US 7,609,615 B2Granted

Method and apparatus for performing channel compensation and symbol demodulation for coherent demodulation in an OFDM system

AssigneeSamsung Electronics Co., Ltd.

InventorsEun-Jeong Yim, Ji-Won Ha, Hee-Jin Roh, Sung-Jin Park

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Abstract

A method and apparatus for performing channel compensation and symbol demodulation using an estimated channel impulse response during coherent demodulation of a received Orthogonal Frequency Division Multiplexing (OFDM) signal are provided. In the apparatus, an FFT processor IFFT-processes a received signal. A channel compensator generates a channel-compensated signal by multiplying the FFT received signal by an estimated channel impulse response and calculates the power of the estimated channel impulse response. A symbol demodulator sets the power of the estimated channel impulse response as a reference point defining a minimum distance between signal points in a signal constellation, and decides soft metric values for channel decoding using the reference point and I-channel and Q-channel signal components of the channel-compensated signal. A decoder recovers information bits by decoding the soft metric values.

Claims4

Dependent claims

A method of performing channel compensation and symbol demodulation on a received signal in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:

generating a channel-compensated signal by multiplying a fast Fourier transform (FFT) received signal by an estimated channel impulse response;
calculating the power of the estimated channel impulse response;
and
setting the power of the estimated channel impulse response as a reference point value defining a minimum distance between signal points in a signal constellation used for modulation of the FFT received signal, and deciding soft metric values for channel decoding of the channel-compensated signal using the reference point value, I-channel and Q-channel signal components of the channel-compensated signal, and a multiple of the reference point value corresponding to the distance of a signal point closest to the origin to each axis in the signal constellation,
wherein 16-ary Quadrature Amplitude Modulation (16QAM) is used and the channel-compensated signal modulates the deciding of soft metric values which comprises deciding soft metric values for the channel-compensated signal by
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232 more elements

A receiving apparatus in an Orthogonal Frequency Division Multiplexing (OFDM) system, comprising:

a Fast Fourier Transform (FFT) processor for Inverse Fast Fourier transform (IFFT)-processing a received signal;
a channel compensator for generating a channel-compensated signal by multiplying the FFT received signal by an estimated channel impulse response and calculating the power of the estimated channel impulse response;
a symbol demodulator for setting the power of the estimated channel impulse response as a reference point value defining a minimum distance between signal points in a signal constellation used for modulation of the FFT received signal, and deciding soft metric values for channel decoding of the channel-compensated signal using the reference point value, I-channel and Q-channel signal components of the channel-compensated signal, and a multiple of the reference point value corresponding to the distance of a signal point closest to the origin to each axis in the signal constellation;
and
a decoder for recovering information bits by decoding the soft metric values,
wherein the symbol demodulator uses 16-ary Quadrature Amplitude Modulation (16QAM) and decides soft metric values which comprises the deciding of soft metric values for the channel-compensated signal by
Z
k
=

Y
k

-
2
⁢
a
⁢
⁢
Λ
⁡
(
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,
2
)
=
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+
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,
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where
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and
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(
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,
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)
=
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k
′
where Yk and Xk denote the Q-channel signal component and the I-channel signal component of the channel-compensated signal, respectively, (Sk,3), (Sk,2), (Sk,1) and (Sk,0) denote the soft metric values, a comprises the reference point value, S denotes the multiple of the reference point value corresponding to the distance of a signal point closest to the origin to each axis in the signal constellation, equal to the minimum distance between signal points, and k denotes a symbol index.

233 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/455,784Filed 20 Jun 2006
Priority: KR 10-2005-005294320 Jun 2005
Published: US 2006/0285603 A121 Dec 2006
Granted: 27 Oct 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04L 25/0212
Channel estimation: of impulse response
H04L 25/03292
Arrangements for operating in conjunction with other apparatus: with channel estimation circuitry
H04L 25/03318
Arrangements specific to the provision of output signals: provision of soft decisions
H04L 27/265
Demodulators: fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators

Family

US 2006/0285603 A1Pre-grant publication · published 21 Dec 2006
US 7,609,615 B2This patent

From the US filing history. Foreign family members aren’t listed.

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