Smart antenna array over fiber

• US 20080007453A1
• Filed: 06/07/2007
• Published: 01/10/2008
• Est. Priority Date: 06/12/2006
• Status: Abandoned Application

• Current Assignee: Powerwave Technologies Incorporated
• Original Assignee: Powerwave Technologies Incorporated
• Inventors: Hunton, Matthew J., Rabinovich, Alexander, Vassilakis, Bill
• Application Number:
  US11/810,840
• Publication Number:
  US 20080007453A1
• Time in Patent Office: Days
• US Class Current: 342/368
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/0025 Modular arrays
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H01Q 3/2676 Optically controlled phased array

Abstract

A smart antenna system includes a plurality of antennas, a plurality of Transmit—Receive Modules (TRMs) coupled respectively to the plurality of antennas, and a beam steering module coupled to the plurality of TRMs and providing radiation beam steering for the plurality of TRMs. The beam steering module includes a pilot generator for generating a pilot signal and providing it to the TRMs to calibrate a receive (RX) reference plane. The pilot signal is injected at a first location before the receiver section into the RX path, and the pilot signal is sampled at a second location after the receiver section. The TRMs and the beam steering module can also be used to calibrate a transmit (TX) reference plane by sampling output signals from the TRMs. The output signals have a pilot signal component, and are sampled at the first location in the TX path after the transmitter section.

Claims

1. A smart antenna system, comprising:

a plurality of antennas;

a plurality of Transmit—

Receive Modules (TRMs) coupled respectively to the plurality of antennas; and

a beam steering module coupled to the plurality of TRMs and providing radiation beam steering for the plurality of TRMs, wherein the beam steering module comprises a pilot generator for generating a pilot signal and providing it to the TRMs to calibrate a receive (RX) reference plane.

2. A smart antenna system as set out in claim 1, wherein the pilot signal is a CDMA signal with a unique pilot code.

3. A smart antenna system as set out in claim 1, wherein each TRM comprises:

a first signal sampling coupler for injecting the pilot signal into an RX path in the TRM; and

a second signal sampling coupler for sampling a feedback pilot signal and providing it to the beam steering module.

4. A smart antenna system as set out in claim 3, wherein each TRM further comprises a demodulator, and wherein the second signal sampling coupler is located before the demodulator in the RX path.

5. A smart antenna system as set out in claim 3, wherein each TRM further comprises a demodulator, and wherein the second signal sampling coupler comprises a demodulated-data diverter connected to an output of the demodulator in the RX path.

6. A smart antenna system as set out in claim 3, wherein each TRM further comprises:

a duplexer;

a receiver section; and

an I/Q modulator in the RX path between the first signal sampling coupler and the second signal sampling coupler,

wherein the feedback pilot signal carries one or more of phase, amplitude, and delay information of the RX path.

7. A smart antenna system as set out in claim 6, wherein the beam steering module further comprises:

a master controller for calibrating the RX reference plane;

an in-phase aggregator for summing a plurality of feedback pilot signals from the plurality of TRMs; and

a received signal strength indication (RSSI) processor for receiving the summed feedback pilot signal from the in-phase aggregator and for outputting a signal indicative of a difference among the plurality of feedback pilot signals to the master controller.

8. A smart antenna system as set out in claim 7, wherein the master controller is configured to adjust a phase of the I/Q modulator for calibrating the RX reference plane.

9. A smart antenna system as set out in claim 1, wherein the beam steering module further comprises:

a signal circulator for isolating the generated pilot signal and directing the pilot signal; and

a signal divider/combining network dividing the generated pilot signal and sending the divided pilot signals to the plurality of TRMs.

10. A smart antenna system as set out in claim 9, wherein the signal divider/combining network is adapted to divide the generated pilot signal into N pilot signals, and to send each of the N divided pilot signals to a corresponding TRM among a total number of N TRMs.

11. A smart antenna system as set out in claim 1, wherein the beam steering module comprises a fiber optic backplane (FOB), and wherein the FOB is coupled to a base station via a fiber optic interface.

12. A smart antenna system, comprising:

a plurality of antennas;

a plurality of Transmit—

Receive Modules (TRMs) coupled respectively to the plurality of antennas; and

a beam steering module coupled to the plurality of TRMs and providing radiation beam steering for the plurality of TRMs,

wherein each TRM comprises;

a data port;

a modulator adapted for receiving a CDMA signal having a pilot from a base station and providing a modulated RF signal; and

an amplifier,

wherein the amplifier is configured to amplify the CDMA signal before outputting the amplified CDMA signal to a corresponding antenna,

wherein the beam steering module is configured for receiving sampled output signals from the plurality of TRMs and for calibrating a transmit (TX) reference plane based on a detected pilot signal therein.

13. A smart antenna system as set out in claim 12, wherein each TRM further comprises a signal coupler for sampling the output signal and providing the sampled output signal to the beam steering module.

14. A smart antenna system as set out in claim 13, wherein the signal coupler is also adapted to inject a pilot signal generated within the beam steering module into the TRM to calibrate a receive (RX) reference plane.

15. A smart antenna system as set out in claim 13, wherein the sampled output signal carries one or more of phase, amplitude, and delay information of a TX path.

