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

• US 20090323652A1
• Filed: 06/26/2008
• Published: 12/31/2009
• Est. Priority Date: 06/26/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Robinson, Michael A., Chen, Camille, Giles, Michael J.
• Granted Patent: US 8,284,721 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• 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 wireless device having at least first and second air interfaces, said first air interface comprising at least two antenna elements, said second interface comprising another antenna element, said method comprising:

determining the isolation between individual ones of said at least two antenna elements of said first interface and said another antenna element of said second interface;

selecting at least one of said at least two elements of said first interface for operation; and

simultaneously operating said first and second interfaces within a common frequency band using said selected one of said at least two elements of said first interface, and said another element of said second interface, respectively.

2. The method of claim 1, wherein said isolation between said first antenna element of said at least two antenna elements of said first interface and said another antenna element of said second interface is substantially unequal to that between said second antenna element and said another antenna element.

3. The method of claim 2, wherein said first interface comprises a high data rate WLAN interface, and said second interface comprises a lower data rate personal area networking (PAN) interface, and said simultaneously operating comprises operating within a band comprising a frequency of 2.4 GHz.

4. The method of claim 3, wherein said act of selecting comprises operating one antenna element circuit associated with the selected antenna element, and not operating the antenna element circuit associated with the non-selected ones of said at least two elements.

5. The method of claim 1, wherein said simultaneously operating comprises simultaneously operating without use of a time-sharing or time-divided spectral access scheme.

6. The method of claim 3, wherein the placement of said at least two antenna elements of said first interface and said another antenna element of said second interface within said wireless device does not permit isolation levels between said at least two elements and said another element sufficient for simultaneous operation of all of said at least two elements and said another element without significant degradation of the data rate of said WLAN interface.

7. A method of operating a MIMO-capable air interface of a device having at least one additional air interface, the method comprising:

communicating from said one other air interface to said MIMO-capable interface communication activity level on said one other air interface;

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

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

8. The method of claim 7, wherein said determining comprises determining a static isolation.

9. The method of claim 8, wherein said determining is responsive to physical layout of antennae of said device.

10. The method of claim 7, wherein said determining comprises determining a time-variant isolation.

11. The method of claim 10, wherein said determining is based at least in part on an attenuator setting.

12. The method of claim 11, wherein said attenuator setting is obtained from front end radio circuitry of at least one of said MIMO-capable interface and said one additional interface.

13. The method of claim 7, wherein said communicating comprises communicating using a hardware-based signal.

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

15. The method of claim 7, further comprising classifying said radio frequency isolation as one of symmetric or asymmetric.

16. The method of claim 15, wherein if said radio frequency isolation is classified as asymmetric, then said first number of antenna elements is 1.

17. Apparatus having multiple air interfaces, comprising:

a plurality of first antenna elements configured to communicate on a first air interface;

at least one second antenna element configured to communicate on a second air interface;

first front end circuitry operatively coupled with said plurality of first antenna elements, said circuitry enabling transmitting and receiving signals over said first interface;

second front end circuitry operatively coupled with said at least one second antenna element, said second circuitry enabling transmitting and receiving signals over said second interface;

a communication channel between said interface and said second interface and adapted to carry activity information; and

a processor communicatively coupled to said first front end circuit and said second front end circuit;

said processor configured to;

determine the isolation between antennae pairs formed from said plurality of first antenna elements and said at least one second antenna element;

evaluate whether said isolations are symmetric or asymmetric; and

based at least in part on said evaluation, not using of at least one antenna element from said plurality of first antennae.

18. The apparatus of claim 17, wherein said first front end circuitry comprises front end circuits for each of said antenna elements of said plurality, and said not using comprises turning off at least a portion of said front end circuits.

19. The apparatus of claim 17, wherein said not using comprises not using if said isolations are evaluated to be asymmetric.

20. The apparatus of claim 17, wherein said apparatus comprises a portable computerized device having a substantially metallic outer case.

