Research On Concatenated Coding Technology Based On Visible Light Communication

Communication technology is an essential component of human technological advancements,playing a significant role in human development and progress.With the rapid advancement of communication technology,the expansion of 5G communication and the application of Io T（Internet of Things）technology have emerged.People’s demand for communication services,such as mobile and internet connectivity,has transitioned from initially having access to services to seeking higher service quality.However,the growing demand has exacerbated the scarcity of wireless spectrum resources.Visible Light Communication（VLC）,as an emerging technology that combines illumination and communication,offers a wider spectrum and higher transmission rates.It can alleviate the strain on spectrum resources and is considered a technology core for future applications such as optical networking and 6G communication networks,potentially replacing RF（Radio Frequency）technology.VLC has significant research value and vast development prospects.Due to the current immaturity of VLC（Visible Light Communication）technology,there is still extensive exploration space for addressing issues such as noise generated within devices and mixed errors during the optical transmission process.Channel coding techniques can effectively improve the interference resistance of communication systems without increasing bandwidth.Polar codes,as the only channel coding method that approaches the Shannon limit,have been widely adopted in communication scenarios with large data volume,high-speed transmission,and complex environments,such as 5G e MBB,Wi Fi 6E,and satellite communications.Introducing Polar codes into VLC systems can significantly enhance system reliability.However,the error correction performance of Polar codes is constrained by the code length,and excessively long codewords increase system complexity.Therefore,a concatenated approach is employed by serially concatenating short Polar codes to construct concatenated codes,enabling iterative decoding to enhance the error correction capability of individual codewords and improve system decoding efficiency.This thesis uses polar codes as constituent codes and designs a concatenated polar code scheme to improve error transmission in VLC systems,increase system reliability,and further promote the development of VLC.The main research contents and innovative achievements are as follows:（1）Introduction to the basic architecture of indoor visible light communication system is analyzed,and the optical characteristics of white light LED light source and photodetector are expounded.An indoor optical transmission channel model is established,and the light received power at different positions and the bit error rate curve of the VLC system without a coding scheme are simulated and analyzed.（2）In-depth study of the principles of polar code encoding and simulation of the decoding performance of polar code under different parameters and decoding algorithms in VLC channels.A pruning-based improved SCL decoding algorithm is proposed,and simulations show that the improved decoding algorithm reduces the decoding complexity by over 45%compared with the unimproved method.The error rate performance curve shows that the decoding performance has no significant loss and gradually approaches as the channel conditions improve.（3）Based on the improved Polar decoding algorithm,a combined coding scheme is proposed,where RS and BCH codes are used as outer codes and Polar codes are used as inner codes.The information sequence is supplemented with CRC check bits.Two interleaving concatenated codes schemes are designed,namely block and random interleaving.Compared to the popular LDPC-Polar concatenated scheme,the proposed scheme exhibits lower decoding latency and comparable decoding performance with a target bit error rate of 10^-6.Under the same code rate,the interleaving concatenated schemes show improved error performance in handling mixed errors in VLC systems compared to the single-level concatenated scheme with CRC check for（256,64）Polar code.The BCH-BI-Polar scheme performs better in poor channel environments,achieving a 29%reduction in bit error rate,while the RS-BI-Polar scheme converges faster in better channel conditions,providing a coding gain of 0.8 d B.