ALAVIT: An adaptive layered video transmission for wireless OFDM channels

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• 作者：Fan Zhang^a ; ^bAuthor Vitae ; Anhong Wang^a ; ^{wah_ty@163.com" class="auth_mail" title="E-mail the corresponding author}Author Vitae ; Xiaoli Ma^cAuthor Vitae ; Cairong Xing^aAuthor Vitae ; Bing Zeng^dAuthor Vitae
• 关键词：Wireless video transmission ; OFDM PHY layer ; SVC ; Subcarrier allocation ; Modulation adjustment
• 刊名：Digital Signal Processing
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：55
• 期：Complete
• 页码：13-21
• 全文大小：932 K

文摘

It is well-known that the layered transmission for video bit-streams generated by a layered coding can gracefully accommodate the receivers' heterogeneity in wireless networks. In this paper, we propose a new layered video transmission scheme employing the subcarrier allocation based on the wireless channel characteristics of orthogonal frequency division multiplexing (OFDM) physical (PHY) layer, leading to an adaptive layered video transmission (ALAVIT). In our scheme, scalable video coding (SVC) is exploited to generate the layered video bit-streams; and the resulting base layer (BL) and enhancement layer (EL) bits are modulated differently to obtain their individual wireless symbols. According to the estimated channel characteristics described by the subcarrier channel gains of a connected wireless receiver, subcarriers with good channel quality are allocated to BL symbols for a better protection of these more important bits. In this unicast case, our ALAVIT scheme is demonstrated to provide a much better performance as compared to the state-of-the-art PHY layer techniques such as s-mod and MixCast. This framework is then generalized from unicast to multicast where the problem is formulated into an optimization involving the average bit-error-rate (BER) over all connected receivers. While the complexity of solving this problem remains extremely high for the current OFDM case of 64 or even more subcarriers, we demonstrate by using a case study of 8 subcarriers that the optimal solution indeed offers a better performance than the heuristic solutions.