Method of symbol timing synchronization and carrier synchronization applied to OFDM system

Abstract

The invention discloses a method of symbol timing synchronization and carrier synchronization applied to an OFDM system. The method comprises the following steps that a transmitter module of the OFDM system sends a first training sequence and a second training sequence before an effective OFDM symbol; accurate symbol timing synchronization is carried out according to the first training sequence in a receiving process; thick carrier frequency offset estimation is carried out according to the received first training sequence; thin carrier frequency offset estimation is carried out according to the received first training sequence and the received second training sequence; correction is carried out on the thin carrier frequency offset estimation according to thin carrier frequency offset estimation values; total carrier frequency offset is calculated according to the results of the first step and the third step; and carrier frequency offset compensation is carried out according to the last step. The method of the symbol timing synchronization and the carrier synchronization applied to the OFDM system is not only low in complexity, but also good in performance, the timing error of the timing synchronization and the error of mean square of the carrier frequency offset estimation are both small, the method is insensitive to signal noise and the carrier frequency offset, and the maximum range capable of being estimated is four times of subcarrier spacing.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a symbol timing synchronization and carrier synchronization method applied to an OFDM system. Background technique [0002] Orthogonal Frequency Division Multiplexing, hereinafter referred to as OFDM, is a modulation scheme for high-speed data transmission. The OFDM modulation scheme decomposes a set of high-rate serial data streams into low-rate parallel data streams, and then uses low-rate data to modulate corresponding subcarriers, forming a transmission system in which multiple low-rate data are sent in parallel. Its characteristic is that each sub-carrier is orthogonal to each other, and the modulated spectrum can overlap with each other, which not only reduces the mutual interference between sub-carriers, but also greatly improves the frequency utilization. [0003] Because OFDM technology has the advantages of anti-frequency selective fading and narrow-b...

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Problems solved by technology

After reviewing journal papers, it was found that Timothy M.Schmidl and Donald C.Cox et al proposed the SC algorithm (Robust Frequency and Timing Synchronization for OFDM, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL.45, NO.12, DECEMBER1997), Minn et al proposed Minn algorithm (On timing offset estimation for OFDM systems, IEEE Commun.Lett., vol.4, pp.242–244, July2000), these two algorithms have low complexity, but poor performance

Park et al. (“A Novel Timing Estimation Method for OFDM Systems” IEEE COMMUNICATIONS LETTERS, VOL.7, NO.5, MAY2003) proposed a timing synchronization scheme with excellent performance, but this method requires A large number of multiplication and addition operations, the hardware overhead is too large, and it is not easy to implement

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