2 research outputs found
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Wireless video streaming for single-hop networks
Limited bandwidth and high packet loss rate pose a serious challenge for video streaming applications over wireless networks. Even when packet loss is not present, the bandwidth fluctuation as a result of an arbitrary number of active flows in an IEEE 802.11 network, can significantly degrade the video quality. This paper aims to enhance the quality of video streaming applications in wireless home networks via a joint optimization of video coding technique, admission control algorithm, and Medium Access Control (MAC) protocol. Using an Aloha-like MAC protocol, we propose a novel admission control framework, which can be viewed as an optimization problem that maximizes the average quality of admitted videos, given a specified minimum video quality for each flow. We present some hardness results for the optimization problem under various conditions, and propose some heuristic algorithms for finding a good solution. In particular, we show that a simple greedy layer-allocation algorithm can perform reasonably well, although it is typically not optimal. Consequently, we present a more expensive heuristic algorithm that guarantees to approximate the optimal solution within a constant factor. Simulation results demonstrate that our proposed framework can improve the video quality up to 26% as compared to those of the existing approaches
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Traffic models for MPEG-4 spatial scalable video
MPEG-4 spatial scalable encoding scheme (SSES) provides different resolutions and wide range of VBR, (variate bit rate) video to satisfy requirements of end users with variant screen resolutions and network bandwidth. In a SSES, one base layer traffic and one (or more) enhancement layer(s) traffic are generated. Although many traffic models have been developed for single layer video traffic, none exists for VBR, SSES video traffic. Our extensive studies suggest that MMG (Markov-modulated gamma) model can capture base layer traffic quite well. However, it cannot be used for modeling enhancement layer traffic for two reasons: (1) enhancement layers have no I-frames, (2) enhancement layer traffic and base layer traffic are not independent and have a strong correlation. In this paper, we propose two models for enhancement layer traffic and aggregate traffic. To maintain the correlation between base layer and enhancement layers, we augment the base-layer state transition model. The augmentation uses state transition relation between base layer and enhancement layer traffic or between base layer and aggregate traffic. The models have been validated by QQ plots and leaky-bucket simulations. The model generated traffic streams quite accurately mimic original traffic streams