Interview Questions on LTE
1. Why sub carrier spacing is more for wifi than lte
2. Which factor determines the carrier spacing in OFDM systems
3. Why is SC FDMA used in LTE uplink
4. What are PSS and SSS. Explain the need for this
5. What sequences are used for PSS and SSS
6. What are the parameters that are received decoded from PSS and SSS
7. How does a UE distinguish if Enb is configured for TDD or FDD
8. What are the parameters that can be decoded from PBCH
9. How is the System frame number decoded from PBCH even if LSB two bits are not present in MIB information
10. Explain the procedure for ATTACH in LTE UE
11. What is Downlink control Information (DCI)
12. DCI0 vs DCI1a
13. Explain the procedures that happen when a UE is powered on. (wrt physical layer)
14. Explain LTE Frame structure
15. What are the bandwidths used in LTE
16. What is carrier aggregation in LTE-Advanced
17. Explain EICIC and FEICIC features
18. what is SRS. Explain aperiodic and periodic SRS
19. Explain about radio link failure in LTE
20. Explain RACH procedure in LTE
21. What is the need for Timing Alignement commands from eNB. when does the timing alignment timer expire
22. Explain about MAC control element
23. What are TM1, TM2, TM3, TM4 modes
24. Explain all downlink physical channels
25. Explain all uplink physical channels
26. What is the difference betweeen Idle and Connected mode
27. What is a Resource block
28. What is discontinuous reception mode and why is it used. Explain connected DRX and idle DRX
29. What does Scheduling request mean and what is the need for transmitting this.
30. How does LTE UE positioning work
31. What are the number of subcarriers for each bandwidth in LTE
32. What are the types of handover in LTE
2. Which factor determines the carrier spacing in OFDM systems
3. Why is SC FDMA used in LTE uplink
4. What are PSS and SSS. Explain the need for this
5. What sequences are used for PSS and SSS
6. What are the parameters that are received decoded from PSS and SSS
7. How does a UE distinguish if Enb is configured for TDD or FDD
8. What are the parameters that can be decoded from PBCH
9. How is the System frame number decoded from PBCH even if LSB two bits are not present in MIB information
10. Explain the procedure for ATTACH in LTE UE
11. What is Downlink control Information (DCI)
12. DCI0 vs DCI1a
13. Explain the procedures that happen when a UE is powered on. (wrt physical layer)
14. Explain LTE Frame structure
15. What are the bandwidths used in LTE
16. What is carrier aggregation in LTE-Advanced
17. Explain EICIC and FEICIC features
18. what is SRS. Explain aperiodic and periodic SRS
19. Explain about radio link failure in LTE
20. Explain RACH procedure in LTE
21. What is the need for Timing Alignement commands from eNB. when does the timing alignment timer expire
22. Explain about MAC control element
23. What are TM1, TM2, TM3, TM4 modes
24. Explain all downlink physical channels
25. Explain all uplink physical channels
26. What is the difference betweeen Idle and Connected mode
27. What is a Resource block
28. What is discontinuous reception mode and why is it used. Explain connected DRX and idle DRX
29. What does Scheduling request mean and what is the need for transmitting this.
30. How does LTE UE positioning work
31. What are the number of subcarriers for each bandwidth in LTE
32. What are the types of handover in LTE
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ReplyDelete1. Why sub carrier spacing is more for wifi than lte
ReplyDeleteAnswer: I think LTE support high mobility support compare to WiFi, which means LTE technology support you service even when you are moving with very high speed of the order of around 300Km/h. as we know as the high the mobility of channel less will be the coherence time ( high doppler shift), due to which we have keep sub-carrier spacing small for LTE.
In LTE , cellular signal coverage is more, so more delay spread-> More ISI-> More freq selective fading due to less coherence BW. Coherence BW is inversely proportional to delay spread.
ReplyDeleteTo make channel freq flat channel, sub-carrier BW must be less than coherence BW
In wifi , delay spread is less due to less area coverage