Link reliability, range and rate optimization for free-space optical channels

Rate maximization and link reliability versus range tradeoff optimization for uncoded free-space optical (FSO) communication links in the presence of atmospheric turbulence and misalignment are analyzed via beam width selection. Two strategies are considered for beam width selection: adaptive and fixed beam width. The choice among these strategies depends on system performance and complexity. Performance evaluations and comparisons are conducted using both on-off keying (OOK) and pulse position modulations (PPM). Different weather conditions are considered. It is shown that employing a properly designed fixed beam width results in a small performance degradation with substantial reduction in system complexity compared to adaptive beam width strategy.