Method and apparatus for estimating and compensating frequency deviation in orthogonal multiplexing system

Abstract

The method includes steps: using mapping table lookup to simplify former a series of calculation of trigonometric function, and considering range of rotation phases in [0ú‘+ Pi]; when making phase compensation for OFDM symbol, adjusting sign digit if rotation phase in third, fourth quadrants; based on precision required by practical application, linear unbiased partitioning whole range of phase; based on equant size to determine magnitude of compensation factor list. The device includes frame synchronizer, frequency deviation estimator of carrier wave, unit for eliminating CP, unit of compensation factor list, and frequency deviation compensator of carrier wave. Using values of rotation phases calculated for each frame looks up list to obtain corresponding compensation factor. Using scheme of mapping table lookup, the invention solves disadvantages in maximum likelihood estimation method, where trigonometric function cannot be implemented in FPGA.

Description

technical field [0001] The invention relates to communication technology, in particular to a method and device for estimating and compensating frequency deviation by using training sequence in an OFDM communication system. Background technique [0002] Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM: Orthogonal Frequency Division Multiplexing) is a special multi-carrier modulation technology. The basic principle of transmitting data is to divide the data stream into several parallel bit streams and divide each Two such data streams are modulated on a single carrier. [0003] One of the main defects of OFDM is the sensitivity to carrier frequency offset. For a multi-carrier system, the offset of carrier frequency will cause interference between sub-channels. There are multiple orthogonal sub-carriers in the OFDM system, and its output signal It is the superposition of multiple sub-channel signals. For OFDM systems that require sub-carriers to mai...

AI Technical Summary

Problems solved by technology

[0030] Since FPGA (Field Programmable Gate Arrays,: Field Programmable Gate Array) is a hardware device based on large-scale logic units, it can be used to generate complex user logic, but trigonometric functions (such as sine, cosine, arctangent) cannot be used in FPGA Direct implementation, so that the above method of carrier frequency estimation and compensation, that is, the obtained real part a and imaginary step b are input into the phase calculator, and the output rotated phase value ∠z (need to use the arc tangent function) is then input into the frequency offset compensator Compensated complex results (need to use sine function, cosine function) cannot be directly designed into a specific device that can be used on FPGA

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