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Wireless communication device

A wireless communication device and signal technology, applied in multiplex communication, electrical components, transmission systems, etc., can solve problems such as time-varying DC offset and IQ imbalance, etc.

Inactive Publication Date: 2007-11-21
SONY CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The receivers shown in Figures 18 to 20 do not account for time-varying DC offset and IQ imbalance

Method used

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no. 1 example

[0146] Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

[0147] The present invention contemplates a wireless communication device for receiving OFDM signals using a direct conversion architecture. A direct conversion architecture without the use of an IF filter easily implements a wideband receiver and increases receiver design flexibility.

[0148] A problem with OFDM communication systems is that small errors between the frequencies of the oscillators in the transmitter and receiver can cause a frequency offset, which is seen as a phase rotation phenomenon of the received signal in the digital part of the receiver. In a usual procedure, the frequency offset is observed and corrected for using a known training sequence added to the packet header of each packet.

[0149] However, direct conversion receivers have the problem of inducing a direct current component, or DC offset, at the output of the downconve...

no. 2 example

[0297] The direct conversion OFDM receiving apparatus according to the first embodiment uses a technique that can accurately estimate a frequency offset by simple signal processing even in the presence of IQ imbalance and time-varying DC offset. The apparatus according to the first embodiment aims to provide a proper frequency offset estimation, but not to perform IQ imbalance correction together with the frequency offset correction.

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Abstract

The invention provides a wireless communication device for receiving a package constituted by signal modulated by OFDM. A band-pass filter pick up OFDM signal of desired frequency band. The desired OFDM signal is amplified by low-pass amplifier based on the gain controlled by the received signal intensity. A frequency converter down-converses the FDM signal into baseband signal. An A / D converter converses the baseband signal into digital signal. A first high pass filter removes DC deviation from baseband signal corresponding to preset preamble of the package. A frequency shift etimator estimates frequency shift from the sampled signal which has removed DC deviation from baseband signal by the first high pass filter. A frequency shift corrector removes the estimated frequency shift from the baseband signal. A demodulator demodulates the subcarrier signal in the frequency domain from baseband signal which is compensated with frequency shift.

Description

[0001] Cross References to Related Applications [0002] The present invention consists of Japanese patent applications JP 2006-137047 filed with the Japan Patent Office on May 16, 2006, JP 2007-037719 filed with the Japan Patent Office on February 19, 2007, and JP 2007-037719 filed with the Japan Patent Office on April 17, 2007 Subject matter of JP2007-108046 filed, the entire contents of which are hereby incorporated by reference. technical field [0003] The present invention relates to wireless communication devices for receiving radio frequency (RF) signals modulated by Orthogonal Frequency Division Multiplexing (OFDM). In particular, the present invention relates to wireless communication devices for receiving signals using a direct conversion architecture that does not utilize an intermediate frequency (IF) stage. [0004] More particularly, the present invention relates to a wireless communication device for removing a frequency offset and demodulating OFDM symbols us...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04J11/00H04B1/12
Inventor 真田幸俊横岛英城阿部雅美近藤裕也稻森真美子西城和幸
Owner SONY CORP
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