Reporting beam failure

1. A terminal device comprising:

at least one processor; and

at least one memory including program codes;

the at least one memory and the program codes are configured to, with the at least one processor, cause the terminal device at least to:

detect a beam failure on one or more serving cells for the terminal device;

in response to detecting the beam failure on the one or more serving cells, obtain information concerning one or more candidate beams and the one or more serving cells, each of the one or more candidate beams associated with a respective one of the one or more serving cells;

transmit at least a portion of the information to a network device associated with the one or more serving cells; and

determine, based on an amount of the information, whether a resource allocated for transmitting the information is sufficient, and

in response to determining that the resource is sufficient, said transmitting at least a portion of the information to the network device associated with the one or more serving cells comprises transmitting, to the network device associated with the one or more serving cells, a full beam failure recovery (BFR) report in a medium access control (MAC) control element (CE), which contains all the information, and

in response to determining that the resource is insufficient, said transmitting at least a portion of the information to the network device associated with the one or more serving cells comprises transmitting, to the network device associated with the one or more serving cells, a truncated beam failure recovery (BFR) report in a medium access control (MAC) control element (CE), which contains only a portion of the information,

wherein the information comprises a first bitmap including a plurality of bits corresponding to a plurality of serving cells for the terminal device, and wherein a bit of the plurality of bits corresponding to a respective serving cell of the one or more serving cells is assigned with a predetermined value, and

wherein the information comprises a second bitmap including a plurality of bits corresponding to a plurality of serving cells for the terminal device, and wherein a bit of the plurality of bits is assigned with a predetermined value if the corresponding serving cell satisfies the following:

that a candidate beam for the corresponding serving cell has a quality above a threshold; and

that an indication of the candidate beam for the corresponding serving cell is included in the transmitted portion.

2. The terminal device of claim 1 , wherein the terminal device is caused to transmit the truncated BFR report after determining that a resource allocated for transmitting the information in full is insufficient.

3. The terminal device of claim 2 , wherein a full BFR MAC CE is otherwise transmitted which contains the information in full.

4. The terminal device of claim 1 , wherein the terminal device is further caused to

select at least one candidate beam of the one or more candidate beams; and

include an indication of the selected at least one candidate beam in the portion of the information.

5. The terminal device of claim 4 , wherein the at least one candidate beam is associated with a secondary cell of the one or more serving cells, wherein the one or more serving cells are indicated by one or more indices, and the at least one candidate beam is selected based at least on one of the following criteria:

a signal quality of a first candidate beam exceeds a threshold quality,

the secondary cell has the lowest index of the indices of the one or more serving cells,

the secondary cell has the highest index of the indices of the one or more serving cells,

the secondary cell belongs to a same group with a primary cell for the terminal device,

the secondary cell is associated with a plurality of further secondary cells,

the secondary cell is configured with intra-band carriers, or

a transmission has been scheduled on the secondary cell.

6. The terminal device of claim 1 , wherein the one or more serving cells include a serving cell, and wherein the terminal device is caused to obtain the information by:

determining signal qualities of a plurality of candidate reference signals configured for the serving cell;

detecting from the plurality of candidate reference signals a candidate reference signal having a signal quality above a threshold quality; and

generating an indication of the detected candidate reference signal as at least part of information concerning the one or more candidate beams.

7. The terminal device of claim 6 , wherein the terminal device is further caused to:

generate an indication of a candidate reference signal, which is identified from the plurality of candidate reference signals, as having the highest signal quality of the signal qualities of the plurality of candidate reference signals, and wherein the indication is included in information concerning the one or more candidate beams.

8. The terminal device of claim 1 , wherein the terminal device is further caused to:

transmit an indication that the information is partially transmitted.

9. The terminal device of claim 1 , wherein the terminal device is further caused to:

transmit a remaining portion of the information to the network device.

10. The terminal device of claim 1 , wherein the portion of the information includes information concerning at least one of the one or more candidate beams, which is selected based on a priority order of the one or more candidate beams.

11. The terminal device of claim 10 , wherein the priority order is based on an ascending order of indices of the one or more serving cells.

12. A network device, comprising:

at least one processor; and

at least one memory including program codes;

the at least one memory and the program codes are configured to, with the at least one processor, cause the network device at least to:

receive, from a terminal device, a truncated beam failure recovery (BFR) report in a medium access control (MAC) control element (CE), which contains only a portion of information, wherein the information concerns one or more candidate beams and one or more serving cells on which a beam failure is detected, each of the one or more candidate beams associated with a respective one of the one or more serving cells, or

receive, from the terminal device, a full beam failure recovery (BFR) report in a medium access control (MAC) control element (CE), which contains all the information; and

determine, based on the portion of the information, that at least one beam failure is reported for the one or more serving cells,

wherein the information comprises a first bitmap including a plurality of bits corresponding to a plurality of serving cells for the terminal device, and wherein a bit of the plurality of bits corresponding to a respective serving cell of the one or more serving cells is assigned with a predetermined value, and

wherein the information comprises a second bitmap including a plurality of bits corresponding to a plurality of serving cells for the terminal device, and wherein a bit of the plurality of bits is assigned with a predetermined value if the corresponding serving cell satisfies the following:

that a candidate beam for the corresponding serving cell has a quality above a threshold; and

that an indication of the candidate beam for the corresponding serving cell is included in the portion of the information.

13. The network device of claim 12 , wherein the network device is caused to receive the truncated BFR report in an instance in which a resource allocated for transmitting the information in full is insufficient.

14. The network device of claim 13 , wherein a full BFR MAC CE is otherwise received which contains the information in full.

15. The network device of claim 12 , wherein the portion of the information comprises an indication of at least one candidate beam of the one or more candidate beams, and the network device is further caused to:

determine, from the one or more serving cells, at least one serving cell associated with the at least one candidate beam.

16. The network device of claim 15 , wherein a first candidate beam of the at least one candidate beam is associated with a secondary cell of the one or more serving cells, wherein the one or more serving cells are indicated by one or more indices, and the network device is configured to determine the secondary cell as one of the at least one serving cell if:

the secondary cell has the lowest index of the indices of the one or more serving cells,

the secondary cell has the highest index of the indices of the one or more serving cells,

the secondary cell belongs to a same group with a primary cell for the terminal device,

the secondary cell is associated with a plurality of further secondary cells,

the secondary cell is configured with intra-band carriers, or

a transmission has been scheduled on the secondary cell.

17. The network device of claim 12 , wherein the network device is further caused to:

receive an indication that the information is partially transmitted.

18. The network device of claim 12 , wherein the network device is further caused to:

receive a remaining portion of the information from the terminal device.

19. The network device of claim 12 , wherein the portion of the information includes information concerning at least one of the one or more candidate beams which is selected based on a priority order of the one or more candidate beams.

20. The network device of claim 19 , wherein the priority order is based on an ascending order of indices of the serving cells.