METHOD AND SYSTEM FOR SOFT HANDOFF IN MOBILE BROADBAND SYSTEMS

• US 20110237262A1
• Filed: 06/13/2011
• Published: 09/29/2011
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: SENARATH, Nimal, GAGE, Bill, PERIYALWAR, Shalini, TONG, Wen
• Granted Patent: US 8,437,761 B2
• Time in Patent Office: Days
• 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 36/0072 of resource information of target access point
• 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 36/24 Reselection being triggered by specific parameters
• 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 that receives available resource units from the plurality of base station transceiver systems; and

a processor operating to;

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.

2. The mobile device according to claim 1, wherein the processor determines that the service is eligible for soft handoff by determining whether a data flow associated with the service is eligible for soft handoff and wherein the processor activates soft handoff only for eligible data flows corresponding to the eligible service.

3. The mobile device according to claim 1, 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.

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

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

6. 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.

7. The mobile device according to claim 1, wherein the processor further operates 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.

8. 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.

9. The mobile device according to claim 2, 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.