Performance analysis of optical differential spatial modulation over atmospheric joint effect

Traditional optical spatial modulation techniques all rely on the premise that the system receiving end can obtain accurate channel state information.The optical differential spatial modulation (ODSM) system effectively avoids complex channel estimation, but related research only analyzes the system performance under a single turbulent state, and ignores the effects of factors such as pointing errors and path loss in actual free space optical communication systems.Therefore, the Málaga turbulence channel, which could characterize all atmospheric turbulence states, was used to derive the upper bound expression and diversity order of the bit error rate of the ODSM system under the atmospheric joint effect such as turbulence, pointing error, and path loss.The analysis results show that compared with other optical spatial modulation schemes, the ODSM system avoids complex channel estimation, making the system no longer affected by channel estimation errors, thus possessing higher anti-interference and stability.The bit error rate performance of the ODSM system decreases as the intensity of turbulence and pointing error increase.By optimizing parameters such as the number of optical antennas, the number of photodetectors, and the modulation signal order, the bit error rate performance of the ODSM system can be further improved.