Bit-loading for unequal error protection of video streams in OFDM wireless systems

Future wireless video transmission systems would consider OFDM (orthogonal frequency division multiplexing) as basic modulation technique due to its robustness and low complexity implementation in the presence of frequency selective channels. Recently, adaptive bit loading techniques have been applied to OFDM showing good performance gains in cable transmission systems. In this paper adaptive loading techniques are applied to an OFDM wireless system in the 5 GHz band for efficient layered multimedia traffic transmission. A low complexity scheme is introduced and compared with other solutions to realize unequal error protection both at coding and modulation level. The large impact of this technique in terms of video quality is evaluated for MPEG-4 video transmission.