LTE UE Power on Interview Questions Answers
Q01. In power on which Layer activate first?
Ans. The NAS layer activate 1st when
our mobile is switch on (power on).
Q02. What is the 1st job
RRC Layer performed during power on procedure?
Ans. When, our UE is
switch on, our UE NAS layer trigger a message to RRC layer to provide all the
plmn list present in a geographical area. After that RRC Layer start scanning
of all plmn’s and make a list and send it back to NAS layer.
Q03. How Physical
Layer Scan all Frequencies and pick-up 1 frequency?
Ans. When NAS layer
select a plmn (available in plmn list), then it trigger a message towards RRC
layer, RRC layer forward this message to Physical layer (via L1 Command) to searching best cell
behalf of cell access and cell selection parameters available in SIB1.
Q04. How UE select a
Frequency?
Ans. Once UE physical
layer select a cell frequency behalf of priority (set by operators), after that
UE will tries to guess middle frequency called as DC_frequency.
Q05. What is cell
selection and re-selection procedure in lte?
Ans. When our UE is
switch off it stored previous cell information eg: previous cell frequency,
bandwidth info and TAC like that. So when UE is switch on it will tries with
previous info based cell selection. But if it’s not present then it will find
new cell which information's are present in SIB1.
The Cell re-selection
is based on parameters deviation so our UE try to find a next strong cell. so
the formula is to do cell re-selection is
Srxlev>0 and
Squal>0
where
Srxlev=Qrxlevmeas-(Qrxlevmin+Qrxlevminoffset)-pcompensation
Squal=Qqualmeas-(Qqualmin+Qqualoffset).
Q06. How UE guess
middle DC frequency of a Bandwidth?
Ans. When UE pick a
frequecy according priority it tries to guess bandwidth middle DC-frequecy. It
happen in middle frequency the power value become 0db. So our UE know that this
is middle part of bandwidth then applied Zadoff-chu angular varience formula.
Q07. How NAS layer
select PLMN if no.’s of PLMN information provided by RRC Layer?
Ans. When RRC layer
provide PLMN list to NAS layer, UE NAS layer applied security level parameters
to, every PLMN present in a list. These security information present in USIM so
that a USIM belongs to particular operators, it will select only that operator
network without any fail.
Q08. What is PSS,
which sequence is using in PSS?
Ans. PSS stands for
Primary Synchronization Signal.
PSS is a specialized occupied symbol in frame Structure and generated by
Zadoff-chu Angular Varience.
Q09. What kind of information
PSS Carry?
Ans. It provide Sector
id of a cell eg: 0,1, 2.
Q10. What is the
location of PSS in Type-1 Frame structure?
Ans. PSS present in
every Radio frame and Sub-frame no. 0 and 5 on 1st time slot
(ts).
And last OFDM symbol
either Normal Cyclic or Extended Cyclic prefix.