LTE Intermediate Interview Question

Following are the some basic and advanced 20 Top LTE Intermediate Interview Question and answer for both beginner and experience LTE Tester.

Before going ahead, please have a look on LTE Testing to have some better understanding on the LTE basic. Let’s have a look on LTE Intermediate Interview Question

1. What is the RLC mode is used to send MIB and SIB?

Ans. TM Mode

2. What is the RLC mode used for paging message?

Ans. TM Mode

3. What is the difference between RLC PDU and RLC PDU segment?

Ans. The difference between RLC PDU and RLC PDU segment

  • RLC PDU : Segment or concatenate the SDU into RLC PDU,
    Add a RLC Header on top of the RLC PDU
  • RLC Segment : It will split the huge packets into multiple SDUs based on the information carried by RLC header.

4. Which RLC modes does only buffering Operation ?

Ans. TM Mode

5. Which RLC mode does only below operation? 

  1. Buffering
  2. Segmentation
  3. Concatenation
  4. Add RLC Header

Ans. UM / AM mode

6. Which RLC mode does the below operation? 

  1. Buffering
  2. Reordering
  3. Remove the RLC header
  4. Reassembly

Ans. AM mode

7. Which RLC mode does the flow control functionality?

Ans. AM Mode

8. What is error correction? Which RLC modes does error correction and how ?

Ans. Error correction is a mechanism to change the error bit back to normal bit. RLC AM mode does this error correction through ARQ mechanism.

9. What is the reason behind having GTP-U tunnel on X2-AP Interface?

Ans. During / After X2 handover, data transfer will be on GTP-U tunnel.

10. Name the UDP ports used for GTP-C and GTP-U?

  • GTP-C  UDP Port 2123
  • GTP-U UDP Port 2152

11. What is the significance of FI field?

Ans. The significance of FI field is Framing Info. This indicates whether a RLC SDU is segmented at the beginning and / or at the end of the data field.

12. What is the significance of D/C field?

Ans. This field indicates whether the PDU is for RLC control or data.

13. Which message is used by UE to request network for UL grant?

Ans. SR request (Scheduling Request)

14. Name any four message that will be sent on RLC TM mode?

Ans. MIB, SIB1,  RRC Connection request , RRC connection setup

15. List the logical channels which goes through TM RLC mode?


16. What is scheduling Request?

Ans. UE will request for UL grant to transmit the data

17. What is the buffer status report?

Ans. Buffer Status report will give the information on how much data is in UE buffer to be sent out.

18. What is Power Headroom report?

Ans. This is the difference between the nominal maximum Tx power and estimated UL-SCH Power.

19. List down the contents of Master Information block ?

  • Bandwidth
  • System frame number
  • PHICH configuration

20. Name the RRC message which is used by RRC  layer to setup the measurement configuration in the  UE ?

Ans. Measurement Report

21. Name the RRC message that will be exchanged when UE moves from RRC_IDLE to RRC_CONNCTED mode?

Ans. RRC Connection request, RRC Connection setup, RRC Connection setup complete

22. What is the use of UE using DRX in idle mode?

  • It will save the battery(Power) for UE in idle mode
  • DRX sleep mode reduce the power consumption

23. What are the SRB’s logical channel, RRC messages are being used by TM Mode?

Ans. SRB0, CCCH, RRC Connection Request, RRC Connection Setup

24. List any 4-establishment cause as part of RRC Connection Request?

Ans. MO signaling , MT Access, MO- data, Emergency

25. List any 3 important information that broadcast in SIB1?

Ans. PLMN-ID, Tracking Area code, Cell identity

Leave a Reply

Your email address will not be published. Required fields are marked *