Method, apparatus and system for dual connectivity handover

1. A method comprising:

receiving, at a secondary cell, mapping information from a target primary cell;

using the mapping information to associate a connection request with a user equipment associated with the secondary cell,

wherein said mapping information comprises user equipment identity information;

wherein said user equipment identity information comprises a cell radio network temporary identifier and at least one of an E-UTRAN cell global identifier and a physical cell identity; and

wherein the connection request is part of a handover procedure of the user equipment to the target primary cell from a source primary cell; and

using the connection request associated with the user equipment to keep an ongoing session between the secondary cell and the user equipment.

2. A method according to claim 1 , comprising: receiving said mapping information in one of a secondary node addition request message and a secondary node modification request message.

3. A method according to claim 1 , comprising performing said method at a base station which controls the secondary cell.

4. A method comprising:

receiving, at a target primary cell and from a source primary cell, mapping information as part of a handover procedure of a user equipment from the source primary cell to the target primary cell; and

providing by said target cell said mapping information to a secondary cell for use in associating a connection request with a user equipment associated with the secondary cell in order for the secondary cell to keep an ongoing session between the secondary cell and the user equipment,

wherein said mapping information comprises user equipment identity information;

wherein said user equipment identity information comprises a cell radio network temporary identifier and at least one of an E-UTRAN cell global identifier and a physical cell identity; and

wherein the connection request is part of the handover procedure of the user equipment to the target primary cell from the source primary cell.

5. A method according to claim 4 , comprising providing application protocol identity to the secondary cell in dependence on a received control plane address.

6. A method according to claim 4 , comprising providing said mapping information in one of a secondary node addition request message and a secondary node modification request message.

7. A method comprising:

performing at a source primary cell a handover procedure to handover a user equipment from the source primary cell to a target primary cell, the handover procedure comprising:

providing, to the target primary cell, mapping information as part of the handover procedure,

wherein said mapping information comprises user equipment identity information for a user equipment associated with a secondary cell;

wherein said user equipment identity information comprises at least one of an E-UTRAN cell global identifier, a cell radio network temporary identifier, an application protocol identity, a physical cell identity and a control plane address; and

wherein the user equipment identity information is for use by the target primary cell for sending to a secondary cell to allow the secondary cell to map the equipment identity information with the user equipment associated with the secondary cell in order for the secondary cell to keep an ongoing session between the secondary cell and the user equipment.

8. An apparatus, said apparatus comprising:

at least one processor;

and at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

receive, at a secondary cell, mapping information from a target primary cell;

use the mapping information to associate a connection request with a user equipment associated with the secondary cell,

wherein said mapping information comprises user equipment identity information;

wherein said user equipment identity information comprises a cell radio network temporary identifier and at least one of an E-UTRAN cell global identifier and a physical cell identity; and

wherein the connection request is part of a handover procedure of the user equipment to the target primary cell from a source primary cell; and

using the connection request associated with the user equipment to keep an ongoing session between the secondary cell and the user equipment.

9. An apparatus, said apparatus comprising:

at least one processor; and at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

receive, at a target primary cell and from a source primary cell, mapping information as part of a handover procedure of a user equipment from the source primary cell to the target primary cell; and

provide by said target cell said mapping information to a secondary cell for use in associating a connection request with a user equipment associated with the secondary cell in order for the secondary cell to keep an ongoing session between the secondary cell and the user equipment,

wherein said mapping information comprises user equipment identity information;

wherein said user equipment identity information comprises the cell radio network temporary identifier and at least one of an E-UTRAN cell global identifier and a physical cell identity; and

wherein the connection request is part of the handover procedure of the user equipment to the target primary cell from the source primary cell.

10. An apparatus, said apparatus comprising:

at least one processor; and at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

performing at a source primary cell a handover procedure to handover a user equipment from the source primary cell to a target primary cell, the handover procedure comprising:

provide, to the target primary cell, mapping information as part of the handover procedure,

wherein said mapping information comprises user equipment identity information;

wherein said user equipment identity information comprises the cell radio network temporary identifier and at least one of an E-UTRAN cell global identifier and a physical cell identity; and

wherein the user equipment identity information is for use by the target primary cell for sending to a secondary cell to allow the secondary cell to map the equipment identity information with the user equipment associated with the secondary cell in order for the secondary cell to keep an ongoing session between the secondary cell and the user equipment.