Supporting multimedia quality of service (qos) in wireless networks
Chang Wen Chen, Byung Joon Oh · 2008
The demand for high quality multimedia transmission over wireless networks is growing at an explosive rate. However, the significant obstacles are the fundamentally limited channel bandwidth and the unpredictability of wireless obstacles. IEEE 802.11e standards have recently emerged as one of the most prominent techniques to overcome such obstructions. This dissertation addresses the multimedia Quality of Service (QoS) in wireless networks. The primary objective is to investigate the reliability of VoIP/video transmission schemes with the IEEE 802.11e standard as well as state-of-the-art technology in contexts of both theoretical and practical approaches. Above all, for VoIP transmission, which is more sensitive to packet delays than video transmission, to complete higher capacity of VoIP, the Markov chain model and the EDCA MAC are implemented. Furthermore, we can foresee the effect of error control through GOP-level estimator of decodable slice rate (GEDSR) and channel state estimation (CSE) within wireless infrastructure networks. Namely, the adaptive cross-layer feedback mechanism based on channel status validates its efficiency for the QoS metric on H.264/AVC video transmissions over wireless error prone channels. Secondly, the QoS metrics of video streaming using EDCA MAC is more attractive than high rate transmission scheme using the dual mode IEEE 802.11b/g based on physical rates because video streaming of Ad Hoc networks has more constraints than that of Infrastructure networks. For that reason we present a reliable video streaming using EDCA MAC and the dual mode IEEE 802.11b/g physical layer over Ad Hoc networks. To overcome the drawback of the IEEE 802.11e standard, we suggest more adaptive EDCA with a more energy efficient FHSS (BFSK) scheme to promote energy conservation during transmission. Consequently, we extend a novel adaptive EDCA by adjusting the Contention Window according to the current network status. To implement an energy efficient transmission that adapts to network conditions, we have merged the adaptive scheme with an energy efficient estimator (E3 metric) that is developed to support the selection of modulation schemes. Moreover, we propose state-of-the-art technologies such as cross layer design, multi-channel MAC, and multi-rate MAC to support video streaming over wireless Ad Hoc networks.