Interview question for 2g,3g,4g

Interview question of GSM
1) Which channel is used to transmit random access signals?
BCCH
CCCH Correct!
SDCCH
TCH
2) Which one of the following is the combination of main BCCH?
TCH+SACCH
FCH+SCH+BCH+CCCH Correct!
SDCCH/8+SACCH/8
FCH+SCH+BCH+SDCCH+SACCH
3) The Value Range of Timing Advance (TA) in GSM is?
0-31
0-127
0-63 Correct!
0-7
4) How many MS can be paged with 1 paging massage with IMSI?
1
2 Correct!
3
4
5) Directed Retry handover means?
TCH to TCH
SDCCH to TCH Correct!
SDCCH to SDCCH
None of Above
6) How many neighbors are measured by MS at a time?
5
6 Correct!
7
8
7) Time Duration of Super Frame?
3 Hour 28 minutes 53 seconds 760 ms
6.12 seconds Correct!
235.65 ms
120 ms
8) Maximum number of characters allowed in one SMS?
160 Correct!
170
180
150
9) If you have 5 MHz frequency band what will be the maximum number of
channels as per
GSM system?
25 Correct!
35
20
24

10) Which kind of Handovers more desired in the Network?
Rx Level
Power Budget Correct!
Rx Quality
Interference
11) SDCCH holding time for Normal location update is
3.8ms
3.5sec Correct!
3.5ms
None of them
12) SDCCH holding time for call setup (MOC) is
2.7sec Correct!
3.5sec
2.7ms
3.5ms
13) Same BCCH-BSIC combination in adjacency will lead
Will not cause any problem.
Massive Handove failaur
Call drop
B & C Correct!
14) What is the reason of ping-pong handover
Cable swap
No dominant cell coverage
Improper handover margine
All of above Correct!
15) If there is interference on the BCCH TRx and the call is going on at the
hopping Trx
Call will drop
Call will be unafected Correct!
Call will attempt handover due to this interference
None of above
16) If in a cell all KPI is going well but its TCH drop is high, there is no any RF
and hardware
issue then this TCH drop will be due to
Transcoder fail Correct!
Lapd fail
A & B
None of them
17) Which system informations are used in idle mode
System information 1,2,3,4,7 & 8 Correct!
System information 1,2,3,4,5,6,7 & 8
System information 1,2,3,4,5,6,9 & 10
System information 1,2,3,4,5,6,7,8,9,10,11,12 & 13
18) Which system informations are used for BA list
System information 1,2,3 & 4 Correct!
System information 5,6,8,9,10 & 12
System information 12 & 13
None of them
19) Which system informations are used for MA list

System information 13,10,9 & 4
System information 5 & 6 Correct!
None of them
20) Which system informations are used for GPRS
System information 12 & 13 Correct!
None of them
LTE DRIVE TEST PARAMETERS
RSRP :- Reference signal receive power.
• RSRP (dBm) = RSSI (dBm) -10*log (12*N)
where RSSI = Received Signal Strength Indicator
N: number of RBs across the RSSI is measured and depends on the BW
Significance :
RSRP is the most basic of the UE physical layer measurements and is the linear
average power (in watts) of the downlink reference signals (RS) across the channel
bandwidth for the Resource elements that carry cell specific Reference Signals.
Knowledge of absolute RSRP provides the UE with essential information about the
strength of cells from which path loss can be calculated and used in the algorithms
for determining the optimum power settings for operating the network. Reference
signal receive power is used both in idle and connected states
Range :- -44 to -140 dBm
• RSRP term is used for coverage same as RSCP in 3G
RSRQ :Reference signal receive quality
RSRQ = RSRP / (RSSI / N)
N is the number of resource blocks over which the RSSI is measured
RSSI is wide band power, including intra cell power, interference and noise.
Significance :-
It provides the Indication of Signal Quality . Measuring RSRQ becomes particularly
important near the cell edge when decisions need to be made, regardless of absolute

RSRP, to perform a handover to the next cell. Reference signal receive quality is
used only during connected states
Range :- -3 to -19.5 dB
• RSRQ term is used for Quality same as Ec/No in 3G.
• SINR :- Signal to Noise Ratio.
SINR = S / I + N
S -- Average Received Signal Power
I -- Average Interference power
N -- Noise Power
Significance : Is a way to measure the Quality of LTE Wireless Connections. As the
energy of signal fades with distance i.e Path Loss due to environmental parameters (
e.g. background noise , interfering strength of other simultaneous transmission)
• RSSI :- Received Signal Strength Indicator.
• < !--[if ppt]-->
• RSSI = wideband power = noise + serving cell power +
interference power
• RSSI=12*N*RSRP
• RSSI per resource block is measured over 12 resource elements.
N: number of RBs across the RSSI is measured and depends on the BW
Based on the above:
RSRP (dBm) = RSSI (dBm) -10*log (12*N)
• Significance :–
Is the parameter represents the entire received power including the
wanted power from the serving cell as well as all the co channel power
& other sources of noise
• CQI :- Channel Quality Indicator
• Range :- 1 to 15
Significance:
CQI is a measurement of the communication quality of wireless channels i.e. it
indicates the downlink mobile radio channel quality as experienced by the UE .CQI
can be a value representing a measure of channel quality for a given channel.
Typically, a high value CQI is indicative of a channel with high quality and vice versa.
• CQI is measured in the Dedicated mode only.
• < !--[if ppt]-->

