Method of generating binary offset carrier correlation function based on partial correlation functions, apparatus for tracking binary offset carrier signal, and spread spectrum signal receiver system using the same

• US 9,813,108 B2
• Filed: 05/20/2016
• Issued: 11/07/2017
• Est. Priority Date: 10/29/2013
• Status: Active Grant

• Current Assignee: SungKyunKwan University's Research & Business Foundation (SungKyunKwan University)
• Original Assignee: SungKyunKwan University's Research & Business Foundation (SungKyunKwan University)
• Inventors: Chae, Keun Hong, Yoon, Seok Ho
• Primary Examiner(s): Burd, Kevin M
• Application Number:
  US15/160,187
• Publication Number:
  US 20160269073A1
• Time in Patent Office: 536 Days
• Field of Search: 375130, 375140, 375147, 375150
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 2001/70706 using a code tracking loop, e.g. a delay locked loop
• CPC Class Codes: H04B 2201/707 relating to direct sequence modulation

Abstract

A method of generating a BOC correlation function based on partial correlation functions, an apparatus for tracking a BOC signal, and a spread spectrum signal receiver system using the same are disclosed herein. The apparatus includes a frequency offset compensation unit, a local code generation unit, a mixer, a delay lock loop (DLL), a phase lock loop (PLL), and a data extraction unit. The frequency offset compensation unit outputs a compensated received signal with respect to a received signal. The local code generation unit generates a delay-compensated local code based on a code delay value. The mixer mixes the delay-compensated local code with the frequency offset-compensated received signal. The DLL repeatedly tracks and calculates a code delay value. The PLL repeatedly calculates a carrier frequency compensation value. The data extraction unit extracts spreading data from a mixture of the delay-compensated local code and the compensated received signal.

Claims

1. A delay lock loop (DLL) to track a code delay phase value for a local code to be correlated with a received BOC-modulated signal in which N pulses successively occur in a single period T_c of a spreading code chip in a spread spectrum signal receiver system, the DLL comprising:

a processor configured to;

generate an early and late delayed received signal pair B(t+τ

+Δ

/2) and B(t+τ

−

Δ

/2), based on phase delay τ and

a delay value difference Δ

, with respect to a received signal pulse train of a received signal B(t), wherein the B(t+τ

+Δ

/2) is an early signal and the B(t+τ

−

Δ

/2) is a late signal,

generate N early partial correlation functions S_m(τ

+Δ

/2) (where 0≦

m≦

N−

1) and N late partial correlation functions S_m(τ

−

Δ

/2) by performing an auto-correlation operation on the early and late delayed received signal pair B(t+τ

+Δ

/2) and B(t+τ

−

Δ

/2) with respect to a total time T(0≦

t≦

T),

obtain an early intermediate correlation function R₀(τ

+Δ

/2;

a) by performing an elimination operation on an early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) obtained by combining first and last early partial correlation functions S₀(τ

+Δ

/2) and S_N-1(τ

+Δ

/2) based on a main peak shape parameter a such that only a main peak is left, and generate an early main correlation function R_proposed(τ

+Δ

/2;

a) by superposing results obtained by additionally performing an elimination operation on the early intermediate correlation function R₀(τ

+Δ

/2;

a) and each of the early partial correlation functions S_m(τ

+Δ

/2),

obtain a late intermediate correlation function R₀(τ

−

Δ

/2;

a) by performing an elimination operation on a late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) obtained by combining first and last late partial correlation functions S₀(τ

−

Δ

/2) and S_N-1(τ

−

Δ

/2) based on a main peak shape parameter a, such that only a main peak is left, and generate a late main correlation function R_proposed(τ

−

Δ

/2;

a) by superposing results obtained by additionally performing an elimination operation on the late intermediate correlation function R₀(τ

−

Δ

/2;

a) and each of the late partial correlation functions S_m(τ

−

Δ

/2), and

determine a phase delay τ

for the received signal based on a discrimination output of a discrimination function based on values of the early and late main correlation functions, and

output the determined phase delay τ

,

wherein the elimination operation is related to an algebraic relation in which when real numbers x and y are xy≦

0, |x|+|y|−

|x−

y|=0.

2. The DLL of claim 1, wherein the N early partial correlation functions S_m(τ

+Δ

/2) or the N late partial correlation functions S_m(τ

−

Δ

/2), when the received signal B(t) is viewed as a sum of N partial received signals obtained by superposing an m-th (0≦

m≦

N−

1) pulse of N pulses present within each chip period T_c on the other m-th pulses, are obtained by performing an auto-correlation operation on each of the N partial received signals based on the following equation;

3. The DLL of claim 1, wherein the early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) is generated such that the early sub-correlation function pair is symmetrical with respect to a vertical axis, in response to the early sub-correlation function pair overlapping the late sub-correlation function pair, or the late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) is generated such that the late sub-correlation function pair is symmetrical with respect to the vertical axis, in response to the early sub-correlation function pair overlapping the late sub-correlation function pair.

4. The DLL of claim 1, wherein the early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) or the late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) is generated based on the following equation;

5. The DLL of claim 1, wherein the early intermediate correlation function R₀(τ

+Δ

/2;

a) or the late intermediate correlation function R₀(τ

−

Δ

/2;

a) is generated based on the following equation;

R₀(τ

;

a)=|T₁(τ

;

a)|+|T₂(τ

;

a)|−

|T₁(τ

;

a)−

T₂(τ

;

a)|.

