Data Combining Schemes for a Detector Array Receiver in Free-Space Optical Communications

An array of detectors is widely used in deep space optical communications for both fine beam tracking and symbol detection. In this paper, we have analyzed and compared the performance of different combining schemes—such as
equal gain combiner
(EGC),
selection combiner
(SC) and the
maximal ratio combiner
(MRC)—that are used to fuse the outputs from the elements of such arrays. The three combining schemes are compared in terms of error rate performance and computational complexity. Additionally, for the limiting case of continuous arrays of circular configuration, the optimization of two important parameters—the spot size and the array size—is also discussed in order to achieve the best error rate performance.