362 IEEE TRANSACTIONS ON BROADCASTING, VOL. 53, NO. 1, MARCH 2007 Resource Efficient Quality-Oriented Wireless Broadcasting of Adaptive Multimedia Content Gabriel-Miro Muntean, Member, IEEE, and Nikki Cranley, Member, IEEE Abstract—The performance of multimedia stream delivery is influenced by encoding scheme, streaming solution and network conditions. This paper studies the performance of multimedia streaming when using the Quality-Oriented Adaptive Scheme (QOAS) over an IEEE 802.11b Wireless LAN and compares it to that achieved when using other solutions that do not consider end-user quality in their delivery process such as TFRC, LDA , and non-adaptive schemes. The performance is assessed in terms of average end-user perceived quality, number of concurrent streaming sessions, loss rate, delay, jitter and total throughput when streaming MPEG-4 encoded content. Simulation results show that the QOAS out-performs these other streaming solu- tions in all aspects of network delivery. QOAS can support a greater number of concurrent streaming sessions at a higher average quality. In addition, for the same number of clients QOAS achieved a higher average end-user quality, as well as better network delivery streaming performance parameters. Index Terms—Adaptive multimedia streaming, end-user quality of experience, wireless local area network. I. INTRODUCTION F LEXIBILITY of user location, mobility and low deploy- ment costs are key factors that are driving the exponen- tial growth in the usage of wireless technologies for distribu- tion of services at business premises or residential homes [1]. This trend includes the deployment of Wireless LANs (WLAN) that enable users to access various services including those that distribute rich media content anywhere, anytime and from any device. Fig. 1 shows such a WLAN-based solution [2] for ef- ficient distribution of multimedia content over wireless links. The architecture includes a Smart Access Point (SAP) that acts as a server and provides services to multimedia-enabled clients. Content is either received at the SAP via a wired broadband connection or is acquired locally from a source such as a video camera, DVD player, hard disk, etc. There are many performance issues related to the usage of wireless networks especially in relation to the delivery of high bit rate time-sensitive stream-oriented content using current IEEE 802.11 standards, which were primarily designed for best effort services. Among the most significant are low delivery Manuscript received June 13, 2006; revised November 10, 2006. This work was supported by the Enterprise Ireland Commercialization Fund—Proof of Concept phase. G.-M. Muntean is with the School of Electronic Engineering, Dublin City University, Dublin 9, Ireland (e-mail: munteang@eeng.dcu.ie). N. Cranley is with the Communications Network Research Institute, FOCAS Institute, Dublin Institute of Technology, Dublin 8, Ireland (e-mail: nikki.cranley@cnri.dit.ie). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TBC.2007.891710 Fig. 1. Wireless architecture for distribution of multimedia content. rates (e.g. theoretically up to 11 Mbps for IEEE 802.11b, but in practice only a throughput of approximately 6 Mbps can be achieved) and high error rates due to delivery media characteristics, contention between stations for access to the medium, back-off mechanisms, collisions, signal attenuation with distance, signal interference, etc. In these conditions it is difficult to provide any Quality of Service (QoS) guarantees. There are several significant adaptive solutions that provide a certain level of QoS in variable network delivery conditions such as the TCP-Friendly Rate Control Protocol (TFRC) [3] and the enhanced Loss-Delay Adaptation Algorithm (LDA ) [4]. These solutions offer good network-related results when streaming multimedia over wired networks, but are poorly designed for use over wireless networks and do not include end-user perceived quality in the adaptation process. Recently diverse solutions have been proposed for scalable multimedia transmissions over wireless networks [5] or wireless ad-hoc networks [6]. Among these are adaptive algorithms that op- erate at the level of layers [5] or objects [7], fine-granular scalability schemes [8] and perception-based approaches [9]. Complementing these approaches, the emerging IEEE 802.11e standard will provide QoS capabilities that can be used to improve end-user Quality of Experience (QoE) by allowing for dynamic prioritization of multimedia services. This paper presents the Quality-Oriented Adaptation Scheme (QOAS) [10], [11], an adaptive multimedia streaming solution which is based on user QoE that maximizes end-user perceived quality in highly variable and increasingly loaded network delivery conditions. Simulation results for streaming multi- media over an IEEE 802.11b WLAN are compared when using QOAS, TFRC, LDA and a non-adaptive (NoAd) approach. Testing involved monitoring network delivery parameters and end-user perceived quality whilst increasing the number of 0018-9316/$25.00 © 2007 IEEE Authorized licensed use limited to: DUBLIN CITY UNIVERSITY. Downloaded on September 2, 2009 at 10:27 from IEEE Xplore. Restrictions apply.