Interference cancellation system and method for wireless antenna configuration

• US 7,715,466 B1
• Filed: 01/13/2005
• Issued: 05/11/2010
• Est. Priority Date: 02/27/2002
• Status: Expired due to Term

• Current Assignee: Sprint Spectrum LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Yarkosky, Mark, Steele, Thomas M., Oh, Dae-Sik, Hayne, Kristin A.
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): HUANG, DAVID S
• Application Number:
  US11/035,140
• Time in Patent Office: 1,944 Days
• Field of Search: 375/259, 375/260, 375/264, 375/265, 375/295, 375/296, 375/316, 375/211, 455/3.01, 455/3.03, 455/456.1, 455/456.5, 455/456.6, 455/7, 455 15- 16, 370/310, 370/315, 370/320, 370/321, 370/332, 370/334
• US Class Current: 375/211
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

Presently disclosed is a method for reducing interference in a wireless distributed antenna systems. In an embodiment, interference is reduced by selectively placing a first wireless remote unit in a reduced signal interference mode. A controller sends a signal, such as a reverse link power-down signal, to the first remote unit after detecting less than a threshold incoming signal strength at the first remote unit. In an alternative embodiment, the controller requests that a given remote unit switch to the reduced signal interference mode when the controller is receiving signals from a mobile station through at least two different remote units.

Claims

1. A method comprising:

providing a communication link between a mobile station and a controller in a wireless distributed antenna system (WDAS), wherein the WDAS is implemented inside a building and wherein the controller is a wireless distributed antenna system controller (WDASC);

receiving an indication at the controller that the mobile station is communicating through at least two remote units of the WDAS by receiving a radio-frequency message from each of the at least two remote units, wherein the mobile station is within the building;

selecting a first remote unit from the at least two remote units;

wirelessly transmitting a signal from the controller to the first remote unit, wherein the signal includes an indication to switch a radio-frequency (RF) reverse-link from the first remote unit to the controller to a reduced signal interference mode;

wherein selecting the first remote unit comprises;

comparing signal strengths received by the at least two remote units; and

based on the comparison, selecting the first remote unit, wherein the signal strength received by the first remote unit is less than the signal strength received by at least one of the remote units.

2. The method of claim 1, further comprising:

switching the first remote unit to the reduced signal interference mode.

3. The method of claim 1, wherein switching the RF reverse-link to a reduced signal interference mode comprises switching off the RF reverse-link.

4. The method of claim 1, further comprising:

selecting a second remote unit for continuing communication with the mobile station, wherein the second remote unit is different from the first remote unit.

5. The method of claim 1, wherein the WDASC is configured to communicate with a plurality of remote units over a CDMA radio-frequency (RF) network.

6. The method of claim 1, further comprising:

determining that no mobile station is operating in a coverage area of the first remote unit; and

responsively wirelessly transmitting a signal from the controller to the first remote unit indicating to switch the first remote unit to a reduced signal interference mode.

7. The method of claim 1, further comprising:

the first remote unit receiving an origination signal from a second mobile station; and

the first remote unit switching to a normal mode.

8. The method of claim 1, further comprising:

selecting a second remote unit for continuing communication with the mobile station, wherein the second remote unit is different from the first remote unit; and

after termination of a connection between the mobile station and the second remote unit, wirelessly transmitting a signal from the controller to the first remote unit indicating to switch the first remote unit to a normal mode.

9. In a wireless distributed antenna system (WDAS) implemented within a building having a WDAS controller (WDASC) and a plurality of WDAS remote units distributed throughout a geographic coverage area for providing a wireless communications platform for a mobile station (MS), a method of reducing signal interference comprising:

at the WDASC, detecting a plurality of signals from the MS, the signals having arrived from at least two of the plurality of WDAS remote units, wherein each of the plurality of the WDAS remote units comprises a variable gain amplifier, a user interface accessible via the Internet, and a rules engine, wherein the WDASC identifies each of the plurality of the WADS remote units based on a pseudo-random sequence (PN) of a decoded signal sent from each WDAS remote unit;

at the WDASC, selecting a first remote unit from the at least two WDAS remote units;

from the WDASC, wireless transmitting a first message to the first remote unit for shutting off a back-end reverse-link of the first remote unit;

wherein the selection of the first remote units is based at least in part on a measure of incoming signal strength from the MS at the first remote unit.

10. The method of claim 9, further comprising:

at the first remote unit, shutting off the back-end reverse-link of the first remote unit.

11. The method of claim 10, further comprising:

after shutting off the back-end reverse link of the first remote unit, receiving a second message at the first remote unit; and

in response to the second message, switching on the back-end reverse-link of the first remote unit.

12. The method of claim 11, wherein the second message is transmitted from the WDAS controller.

13. The method of claim 11, wherein the second message is transmitted from a second MS.