Keynote lecture research challenges and proposed solutions to improve availability and quality-of-service in future IPTV systems

During the last decade the offering of TV programs via the Internet by means of an IPTV service using multicast communication has become more and more common. Currently, the largest number of IPTV subscribers is located in Western Europe and in the Asia Pacific region. In particular, France is still the leading country for IPTV and about 17 % of the French population is presently already using an IPTV service. A typical way to offer IPTV to customers (by Telcos and Internet Service Providers) is to offer this service via DSL. However, also wireless access networks such as Wi-MAX or LTE become increasingly relevant. The transmission of TV programs leads to very large bandwidth requirements within the communication infrastructure if a large number of TV channels (>; 100) has to be offered in parallel and possibly also in high quality (e.g., HDTV quality). Therefore, serious bottlenecks in the communication network may occur which may lead to a temporary unavailability of some of the more unpopular TV channels. The talk summarizes the comprehensive experiences in IPTV research (both for DSL and WiMAX access) within the Telecommunications and Computer Networks Division at University of Hamburg. In particular, emphasis will be given to our recent research results related to new measures (called “multicast gain”), which allow one to quantitatively assess the usage of multicast versus unicast, both, for wired and for wireless links in networks; realistic models to characterize the behaviour of IPTV users; methods to calculate the overhead resulting from multicasting and unicasting TV channels in WiMAX based IPTV systems; a new access control algorithm for TV channels offered via DSL which favours more popular channels as compared to infrequently watched ones and turns out to increase channel availability quite strongly in numerous high-load situations; algorithms to reduce either the channel switching delay or the channel unavailability in IPTV systems with users zapping channels frequently. The research results presented should be a valuable source of information mainly for Internet Service Providers (ISPs) or Telcos offering IPTV services, but also to re-searchers, developers, (post-) graduate students, etc who are interested in the analysis, assessment, tuning, construction and/or installation of efficient and highly available IPTV systems with DSL- or WiMAX-based access networks.