Codec Switching with Threshold Adaptation for Multimedia Streaming over Wireless Local Area Networks
Date Issued
2010
Date
2010
Author(s)
Wu, Zhung-Han
Abstract
In wireless multimedia streaming, the quality of service (QoS) experienced by the multimedia traffic is subject to the channel variation, which is hard to predict. As a result, transmitting multimedia contents reliably in wireless environments becomes a big challenge in wireless communication. In this thesis, a novel cross-layer algorithm is proposed to deal with both the short-term and the long-term channel variations. To cope with the short-term channel variation, the MAC frame error rate (FER) observed by the client is periodically reported to the multimedia server. The multimedia server then adjusts the codec setting for encoding video bit streams by comparing the reported FER to a set of codec switching thresholds. On the other hand, the algorithm adapts the codec switching thresholds periodically with a longer threshold adaptation period to address the effect of the long-term channel variation. Given the wireless channel state and the codec setting used at the beginning of each threshold adaptation period, the media server selects the codec switching thresholds that minimize the expected transient mean square error (MSE) of the threshold adaptation period. The proposed algorithm reduces the number of computation and the simulation results show that the algorithm significantly improves the PSNR by 3 to 5 dB for multimedia streaming over varying wireless channels.
Subjects
multimedia
streaming
codec adaptation
codec switching
MAC FER
wireless networks
Type
thesis
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