FEC-Based Wireless Video Streaming with Pre-Interleaving

Wireless video streaming is a challenging task due to limited bandwidth and error-prone characteristics of the wireless channels. In order to ensure high quality wireless video streaming, error control techniques such as forward error correction (FEC) is needed. It is well-known that, in mobile radio channels, errors are not limited to single bit errors but tend to occur in bursts. In order to combat with bursty errors, FEC schemes need to be integrated with interleaving so that FEC channel coding capabilities can be fully exploited. For existing FEC-based wireless video streaming systems, channel coding is first applied to the compressed video bitstream. In the case of block channel coding, such as the Reed-Solomon codes, every K source symbols will generate a channel coded block of N symbols. When the block interleaver is adopted, channel blocks of N symbols are loaded into a rectangular matrix row by row. After M rows are collected, which is called the interleaving depth, symbols are read out column by column. This way, interleaving is orthogonal to the channel coding direction and is able to re-distribute bursty errors to many channel blocks within an interleaving matrix. However, such conventional design of FEC-based video streaming may result in significant performance degradation if there are residual errors remaining after the channel decoding. This is because current video coding standards are all block-based and the re-distribution of the errors by interleaving will affect many source blocks if the channel coding cannot generate error-free video bitstream. In this research, we propose a novel robust video streaming system in which an interleaving is applied to the compressed bitstream before the channel coding. The application of this pre-interleaving will be able to improve the performance of wireless video streaming without increasing the system complexity. It is this pre-interleaving that preserves the bursty error patterns in the channel decoded video for an efficient source decoding. However, the orthogonal relationship between channel coding and interleaving remains intact. Therefore, this new scheme is able to facilitate both an efficient channel coding and an efficient source coding for robust wireless video streaming. Experimental results demonstrate that this proposed scheme can achieve great improved performance in wireless video streaming.