The Study Of Frequency Domain Equalization For Next Generation Mobile Communication System

Orthogonal Frequency Division Multiplexing(OFDM) and Single Carrier Frequency Domain Equalization (SC-FDE) are the fourth-generation mobile communication system's core technologies. OFDM system is different from the traditional multi-carrier modulation technique. For the orthogonality , OFDM's various sub-carrier spectrum can be superimposed, so OFDM can fully use spectrum resources and effectively combat multipath propagation which causes inter-symbol interference (ISI).As for the Single-carrier frequency domain equalization (SC-FDE) technology, the receiver using FFT transform blocks to handle data, the complexity is lower than traditional single-carrier time-domain equalization technique. To further improve system performance, especially in the larger Doppler frequency shift system, OFDM systems and SC-FDE systems have many key technologies needing solution. The channel frequency-domain equalization is one of them.In this paper, frequency-domain equalization technique of OFDM and SC-FDE system are mainly studied. The completed tasks are as follows.At first, the basic principles, mathematical expression, key technologies and merits of the OFDM and SC-FDE system are introduced and the relationship between time-frequency dualities is analyzed, which provide a reliable theoretical basis for the design of a reasonably practicable system model.Second, in the OFDM system, a novel pilot insertion method and different channel estimation methods are studied, and system performances are compared by computer simulation. The channel equalization method is researched on the basis of existing channel estimation method. In the aeronautical communication, The performance of OFDM system is poor, so this paper proposes a new program which is Turbo-encoding technology. BERs in the non-coding system and Turbo-encoding system are compared, and the system performances in the three decoding methods are analyzed. From the simulation, we can see that Turbo code method has better coding performance.Then, in this section, channel estimation and FDE algorithm in the SC-FDE are mainly studied, and computer simulations of pilot-based channel equalization and channel equalization based on the UW had been done. For the air channel, the performance of SC-FDE system is not good, this paper presents a new system which is SC-FDE system based on turbo encoding, through the computer simulation, the BER can be reduced effectively when the Turbo code is applied to the SC-FDE system. It's suitable for the high-speed and high-efficiency requirement of communication systems in the future.Finally, the theoretical analysis and simulation results of this paper are reviewed. Combining with the prospects for the future of communications, exploring OFDM system and SC-FDE system aspects are to be studied in the future.