METHOD OF SELECTING TARGET NETWORK FOR HAND-OVER AND METHOD THEREOF

• US 20090219894A1
• Filed: 05/07/2009
• Published: 09/03/2009
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Eunah, Jeon, Hong-Seok, Lee, Hyeong-Ho, Jung, Heeyoung, Jee, Junghoon
• Granted Patent: US 8,730,908 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• 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
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 36/26 by agreed or negotiated communication parameters
• CPC Class Codes: H04W 36/362 Conditional handover
• CPC Class Codes: H04W 36/365 by manual user interaction
• CPC Class Codes: H04W 36/38 by fixed network equipment

Abstract

A conventional handover method is performed in units of base stations, so that there is a problem in that a large amount of power for handover is consumed and implementation cost is high.

Through dedicated protocol message exchanges between a user equipment and a network or between networks, resource availability of candidate networks is checked in advance, a handover target network is selected from among the candidate networks according to a result of checking, and the selected target network is designated as a network to which the user equipment is handed over.

Claims

1. A method of selecting a handover target network, comprising:

(a) discovering handover object networks by a user equipment which wants to execute a handover;

(b) selecting handover candidate networks from the discovered object networks by the user equipment;

(c) deciding the only handover target network from among the selected candidate networks by the user equipment; and

(d) executing the handover to the selected target network by the user equipment.

2. The method of claim 1, wherein in (a), the user equipment requests information on an object network of a network information server having the information on the object network, and the network information server transmits the information on the object network to the user equipment in response to the request.

3. The method of claim 2, wherein (b) comprises:

(b1) the user equipment determining whether it needs to be handed over;

(b2) when it is determined that the user equipment needs to be handed over, determining whether or not the information on the object network corresponds to information included in the user equipment; and

(b3) when the information on the object network corresponds to the information included in the user equipment, designating the object network as one of the candidate networks.

4. The method of claim 3, wherein in (b1), the user equipment monitors in real time quality and signal strength of the current network to which the user equipment is currently connected and quality and signal strength of the object network, and determines that a handover is needed when the quality and the signal strength of the current network decrease to less than critical values, or the quality and the signal strength of the object network increase to more than critical values.

5. The method of claim 3

wherein (b2) comprises:

(b21) determining whether or not the object network corresponds to an external network interface included in the user equipment; and

(b22) when the correspondence is determined in (b21), determining whether or not the information on the object network is included in subscribing information on the user equipment, and

wherein the object network is selected as the candidate network only when the object network corresponds to the external network interface and the information on the object network is included in the subscribing information on the user equipment.

6. The method of claim 1, wherein (c) comprises:

(c1) determining whether or not the number of selected candidate networks is two or more;

(c2) when the determined number of the selected candidate networks is two or more, selecting a target network from among all of the candidate networks with reference to information on the all of the selected candidate networks and a decision basis of the target network set in the user equipment; and

(c3) when the number of the selected target networks determined in (c2) is two or more, deciding the only target network according to precedence of the decision basis.

7. The method of claim 6, wherein the decision basis is QoS (quality of service) of the candidate network and usage cost of the candidate network.

8. The method of claim 6, wherein in (c), when the number of the selected candidate network is one, the one candidate network is decided as the only target network.

17. A computer-readable medium having embodied thereon a computer program for the method of claim 8.

9. A method of selecting a handover target network, comprising:

(a) discovering handover object networks of a user equipment by a PoS (point of service) of a current network to which the user equipment which wants to execute a handover is currently connected;

(b) selecting handover candidate networks from among the discovered object networks by the PoS;

(c) deciding the only handover target network from among the selected candidate networks by the PoS; and

(d) executing the handover of the user equipment to the decided target network by the PoS.

10. The method of claim 9, wherein in (a), the PoS requests information on an object network of a network information server having the information on the object network, and the network information server transmits the information on the object network to the PoS in response to the request.

