Carrier Aggregation Interview Question Answer 16-25

Q16. How many Carrier allocation Schemes are available in CA?

Ans.

Q17. What is Intra-Band Contiguous?

Ans. Intra-band Contiguous CA it means component carrier belong to band X and all component carriers are contiguous
for example CA_X
* Denote intra-band Contiguous CA
CA_5, CA_1, CA_7 etc.

Q18. What is Intra-Band non-contiguous?

Ans. Intra-band non-contiguous CA it means component carrier belong to be band X but they have gap between them
for example CA_X_X
* Denote intra-band non-contiguous CA
CA_25_25, CA_5_5 etc.

Q19. What is Inter-Band non-contiguous?

Ans. Inter-band non-contiguous CA it means component carrier belong to X and Y.
For example CA_X_Y
* Denote inter-band non-contiguous CA
CA_5_8, CA_5_25 etc.

Q20. How to denoting band combinations?

Ans. CA_5, CA_5_5, CA_5_8 are examples to denoting band combinations in CA.

Q21. What is Cross Carrier scheduling?

Ans. DCI format is tranmitted on PDCCH channel in downlink and then downlink data is tranmitted on PDSCH channel. DCI format has information that is used by UE to decode the data present on PDSCH also DCI format have scheduling grant information that is used by ue to send data in uplink. Same DCI format transmitted by Secondary Cell also.
Cross Scheduling is enable the, DCI format of secondary cell also transmitted by primary cell pdcch. So it has some mechanism to tell you that for which cell a particular DCI format is intended for this purpose, a CIF field present in DCI format.

Q22. Advantage of cross carrier scheduling?

Ans. Advantage: as we know PDCCH is transmitted with higher power compared to PDSCH if UE receive data from multiple secondary cell then there could be an inter-cell interference on PDCCH. So the Cross carrier scheduling is an excellent way of removing inter-cell interference on PDSCH.

Q23. What is Carrier Indicator Field?

Ans. CIF means Carrier Indicator Field that tell for which cell or carrier this DCI format is intended.
Note: Cross carrier scheduling is an optional feature for UE.

Q24. What is the role of Physical Layer in CA?

Ans. 2 new PUCCH Formats were defined:
Format 1b (HARQ ACK/NACK for up-to 2 component carriers)
Format 3 (HARQ ACK/NACK for up-to 5 component carriers)
physical-layer-processing chain is repeated for every UL serving cell.

Q25. What is the role of MAC Layer in CA?

Ans. When a Secondary cell is added to UE it’s MAC entity play a role in secondary cell these are:

• 1 HARQ entity for that secondary cell to handle scheduling and other functionalities.
• BSR is used by the UE to provide the information about the amount of data is available for transmission in it’s uplink buffers.
• PHR is used by UE to tell the difference between current transmission power level and maximum possible transmission power level.
• Activate and deactivates secondary serving cells
• Maintains the timer “sCellDeactivationTimer”

            - used to monitor data inactivity

• Aggregates data from multiple cells