3G 네트워크에서 MPEG-4 스케일러블 비디오의 실시간 방송을 위한 실행시간 예측 기반 MAC계층 오류제어

초록

We analyze the execution time of Reed-Solomon coding, which is the MAC-layer forward errorcorrection scheme used in CDMA2000 1xEV-DO broadcast services, under different air channel conditions. The results show that the time constraints of MPEG-4 cannot be guaranteed byReed-Solomon decoding when the packet loss rate (PLR) is high, due to its long computation timeon current hardware. To alleviate this problem, we propose three error control schemes. Our staticscheme bypasses Reed-Solomon decoding at the mobile node to satisfy the MPEG-4 time constraintwhen the PLR exceeds a given boundary. Second, dynamic scheme corrects errors in a best-effortmanner within the time constraint, instead of giving up altogether when the PLR is high; thisachieves a further quality improvement. The third, video-aware dynamic scheme fixes errors in asimilar way to the dynamic scheme, but in a priority-driven manner which makes the video appearsmoother. Extensive simulation results show the effectiveness of our schemes compared to theoriginal FEC scheme.

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