Optical fiber-based distributed antenna systems, components, and related methods for calibration thereof

Patent metadata

Field	Value
Publication number	US-9673904-B2
Application number	US-201514822991-A
Country	US
Kind code	B2
Filing date	Aug 11, 2015
Priority date	Feb 3, 2009
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

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 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.

First claim

What is claimed is:

1. A wireless communication system, comprising:
a plurality of remote units, each configured to provide RF communications to devices located in a coverage area;
a downlink RF signal source interface configured to receive downlink electrical radio frequency (RF) signals from at least one RF signal source;
at least one optical interface module (OIM) configured to:
receive and convert the downlink electrical RF signals from the downlink RF signal source interface into downlink optical signals on at least one communication downlink; and
receive and convert uplink optical signals from at least one of the remote units into uplink electrical RF signals on at least one communication uplink;

an uplink RF signal source interface configured to receive and communicate the uplink electrical RF signals from the at least one communication uplink to the at least one RF signal source; 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;
calibrate at least one uplink gain in the at least one communication uplink, and
calibrate at least one remote unit calibration gain in the at least one remote unit by setting the at least one remote unit calibration gain in at least one attenuator in the at least one remote unit.

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

3. The wireless communication system of claim 2 , wherein the controller is configured to calibrate the downlink RF signal source calibration gain and the at least one remote unit calibration gain while electrical RF signals and optical signals are communicated over the at least one communication downlink.

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; and
the at least one calibration signal is comprised of a plurality of calibration signals each having a different frequency.

5. The wireless communication system of claim 4 , wherein the uplink gain is calibrated in the at least one communication uplink based a loss incurred in the at least one calibration signal in the at least one communication uplink.

6. The wireless communication system of claim 1 , wherein the controller is further configured to:
receive an input signal strength of the at least one calibration signal on the at least one communication downlink; and
determine a total downlink loss by comparing an end signal strength of the at least one calibration signal at the at least one remote unit with the input signal strength of the at least one calibration signal.

7. 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 RF signal source loss from the total uplink loss; and
calibrate an uplink RF signal source calibration gain in the uplink RF signal source interface based on the uplink RF signal source loss.

8. The wireless communication system of claim 7 , wherein the controller is further configured to:
calibrate at least one OIM calibration gain in the at least one OIM as the total uplink loss minus the uplink RF signal source loss; and
cause at least one uplink calibration signal to be communicated over the at least one communication uplink.

9. A wireless communication system, comprising:
a plurality of remote units, each configured to provide RF communications to devices located in a coverage area;
a downlink signal source interface configured to receive downlink electrical signals from at least one signal source;
at least one optical interface module (OIM) configured to:
receive and convert the downlink electrical signals from the downlink signal source interface into downlink optical signals on at least one communication downlink; and
receive and convert uplink optical signals from at least one of the remote units into uplink electrical signals on at least one communication uplink;

an uplink signal source interface configured to receive and communicate the uplink electrical signals from the at least one communication uplink to the at least one signal source; 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;
calibrate at least one uplink gain in the at least one communication uplink;
determine a total uplink loss for the at least one communication uplink;
determine an uplink signal source loss from the total uplink loss;
calibrate an uplink signal source calibration gain in the uplink signal source interface based on the uplink signal source loss; and
calibrate at least one OIM calibration gain in the at least one OIM as the total uplink loss minus the uplink signal source loss.

10. The wireless communication system of claim 9 , wherein the controller is further configured to:
calibrate at least one remote unit calibration gain in the at least one remote unit; and
calibrate the downlink signal source calibration gain and the at least one remote unit calibration gain while electrical signals and optical signals are communicated over the at least one communication downlink.

11. The wireless communication system of claim 9 , wherein the at least one OIM comprises a plurality of OIMs, wherein the controller is configured to calibrate a separate OIM calibration gain for each of the plurality of OIMs and cause at least one uplink calibration signal to be communicated over the at least one communication uplink.

12. The wireless communication system of claim 9 , wherein the controller is further configured to automatically calibrate the signal source calibration gain in the uplink signal source interface and the at least one OIM calibration gain in the at least one OIM.

13. A wireless communication system, comprising:
a plurality of remote units, each configured to provide RF communications to devices located in a coverage area;
a downlink RF signal source interface configured to receive downlink electrical radio frequency (RF) signals from at least one RF signal source;
at least one optical interface module (OIM) configured to:
receive and convert the downlink electrical RF signals from the downlink RF signal source interface into downlink optical signals on at least one communication downlink; and
receive and convert uplink optical signals from at least one of the remote units into uplink electrical RF signals on at least one communication uplink;

an uplink RF signal source interface configured to receive and communicate the uplink electrical RF signals from the at least one communication uplink to the at least one RF signal source; and
a controller configure

Assignees

• Corning Optical Communications LLC

Inventors

• Palanisamy Rajeshkannan
• Peters David Robert
• Sadowski Eric Michael
• Sauer Michael
• Webb Dale Alan

Classifications

• H04B10/0795

  Performance monitoring; Measurement of transmission parameters · CPC title

• H04W88/085

  Access point devices with remote components · CPC title

• H04B10/25759 Primary

  Details of the reception of RF signal or the optical conversion before the optical fibre · CPC title

• H04W24/02

  Arrangements for optimising operational condition · CPC title

• H04B10/25753

  Distribution optical network, e.g. between a base station and a plurality of remote units · CPC title