Space dynamic communication base stations are characterized by high mobility, flexible deployment and wide coverage. It has a wide range of needs in the fields of emergency communication, earthquake relief and island communication. To solve the problem of a limited number of users due to the limited bandwidth of space base stations, so we should improve the reliability and efficiency of data transmission between space mobile base stations. According to the characteristics of the airship platform, a blimp-borne laser communication terminal applied to space dynamic base stations is designed to meet the demand for bi-directional transmission of 5G signal laser carriers in space between airships. The experimental results show that the blimp-borne laser communication terminal achieves an overall technical index of capture probability is better than 98%, the average capture time is 5s, the tracking accuracy is better than 6–15 μrad, the communication rate is 2.5 Gbps and BER is 1E-7. In order to realize the real-time evaluation of the performance of laser communication system under the turbulent channel and guide the research of anti-turbulence fading method, a real-time test method of communication channel turbulence characteristics based on the principle of light intensity scintillation is proposed. And the real-time test of turbulence characteristics of airship inclined link and the horizontal link is completed. The research results play a positive role in promoting the development of 5G mobile technology and space optical communication technology.

An atmospheric turbulence suppression algorithm based on avalanche photodiode adaptive gain control (APDAGC) for the laser transmission terminal was proposed to suppress atmospheric turbulence. The given design mechanism and experimental results demonstrate its function to improve the performance of FSO. When APDAGC is over 1 km FSO, the variance of intensity fluctuation is lowered from 0.046 to 0.009, with the bit error rate reduced from 4.82E-6 to 1E-12. Comparatively, as APDAGC is over 6.5 km FSO, the variance of intensity fluctuation is decreased from 1.767 to 0.376, with the bit error rate varying from 4.6E-2 to 2.4E-4. Moreover, it was used for the first FSO transmission of 5G base station signals on an airship platform.

Space laser communication, with its strong anti-jamming capability, high transmission rate and good adaptability, offers hope for the establishment of 5G mobile networks in areas that are not conducive to the erection of cables, such as islands and remote land areas. Turbulent scintillation effect is one of the important factors affecting the performance of laser communication, which can lead to the increase of communication BER and even communication interruption. Based on the working principle of the photoelectric detector in atmospheric turbulence, an optical communication receiving system based on the detector gain factor regulation control is designed, which calculates the scintillation variance according to the received signal in real time, establishes the function conversion relationship between the scintillation variance and the gain factor, realizes the closed-loop regulation control of the detector gain factor, and improves the SNR of the receiving system. A ground-based 13km static laser communication experiment was set up to test the reception performance, and the test results show that the system reduces the communication BER by more than two orders of magnitude and can be kept at 1E-6 under medium to weak turbulence (discriminated by flash variance) at a communication rate of 2.5Gbps. The technology was applied to the test of laser 5G signal transmission between the airship and the ground, and for the first time, the mobile communication (access network) signal transmission with a downlink speed of 1.230Gbps and an uplink speed of 76.4Mbps is realized, which verified the performance of mobile signal transmission between the mobile base station and the fixed station on the ground.

We experimentally demonstrated a one-to-two-point free-space optical communication (FSO) system based on non-mechanical beam servo device in the laboratory. After the initial pointing, two sets of liquid crystal variable retarder cascaded polarization gratings perform non-mechanical beam servo and realized switching or working simultaneously of two communication links. The non-mechanical beam steerer had four diffraction fields; each can achieve beam steering with a 3.72° field and 30.77 µrad resolution, and the system emission efficiency was higher than 77%. The corresponding switching times of links at 2, 4, and 10 Hz were 46.7, 43.8, and 42.1 ms, respectively. In the quasistatic condition, the sensitivities of the two links under the data rate of 10.3125 Gbps were -23.18 and -23.01 dBm, respectively, indicating the service transmission capability of the multi-node beam control system.

Ocean turbulence is an important factor affecting the development of underwater wireless optical communication (UWOC). To improve the error characteristics of the underwater optical communication system, we propose a differential detection-based multi-receiver-multi-transmitter (MIMO) underwater laser communication transmission method. Additionally, we derive the expressions for calculating the average BER of the MIMO underwater wireless optical communication system with differential detection and non-differential detection in the case that the two transmitted beams are completely uncorrelated. The error characteristics of the MIMO system are simulated and analyzed from the perspective of ocean turbulence intensity and link distance. The simulation results show that the differential detection method has a lower average BER compared to the non-differential detection method in the case of moderate-to-strong ocean turbulence. In addition, the differential detection methods do not have the error floor effect, and non-differential detection methods have the error floor effect. The more the turbulence intensity affects the average BER of the MIMO UWOC system with the increase of the communication link distance, the more obvious is the effect of the turbulence intensity on the average BER of the MIMO UWOC system. Accordingly, the simulation analysis shows that the differential detection method is more suitable for the construction of communication links under long-distance and medium-strong turbulence.