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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Cross-Layer QoS Control for Video Communications over Wireless Ad Hoc Networks | EURASIP Journal on Wireless Communications and Networking 2005 5 743-756 2005 Qi Qu et al. Cross-Layer QoS Control for Video Communications over Wireless Ad Hoc Networks Qi Qu 1 2 Yong Pei 3 James W. Modestino 1 Xusheng Tian 1 and Bin Wang3 1 Department of Electrical and Computer Engineering College of Engineering University of Miami Coral Gables FL 33124 USA Emails jmodestino@miami.edu xtian@miami.edu 2 Department of Electrical Computer Engineering University of California San Diego La Jolla CA 92093-0407 USA Email qqu@ucsd.edu 3 Department of Computer Science Engineering College of Engineering Computer Science Wright State University Dayton OH 45435-0001 USA Emails ypei@cs.wright.edu bwang@cs.wright.edu Received 21 June 2004 Revised 12 May 2005 Assuming a wireless ad hoc network consisting of n homogeneous video users with each of them also serving as a possible relay node for other users we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters such as the interference environment the number of transmission hops to a destination and the packet loss rate. Furthermore in order to provide error-resilient video delivery over such wireless ad hoc networks a cross-layer joint source-channel coding JSCC approach to be used in conjunction with rate-control is proposed and investigated. This approach attempts to optimally apply the appropriate channel coding rate given the constraints imposed by the effective transmission rate obtained from the proposed rate-control scheme the allowable real-time video play-out delay and the prevailing channel conditions. Simulation results are provided which demonstrate the effectiveness ofthe proposed cross-layer combined rate-control and JSCC approach. Keywords and phrases ad hoc video transmission throughput capacity effective transmission rate packet delay joint sourcechannel coding. 1. INTRODUCTION In a wireless ad hoc .
