A Method of Integer Frequency Offset Estimation Based on Ofdm Preamble

Abstract

The invention provides an integer frequency offset estimation method based on an OFDM preamble. The integer frequency offset estimation method comprises the following steps: firstly, obtaining an OFDM frequency domain preamble through FFT, circularly shifting the OFDM frequency domain preamble by d sampling positions and then performing conjugate multiplication on the circularly-shifted OFDM frequency domain preamble and a known frequency domain preamble at a receiving end to obtain signal; secondly, calculating difference correlation data, obtaining the absolute values of the difference correlation data and performing mean weighing accumulation on the absolute values to obtain a frequency offset estimation measure; and finally, obtaining the maximum value of the frequency offset estimation measure to obtain an integer frequency offset estimator. The integer frequency offset estimation method only requires one OFDM block preamble rather than using two preambles or inserting a pilot frequency in a data symbol; difference correlation is performed in the frequency domain of the OFDM signal to estimate the integer frequency offset and the estimation performance is not affected by the timing residual offset of the symbol; besides, an implementation structure of mean summation on Mo difference results is adopted to achieve a relatively low wrong detection probability under a multipath channel condition.

Description

technical field [0001] The invention relates to an integer frequency offset estimation method, in particular to an OFDM preamble-based integer frequency offset estimation method, belonging to the technical field of digital wireless communication transmission. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM) technology has the advantages of strong multipath resistance and high-speed information transmission support, and has been maturely applied in the field of ground mobile communications. In the fields of UAV measurement and control and broadband satellite mobile communication, OFDM can provide high-speed data transmission. For example, the high-definition messenger data link (HDML) of the US Global Microwave System (GMS) adopts the C-OFDM system, and the European satellite standard DVB-SH design A hybrid terrestrial and satellite communication system using OFDM or TDM technology. [0003] After the OFDM signal undergoes multipath channel fad...

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Problems solved by technology

Among them, the integer frequency offset estimation methods are mainly divided into two categories: time domain and frequency domain: time domain estimation methods such as the literature "Ren G L, Chang Y, Zhang H, et al. .IEEE Transactions on Broadcasting,2005,51(1):139-143."The estimation algorithm needs to complete accurate symbol timing synchronization in the OFDM time domain based on the preamble symbol, and its integer frequency offset estimation is greatly affected by the symbol timing synchronization performance ; The frequency domain estimation method such as the estimation algorithm in the literature "Morelli M, D'Andrea A N, Mengali U. Frequencyambiguity resolution in OFDM systems.IEEE Communications Letters, 2000 (4): 134-136." needs two continuous OFDM data The pilot data is inserted into the symbol, which cannot make full use of the leading symbol

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