OPTICAL FIBER-BASED DISTRIBUTED ANTENNA SYSTEMS, COMPONENTS, AND RELATED METHODS FOR CALIBRATION THEREOF

• US 20130272696A1
• Filed: 06/12/2013
• Published: 10/17/2013
• Est. Priority Date: 02/03/2009
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Cable Systems LLC (Corning Incorporated)
• Inventors: Palanisamy, Rajeshkannan, Sauer, Michael, Webb, Dale Alan, Peters, David Robert, Sadowski, Eric Michael
• Granted Patent: US 9,112,611 B2
• Time in Patent Office: Days
• US Class Current: 398/25
• CPC Class Codes: H04B 10/25754 Star network topology
• CPC Class Codes: H04B 10/25758 between a central unit and a single remote unit by means of an optical fibre
• CPC Class Codes: H04B 10/271 Combination of different networks, e.g. star and ring configuration in the same network or two ring networks interconnected
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

Optical fiber-based wireless systems and related components and methods are disclosed. The systems support radio frequency (RF) communications with clients over optical fiber, including Radio-over-Fiber (RoF) communications. The systems may be provided as part of an indoor distributed antenna system (IDAS) to provide wireless communication services to clients inside a building or other facility. The communications can be distributed between a head end unit (HEU) that receives carrier signals from one or more service or carrier providers and converts the signals to RoF signals for distribution over optical fibers to end points, which may be remote antenna units (RAUs). In one embodiment, calibration of communication downlinks and communication uplinks is performed to compensate for signal strength losses in the system.

Claims

1. A wireless communication system, comprising:

a downlink base transceiver station (BTS) interface configured to receive downlink electrical radio frequency (RF) signals from at least one BTS;

at least one optical interface module (OIM) configured to;

receive and convert the downlink electrical RF signals from the downlink BTS interface into downlink Radio-over-Fiber (RoF) signals on at least one communication downlink; and

receive and convert uplink RoF signals from at least one remote antenna unit (RAU) into uplink electrical RF signals on at least one communication uplink;

an uplink BTS interface configured to receive and communicate the uplink electrical RF signals from the at least one communication uplink to the at least one BTS; and

a controller configured to;

inject at least one calibration signal over the at least one communication downlink;

calibrate at least one downlink gain in the at least one communication downlink based on a loss incurred in the at least one calibration signal in the at least one communication downlink;

cause the at least one calibration signal to be switched from the at least one communication downlink to the at least one communication uplink; and

calibrate at least one uplink gain in the at least one communication uplink based on a loss incurred in the at least one calibration signal in the at least one communication uplink.

2. The wireless communication system of claim 1, wherein the controller is configured to calibrate a downlink BTS calibration gain in the downlink BTS interface by setting the downlink BTS calibration gain in at least one attenuator in the downlink BTS interface.

3. The wireless communication system of claim 1, wherein the controller is configured to calibrate at least one RAU calibration gain in the at least one RAU by setting the at least one RAU calibration gain in at least one attenuator in the at least one RAU.

4. The wireless communication system of claim 1, wherein a frequency of the at least one calibration signal is different from a frequency of the downlink electrical RF signals.

5. The wireless communication system of claim 1, wherein the controller is configured to receive an input signal strength of the at least one calibration signal on the at least one communication downlink.

6. The wireless communication system of claim 5, wherein the controller is configured to determine a total downlink loss by comparing an end signal strength of the at least one calibration signal at the at least one RAU with the input signal strength of the at least one calibration signal.

7. The wireless communication system of claim 1, wherein the at least one calibration signal is comprised of a plurality of calibration signals each having a different frequency.

8. The wireless communication system of claim 3, wherein the controller is configured to calibrate the downlink BTS calibration gain and the at least one RAU calibration gain while electrical RF signals and RoF signals are communicated over the at least one communication downlink.

9. The wireless communication system of claim 3, wherein the controller is configured to automatically calibrate the downlink BTS calibration gain in the downlink BTS interface and the at least one RAU calibration gain in the at least one RAU.

10. The wireless communication system of claim 1, wherein the controller is further configured to:

determine a total uplink loss for the at least one communication uplink;

determine an uplink BTS loss from the total uplink loss;

calibrate an uplink BTS calibration gain in the uplink BTS interface based on the uplink BTS loss; and

calibrate at least one OIM calibration gain in the at least one OIM as the total uplink loss minus the uplink BTS loss.

