Restriction based handover

1. A method performed by a user equipment (UE), the UE being served by a serving network node, the method comprising:

determining whether a handover condition is satisfied, wherein the handover condition is a handover triggering condition; and

as a result of determining that the handover triggering condition is satisfied, triggering a handover of the UE from the serving network node to a target network node,

wherein

determining whether the handover condition is satisfied comprises:

i) determining that a power restriction exists for an uplink (UL) channel between the UE and the serving network node or ii) determining that a power restriction exists for an UL channel between the UE and the target network node;

obtaining a first performance indicator (PI) indicating an estimated performance of the UL channel between the UE and the serving network node;

obtaining a second PI indicating an estimated performance of an UL channel between the UE and the target network node; and

using the first PI, which indicates the estimated performance of the UL channel between the UE and the serving network node, and the second PI, which indicates the estimated performance of the UL channel between the UE and the target network node, to determine whether the handover condition is satisfied, further wherein

the method comprises the step of triggering the handover of the UE from the serving network node to a target network node as a result of determining that the handover triggering condition is satisfied,

the method further comprises obtaining a first downlink performance indicator (DPI) indicating a performance of a downlink (DL) channel between the UE and the target network node, and

the step of determining whether the handover triggering condition is satisfied comprises using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover triggering condition is satisfied, wherein

using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover condition is satisfied comprises: comparing PI_2 to PI_1 and comparing DPI_1 with a threshold value, wherein

comparing PI_2 to PI_1 comprises determining if PI_2 is greater than (PI_1+X), where X is a predetermined value, and

the handover triggering condition is determined to be satisfied when: PI_2 is determined to be greater than (PI_1+X), and DPI_1 is greater than the threshold value.

2. The method of claim 1 , wherein determining whether the handover condition is satisfied further comprises any one or combination of:

determining an amount of uplink (UL) data to be transmitted by the UE and comparing the determined amount to an UL data threshold,

determining an amount of downlink (DL) data to be received at the UE and comparing the determined amount to a DL data threshold, and

comparing the amount of UL data and the amount of DL data.

3. The method of claim 1 , wherein

the method further comprises obtaining a first estimated total gain (g1), wherein g1 is an estimated total gain of the UL channel between the UE and the serving network node,

the method further comprises obtaining a second estimated total gain (g2), wherein g2 is an estimated total gain of the UL channel between the UE and the target network node, obtaining the first PI (PI_1) comprises determining a first maximum allowable uplink transmit power and determining PI_1 based on the first maximum allowable uplink transmit power and g1, and

obtaining the second PI (PI_2) comprises determining a second maximum allowable uplink transmit power and determining PI_2 based on the second maximum allowable uplink transmit power and g2.

4. The method of claim 3 , wherein

the method further comprises, as a result of determining that a power restriction exists for the UL channel between the UE and the serving network node, setting a power reduction value to a value greater than zero; and

determining the first maximum allowable uplink transmit power comprises determining the first maximum allowable uplink transmit power using the power reduction value.

5. The method of claim 1 , the method further comprising:

as a result of determining that the handover triggering condition is satisfied, sending to the serving network node a message including information that triggers the serving network node to initiate the handover of the UE from the serving network node to the target network node.

6. The method of claim 1 , the method further comprising:

as a result of determining that the handover triggering condition is satisfied, (i) modifying a mobility measurement report that indicates an actual strength of a signal received at the UE, wherein the signal was sent from the serving network node or from the target network node and (ii) transmitting to the serving network node a message including the modified mobility measurement report.

7. The method of claim 6 , wherein the modified mobility measurement report indicates that:

in case the signal was sent from the serving network node, the UE received a signal of which strength is lower than the actual strength of the signal received at the UE, and

in case the signal was sent from the target network node, the UE received a signal of which strength is higher than the actual strength of the signal received at the UE.

8. The method of claim 1 , wherein

the UE comprises a first antenna arrangement and a second antenna arrangement, and

the method further comprises:

as a result of determining that the handover triggering condition is satisfied, turning off the first antenna arrangement;

after turning off the first antenna arrangement, generating a mobility management report; and

transmitting to the serving network node the generated mobility management report.

9. The method of claim 1 , the method further comprising:

as a result of determining that the handover inhibiting condition is satisfied, (i) modifying a mobility measurement report that indicates actual strength of a signal received at the UE, wherein the signal was sent from the serving network node or from the target network node and (ii) transmitting to the serving network node a message including the modified mobility measurement report.

