Research And Application On CoMP-JP Technology Of LTE-Advanced System

In order to improve communication performance of cell edge users, CoMP(Coordinated Multiple Points Transmission/Reception) technology is proposed. CoMP technology contains two special cases:CoMP-JP(Joint Process) and CS/CB(Coordinated Scheduling/Coordinated Beamforming).In this thesis,we focus on CoMP-JP technology. CoMP-JP technology can effectively improve the communication quality of cell-edge users, promote fairness among users within a cell. However, CoMP-JP technology has both advantages and disadvantages, the cooperative base stations need to exchange information with each other, adds extra system consumption.This thesis studies the division of cooperative area and non-cooperative area within a cell and the energy efficiency of CoMP-JP.Then the CoMP-JP technology researched in this thesis is applied in high-speed railway mobile communications and heterogeneous networks communication respectively. The main contents of this thesis can be summarized as follows:1. Firstly, we assume the cell is arranged linearly, then the division of cooperative area and noncooperative area within a cell is studied. Considering three cells arranged linearly, the utility function of divide-radius is proposed to evaluate the advantages and disadvantages of CoMP-JP technology. Then, an optimized model of CoMP-JP utility function is derived. This chapter considers two user distribution: Uniform distribution and Gaussian distribution. For these different user distribution, the relationship between the utility function and divide-radius is analyzed and the existence of the optimal solution is proved respectively. Then we proposed an iterative algorithm to find the optimal solution. Finally, numerical results demonstrate the relationship between the utility function and divide-radius. We can get a conclusion that when user distribution is Gaussian distribution, the unit change of divideradius has a more impact on CoMP performance than uniform distribution.2. Energy efficiency of CoMP-JP technology is studied in this thesis. We assume that a multiuser cell is surrounded by a plurality of base stations and these base stations can participate in cooperative communication, then an energy efficiency optimization problem of CoMP-JP is established. Firstly, the energy efficiency without CoM-JP technology is analyzed and the conclusion that the energy efficiency has an inversely proportional relationship with the number of adjacent base stations is given. Then, the energy efficiency with CoM-JP technology is analyzed and the optimization problem of energy efficiency with cooperative BSs’(base stations) number is proposed. The relationship between energy efficiency and the number of cooperative base stations is analyzed and the algorithms to find the optimal number of cooperating base station and the optimal divideradius are proposed respectively. Simulation results show that reasonable cooperative BSs’ number can improve the energy efficiency of the system and the energy efficiency has a certain relationship with the divide-radius.3. CoMP-JP technology applied to high-speed railway communication is researched in this thesis. The problem of handover and Doppler Shift seriously affect the performance of high-speed rail communications. Firstly, a CoMP utility function of the maximum adjacent cell overlap is proposed. Theoretical analysis show that there exists an optimal value of this maximum overlap distance and the system can achieve the best overall performance when using this optimal value in high-speed rail communication.An algorithm to find the optimal maximum overlap distance is proposed. In addition, this chapter also proposed an algorithm based on CoMP-JP technology to estimate the doppler shift in high-speed railway communication. Simulation results show that CoMP-JP technology applied to high-speed railway communication can improve the capacity of the cell and reduce the error rate effectively.4. CoMP-JP technology applied to heterogeneous network is researched in this thesis.Several different types of base stations often existed in a heterogeneous network and the power of these different types of base stations are different. We assume that one macro base station and a number of Pico base stations are located in one cell and Macro base station and Pico base station transmit data cooperatively. According to the theoretical research above, An model of energy efficiency with the number of Pico base stations is built. Simulation results show that when the number of Pico base stations is smaller than a threshold located in one cell, energy efficiency increases with the increasing of the number of Pico base stations and when it exceeds the threshold, energy efficiency decreases with the increasing of the number of cooperative BSs. By optimizing the number of Pico base stations, energy efficiency of heterogeneous network can be improved.