Nowadays the peer-to-peer (P2P) systems have been widely deployed for the Internet television and live streaming. The real-time P2P service features advantages of scalability and heterogeneity in the existing network without modifying the underlay infrastructure. However, most of the common IPTV applications did not consider the user's surfing behavior which causes great burden to the IPTV streaming system. In addition, the high churn rate and insufficient upload capacity may lead to the unstable playback smoothness, and result in a poor quality of experience (QoE). In this paper, we propose a QoE-aware content delivery mechanism to distribute the important and instant data first. I-frame chunks near playback deadline are assigned the top priority. We discuss the comparison of overlay performance and demonstrate that the proposed scheme is workable via a series of experiments on OMNeT++.

A critical design issue of Transmission Control Protocol (TCP) is its congestion control that allows the protocol to adjust the endto-end communication rate based on the detection of packet loss. However, TCP congestion control may function poorly during its slow start and congestion avoidance phases. This is because TCP sends bursts of packets with the fast window increase and the ACK-clock based transmission in slow start, and respond slowly with large congestion windows especially in high bandwidth-delay product (BDP) networks during congestion avoidance. In this article, we propose an improved version of TCP, TCP-Ho, that uses an efficient congestion window control algorithm for a TCP source. According to the estimated available bandwidth and measured round-trip times (RTTs), the proposed algorithm adjusts the congestion window size with a rate between exponential growth and linear growth intelligently. Our extensive simulation results show that TCP-Ho significantly improves the performance of connections as well as remaining fair and stable when the BDP increases. Furthermore, it is feasible to implement because only sending part needs to be modified.

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