Performance investigation of multi-aperture digital combining algorithm for satellite-to-ground coherent optical communication

Abstract

An important component of the future communication network will include satellite-to-ground communication technology. In the meantime, the community of communication network also has a huge capacity as one of its purposes. In this situation, the free-space optical (FSO) communication technology is a potential option for satellite-to-ground communications. A major drawback of FSO communication systems, nevertheless, is atmospheric turbulence. Multi-aperture receiver with digital combining architecture is an effective approach to overcoming the effect of atmospheric turbulence on the performance of free-space optical (FSO) communication. In this paper, a blind digital combining algorithm for coherent FSO communication is proposed. To verify the effectiveness of the proposed combining algorithm, a 10-Gbps data rate single polarization 16-ary quadrature amplitude modulation (SP-16QAM) offline four-aperture simulated turbulence experiment is performed, and the performance of multi-aperture spatial diversity and signal processing is emulated through the experimental data. The results confirm that the proposed blind digital combining algorithm has an excellent performance in average bit error rate (BER). Compared with the single-aperture system, the receiver sensitivity of the four-aperture is increased by 1.2, 4.6, and 6.8 dB for the cases of weak, moderate, and strong turbulence at the SD-FEC threshold, respectively.