Enhanced handoff signaling for high speed data and multimedia

• US 6,205,128 B1
• Filed: 01/07/1998
• Issued: 03/20/2001
• Est. Priority Date: 01/07/1998
• Status: Expired due to Fees

• Current Assignee: Amosmet Investments LLC (Intellectual Ventures LLC)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Le, Khiem
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Pezzlo, John
• Application Number:
  US09/004,086
• Time in Patent Office: 1,168 Days
• Field of Search: 455/422, 455/436, 455/438, 455/439, 370/328, 370/331, 370/336, 370/335, 370/348, 370/349, 370/400, 370/338, 379/57, 379/88.15
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0066 of control information between different types of networks in order to establish a new radio link in the target network

Abstract

An enhanced handoff signaling method is disclosed that provides a short negotiation time by avoiding the need to downgrade and upgrade, provides greater efficiency by preventing calls from being dropped due to unsuccessful negotiation after the mobile station has moved to the target system, and minimizes the signaling load on the spectrum during handoff negotiations. The method includes the steps of negotiating air interface attributes that the target system can grant, sending a single message to the mobile station to order the mobile station to execute a handoff and to convey granted air interface attributes to the mobile station and executing a handoff of the mobile station to channels on the target system in accordance with the granted air interface attributes. Accordingly, a channel is not dropped even when the target system supports air interface attributes different from the source system. Further, the negotiating is performed solely over wireline links between the source system and the target system, and no negotiation involving the mobile station is required.

Claims

1. A method for executing an enhanced handoff between a source system and a target system of a current call for a mobile station, the source system and the target system possibly having dissimilar air interface attributes, the method comprising the step of:

providing a proxy source system to negotiate with the target system on behalf of the mobile station;

negotiating air interface attributes that the target system can grant, wherein all needed information is sent by the proxy source system to the target system in a single data message;

sending a single message from the proxy source system to the mobile station to order the mobile station to execute a handoff and to convey granted air interface attributes to the mobile station; and

executing a handoff of the mobile station to channels on the target system in accordance with the granted air interface attributes.

2. The method of claim 1 wherein the step of sending the target system a single signaling message comprises the step of advertising ASC and capabilities of the mobile station.

3. The method of claim 1 wherein the step of negotiating further comprises the steps of:

advertising to the target system by the source system service attributes of the current call and mobile station capabilities;

determining by the target system whether the target system can grant air interface attributes that satisfy the service attributes and that are compatible with the capabilities of the mobile station; and

returning a signaling message to the source system representing air interface attributes granted by the target system in response to a positive identification of air interface attributes that satisfy the service attributes and that are compatible with the capabilities of the mobile station.

4. The method of claim 1 wherein the step of negotiating further includes the step of eliminating signaling between the mobile station and the source system to reduce a signaling load on a wireless link.

5. The method of claim 1 wherein the step of negotiating further includes the step of eliminating signaling between the mobile station and the target system to reduce a signaling load on a wireless link.

6. The method of claim 3 further comprising the step of returning a signaling message to the source system from the target system indicating rejection in response to a negative identification of air interface attributes that satisfy the service attributes and that are compatible with the capabilities of the mobile station.

7. The method of claim 3 wherein the step of advertising includes indicating to the target system air interface attributes that result in service disruption.

8. The method of claim 1 wherein the handoff is permitted even when the target system has air interface attributes different from the air interface attributes of the source system.

9. The method of claim 1 wherein the source system provides a first set of air interface attributes and wherein the granted air interface attributes by the target system result in a quality of service more compatible to the preferred service attributes than the first set of air interface attributes provided by the source system prior to the handoff.

10. The method of claim 1 wherein the granted air interface attributes, service attributes, and MS capabilities are coded in the form of an option value.

11. The method of claim 10 wherein the option value reduces signaling delay by keeping signaling messages short.

12. The method of claim 1 wherein the step of negotiating is performed over wireline links between the source system and the target system.

13. The method of claim 3 further comprises the step of determining the mobile station capabilities once at the beginning of the call from a service subscription profile downloaded from a HLR or from information received directly from the mobile station.

14. The method of claim 13 further comprising the step of passing the mobile station capabilities from the source system to the target system at a subsequent handoff after the handoff is executed.

15. The method of claim 1 wherein the step of sending a single message to convey granted air interface attributes further comprises the step of concisely conveying the granted air interface attributes in the form of a Boolean flag when the granted air interface attributes do not differ from air interface attributes of the source system.