Uplink signal detection in RF repeaters

• US 8,223,821 B2
• Filed: 06/25/2009
• Issued: 07/17/2012
• Est. Priority Date: 06/25/2009
• Status: Expired due to Fees

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Hannan, Ariful, Carlson, John
• Primary Examiner(s): Ha, Dac
• Application Number:
  US12/491,371
• Publication Number:
  US 20100329311A1
• Time in Patent Office: 1,118 Days
• Field of Search: 375/150, 375/152, 375/211, 375/214, 375/219, 375/324, 375/340, 375/343, 375/345
• US Class Current: 375/211
• CPC Class Codes: H04B 1/70718 with asynchronous demodulation, i.e. not requiring code synchronisation
• CPC Class Codes: H04B 7/15535 Control of relay amplifier gain amplifier gain control in general H03G3/00; gain control reducing self - or loop interference H04B7/15578

Abstract

A method for detecting an IS-95 signal without knowledge of a spreading code for the IS-95 signal is provided. A received baseband signal is rotated through a plurality of phase-shifts. For each phase-shifted baseband signal, an in-phase component or a quadrature component of the phase-shifted baseband signal is realigned. The in-phase and quadrature components are multiplied by a PN short code to partially despread the components. The partially despread in-phase and quadrature components are multiplied and integrated. The integrated despread in-phase and quadrature components are compared to a threshold value. In response to exceeding the threshold value, the received baseband signal is identified as an IS-95 signal. The method may be implemented on a repeater for repeating signals between multiple sources.

Claims

1. A method for detecting an IS-95 signal without knowledge of a spreading code for the IS-95 signal, the method comprising:

rotating a received baseband signal through a plurality of phase-shifts;

for each phase-shifted baseband signal;

realigning an in-phase component or a quadrature component of the phase-shifted baseband signal;

multiplying the in-phase and quadrature components by a PN short code to partially despread the components;

multiplying the partially despread in-phase and quadrature components; and

integrating the multiplied partially despread in-phase and quadrature components;

comparing the integrated despread in-phase and quadrature components to a threshold value; and

in response to exceeding the threshold value, identifying the received baseband signal as an IS-95 signal.

2. The method of claim 1, wherein the PN short code is derived from a current GPS time of day.

3. The method of claim 1, further comprising:

obtaining an integrated value for each of the phase-shifts in the plurality of phase-shifts; and

evaluating each phase shift to determine a maximum magnitude of the integrated value among each of the plurality of phase shifts.

4. The method of claim 1, wherein multiplying the in-phase and quadrature components by the PN short code comprises:

multiplying the in-phase component by a first PN short code to partially despread the in-phase component; and

multiplying the quadrature component by a second PN short code to partially despread the quadrature component.

5. The method of claim 1, further comprising:

determining at least one time delay from the first and second PN short codes;

for each time delay in each phase-shifted baseband signal;

realigning an in-phase component or a quadrature component of the phase-shifted baseband signal;

multiplying the in-phase component and the quadrature component by the PN short code to partially despread components;

multiplying the partially despread in-phase and quadrature components; and

integrating the multiplied partially despread in-phase and quadrature components.

6. A method for repeating signals between multiple sources, the method comprising:

transceiving signals repeated between the multiple sources with a donor antenna and a coverage antenna;

amplifying the repeated signals between the antennas with an amplification circuit having a variable gain;

downconverting an uplink signal to a complex baseband signal;

rotating a phase of the baseband signal to a phase shift of a plurality of phase shifts;

multiplying the phase shifted baseband signal by a PN short code derived from GPS time of day; and

varying the gain based upon the multiplied baseband signal exceeding a threshold indicating the presence of a spread spectrum signal.

7. The method of claim 6, further comprising:

increasing the gain when the multiplied baseband signal exceeds the threshold indicating the presence of a spread spectrum signal.

8. The method of claim 6, further comprising:

decreasing the gain when the multiplied baseband signal does not exceed the threshold indicating the absence of a spread spectrum signal.

9. The method of claim 6, further comprising:

realigning an in-phase component or a quadrature component of the complex baseband signal;

multiplying the in-phase component by an in-phase PN short code derived from GPS time of day;

multiplying the quadrature component of the complex baseband signal by a quadrature PN short code derived from GPS time of day; and

multiplying the in-phase and quadrature components.

10. The method of claim 9, further comprising:

summing and squaring the multiplied in-phase and quadrature components over a plurality of time lags; and

comparing the summed and squared value to the threshold.

11. The method of claim 6, wherein the PN short code is generated on the fly using linear feedback shift registers.

12. The method of claim 6, wherein the PN short code is pre-computed and stored in a memory.

13. The method of claim 6, further comprising:

monitoring a reverse access channel or a reverse traffic channel to detect uplink activity at predetermined multiples.

14. A repeater for repeating signals between multiple sources, the repeater comprising:

a donor antenna and a coverage antenna for transceiving signals that are repeated between the multiple sources;

an amplification circuit positioned between the donor and coverage antennas for amplifying the repeated signals, the amplification circuit having a variable gain;

a detection circuit configured for obtaining a PN short code derived from GPS time of day for an uplink signal to the repeater and operable for downconverting the uplink signal to a complex baseband signal, rotating a phase of the baseband signal to a phase shift of a plurality of phase shifts, and multiplying the phase shifted baseband signal by the PN short code; and

the amplification circuit varying the gain based upon the multiplied baseband signal exceeding a threshold indicating the presence or absence of a spread spectrum signal.

15. The repeater of claim 14, wherein the amplification circuit increases the gain when the multiplied baseband signal exceeds the threshold indicating the presence of a spread spectrum signal.

16. The repeater of claim 14, wherein the amplification circuit decreases the gain when the multiplied baseband signal does not exceed the threshold indicating the absence of a spread spectrum signal.

17. The repeater of claim 14, wherein the detection circuit is further operable to realign an in-phase component or a quadrature component of the complex baseband signal, multiply the in-phase component by an in-phase PN short code derived from GPS time of day, multiply the quadrature component of the complex baseband signal by a quadrature PN short code derived from GPS time of day, and multiply the in-phase and quadrature components.

18. The repeater of claim 14, further comprising:

a downlink synchronization channel, wherein the GPS time of day is acquired from the downlink synchronization channel.

19. The repeater of claim 14, further comprising:

a GPS receiver module, wherein the GPS time of day is derived through the GPS receiver module.

20. The repeater of claim 14, further comprising:

a plurality of linear feedback shift registers, wherein the PN short code is generated on the fly using the shift registers.