Preamble detection with unknown channel

• US 8,442,166 B2
• Filed: 04/30/2012
• Issued: 05/14/2013
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Lee, Jungwon, Lou, Hui-Ling
• Primary Examiner(s): PATEL, DHAVAL V
• Application Number:
  US13/460,109
• Publication Number:
  US 20120213316A1
• Time in Patent Office: 379 Days
• Field of Search: 375/260, 375/267, 375/295, 375/296, 375/297, 375/340, 375/343, 375/346, 375/347, 375/349, 375/350, 370/203, 370/204, 370/205, 370/206, 370/207, 370/208, 370/209, 370/210
• US Class Current: 375/343
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

A system including a control module and a correlation module. The control module partitions a total number of subcarriers, in a received signal, into a predetermined number of bands. The correlation module generates a plurality of correlation values for a plurality of preamble sequences. A correlation value for a preamble sequence is generated by correlating symbols in each band with corresponding symbols in the preamble sequence to generate correlations for each band, adding the correlations generated for a respective band to generate a sum for each band, and adding the sums generated for all the bands. The control module select a largest correlation value from the plurality of correlation values and determine that one of the preamble sequences is detected in the received signal in response to the largest correlation value being greater than or equal to a predetermined threshold.

Claims

1. A system, comprising:

a control module configured to partition a total number of subcarriers, in a received signal, into a predetermined number of bands, wherein each band includes a predetermined number of subcarriers, and wherein a product of the number of subcarriers in each band and the number of bands equals the total number of subcarriers; and

a correlation module configured to generate a plurality of correlation values for a plurality of preamble sequences, wherein a correlation value for a preamble sequence is generated by

correlating symbols in each band with corresponding symbols in the preamble sequence to generate correlations for each band,

adding the correlations generated for a respective band to generate a sum for each band, and

adding the sums generated for all the bands,

wherein the control module is further configured to

select a largest correlation value from the plurality of correlation values, and

determine that one of the preamble sequences is detected in the received signal in response to the largest correlation value being greater than or equal to a predetermined threshold.

2. The system of claim 1, wherein the predetermined threshold is a function of signal strength of the received signal.

3. The system of claim 1, wherein the control module is configured to partition the total number of subcarriers in the received signal into the predetermined number of bands in response to a channel gain of the subcarriers being not the same for all of the subcarriers.

4. The system of claim 1, wherein the control module is configured to identify a segment of a base station that transmitted the received signal based on the one of the preamble sequences.

5. The system of claim 1, wherein:

each of the preamble sequences is different from others of the preamble sequences; and

the preamble sequences have a cross-correlation value of less than or equal to a second predetermined threshold.

6. The system of claim 5, wherein the second predetermined threshold is less than approximately 0.2 for an orthogonal frequency domain multiplexing (OFDM) method using a 1024 fast Fourier transform (FFT) mode.

7. The system of claim 1, wherein the preamble sequences are stored in one of the correlation module and the control module.

8. The system of claim 1, wherein the subcarriers have a random channel phase.

9. The system of claim 1, wherein the received signal includes a fractional carrier frequency offset (CFO).

10. The system of claim 1, wherein the received signal includes an integer carrier frequency offset (CFO).

11. A method, comprising:

partitioning a total number of subcarriers in a received signal into a predetermined number of bands, wherein each band includes a predetermined number of subcarriers, and wherein a product of the number of subcarriers in each band and the number of bands equals the total number of subcarriers;

generating a plurality of correlation values for a plurality of preamble sequences, wherein a correlation value for a preamble sequence is generated by

correlating symbols in each band with corresponding symbols in the preamble sequence to generate correlations for each band,

adding the correlations generated for a respective band to generate a sum for each band, and

adding the sums generated for all the bands;

selecting a largest correlation value from the plurality of correlation values; and

determining that one of the preamble sequences is detected in the received signal in response to the largest correlation value being greater than or equal to a predetermined threshold.

12. The method of claim 11, wherein the predetermined threshold is a function of signal strength of the received signal.

13. The method of claim 11, further comprising partitioning the total number of subcarriers in the received signal into the predetermined number of bands in response to a channel gain of the subcarriers being not the same for all of the subcarriers.

14. The method of claim 11, further comprising identifying a segment of a base station that transmitted the received signal based on the one of the preamble sequences.

15. The method of claim 11, wherein:

each of the preamble sequences is different from others of the preamble sequences; and

the preamble sequences have a cross-correlation value of less than or equal to a second predetermined threshold.

16. The method of claim 15, wherein the second predetermined threshold is less than approximately 0.2 for an orthogonal frequency domain multiplexing (OFDM) method using a 1024 fast Fourier transform (FFT) mode.

17. The method of claim 11, further comprising storing the preamble sequences.

18. The method of claim 11, wherein the subcarriers have a random channel phase.

19. The method of claim 11, wherein the received signal includes a fractional carrier frequency offset (CFO).

20. The method of claim 11, wherein the received signal includes an integer carrier frequency offset (CFO).