Apparatus and method for FT pre-coding of data and control signals to reduce PAPR in a multi-carrier wireless network

• US 20060262870A1
• Filed: 03/14/2006
• Published: 11/23/2006
• Est. Priority Date: 05/19/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Khan, Farooq
• Granted Patent: US 8,019,006 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2615 Reduction thereof using coding

Abstract

A subscriber station is provided for use in a wireless network communicating according to a multi-carrier protocol, such as OFDM or OFDMA. The subscriber station comprises: a size M1 Fourier Transform (FT) block that receives input symbols and generates M1 FT pre-coded outputs; a size M2 Fourier Transform (FT) block that receives input symbols and generates M2 FT pre-coded outputs; and a size N inverse Fourier Transform (IFT) block that receives N inputs, including the M1 FT pre-coded outputs and the M2 FT pre-coded outputs, and generates N outputs to be transmitted to a base station. The FT blocks are Fast Fourier Transform blocks or Discrete Fourier Transform blocks. The IFT block is an inverse Fast Fourier Transform block or an inverse Discrete Fourier Transform block.

Claims

1. For use in a wireless network, a subscriber station capable of communicating with the wireless network according to a multi-carrier protocol, the subscriber station comprising:

a size M1 Fourier Transform (FT) block capable of receiving input symbols and generating therefrom M1 FT pre-coded outputs;

a size M2 Fourier Transform (FT) block capable of receiving input symbols and generating therefrom M2 FT pre-coded outputs; and

a size N inverse Fourier Transform (IFT) block capable of receiving N inputs, the N inputs including the M1 FT pre-coded outputs from the size M1 FT block and the M2 FT pre-coded outputs from the size M2 FT block, and generating therefrom N outputs to be transmitted to a base station of the wireless network.

2. The subscriber station as set forth in claim 1, wherein the size M1 FT block and the size M2 FT block are one of:

1) Fast Fourier Transform (FFT) blocks and

     2) Discrete Fourier Transform (DFT) blocks, and the size N IFT block is one of;

     1) an inverse Fast Fourier Transform (IFFT) block and

     2) an inverse Discrete Fourier Transform (IDFT) block.

3. The subscriber station as set forth in claim 2, wherein the value of N is greater than or equal to the sum of M1 and M2.

4. The subscriber station as set forth in claim 2, wherein the size N IFT block receives on at least some of N−

(M1+M2) inputs signaling and control symbols that have not been FT pre-coded by either the size M1 FT block or the size M2 FT block.

5. The subscriber station as set forth in claim 2, wherein the size N IFT block receives on at least some of N−

(M1+M2) inputs user data symbols that have not been FT pre-coded by either the size M1 FT block or the size M2 FT block.

6. The subscriber station as set forth in claim 2, wherein the input symbols to the size M1 FT block comprise at least one of 1) user data symbols and 2) signaling and control symbols to be transmitted to the base station.

7. The subscriber station as set forth in claim 6, wherein the signaling and control symbols comprise a pilot signal.

8. The subscriber station as set forth in claim 2, wherein the input symbols to the size M2 FT block comprise at least one of 1) user data symbols and 2) signaling and control symbols to be transmitted to the base station.

9. The subscriber station as set forth in claim 8, wherein the signaling and control symbols comprise a pilot signal.

10. The subscriber station as set forth in claim 2, wherein the multi-carrier protocol comprises one of orthogonal frequency division multiplexing and orthogonal frequency division multiple access.

11. For use in a subscriber station capable of communicating with a wireless network according to a multi-carrier protocol, a method for reducing the peak-to-average power ration (PAPR) of a radio frequency signal transmitted by the subscriber station to a base station of the wireless network, the method comprising the steps of:

receiving input symbols to be transmitted to the base station;

performing a size M1 Fourier Transform (FT) operation on a first subset of the received input symbols to thereby generate M1 FT pre-coded outputs;

performing a size M2 Fourier Transform (FT) operation on a second subset of the received input symbols to thereby generate M2 FT pre-coded outputs; and

performing a size N inverse Fourier Transform (IFT) operation on N inputs, the N inputs including the M1 FT pre-coded outputs and the M2 FT pre-coded outputs, to thereby generate N outputs to be transmitted to the base station.