11. The method of claim 9, wherein (b) comprises:

(b1) perceiving information on the user equipment by the PoS;

(b2) determining whether the user equipment needs to be handed over by the PoS;

(b3) when the need is determined, determining handover intention of the user equipment;

(b4) when the user equipment has the handover intention, determining whether or not the information on the object network corresponds to the perceived information on the user equipment; and

(b5) when the correspondence is determined, the object network is designated as one of the candidate networks.

12. The method of claim 11, wherein in (b2), the PoS monitors in real time quality and signal strength of the current network and quality and signal strength of the object network, and determines that a handover is needed when the quality and the signal strength of the current network decrease to less than critical values, or the quality and the signal strength of the object network increase to more than critical values.

13. The method of claim 12,

wherein (b4) comprises:

(b41) determining whether or not the object network corresponds to an external network interface included in the user equipment; and

(b42) when the correspondence is determined in (b41), determining whether or not the information on the object network is included in subscribing information on the user equipment, and

wherein the object network is selected as the candidate network only when the object network corresponds to the external network interface and the information on the object network is included in the subscribing information on the user equipment.

14. The method of claim 9, wherein (c) comprises:

(c1) determining whether or not the number of the selected candidate networks is two or more by the PoS;

(c2) when the determined number of the selected candidate networks is two or more, selecting a target network from among all of the candidate networks with reference to information on the all of the selected candidate networks and a decision basis of the target network set in the user equipment; and

(c3) when the number of the selected target networks determined in (c2) is two or more, deciding the only target network according to precedence of the decision basis.

15. The method of claim 14, wherein the decision basis is QoS of the candidate network and usage cost of the candidate network.

16. The method of claim 14, wherein in (c), when the number of the selected candidate networks is one, the one candidate network is decided as the only target network.

18. A computer-readable medium having embodied thereon a computer program for the method of claim 16.

19. A system for selecting a handover target network, comprising:

an object network discovery unit discovering handover object networks of a user equipment which wants to execute a handover;

a candidate network selection unit selecting handover candidate networks from among the discovered object networks; and

a target network decision unit deciding the only handover target network from among the selected candidate networks.

20. The system of claim 19, further comprising a network information server having information on the object networks,

wherein the object network discovery unit requests the information on an object network of the network information server, and the network information server transmits the information on the object network to the object network discovery unit in response to the request in order to discover the candidate networks.

21. The system of claim 19, wherein the candidate network selection unit comprises:

a handover need determining unit determining a handover of the user equipment is needed;

an information correspondence determining unit determining whether or not the information on the object network corresponds to information included in the user equipment when the need is determined; and

a candidate network designation unit designating the object network as one of the candidate networks when the information on the object network corresponds to the information included in the user equipment.

22. The system of claim 21, wherein the need determining unit monitors in real time quality and signal strength of a current network to which the user equipment is currently connected and quality and signal strength of the object network, and determines that a handover of the user equipment is needed when the quality and the signal strength of the current network decrease to less than critical values, or the quality and the signal strength of the object network increase to more than critical values.

23. The system of claim 21,

wherein the information correspondence determining unit determines whether or not the object network corresponds to an external network interface included in the user equipment and the information on the object network is included in subscribing information on the user equipment, and

wherein the candidate network designation unit decides the object network as the candidate network only when the object network corresponds to the external network interface and the information on the object network is included in the subscribing information on the user equipment.

24. The system of claim 19, wherein the target network decision unit comprises:

a candidate network number determining unit determining whether or not the number of the selected candidate networks are plural;

a target network selection unit selects the target network from among all of the candidate networks with reference to information on the all of the selected candidate networks and a decision basis of the target network set in the user equipment when the number of the selected candidate networks are plural; and

a final decision unit deciding the only target network according to precedence of the decision basis when the number of the target networks selected by the target network selection unit is two or more.

25. The method of claim 24, wherein the decision basis is QoS of the candidate network and usage cost of the candidate network.

26. The method of claim 24, wherein the target network decision unit decides the one candidate network as the only target network when the number of the selected candidate network is one.