Research On Key Technology Of Channel Coding On Ground Wireless Laser Communication

Wireless laser communication is a way of transmitting data in space using laser beam as carrier.There are three mainly kinds of wireless laser communication,inter-satellite laser communication,satellite to ground laser communication,ground laser communication.Ground laser communication can be used between ground-based buildings or in rivers,lakes,mountains,deserts and other places.In this paper,it mainly refers to Ethernet wireless laser communication between islands.However,when wireless laser signal is transmitted in the atmosphere,it will be affected by various atmospheres and weather conditions,resulting in serious random error and burst error.In order to solve this problem,this paper studied how to improve the error performance of the wireless laser communication between islands in channel coding and FPGA implementionFirst of all,the error characteristics of wireless laser communication system between islands has been qualitatively analyzed.Then an appropriate channel coding scheme was designed according to the error characteristics and error control methods,and an appropriate correction code was selected.Secondly,the characteristics of the selected low density parity check code?LDPC?were studied and a suitable coding method is selected.By comparing the performance and complexity of several different decoding algorithms,the improved min-sum algorithm was selected as the LDPC decoding algorithm to reduce the error rate from10^-3 to less than 10^-6.For the burst error whose length is less than 1 ms,an interleaver with adjustable parameters has been designed,and its performance was analyzed.The channel coding designed in this paper was composed of LDPC code and interleaver.Then,the channel coding system which can be used for Gigabit Ethernet communication was designed.The architecture design and FPGA implementation of all modules including,All modules in this system including LDPC encoding,decoding and interleaving modules were designed and implemented in FPGA,and the functions of each module and the whole system were verified by functional simulation in FPGA.Finally,to test the system implemented in FPGA,a variety of work modes,random error and burst error conditions has been designed,then a point-to-point Ethernet communication test system which was constructed by hardware platforms,switches,and personal computer?PC?was designed to test and verify the actual decoding performance of the LDPC code,the point-to-point system's communication speed,rate of packet loss,and the performance against burst error.The test results showed that the channel coding system designed in this paper meets the requirements of random error code and burst error.The result of the research in this paper can support Gigabit Ethernet communication,proving its engineering value.