An Accurate Estimation Method for Large Frequency Offset in dft-s-ofdm System

Abstract

The invention provides a method for precisely estimating a large frequency offset of a DFT-s-OFDM (Direct Fourier Transformer Spread Orthogonal Frequency Division Multiplexing) system. The method comprises the following steps of synchronizing SC-OFMA (Single-Carrier Orthogonal Frequency Division Multiplexing) symbols; performing frequency offset estimation by utilization of a synchronized cyclic prefix CP and a data section tail part Tail so as to obtain a small frequency offset, and compensating the small frequency offset on a receiving signal; performing automatic RB (Resource Block) detection after removing the carrier leakage from the compensated receiving signal, and distributing sub carriers according to frequency domain RB so as to obtain a large frequency offset; generating a DMRS (Demodulation Reference Signal) local reference signal for a time slot under an unknown time slot number according to receiver DMRS symbols; obtaining a precise frequency offset according to an average phase difference of two DMRS symbols in one sub carrier, and obtaining a large frequency offset estimation range. According to the method for precisely estimating the large frequency offset of the DFT-s-OFDM system, the inter-symbol interference and the inter-sub carrier interference can be conquered, and the frequency offset estimation on signals is realized under the condition of unnecessarily knowing signal resource block allocation and sub frame sequence number in advance, so that the frequency offset range is enlarged, and the precision of the estimation result is improved.

Description

technical field [0001] The present invention relates to communication technology, in particular to a discrete Fourier transform spread spectrum orthogonal frequency division multiplexing (DirectFourier Transformer Spread Orthogonal Frequency Division Multiplexing, referred to as DFT-s-OFDM) system large frequency offset estimation method. Background technique [0002] Time Division Long Term Evolution (TD-LTE) downlink adopts Orthogonal Frequency Division Multiplexing (OFDM) technology, and uplink adopts DFT-s-OFDM technology. The OFDM system has anti-symbol Both Inter Symbol Interference (ISI for short) and Inter-Carrier Interference (ICI for short) have the advantage of low peak-to-average ratio. [0003] The LTE uplink DFT-s-OFDM system uses a cyclic prefix (CP for short), which can overcome the ISI and ICI caused by multipath delay, but the baseband signal will cause intersymbol interference due to multipath effects and frequency selection characteristics. Not orthogona...

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Problems solved by technology

[0003] The LTE uplink DFT-s-OFDM system uses a cyclic prefix (CP for short), which can overcome the ISI and ICI caused by multipath delay, but the baseband signal will cause intersymbol interference due to multipath effects and frequency selection characteristics. Not orthogonal to the subcarrier, the uplink carrier leakage is relatively large, which affects the demodulation performance of the receiver, specifically:

[0004] Because the DC component introduced by the transmitter will cause an impact signal at the zero frequency position of the signal, which will affect the automatic detection of resource block RB in the frequency domain; because the fluctuation of a single subcarrier is relatively large, and the interference of unallocated subcarriers is also Relatively large, which will affect the automatic detection of frequency domain allocation RB

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