• CQI depends on the RF conditions.
• < !--[if ppt]-->
• Better the CQI better the throughput will get and vice versa.
• PCI:- Physical Cell Id
Range :- 0 to 503
• Significance - PCI used to identify the cell & is used to transmit the data
• < !--[if ppt]-->
• PCI = PSS + 3*SSS
PSS is Primary Synchronization Signal ( Identifies Cell Id ).
PSS value can be 0, 1 & 2
SSS is Secondary Synchronization Signal ( identifies Cell Id
group).
SSS value can be 0 to 167.
• BLER :- Block Error Rate
• Block Error Ratio is defined as the ratio of the number of erroneous
blocks received to the total number of blocks transmitted
• < !--[if ppt]-->
Significance -
A simple method by which a UE can choose an appropriate CQI value could be based
on a set of Block Error Rate (BLER) thresholds . The UE would report the CQI value
corresponding to the Modulation Coding Schemes that ensures BLER ≤ 10% based
on the measured received signal quality
• < !--[if ppt]-->
• BLER is Calculated using Cyclic Redundancy error Checking method
High BLER leads to loss of Peak rates & efficiency
 BLER threshold should be low i.e. ≤ 10%
DDownlink Throughput
-I n E-UTRAN may use a maximum of 2 Tx antennas at the ENodeB and
2 Rx antennas at the UE ( MIMO ).
Significance - Target for averaged user throughput per MHz, 3 to 4 times
Release 6 HSDPA i.e Higher user throughput as compared to 3G ( Over 300 Mbps
downlink as compared to 14 Mbps in UMTS)

- The supported user throughput should scale with the spectrum
bandwidth.
Uplink Throughput
-I n E-UTRAN uses a maximum of a single Tx antenna at the UE and 2 Rx
antennas at the E Node B.
- Greater user throughput should be achievable using multiple Tx
antennas at the UE ( MIMO )
.
- Significance-
Target for averaged user throughput per MHz, 2 to 3 times Release 6 Enhanced
Uplink i.e Higher user throughput as compared to 3G (Over 50 Mbps Uplink as
compared to 5.76 Mbps in UMTS).The user throughput should scale with the
spectrum bandwidth provided that the maximum transmit power is also scaled.
WCDMA/3G Questions & Answers
General
< !--[if !supportLists]-->1. What is the experience and involvement in your
current and previous UMTS design projects?
Talk about your current and previous projects, your responsibilities, design objectives, tools used,
activities involved, challenges, objectives met, etc.
Link Budget
< !--[if !supportLists]-->2. What is a typical NodeB sensitivity level?
The service and load determines the NodeB sensitivity; in general, in a no -load condition, the sensitivity is
between -115dBm to -125dBm. For Ericsson, the NodeB sensitivity level is calculated at around:
CS12.2: -124 dBm
PS-64: -119 dBm
PS-128: -115 dBm
PS-384: -115 dBm

< !--[if !supportLists]-->3. What is a typical UE sensitivity level?
The service and load determines the UE sensitivity; in general, in no -load condition, the sensitivity is
between -105dBm and -120dBm. For Ericsson, the UE sensitivity level is calculated at around:
CS12.2: -119 dBm
PS-64: -112 dBm
PS-128: -110 dBm
PS-384: -105 dBm
HSDPA: -95 dBm
< !--[if !supportLists]-->4. What is a typical NodeB maximum output power?
The maximum NodeB output power is usually 20W or 40W, that is, 43dBm or 46dBm.
< !--[if !supportLists]-->5. What is UE maximum transmit power in your link
budget?
21dBm.
< !--[if !supportLists]-->6. What is a typical antenna gain?
The antenna gain depends on antenna model; in link budget we use around 17dBi.
< !--[if !supportLists]-->7. What is a typical maximum path loss?
The maximum path loss is dependent on the service and vendor recommendations; typically it is in
between 135 to 140dB for urban areas and between 150 to 160dB for rural areas.
< !--[if !supportLists]-->8. What is difference between dBi and dBd?
dBi is the gain in dB from isotropic source; dBd is the gain from a dipole source.
dBd + 2.15 = dBi.
< !--[if !supportLists]-->9. What is the difference between dB and dBm?
dBm is a unit of power level, measured in milli-watts in logarithm scale, that is,
dBm = 10 * log(W*1000) where W is the power in Watts
dB is not a unit, it is the difference in dBm.
< !--[if !supportLists]-->10. What is 0dBm?
0dBm = 1 milli-watt.
< !--[if !supportLists]-->11. How does TMA work?
A TMA reduces system noise, improves uplink sensitivity and leads to longer UE battery life.

