Basic Procedures

Question 1

What are the functions of SSS?

Answer 1

frame timing sync, determine cell ID group TODO

Question 2

structure of PSS

Answer 2

length 63 Zc sequences

Question 3

structure of SSS

Answer 3

TODO

Question 4

where are MIBs transmitted

Answer 4

BCCH - BCH - PBCH

Question 5

where are SIB transmitted

Answer 5

BCCH - DLSCH - PDSCH

Question 6

how does UE know SIB is coming

Answer 6

TODO - PDCCH is marked ith si rnti

Question 7

how many different SIBs are defined?

Answer 7

13

Question 8

what are the functions of PCRF

Answer 8

provided policy control and flow based charging control

Question 9

what are the contents of the paging message

Answer 9

list of UEs being paged, system information modification falg, ETWS flag

Question 10

different scenarios causing radio link failure

Answer 10

DL BLER > 10%, RACH problems, Failure after RLC retransmission, handover failure.

Question 11

contents of SIB 1

Answer 11

whether a UE is allowed to camp on a cell, UL?DL frame config in case of TDD, scheduling info from SIB 2 and beyond, TA code.

Question 12

functions of paging procedure

Answer 12

mobile terminated PS call, modile terminated CS fallback call, trigger UE to reacquire the system, provide earthquake and tsunami warning.

Question 13

functions of PSS

Answer 13

TODO

Question 14

information contained in MIBs

Answer 14

8 MSB of SFN, PHICH info, DL cell BW

Question 15

frequency of MIBs

Answer 15

40 ms

Question 16

frequency of SIB1

Answer 16

80 ms

Question 17

frequency of SIbs other than sib 1

Answer 17

80 to 5120 ms as SI messages

Question 18

different types of DL reference signals

Answer 18

cell specific reference signals, demodulation reference signal or UE specific reference signal, CSI reference signal

Question 19

location of the demodulation reference signal in the DL

Answer 19

transmitted in the resource block assigned to the UE

Question 20

structure of DM RS

Answer 20

12 reference symbol within a resource block pair

Question 21

uplink reference signals

Answer 21

Demodulation reference signal, sounding reference signal.

Question 22

function of DMRS on the uplink

Answer 22

channel estimation for demodulation of PUSCH and PUCCH

Question 23

function of SRS on the uplink

Answer 23

uplink channel dependent scheduling and link adaptation. Sometimes used for upink timing alignment.

Question 24

what is a MAC CE

Answer 24

a special structure carrying control information as parts of MAC header.

Question 25

LTE resource element

Answer 25

one OFDM sub carrier over one OFDM su=ymbol

Question 26

LTE resource block

Answer 26

70 OFDM symbols, 12 sub carriers

Question 27

B.W of a subcarrier

Answer 27

15 Khz

Question 28

BW of a resource block

Answer 28

15 X 12 = 180 Khz

Question 29

minmimum unit of scheduling

Answer 29

resource block

Question 30

how will the UE know if a system is FDD or TDD?

Answer 30

PSS and SSS are in diffrent locations

Question 31

what is the EPS bearer consists of

Answer 31

Radio Bearer (SRB and DRB) + S1 bearer + s5 bearer

Question 32

structure of cell specific reference signal

Answer 32

504 sequences defined - one corresponding to each cell

Question 33

functions of cell specific reference signal

Answer 33

channel estimation for demodulation of downlink physical channel, acquire channel state information, used in cell selection and handover

Question 34

location of cell specific reference signal

Answer 34

first and third last OFDM symbol of each time slot with a frequency domain spacing of 6 sub carriers.

Question 35

function of DMRS or UE specific reference signal

Answer 35

channel estimation of PDSCH where cell specific referebce signals are not to be used

Question 36

what is idle mode DRX?

Answer 36

indicates the number of radio frames in a paging cycle

Question 37

what is the call flow during the RACH process

Answer 37

``` from UE to eNB random access preamble random access response RRC connetion request contention resolution message ```

Question 38

what are two sets of messages exchanged when a UE de-registers.

Answer 38

detach request and response | delete session request and response

Question 39

between what two entities are te detach request and response exchanged?

Answer 39

UE and MME

Question 40

between what two entities are delete session requests and response exchanged

Answer 40

MME and SGW

Question 41

what is the trigger for network initiated EPS bearer setup?

Answer 41

starting an IMS call, i.e. a SIP invite from the Ue

Question 42

what are diffreent ways of indicating a timing dvances ti the UE

Answer 42

timing advance command in MAC RAR | timing advance command in MAC CE

Question 43

what is the vaidity of th uplink timing aligmnet as indicated by the enb

Answer 43

eNB provides UE with a configurable timing alignmenttimet

Question 44

what actvities are performed at the UE after expiry of timing alignment timer

Answer 44

UE re-initiates a RACH

Question 45

what are different phases of the cell search procedure?

Answer 45

acquisition of frequency and symbol synchrinization acquisition of downlink frame timing determination of physical layer identity of the cell

Question 46

what is BLER?

Answer 46

ratio of number of transport blocks with CRC failure/ total number of TBs recieved

Question 47

what is timing advance?

Answer 47

offset between the start of a recieved downlink subframe and the start of the corresponding uplink subframe.

Question 48

how long does the UE remain in short DRX?

Answer 48

untill the DRX short timer expiers

Question 49

what is the long DRX cycle?

Answer 49

The DRX cycle UE enters after the short timer

Question 50

what is idle mode DRX?

Answer 50

The UE monitors the PDCCH for paging indication only at certain times called paging occassions and sleeps rest of the time.

Question 51

what is the requirement of the cyclic prefix

Answer 51

copying the trailing part of the sybol prior to the start of the symbol to minimize the effect of delay spead.

Question 52

functions of the RLC layer

Answer 52

provides different data transmission modes supports ARQ procedure for ACKed mode concatenation, segmentation and reassembly for UM and AM mode.

Question 53

functions of PDCP layer

Answer 53

header compression, ciphering and deciphering

Question 54

purpose of RRC reconfiguration.

Answer 54

to establish or modify radio bearers, perform handover, support CA by adding and modyfying scells, transfer dedicated NAS information.

Question 55

purpose of RRC connection re-establishment

Answer 55

radio link failure,

Question 56

purpose of MAC control element

Answer 56

random access procedure, maintainence of uplink timing alignment, support semi persistent scheduling, activation and deactivation of scells.