Research On Nonlinear Equalization Algorithm In Wireless UV Communication

The advantages of wireless ultraviolet communication are benefited from the strong scattering of ultraviolet transmission in the atmosphere,but multipath scattering transmission will cause inter-symbol interference.The equalization technology is to adjust and compensate the received signals by inserting a tunable filter in the receiving end,so as to reduce the effect of inter-symbol interference.In the wireless ultraviolet communication system,the equalizer is added to the receiver to compensate the ultraviolet distortion signal through the atmospheric scattering channel,and suppress the inter-symbol interference in the communication.In this paper,the characteristics of several nonlinear equalization algorithrms in wireless ultraviolet communication are mainly studied,a delay decision maximmm likelihood sequence estimation algorithm(TD-MLSE)based on channel estimation is proposed for ultraviolet(UV)communication.The specific research content of the subj ect includes the following points:(1)The application of two nonlinear decision feedback equalization algorithms with minimum mean square error(LMS)and least square(RLS)in wireless ultraviolet communicat:ion system is studied.The key factors affecting the convergence and stability of the algorithm are introduced,the influence of these factors on UV communication is simulated and analyzed,and compare the performance of the two algorithms in UV communication.The simulation results show that the optimal step size of LMS algorithm is near 0,06 in UV communication,and the best forgetting factor of RLS algorithm is 1,Compared with the LMS algorithm,the RLS algorithm has higher convergence speed,stability and equalization perfommance.Compared with the non equilibrium algoritlhn,?when the SNR is 18dB3 and the error rate reaches 10-3,the RLS algoritlhm improves the maximum communication distance of 150m and increases the communication rate obviously.(2)In order to further improve the performance of UV communication,the nonlinear optimal equalization algorithm based on maximum likelihood sequence detection is studied.In order to solve the problem that the original algorithm has too much delay,a TD-MLSE equalization algorithm based on channel estimation is proposed.The simulation results show that the optimal delay depth of the improved algorithm is 20.The improved algorithm improves the communication distance and communication rate of ultraviolet communication.When the signal to noise ratio(SNR)is 16dB,the bit error rate 10-3 is the limit condition of communication,the communication distance can be raised to 700m,the maximum communication rate can reach 3Mbps.The performance is far better than the RLS equalization algorithm,which is very suitable for ultraviolet communication.To sum up,the nonlinear equalization algorithm can effectively improve the performance of UV communication.By analyzing the influence of the algorithm parameters on the equilibrium performance in UV communication,it helps to select the reasonable equilibrium parameter in the design of equalizer;The influence of different algorithms on the performance of ultraviolet communication is compared and analyzed to help select the appropriate equalization algorithm in different communication scene.