ارزیابی عملکرد جریان ویدیویی مبتنی بر HTTP فرستنده-کمک در شبکه های ad hoc بی سیم

HTTP Adaptive Streaming (HAS) delivers video streaming services according to a client–server architecture where the client originates consecutive HTTP requests to download chunks of encoded video. In state-of-the-art systems, the client selects the chunk out of a finite set of differently encoded versions of the same video made available at the server site; the selection is driven by a client-centered buffer management procedure. Still, dynamic bitstream switching may have drawbacks in terms of undesirable visual quality fluctuations artifacts at the final user; besides, it may result in oscillatory behavior of the overall traffic in case of multiple users. Therefore, this paper proposes a sender-assisted procedure for HTTP Adaptive Streaming (HAS) services with improved user Quality of Experience (QoE) that proactively avoids buffer underflow events at the receiver side, thus reducing the need for dynamic bitstream switching. In the proposed sender-assisted approach, HAS leverages information on the encoded video available at the server side to assist the client in originating the data requests. Specifically, the sender-assisted HAS procedure exploits information on the encoded video content available at the sender side to regulate the interval between consecutive client-originated download requests. Significant QoE improvements brought by the proposed sender-assisted video streaming procedure are demonstrated in challenging fluctuating throughput conditions encountered in wireless ad hoc networks.