21. The apparatus of claim 17, wherein said first interface comprises a WLAN interface having MIMO capability, and said second interface comprises a personal area network (PAN) interface.

22. The apparatus of claim 21, wherein the placement of said plurality of first antenna elements of said WLAN interface and said at last one second antenna element of said PAN interface within said apparatus does not permit isolation levels between said plurality of first elements and said at least one second element sufficient for simultaneous operation of all of said plurality of first elements and said at least one second element without significant degradation of the data rate of said WLAN interface.

23. The apparatus of claim 17, wherein said processor is configured to detect said isolations as a function of at least one of:

(i) the physical placement of said plurality of first antenna elements;

(ii) an operational setting of said first front end circuitry; and

(iii) an operational setting of said second front end circuitry.

24. The apparatus of claim 17, wherein said communication channel comprises one or more hardware-based channels adapted to carry signals from said second interface to said first interface.

25. Wireless portable apparatus adapted for data communication over first and second air interfaces, the apparatus comprising:

a first air interface having at least two antennae associated therewith;

a second air interface having at least one antenna associated therewith, said first and second air interfaces operating in a substantially overlapping frequency band, said at least two antenna of said first interface being disposed within said apparatus asymmetrically with respect to their isolations with said at least one antenna of said second interface;

a processor; and

a storage device, said storage device comprising a computer program having a plurality of instructions that when executed;

determine if the potential for interference between said first and second air interfaces exists; and

if said potential exists, turning at least one of said at least two antennae off so as to mitigate said interference.

26. The apparatus of claim 25, wherein:

said first interface comprises a MIMO wireless LAN (WLAN) interface;

said second interface comprises a personal area networking (PAN) interface; and

said turning at least one of said at least two antenna off comprises disabling transmission or reception via one of said at least two antennae that has the lowest isolation with said at least one antenna of said PAN interface.

27. The apparatus of claim 26, wherein said apparatus comprises a portable computerized device having a clamshell-like outer case, and said at least two antennae of said WLAN interface and said at least one antenna of said second interface are all disposed substantially within a hinge region of said clamshell-like case.

28. The apparatus of claim 27, wherein said outer case is substantially metallic.

29. The apparatus of claim 25, wherein said determination of the potential for interference comprises determining whether both first and second interfaces are transmitting or receiving at the same time.

30. A computer readable apparatus having a storage medium, said medium adapted to store a computer program comprising instructions which, when executed:

detect an asymmetric isolation condition by comparing the isolations between antennae of a plurality of antenna pairs associated with first and second air interfaces; and

turns on or off, responsive to said asymmetric condition, use of at least one antenna within said first interface, said first interface comprising a multi-input, multi-output (MIMO) air interface.

31. A method of doing business relating to a wireless device, the method comprising:

receiving a plurality of user inputs regarding a desired configuration of said device;

based at least in part on said inputs, determining the placement of a plurality of antennae within said device, said plurality of antenna comprising two or more antennae associated with a MIMO-enabled air interface and one or more antennae associated with a second air interface; and

configuring said device during build so as to selectively activate or deactivate at least one of said two or more antennae during conditions of simultaneous operation of said MIMO-enabled and second air interfaces so as to mitigate the effects of interference there between.

32. The method of claim 31, wherein said act of receiving comprises receiving said inputs via an Internet website.

33. The method of claim 31, wherein said act of receiving comprises receiving said inputs requiring said device to have at least said MIMO-enabled interface and said second interface, said MIMO-enabled interface comprising a WLAN interface compliant with IEEE-Std. 802.11n, and said second interface comprising a PAN interface capable of operating in substantially the same frequency spectrum as said MIMO-enabled interface.

34. The method of claim 31, wherein said act of determining the placement comprises determining a placement wherein the isolation between individual ones of said two or more antenna of said MIMO-enabled interface and said one or more antennae of said second interface is not equal.

35. The method of claim 31, wherein said act of determining the placement is based at least in part on isolation values obtained during testing of a prototype of said device, said prototype having a substantially similar configuration to that of said wireless device as requested by said user.