Method and apparatus for adjusting reference frequency

• US 8,289,945 B2
• Filed: 06/05/2008
• Issued: 10/16/2012
• Est. Priority Date: 06/06/2007
• Status: Active Grant

• Current Assignee: Qisda Corporation
• Original Assignee: Qisda Corporation
• Inventors: Liao, Xue-Jian, Lin, Kuo-Chuan
• Primary Examiner(s): TRAN, PHUC H
• Application Number:
  US12/133,853
• Publication Number:
  US 20080307023A1
• Time in Patent Office: 1,594 Days
• Field of Search: 370/350, 370/503, 370/510
• US Class Current: 370/350
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols

Abstract

The invention discloses a method for adjusting a reference frequency. First, a training signal is received based on the reference frequency. Then, a target region of the training signal is divided by an original training sequence so that a quotient polynomial is generated. Afterward, the quotient polynomial is divided by a predetermined polynomial so that a remainder polynomial is generated. Finally, the reference frequency is adjusted based on the remainder polynomial.

Claims

1. A method for adjusting a reference frequency, applied to a receiving terminal, comprising steps of:

(a) receiving a training signal based on the reference frequency at the receiving terminal;

(b) dividing an original training sequence [T(X)] into a target region of the training signal to generate a quotient polynomial;

(c) dividing a predetermined polynomial [H(X)] into the quotient polynomial to generate a remainder polynomial; and

(d) adjusting the reference frequency based on the remainder polynomial.

2. The method of claim 1, wherein the original training sequence [T(X)] is a polynomial with binary coefficient.

3. The method of claim 1, wherein a product of the original training sequence [T(X)] and the predetermined polynomial [H(X)] is (1+X^N).

4. The method of claim 1, wherein the training signal comprises a plurality of shifted training sequences [T^(d)(X)], and each of the plurality of shifted training sequences [T^(d)(X)] is respectively related to the original training sequence [T(X)].

5. The method of claim 4, wherein the plurality of shifted training sequences [T^(d)(X)] is comprised in the training signal under a cyclic mode.

6. The method of claim 1, wherein a length of the target region is equal to that of the original training sequence [T(X)].

7. The method of claim 1, wherein the step (d) comprises steps of:

(d1) shifting the training signal and repeating the steps (b) and (c) till N remainder polynomials are generated, wherein N is a positive integer; and

(d2) adjusting the reference frequency based on the N remainder polynomials.

8. The method of claim 7, wherein the step (d2) comprises steps of:

(d21) selecting M candidate polynomials from the N remainder polynomials, wherein M is a positive integer smaller than or equal to N, and each of the M candidate polynomials is a monomial;

(d22) analyzing the M candidate polynomials to determine a target polynomial; and

(d23) adjusting the reference frequency based on the target polynomial.

9. The method of claim 8, wherein the step (d22) is performed to analyze the M candidate polynomials through statistics.

10. The method of claim 1, further comprises step of:

transmitting an original training signal from a transmitting terminal by orthogonal frequency division multiplexing;

wherein the original training signal is corresponding to the training signal received in step (a).

11. An apparatus for adjusting a reference frequency, comprising:

a receiving module for receiving a training signal based on the reference frequency;

a first dividing module for dividing an original training sequence [T(X)] into a target region of the training signal to generate a quotient polynomial;

a second dividing module for dividing a predetermined polynomial [H(X)] into the quotient polynomial to generate a remainder polynomial; and

an adjusting module for adjusting the reference frequency based on the remainder polynomial.

12. The apparatus of claim 11, wherein the original training sequence [T(X)] is a polynomial with binary coefficient.

13. The apparatus of claim 11, wherein the product of the original training sequence [T(X)] and the predetermined polynomial [H(X)] is (1+X^N).

14. The apparatus of claim 11, wherein the training signal comprises a plurality of shifted training sequences [T^(d)(X)], and each of the plurality of shifted training sequences [T^(d)(X)] is respectively related to the original training sequence [T(X)].

15. The apparatus of claim 14, wherein the plurality of shifted training sequences [T^(d)(X)] is comprised in the training signal under a cyclic mode.

16. The apparatus of claim 11, wherein a length of the target region is equal to that of the original training sequence [T(X)].

17. The apparatus of claim 11, wherein the adjusting module comprises:

a shifted unit for shifting the training signal and repeating the first and the second dividing modules till N remainder polynomials are generated, wherein N is a positive integer; and

an adjusting unit for adjusting the reference frequency based on the N remainder polynomials.

18. The apparatus of claim 17, wherein the adjusting unit comprises:

a selecting device for selecting M candidate polynomials from the N remainder polynomials, wherein M is a positive integer smaller than or equal to N, and each of the M candidate polynomials is a monomial;

an analyzing device for analyzing the M candidate polynomials to determine a target polynomial; and

an adjusting device for adjusting the reference frequency based on the target polynomial.

19. The apparatus of claim 18, wherein the analyzing device analyzes the M candidate polynomials through statistics.

20. The apparatus of claim 11, further comprising:

a transmitting module for transmitting an original training signal by orthogonal frequency division multiplexing;

wherein the original training signal is corresponding to the training signal received by the receiving module.