Dynamic adjustment of keep-alive messages for efficient battery usage in a mobile network

1. A method of maintaining an IP connection between a mobile terminal and a network node in a network, comprising:

sending, by a first mobile terminal to a first network node, keep-alive messages in an absence of network traffic through the IP connection between the first mobile terminal and the first network node in a first network;

monitoring the lengths of several periods of inactivity at which the first mobile network node disconnects the IP connection,

wherein a maximum interval between keep-alive messages is determined based on the several monitored lengths of periods of inactivity such that the maximum interval meets a predetermined criterion of statistical confidence;

storing the maximum determined interval in the first mobile terminal;

providing the maximum determined interval to a second mobile terminal prior to the second mobile terminal connecting to a second network node in a second network,

wherein the second mobile terminal sends keep-alive messages at the maximum determined interval.

2. The method of claim 1 , wherein the first network is a home network for the first mobile terminal.

3. The method of claim 1 , wherein the second network is a foreign network for the first mobile terminal.

4. The method of claim 1 , wherein the second network is a foreign network for the second mobile terminal.

5. The method of claim 1 , further comprising storing the maximum determined interval at the first mobile terminal and in association with an identifier of the first network.

6. The method of claim 1 , wherein meeting a predetermined criterion of statistical confidence includes subtracting a safety margin from the detected maximum inactivity period.

7. The method of claim 6 , wherein the safety margin is expressed in minutes.

8. The method of claim 6 , wherein the safety margin is expressed as a percentage.

9. The method of claim 6 , wherein the safety margin is proportional to the predictability of behavior of the first network.

10. The method of claim 6 , wherein the safety margin corresponds to a cost associated with the first mobile terminal.

11. The method of claim 10 , wherein the cost corresponds to battery life of the first mobile terminal.

12. The method of claim 10 , wherein the cost corresponds to a tariff for sending keep-alive messages from the first mobile terminal.

13. A computer implemented method of operating a network comprising:

determining, for a first mobile terminal, a keep-alive message interval, wherein the keep-alive message interval defines a maximum time interval between sending keep-alive messages between the first mobile terminal and a first network node over a first network in order to prevent disconnection of a first Internet Protocol connection between the first mobile terminal and the first network node;

determining, for the first mobile terminal, a keep-alive message schedule for sending keep-alive messages over a period of time, wherein the keep-alive message schedule is based on the keep-alive message interval;

storing the keep-alive message schedule in the first mobile terminal;

providing, to a second mobile terminal, the keep-alive message schedule prior to the second mobile terminal connecting to a second network node over a second network,

wherein the second mobile device sends keep-alive messages based on the keep-alive message schedule in order to maintain a second Internet Protocol connection between the second mobile terminal and the second network node.

14. A network-node device comprising:

a communication interface operable to communicatively couple the network-node device to a network; and

a processor and a memory storing program codes, coupled to the communication interface, operable to:

determine, for a first mobile terminal, a keep-alive message interval, wherein the keep-alive message interval defines a maximum time interval between sending keep-alive messages between the first mobile terminal and a first network node over a first network in order to prevent disconnection of a first Internet Protocol connection between the first mobile terminal and the first network node;

determine, for the first mobile terminal, a keep-alive message schedule for sending keep-alive messages over a period of time, wherein the keep-alive message schedule is based on the keep-alive message interval;

store, in the first mobile terminal, the keep-alive message schedule; and

provide, to a second mobile terminal, the keep-alive message schedule prior to the second mobile terminal connecting to a second network node over a second network,

send, from the second mobile terminal, keep-alive messages based on the keep-alive message schedule in order to maintain a second Internet Protocol connection between the second mobile terminal and the second network node.

15. The network-node device of claim 14 , the processor and memory further operable to:

monitor periods of inactivity between the first mobile terminal and the first network node.

16. The network-node device of claim 15 , the processor and memory further operable to:

detect a rate with which content requested from the second mobile terminal is changing; and

dynamically adjust time intervals between sending the keep-alive messages based on the rate with which the content is changing and a cost to send the keep-alive messages in the network, wherein the cost includes re-establishing the second Internet Protocol connection in event of disconnection.

17. The network-node device of claim 14 , the processor and memory further operable to:

determine a network identifier for the first mobile terminal; and

associate keep-alive message schedule with the network identifier.

18. The network-node device of claim 16 , wherein the cost corresponds to a battery life of the second mobile terminal.

19. The network-node device of claim 14 , wherein the determined keep-alive message interval and keep-alive message schedule override default keep-alive message information.

20. The network-node device of claim 14 , wherein:

the first mobile terminal is a first cellular phone, and the second mobile terminal is a second cellular phone.