Pilot-aided Channel Estimation Technique And Simulation For Multi-Carrier System

With the large-scale promotion of 4G technology, 5G technology has not yet had a unified standard. The major colleges and universities, research institutions, and so on put their effort on the new technology. Compared to the traditional OFDM system, the index modulation(IM) system has become one of the hot research topics in recent years, with anti inter-carrier interference(anti-ICI) and better energy efficiency, lower bit error rate(BER) when interleaved, more flexible configuration advantages. Therefore, it has drawn widespread attention from related international teams.This paper is based on pilot-aided channel estimation technology in traditional OFDM system, which is developed in the index modulation system. A special pilot placement mode is proposed in order not to occupy additional spectrum resource. Then the receiver is designed and optimized, and a variety of pilot detection algorithms and a variety of improved channel estimation algorithm are presented. In the end, this special pilot placement mode in the index modulation system is advanced in multi-antenna technology with proposed pilot placement modes and channel estimation algorithms.The first chapter of the paper reviews the development and research status of OFDM system, IM system, multi-input multi-output(MIMO) system, spatial modulation(SM) system and pilot-aided channel estimation technique.The second chapter introduces three common pilot placement methods and 4 common channel estimation methods in the traditional OFDM system. The differences between different pilot placement methods and different channel estimation methods are compared by simulation. Afterwards, OFDM-IM system pilot placement mode, as well as the basic idea of the receiver design are introduced. At last, the existing problems of the pilot placement mode in OFDM-IM are analyzed by simulation.In the third chapter, based on the analysis in the second chapter, the design of the receiver in the OFDM-IM system is optimized. Then, according to the limitation of the energy detection(ED) algorithm for the pilot position, 3 better pilot detection algorithm are given. The performance and the complexity of each algorithms are compared by the simulation results and analysis respectively. At last, an improved channel estimation algorithm with low complexity is presented. In order to improve the performance of the channel estimation, two joint channel estimation methods by using multiple symbols are proposed.In the fourth chapter, the principle of pilot-aided channel estimation in MIMOOFDM system is introduced, and two pilot placement methods and the corresponding channel estimation methods are introduced. After that, OFDM-IM system is extended to MIMO system and SM system. According to the characteristics of these two system, the pilot placement modes are designed, as well as pilot detection methods and channel estimation method.The last chapter summarizes the whole work of this paper, and introduces the possible future research directions.