Link enhancement for ATM over satellite links

The burst errors experienced on coded satellite links impact the operation of both asynchronous transfer mode (ATM) and ATM adaptation layer (AAL) protocols and their transport in synchronous digital hierarchy/plesiochronous digital hierarchy (SDH/PDH) frames. COMSAT has developed an ATM link enhancer (ALE), which provides significant improvement in the probability of cell discard due to header errors, improves loss of frame performance when using the physical layer convergence protocol (PLCP) in PDH, and reduces certain errors experienced in AAL type 1 and AAL type 3/4. This paper describes the DS-3 hardware implementation of the ALE, including the techniques used to establish and maintain the PLCP and deinterleaver frame synchronization, perform selective interleaving/deinterleaving of ATM cells, and perform header error correction on deinterleaved cells. In addition, it provides a functional description of the ALE and the prototype ALE hardware implementation. The paper summarizes the measured ALE performance in a satellite field trial, and compares its measured and predicted performance using data collected via the field trial.<
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