Research On Anti-interference Wireless Ultraviolet Communication Networking Technology

The traditional radio frequency communication will be seriously affected by the enemy's electromagnetic interference in complicated battlefield environment.In this situation,the ultraviolet communication technology can be used for effective communication under strong electromagnetic interference.And in the complex terrain,the ultraviolet communication can be completed by non-line of sight mode,ultraviolet communication has strong terrain adaptability,and its characteristic of omni-directional are also suitable for battlefield environment,so UV communication is an effective supplementary communication means in complex battlefield environment.In order to meet the communication needs of combat teams in the specific environment,and to ensure the reliability of the link,star-shaped network topology structure is given priority as the composition mode of the network.In star network topology,CDMA technology is used to build UV communication network to ensure that users who know the corresponding address code can obtain the corresponding baseband signal by demodulation,which improves the anti-interference performance.Channel coding is also one of the means to improve the anti-interference performance of the system,LDPC code can approach Shannon limit.In this thesis,CDMA technology and LDPC channel coding technology are combined in the ultraviolet communication network,which reduces the bit error rate of the ultraviolet communication system and improves the anti-interference performance of the system.The details are as follows:1.The application of CDMA Technology in UV communication system is studied.The networking form of multi-user UV spread spectrum communication system is given,and this thesis introduces the composition of multi-user CDMA direct sequence spread spectrum ultraviolet communication system.A multi-user CDMA direct sequence spread spectrum ultraviolet communication system is built on the simulation platform,and the BER of the system under different communication schemes is analyzed and compared.The simulation results also show that increasing the order of Walsh code can reduce the bit error rate and improve performance of the system.And the simulation results also prove that the increase of the elevation angle of the transmitter and receiver will lead to the increase of the BER of the system.2.The application of LDPC code in multi-user CDMA UV spread spectrum communication system is studied.The simulation is carried out on the basis of the nonline of sight mode of the UV communication system.BPSK is selected for modulation mode,different parameters in LDPC code are changed,and the BER performance of the system is simulated and analyzed.The simulation results show that after LDPC coding,the bit error rate of the receiver decreases significantly.The decoder adopts soft decision decoding algorithm.The larger the maximum iteration times,the longer the code length,the smaller the code rate,the better the transmission accuracy of the system.3.The basic structure and principle of rake receiver are studied.In the multi-user CDMA direct sequence spread spectrum ultraviolet communication system,the rake receiver technology is applied.The model of the rake receiver is built on the simulation platform.The BER of the system under different communication schemes is analyzed and compared.The simulation results show that the performance of the rake receiver is the best under the maximum ratio combining mode.Increasing the number of taps can also improve the performance of rake receiver.In conclusion,In non-line of sight mode of ultraviolet communication,In starshaped network of combat teams based on class and platoon,the application of CDMA technology and LDPC coding can reduce the bit error rate and improve the antiinterference performance of the UV communication system.