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- What is the DRX and DRX active period? What channels does it monitor inactive period?
- What is MAC-ContentionResolutionTimer – What is the start and end activity?
- What is the HARQ RTT Timer?
- What is the msg3 buffer?
- What is the PRACH Resource Index?
- What is ra-PRACH-MaskIndex?
- What are the Logical Channels carried through HARQ?
- What are the Logical Channels NOT carried through HARQ?
- What are the Physical Channels Terminate at MAC/Physical boundary and are irrelevant to the upper layers?
- What are the Logical channels through which PBCH is carried through?
- What are the Logical Channels Carried by UL-SCH and DL-SCH?
- What Logical channels are carried by PDCCH and PUCCH Physical Channels?
- Which entities and situations and when do they initiate MAC RA Procedure? List them.
- When is your Temporary C-RNTI gets converted to C-RNTI? How many bits is it?
- How many RA Preambles are there? Why some of them are reserved by eNB?
- What is RA-Preamble-Group A and B? What is the difference?
- While UE trying RA, if paging & Reserved-preamble comes from eNB, will UE abandon the current RA and restart?
- RA-RNTI = 1+t_id+10*f_id. Explain what is t_id and f_id and their possible value range?
- What are the types of RAR?
- How do you know how many RAPIDs are there and the length of the RAR?
- What is Backoff indicator? What is the UE action on receiving this?
- What is the RAR window?
- If UE receives the RAR but not contention resolution message, within what time/mechanism it will retransmit?
- What are the parameters/info you get from eNB in the RAR?
- What is the relationship between HARQ Entity and HARQ Process? What is the maximum entity and processes allowed in each UE?
- Why there is a dedicated MAC process for BCH?
- What is the maximum time a UE will back off, before retransmitting the RA?
- What is TTI bundling? How many TTI’s can be bundled together?
- In Logical Channel Prioritization, what are PBR and BSD?
- How much is Bj incremented each TTI and what is its maximum value in MAC?
- Rewrite the channels/data in the priority order which MAC considers – CCCH, any other LoCH, BSR, PHR, BSR with padding.
- What channels are normally carried by TM, UM and AM RLC? List them for each.
- Are all MAC, RLC and PDCP PDU/SDU’s byte aligned?
- What is HARQ? Explain briefly?
- Any reason why RLC is recommended to do ARQ and not HARQ?
- What is polling bit? How is it managed?
- What is Poll_SN? How does it help?
- What is the sliding window? What is outside and inside the window?
- What is receiving window? What are the two edge variables describing the ends of the window for AM?
- What is the re-assembly units work? What variable does it maintain and moves for AM?
- What is Frame Indicator? What are the possible indicators?
- What is Re-segmentation Flag RF?
- What do you send in STATUS_PDU?
- What is LSF Field indicate?
- What are SO_start and SO_end?
- What is t_Status_Prohibit?
- What are Poll_PDU and Poll_Byte?
- For a voice call, Minimum how many MAC, RLC, and PDCP entities and Processes will you design both directions taken together? Specify the purpose of each.
- What is ROHC?
- What is Cyphering?
- How are Cyphering Keys generated?
- What is Integrity Protection?
- What are the keys for Integrity and how are they generated?
- What kind of ARQ or HARQ is implemented in PDCP?
- What is the maximum size of PDCP SDU recommended?
- What is COUNT and what is it used for?
- What are DRB and SRB? What is special about SRB0?
- What is FMS (First Missing SN) and Bitmap for STATUS PDU?
- What is MAC-I? How does it help?
- What are the various PDCP SN sizes possible?
