An Optimal Rate Assignment Mechanism for Multimedia Transmission over the Down-Link of IS856

This paper presents an optimal rate assignment mechanism for multimedia transmission over time-varying channels (e.g., the down-link of wireless network IS856 - cdma2000 1timesEv-DO). The proposed method allocates the resources optimally to maximize the delivered quality of service (QoS), which is measured by the average delivered distortion. This optimal mechanism assumes that the scheme used to encode and decode the multimedia information has the embedded property; besides, it assumes that scheduler knows the instantaneous air-link capacities. By taking advantage of the embedded property of the encoding scheme, the proposed optimal rate assignment mechanism adapts the source encoder´s rate dynamically, based on its air-link capacity, to deliver the best possible quality of service. As a result, the wireless network (e.g., IS856) can utilize its resources more efficiently, and thus, it can accommodate a higher number of multimedia sessions. Simulation results show that by using the proposed rate assignment a gain of up to 100% in system capacity can be achieved