AFC control apparatus and method in mobile communication system and mobile communication equipment using the apparatus and method

• US 20010004373A1
• Filed: 12/13/2000
• Published: 06/21/2001
• Est. Priority Date: 12/15/1999
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hirata, Masaru
• Granted Patent: US 6,816,540 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H03J 7/02 Automatic frequency control H03J7/18 takes precedence

Abstract

An AFC control apparatus in mobile communication equipment includes a depreading unit, first integrator, and control section. A despreading section despreads the reception signal. The first integrator integrates despread outputs obtained by despreading, of pilot symbols contained in a pilot channel of the reception signal, N (N is a number of 2 or more) consecutive first symbols and N second symbols succeeding the N first symbols, and generates first and second integral outputs. The control section detects any phase shift amount between the first and second integral outputs and controls the frequency of the local signal in accordance with the detected phase shift amount. An AFC control method and mobile communication equipment having the above apparatus and method are also disclosed.

Claims

1. An AFC control apparatus in mobile communication equipment, which receives a spread signal obtained by phase-modulating a baseband signal, multiplies the reception signal with a local signal to obtain a baseband signal, and despreads the baseband signal, comprising:

depreading means for despreading the reception signal;

first integrating means for integrating despread outputs obtained by despreading, of pilot symbols contained in a pilot channel of the reception signal, N (N is a number of not less than

     2) consecutive first symbols and N second symbols succeeding the N first symbols, and generating first and second integral outputs; and

control means for detecting a phase shift amount between the first and second integral outputs and controlling a frequency of the local signal in accordance with the detected phase shift amount.

2. An apparatus according to

claim 1

, wherein said apparatus further comprises second integrating means for dividing a despread output of one symbol of the reception signal from said despreading means and integrating the divided despread outputs, and said control means detects a phase shift amount between the divided integral outputs from said second integrating means and performs the frequency control when the phase shift amount is larger than a predetermined threshold value.

3. An apparatus according to

claim 2

, wherein when the phase shift amount is less than the threshold value, said control means detects a phase shift amount between the first and second integral outputs and performs the frequency control.

4. An apparatus according to

claim 2

or

3

, wherein one symbol of the reception signal comprises a pilot symbol contained in the pilot channel.

9. Mobile communication equipment using an AFC control apparatus defined in any one of

claims 1

to

4

.

11. Mobile communication equipment according to

claim 9

, wherein said equipment employs a CDMA communication scheme.

5. An AFC control method in mobile communication equipment, which receives a spread signal obtained by phase-modulating a baseband signal, multiplies the reception signal with a local signal to obtain a baseband signal, and despreads the baseband signal, comprising:

the depreading step of despreading the reception signal;

the first integrating step of integrating despread outputs obtained by despreading, of pilot symbols contained in a pilot channel of the reception signal, N (N is a number of not less than

     2) consecutive first symbols and N second symbols succeeding the N first symbols, and generating first and second integral outputs in the despreading step; and

the control step of detecting a phase shift amount between the first and second integral outputs and controlling a frequency of the local signal in accordance with the detected phase shift amount.

6. A method according to

claim 5

, wherein said method further comprises the second integrating step of dividing a despread output of one symbol of the reception signal from the despreading step and integrating the divided despread outputs, and the control step comprises detecting a phase shift amount between the divided integral outputs from the second integrating step and performing the frequency control when the phase shift amount is larger than a predetermined threshold value.

7. A method according to

claim 6

, wherein when the phase shift amount is less than the threshold value, the control step comprises detecting a phase shift amount between the first and second integral outputs and performing the frequency control.

10. Mobile communication equipment using an AFC control method defined in any one of

claims 5

to

8

.

12. Mobile communication equipment according to

claim 10

, wherein said equipment employs a CDMA communication scheme.

8. An AFC control method in mobile communication equipment, which receives a spread signal obtained by phase-modulating a baseband signal, multiplies the reception signal with a local signal to obtain a baseband signal, and despreads the baseband signal, comprising:

the depreading step of despreading the reception signal in response to power-on;

the step of dividing a despread output of one symbol of the reception signal in the despreading step and integrating the divided despread outputs;

the step of detecting a phase shift amount between the divided integral outputs in the integrating step and performing the frequency control;

the step of, when the phase shift amount is less than a predetermined threshold value, integrating despread outputs obtained by despreading, of pilot symbols contained in a pilot channel of the reception signal, N (N is a number of not less than

     2) consecutive first symbols and N second symbols succeeding the N first symbols, and generating first and second integral outputs; and

the control step of detecting a phase shift amount between the first and second integral outputs and controlling a frequency of the local signal in accordance with the detected phase shift amount.