Method and system for soft handoff in mobile broadband systems

• US 8,437,761 B2
• Filed: 06/13/2011
• Issued: 05/07/2013
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Senarath, Nimal, Gage, Bill, Periyalwar, Shalini, Tong, Wen
• Primary Examiner(s): Nguyen, David Q
• Application Number:
  US13/159,023
• Publication Number:
  US 20110237262A1
• Time in Patent Office: 694 Days
• Field of Search: 455/442, 455/436, 455/435.1, 455/435.2, 455/439, 455/453, 370/320, 370/331
• US Class Current: 455/442
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/20 for optimising the interference level
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 80/02 Data link layer protocols

Abstract

The present invention provides a method and system for facilitating efficient handoff and data throughput in mobile broadband communication systems. Methods implemented by a system constructed in accordance with the principles of the present invention include selectively enabled soft handoff, performing Layer 2 bearer functions at the base station and using the mobile device to coordinate soft handoff and interference avoidance without the need for a centralized coordination function.

Claims

1. A mobile device for wirelessly communicating in a broadband system supporting soft handoff for a service, the broadband system having a plurality of base station transceiver systems, the mobile device comprising:

a buffer configured to receive information indicating available resource units determined by the plurality of base station transceiver systems; and

a processor configured to;

compare the available resource units and select available resource units for transmitting a data flow;

determine that the service is eligible for soft handoff, wherein said determining comprises determining whether a data flow associated with the service is eligible for soft handoff; and

activate soft handoff for eligible data flows corresponding to the eligible service while not activating soft handoff for ineligible data flows.

2. The mobile device according to claim 1, wherein the processor is further configured to:

determine an active set of base station transceivers eligible to support the soft handoff from the plurality of base station transceivers, wherein a base station transceiver is eligible for inclusion in the active set based on one of a data flow and an eligible service, wherein different data flows are supported by one or more different active sets of base station transceivers.

3. The mobile device according to claim 2, wherein, prior to using the service, the mobile device notifies selected base station transceiver systems that the service is a High-QoS service.

4. The mobile device according to claim 3, wherein the High-QoS service uses soft handoff.

5. The mobile device according to claim 1, wherein the processor identifies whether the service is eligible for soft handoff by monitoring the data flow corresponding to the service.

6. The mobile device according to claim 1, wherein the processor is further configured to:

determine a C/I ratio of the channel supporting the service;

establish a soft handoff trigger for the service at which soft handoff will be activated, the soft handoff trigger being based on one or more of a C/I ratio, received signal strength from one or more base station transceivers, base station transceiver loading, mobile device velocity and location, and type of service; and

activate soft handoff if the trigger for the service occurs.

7. The mobile device according to claim 1, wherein a quantity of the plurality of base station transceiver systems in communication for SHO for a selected mobile device is determined using a signal strength from at least one of the plurality of base station transceiver, base station transceiver loading and a service requirement of the data flow.

8. The mobile device according to claim 1, wherein the data flow is comprised of one or more packets, each packet including a header indicating to the processor whether the packet is in soft handoff.

9. A non-transitory, computer accessible memory medium storing program instructions for wirelessly communicating in a broadband system supporting soft handoff for a service, the broadband system having a plurality of base station transceiver systems, wherein the program instructions are executable to:

receive available resource units determined by the plurality of base station transceiver systems;

compare the available resource units and select available resource units for transmitting a data flow; and

determine that the service is eligible for soft handoff, wherein said determining that the service is eligible for soft handoff comprises determining whether a data flow associated with the service is eligible for soft handoff and wherein the program instructions are further executable to activate soft handoff for eligible data flows corresponding to the eligible service while not activating soft handoff for ineligible data flows.

10. The non-transitory, computer accessible memory medium according to claim 9, wherein the data flow is comprised of one or more packets, each packet including a header indicating to the processor whether the packet is in soft handoff.

11. The non-transitory, computer accessible memory medium according to claim 9, wherein an active set of base station transceivers eligible to support the soft handoff is determined from the plurality of base station transceivers, wherein a base station transceiver is eligible for inclusion in the active set based on one of a data flow and an eligible service, wherein different data flows are supported by one or more different active sets of base station transceivers.

