METHOD AND APPARATUS FOR ROBUST HANDOFF IN WIRELESS COMMUNICATION SYSTEMS

• US 20070105584A1
• Filed: 01/03/2007
• Published: 05/10/2007
• Est. Priority Date: 09/22/1998
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Padovani, Roberto, Karmi, Gadi, Kimball, Robert, Bender, Paul, Grob, Matthew, Hoagland, Greg
• Granted Patent: US 8,588,777 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data

Abstract

A communication system that allows a soft handoff to be completed, even when the communications link between the active base station and the mobile station deteriorates before the mobile station has received the handoff direction message. The mobile station maintains a list of base stations that the mobile station is in communication with, referred to as an “Active Set”. In addition, the mobile station maintains another list of base stations that are proximate to the base stations in the active set. This list is referred to as the “Neighbor Set”. In accordance with the disclosed method and apparatus, the mobile station places a base station in the active set upon including the base station in a pilot strength measurement message (PSMM). The mobile station monitors transmissions from all of the base stations on the active set to receive a handoff direction message (HDM).

Claims

1. An apparatus adapted for wires communications, comprising:

means for measuring powers of signals transmitted from a plurality of base station transceivers;

means for identifying each base station transceiver whose measured signal power is greater than a threshold;

means for placing indicators of said identified base station transceivers to a first set;

means for transmitting the indicators; and

means for receiving a direction message from at least one of the identified base station transceivers not in communication with a mobile station via a traffic channel.

2. The apparatus of claim 1, further comprising means for adjusting the indicators in the first set in accordance with the received direction message.

3. The apparatus of claim 1, further comprising means for determining indicators of said identified base station transceivers not included in the first set.

4. The apparatus of claim 1, further comprising means for establishing a traffic channel with the at least one of the identified base station transceivers not in communication with the mobile station.

5. The apparatus of any one of claims 1 to 4, wherein the apparatus comprises a computer program product to increase efficiency in wires communications, when coupled to a computing device.

6. A method for wireless communications, comprising:

measuring powers of signals transmitted from a plurality of base station transceivers;

identifying each base station transceiver whose measured signal power is greater than a threshold;

placing indicators of said identified base station transceivers to a first set;

transmitting the indicators; and

receiving a direction message from at least one of the identified base station transceivers not in communication with the mobile station via a traffic channel.

7. The method of claim 6, further comprising adjusting the indicators in the first set in accordance with the received direction message.

8. The method of claim 6, further comprising determining indicators of said identified base station transceivers not included in the first set.

9. The method of claim 6, further comprising establishing a traffic channel with the at least one of the identified base station transceivers not in communication with the mobile station.

10. A computer program product, comprising:

code for measuring powers of signals transmitted from a plurality of base station transceivers;

code for identifying each base station transceiver whose measured signal power is greater than a threshold;

code for placing indicators of said identified base station transceivers to a first set;

code for transmitting the indicators; and

code for receiving a direction message from at least one of the identified base station transceivers not in communication with a mobile station via a traffic channel.

11. The computer program product of claim 10, further comprising code for adjusting the indicators in the first set in accordance with the received direction message.

12. The computer program product of claim 10, further comprising code for determining indicators of said identified base station transceivers not included in the first set.