Handover with postponed path switch

1. An apparatus comprising:

at least one processor; and

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

determine, during a handover of a user equipment from a first access node to a second access node, that a path switch can be initiated;

determine at least one condition for initiating the path switch;

postpone the initiation of the path switch until the at least one condition has been met;

in response to determining that the at least one condition has been met, indicate the initiation of the path switch to the second access node; and

maintain a connection between the first access node and a mobility management entity or a connection between the first access node and a serving gateway at least until the at least one condition is met,

wherein the at least one condition comprises at least one of:

an empty buffer for the user equipment,

a congested interface between the first access node and the second access node,

a congested interface between one of the first or the second access node and one of a mobility management entity or a serving gateway,

an expiry of a path switch postponement timer set to a value dependent on one of channel measurements or channel frequency,

a processing limitation at the first access node, or

a condition requiring a handover from the second access node to a third access node, and

wherein the apparatus comprises the first access node.

2. The apparatus as in claim 1 , wherein a postponement timer of the path switch is equal to a predefined value depending on at least one of a channel measurement and a channel frequency.

3. The apparatus as in claim 1 , wherein the condition of empty buffer for the user equipment is met when data buffered for the user equipment at the first access node or at a serving gateway is depleted.

4. The apparatus as in claim 1 , wherein the condition of congested interface is met when the interface is determined to approach or reach a capacity limit of a defined value or is within a defined margin of the capacity limit.

5. The apparatus as in claim 1 , wherein said at least one memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to transmit or receive the at least condition from the first access node or the second access node.

6. The apparatus as in claim 1 , wherein the apparatus is or is comprised in one of:

the first access node and wherein said at least one memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to start a path switch postponement timer in response to receiving a handover preparation confirmation message;

the second access node and wherein said at least one memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to start a path switch postponement timer in response to sending a handover preparation confirmation message;

a mobility management entity and wherein said at least one memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to start a path switch postponement timer in response to receiving a path switch request message; or

a serving gateway and wherein said at least one memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to start a path switch postponement timer in response to receiving a modify bearer request message.

7. A method comprising:

determining, during a handover of a user equipment from a first access node to a second access node, that a path switch can be initiated;

determining at least one condition for initiating the path switch;

postponing the initiation of the path switch until the at least one condition has been met;

in response to determining that the at least one condition has been met, indicating the initiation of the path switch to the second access node; and

maintaining a connection between the first access node and a mobility management entity or a connection between the first access node and a serving gateway at least until the at least one condition is met,

wherein the at least one condition comprises at least one of:

an empty buffer for the user equipment,

a congested interface between the first access node and the second access node,

a congested interface between one of the first or the second access node and one of the mobility management entity or the serving gateway,

an expiry of a path switch postponement timer set to a value dependent on one of channel measurements or channel frequency,

a processing limitation at the first access node, or

a condition requiring a handover from the second access node to a third access node,

wherein the method is performed by a network node, the network node comprising the first access node.

8. The method as in of claim 7 , wherein a postponement timer of the path switch is equal to a predefined value depending on at least one of a channel measurement and a channel frequency.

9. The method as in claim 7 , wherein the condition of empty buffer for the user equipment is met when data buffered for the user equipment at the first access node or at the serving gateway is depleted.

10. The method as in claim 7 , wherein the condition of congested interface is met when the interface is determined to approach or reach a capacity limit of a defined value or is within a defined margin of the capacity limit.

11. The method as in claim 7 , further comprising transmitting or receiving the at least one condition from the first access node or the second access node.

12. The method as in claim 7 , wherein the network node being one of:

the first access node and further comprising starting a path switch postponement timer in response to receiving a handover preparation confirmation message;

the second access node and further comprising starting a path switch postponement timer in response to sending a handover preparation confirmation message;

a mobility management entity and further comprising starting a path switch postponement timer in response to receiving a path switch request message; or

a serving gateway and further comprising starting a path switch postponement timer in response to receiving a modify bearer request message.

13. A non-transitory computer readable medium tangibly encoded with a computer program executable by a processor to perform actions comprising:

determining, during a handover of a user equipment from a first access node to a second access node, that a path switch can be initiated;

determining at least one condition for initiating the path switch;

postponing the initiation of the path switch until the at least one condition has been met;

in response to determining that the at least one condition has been met, indicating the initiation of the path switch to the second access node; and

maintaining a connection between the first access node and a mobility management entity or a connection between the first access node and a serving gateway at least until the at least one condition is met,

wherein the at least one condition comprises at least one of:

an empty buffer for the user equipment,

a congested interface between the first access node and the second access node,

a congested interface between one of the first or the second access node and one of the mobility management entity or the serving gateway,

an expiry of a path switch postponement timer set to a value dependent on one of channel measurements or channel frequency,

a processing limitation at the first access node, or

a condition requiring a handover from the second access node to a third access node,

wherein the method is performed by a network node, the network node comprising the first access node.