Reliable ATM transmission of multimedia in wireless networks

We described the error-control problems associated with supporting ATM transmission of multimedia services on line of sight (LOS) radio circuits. The major problems to address are associated with poor circuit quality and limited transmission bandwidths. Poor circuit quality is manifested by low received SNRs and high delivered BERs and can be improved by judicious application of error-control coding. The desire to support as many ATM users as possible and the constraint of limited bandwidth favor the use of high-rate coding techniques. To provide an acceptable QoS, however, the selected coding technique must be effective for all realistic channel conditions, including AWGN and slow Rician fading. It was shown that binary BCH codes can be used to provide a highly effective error-control technique for ATM transmission on LOS circuits. The wide selection of block lengths, rate, and error correction power allows solutions to be tailored to the wireless ATM application. It was shown that the best designs result when a powerful binary BCH code is used to protect the header and a somewhat less powerful code is used to protect the payload. The effects of residual uncorrected error events can then be addressed with an appropriate end-to-end error-control technique, or, in the case of MPEG video, with error concealment algorithms. It was also shown that Reed Solomon codes with erasure filling can provide an effective, high-rate, end-to-end coding scheme to protect against cell loss due to congestion in ATM networks and decoding failure events associated with the link codes