Cross-Layer QoS Control for Video Communications over Wireless Ad Hoc Networks
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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: [email protected], [email protected]
2 Department
of Electrical & Computer Engineering, University of California, San Diego, La Jolla, CA 92093-0407, USA Email: [email protected]
3 Department
of Computer Science & Engineering, College of Engineering & Computer Science, Wright State University, Dayton, OH 45435-0001, USA Emails: [email protected], [email protected]
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 of the 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 network, packets are sent from node to node in a multihop fashion until they eventually reach the intended destination. As multimedia is expected to be a major traffic source on next-generation wireless networks, there has been increasing research interest in the delivery of multimedia services over such wireless ad hoc networks [1, 2, 3]. A data partitioning scheme, together with multipath routing for protecting against failures of links due to topological changes and packet losses due to fading effects, was presented in [1, 2] assuming perfect network state information. In [3], a source coding-based approach using multiple description coding is presented to take advantage of path diversity as a means to improve packet-loss resilience. However, these works, as well as much previous work appearing This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
in the literature, target the problem from an individual user’s point of view without consider
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