Enhancing QoS for Streaming Video over WLANs

Recent times have seen a tremendous surge of multimedia traffic over the Wireless Local Area Networks or WLANs. However, the bandwidth intensive multimedia traffic takes the most brunt when a WLAN is overloaded. Longer packet delay, jitter and lower throughput deteriorate the video quality significantly at the receiving end, thus diminishing the user experience. In this paper, we implement a new scheme to guarantee Quality of Service (QoS) for resource intensive traffic such as video even in times of resource scarcity in the network. We accomplish this by prioritizing certain (but not all) video packets and ensuring resource allocation to these packets over others. We also ensure that such preferential treatment to one class of traffic do not rob other low priority traffic of their fair share of resources. This scheme is implemented in the interface between the Logical Link Control (LLC) layer and the Media Access Control (MAC) layer of an 802.11 protocol stack. Extensive simulations over the NS-2 platform shows that our scheme leads to significant improvement in video quality at the receiver end while still retaining the QoS requirements for other traffic like audio and ftp, within acceptable bounds.