OFDM signal receiving apparatus and OFDM signal receiving method

• US 20050073949A1
• Filed: 10/01/2004
• Published: 04/07/2005
• Est. Priority Date: 10/01/2003
• Status: Active Grant

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Hayashi, Kenichiro
• Granted Patent: US 7,535,820 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03522 Frequency domain
• CPC Class Codes: H04L 25/0216 with estimation of channel length
• CPC Class Codes: H04L 25/0218 with detection of nulls
• CPC Class Codes: H04L 25/0234 by non-linear interpolation
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

An OFDM signal receiver reduces frequency response estimation error, and reduces the circuit scale needed for a hardware implementation and the number of operations performed in a software implementation. A first Fourier transform circuit converts an OFDM signal to the frequency domain by a Fourier transform. A first divider divides the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal. A zero insertion means then inserts zero signals in the first divider output. A window function multiplying means multiplies the zero insertion means output by a window function, and an inverse Fourier transform means applies an inverse Fourier transform to the multiplier output. A coring means then cores the inverse Fourier transform output, and truncation means truncates the coring means output at a specified data length. A second Fourier transform circuit applies another Fourier transform to the truncated result. A window function dividing means then divides the Fourier transform result by the window function, and a second dividing means divides the output of the first Fourier transform means by the output of the window function dividing means.

Claims

1. An OFDM signal receiving apparatus for receiving OFDM (orthogonal frequency division multiplexing) signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a zero insertion means for inserting zero signals to the first frequency response, and generating a second frequency response;

a window function multiplying means for multiplying the second frequency response by a window function, and generating a third frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the third frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a truncation means for truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a second Fourier transform means for generating a fourth frequency response by a Fourier transform of the third impulse response;

a window function dividing means for dividing the fourth frequency response by the window function, and generating a fifth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

2. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a zero insertion means for inserting zero signals to the first frequency response, and generating a second frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the second frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a truncation means for truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a second Fourier transform means for generating a third frequency response by a Fourier transform of the third impulse response;

a time axis interpolation means for interpolating the first frequency response along the time axis, and generating a fourth frequency response;

a frequency axis interpolation means for interpolating the fourth frequency response along the frequency axis, and generating a fifth frequency response;

a selection means for selecting the third frequency response for carriers within a specific range of the signal band center, selecting the fifth frequency response for the remaining carriers near the signal band edges, and generating a sixth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

3. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a zero insertion means for inserting zero signals to the first frequency response, and generating a second frequency response;

a window function multiplying means for multiplying the second frequency response by a window function, and generating a third frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the third frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a truncation means for truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a second Fourier transform means for generating a fourth frequency response by a Fourier transform of the third impulse response;

a window function dividing means for dividing the fourth frequency response by the window function, and generating a fifth frequency response;

a time axis interpolation means for interpolating the first frequency response along the time axis, and generating a sixth frequency response;

a frequency axis interpolation means for interpolating the sixth frequency response along the frequency axis, and generating a seventh frequency response;

a selection means for selecting the fifth frequency response for carriers within a specific range of the signal band center, selecting the seventh frequency response for the remaining carriers near the signal band edges, and generating an eighth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the eighth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

4. (canceled)

5. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the first frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a second frequency response by a Fourier transform of the second impulse response;

a time axis interpolation means for interpolating the second frequency response along the time axis, and generating a third frequency response;

a frequency axis interpolation means for interpolating the third frequency response along the frequency axis, and generating a fourth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the fourth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

6. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a window function multiplying means for multiplying the first frequency response by a window function, and generating a second frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the second frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a third frequency response by a Fourier transform of the second impulse response;

a window function dividing means for dividing the third frequency response by the window function, and generating a fourth frequency response;

a time axis interpolation means for interpolating the fourth frequency response along the time axis, and generating a fifth frequency response;

a frequency axis interpolation means for interpolating the fifth frequency response along the frequency axis, and generating a sixth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

7. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the first frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a second frequency response by a Fourier transform of the second impulse response;

a selection means for selecting the second frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a third frequency response;

a time axis interpolation means for interpolating the third frequency response along the time axis, and generating a fourth frequency response;

a frequency axis interpolation means for interpolating the fourth frequency response along the frequency axis, and generating a fifth frequency response;

a second dividing means for dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

8. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a window function multiplying means for multiplying the first frequency response by a window function, and generating a second frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the second frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a third frequency response by a Fourier transform of the second impulse response;

a window function dividing means for dividing the third frequency response by the window function, and generating a fourth frequency response;

a selection means for selecting the fourth frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a fifth frequency response;

a time axis interpolation means for interpolating the fifth frequency response along the time axis, and generating a sixth frequency response;

a frequency axis interpolation means for interpolating the sixth frequency response along the frequency axis, and generating a seventh frequency response;

a second dividing means for dividing the frequency domain OFDM signal by the seventh frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

9-10. -10. (canceled)

11. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a window function multiplying means for multiplying the first frequency response by a window function, and generating a second frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the second frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a third frequency response by a Fourier transform of the second impulse response;

a window function dividing means for dividing the third frequency response by the window function, and generating a fourth frequency response;

a holding means for holding the fourth frequency response for a specific time, and generating a fifth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

12. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the first frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a second frequency response by a Fourier transform of the second impulse response;

a selection means for selecting the second frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a third frequency response;

a holding means for holding the third frequency response for a specific time, and generating a fourth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the fourth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

