Transport of MPEG2 video and associated audio and data over ATM (asynchronous transfer mode) networks has attracted much interest. A defined MPEG2 transport packet of 188 bytes can fit into 4 ATM cells with 32 bits left for forward error correction (FEC) codes and cell sequence numbers. The author discusses the design of FECs to correct the error patterns generated by different scrambler and line codes used by several ATM physical layers. By choosing generator polynomials carefully, a single-error-correcting Reed-Solomon code can correct not only the single-byte error patterns but also the double-byte error patterns processed by a scrambler. A method of distributing 16 bits of FEC into 4 ATM cells (thus, 4 bits of FEC each cell) to accommodate a cell sequence number in each cell is also given.
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