Sensitivity is the minimum input power needed to get a suitable signal -to-noise ratio (SNR) at the output
of the receiver. It is determined by receiver noise figure, thermo noise power and required SNR. Thermo
noise power is determined by bandwidth and temperature, SNR is determined by modulation technique,
therefore the only variable is noise figure.
The cascading noise figure can be calculated by Friis equation (Herald Friis):
NFt = NF1 + (NF2-1)/G1 + (NF3-1)/(G1*G2) + ... + (NFi -1)/(G1*G2*...*Gi)
As the equation shows, the first block imposes the minimum and the most prominent noise figure on the
system, and the following blocks imposes less and less impact to the system provided the gains are
positive. Linear passive devices have noise figure equal to their loss. A TMA typically has a gain of 12dB.
There are typically top jumper, main feeder and a bottom jumper between antenna and BTS. A TMA
placed near antenna with a short jumper from antenna provides the best noise figure improvement – the
noise figure will be restricted to the top jumper loss (NF1) and TMA ((NF2-1)/G1), and the remaining
blocks (main feeder and bottom jumper) have little effect.
To summarize, a TMA has a gain that’s c lose to feeder loss.
< !--[if !supportLists]-->12. What are the pros and cons (advantages and
disadvantages) of TMA?
On the upside, a TMA reduces system noise, improves uplink sensitivity and leads to longer UE battery
life. On the downside, TMA imposes an additional insertion loss (typically 0.5dB) on the downlink and
increases site installation and maintenance complexity.
< !--[if !supportLists]-->13. What is typical TMA gain?
TMA typically has a 12 dB gain; however, the effective gain comes from noise figure reduction and the
gain is close or equivalent to the feeder loss.
< !--[if !supportLists]-->14. Why TMA are installed at the top near the
antenna and not the bottom near the NodeB?
Based on Friis Equation, having a TMA near the BTS will have the top jumper and main feeder losses
(noise figures) cascaded in and a TMA will not be able to help suppress the losses.
< !--[if !supportLists]-->15. What is UMTS chip rate?
3.84MHz.
< !--[if !supportLists]-->16. What is processing gain?
Processing gain is the ratio of chip rate over data bit rate, usually represented in decibel (dB) scale. For
example, with 3.84MHz chip rate and 12.2k data rate, the processing gain is:
PG12.2k = 10 * log (3,840,000 / 12,200) = 25dB
< !--[if !supportLists]-->17. What are the processing gains for CS and PS
services?
CS12.2: 25dB

PS-64: 18dB
PS-128: 15dB
PS-384: 10dB
HSDPA: 2dB
< !--[if !supportLists]-->18. How to calculate maximum number of users on a
cell?
To calculate the maximum number of users (M) on a cell, we need to know:
W: chip rate (for UMTS 3,840,000 chips per second)
EbNo: Eb/No requirement (assuming 3dB for CS-12.2k)
i: other-cell to in-cell interference ratio (assuming 60%)
R: user data rate (assuming 12,200 kbps for CS-12.2k)
η: loading fac tor (assuming 50%)
Take 12.2kbps as example:
M = W / (EnNo * (1 + i) * R) * η = 3,840,000 (3 * (1 + 0.6) * 1 2,200) * 0.5 = 32.8
The number of users could also be hard-limited by OVSF code space. Take CS12.2k for example:
< !--[if !supportLists]--> A CS-12.2k bearer needs 1 SF128 code.
< !--[if !supportLists]--> Total available codes for CS-12.2k = 128 – 2 (1 SF64) – 2 (4
SF256) = 124.
< !--[if !supportLists]--> Consider soft-handover factor of 1.8 and loading factor of 50%:
124 / 1.8 *.05 = 34 uers/cell.
< !--[if !supportLists]-->19. What is Eb/No?
By definition Eb/No is energy bit over noise density, i.e. is the ratio of the energy per information bit to
the power spectral density (of interference and noise) after dispreading.
Eb/No = Processing Gain + SIR
For example, if Eb/No is 5dB and processing gain is 25dB then the SIR should be -20dB or better.
< !--[if !supportLists]-->20. What are the Eb/No targets in your design?
The Eb/No targets are dependent on the service:
< !--[if !supportLists]--> On the uplink, typically CS is 5 to 6dB and PS is 3 to 4dB – PS is
about 2dB lower.

< !--[if !supportLists]--> On the downlink, typically CS has 6 to 7 dB and PS is 5 to 6dB –
PS is about 1dB lower.
< !--[if !supportLists]-->21. Why is Eb/No requirement lower for PS than for
CS?
PS has a better error correction capability and can utilize retransmission, therefore it can afford to a lower
Eb/No. CS is real-time and cannot tolerate delay so it needs a higher Eb/No to maintain a stronger RF
link.
< !--[if !supportLists]-->22. What is Ec/Io?
Ec/Io is the ratio of the energy per chip in CPICH to the total received power density (including CPICH
itself).
< !--[if !supportLists]-->23. Sometimes we say Ec/Io and sometimes we say
Ec/No, are they different?
Io = own cell interference + surrounding cell interference + noise density
No = surrounding cell interference + noise density
That is, Io is the total received power density including CPICH of its own cell, No is the total received
power density excluding CPICH of its own cell. Technically Ec/Io should be the correct measurement but,
due to equipment capability, Ec/No is actually measured. In UMTS, Ec/No and Ec/Io are often used
interchangeably.
< !--[if !supportLists]-->24. What is RSCP?
RSCP stands for Received Signal Code Power – the energy per chip in CPICH averaged over 512 chips.
< !--[if !supportLists]-->25. What is SIR?
SIR is the Signal-to-Interference Ratio – the ratio of the energy in dedicated physical control channel bits
to the power density of interference and noise after dispreading.
< !--[if !supportLists]-->26. What is the loading factor in your design?
The designed loading typically is 50%; however, sometimes a carrier may want to design up to 7 5% load.
< !--[if !supportLists]-->27. Give a simple definition of pole capacity?
The uplink noise increases with the loading exponentially. When the uplink noise approaches infinity then
no more users can be added to a cell – and the c ell loading is c lose to 100% and has reac hed its “pole
c apac ity”.
Mathematically, to calculate the uplink pole capacity we need to kno w:
W: chip rate (for UMTS 3,840,000 chips per second)
R: user data rate (assuming 12,200 kbps for CS-12.2k)
f: other-cell to in-cell interference ratio (assuming 65%)

