DEVICE AND METHOD FOR MAINTAINING A COMMUNICATION SESSION DURING A NETWORK TRANSITION

• US 20090086681A1
• Filed: 09/03/2008
• Published: 04/02/2009
• Est. Priority Date: 09/03/2007
• Status: Active Grant

• Current Assignee: Damaka, Inc.
• Original Assignee: Damaka, Inc.
• Inventors: CHATURVEDI, SIVAKUMAR R., GUNDABATHULA, SATISH
• Granted Patent: US 8,437,307 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04L 61/2553 Binding renewal aspects, e.g. using keep-alive messages
• CPC Class Codes: H04L 61/2575 using address mapping retrieval, e.g. simple traversal of user datagram protocol through session traversal utilities for NAT [STUN]
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 76/19 Connection re-establishment

Abstract

Provided are a device and method for maintaining a communication session during a network transition. In one example, the method includes monitoring, by a client, a connection with a first network to determine whether a signal strength of the connection falls below a threshold value. The client establishes a connection with a second network if the signal strength of the connection with the first network falls below the threshold value. Establishing the connection with the second network includes obtaining an address and port assignment corresponding to the client from the second network. The client uses the obtained address and port assignment to maintain a communication session during the changeover from the first network to the second network.

Claims

1. A method comprising:

monitoring, by a client, a first connection with a first network to determine whether a signal strength of the first connection falls below a threshold value;

establishing, by the client, a second connection with a second network if the signal strength of the first connection falls below the threshold value, wherein establishing the second connection includes obtaining an address and port assignment corresponding to the client from the second network; and

maintaining, by the client, a communication session during the changeover from the first connection to the second connection using the obtained address and port assignment.

2. The method of claim 1 further comprising determining whether a signal strength between the client and the second network exceeds the threshold, wherein establishing the second connection occurs only if the signal strength between the client and the second network exceeds the threshold.

3. The method of claim 1 further comprising:

determining, by the client, a rate at which the signal strength of the first connection is weakening; and

establishing, by the client, the second connection based on the rate at which the signal strength of the first connection is weakening even if the signal strength of the first connection has not fallen below the threshold value.

4. The method of claim 1 wherein maintaining the communication session includes reestablishing the communication session via the second network after establishing the second connection.

5. The method of claim 4 further comprising breaking the first connection prior to establishing the second connection.

6. The method of claim 4 further comprising breaking the first connection after establishing the second session.

7. The method of claim 1 wherein maintaining the communication session includes:

saving a current state of the client prior to terminating the first connection;

using the saved state to maintain the communication session via the second connection; and

refreshing the saved state with a new current state obtained after the changeover, wherein the refreshing updates the client with information not received by the client during the changeover.

8. A method comprising:

determining, by a client, whether a signal strength of a first connection with a first network has fallen below a threshold value;

saving, by the client, a current state of the client, wherein the current state identifies information corresponding to a communication session occurring between the client and an endpoint via the first connection;

establishing, by the client, a second connection with a second network if the signal strength of the first connection falls below the threshold value, wherein establishing the second connection includes obtaining an address and port assignment corresponding to the client from the second network;

sending, by the client, a notification directly to the endpoint to notify the endpoint of the address and port assignment corresponding to the client in the second network, wherein contact information needed to communicate directly with the endpoint is contained in the saved current state;

continuing, by the client, the communication session via the second connection based on the saved current state; and

refreshing the saved current state with a new state obtained from an access server via the second connection, wherein the refreshing updates the current state of the client with information not received by the client while switching from the first connection to the second connection.

9. The method of claim 8 further comprising sending, by the client, a STUN request to a STUN server after establishing the second connection to obtain natural address translation information related to the client.

10. The method of claim 9 further comprising updating the new state with the obtained natural address translation information.

11. The method of claim 8 further comprising determining whether a signal strength between the client and the second network exceeds the threshold, wherein establishing the second connection occurs only if the signal strength between the client and the second network exceeds the threshold.

12. The method of claim 8 further comprising:

determining, by the client, a rate at which the signal strength of the first connection is weakening; and

establishing, by the client, the second connection based on the rate at which the signal strength of the first connection is weakening even if the signal strength of the first connection has not fallen below the threshold value.

13. The method of claim 8 wherein continuing the communication session includes reestablishing the communication session via the second network after establishing the second connection.

14. The method of claim 13 further comprising breaking the first connection prior to establishing the second connection.

15. The method of claim 13 further comprising breaking the first connection after establishing the second session.

16. The method of claim 8 further comprising terminating the communication session if the second connection cannot be established within a defined time window.

17. A device comprising:

a network interface;

a processor coupled to the network interface;

a memory coupled to the processor; and

a plurality of instructions stored in the memory for execution by the processor, the instructions including instructions for;

determining, by the device, whether a signal strength of a first connection established with a first network via the network interface has fallen below a threshold value;

saving, by the device, a current state of the device, wherein the current state identifies information corresponding to a communication session between the device and an endpoint occurring via the first connection;

establishing, by the device, a second connection with a second network via the network interface if the signal strength of the first connection falls below the threshold value, wherein establishing the second connection includes obtaining an address and port assignment corresponding to the device from the second network;

sending, by the device, a notification directly to the endpoint via the network interface to notify the endpoint of the address and port assignment corresponding to the device in the second network, wherein contact information needed to communicate directly with the endpoint is contained in the saved current state;

continuing, by the device, the communication session via the second connection based on the saved current state; and

refreshing the saved current state with a new state obtained from an access server via the second connection, wherein the refreshing updates the current state of the device with information not received while switching from the first connection to the second connection.

18. The device of claim 17 wherein the instructions further comprise instructions for determining whether a signal strength between the device and the second network exceeds the threshold, wherein establishing the second connection occurs only if the signal strength between the device and the second network exceeds the threshold.

19. The device of claim 17 wherein the instructions further comprise:

determining, by the device, a rate at which the signal strength of the first connection is weakening; and

establishing, by the device, the second connection based on the rate at which the signal strength of the first connection is weakening even if the signal strength of the first connection has not fallen below the threshold value.