1052 IEEE TRANSACTIONS ON MULTIMEDIA, VOL. 11, NO. 6, OCTOBER 2009 A Cross-Layer Approach to Multichannel MAC Protocol Design for Video Streaming Over Wireless Ad Hoc Networks Byung Joon Oh, Student Member, IEEE, and Chang Wen Chen, Fellow, IEEE Abstract—This paper presents a cross-layer design for a reliable video transmission over wireless ad hoc networks based on mul- tichannel MAC protocol with TDMA. First, we conduct a study of the multichannel MAC protocol through Markov chain model. Based on this study, two novel cross-layer modules are adopted for the design of multichannel MAC protocol. First, we adopt max- imum latency rate (MLR) as the channel quality metric. Unlike the traditional MAC design based on network allocation vector (NAV), MLR is implemented to provide differentiated traffic so that the channel with smaller MLR time is initiated for higher priority traffic. Second, we adopt two congestion-aware metrics, namely MAC utilization and queue length of MAC layer, to improve the congestion-aware routing protocols with AODV and DSR. These two novel modules allow the proposed MAC protocol design to achieve high performance video transmission over wireless ad hoc networks. Experimental results show that the proposed scheme outperforms the state-of-the-art schemes under multichannel environments in wireless ad hoc networks for as much as 3.6 dB in PSNR. Such significant performance enhancement confirms that the cross-layer approach is very effective for multichannel MAC protocol design. Index Terms—Cross-layer design, H264/AVC, maximum latency rate (MLR), multichannel MAC, network allocation vector (NAV), TDMA MAC. I. INTRODUCTION W ITH recent advances in wireless mobile ad hoc network (MANET) and the proliferation of H.264 video coding standards, video streaming is becoming common for wireless ad hoc networks. Without integrated access points or base stations, mobile stations in MANET can communicate with each other directly under power constraint, intervention, and channel effect limitations. Even though current IEEE 802.11a/b/g/n physical layer (PHY) [1] can support the use of multiple channels making use of multiple frequency bands without any obstruction with each other, mobile stations in ad hoc mode and infrastructure mode are often limited to one channel under current standard protocols [2]–[5]. Manuscript received October 17, 2008; revised April 07, 2009. Current ver- sion published September 16, 2009. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Aggelos K. Kat- saggelos. B. J. Oh was with the Florida Institute of Technology, Melbourne, FL 32901 USA. He is now with Link Communications, Ltd., Annapolis Junction, MD 20701 USA (e-mail: byungjoonoh@lnkcom.com). C. W. Chen is with the Department of Computer Science and Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 USA (e-mail: chencw@buffalo.edu). Digital Object Identifier 10.1109/TMM.2009.2026083 In order to increase the throughput and to reduce the delay of the ad hoc networks, multichannel MAC protocols have been proposed in [6]–[8]. Unfortunately, these protocols cannot be directly adopted to achieve higher quality delivery of time-bound applications such as VoIP and video streaming [6]–[11], [13] because these time-bound applications also require stringent quality-of-service (QoS) constraints such as video packets loss rate, throughput, and packet delay. Most of these existing approaches in multichannel MAC only showed improved throughput comparing with single channel MAC. Ex- isting research in QoS driven H.264 transmission over wireless ad hoc networks [2], [3], on the other hand, have assumed only single channel MAC with IEEE 802.11e standard [4]. It is clear that multichannel MAC protocol design will ben- efit from a cross-layer design, especially for time-bound video streaming applications, since the overall QoS of time-bound applications depends on multiple QoS metrics including throughput, packet loss rate, and packet delay [6]. Multichannel MAC architecture will be able to support the specified channel for video packet without contention and reduced congestion in MAC layer level in order to minimize the video packet loss rate. A cross-layer design also provides the wireless channel information and the status of the lower level through all layers up to the application layer (video packets) to reduce the video packet loss rate. However, there have been little research to take full advantage of both cross-layer and multichannel design [10], [11] and explicitly consider the QoS constraints for time-bound applications. Among the existing approaches, the authors in [6] presented various analysis and simulations based on several existing mul- tichannel MAC protocols. They categorized these protocols into four classes as dedicated control channel, common hopping, split phase, and multiple rendezvous. They compared the perfor- mances of multichannel protocols with respect to the effects of the number of channels, channel switching times, and traffic pat- terns on throughput and delay. However, these analytical models for the four protocols using Markov chains cannot be adopted di- rectly for video streams with cross-layer coupling since the eval- uation of packet loss impacts on video reception is not straight- forward. Recently, Zhang et al. proposed a TDMA-based multichannel MAC (TMMAC) protocol over ad hoc networks [7]. It was shown that TMMAC can automatically adapt its negotiation window size depending on different traffic patterns. With such adaptation, TMMAC not only performs up to 113% higher com- munication throughput but also dissipates 74% less energy per 1520-9210/$26.00 © 2009 IEEE Authorized licensed use limited to: Amirkabir Univ of Tech Trial user. Downloaded on June 06,2010 at 13:26:36 UTC from IEEE Xplore. Restrictions apply.