11. The wireless communication system of claim 10, wherein the at least one OIM is comprised of a plurality of OIMs, and wherein the controller is configured to calibrate a separate OIM calibration gain for each of the plurality of OIMs.

12. The wireless communication system of claim 11, wherein the controller is further configured to cause at least one uplink calibration signal to be communicated over the at least one communication uplink.

13. The wireless communication system of claim 12, wherein a frequency of the at least one uplink calibration signal is different from a frequency of the uplink electrical RF signals.

14. The wireless communication system of claim 12, wherein the controller is configured to receive an input signal strength of the at least one uplink calibration signal on the at least one communication uplink.

15. The wireless communication system of claim 14, wherein the controller is configured to determine the total uplink loss by comparing an end signal strength of the at least one uplink calibration signal at the uplink BTS interface with the input signal strength of the at least one uplink calibration signal at the at least one RAU.

16. The wireless communication system of claim 10, wherein the controller is configured to calibrate the uplink BTS calibration gain in the uplink BTS interface and the at least one OIM calibration gain in the at least one OIM while electrical RF signals and RoF signals are communicated over the at least one communication uplink.

17. The wireless communication system of claim 10, wherein the controller is configured to automatically calibrate the BTS calibration gain in the uplink BTS interface and the at least one OIM calibration gain in the at least one OIM.

18. A wireless communication system, comprising:

a downlink base transceiver station (BTS) interface configured to receive downlink electrical radio frequency (RF) signals from at least one BTS;

at least twelve (12) optical interface modules (OIM) each configured to;

receive and convert the downlink electrical RF signals from the downlink BTS interface into downlink Radio-over-Fiber (RoF) signals on at least one of at least thirty-six (36) communication downlinks; and

receive and convert uplink RoF signals from at least three (3) remote antenna units (RAUs) into uplink electrical RF signals on at least one of at least thirty-six (36) communication uplinks;

an uplink BTS interface configured to receive and communicate the uplink electrical RF signals from the at least thirty-six (36) communication uplinks to the at least one BTS; and

a controller configured to calibrate at least one downlink gain for each of the thirty-six (36) communication downlinks.

19. The wireless communication system of claim 18, wherein the controller is further configured to cause first and second downlink calibration signals to be communicated over each of the thirty-six (36) communication downlinks.

20. The wireless communication system of claim 18, wherein the controller is further configured to:

determine a total uplink loss for the at least thirty-six (36) communication uplinks;

determine an uplink BTS loss from the total uplink loss;

calibrate a BTS calibration gain in the uplink BTS interface based on the uplink BTS loss; and

calibrate at least one OIM calibration gain in one of the at least twelve (12) OIMs as the total uplink loss minus the uplink BTS loss.

21. A wireless communication system, comprising:

a downlink base transceiver station (BTS) interface configured to receive downlink radio frequency (RF) signals from at least one BTS;

at least one optical interface module (OIM) configured to;

receive the downlink RF signals from the downlink BTS interface for transmission as Radio-over-Fiber (RoF) signals on at least one communication downlink; and

receive uplink RoF signals from at least one remote antenna unit (RAU) for transmission as uplink RF signals on at least one communication uplink;

an uplink BTS interface configured to receive and communicate the uplink RF signals from the at least one communication uplink to the at least one BTS; and

a controller configured to;

inject at least one calibration signal over the at least one communication downlink;

calibrate at least one downlink gain in the at least one communication downlink based on a loss incurred in the at least one calibration signal in the at least one communication downlink;

cause the at least one calibration signal to be switched from the at least one communication downlink to the at least one communication uplink; and

calibrate at least one uplink gain in the at least one communication uplink based on a loss incurred in the at least one calibration signal in the at least one communication uplink.

22. The wireless communication system of claim 21, wherein the controller is further configured to:

calibrate a downlink BTS calibration gain in the downlink BTS interface by setting the downlink BTS calibration gain in at least one attenuator in the downlink BTS interface; and

calibrate at least one RAU calibration gain in the at least one RAU by setting the at least one RAU calibration gain in at least one attenuator in the at least one RAU.

23. The wireless communication system of claim 21, wherein the controller is further configured to:

determine a total uplink loss for the at least one communication uplink;

determine an uplink BTS loss from the total uplink loss; and

calibrate an uplink BTS calibration gain in the uplink BTS interface based on the uplink BTS loss.