WEBS : WiMAX emulation testbed to benchmark streaming multimedia QoS

New generation multimedia applications over broadband wireless networks like WiMAX¹ consume relatively large amount of battery power. Most of the studies in this field have been focused either on the power conservation or the video quality evaluation aspect of WiMAX based on early stage simulations. However, Network emulation studies are preferred during design phase to guide product designs. To the best of our knowledge no emulator has been reported that evaluates power saving algorithm's impact on perceptual quality of video over WiMAX. In this paper we describe WEBS, a novel WiMAX network emulation testbed based on the well accepted Qualnet simulator to benchmark quality of streaming video along with its impact on energy conservation mechanism in WiMAX. In particular we observe in our emulation that irrespective of the motion content in the video, the WiMAX subscriber device spends around 45 to 55% time in sleep mode during the video streaming period for our simulation parameters. The perceptual distortion in case of videos having greater motion component is around three times greater than those having lower motion components for the same coding bit rate. We also find that for moderate motion content videos, the perceptual distortion when operated with the power saving mode enabled is almost equal to that when operated without it. Thus our results show that for low and moderate motion content videos, by enabling power saving on the WiMAX device, battery life time can be extended by approximately 50% without having to reduce video quality.