12. The non-transitory, computer accessible memory medium according to claim 11, wherein, prior to using the service, the mobile device notifies selected base station transceiver systems that the service is a High-QoS service.

13. The non-transitory, computer accessible memory medium according to claim 12, wherein the High-QoS service uses soft handoff.

14. The non-transitory, computer accessible memory medium according to claim 9, wherein the program instructions are further executable to identify whether the service is eligible for soft handoff by monitoring the data flow corresponding to the service.

15. The non-transitory, computer accessible memory medium according to claim 9, wherein the program instructions are further executable to:

determine a C/I ratio of the channel supporting the service;

establish a soft handoff trigger for the service at which soft handoff will be activated, the soft handoff trigger being based on one or more of a C/I ratio, received signal strength from one or more base station transceivers, base station transceiver loading, mobile device velocity and location, and type of service; and

activate soft handoff if the trigger for the service occurs.

16. The non-transitory, computer accessible memory medium according to claim 9, wherein the program instructions are further executable to:

determine the plurality of base station transceiver systems, wherein said determining comprises using a signal strength from at least one of the plurality of base station transceiver, base station transceiver loading and a service requirement of the data flow.

17. A method for wirelessly communicating in a broadband system supporting soft handoff for a service, the broadband system having a plurality of base station transceiver systems, wherein the method comprises:

a mobile device receiving available resource units determined by the plurality of base station transceiver systems;

the mobile device comparing the available resource units and select available resource units for transmitting a data flow;

the mobile device determining that the service is eligible for soft handoff, wherein said determining that the service is eligible for soft handoff comprises determining whether a data flow associated with the service is eligible for soft handoff; and

the mobile device activating soft handoff for eligible data flows corresponding to the eligible service while not activating soft handoff for ineligible data flows.

18. The method according to claim 17, wherein the data flow is comprised of one or more packets, each packet including a header indicating to the processor whether the packet is in soft handoff.

19. The method according to claim 17, further comprising:

determining an active set of base station transceivers eligible to support the soft handoff from the plurality of base station transceivers, wherein a base station transceiver is eligible for inclusion in the active set based on one of a data flow and an eligible service, wherein different data flows are supported by one or more different active sets of base station transceivers.

20. The method according to claim 19, wherein, prior to using the service, the mobile device notifies selected base station transceiver systems that the service is a High-QoS service.

21. The method according to claim 20, wherein the High-QoS service uses soft handoff.

22. The method according to claim 17, further comprising:

identifying whether the service is eligible for soft handoff by monitoring the data flow corresponding to the service.

23. The method according to claim 17, further comprising:

determining a C/I ratio of the channel supporting the service;

establishing a soft handoff trigger for the service at which soft handoff will be activated, the soft handoff trigger being based on one or more of a C/I ratio, received signal strength from one or more base station transceivers, base station transceiver loading, mobile device velocity and location, and type of service; and

activating soft handoff if the trigger for the service occurs.

24. The method according to claim 17, further comprising:

determining the plurality of base station transceiver systems, wherein said determining comprises using a signal strength from at least one of the plurality of base station transceiver, base station transceiver loading and a service requirement of the data flow.

25. A mobile device for wirelessly communicating in a broadband system supporting soft handoff for a service, the broadband system having a plurality of base station transceiver systems, the mobile device comprising:

at least one antenna for performing wireless communication; and

processing hardware coupled to the antenna, wherein the processing hardware is configured to;

request available resource units from the plurality of base station transceiver systems via the at least one antenna;

in response to the request, receive the available resource units, as determined by the plurality of base station transceiver systems, via the at least one antenna;

compare the available resource units and select available resource units for transmitting a data flow;

determine that the service is eligible for soft handoff, wherein said determining that the service is eligible for soft handoff comprises determining whether a data flow associated with the service is eligible for soft handoff; and

activate soft handoff for eligible data flows corresponding to the eligible service while not activating soft handoff for ineligible data flows.