This paper presents an improved predictive tuning method that satisfies required channel zapping time with minimized bandwidth usage. One way to reduce channel zapping time is a predictive tuning method, which reduces channel zapping time by prejoining channels that are likely to be selected next, in addition to the currently watched channel. ![]() Furthermore, this simple scheme has a performance close to that of an ideal predictor, while the increase of bandwidth utilisation in the access link is negligible.Ĭhannel zapping time is a crucial issue in Internet Protocol Television (IPTV) Quality of Experience (QoE) performance. As an example, by sending the previous and the next channel concurrently with the requested one, for only one minute after a zapping event, switching delay is eliminated for around 45% of all channel switching requests. Notwithstanding the simplicity of this scheme, trace-driven simulations show that the zapping delay can be virtually eliminated for a significant percentage of channel switching requests. If the user switches to any of these channels the switching latency is virtually eliminated, not affecting therefore user's experience. Our proposal is to send the neighbouring channels (i.e., channels adjacent to the requested one) to the Set Top Box (STB) during zapping periods. This fact led us to the proposal, in this paper, of a simple mechanism to reduce channel switching delay. By analysing an extensive dataset - comprising 255 thousand users, 150 TV channels, and covering a 6-month period - we have observed that most channel switching events are linear: it is very common the user switching up or down to the next TV channel. This delay can add up to two seconds or more, and its main culprits are synchronisation and buffering. One of the major concerns of IPTV network deployment is channel switching (or zapping) delay. Other more complex schemes where user behaviour is tracked were also evaluated, but the improvement over the simple scheme was insignificant. Importantly, this result is achieved with a negligible increase of bandwidth utilisation in the access link. For example, when sending the previous and the next channel concurrently with the requested one, for only 1min after a zapping event, switching delay is eliminated for close to half of all channel switching requests. ![]() If the user switches to any of these channels the switching latency is virtually eliminated, not affecting therefore user's experience.We start by evaluating a simple scheme, where the neighbouring channels (i.e., channels adjacent to the requested one) are pre-joined by the STB during zapping periods. In these schemes each set top box (STB) simultaneously joins additional multicast groups (TV channels) along with the one that is requested by the user. This fact motivated us to use this dataset to analyse in detail a specific type of solutions to this problem, namely, predictive pre-joining of TV channels. We start this paper with a survey of techniques proposed to reduce IPTV channel change delay.Then, by analysing an extensive dataset from an operational IPTV provider – comprising 255 thousand users, 150 TV channels, and covering a 6-month period – we have observed that most channel switching events are relatively predictable: users very frequently switch linearly, up or down to the next TV channel. Proving the importance of the problem is the already significant amount of literature addressing it. This delay can add up to 2s or more, and its main culprits are synchronisation and buffering of the media streams. One of the major concerns of IPTV network deployment is channel change delay (also known as zapping delay).
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