Research And Simulation Of Power Control Algorithm For Satellite Mobile Communication System

Uplink power control technology is an important technology in the radio resource management of satellite mobile communication systems.On the one hand,because the channel transmission loss is large,sufficient transmission power is needed to ensure the signal transmission quality.On the other hand,the terminal needs to save power resources.It is easy to cause intermodulation interference of the satellite traveling wave tube amplifier with too strong total uplink power.The CDMA technology which has the characteristics of anti-interference and high rate characteristics is very suitable for China's next-generation satellite communication system,and power control can effectively suppress the multiple access interference in CDMA system.So this thesis focuses on the uplink power control algorithm for satellite mobile communication system with CDMA.This thesis first briefly introduces the architecture of the satellite mobile communication system and analyzes the purpose and criteria of the implementation of the power control technology in the CDMA system,and then theoretically analyzes the classical distributed power control algorithm.In addition,this thesis analyzes the cost function of Koskie algorithm and NPCG algorithm based on the non-cooperative game theory.The former has low power consumption but it is difficult to meet the target signalto-interference ratio.The latter is just the opposite.Based on the signal-to-interference ratio criterion,this thesis proposes a power control algorithm named as A-NCPCG based on the non-cooperative game theory and link prediction.The algorithm redesigns the cost function with the goal of low satellite receiving power on the condition of meeting the target signal-to-interference ratio.In order to reduce the lag effect of the satellite long delay channel,an autoregressive integrated moving average model is introduced to predict the link quality in the iterative process of the algorithm to achieve the purpose of delay compensation.Besides,the advantages of this algorithm over classical algorithms are analyzed,and the existence and convergence of the Nash equilibrium of the algorithm are proved.The simulation results show that when 20 terminals are 20km/h,the A-NCPCG algorithm has lower control error and power consumption in low-speed mobile terminals,and the probabilities of 1dB signal-to-interference ratio error and 2dB signal-to-interference ratio error are reduced by 19% and 11% respectively.The total uplink power is reduced by 1dBW.At the same time,from the perspective of engineering application,this thesis designs and implements a satellite mobile communication power control system simulation platform based on OPNET software.The simulation platform has code division multiple access physical channel,basic signaling interaction process and power control command generation or processing.In this thesis,the quantization method and processing method of power control commands are designed in detail,and implemented in the form of nodes and processes.Based on the simulation platform,a set of optimal parameters are found for the engineering implementation of A-NCPCG algorithm.The simulation results show that the system has optimal performance when the power control command is quantized to 0.5dB,1.5dB,the preprocessing coefficient is 0.4,and the outer loop power control step is +2.5dB,-0.5dB.