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

• US 8,284,721 B2
• Filed: 06/26/2008
• Issued: 10/09/2012
• 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): HSU, ALPUS
• Application Number:
  US12/215,574
• Publication Number:
  US 20090323652A1
• Time in Patent Office: 1,566 Days
• Field of Search: 370/329, 370/334, 370/338, 370/463, 370/465, 455/13.3, 455/63.4, 455/422.1, 455/450, 455/509
• US Class Current: 370/329
• 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. 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 first front end circuitry enabling transmitting and receiving signals over said first air interface;

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

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

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

said processor configured to;

determine an 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.

2. The apparatus of claim 1, 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.

3. The apparatus of claim 1, wherein said not using comprises not using if said isolations are evaluated to be asymmetric.

4. The apparatus of claim 1, wherein said apparatus comprises a portable computerized device having a substantially metallic outer case.

5. The apparatus of claim 1, wherein said first air interface comprises a wireless local area network (WLAN) interface having multiple-input multiple-output (MIMO) capability, and said second air interface comprises a personal area network (PAN) interface.

6. The apparatus of claim 5, 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 a data rate of said WLAN interface.

7. The apparatus of claim 1, 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.

8. The apparatus of claim 1, wherein said communication channel comprises one or more hardware-based channels adapted to carry signals from said second air interface to said first air interface.

9. 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 air interface being disposed within said apparatus asymmetrically with respect to their isolations with said at least one antenna of said second air interface;

a processor; and

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

determine if a 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.

10. The apparatus of claim 9, wherein:

said first air interface comprises a multiple-input multiple-output MIMO wireless LAN (WLAN) interface;

said second air 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 lower isolation with said at least one antenna of said PAN interface.

11. The apparatus of claim 10, 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 air interface are all disposed substantially within a hinge region of said clamshell-like case.

12. The apparatus of claim 11, wherein said outer case is substantially metallic.

13. The apparatus of claim 9, wherein said determination of the potential for interference comprises determining whether both first and second air interfaces are transmitting or receiving at the same time.

14. A method of operating a device having at least first and second air interfaces, the method comprising:

communicating on the first air interface via a plurality of first antenna elements;

communicating on the second air interface via at least one second antenna element; and

wherein the first and second air interfaces are additionally coordinating activity information via a distinct communication channel;

determining isolations between antennae pairs formed from the plurality of first antenna elements and the at least one second antenna element;

evaluating whether the isolations are symmetric or asymmetric; and

based at least in part on the evaluation, enabling a subset of the plurality of first antenna elements.

15. The method of claim 14, wherein the first air interface comprises a multiple-input multiple-output MIMO wireless LAN (WLAN) interface, and the second air interface comprises a personal area networking (PAN) interface.

16. The method of claim 15, wherein the device comprises a mobile wireless device also having a cellular air interface and an at least partly metallic outer housing.

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

a processor; and

a storage device in data communication with the processor, the storage device comprising a computer program having a plurality of instructions that are configured to, when executed on the processor;

determine when a potential for interference between the first and second air interfaces exists; and

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

18. The apparatus of claim 17, wherein:

the first air interface comprises a multiple-input multiple-output MIMO wireless LAN (WLAN) interface;

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

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