Beam indication

1. An apparatus, comprising:

at least one processor;

at least one memory including computer program code; and

at least one interface configured for communication with at least another apparatus,

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

storing at least one beam determination entry, wherein each of said at least one beam determination entry is indicative of a respective first beam and at least one respective second beam narrower than said first beam and at least partially in quasi co-location with said first beam,

receiving indicator information indicative of one of said at least one beam determination entry, and

selecting, for a predetermined physical channel, a transmission beam out of said first beam and said at least one second beam of said indicated one of said at least one beam determination entry based on receiving power measurement results in relation to said first beam and said at least one second beam of said indicated one of said at least one beam determination entry, wherein

said first beam of said indicated one of said at least one beam determination entry is set as a default beam of said indicated one of said at least one beam determination entry,

said at least one second beam of said indicated one of said at least one beam determination entry is selected as said transmission beam, and wherein

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

receiving a non-acknowledgement message, wherein

said non-acknowledgement message is a hybrid automatic repeat request non-acknowledgement message, and

selecting said default beam based on said non-acknowledgement message as said transmission beam.

2. The apparatus according to claim 1 , wherein

each of said at least one beam determination entry includes a respective identifier, and

said indicator information corresponds to said identifier of said indicated one of said at least one beam determination entry.

3. The apparatus according to claim 1 , wherein

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

receiving said at least one beam determination entry.

4. The apparatus according to claim 1 , wherein

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

measuring a receiving power in relation to said first beam and said at least one second beam of said indicated one of said at least one beam determination entry.

5. The apparatus according to claim 1 , wherein

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

transmitting traffic of said predetermined physical channel utilizing said selected transmission beam.

6. The apparatus according to claim 1 , wherein

each of said first beam and said at least one second beam of said indicated one of said at least one beam determination entry is represented by a respective reference signal.

7. The apparatus according to claim 1 , wherein

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

deriving a spatial transmission filter for said predetermined physical channel based on said selected transmission beam.

8. The apparatus according to claim 1 , wherein

said selecting is based on receiving power measurement results in relation to said first beam, said at least one second beam, and a joint beam of said first beam and said at least one second beam.

9. The apparatus according to claim 1 , wherein

a beam corresponding to a highest receiving power measurement result is selected.

10. The apparatus according to claim 1 , wherein

said at least one second beam is selected if the receiving power measurement result in relation to said at least one second beam is higher than a predetermined threshold.

11. The apparatus according to claim 1 , wherein

said at least one second beam is selected if the receiving power measurement result in relation to said at least one second beam is higher than the receiving power measurement result in relation to said first beam by at least a predetermined amount.

12. The apparatus according to claim 1 , wherein

said at least one beam determination entry is configured in a beam indication table, or

said first beam is a synchronization signal block beam, or

said at least one second beam is a channel state information reference signal beam, or

said predetermined physical channel is one of a physical uplink control channel and a physical uplink shared channel, or

said at least one second beam at least partially in quasi co-location with said first beam is within a transmit aperture of said first beam, or

said receiving power measurement result in relation to a specific beam is an L1 reference signal received power in relation to a reference signal representing said specific beam, or

the apparatus is operable as or at a terminal, user equipment, mobile station or modem.

13. A method, comprising:

storing at least one beam determination entry, wherein each of said at least one beam determination entry is indicative of a respective first beam and at least one respective second beam narrower than said first beam and at least partially in quasi co-location with said first beam;

receiving indicator information indicative of one of said at least one beam determination entry; and

selecting, for a predetermined physical channel, a transmission beam out of said first beam and said at least one second beam of said indicated one of said at least one beam determination entry based on receiving power measurement results in relation to said first beam and said at least one second beam of said indicated one of said at least one beam determination entry, wherein

said first beam of said indicated one of said at least one beam determination entry is set as a default beam of said indicated one of said at least one beam determination entry, and

said at least one second beam of said indicated one of said at least one beam determination entry is selected as said transmission beam, and wherein the method further comprises

receiving a non-acknowledgement message, wherein

said non-acknowledgement message is a hybrid automatic repeat request non-acknowledgement message, and

selecting said default beam based on said non-acknowledgement message as said transmission beam.