Interleaving to mitigate burst errors due to dynamic pointing and tracking losses

Scintillation mitigation is a key aspect of communication performance for lasercom links. Scintillation is most often associated with turbulent channels but can also be caused by residual pointing and tracking dynamics. In high-performance terminals on quiet platforms, robust line-of-sight stabilization can minimize jitter to a small fraction of a beamwidth, so that fading due to pointing and tracking is small enough to be compensated with link margin. However, scintillation mitigation techniques can potentially enable lower cost terminal designs and facilitate hosts with larger base disturbances. Here, we investigate the use of interleaving to mitigate fading induced by pointing and tracking losses. Interleaving scrambles bits in a deterministic fashion so that entire code words are not lost during an individual fade. While introducing latency and additional digital buffering requirements, interleaving also enables forward error correction to function in channels where the coherence time is long compared to the duration of a code word. We consider various jitter characteristics and beam profiles to generate different pointing and tracking loss time series. We then use these fading channels in bit-level communication performance simulations to determine the average power and capacity penalties for operation in a specific fading channel. The results can guide system designers in selecting when interleaving is an appropriate tool for mitigating pointing and tracking dynamics in a lasercom link.