CROSS-LAYER OPTIMISATION USING MARKOVIEN CHAINS DESCRIPTION FOR STREAMING MULTIMEDIA SYSTEMS

Packet scheduling is optimized according to the application layer and transmission strategy adaptation at the adaptive medium access control (MAC) and physical layers. However, packet-size optimization at the MAC layer, which can result in good performance in terms of the multimedia quality, as shown in [7] is not considered in previously cited works. In fact, in [7] a joint application and MAC technique is applied to minimize the distortion impact and fulfill delay constraints of the various packets. The cross-layer algorithm proposed in [7] uses Lagrangian formulation which allows maximizing the instantaneous utility, without considering the impact of the users current action on its long-term performance. In wireless multimedia applications, such myopic strategy design can result in unacceptable deterioration in long-term multimedia quality due to the heterogeneous characteristics of the media traffic. Therefore, cross-layer strategies need to be optimized in a foresighted way by considering the effect of current actions on the future performance. Cross-layer optimization using Markov Decision Process (MDP) framework [8] was proposed in [9]. A joint control of packet scheduling at the transmitter and content-aware playout at the receiver is proposed to maximize the quality of media streaming over a wireless link. But, no adaptive MAC packet size selection is considered. In [10], packet scheduling and buffer management in both Application and MAC layers are jointly considered for single scalable video transmission.