6. The DLL of claim 1, wherein the early main correlation function R_proposed(τ

+Δ

/2;

a) or the late main correlation function R_proposed(τ

−

Δ

/2;

a) is generated based on the following equation;

7. The DLL of claim 6, wherein each of the early main correlation function R_proposed(τ

+Δ

/2;

a) and the late main correlation function R_proposed(τ

−

Δ

/2;

a) is generated to comprise a waveform comprising a main peak comprising a height of 2 and a base width of

8. The DLL of claim 1, wherein the discrimination function is selected to determine whether a main correlation function value based on the phase delay τ

is located at an apex of the main peak based on the discrimination output.

9. The DLL of claim 8, wherein the discrimination function D(τ

) is defined as the following equation;

10. The DLL of claim 9, wherein the code delay phase value for the local code is determined to be a value of the phase delay τ

, in response to zero crossing of the discrimination function D(τ

) being detected.

11. A BOC signal tracking method to track a code delay phase value for a local code to be correlated with a received BOC-modulated signal in which N pulses successively occur in a single period T_c of a spreading code chip in a spread spectrum signal receiver system, the method comprising:

generating an early and late delayed received signal pair B(t+τ

+Δ

/2) and B(t+τ

−

Δ

/2), based on phase delay τ and

a delay value difference Δ

, with respect to a received signal pulse train of a received signal B(t), wherein the B(t+τ

+Δ

/2) is an early signal and the B(t+τ

−

Δ

/2) is a late signal;

generating N early partial correlation functions S_m(τ

+Δ

/2) (where 0≦

m≦

N−

1) and N late partial correlation functions S_m(τ

−

Δ

/2) by performing an auto-correlation operation on the early and late mixed signal pair B(t+τ

+Δ

/2) and B(t+τ

−

Δ

/2) with respect to a total time T(0≦

t≦

T);

obtaining an early intermediate correlation function R₀(τ

+Δ

/2;

a) by performing an elimination operation on an early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) obtained by combining first and last early partial correlation functions S₀(τ

+Δ

/2) and S_N-1(τ

+Δ

/2) based on a main peak shape parameter a, such that only a main peak is left, and generating an early main correlation function R_proposed(τ

+Δ

/2;

a) by superposing results obtained by additionally performing an elimination operation on the early intermediate correlation function R₀(τ

+Δ

/2;

a) and each of the early partial correlation functions S_m(τ

+Δ

/2);

obtaining a late intermediate correlation function R₀(τ

−

Δ

/2;

a) by performing an elimination operation on a late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) obtained by combining first and last late partial correlation functions S₀(τ

−

Δ

/2) and S_N-1(τ

−

Δ

/2) based on a given main peak shape parameter a such that only a main peak is left, and generating a late main correlation function R_proposed(τ

−

Δ

/2;

a) by superposing results obtained by additionally performing an elimination operation on the late intermediate correlation function R₀(τ

−

Δ

/2;

a) and each of the late partial correlation functions S_m(τ

−

Δ

/2); and

determining a phase delay τ

for the received signal based on a discrimination output of a discrimination function based on values of the early and late main correlation functions,

wherein the elimination operation is an operation related to an algebraic relation in which when real numbers x and y are xy≦

0, |x|+|y|−

|x−

y|=0.

12. The BOC signal tracking method of claim 11, wherein the N early partial correlation functions S_m(τ

+Δ

/2) or the N late partial correlation functions S_m(τ

−

Δ

/2), when the received signal B(t) is viewed as a sum of N partial received signals obtained by superposing an m-th (0≦

m≦

N−

1) pulse of N pulses present within each chip period T_c on the other m-th pulses, are obtained by performing an auto-correlation operation on each of the N partial received signals based on the following equation;

13. The BOC signal tracking method of claim 11, wherein the early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) is generated such that the early sub-correlation function pair is symmetrical with respect to a vertical axis, in response to the early sub-correlation function pair overlapping the late sub-correlation function pair, or the late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) is generated such that the late sub-correlation function pair is symmetrical with respect to a vertical axis, in response to the early sub-correlation function pair overlapping the late sub-correlation function pair.

14. The BOC signal tracking method of claim 11, wherein the early sub-correlation function pair T₁(τ

+Δ

/2;

a) and T₂(τ

+Δ

/2;

a) or the late sub-correlation function pair T₁(τ

−

Δ

/2;

a) and T₂(τ

−

Δ

/2;

a) is generated based on the following equation;

15. The BOC signal tracking method of claim 11, wherein the early intermediate correlation function R₀(τ

+Δ

/2;

a) or the late intermediate correlation function R₀(τ

−

Δ

/2;

a) is generated based on the following equation;

R₀(τ

;

a)=|T₁(τ

;

a)|+|T₂(τ

;

a)|−

|T₁(τ

;

a)−

T₂(τ

;

a)|.

16. The BOC signal tracking method of claim 11, wherein the early main correlation function R_proposed(τ

+Δ

/2;

a) or the late main correlation function R_proposed(τ

−

Δ

/2;

a) is generated based on the following equation;

17. The BOC signal tracking method of claim 16, wherein each of the early main correlation function R_proposed(τ

+Δ

/2;

a) and the late main correlation function R_proposed(τ

−

Δ

/2;

a) is generated to comprise a waveform comprising a main peak comprising a height of 2 and a base width of

18. The BOC signal tracking method of claim 11, wherein the discrimination function is selected to determine whether a main correlation function value based on the phase delay τ

is located at an apex of the main peak based on the discrimination output.

19. The BOC signal tracking method of claim 18, wherein the discrimination function D(τ

) is defined as the following equation;

20. The BOC signal tracking method of claim 19, wherein the code delay phase value for the local code is determined to be a value of the phase delay τ

, in response to zero crossing of the discrimination function D(τ

) being detected.