Mobile data broadcasting over MBMS tradeoffs in forward error correction

Abstract

Third Generation Partnership Project (3GPP) and Digital Video Broadcasting (DVB) have just recently specified the use Raptor codes in their mobile broadcast file delivery engine. Until today, investigations of the applicability of these codes to the mentioned systems have been carried out by assuming almost exclusively quite simple loss models such as statistically independent radio packet losses. Furthermore, the combination and tradeoffs between physical layer parameters such as transmit power or physical layer for-ward error correction code rates in system design has been completely ignored. In this work we investigate the end-to-end system performance by analyzing the trade-off between physical layer parameters and application layer code. In particular we are interested in determining the optimal system operating points for optimized broadcast file delivery. Parameters such as power allocation, mobility model, physical layer Turbo code rate, raptor code expansion ratio are investigated and a single performance criteria is defined, namely the required energy to deliver a file to at least some high percentage of users. It is shown that typically considered system configurations with high transmit power and low physical layer code rates - resulting in low radio block loss rates - are in general suboptimal for efficient delivery. A careful tradeoff the system parameters can reduce the required resources in the order of a magnitude.