Raptor-network coding strategies for energy efficient cooperative DVB-H multimedia communications

Reliable and energy-efficient delivery of mobile multimedia across different platforms and application scenarios is very challenging. Both open and proprietary standards exist worldwide; we focus on enhancements to the digital video broadcasting - handheld (DVB-H) standard for transmission over cooperative cellular networks, which enables the use of relaying to supplement existing fixed infrastructure. Cooperation creates a distributed form of multi-input-multi-output (MIMO) systems, resulting in breakthroughs in network energy efficiency and reliability. Thus, cooperative networks have an inherently green ad hoc topology that is able to substantially reduce infrastructure cost, system complexity and energy expenditure. In this paper, novel strategies are proposed and evaluated that combine: (1) fountain coding, e.g., Raptor codes at the application layer, and (2) network coding. Originally proposed for broadcasting over the Internet, the application of fountain codes to wireless cooperative communications networks has been limited to date. These codes enable lower (physical) layer compatibility. Network coding is used to reduce energy consumption by opportunistically recombining and rebroadcasting required combinations of packets. The energy cost of our peer-to-peer file repair sessions, which are integrated with the file delivery session itself, are quantified. Signal processing and modeling techniques used for cross-layer system simulations are also overviewed.