Distributed antenna system for MIMO signals

• US 8,396,368 B2
• Filed: 12/09/2009
• Issued: 03/12/2013
• Est. Priority Date: 12/09/2009
• Status: Active Grant

• Current Assignee: Andrew Wireless Systems GmbH (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Tarlazzi, Luigi, Brighenti, Samuele, Faccin, Pier
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US12/634,212
• Publication Number:
  US 20110135308A1
• Time in Patent Office: 1,189 Days
• Field of Search: 398115-118
• US Class Current: 398/115
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0682 using phase diversity (e.g. phase sweeping)
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/0252 Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/028 WDM bus architectures
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A distributed antenna system (DAS) includes a multiple-input and multiple-output (“MIMO”) base station configured to output at least a first and second signal, and a hybrid coupler coupled thereto, the coupler configured to receive the first and second signal from the MIMO base station on respective first and second ports and provide an output signal on at least one output port, the output signal including at least a portion of the first signal and at least a portion of the second signal. The DAS further includes a master unit communicating with the coupler and configured to receive at least the output signal, and at least one remote unit communicating with the master unit and configured to communicate the output signal to a device.

Claims

1. A system comprising:

a multiple-input and multiple-output (MIMO) base station configured to output a first branch of a MIMO signal and a second branch of the MIMO signal, the branches of the MIMO signal being in the same frequency channel and one of the branches including signaling parameters;

a hybrid coupler coupled to the MIMO base station, the coupler configured to receive the first branch of the MIMO signal and the second branch of the MIMO signal from the MIMO base station on respective first and second input ports and provide output signals on first and second output ports, the output signal on the first output port including at least a portion of the first branch of the MIMO signal and at least a portion of the second branch of the MIMO signal that is phase shifted orthogonally in relation to the respective second branch of the MIMO signal and the output signal on the second output port including at least a portion of the second branch of the MIMO signal and at least a portion of the first branch of the MIMO signal that is phase shifted orthogonally in relation to the respective first branch of the MIMO signal;

at least one master unit communicating with the coupler and configured to receive the output signal from the first output port of the coupler for distributing the output signal to one or more remote units;

at least another master unit communicating with the coupler and configured to receive the output signal from the second output port of the coupler for distributing the output signal to one or more remote units;

a plurality of remote units communicating with the at least one master unit and a plurality of remote units communicating with the at least another master unit to communicate both the output-signal of the first output port and the output signal of the second output port to a device for providing MIMO communications.

2. The system of claim 1, wherein the remote units communicate with the master units over optical links.

3. The system of claim 2, wherein at least one of the optical links comprises:

a first optical fiber for carrying uplink signals; and

a second optical fiber for carrying downlink signals,

wherein the first and second optical fibers are configured as half duplex channels.

4. The system of claim 2, wherein at least one of the optical links comprises:

an optical fiber for carrying uplink and downlink signals on different wavelengths; and

a wavelength division multiplexer configured to combine or split the uplink and downlink signals on the optical fiber.

5. The system of claim 1, wherein at least one of the remote units communicates with at least one of the master units over a high data rate media selected from a group consisting of coaxial cable, twisted pair copper wires, a free space radio frequency link, and a shared network, and combinations thereof.

6. The system of claim 5, wherein the shared network is selected from a group consisting of Ethernet, SONET, SDH, ATM, PDH, and combinations thereof.

7. The system of claim 2, wherein the optical links carry at least one of a modulated digital signal or a radio-over-fiber (RoF) signal.

8. The system of claim 1, wherein the coupler is a 90°

3 dB hybrid coupler.

9. The system of claim 1 further comprising a SISO base station, the SISO base station being selectively coupled with at least one of the master units and providing a SISO output signal.

10. The system of claim 9, wherein the at least one master unit is further configured to communicate the output signal from the SISO base station simultaneously with the output signals of the MIMO base station.

