Adaptive low-complexity erasure-correcting code-based protocols for QoS-driven mobile multicast services

Abstract

We propose an adaptive hybrid ARQ-FEC erasure-correcting scheme for QoS-driven mobile multicast services over wireless networks. The main features of our proposed scheme include: the low-complexity and dynamic adaptation to the variations of packet-loss levels and QoS-requirements. The low complexity is achieved by using the graph-code with linear time-complexity. To support diverse QoS-requirements and improve the error-control efficiency, we develop the two-dimensional adaptive error-control scheme, which dynamically adjusts not only the error-control redundancy, but also the code-mapping structure. By deriving and identifying the closed-form non-linear expressions for the optimal check-node degree and the required error-control redundancy in each adaptation step as the functions of the packet-loss level, we propose the non-uniformed two-dimensional adaptive coding scheme. Using this scheme, we develop an efficient hybrid ARQ-FEC protocol for mobile multicast services with diverse QoS requirements. Also conducted is a set of numerical and simulation results which analyze and compare our proposed adaptive scheme with those using the non-adaptive graph codes, Reed-Solomon erasure codes, and pure ARQ-based approach. The simulation results show that our proposed scheme can efficiently support QoS-driven mobile multicast services and achieve well-balanced error-control redundancy while imposing low error-control complexity and overhead for mobile multicast services over wireless networks.