LTE UE Power on Interview Questions Answers 11-20

LTE UE Power on Interview Questions Answers

Q11. What is the location of PSS in Type-2 Frame structure?

Ans. PSS also present twice in Radio Frame in Type-2 (TDD) frame structure.

• Sub Frame=1, ts=3, 2^nd ofdm symbol, middle 62 subcarrier.
• And Sub Frame=6, ts=12, 2^nd ofdm symbol

Q12. What is SSS, which sequence is using in SSS?

Ans. SSS stands for Secondary Synchronization Signal.

• SSS have special modified symbols but not follow zadoff-chu sequence. it has 2 formula 1st formula used for odd criteria and 2nd is used for even criteria. The output of formula contains 1 and -1, here 1=>1+0j and -1=>-1+0j. so there is no imaginary Axis. so graph is below:
  
  only 2 angle (0' and 180').
  
  Note** we don't use these angle for another symbols.

Q13. What kind of information SSS Carry?

Ans. It provide cell group id total 168 start from [0-167]

Q14. What is the location of SSS in Type-1 Frame structure?

Ans. SSS present twice in every Radio frame of Type-1 (fdd) frame structure.

• Middle 62 sub-carriers (out of total 72 sub-carriers), top 5 and bottom 5 sub-carriers are null of same ofdm symbol where SSS present.
• Sub-frame no.0 and 5.
• time slot (ts) 0 and 10^th.
• And second last OFDM symbol either Normal Cyclic or Extended Cyclic prefix.

Q15. What is the location of SSS in Type-2 Frame structure?

Ans. SSS also present twice in Radio Frame in Type-2 (TDD) frame structure.

• Sub Frame=0, ts=1, last ofdm symbol, middle 62 subcarrier.
• And Sub Frame=5, ts=11, last ofdm symbol

Q16. How UE calculate PCI?

Ans. PCI = 3 * N_cellgroupid + N_sectorid

• PCI = 3 * SSS + PSS
• PCI = 3 * 167 + 3
• Total [504] PCI are available in LTE.

Q17. After Calculate PCI how UE validate PCI, is it correct or not?

Ans. UE read Reference Signal for PCI validation and chennel estimation.

Q18. What is the role of System Informations in Power on procedure?

Ans. System Information (SI) carry MIB and SIB1 to SIB12 information. And these SI gathers lots of parameters info which is usefull to UE.

Q19. What is the difference between MIB and SIB in LTE?

Ans. MIB is 24 bit length system information block called Master Information Block carry:

• 3-bit Bandwidth information
• 3-bit Phich information
• 8-bit SFN (system frame number)info.
• 10-bit Reserved
• And periodicity of 40ms in LTE.

SIB carry

• Cell Access,
• Cell-reselection,
• Frequency band indicator,
• SIB2-to-SIB12 scheduling information and much more.
• SIB1 periodicity in LTE is 80ms and present in subframe no. 5

Q20. What is P-compensation in cell selection procedure?

Ans. P-compensation is a maximum UE transmit power level may use for cell Rach(read system information) minus maximum RF output power of UE in dBm

Pcompensation

max(UE_TXPWR_MAX_RACH-P_MAX,0)(dB)