%0 Journal Article
%T Robust IPTV Delivery with Adaptive Rateless Coding over a Mobile WiMAX Channel
%A Laith Al-Jobouri
%A Martin Fleury
%A Mohammad Ghanbari
%J ISRN Communications and Networking
%D 2011
%R 10.5402/2011/481247
%X As intelligent content management of IPTV moves popular material nearer to the end-user, application-layer channel coding schemes, involving the retransmission of extra redundant data, become attractive as a result of the reduced latency. Application-layer, adaptive rateless channel coding is exploited in this paper's scheme to reconstruct streamed video across an IEEE 802.16e (mobile WiMAX) channel. The paper concentrates on the trade-offs in implementing the scheme, showing that exact calculation of the redundant data has the potential to reduce the forward error correction bit-rate overhead. To reduce delay, an appropriate compression rate should also be selected. 1. Introduction The BBC¡¯s iPlayer in the UK [1] has demonstrated the demand for Internet Protocol TV (IPTV) value-added video streaming in the form of content-on-demand and time-shifted TV. However, this service is primarily aimed at asymmetric digital subscriber line (ADSL) receivers and may be ill adapted to mobile wireless broadband delivery. In such broadband wireless networks, including IEEE 802.16e (mobile WiMAX) [2], adverse channel conditions are a concern for video streaming and will become more so as the transition to higher data-rate IEEE 802.16m (WiMAX 2) [3] occurs. The IEEE 802.16e standard provides Turbo coding and hybrid ARQ at the Physical layer with scalable transmission bursts depending on radio frequency (RF) conditions. However, application-layer forward error correction (AL-FEC) [4] is still recommended for IPTV during severe error conditions. This paper demonstrates packet-by-packet adaptive rateless channel coding to guard against burst errors possibly caused by slow and fast fading on a WiMAX channel. The prior IPTV content delivery network (CDN) scheme discussed in [5] was end to end, providing adaptation through a form of FEC simulcast. For severe conditions, it relies on the lower overhead and linear decoding complexity that one form of rateless coding, Raptor codes [6], provides. However, it now seems likely [7] that intelligent content management will result in local caching of frequently requested content. This development enables packet-by-packet adaptive rateless coding, depending on local measurements of channel conditions. Given the reduced latency, it may also be possible to include limited retransmission of extra redundant data, made feasible through rateless channel coding. The iPlayer, as mentioned above, is a simple simulcast service with H.264/AVC (Advanced Video Coding) codec compression [8] and streaming rates available at 500£¿kbps, 800£¿kbps, and
%U http://www.hindawi.com/journals/isrn.communications.networking/2011/481247/