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Frequency Synchronization Algorithm for Improving Performance of OFDMA System in 3GPP LTE Downlink  

Lee, Dae-Hong (삼성탈레스)
Im, Se-Bin (성균관대학교 정보통신공학부)
Roh, Hee-Jin (삼성전자 정보통신총괄 통신연구소)
Choi, Hyung-Jin (성균관대학교 정보통신공학부)
Publication Information
The Journal of Korean Institute of Communications and Information Sciences / v.34, no.1C, 2009 , pp. 120-130 More about this Journal
Abstract
In this paper, we propose a receiver structure for frequency synchronization in OFDMA (Orthogonal Frequency Division Multiple Access) system which is considered as 3GPP LTE(Long Term Evolution) downlink. In general, OFDMA frequency synchronization consists of two parts: coarse synchronization and fine synchronization. We consider P-SCH (Primary-Synchronization Channel) and CP (Cyclic Prefix) of OFDMA symbol for coarse synchronization and fine synchronization, respectively. The P-SCH signal has two remarkable disadvantages that it does not have sufficiently many sub-carriers and its differential correlation characteristic is not good due to ZC (Zadoff Chu) sequence-specific property. Hence, conventional frequency synchronization algorithms cannot obtain satisfactory performance gain. In this paper, we propose a modified differential correlation algorithm to improve performance of the coarse frequency synchronization. Also, we introduce an effective PLL (Phase Locked Loop) structure to guarantee stable performance of the fine frequency synchronization. Simulation results verify that the proposed algorithm has superior performance to the conventional algorithms and the 2nd-order PLL is effective to track the fine frequency offset even in high mobility.
Keywords
3GPP LTE; OFDMA; frequency synchronization;
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