Lte System Simulation Platform Building And Location Technology Research

With the development of communication technology, LTE has been deployed in Sweden, the United States and other countries. In China, LTE has also been put into test in many cities. This makes the optimization of LTE system become the research focus. In addition, LBS(Location Based Services) is playing a more and more important role in people’s life, but the signal transmission in wireless channel will be affected by the NLOS, multi-path effect, etc, which leads to lower position precision. In order to meet the needs of LBS, high precision and low complexity positioning technology is also become the object of scientific research department. Therefore, this paper will research the optimization of LTE downlink and its positioning technology based on the simulation platform of LTE system.First, this paper shows the theory of several basic localization algorithms, and does simulation contrast in the environment of white gaussian noise channel and the NLOS channel respectively. Then, the paper shows the OFDM key technology of LTE downlink and the channel estimation technology according to the characteristics of LTE, and realizes two kinds of LTE downlink optimization research based on this, which are the energy consumption optimization research corresponding the transmission block size and the joint optimization research of HARQ process and channel decoding process, and gets the ideal results through the simulation.Then, based on the characteristics of LTE signal, the paper proposes one kind of TDOA location method based on the frequency domain correlation time estimation algorithm, and introduces an interference elimination technology to improve the TDOA location performance, and finally, mobile terminal position coordinates are estimated using WLS. Through the NLOS simulation, we compare this algorithm with time domain correlation localization algorithm, the result shows the proposed method can provide higher accuracy, and can effectively improve the positioning accuracy on the edge of cell.This paper researches the hybrid positioning technologies of LTE system, and proposes a positioning method which is based on a single base station, and it is a kind of TOA/AOA hybrid positioning method through a mobile terminalwhose location information which is known in the service cell.This method can effectively overcome the influence of the near-far effect which exists in the methods based on multi base stations.At the same time,the paper eliminates the NLOS error of the TOA measurement using the fitting method, and proposes a method of using the AOA information subtly. The simulation results show that this method can effectively overcome the near-far effect, NLOS error, and can reduce the sensitivity to the AOA measurement error. The positioning performance is improved significantly with the guarantee that the algorithm is simple and reliable.