Extending Service Coverage Using FGS-Aware Blind Repetition

Frequent bursts of errors are an unavoidable characteristic of the reception at mobile devices, but one which must be dealt with effectively in the provision of broadcast transmissions. The third generation partnership project 2 (3GPP2) broadcast and multicast services (BCMCS) employ forward error correction by Reed-Solomon coding with appropriate interleaving in the MAC layer. But the performance of this method of error recovery degrades significantly at the edge of coverage where the channel conditions are bad, and this leads mobiles to experience a relatively high error rate and long error bursts, which limits the service area of the application. We propose a blind repetition scheme to widen the service area. It retransmits the packets that are most important for video decoding, based on the layered structure of MPEG-4 FGS (fine granularity scalability). This allows improved video quality at edge nodes and effectively extends the coverage. Extensive simulation results show that our scheme safeguards the important packets effectively and improves the video quality, greatly outweighing a marginal increase in the overall error rate. Energy consumption measurements made using the SNU (Seoul National University) energy explorer also suggest that our scheme is more energy-efficient than Reed-Solomon coding alone.