Method and apparatus for overlaying two CDMA systems on the same frequency bandwidth

• US 20050122917A1
• Filed: 01/19/2005
• Published: 06/09/2005
• Est. Priority Date: 09/13/1999
• Status: Active Grant

• Current Assignee: Edward G. Tiedemann Jr
• Original Assignee: Edward G. Tiedemann Jr
• Inventors: Tiedemann, Edward G. Jr.
• Granted Patent: US 7,212,508 B2
• Time in Patent Office: Days
• US Class Current: 370/300
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04B 7/2696 Over the air autonomous synchronisation, e.g. by monitoring network activity H04B7/2693 takes precedence
• CPC Class Codes: H04J 13/004 Orthogonal

Abstract

In order to align the timing of an overlay base station to the timing of an existing base station, a sync unit is introduced into the system. The sync unit has a first receiver configured to receive a first signal, the first signal having a first CDMA channelization. The first receiver is configured to produce an indication of a timing of the first signal. The sync unit also has a second receiver configured to receive a second signal, the second signal having a second CDMA channelization. The second receiver is configured to produce an indication of a timing of the second signal. The sync unit also has a time error detection unit configured to compare the timing of the first signal and the timing of the second signal to determine a relative timing offset thereof.

Claims

1. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:

transmitting a first signal using a first CDMA channelization;

transmitting a second signal using a second CDMA channelization, wherein said first and second CDMA channelization share at least a portion of a common frequency spectrum and wherein said first signal and said second signal are transmitted into a common coverage area;

obtaining signal energy corresponding to said first signal;

obtaining signal energy corresponding to said second signal;

comparing a phase of said first signal to a phase of said second signal to generate a phase error indication based upon said obtained signal energies; and

adjusting a phase at which said second signal is transmitted in response to said phase error indication.

2. The method of claim 1, wherein said first signal is a pilot signal.

3. The method of claim 1, wherein steps of transmitting said first and second signals comprise the step of transmitting said first and second signals over a first antenna.

4. The method of claim 3, wherein steps of obtaining signal energy corresponding to said first and second signals comprise the step of receiving said first and second signals over a second antenna.

5. The method of claim 1, wherein step of obtaining signal energy corresponding to said second signal comprises the step of using a coupler.

6. The method of claim 1, wherein said second CDMA channelization has a wider spectrum than said first CDMA channelization.

7. The method of claim 1, wherein said first CDMA channelization has a wider spectrum than said second CDMA channelization.

8. The method of claim 1, wherein said second signal is a remote unit specific signal.

9. The method of claim 1, wherein said second signal is an information signal.

10. The method of claim 1, wherein said second signal is a broadcast signal.

11. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:

transmitting a first signal using a first CDMA channelization;

transmitting a second signal using a second CDMA channelization, wherein said first and second CDMA channelization share at least a portion of a common frequency spectrum and wherein said first signal and said second signal are transmitted into a common coverage area;

obtaining signal energy corresponding to said first signal;

obtaining signal energy corresponding to said second signal;

comparing a timing of said first signal to a timing of said second signal to generate a timing error indication based upon said obtained signal energies; and

adjusting a timing at which said second signal is transmitted in response to said timing error indication.

12. The method of claim 11, wherein said first signal is a pilot signal.

13. The method of claim 11, wherein steps of transmitting said first and second signals comprise the step of transmitting said first and second signals over a first antenna.

14. The method of claim 13 wherein steps of obtaining signal energy corresponding to said first and second signals comprise the step of receiving said first and second signals over a second antenna.

15. The method of claim 11, wherein step of obtaining signal energy corresponding to said second signal comprises the step of using a coupler.

16. The method of claim 11 wherein said second CDMA channelization has a wider spectrum than said first CDMA channelization.

17. The method of claim 11 wherein said first CDMA channelization has a wider spectrum than said second CDMA channelization.

18. The method of claim 11 wherein said second signal is a remote unit specific signal.

19. The method of claim 11 wherein said second signal is an information signal.

20. The method of claim 11, wherein said second signal is a broadcast signal.

21. A CDMA system comprising:

a first base station configured to transmit a first signal using a first CDMA channelization;

a second base station configured to transmit a second signal using a second CDMA channelization; and

a sync unit configured to receive said first signal and said second signal and configured to determine a relative phase difference therebetween;

wherein said second base station is further configured to adjust a phase at which said second signal is transmitted based upon said relative phase difference; and

wherein said first signal is transmitted using a first CDMA channelization and said second signal is transmitted using a second CDMA channelization.

22. The CDMA system of claim 21, further comprising a first antenna coupled to said first and second base stations and configured to emit said first signal and said second signal.

23. The CDMA system of claim 21 wherein said first signal is a pilot signal and said second signal is an information signal.

24. The CDMA system of claim 21 wherein said first signal is transmitted using a first CDMA channelization and said second signal is transmitted using a second CDMA channelization.

25. A CDMA system comprising:

a first base station configured to transmit a first signal using a first CDMA channelization;

a second base station configured to transmit a second signal using a second CDMA channelization; and

a sync unit configured to receive said first signal and said second signal and configured to determine a relative timing difference therebetween;

wherein said second base station is further configured to adjust a timing at which said second signal is transmitted based upon said relative timing difference; and

wherein said first signal is transmitted using a first CDMA channelization and said second signal is transmitted using a second CDMA channelization.