13. An OFDM signal receiving apparatus for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a first Fourier transform means for generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a first dividing means for dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a window function multiplying means for multiplying the first frequency response by a window function, and generating a second frequency response;

an inverse Fourier transform means for generating a first impulse response by an inverse Fourier transform of the second frequency response;

a coring means for replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a second Fourier transform means for generating a third frequency response by a Fourier transform of the second impulse response;

a window function dividing means for dividing the third frequency response by the window function, and generating a fourth frequency response;

a selection means for selecting the fourth frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a fifth frequency response;

a holding means for holding the fifth frequency response for a specific time, and generating a sixth frequency response; and

a second dividing means for dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

14-20. -20. (canceled)

21. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of inserting zero signals to the first frequency response, and generating a second frequency response;

a step of multiplying the second frequency response by a window function, and generating a third frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the third frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a step of generating a fourth frequency response by a Fourier transform of the third impulse response;

a step of dividing the fourth frequency response by the window function, and generating a fifth frequency response; and

a step of dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

22. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of inserting zero signals to the first frequency response, and generating a second frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the second frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a step of generating a third frequency response by a Fourier transform of the third impulse response;

a step of interpolating the first frequency response along the time axis, and generating a fourth frequency response;

a step of interpolating the fourth frequency response along the frequency axis, and generating a fifth frequency response;

a step of selecting the third frequency response for carriers within a specific range of the signal band center, selecting the fifth frequency response for the remaining carriers near the signal band edges, and generating a sixth frequency response; and

a step of dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

23. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of inserting zero signals to the first frequency response, and generating a second frequency response;

a step of multiplying the second frequency response by a window function, and generating a third frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the third frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of truncating the second impulse response at a specified data length, replacing other data with zero signals, and generating a third impulse response;

a step of generating a fourth frequency response by a Fourier transform of the third impulse response;

a step of dividing the fourth frequency response by the window function, and generating a fifth frequency response;

a step of interpolating the first frequency response along the time axis, and generating a sixth frequency response;

a step of interpolating the sixth frequency response along the frequency axis, and generating a seventh frequency response;

a step of selecting the fifth frequency response for carriers within a specific range of the signal band center, selecting the seventh frequency response for the remaining carriers near the signal band edges, and generating an eighth frequency response; and

a step of dividing the frequency domain OFDM signal by the eighth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

24. (canceled)

25. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the first frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a second frequency response by a Fourier transform of the second impulse response;

a step of interpolating the second frequency response along the time axis, and generating a third frequency response;

a step of interpolating the third frequency response along the frequency axis, and generating a fourth frequency response; and

a step of dividing the frequency domain OFDM signal by the fourth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

26. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of multiplying the first frequency response by a window function, and generating a second frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the second frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a third frequency response by a Fourier transform of the second impulse response;

a step of dividing the third frequency response by the window function, and generating a fourth frequency response;

a step of interpolating the fourth frequency response along the time axis, and generating a fifth frequency response;

a step of interpolating the fifth frequency response along the frequency axis, and generating a sixth frequency response; and

a step of dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

27. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the first frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a second frequency response by a Fourier transform of the second impulse response;

a step of selecting the second frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a third frequency response;

a step of interpolating the third frequency response along the time axis, and generating a fourth frequency response;

a step of interpolating the fourth frequency response along the frequency axis, and generating a fifth frequency response;

a step of dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

28. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of multiplying the first frequency response by a window function, and generating a second frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the second frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a third frequency response by a Fourier transform of the second impulse response;

a step of dividing the third frequency response by the window function, and generating a fourth frequency response;

a step of selecting the fourth frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a fifth frequency response;

a step of interpolating the fifth frequency response along the time axis, and generating a sixth frequency response;

a step of interpolating the sixth frequency response along the frequency axis, and generating a seventh frequency response;

a step of dividing the frequency domain OFDM signal by the seventh frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

29-30. -30. (canceled)

31. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of multiplying the first frequency response by a window function, and generating a second frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the second frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a third frequency response by a Fourier transform of the second impulse response;

a step of dividing the third frequency response by the window function, and generating a fourth frequency response;

a step of holding the fourth frequency response for a specific time, and generating a fifth frequency response; and

a step of dividing the frequency domain OFDM signal by the fifth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

32. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the first frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a second frequency response by a Fourier transform of the second impulse response;

a step of selecting the second frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a third frequency response;

a step of holding the third frequency response for a specific time, and generating a fourth frequency response; and

a step of dividing the frequency domain OFDM signal by the fourth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

33. An OFDM signal receiving method for receiving OFDM signals containing a pilot signal of known amplitude and phase, comprising:

a step of generating an OFDM signal in the frequency domain by a Fourier transform of the OFDM signal;

a step of dividing the pilot signal contained in the frequency domain OFDM signal by a specified pilot signal, and generating a first frequency response;

a step of multiplying the first frequency response by a window function, and generating a second frequency response;

a step of generating a first impulse response by an inverse Fourier transform of the second frequency response;

a step of replacing data in the first impulse response less than or equal to a specified threshold value with zero signals, and generating a second impulse response;

a step of generating a third frequency response by a Fourier transform of the second impulse response;

a step of dividing the third frequency response by the window function, and generating a fourth frequency response;

a step of selecting the fourth frequency response for carriers within a specific range of the signal band center, selecting the first frequency response for the remaining carriers near the signal band edges, and generating a fifth frequency response;

a step of holding the fifth frequency response for a specific time, and generating a sixth frequency response; and

a step of dividing the frequency domain OFDM signal by the sixth frequency response to compensate for amplitude and phase distortion introduced to the signal on the channel.

34-100. -100. (canceled)