Simulation and Comparison of Channel Estimation Based on Block-type Pilot Frequency in OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) splits a high-speed data stream into a number of lower-speed data streams that are transmitted simultaneously over a number of subcarriers. The capability of resistance of intersymbol interference and bandwidth efficiency are improved, and multipath fading is effectively combated. In order to improve communication efficiency and communication quality, it is necessary to make a dynamic estimation of the current characteristics of the channel. In OFDM system, the technology of channel estimation based on the pilot frequency of block-type distribution is that pilot signal is inserted at regular intervals of time on the transmitting terminal, and on the receiving terminal extract pilot signal from the received data stream, and according to that the channel characteristics are estimated at the period of time. Three common methods of channel estimation based on pilot frequency: MMSE estimation, LS estimation and SVD estimation are discussed with comparison in OFDM system. Through the simulation of matlab, three channel estimation methods and their characteristics are analyzed and compared. The results show that the performance of MMSE estimation is far better than that of the LS estimation, but MMSE estimation has high computational complexity. The performance and computational complexity of SVD estimation are ranged between that of the MMSE estimation and LS estimation.