Cross-Layer Optimization for Streaming MPEG4 Video over HSDPA Networks

A novel cross layer optimization technique for efficient streaming of MPEG4 VIDEO over a High Speed Downlink Packet Access (HSDPA) network is proposed in this paper. The proposed technique uses the types of frames produced by the MPEG encoder to optimize the performance of the Hybrid Automatic Repeat reQuest (H-ARQ) protocol at the MAC layer. Our aim is to reduce the total power at the NodeB, and to increase the overall system throughput, while maintaining satisfactory user-perceived Quality of Service (QoS). The proposed technique consists in applying ARQ retransmission for MPEG4 I-frames (the most critical frame of an MPEG4 stream) upon the reception of a negative acknowledgment (NACK) message from the receiver (UE). Packet combining is then performed with the aid of the available I-frames at the receiver side. Different packet combining strategies have been investigated to assess the performance of the proposed cross-layer technique. We show that compared to the blind HARQ Chase Combining scheme applied indiscriminately to all MPEG4 frames, our scheme allows for saving up to 11% of the power at the NodeB, and up to 10% of the system bandwidth, while ensuring satisfactory video quality to users.