A Research On Channel Estimation Of OFDM System Based On OQAM Modulation

With the rapid development of wireless communication technology, the transmission rate,the communication quality and the resource utilization of the wireless communication systemput forward higher requirements. The technology of Orthogonal Frequency DivisionMultiplexing (OFDM) can eliminate the adverse effects caused by multipath fading channeleffectively; it has high spectrum efficiency, and is widely used in the fourth generation mobilecommunication system.In this paper, we point out that cyclic prefix (CP) is needed to eliminate the symbolinterference under the condition of multipath fading channel in traditional OFDM system byanalyzing the traditional OFDM system but the OFDM/OQAM system can eliminate the intersymbol interference generated through a filter group under the multipath fading channelwithout increasing the cyclic prefix, so as to further improve the spectrum efficiency. Afterthat, the performance of CP-OFDM system and OFDM/OQAM system are under differentmodulation methods, and the simulation and verification are processed by emulated andverified by using the MATLAB, OFDM/OQAM system is better than CP-OFDM system isconcluded. The last, it focuses on the channel estimation method for OFDM/OQAM system.The channel estimation method of the traditional CP-OFDM system and OFDM/OQAMsystem are analyzed firstly, and then the defects of OFDM/OQAM system in the channelestimation are pointed out, channel estimation method in OFDM system is improved byanalyzing the disadvantages of the OFDM/OQAM system. And then channel estimationmethod based on the Preamble is studied to eliminate interference. In order to eliminate theinterference of pilots in the system by the method, improve the accuracy of channelestimation, which is obtained by the simulation results, the performance of system can beimproved by a joint iterative channel estimation method based on Preamble which caneliminate interference in channel estimation. We can draw the conclusion through thesimulation results: with the increasing of iterations, the performance of the OFDM/OQAMsystem gradually tend to be ideal under the condition of the channel estimation.