Research On Power Allocation And Detection Algorithm Of PD-NOMA-VLC System

The next generation of wireless communication involves three density requirements,namely high user density,high traffic density,and dense access point deployment.As an emerging technology,VLC is expected to solve the problem of tight spectrum resources in traditional wireless frequency bands;PD-NOMA technology as a A new type of multiple access technology can achieve a balance between throughput and fairness.This article mainly studies the application of PD-NOMA technology in indoor visible light communication,specifically focusing on four issues:?.Research on the user grouping problem of downlink of multi-carrier PD-NOMAVLC system.First,a system model is given based on the DCO-OFDM-VLC system.The NOMA cluster to which the user belongs is defined by a variable matrix.Each NOMA cluster occupies symmetric subcarriers,and the user reachability and rate after user grouping are optimized.Considering the complexity of the combination problem,the K-means clustering algorithm in data mining is introduced,by limiting the NOMA cluster to which the user belongs,and simplifying the original optimization problem under the determined power allocation scheme.Finally,the value selection problem that restricts one of the performance of the K-means clustering algorithm is improved.The simulation results show that the improved K-means clustering algorithm has a certain system and rate compared with the traditional K-means clustering algorithm and the traditional user matching scheme.?.The joint optimization problem of uplink user grouping and power allocation in the multi-carrier PD-NOMA-VLC system is studied.Based on the previous problem,an optimization variable of user power allocation factor is introduced to jointly optimize the user reachability and rate after user grouping and power allocation.Using the improved Kmeans clustering algorithm proposed in the previous research question to fix users into groups,the optimization problem is reduced to the problem of maximizing the user reachability and rate of a single NOMA cluster.Solve.Finally,the simulation results show that the combined optimization and rate performance are better than those for power optimization only or the improved K-means clustering algorithm.?.The downlink detection algorithm of the multi-carrier PD-NOMA-VLC system is studied.Multi-user detection technologies such as serial interference cancellation are used to cancel user interference at the receiving end,but the problem of error propagation due to serial interference cancellation has not been resolved,reducing the performance of the system's bit error rate and resulting in the inability to ensure user fairness.This paper proposes a joint modulation suitable for scenarios with fewer user multiplexes.Without the need for serial interference cancellation,the log-likelihood ratio of user signal bits can be directly calculated from the joint constellation diagram and the LLR The value is used as the input of the decoder,and the user signal can be detected by channel decoding.Finally,simulations show that the system's bit error rate performance is better than the linear detection and serial interference cancellation detection algorithms under the joint modulation scheme.