METHOD AND APPARATUS FOR UTILIZING A TRANSMISSION POLARIZATION TO REDUCE INTERFERENCE WITH A PRIMARY INCUMBENT SIGNAL

• US 20100304680A1
• Filed: 05/29/2009
• Published: 12/02/2010
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gurney, David P., Kuffner, Stephen L., Buchwald, Gregory J.
• Granted Patent: US 8,254,844 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A mobile station (104) operates in a region where an incumbent operator (110) is transmitting. The secondary station transmits at a frequency similar to that of the incumbent operator'"'"'s signal. The incumbent operator transmits using a particular polarization (113). To reduce interference, the secondary station selects one of a plurality of antennas of the secondary station which has a low matching polarization with that of the incumbent signal.

Claims

1. A method of transmitting a signal in a secondary communications system comprising:

estimating a received signal polarization of at least one protected signal,

estimating an interference contribution to the at least one protected signal, by a secondary station transmission of a secondary station of the secondary communication system;

determining a transmission configuration at the secondary station that meets an interference contribution criteria; and

transmitting from the secondary station using the determined transmission configuration.

2. The method of claim 1, wherein the transmission configuration comprises at least one of a transmission polarization configuration or a transmission power level.

3. The method of claim 1 wherein the interference contribution criteria comprises a maximum permissible interference effect on the protected signal at a particular location.

4. The method of claim 1, wherein the interference contribution criteria is selected to minimize the interference contribution to the protected signal.

5. The method of claim 1 wherein estimating the received signal polarization comprises accessing a geo-location database.

6. The method of claim 1 wherein estimating the received signal polarization comprises sensing on a plurality of antenna polarizations of the secondary station.

7. The method of claim 2, wherein the transmission polarization configuration is selected based on an orientation sensor of the secondary station indicating an orientation of the secondary station.

8. The method of claim 2 wherein the transmission polarization configuration is selected among a plurality of antennas having different antenna polarizations.

9. The method of claim 2 wherein the transmission polarization configuration comprises a combination of a plurality of antenna polarizations of the secondary station.

10. The method of claim 6, wherein the sensing comprises estimating an amplitude and phase of the protected signal for at least one of the antenna polarizations.

11. A method of transmitting a signal in a secondary transmitter comprising:

sensing an ambient radio environment on a candidate channel using a plurality of antennas of the mobile station, each of the plurality of antennas having a unique polarization;

selecting one antenna of the plurality of antennas by;

when an incumbent signal is detected on the candidate channel, selecting an antenna from the plurality of antennas having a lowest matching polarization with the incumbent signal for subsequent transmission by the mobile station; and

when no incumbent signal is detected on the candidate channel, selecting an antenna from the plurality of antennas that has a highest matching polarization with a receiving station to which the mobile station is transmitting.

12. The method of claim 11, wherein the sensing and selecting are repeated periodically.

13. The method of claim 11, wherein the incumbent signal is detected adjacent to the candidate channel.

14. The method of claim 11, wherein the incumbent signal is detected in the candidate channel.

15. The method of claim 11, wherein the plurality of antennas comprises first and second antennas having orthogonal polarization with respect to each other.

16. A method of operating a secondary station, comprising:

determining, at the secondary station, a polarization of an incumbent signal on a candidate channel; and

configuring a transmitter of the secondary station such that at least a majority of transmit power is routed to one of a plurality of antennas having a lowest matching polarization relative to the polarization of the incumbent signal.

17. The method of claim 16, wherein determining the polarization of the incumbent signal comprises querying a geo-location database of incumbent signals and receiving signal parameters of the incumbent signal from the geo-location database, and wherein the signal parameters comprise a polarization indication parameter.

18. The method of claim 17 wherein configuring the transmitter comprises selecting only the antenna having the lowest matching polarity.

19. The method of claim 17, wherein determining the polarization comprises receiving the incumbent signal at each of the plurality of antennas, wherein the antenna having the lowest received signal strength is selected as the antenna having the lowest matching polarization.

20. The method of claim 17, wherein the mobile station comprises an orientation sensor, configuring the transmitter comprises:

determining an orientation of the mobile station as indicated by the orientation sensor; and

selecting one of the plurality of antennas having a polarization most opposite of the polarization of the incumbent signal.

21. The method of claim 17, wherein determining the polarization and configuring the transmitter are repeated.

22. A cognitive secondary station, comprising:

a transceiver;

a plurality of antennas, each of the plurality of antenna able to be selectively coupled to the transceiver, and having a unique polarization relative to the mobile station; and

a controller configured to operate the transceiver and selectively couple at least one of the plurality of antennas to the transceiver in response to the mobile station determining a polarization of an incumbent signal on a channel which the transceiver is configured to operate, and wherein the at least one of the plurality of antennas has a lowest matching polarization with the incumbent signal.