Correlation detection apparatus and fourier transform apparatus

• US 20040042388A1
• Filed: 06/18/2003
• Published: 03/04/2004
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Hitachi Kokusai Electric Incorporated (Hitachi, Ltd.)
• Original Assignee: Hitachi Kokusai Electric Incorporated (Hitachi, Ltd.)
• Inventors: Yotsumoto, Koji, Abe, Shunji
• Granted Patent: US 7,450,492 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/7113 Determination of path profile
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects

Abstract

A correlation detection apparatus which realizes software CDMA inverse-spread processing. A reception circuit receives an RACH preamble from a mobile station, and an A/D converts the preamble into digital received data. An FFT unit FFT-processes the received data to obtain an FFT result. An RACH code storage unit holds an RACH preamble code, and another FFT unit FFT-processes the RACH preamble code to obtain another FFT result. A multiplication unit multiples the FFT result by the other FFT result. An IFFT unit IFFT-processes a result of multiplication input from the multiplication unit to obtain a delay profile. A data decoding unit decodes the received data by using the delay profile, and obtains decoded data.

Claims

1. A correlation detection apparatus for detecting a first signal in a time domain including predetermined code, and a correlation between the first signal and the predetermined code, comprising:

transform means for transforming the first signal in the time domain into a frequency domain;

correlation-signal generation means for generating a correlation signal indicating a correlation between the predetermined code transformed to the frequency domain and the first signal transformed to the frequency domain; and

correlation detection means for inverse-transforming the generated correlation signal into a signal in the time domain and detecting the correlation between the first signal and the predetermined code.

2. The correlation detection apparatus according to claim 1, wherein the transform means transform the first signal into the frequency domain by performing Fourier transform processing on the first signal in the time domain,

wherein the correlation-signal generation means generate the correlation signal by multiplying the predetermined code transformed to the frequency domain by the first signal transformed to the frequency domain, and

wherein the correlation detection means detect the correlation between the first signal and the predetermined code by performing inverse Fourier transform on the generated correlation signal.

3. A Fourier transform apparatus for performing Fourier transform by performing an N-stage butterfly operation on M^N time-series data by using M^N (M is a radix in Fourier transform;

N=1, 2, . . . ) continuous storage regions, comprising;

data storage means for storing (I;

I=0, 1, . . . , M^N−

1) th data into (M<sup>N−

1</sup>([I/M⁰]modM)+M<sup>N−

2</sup>([I/M¹]modM)+ . . . + M°

([I/M<sup>N−

1</sup>]modM);

[X] is an integer not exceeding X;

YmodZ is residue system of integer Y for integer Z)th storage region;

first butterfly-operation processing means for repeating processing of storing respective (MJ+H)th M pieces of data, obtained by performing a (J)th butterfly operation on data stored in (MJ+H;

J=0, 1, . . . , M<sup>N−

1</sup>, H=0 to M−

1)th M storage regions, into (M<sup>N−

1</sup>H+M<sup>N−

2</sup>([J/M¹]modM)+ . . . + M°

([J/M<sup>N−

1</sup>]modM))th M storage regions, (N−

1) times; and

second butterfly-operation processing means for performing processing of storing respective (MJ+H)th M pieces of data, obtained by performing a butterfly operation on the data obtained as a result of the (N−

1)th butterfly operation and stored in the (MJ+H)th M storage regions, into (M<sup>N−

1</sup>([J/M¹]modM)+ . . . + sM°

([J/M<sup>N−

1</sup>]modM)+H)th M storage regions.

4. An inverse Fourier transform apparatus for performing inverse Fourier transform by performing an N-stage butterfly operation on M^N pieces of time-series data by using M^N (M is a radix in inverse Fourier transform;

N=1, 2, . . . ) continuous storage regions, comprising;

third butterfly-operation processing means for repeating processing of storing respective (MJ+H)th M pieces of data, obtained by performing a (J)th butterfly operation on data stored in (MJ+H;

J=0, 1, . . . , M<sup>N−

1</sup>−

1, H=0, 1, . . . , M−

1)th M storage regions, into (M<sup>N−

1</sup>H+M<sup>N−

2</sup>([J/M¹]modM)+ . . . + Mo([J/M<sup>N−

1</sup>]modM))th M storage regions, (N) times.