12. The method as set forth in claim 11, wherein the size M1 FT operation and the size M2 FT operation are one of:

1) Fast Fourier Transform (FFT) operations and

     2) Discrete Fourier Transform (DFT) operations, and the size N IFT operation is one of;

     1) an inverse Fast Fourier Transform (IFFT) operation and

     2) an inverse Discrete Fourier Transform (IDFT) operation.

13. The method as set forth in claim 12, wherein the value of N is greater than or equal to the sum of M1 and M2.

14. The method as set forth in claim 12, wherein the size N IFT operation receives on at least some of N−

(M1+M2) inputs signaling and control symbols that have not been FT pre-coded by either the size M1 FT operation or the size M2 FT operation.

15. The method as set forth in claim 12, wherein the size N IFT operation receives on at least some of N−

(M1+M2) inputs user data symbols that have not been FT pre-coded by either the size M1 FT operation or the size M2 FT operation.

16. The method as set forth in claim 12, wherein the input symbols to the size M1 FT operation comprise at least one of 1) user data symbols and 2) signaling and control symbols to be transmitted to the base station.

17. The method as set forth in claim 16, wherein the signaling and control symbols comprise a pilot signal.

18. The method as set forth in claim 12, wherein the input symbols to the size M2 FT operation comprise at least one of 1) user data symbols and 2) signaling and control symbols to be transmitted to the base station.

19. The method as set forth in claim 18, wherein the signaling and control symbols comprise a pilot signal.

20. The method as set forth in claim 12, wherein the multi-carrier protocol comprises one of orthogonal frequency division multiplexing and orthogonal frequency division multiple access.

21. A base station for use in a wireless network capable of communicating with subscriber stations according to a multi-carrier protocol, the base station comprising:

down-conversion circuitry capable of receiving incoming radio frequency signals from the subscriber stations and generating therefrom a baseband signal;

a size N Fourier Transform (FT) block capable of receiving the baseband signal on N inputs and performing an FT operation to generate N outputs;

a size M1 Inverse Fourier Transform (IFT) block capable of receiving M1 outputs of the size N FT block and performing a size M1 IFT operation on the M1 outputs to generate a first plurality of symbols transmitted by a first one of the subscriber stations; and

a size M2 Inverse Fourier Transform (IFT) block capable of receiving M2 outputs of the size N FT block and performing a size M2 IFT operation on the M2 outputs to generate a second plurality of symbols transmitted by the first subscriber station.

22. The base station as set forth in claim 21, wherein the size N FT block is one of:

1) a Fast Fourier Transform (FFT) block and

     2) a Discrete Fourier Transform (DFT) block, and the size M1 IFT block and the size M2 IFT block are one of;

     1) inverse Fast Fourier Transform (IFFT) blocks and

     2) inverse Discrete Fourier Transform (IDFT) blocks.

23. The base station as set forth in claim 22, wherein the value of N is greater than or equal to the sum of M1 and M2.

24. The base station as set forth in claim 22, wherein the size N FT block generates on at least some of N−

(M1+M2) outputs at least one of;

     1) signaling and control symbols and

     2) user data symbols that have not been FT pre-coded by the first subscriber station.

25. The base station as set forth in claim 22, wherein the first plurality of symbols generated by the size M1 IFT block comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

26. The base station as set forth in claim 25, wherein the second plurality of symbols generated by the size M2 IFT block comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

27. The base station as set forth in claim 22, further comprising a frequency-domain equalizer capable of receiving at least some of the N outputs of the size N FT block corresponding to a pilot signal transmitted by the first subscriber station and using the pilot signal to perform frequency-domain equalization on the M1 outputs of the size N FT block prior to the size M1 IFT operation of the size M1 IFT block.