16. A smart antenna system as set out in claim 13, wherein the beam steering module further comprises:

a rake receiver for receiving a combined signal from the signal divider/combining network; and

a master controller for calibrating the TX reference plane based on an output of the rake receiver.

17. A smart antenna system as set out in claim 16, wherein the beam steering module further comprises means for cross correlating the plurality of sampled output signals from the plurality of TRMs.

18. A smart antenna system as set out in claim 16, further comprising:

a signal divider/combining network for combining a plurality of sampled output signals from the plurality of TRMs,

wherein the signal divider/combining network is also part of a receive (RX) reference plane calibration signal path.

19. A smart antenna system as set out in claim 18, wherein the master controller is also adapted to calibrate the RX reference plane.

20. A smart antenna system as set out in claim 12, wherein each TRM further comprises means for selecting prescribed pseudo noise (PN) spreading codes.

21. A smart antenna system as set out in claim 12, wherein the beam steering module comprises a fiber optic backplane (FOB), and wherein the FOB is coupled to a base station via a fiber optic interface.

22. A method for calibrating a smart antenna system having a plurality of antennas each coupled to a receive (RX) path including a receiver section, the method comprising:

injecting a pilot signal at a first location before the receiver section into the RX path;

sampling the pilot signal at a second location after the receiver section; and

calibrating an RX reference plane based on the sampled pilot signal.

23. A method as set out in claim 22, wherein calibrating the RX reference plane further comprises:

applying a pilot cancellation technique on the sampled pilot signal.

24. A method as set out in claim 23, wherein applying the pilot cancellation technique on the pilot signal comprises:

adjusting a phase of the pilot signal.

25. A method as set out in claim 22, further comprising:

calibrating a transmit (TX) reference plane.

26. A method as set out in claim 25, wherein:

calibrating the TX reference plane comprises sampling a transmit signal in a TX path at the first location.

27. A method as set out in claim 26, wherein:

sampling the transmit signal comprises sampling existing transmit signal to be sent to a user terminal equipment (UTE).

28. A method as set out in claim 26, wherein:

calibrating the TX reference plane further comprises summing a plurality of sampled transmit signals corresponding to the plurality of antennas using a signal divider/combining network.

29. A method as set out in claim 28, wherein calibrating the RX reference plane comprises dividing the pilot signal using the same signal divider/combining network.

30. A method as set out in claim 28, wherein calibrating the TX reference plane further comprises:

selecting prescribed pseudo noise (PN) spreading codes for the transmit signal to be sampled; and

cross correlating the plurality of sampled transmit signals.

31. A method as set out in claim 26, wherein calibrating the TX reference plane further comprises adjusting a phase of the transmit signal using a master controller.

32. A method as set out in claim 31, wherein calibrating the RX reference plane comprises adjusting a phase of the pilot signal using the same master controller.

33. A method for calibrating a smart antenna system having a plurality of antennas each coupled to a transmit (TX) path including a transmitter section, the method comprising:

sampling a transmit signal having a pilot signal component from each of the TX paths at a first location in the TX path after the transmitter section; and

calibrating a TX reference plane based on the sampled transmit signal.

34. A method as set out in claim 33, wherein calibrating the TX reference plane further comprises:

selecting prescribed pseudo noise (PN) spreading codes for the transmit signal to be sampled; and

cross correlating the plurality of sampled transmit signals to extract the pilot signal.

35. A method as set out in claim 33, further comprising:

calibrating an RX reference plane by injecting a test signal to an RX path at the first location.

36. A method as set out in claim 35, further comprising:

summing a plurality of the sampled transmit signals using a divider/combining network; and

dividing the test signal into a plurality of test signals using the divider/combining network.

37. A method as set out in claim 35, further comprising:

adjusting a phase of the test signal using a master controller; and

adjusting a phase of the transmit signal using the master controller.

38. A communication system, comprising:

a base station;

a fiber optic communication link; and

a smart antenna system coupled to the base station via the fiber optic communication link, the smart antenna system comprising;

a plurality of Transmit—

Receive Modules (TRMs); and

a fiber optic backplane (FOB) coupled to fiber optic communication link and to the plurality of TRMs through a second interface and providing radiation beam steering for the plurality of TRMs,

wherein the FOB comprises a pilot generator for generating a test signal to calibrate a receive (RX) reference plane,

wherein a transmit signal in each of the plurality of TRMs is sampled for calibrating a transmit (TX) reference plane.

39. A communication system as set out in claim 38, wherein each TRM comprises a coupler at a first location in an RX path for injecting the test signal from the FOB into the RX path in the TRM, and wherein the coupler is also adapted for sampling the transmit signal from a TX path in the TRM into the FOB.

40. A communication system as set out in claim 39, wherein the FOB further comprises a master controller for calibrating both the RX reference plane and the TX reference plane.

41. A communication system as set out in claim 39, wherein the FOB further comprises a signal divider/combining network for combining a plurality of transmit signals from the plurality of TRMs sampled into the FOB from the coupler, and for dividing the test signal and sending the divided test signal to the plurality of TRMs through the coupler.