Methods and apparatus for antenna isolation-dependent coexistence in wireless systems

• US 8,688,056 B2
• Filed: 10/08/2012
• Issued: 04/01/2014
• Est. Priority Date: 06/26/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Chen, Camille, Robinson, Michael A., Giles, Michael J.
• Primary Examiner(s): Nooristany, Sulaiman
• Application Number:
  US13/647,307
• Publication Number:
  US 20130035047A1
• Time in Patent Office: 540 Days
• Field of Search: 455/79
• US Class Current: 455/79
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 52/0238 where the received signal is an unwanted signal, e.g. interference or idle signal
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatus for selectively switching one or more antennas in a multiple-input, multiple-output (MIMO) antenna array so as to mitigate interference with another RF interface within the same space-constrained device, based on radio frequency isolation. In one embodiment, the MIMO interface comprises a WLAN interface having a 2×2 or 3×3 array of antennae which are placed in a wireless device in an asymmetric fashion with respect to the antenna of the second interface, and the other interface comprises a PAN (e.g., Bluetooth) interface operating in an overlapping frequency band (e.g., ISM band). When both interfaces are operating, interference is mitigated through selectively switching off one or more of the MIMO antennae, and using the remaining antenna(e) having the best isolation from the Bluetooth antennae. This approach allows simultaneous operation of both interferences without significant degradation to user experience or the operation of either interface, and may also provide power savings critical to mobile device battery longevity.

Claims

1. A method of operating a multi-input multi-output (MIMO)-capable air interface of a device having at least one other air interface, the method comprising:

communicating, from said one other air interface to said MIMO-capable interface, a communication activity level of said one other air interface;

when said MIMO-capable interface and said one other air interface are operating simultaneously, then determining a radio frequency isolation between at least two antenna elements of said MIMO-capable interface and said one other air interface, wherein said determining comprises determining a time-variant isolation;

classifying said radio frequency isolation as one of symmetric or asymmetric; and

based at least in part on said communicated communication activity level and said determined radio frequency isolation, configuring said MIMO-capable interface to operate a first number of said antenna elements.

2. The method of claim 1, wherein said determining comprises determining a static isolation.

3. The method of claim 2, wherein said determining is based on a physical layout of antennae of said device.

4. The method of claim 1, wherein said determining is based at least in part on an attenuator setting.

5. The method of claim 4, wherein said attenuator setting is obtained from front end radio circuitry of at least one of said MIMO-capable interface and said one other interface.

6. The method of claim 1, wherein said communicating comprises communicating using a hardware-based signal.

7. The method of claim 1, wherein said communicating comprises communicating using a software message.

8. The method of claim 1, wherein when said radio frequency isolation is classified as asymmetric, then said first number of antenna elements is 1.

9. A non-transitory computer readable apparatus having a storage medium, said storage medium configured to store a computer program comprising instructions which, when executed cause a processor to:

determine whether a time variant isolation condition is symmetric or asymmetric by comparing one or more isolations between antennae of a plurality of antenna pairs associated with a first and a second air interfaces;

when the time variant isolation condition is asymmetric, identify at least one antenna within said first interface characterized by low isolation, said first interface comprising a multi-input, multi-output (MIMO) air interface; and

turn off the identified at least one antenna.

10. A wireless device, comprising:

a multi-input multi-output (MIMO)-capable air interface;

at least one other air interface;

a processor; and

a non-transitory computer readable apparatus having a storage medium and in data communication with the processor, the storage medium configured to store a computer program comprising instructions which, when executed cause the wireless device to;

communicate from the one other air interface to the MIMO-capable interface a communication activity level relating to the one other air interface;

responsive to the communication, determine a time variant radio frequency isolation between the at least two antenna elements of the MIMO-capable interface and the one other air interface;

classify the time variant radio frequency isolation as one of symmetric or asymmetric; and

based at least in part on the communicated communication activity level and the determined time variant radio frequency isolation, configure the MIMO-capable interface to operate a first number of the antenna elements.

11. The wireless device of claim 10, where the MIMO-capable interface comprises a wireless local area network (WLAN) interface compliant with Institute of Electrical and Electronic Engineers (IEEE)-Std. 802.11n, and the at least one other interface comprises a personal area network (PAN) interface capable of operating in substantially the same frequency spectrum as the MIMO-enabled interface.

12. The wireless device of claim 10, where the radio frequency isolation is caused by a physical layout of the wireless device.

13. The wireless device of claim 10, where the radio frequency isolation is determined based on an attenuator setting.

14. The method of claim 13, wherein the attenuator setting is obtained from front end radio circuitry of at least one of the MIMO-capable interface and the one other air interface.

15. The wireless device of claim 10, further comprising determining a static radio frequency isolation.

16. The wireless device of claim 10, wherein the communication uses a hardware-based signal.

17. The wireless device of claim 10, wherein the communication uses a software message.

18. The wireless device of claim 10, wherein when the radio frequency isolation is classified as asymmetric, then the first number of antenna elements is 1.

19. A wireless device, comprising:

a multi-input multi-output (MIMO)-capable air interface;

at least one other air interface;

logic configured to communicate from the one other air interface to the MIMO-capable interface a communication activity level relating to the one other air interface;

logic configured to, responsive to the communication, determine a time variant radio frequency isolation between the at least two antenna elements of the MIMO-capable interface and the one other air interface;

logic configured to classify said time variant radio frequency isolation as one of symmetric or asymmetric; and

based at least in part on the communicated communication activity level and the determined time variant radio frequency isolation, logic to configure the MIMO-capable interface to operate a first number of the antenna elements.