Research On Technology Of Polar Coding And Decoding Over Ultraviolet Communications

Optical wireless communication(OWC)is a cross integrated communication technology of optical communication and wireless communication.It uses light wave as information carrier and transmits information in free space.It has large bandwidth,no need to apply for spectrum authorization,no conventional electromagnetic radiation,anti-electromagnetic interference,and so on.The advantages have gained more and more attention from researchers at home and abroad.In OWC,ultraviolet communication(UVC)is widely used in military field due of its good concealment,strong anti-jamming ability and no strict alignment.As for the unneglectable influence of path loss over UVC system,this paper makes further optimization on the basis of UVC-relevant polar coding scheme,aiming at making full use of channel polarization,to resist path loss,further improve the system error performance and extend the effective communication distance with computational complexity as lower as possible.The main work done and innovations of this paper are as follows:The characteristics of the ultraviolet channel are analyzed,and the application scenarios of the polar code correlation research in this paper are limited;A path loss particle model considering wave-particle duality is introduced,and the effect of path loss on UVC system is analyzed,and more accurate channel parameters are provided for UV-based polar coding scheme.As for the performance limitation of successive cancellation(SC)decoding scheme under medium and short code length,a parallel successive cancellation list(SCL)decoding scheme for UVC is proposed.The optimized scheme allows multiple decoding paths to be preserved simultaneously in the decoding process,thus reducing the probability of losing the correct decoding path.In addition,cyclic redundancy check is further introduced into the optimization scheme.The simulation results show that SCL decoder can effectively improve the decoding performance,and the performance improvement is positively correlated with the number of reserved decoding paths within a certain range.To solve the problem of computational complexity and storage space occupancy caused by decoding optimization,a low-complexity successive cancellation stack(SCS)decoding scheme and a path deletion algorithm for UVC are proposed.The former introduces depth-first search,which improves the flexibility of decoding path search,while the latter realizes the mechanism of deleting over-error decoding paths at any time in the decoding process.The simulation results show that both of them can effectively reduce the computational complexity while guaranteeing the communication quality.