28. A method for use in base station of a wireless network capable of communicating with subscriber stations according to a multi-carrier protocol, the method comprising the steps of:

receiving incoming radio frequency (RF) signals from the subscriber stations;

down-converting the incoming RF signals to generate a baseband signal;

performing a size N Fourier Transform (FT) operation on the baseband signal to generate N outputs;

performing a size M1 Inverse Fourier Transform (IFT) operation on M1 outputs of the size N FT operation to generate a first plurality of symbols transmitted by a first one of the subscriber stations; and

performing a size M2 Inverse Fourier Transform (IFT) operation on M2 outputs of the size N FT operation to generate a second plurality of symbols transmitted by the first subscriber station.

29. The method as set forth in claim 28, wherein the size N FT operation is one of:

1) a Fast Fourier Transform (FFT) operation and

     2) a Discrete Fourier Transform (DFT) operation, and the size M1 IFT block and the size M2 IFT block are one of;

     1) inverse Fast Fourier Transform (IFFT) operations and

     2) inverse Discrete Fourier Transform (IDFT) operations.

30. The method as set forth in claim 29, wherein the value of N is greater than or equal to the sum of M1 and M2.

31. The method as set forth in claim 29, wherein the size N FT operation generates on at least some of N−

(M1+M2) outputs at least one of;

     1) signaling and control symbols and

     2) user data symbols that have not been FT pre-coded by the first subscriber station.

32. The method as set forth in claim 29, wherein the first plurality of symbols generated by the size M1 IFT operation comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

33. The method as set forth in claim 32, wherein the second plurality of symbols generated by the size M2 IFT operation comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

34. The method as set forth in claim 29, further comprising the steps of:

receiving at least some of the N outputs of the size N FT operation corresponding to a pilot signal transmitted by the first subscriber station; and

using the pilot signal to perform frequency-domain equalization on the M1 outputs of the size N FT operation prior to the size M1 IFT operation.

35. A wireless network comprising a plurality of base stations capable of communicating with subscriber stations according to a multi-carrier protocol, each of the base stations comprising:

down-conversion circuitry capable of receiving incoming radio frequency signals from the subscriber stations and generating therefrom a baseband signal;

a size N Fourier Transform (FT) block capable of receiving the baseband signal on N inputs and performing an FT operation to generate N outputs;

a size M1 Inverse Fourier Transform (IFT) block capable of receiving M1 outputs of the size N FT block and performing a size M1 IFT operation on the M1 outputs to generate a first plurality of symbols transmitted by a first one of the subscriber stations; and

a size M2 Inverse Fourier Transform (IFT) block capable of receiving M2 outputs of the size N FT block and performing a size M2 IFT operation on the M2 outputs to generate a second plurality of symbols transmitted by the first subscriber station.

36. The wireless network as set forth in claim 35, wherein the size N FT block is one of:

1) a Fast Fourier Transform (FFT) block and

     2) a Discrete Fourier Transform (DFT) block, and the size M1 IFT block and the size M2 IFT block are one of;

     1) inverse Fast Fourier Transform (IFFT) blocks and

     2) inverse Discrete Fourier Transform (IDFT) blocks.

37. The wireless network as set forth in claim 36, wherein the value of N is greater than or equal to the sum of M1 and M2.

38. The wireless network as set forth in claim 36, wherein the size N FT block generates on at least some of N−

(M1+M2) outputs at least one of;

     1) signaling and control symbols and

     2) user data symbols that have not been FT pre-coded by the first subscriber station.

39. The wireless network as set forth in claim 36, wherein the first plurality of symbols generated by the size M1 IFT block comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

40. The wireless network as set forth in claim 39, wherein the second plurality of symbols generated by the size M2 IFT block comprise at least one of 1) user data symbols and 2) signaling and control symbols transmitted by the first subscriber station.

41. The wireless network as set forth in claim 36, further comprising a frequency-domain equalizer capable of receiving at least some of the N outputs of the size N FT block corresponding to a pilot signal transmitted by the first subscriber station and using the pilot signal to perform frequency-domain equalization on the M1 outputs of the size N FT block prior to the size M1 IFT operation of the size M1 IFT block.