Frequency synchronization method based on joint estimation of carrier frequency offset

Abstract

The invention relates to a frequency synchronization method based on joint estimation carrier of frequency offset, belonging to the technical field of wireless mobile communication. The frequency synchronization method comprises the steps of: carrying out coarse frequency synchronization by using a short training field so as to correct integer frequency offset and carrying out frequency offset compensation on the basis of a coarse frequency synchronization result; by using a signal subjected to frequency offset compensation and a long training field, in combination with a segmentation related algorithm, carrying out frequency estimation to obtain a carrier frequency offset 1; obtaining a carrier frequency offset 2 on the basis of an MMSE (Minimum Mean Square Error) criterion; further obtaining a carrier frequency offset 3 on the basis of a mean square error criterion, and giving frequency synchronization results in different wireless channel environments; and finally, on the basis of the frequency synchronization results, carrying out frequency offset correction on a received signal. According to the frequency synchronization method, the synchronization mean square error of a wireless system is greatly lowered and the synchronization precision is effectively improved.

Description

technical field [0001] The invention relates to a frequency synchronization method for jointly estimating carrier frequency offset, which belongs to the technical field of wireless mobile communication. Background technique [0002] With the rapid development of military and civilian wireless communication systems, the physical layer architecture of OFDM technology combined with multi-antenna technology can achieve high spectral efficiency and high-speed broadband wireless transmission. The data symbol transmission rate can be as high as 100Mbps or more, and with the increase in the number of antennas and the improvement of key technologies in the wireless mobile field, the signal coverage effect is getting better and better. By using array antennas in the OFDM transmission system to achieve space diversity, the tolerance of the wireless system to noise, interference, and multipath is greatly increased, and the transmission rate of the wireless communication system is greatl...

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Problems solved by technology

[0003] In 2003, the Journal of the University of Electronic Science and Technology of China "A OFDM Frequency Synchronization Using PN Sequence" described the frequency synchronization based on the PN preamble sequence. This algorithm is simple to implement, but the accuracy is not high enough

[0004] In September 2008, "OFDM Synchronization Algorithm Based on CAZAC Sequence" in Applied Science and Technology Magazine respectively explained the frequency synchronization based on the preamble sequence with constant envelope autocorrelation characteristics, and the preamble sequence is a repeated training sequence, which has the advantage of not being easily affected by the frequency The impact of bias injection noise, but not combined with multi-antenna technology for data transmission, not suitable for multi-antenna MIMO systems

[0005] In 2008, the patent application number CN101309248A, titled "Frequency Synchronization Method and Device Used in OFDM Communication System", provided a frequency synchronization method and frequency offset synchronization device for OFDM communication system for OFDM system, although it can be used in the digital domain Up-compensate frequency offset and eliminate the impact of virtual carrier and FFT points that are not integer multiples of subcarrier spacing on time-domain periodicity, but does not combine multi-antenna technology, and the accuracy of carrier frequency offset estimation is not high

[0006] In 2009, Zhejiang University's master's degree thesis "Research on Synchronization Technology Based on 802.11n Wireless Local Area Network" proposed an improved frequency synchronization algorithm for the structural characteristics of the preamble training symbols of wireless LAN, although compared with the traditional frequency synchronization method, it can reduce the The mean square error of frequency offset estimation, but has the disadvantage of low synchronization accuracy

[0007] In 2012, the application number CN102546514A, the patent titled "Method and Equipment for Frequency Synchronization of OFDM System", proposed the use of digital phase-locked loop mechanism for OFDM system to realize the joint estimation of carrier frequency offset and sampling frequency offset, reducing the complexity of implementation And it improves the estimation accuracy, but it is also not suitable for multi-antenna MIMO systems

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