Apparatus and method for compensating for a frequency offset in a wireless communication system

Abstract

Disclosed is an apparatus and method for compensating for frequency offset in a wireless communication system using an OFDM system which can compensate for phase change due to carrier frequency offset and sampling frequency offset of data carried on subcarriers. The apparatus includes an FFT window adjustment unit for receiving sampling data when a packet is received, setting a start point of a FFT window at a start point of long training symbols and adjusting a position of the FFT window according to an input window adjustment value, an FFT unit for receiving an output of the FFT window adjustment unit, transforming time-domain symbols into frequency-domain symbols and calculating FFT coefficients, a channel estimation unit for receiving the coefficients from the FFT unit, estimating a channel state and outputting a value for compensating for an estimated value, a channel compensation unit for compensating for the frequency-domain symbols using the output of the channel estimation unit and a phase error tracking and correction unit for receiving an output of the channel compensation unit, detecting a sampling frequency offset and a phase change of a carrier signal and outputting the window adjustment value to the FFT window adjustment unit.

Description

technical field [0001] The present invention relates to a device and method for compensating for frequency offset in a wireless communication system, and more particularly, to a method for compensating for wireless communication using an Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) system Apparatus and method for frequency offset in a system. Background technique [0002] Wireless communication systems transmit data using designated frequencies. Wireless communication systems have been classified into various types of wireless communication systems. A representative of the wireless communication system is a mobile communication system, which is briefly classified into a synchronous type mobile communication system and an asynchronous type mobile communication system. In addition, a system based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard has been proposed as a system in which fixed termina...

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Problems solved by technology

[0015] The first reason is the case where the receiver cannot be precisely synchronized with the carrier frequency generated in the transmitter

The second reason is that the sampling frequency used in the digital-to-analog converter (DAC, Digital-to-Analog Converter) of the transmitter is not precisely synchronized with the sampling frequency used in the DAC of the receiver

Therefore, if the phase change due to carrier frequency offset and the phase change with increasing subcarrier index cannot be accurately estimated and compensated, that is, if the frequency offset cannot be accurately compensated, the receiver will not be able to recover the transmitted signal

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