EbNo: Eb/No requirement (assuming 5dB)
AF: Activity factor (assuming 50%)
Pole Capacity = (W/R) / ((1+f) * AF * 10^(EbNo/10)) = 120.6
To calculate the downlink pole capacity we also need to know:
α: downlink channels orthogonality factor (assuming 55%)
Pole Capacity = (W/R) / ((1 - α +f) * 10^(EbNo/10)) = 64.06
< !--[if !supportLists]-->28. What is typical pole capacity for CS-12.2, PS-64,
PS-128 and PS-384?
With same assumptions as above:
< !--[if !supportLists]--> CS-12.2k: 120.6 (UL), 64.1 (DL).
< !--[if !supportLists]--> PS-64k: 34.8 (UL), 12.8(DL).
< !--[if !supportLists]--> PS-128k: 16.2 (UL), 8.4 (DL).
< !--[if !supportLists]--> PS-384k: 16.2 (UL), 2.8 (DL).
PS-384k has only 128k on the uplink, therefore the uplink capacity is the same for both.
< !--[if !supportLists]-->29. How many types of handovers are there in
UMTS?
Soft handover, softer handover, inter-frequency handover, inter-RAT handover, inter-RAT cell change
(UE moving out of UMTS coverage into GSM/GPRS/EGDGE coverage).
< !--[if !supportLists]-->30. What is soft handover and softer handover?
< !--[if !supportLists]--> Soft handover: when a UE is connected to cells owned by
different NodeB.
< !--[if !supportLists]--> Softer handover: when a UE is connected to cells owned by the
same NodeB.
< !--[if !supportLists]-->31. How does soft/softer handover work?
< !--[if !supportLists]--> Soft/softer handover downlink: UE rake receiver performs
maximum ratio combining, i.e. UE combines multi-path signals and form a stronger signal.
< !--[if !supportLists]--> Soft handover uplink: RNC performs selection combining, i.e.
RNC selects the better signal coming from multiple NodeB.
< !--[if !supportLists]--> Softer handover uplink: NodeB performs maximum ratio
combining, i.e. NodeB rake receiver combines signals from different paths and forms a stronger signal.

32. Wh y is th ere “soft h andover gain”?
Soft handover gain comes from the following:
< !--[if !supportLists]--> Macro diversity gain over slow fading.
< !--[if !supportLists]--> Micro diversity gain over fast fading.
< !--[if !supportLists]--> Downlink load sharing over multiple RF links. By maintaining
multiple links each link could transmit at a lower power, resulting in lower interference therefore a gain.
< !--[if !supportLists]-->33. Brief describe the advantages and disadvantages
of soft handover?
Advantages:
< !--[if !supportLists]--> Overcome fading through macro diversity.
< !--[if !supportLists]--> Reduced Node B power which in turn decreases interference
and increases capacity.
< !--[if !supportLists]--> Reduced UE power (up 4dB), decreasing interference and
increasing battery life.
Disadvantages:
< !--[if !supportLists]--> UE using several radio links requires more channelization
codes, and more resources on the Iub and Iur interfaces.
< !--[if !supportLists]-->34. What are fast fading and slow fading?
Fast fading is also called multi-path fading, as a result of multi-path propagation. When multi-path
signals arriving at a UE, the constructive and destructive phases create a variation in signal strength.
Slow fading is also called shadowing. When a UE moves away from a cell the signal strength drops down
slowly.
< !--[if !supportLists]-->35. What are fast fading margin and slow fading
margin?
To factor in the fast fading and slow fading, we need to have a margin in the link budget and they are
called fast fading margin and slow fading margin.
In link budget, the fast fading margin is usually set to 2-3; slow fading margin is set to 7 -10.
< !--[if !supportLists]-->36. What is a typical soft handover gain in your link
budget?
 CS-12.2k: 3dB (UL), 2dB (DL).
< !--[if !supportLists]--> PS-64k: 1dB (UL), 0dB (DL).

