ofdm receiving synchronization device

Abstract

The embodiment of the present invention discloses an OFDM receiving synchronization device, including a frame synchronization module, a carrier frequency synchronization module, and a symbol synchronization module, and the frame synchronization module includes a first delay autocorrelation unit, a 64-point averaging unit, and a complex modulus unit And a frame detection unit; the frequency synchronization module includes a second delay autocorrelation unit, a 16-point averaging unit, a frequency offset estimation unit, and a frequency offset correction unit, and the symbol synchronization module includes a cross-correlation unit. By adopting the invention, while improving the receiving accuracy, the complexity of the algorithm and the difficulty of hardware realization are reduced, and the low power consumption and low delay of the OFDM receiving end are realized.

Description

technical field [0001] The present invention relates to the technical application field of OFDM (Orthogonal Frequency Division Multiplexing), in particular to an OFDM receiving synchronization device Background technique [0002] Since the subcarriers of the OFDM system are mutually orthogonal, although this improves the spectrum utilization rate, it also brings new problems. Compared with single-carrier communication, it is easily affected by frequency deviation. The orthogonality between them puts forward very strict requirements, whether it is the frequency deviation in the wireless channel, the frequency deviation between the crystal oscillator of the transmitter and the receiver, and the sampling frequency deviation of A / D and D / A will cause sub- The destruction of carrier orthogonality leads to inter-channel interference (ICI), and the data at the receiving end cannot be recovered reliably, thereby reducing the performance of the entire system. Therefore, precise synch...

AI Technical Summary

Problems solved by technology

[0003] Data-assisted synchronization algorithms need to insert training sequences, which reduces the efficiency of data transmission. However, this type of method has the advantages of high estimation accuracy and low computational complexity. Two OFDM symbols are used as training sequences for time and frequency synchronization. The first half and the second half of a symbol are the same, which can be used for time synchronization and frequency fine synchronization, and the relationship between the two symbols before and after is used for coarse frequency synchronization

The disadvantage of this synchronization method is that the objective function of time synchronization is relatively flat, and the synchronization accuracy is not enough

Although the algorithm complexity is low, the effect is not very ideal

[0004] The blind synchronization method does not require additional data as a training sequence and has the advantage of high bandwidth efficiency, but the blind synchronization method generally has a high computational complexity

The blind synchronization method includes the time and frequency synchronization method using the cyclic prefix proposed by Van de Beek. Since the cyclic prefix is ​​used to resist multipath delay extension, using it for synchronization does not need to increase new overhead, which improves the system performance. Efficiency, but the disadvantage is that the frequency offset estimation range does not exceed half a subcarrier interval, and the time synchronization is not very accurate in multipath fading channels

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