Bit Error Rate Performance of a Laser Ground-to-Satellite Uplink Communications Systems in the Presence of Atmospheric Turbulence and Loss

Abstract

The Bit Error Rate (BER) performance of a ground-to-space laser uplink communications systems subject to atmospheric turbulence and loss is analyzed. Beam wander-induced effects like scintillation and receiver noise variance have a greater effects on communications system performance than has previously been assessed. A new model for the signal-to-noise ratio is presented that includes atmospheric loss, intensity fluctuations, beam wander, and intensity noise variance. This model easily can be modified to other communications systems, e.g., Differential Phase Shift Key. The scintillation index and the BER hence readily evaluated with Forward Error Coding (FEC) to compensate for atmospheric turbulence effects. Specifically, comparisons in 10–12 BER performance for 10 Gigabit per second, Non-Return to Zero On-Off Key, Erbium-Doped-Fiber Amplifier communications systems as a function of link zenith angle are given for the Hufnagle-Valley 5/7 and Hufnagle-Andrews-Phillips refractive index structure parameter models under two specifics benchmarks. These models were evaluated using a round-earth model. These models essentially are commensurate with the multiplicative version of the Hufnagel-Valley 5/7 model, which appears to the more realistic way of model comparison. Results show that in this last situation, BER performance has an asymptotic limit for high zenith angles. The conclusion is that other means in addition to a FEC are needed to achieve a 10–12 BER for high zenith angle. Example is given that shows an approach for augmenting a FEC in mitigating turbulence