< !--[if !supportLists]-->37. What is the percentage in time a UE is expected to
be in soft or softer handover?
Typically a UE should be in soft handover mode at no more than 35 to 40% of the time; in softer handover
mode at about 5% of the time.
< !--[if !supportLists]-->38. What is a typical EiRP?
The EiRP depends NodeB transmit power, cable and connector loss and antenna gain. With a sample
system of 43dBm transmit power, a 3dB cable and connector loss and a 17dBi antenna gain, the EiRP = 43
– 3 + 17 = 57dBm.
< !--[if !supportLists]-->39. How much power usually a NodeB is allocated to
control channels?
The power allocated to control channels may depend on equipment vendor recommendation. Typically no
more than 20% of the total NodeB power is allocated to control channels, including CPICH. However, if
HSDPA is deployed on the same carrier then the total power allocated to control channel may go up to 25
to 30% because of the additional HSDPA control channels required.
< !--[if !supportLists]-->40. What is a typical CPICH power?
CPICH power typically takes about 10% of the total NodeB power. For a 20W (43dBm) NodeB, CPICH is
around 2W (33dBm).
In urban areas where in-building coverage is taken care of by in-building installations, the CPICH may
sometimes go as low as 5% because:
< !--[if !supportLists]--> The coverage area is small since users are close to the site, and
< !--[if !supportLists]--> More power can be allocated to traffic channels.
< !--[if !supportLists]-->41. How much is your HSDPA (max) link power?
HSDPA link power is typically 4 to 5dB below the maximum NodeB maximum output power. For
example, for 43dBm maximum NodeB power the HSDPA link power is 39dBm.
< !--[if !supportLists]-->42. Consider downlink only, what are the major
components in calculating maximum path loss, starting from NodeB?
< !--[if !supportLists]--> NodeB CPICH transmit power.
< !--[if !supportLists]--> Jumper and feeder connector loss.
< !--[if !supportLists]--> Antenna gain.
< !--[if !supportLists]--> Over-the-air loss.

< !--[if !supportLists]--> Building / vehicle penetration loss.
< !--[if !supportLists]--> Body loss.
< !--[if !supportLists]--> Etc.
< !--[if !supportLists]-->43. What is maximum path-loss?
The maximum path-loss is how much signal is allowed to drop from a transmitter to a receiver and
maintains as good signal.
< !--[if !supportLists]-->44. Simple link budget: with a 30dBm CPICH and a -
100dBm UE sensitivity, ignoring anything in between, what is the maximum path loss?
30 – (–100) = 30 + 100 = 130dB.
< !--[if !supportLists]-->45. Suppose I have a maximum path-loss of 130dBm,
what is the new path-loss if a 5dB body loss is added?
125dB.
< !--[if !supportLists]-->46. What is channelization code?
Channelization codes are orthogonal codes used to spread the signal and hence provides channel
separation, that is, channelization codes are used to separate channels from a cell.
< !--[if !supportLists]-->47. How many channelization codes are available?
The number of channelization codes available is dependent on the length of code. In the uplink the length
is defined as between 4 and 256. In the downlink the length is defined as between 4 and 512.
< !--[if !supportLists]-->48. Are channelization codes mutually orthogonal? If
so, wh y is “Orth ogonality Fac tor” required in the link budget?
Yes, channelization codes are mutually orthogonal. Nonetheless, due to multi-path with variable time
delay, channels from the same cell are no longer perfectly orthogonal and may interfere with each other.
A “Downlink Orthogonality Fac tor”, ty pically 5 0 -60%, is therefore needed in the link budget to account
for the interference – and hence reduces pole capacity.
< !--[if !supportLists]-->49. What is scrambling code? How many scrambling
codes there are?
Scrambling codes are used to separate cells and UEs from each other, that is, each cell or UE should have
a unique scrambling code. There are 512 scrambling codes on the downlink and millions on the uplink.
< !--[if !supportLists]-->50. Wh at is sc ram bling “c ode group”?
The 512 scrambling codes are divided into 64 code groups – each code group has 8 scrambling codes.
Code group i (i = 0 to 63) has codes from i*8 to (i+1)*8-1, i.e. (0-7) (8-1 5)…(504-511).

< !--[if !supportLists]-->51. Do you divide scrambling code groups into
subgroups? Please give an example.
Yes, we divide the 64 code groups into subgroups:
< !--[if !supportLists]--> Macro layer group: 24 code groups reserved for macro (outdoor)
sites.
< !--[if !supportLists]--> Micro layer group: 16 code groups reserved for micro (in-building)
sites.
< !--[if !supportLists]--> Expansion group: 24 code groups reserved for future expansion
sites.
< !--[if !supportLists]-->52. Which service usually needs higher power, CS or
PS?
Consider downlink and take CS-12.2 and PS-384k for example. The processing gain is 25 for CS-12.2 and
10 for PS-384. The Eb/No requirement is 7 for CS-12.2 and 5 for PS-384. Therefore the power
requirement is higher for CS-12.2 than PS-384.
< !--[if !supportLists]-->53. What is Eb/No requirement for HSDPA?
The Eb/No requirement for HSDPA varies with user bit rate (data rate), typically 2 for 7 68kbps and 5 for
2Mbps.
< !--[if !supportLists]-->54. Wh at is “noise rise”? Wh at does a h igh er no ise
rise mean in terms of network loading?
For every new user added to the service, additional noise is added to the network. That is, each new user
c auses a “noise rise”. In theory, the “noise rise” is defined as the ratio of total received wideband power to
the noise power. Higher “noise rise” v alue implies more users are allowed on the network, and eac h user
has to transmit higher power to overcome the higher noise level. This means smaller path loss can be
tolerated and the cell radius is reduced. To summarize, a higher noise rise means higher capacity and
smaller footprint, a lower noise rise means smaller capacity and bigger footprint.
< !--[if !supportLists]-->55. Wh at is “pilot pollu tion”?
Simply speaking, when the number of strong cells ex ceeds the ac tive set size, there is “pilot pollution” in
the area. Typically the active set size is 3, so if there are more than 3 strong cells then there is pilot
pollution.
Definition of “strong c ell”: pilots within the handover window size from the strongest cell. Typical
handover window size is between 4 to 6dB. For example, if there are more than 2 cells (besides the
strongest cell) within 4dB of the strongest cell then there is pilot pollution.
< !--[if !supportLists]-->56. What is a typical handover window size in your
network?
A handover window size is usually between 4 to 6dB.

