Apparatus, method and computer program for UE cell selection control in non-terrestrial networks

1. An apparatus, comprising:

at least one processor; and

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

determining which of at least two lower layer radio units co-located at a first location, each lower layer radio unit associated with a higher layer radio unit, has a best path to the associated higher layer radio unit; and

dynamically adjusting a transmit power of the determined one of the at least two lower layer radio units received at a user equipment to be higher relative to a transmit power of any of the other of the at least two lower layer radio units received at the user equipment.

2. The apparatus according to claim 1 , wherein causing the transmit power of the determined one of the at least two lower layer radio units received at the user equipment to be higher relative to the transmit power of any of the other of the lower layer radio units received at the user equipment comprises increasing the transmit power of the determined distributed unit relative to the transmit power of any of the other of the lower layer radio units.

3. The apparatus according to claim 1 , wherein the causing the transmit power of the determined one of the at least two lower layer radio units received at the user equipment to be higher relative to the transmit power of any of the other of lower layer radio units received at the user equipment comprises providing an indication to the user equipment of an offset for the received transmit power.

4. The apparatus according to claim 3 , wherein the offset comprises a negative offset applicable to the transmit power received from any of the other of the at least two lower layer radio units.

5. The apparatus according to claim 3 , wherein the offset comprises a positive offset applicable to the received power from the determined one of the at least two lower layer radio units.

6. The apparatus according to claim 3 , wherein the at least one memory and computer program code are further configured, with the at least one processor, to cause the apparatus at least to perform:

providing the indication of the offset in a broadcast channel or dedicated signalling to the user equipment.

7. The apparatus according to claim 1 , wherein the at least two lower layer radio units are co-located on a satellite.

8. The apparatus according to claim 7 , wherein the relative increase in the transmit power is based on at least one of the satellite's trajectory and a trajectory of a second satellite having a further lower layer radio unit, wherein the further lower layer radio unit is a potential target serving radio unit for the user equipment and is connected to a current serving higher layer radio unit of the user equipment.

9. The apparatus according to claim 7 , wherein the determining is based on at least one of the satellite's trajectory and a trajectory of a second satellite having a further lower layer radio unit, wherein the further lower layer radio unit is a potential target serving radio unit for the user equipment and is connected to a current serving higher layer radio unit of the user equipment.

10. The apparatus according to claim 1 , wherein the relative increase in the transmit power is based on at least one of the location of the user equipment and the transmit power of a signal received at the at least two lower layer radio units from each of the higher layer radio units.

11. The apparatus according to claim 1 , wherein the determining is based on at least one of the location of the user equipment, the transmit power of a signal received at the at least two lower layer radio units from each of the higher layer radio units, a delay at the higher layer radio units and capacity of each of the higher layer radio units.

12. The apparatus according to claim 1 , wherein the best path is defined by handover performance.

13. The apparatus according to claim 1 , wherein each lower layer radio unit comprises a next generation NodeB distributed unit, gNB-DU and each higher layer radio unit comprises a next generation NodeB centralised unit, gNB-CU.

14. The apparatus according to claim 1 , wherein each of the higher layer radio units is located at a different location.

15. A method, comprising:

determining which of at least two lower layer radio units co-located at a first location, each lower layer radio unit associated with a higher layer radio unit, has a best path to the associated higher layer radio unit; and

dynamically adjusting a transmit power of the determined one of the at least two lower layer radio units received at a user equipment to be higher relative to a transmit power of any of the other of the at least two lower layer radio units received at the user equipment.

16. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following:

determining which of at least two lower layer radio units co-located at a first location, each lower layer radio unit associated with a higher layer radio unit, has a best path to the associated higher layer radio unit; and

dynamically adjusting a transmit power of the determined one of the at least two lower layer radio units received at a user equipment to be higher relative to a transmit power of any of the other of the at least two lower layer radio units received at the user equipment.