11. The system of claim 9, wherein the system may be selectively operated in a SISO mode of operation or a MIMO mode of operation, wherein, in the SISO mode of operation, the at least one master unit and a respective plurality of remote units handle SISO output signals and in the MIMO mode of operation the at least one master unit and a respective plurality of remote units handle MIMO output signals.

12. The system of claim 1, wherein at least one of the plurality of remote units is configured to communicate the respective output signal to a device with an air interface that includes at least one of an antenna and a radiating cable.

13. A method for transmitting signals through a distributed system comprising:

providing at least a first branch of a MIMO signal and a second branch of the MIMO signal, the branches of the MIMO signal being in the same frequency channel and one of the branches including signaling parameters;

delivering the first and second branches of the MIMO signal to respective first and second input ports of a hybrid coupler;

providing output signals on first and second output ports of the coupler, the output signal on the first output port including at least a portion of the first branch of the MIMO signal and at least a portion of the second branch of the MIMO signal that is phase shifted orthogonally in relation to the respective second branch of the MIMO signal and the output signal on the second output port including at least a portion of the second branch of the MIMO signal and at least a portion of the first branch of the MIMO signal that is phase shifted orthogonally in relation to the respective first branch of the MIMO signal;

directing the output signal from the first output port to at least one master unit communicating with the coupler for distributing the output signal to one or more remote units;

directing the output signal from the second output port to at least another master unit communicating with the coupler for distributing the output signal to one or more remote units;

forwarding the output signal from the at least one master unit to a plurality of remote units communicating with the at least one master unit and forwarding the output signal from the at least another master unit to a plurality of remote units and communicating both the output signal of the first output port and the output signal of the second output port to a device from the remote units for providing MIMO communications.

14. The method of claim 13 wherein the remote units communicate with the master units over optical links.

15. The method of claim 13 wherein at least one of the remote units communicates with at least one of the master units over a high data rate media selected from a group consisting of coaxial cable, twisted pair copper wires, a free space radio frequency link, and a shared network, and combinations thereof.

17. The system of claim 15, wherein the at least one remote unit communicates with the at least one master unit over an optical link.

18. The system of claim 17, wherein the optical link comprises at least one of first and second optical fibers for carrying respective uplink and downlink signals or a an optical fiber for carrying both uplink and downlink signals on different wavelengths.

20. The system of claim 17, wherein the optical link carries at least one of a modulated digital signal or a radio-over-fiber (RoF) signal.

16. A system comprising:

a multiple-input and multiple-output (MIMO) base station configured to output a first branch of a MIMO signal and a second branch of the MIMO signal;

a hybrid coupler coupled to the MIMO base station, the coupler configured to receive the first branch of the MIMO signal and the second branch of the MIMO signal from the MIMO base station on respective first and second input ports and provide a first output signal on an output port, the first output signal including a portion of the first branch of the MIMO signal and a portion of the second branch of the MIMO signal;

a single-input and single-output (SISO) base station configured to output a SISO output signal as a second output signal;

a summing circuit communicating with the output port of the coupler and the SISO base station, the summing circuit configured to combine the first and second output signals and provide a combined output signal;

at least one master unit communicating with the summing circuit and configured to receive the combined output signal; and

at least one remote unit communicating with the at least one master unit and configured to provide the combined output signal to a coverage area.

19. The system of claim 16, wherein the at least one remote unit communicates with the at least one master unit over a high data rate media selected from a group consisting of coaxial cable, twisted pair copper wires, a free space radio frequency link, and a shared network and combinations thereof.

21. The system of claim 16, wherein the hybrid coupler is a 90°

3 dB hybrid coupler.

22. The system of claim 16, wherein the hybrid coupler includes a second output port having another output signal that includes a portion of the second branch of the MIMO signal and a portion of the first branch of the MIMO signal, the system further including:

at least another master unit communicating with the coupler and configured to receive the another output signal from the second output port of the coupler for distributing the output signal to one or more remote units; and

at least another remote unit communicating with the at least another master unit and configured to communicate at least another signal to the coverage area.