< !--[if !supportLists]-->57. Wh at is “soft h andover” and “softer h andover”?
“Soft handov er” is when UE has c onnec tion to multiple c ells on different NodeB.
“Softer handover” is when UE has c onnec tion to multiple c ells on same NodeB.
In downlink a UE can combine signals from different cells, improving the signal quality. For uplink and
soft handover, RNC selects the best signal from different NodeB. For uplink and softer handover, a NodeB
combines the signal from different sectors.
< !--[if !supportLists]-->58. During a handover, if one cell sends a power
down request and two cells send a power up request, shall the UE power up or power
down?
Power down. As long as a good link can be maintained it is not necessary to power up in order to maintain
multiple links. Maintaining unnecessary multiple links increases noise rise and shall be avoided.
< !--[if !supportLists]-->59. Suppose we are designing a CS network and a PS
network, is there a major difference in the design consideration?
Server dominance is the key difference. In a CS network we shall limit the number of strong servers in any
given area to no more than the active set size to avoid pilot pollution (in the downlink). In a PS network,
howev er, there isn’t soft handover in the downlink so the server dominance is v ery important – meaning
ideally there should be only one dominant server in a given area.
< !--[if !supportLists]-->60. What is the active set size on your network?
3.
< !--[if !supportLists]-->61. How many fingers does a UE rake receiver have?
4.
< !--[if !supportLists]-->62. Wh at is “c om pressed m ode”?
Before UE can perform inter-frequency or IRAT handover, it needs to have some time to lock on to the
control channel of the other frequency or system and listen to the broadcast information. Certain idle
periods are created in radio frames for this purpose and is c alled “compressed mode”.
< !--[if !supportLists]-->63. Describe the power control schemes in UMTS?
< !--[if !supportLists]--> Open loop – for UE to access the network, i.e. used at call setup
or initial access to set UE transmit power.
< !--[if !supportLists]--> Closed outer loop: RNC calculates the SIR target and sends the
target to NodeB (every 10ms frame).
< !--[if !supportLists]--> Closed inner loop: NodeB sends the TPC bits to UE to increase
or decrease the power at 1,500 times a second.
< !--[if !supportLists]-->64. What is the frequency of power control (how fast
is power control)?

< !--[if !supportLists]--> Open loop: depends on parameter setting:
T300 – time to wait between RRC retries (100ms to 8000 ms, typical 1500ms)
< !--[if !supportLists]--> Closed outer loop: 100 times a second.
< !--[if !supportLists]--> Closed inner loop: 1,500 times a second.
< !--[if !supportLists]-->65. Briefly describe why open loop power control is
needed and how it works?
< !--[if !supportLists]--> When a UE needs to access to the network it uses RACH to
begin the process.
< !--[if !supportLists]--> RACH is a shared channel on the uplink used by all UE,
therefore may encounter contention (collision) during multiple user access attempts and interfere with
each other.
< !--[if !supportLists]--> Each UE must estimate the amount of power to use on the
access attempt since no feedback from the NodeB exists as it does on the dedicated channel.
< !--[if !supportLists]--> The purpose of open loop power control is to minimize the
chance of collision and minimize the initial UE transmit power to reduce interference to other UE.
transmit power = Primary_CPICH_Power – CPICH_RSCP + UL_Interferrnce + constant_Value_Cprach
< !--[if !supportLists]--> Instead of sending the whole message, a “test” (preamble) is
sent.
< !--[if !supportLists]--> Wait for answer from NodeB.
< !--[if !supportLists]--> If no answer from NodeB increase the power.
< !--[if !supportLists]--> Try and try until succeed or timeout.
< !--[if !supportLists]-->66. Wh at is power c ontrol “h eadroom”?
Power c ontrol “headroom” is also c alled “power rise”. In a non -fading channel the UE needs to transmit a
certain fixed power. In a fading chennel a UE reacts to power control commands and usually increases the
transmit power. The difference between the average power levels of fading and non-fading channels is
c alled “power rise” or “headroom”.
< !--[if !supportLists]-->67. When in 3-way soft handover, if a UE receives
power down request from one cell and power up request from the other 2 cells, should the
UE power up or down and why?
Power down. Maintaining one good link is sufficient to sustain a call and having unnecessary stronger
links creates more interference.
< !--[if !supportLists]-->68. Suppose two UE are served by the same cell, the
UE with weaker link (poor RF c ondition) u ses m ore “c apac ity”, wh y does th is mean?

