Method and apparatus for adjusting frequencies of radio communication devices

• US 20070155342A1
• Filed: 01/04/2006
• Published: 07/05/2007
• Est. Priority Date: 01/04/2006
• Status: Abandoned Application

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Yang, Ganning, Tsai, Jeng
• Application Number:
  US11/326,246
• Publication Number:
  US 20070155342A1
• Time in Patent Office: Days
• US Class Current: 455/75
• CPC Class Codes: H03J 2200/02 Algorithm used as input for AFC action alignment receiver
• CPC Class Codes: H03J 7/02 Automatic frequency control H03J7/18 takes precedence
• CPC Class Codes: H04W 56/0035 detecting errors in frequency or phase

Abstract

Methods and systems with different control rates for uplink and downlink oscillators. The method comprises obtaining the frequency offsets between a receiver oscillator frequency and a carrier frequency of received signals, adjusting the receiver oscillator frequency at a first rate according to the frequency offsets, and adjusting the transmitter oscillator at a second rate according to the first rate. The receiver oscillator frequency is adjusted according to filtered frequency offsets, while the transmitter oscillator frequency is adjusted according to the frequency offsets and smoothed frequency offsets.

Claims

1. A method for adjusting a radio communication device comprising a receiver oscillator and a transmitter oscillator, the method comprising:

obtaining the frequency offset between a first frequency and a carrier frequency of received signals, wherein the first frequency is generated by the receiver oscillator;

adjusting the first frequency at a first rate according to the frequency offset, wherein the first rate is a change of a frequency within a time unit; and

adjusting the transmitter oscillator at a second rate according to the first rate, wherein the first rate and the second rate are different.

2. The method as claimed in claim 1, wherein adjusting the first frequency comprises smoothing the changes of the first frequency to obtain a first adjusting signal to control the first frequency.

3. The method as claimed in claim 1, wherein adjusting the transmitter oscillator comprises:

smoothing the first adjusting signal to obtain a second adjusting signal; and

controlling the transmitter oscillator according to the second adjusting signal.

4. The method as claimed in claim 1, further comprising adjusting the transmitter oscillator at a second rate according to the first rate and the frequency offset.

5. The method as claimed in claim 1, wherein the first rate is faster than the second rate.

6. The method as claimed in claim 1, wherein the receiver oscillator is a downlink receiving oscillator, and the transmitter oscillator is an uplink transmitting oscillator.

7. An integrated circuit installed in a radio communication device, for communicating with a corresponding radio communication device, the integrated circuit comprising:

a down-converter comprising a receiver oscillator, generating a first frequency, and converting first signals into a plurality of second signals, wherein the first signals has a carrier frequency and are transmitted from the corresponding radio communication device;

a transmitter oscillator generating a transmitting frequency, and transmitting third signals with the transmitting frequency to the corresponding communication device;

a frequency offset estimating module obtaining the carrier frequency of the first signals according to the plurality of second signals, and calculating a frequency offset between the first frequency and the carrier frequency;

a first smoothing module generating a first adjusting signal according to the frequency offsets, wherein the first adjusting signal is sent to adjust the first frequency at a first rate, and the first rate is a change of a frequency within a time unit; and

a second smoothing module receiving the first adjusting signal to generate a second adjusting signal, wherein the second adjusting signal is sent to adjust the transmitting frequency at a second rate, and the first rate and the second rate are different.

8. The integrated circuit as claimed in claim 7, wherein the second smoothing module generates the second adjusting signal according to the frequency offset and the first rate.

9. The integrated circuit as claimed in claim 7, wherein the first rate is faster then the second rate.

10. The integrated circuit as claimed in claim 7, wherein the first smoothing module is a loop filter.

11. The integrated circuit as claimed in claim 7, wherein the receiver oscillator is a downlink receiving oscillator, and the transmitter oscillator is an uplink transmitting oscillator.

12. A radio communication device for communicating with a corresponding radio communication device, comprising:

a receiver oscillator generating a first frequency, and converting first signals into a plurality of second signals, wherein the first signal has a carrier frequency and are transmitted from the corresponding radio communication device;

a transmitter oscillator generating a transmitting frequency, and transmitting third signals with the transmitting frequency to the corresponding communication device; and

a processing unit, obtaining the carrier frequency of the first signals according to the plurality of second signals, calculating a frequency offsets between the first frequency and the carrier frequency, generating a first adjusting signal according to the calculated frequency offsets, wherein the first adjusting signal is sent to adjust the first frequency at a first rate, and receiving the first adjusting signal to generate a second adjusting signal, wherein the first rate is a change of a frequency within a time unit, and the second adjusting signal is send to adjust the transmitting frequency at a second rate, and the first rate and the second rate are different.

13. The radio communication device as claimed in claim 12, wherein the processing unit is a digital signal processor.

14. The radio communication device as claimed in claim 13, wherein the digital signal processor executes the programs comprising:

an frequency offset estimating module obtaining the carrier frequency of the first signals according to the plurality of second signals, and estimating the frequency offsets between the first frequency and the carrier frequency;

a first smoothing module generating a first adjusting signal according to the estimated frequency offset, wherein the first adjusting signal is sent to adjust the first frequency at a first rate, wherein the first rate is a change of a frequency within a time unit; and

a second smoothing module receiving the first adjusting signal to generate a second adjusting signal, wherein the second adjusting signal is sent to adjust the transmitting frequency at a second rate, and the first and second rate are different.

15. The radio communication device as claimed in claim 14, wherein the second smoothing module generates the second adjusting signal according to the frequency offsets and the first rate.

16. The radio communication device as claimed in claim 12, wherein the first rate is faster then the second rate.

17. The first radio communication device as claimed in claim 14, wherein the first smoothing module is a loop filter.

18. The first radio communication device as claimed in claim 12, wherein the receiver oscillator is a downlink receiving oscillator, and the transmitter oscillator is an uplink transmitting oscillator.