An analytical model for quality of experience of HTTP video streaming over wireless ad hoc networks

HTTP video streaming employs the TCP protocol as its transport protocol, which provides reliability on one hand, but delay or delay jitter on the other hand. IEEE 802.11 MAC protocol is assumed to support wireless networks, whose channel access efficiency impacts the performance of the upper layer, i.e., the data rate and the delay of TCP. In this paper, an analytical model for Quality of Experience (QoE) of HTTP video streaming over single-hop wireless networks is proposed. Particularly, two QoE performance metrics are evaluated, which are underflow times and fluency of playout, defined as the buffer empty times during playout, and the ratio of ideal watching time to the real watching time. The impacts of system parameters, such as the length of a video file, the playout threshold, the playout rate, and the arriving rate of a TCP streaming, on the system performance metrics are analyzed in detail. It is found that when both the TCP congestion window and the MAC contention window are set to one, the arriving rate of a TCP streaming can achieve its maximum, which results in the optimal QoE performance. Moreover, the optimal setting for the MAC contention window is also obtained for the case that the TCP congestion window is larger than one. The accuracy of the proposed analytical model is verified by extensive simulations.