The UE with weaker RF link will require NodeB to transmit higher traffic power in order to reach the UE,
resulting in less power for other UE – therefore c onsumes more “c apacity”.
< !--[if !supportLists]-->69. Under what circumstances can a NodeB reach its
capacity? What are the capacity limitations?
NodeB reaches its maximum transmit power, runs out of its channel elements, uplink noise rise reaches
its design target, etc.
< !--[if !supportLists]-->70. Wh at is “c ell breath ing” and wh y?
The cell coverage shrinks as the loading increases, this is called cell breathing.
In the uplink, as more and more UE are served by a cell, each UE needs to transmit higher power to
compensate for the uplink noise rise. As a consequence, the UE with weaker link (UE at greater distance)
may not have enough power to reach the NodeB – therefore a coverage shrinkage.
In the downlink, the NodeB also needs to transmit higher power as more UE are being served. As a
consequence UE with weaker link (greater distance) may not be reachable by the NodeB.
< !--[if !supportLists]-->71. Is UMTS an uplink-limited or downlink-limited
system?
A UMTS system could be either uplink-limited or downlink-limited depending on the loading. In a lightly
loaded system, the UE transmit power sets a coverage limitation therefore it is uplink-limited. In a heavily
loaded system, the NodeB transmit power limits the number of UEs it can serve therefore it is downlink-limited.
< !--[if !supportLists]-->72. What is the impact of higher data rate on
coverage?
Higher data rate has lower processing gain and therefore a NodeB needs to transmit more power to meet
the required Eb/No; this means the coverage is smaller for higher data rate.
< !--[if !supportLists]-->73. What is OCNS?
OCNS stands for Orthogonal Channel Noise Simulator. It is a simulated network load usually by
increasing the noise rise figure in the NodeB.
UTRAN
< !--[if !supportLists]-->74. What are the interfaces between each UTRAN
component?
Uu: UE to NodeB
Iub: NodeB to RNC
Iur: RNC to RNC
Iu: RNC to MSC

< !--[if !supportLists]-->75. Briefly describe the UE to UTRAN protocol stack
(air interface layers).
The radio interface is divided into 3 layers:
< !--[if !supportLists]-->1. Physical layer (Layer 1, L1): used to transmit data over the
air, responsible for channel coding, interleaving, repetition, modulation, power control, macro -diversity
combining.
< !--[if !supportLists]-->2. Link layer (L2): is split into 2 sub-layers – Medium Access
Control (MAC) and Radio Link Control (RLC).
< !--[if !supportLists]--> MAC: responsible for multiplexing data from multiple
applications onto physical channels in preparation for over -the-air transmition.
< !--[if !supportLists]--> RLC: segments the data streams into frames that are small
enough to be transmitted over the radio link.
< !--[if !supportLists]-->3. Upper layer (L3): vertically partitioned into 2 planes: control
plane for signaling and user plan for bearer traffic.
< !--[if !supportLists]--> RRC (Radio Resource Control) is the control plan protocol:
controls the radio resources for the access network.
In implementation:
< !--[if !supportLists]-->1. UE has all 3 layers.
< !--[if !supportLists]-->2. NodeB has Physical Layer.
< !--[if !supportLists]-->3. RNC had MAC layer and RRC layer.
< !--[if !supportLists]-->76. Briefly describe UMTS air interface channel types
and their functions.
There are 3 types of channels across air interface – physical channel, transport channel and logical
channel:
< !--[if !supportLists]-->1. Physical Channel: carries data between physical layers of UE
and NodeB.
< !--[if !supportLists]-->2. Transport Channel: carries data between physical layer and
MAC layer.
< !--[if !supportLists]-->3. Logical Channel: carries data between MAC layer and RRC
layer.
< !--[if !supportLists]-->77. Give some examples of Physical, Transport and
Logical channels.
< !--[if !supportLists]-->1. Logical Channel:

< !--[if !supportLists]--> Control channel: BCCH, PCCH, CCCH, DCCH.
< !--[if !supportLists]--> Traffic channel: DTCH, CTCH.
< !--[if !supportLists]-->2. Transport Channel:
< !--[if !supportLists]--> Common control channel: BCH, FACH, PCH, RACH, CPCH.
< !--[if !supportLists]--> Dedicated channel: DCH, DSCH.
< !--[if !supportLists]-->3. Physical Channel:
< !--[if !supportLists]--> Common control channel: P-CCPCH, S-CCPCH, P-SCH, S-SCH,
CPICH, AICH, PICH, PDSCH, PRACH, PCPCH, CD/CA-ICH.
< !--[if !supportLists]--> Dedicated channel: DPDCH, DPCCH.
< !--[if !supportLists]-->78. What are the RRC operation modes?
Idle mode and connected mode.
< !--[if !supportLists]-->79. What are the RRC states?
There are 4 RRC States: Cell_DCH, Cell_FACH, URA_PCH and Ce ll_PCH.
URA = UTRAN Registration Area.
 
< !--[if !supportLists]-->80. What are transparent mode, acknowledged mode
and unacknowledged mode?
< !--[if !supportLists]--> Transparent mode corresponds to the lowest service of the
RLC layer, no controls and no detection of missing data.
< !--[if !supportLists]--> Unacknowledged mode offers the possibility of segment and
concatenate of data but no error correction or retransmission therefor e no guarantee of delivery.