10. The method of claim 9 , wherein the modified mobility measurement report indicates that:

in case the signal was sent from the serving network node, the UE received a signal of which strength is higher than the actual strength of the signal received at the UE, and

in case the signal was sent from the target network node, the UE received a signal of which strength is lower than the actual strength of the signal received at the UE.

11. The method of claim 1 , wherein determining that the power restriction exists comprises detecting the presence of a portion of a human body proximate to an antenna arrangement of the UE.

12. A user equipment (UE), the UE comprising:

processing circuitry; and

a memory, said memory containing instructions executable by said processing circuitry, whereby the UE is configured to perform a process comprising:

determining that a handover condition is satisfied, wherein the handover condition is a handover triggering condition or a handover inhibiting condition; and

as a result of determining that the handover triggering condition is satisfied, triggering a handover of the UE from a serving network node to a target network node, or

as a result of determining that the handover inhibiting condition is satisfied, inhibiting a handover of the UE from the serving network node to the target network node, wherein

determining whether the handover condition is satisfied comprises:

i) determining that a power restriction exists for an uplink (UL) channel between the UE and the serving network node or ii) determining that a power restriction exists for an UL channel between the UE and the target network node;

obtaining a first performance indicator (PI) indicating an estimated performance of the UL channel between the UE and the serving network node;

obtaining a second PI indicating an estimated performance of an UL channel between the UE and the target network node; and

using the first PI, which indicates the estimated performance of the UL channel between the UE and the serving network node, and the second PI, which indicates the estimated performance of the UL channel between the UE and the target network node, to determine whether the handover condition is satisfied, further wherein

the method comprises the step of triggering the handover of the UE from the serving network node to a target network node as a result of determining that the handover triggering condition is satisfied,

the method further comprises obtaining a first downlink performance indicator (DPI) indicating a performance of a downlink (DL) channel between the UE and the target network node, and

the step of determining whether the handover triggering condition is satisfied comprises using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover triggering condition is satisfied, wherein

using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover condition is satisfied comprises: comparing PI_2 to PI_1 and comparing DPI_1 with a threshold value, wherein

comparing PI_2 to PI_1 comprises determining if PI_2 is greater than (PI_1+X), where X is a predetermined value, and

the handover triggering condition is determined to be satisfied when: PI_2 is determined to be greater than (PI_1+X), and DPI_1 is greater than the threshold value.

13. A computer program product comprising a non-transitory computer readable medium storing a computer program, the computer program comprising computer program code which is able to, when run on processor circuitry of a user equipment (UE), cause the UE to perform a process comprising:

determining that a handover condition is satisfied, wherein the handover condition is a handover triggering condition or a handover inhibiting condition; and

as a result of determining that the handover triggering condition is satisfied, triggering a handover of the UE from a serving network node to a target network node, or

as a result of determining that the handover inhibiting condition is satisfied, inhibiting a handover of the UE from the serving network node to the target network node, wherein

determining whether the handover condition is satisfied comprises:

i) determining that a power restriction exists for an uplink (UL) channel between the UE and the serving network node or ii) determining that a power restriction exists for an UL channel between the UE and the target network node;

obtaining a first performance indicator (PI) indicating an estimated performance of the UL channel between the UE and the serving network node;

obtaining a second PI indicating an estimated performance of an UL channel between the UE and the target network node; and

using the first PI, which indicates the estimated performance of the UL channel between the UE and the serving network node, and the second PI, which indicates the estimated performance of the UL channel between the UE and the target network node, to determine whether the handover condition is satisfied, further wherein

the method comprises the step of triggering the handover of the UE from the serving network node to a target network node as a result of determining that the handover triggering condition is satisfied,

the method further comprises obtaining a first downlink performance indicator (DPI) indicating a performance of a downlink (DL) channel between the UE and the target network node, and

the step of determining whether the handover triggering condition is satisfied comprises using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover triggering condition is satisfied, wherein

using the first PI (PI_1), the second PI (PI_2), and the first DPI (DPI_1) to determine whether the handover condition is satisfied comprises: comparing PI_2 to PI_1 and comparing DPI_1 with a threshold value, wherein

comparing PI_2 to PI_1 comprises determining if PI_2 is greater than (PI_1+X), where X is a predetermined value, and

the handover triggering condition is determined to be satisfied when: PI_2 is determined to be greater than (PI_1+X), and DPI_1 is greater than the threshold value.