Handoff method in CDMA communication system

• US 20060013165A1
• Filed: 09/20/2005
• Published: 01/19/2006
• Est. Priority Date: 10/24/2000
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Chang, Woon Suk, Choi, Young Su
• Granted Patent: US 7,529,208 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0033 with transfer of context information
• CPC Class Codes: H04W 36/0069 in case of dual connectivity, e.g. decoupled uplink/downlink
• CPC Class Codes: H04W 36/28 involving a plurality of connections, e.g. multi-call or multi-bearer connections

Abstract

A handoff method in a CDMA system is performed when a mobile station with dormant packet data call is handed off to an area where the packet zone identifier is changed. The method includes call connection handoffing first information from first base station to second base station by a mobile station, comparing first packet zone identifier about the call of second information transmitted from the second base station with second packet zone identifier about the call of the second information maintained by the mobile base station, and transmitting a call setting message of the second information from the mobile station to the second base station to request a handoff of the second information if the identifiers are different. Therefore, an In-traffic System Parameter message is used, thereby excluding the need for additional hardware.

Claims

1. A method of handoff in a CDMA communication system, comprising:

executing a handoff of a call connection of a first information call of a mobile station from a first base station to a second base station;

comparing a packet zone identifier of a second information call transmitted from the second base station with a packet zone identifier maintained by the mobile station; and

transmitting a call initializing message of the second information call from the mobile station to the second base station to request a handoff of the second information call if the packet zone identifiers are different.

2. The method of claim 1, wherein the second information call is dormant.

3. The method of claim 1, wherein the second information is packet data.

4. The method of claim 1, wherein an information transmission connection with the second base station is initialized after the mobile station completes an information transmission connection with the first base station in said handoff execution step from the first base station to the second base station.

5. The method of claim 1, wherein the packet zone identifier is transmitted from the second base station to the mobile station via a message in the information transmitted from the second base station.

6. The method of claim 5, wherein the message in the transmitted information is an in-traffic system parameter.

7. A method of performing a handoff in a communication system, comprising:

performing a handoff of a first call of a subscriber unit from a first fixed station to a second fixed station;

receiving an In-traffic System Parameter Message having a packet zone identifier from the second fixed station over an air interface;

comparing the packet zone identifier of the second fixed station transmitted in the In-traffic System Parameter Message with a packet zone identifier of the first fixed station stored in the subscriber unit to perform a handoff of a concurrent second call, wherein the first call is an active call and the second call is a dormant packet data call.

8. The method of claim 7, further comprising transmitting an acknowledge order from the subscriber unit to the second fixed station to acknowledge receipt of the In-traffic System Parameter Message.

9. The method of claim 8, further comprising transmitting a Handoff Complete message from the second fixed station to a switching center associated with the first and second fixed stations to indicate that the handoff is complete.

10. The method of claim 7, wherein an information transmission connection with the second fixed station is initialized after the subscriber unit releases an information transmission connection with the first fixed station after the handoff of the concurrent second call from the first fixed station to the second fixed station.

11. The method of claim 7, wherein the first call is one of a packet service call and a circuit service call.

12. The method of claim 7, wherein the handoff of the second information call is completed using a Packet Control Function.

13. The method of claim 7, wherein the second information call uses a Point-to-Point Protocol (PPP) to communicate with a Packet Data Serving Node.

14. The method of claim 7, wherein performing a handoff of a first call comprises:

transmitting a handoff required message from the first fixed station to a switching center to determine if a handoff is necessary;

transmitting a Handoff Request message from the switching center to the second fixed station to request a handoff to the second fixed station if a handoff is necessary;

transmitting Null Forward Traffic frames from the second fixed sation to the subscriber unit to assist in acquiring the subscriber unit by the second fixed sation;

transmitting a Handoff Request Acknowledge message from the second fixed station to the switching center to acknowledge receipt of the Handoff Request message;

transmitting a Handoff Command message from the switching center to the first fixed station to initiate the handoff;

transmitting a Handoff Direction message from the first fixed station to the subscriber unit to inform the subscriber unit of the handoff;

transmitting an Acknowledge Order message from the subscriber unit to the first fixed station to acknowledge receipt of the Handoff Direction message;

transmitting a Handoff Commenced message from the first fixed station to the mobile switch to indicate that the handoff has commenced;

transmitting at least one of Reverse Traffic Channel Frames and a Preamble from the subscriber unit to the second fixed station;

transmitting a Handoff Completion message from the subscriber unit to the to the second fixed station to indicate that the handoff has been completed; and

transmitting an Acknowledge Order message from the second fixed station to the subscriber unit to acknowledge receipt of the Handoff Completion message.

15. The method of claim 14, further comprising:

transmitting an Acknowledge Order message from the subscriber unit to the second fixed station after receiving the In-traffic System Parameter Message to acknowledge receipt of the In-traffic System Parameter Message;

transmitting a Handoff Complete message from the second fixed station to the switching center to indicate that the handoff is complete;

transmitting a Clear Command message from the mobile switch to the first fixed station to inform the first fixed station that the subscriber unit may be cleared from the first fixed sation; and

transmitting a Clear Complete message from the first fixed station to the switching center to indicate that the subscriber unit has been cleared from the first fixed station.

16. The method of claim 7, wherein communication system is a CDMA communication system.

17. The method of claim 7, further comprising transmitting a call initializing message of the second packet data call from the subscriber unit to the second fixed station to request a dormant handoff of the second information call if the packet zone identifiers of the first and second fixed stations are different.