efficiency reasons, the delivery of multicast flows is usually achieved by allocating a common channel in the forward direction. This enables multiple users to be served by a single physical resource. However, different users are affected by independent channel error processes and new techniques, different from plain ARQ, have to be found to perform error recovery. These new algorithms are needed to deliver the multicast flow in an efficient manner and to enable a reliable, performant and network operator inexpensive, multicast service. Different hybrid ARQ algorithms for the error recovery of multicast flows over common channels are proposed and their performance is evaluated both analytically and by simulation. The proposed solutions have been found to be effective and advantageous over plain ARQ techniques. Results on the achievable video quality are reported for the multicast video streaming case by considering the H.263 video coding format.