< !--[if !supportLists]--> Acknowledged mode offers, in addition to UM mode
functions, acknowledgement of transmission, flow control, error correction and retransmission.
< !--[if !supportLists]-->81. Which layer(s) perform ciphering function?
RRC – for acknowledged mode (AM) and unacknowledged mode (UM).
MAC – for transparent mode (TM).
< !--[if !supportLists]-->82. What is OVSF?
Orthogonal Variable Spreading Factor.
< !--[if !supportLists]-->83. How many OVSF code spaces are available?
< !--[if !supportLists]--> Total OVSF codes = 256.
< !--[if !supportLists]--> Reserved: 1 SF64 for S-CCPCH, 1 SF256 for CPICH, P-CCPCH,
PICH and AICH each.
< !--[if !supportLists]--> Total available code space = 256 – 4 (1 SF64) – 4 (4 SF256) =
248.
< !--[if !supportLists]-->84. Can code space limit the cell capacity?
Yes, cell capacity can be hard-limited by code space. Take CS-12.2k for example:
< !--[if !supportLists]--> A CS-12.2k bearer needs 1 SF128 code.
< !--[if !supportLists]--> Total available codes for CS-12.2k = 128 – 2 (1 SF64) – 2 (4
SF256) = 124.
< !--[if !supportLists]--> Consider soft-handover factor of 1.8: 124 / 1.8 = 68 uers/cell.
< !--[if !supportLists]-->85. Can a u ser h av e OVSF c ode as “1111”?
No, bec ause “1111…” (256 times) is used by CPICH.
< !--[if !supportLists]-->86. What are the symbol rates (bits per symbol) for
BPSK, QPSK, 8PSK and 16QAM?
< !--[if !supportLists]--> BPSK: 1.
< !--[if !supportLists]--> QPSK: 2.
< !--[if !supportLists]--> 8PSK: 3.
< !--[if !supportLists]--> 16QAM: 4.
< !--[if !supportLists]-->87. Briefly describe UMTS frame structure.
< !--[if !supportLists]--> UMTS frame duration = 10ms.

< !--[if !supportLists]--> Each frame is divided into 15 timeslots.
< !--[if !supportLists]--> Each timeslot is divided into 2560 chips.
< !--[if !supportLists]--> Therefore 2560 chips/TS * 15 TS/frame * (1000ms/10ms)
frame/sec = 3,840,000 chip/sec.
< !--[if !supportLists]-->88. What is cell selection criterion?
Cell selection is based on:
< !--[if !supportLists]--> Qmean: the average SIR of the target cell.
< !--[if !supportLists]--> Qmi n: minimum required SIR.
< !--[if !supportLists]--> Pcompensation: a correction value for difference UE classes.
S = Qmean - Qmi n - Pcompensation
< !--[if !supportLists]--> If S>0 then the cell is a valid candidate.
< !--[if !supportLists]--> A UE will camp on the cell with the highest S.
< !--[if !supportLists]-->89. Briefly describe Capacity Management and its
functions:
Capacity Management is responsible for the control of the load in the cell. It consists of 3 main functions:
< !--[if !supportLists]--> Dedicated Monitored Resource Handling: tracks utilization of
critical resources of the system.
< !--[if !supportLists]--> Admission Control: accepts/refuses admission requests based
on the current load on the dedicated monitored resour ces and the characteristics of the request
< !--[if !supportLists]--> Congestion Control: detects/resolves overload situations
Planning
< !--[if !supportLists]-->90. What are the major 4 KPIs in propagation model
tuning and typical acceptable values?
The 4 KPIs are standard deviation error, root mean square error, mean error and correlation coefficient.
The typical acceptable values are:
< !--[if !supportLists]--> Standard deviation error: the smaller the better, usually 7 to
9dB.
< !--[if !supportLists]--> Mean error: the smaller the better, usually 2 to3.
< !--[if !supportLists]--> Root mean square error: the smaller the better, usually

< !--[if !supportLists]--> Correlation coefficient: the larger the better, usually 70% to
90%.
< !--[if !supportLists]-->91. What is the minimum number of bins required
for a certain propagation model?
The more bins the more likely to come up with a good model. Usually a minimum of 2,000 bines is
considered acceptable, but sometimes as low as 500 bins may be accepted.
< !--[if !supportLists]-->92. How many scrambling codes are there?
There are 512 scrambling codes in the downlink and 16,777,216 codes in the uplink.
< !--[if !supportLists]-->93. How many scrambling code groups are there for
downlink?
There are 64 code groups, each group has 8 scrambling codes.
< !--[if !supportLists]-->94. Can we assign same scrambling codes to sister
sectors (sectors on same site)?
No, because scrambling code on the downlink is used for cell identity. As a requirement, scrambling codes
have to maintain a safe separation to avoid interference.
< !--[if !supportLists]-->95. Are scrambling codes orthogonal?
No, scrambling codes are not orthogonal since they are not synchronized at each receiver. They are
pseudo random sequences of codes.
< !--[if !supportLists]-->96. Can we assign scrambling codes 1, 2 and 3 to
sister sectors?
Yes.
< !--[if !supportLists]-->97. In IS-95 we have a PN reuse factor (PN step size)
and th erefore c annot u se all 5 12 PN c odes, wh y isn’t it necessary for UMT S sc ram bling
codes?
Because IS-95 is a synchronized network, different PN codes have the same code sequence with a time
shift, therefore we need to maintain a certain PN step size to avoid multi -path problem. For example, if
two sectors in the neighborhood have a small PN separation then signal arriving from cell A may run into
the time domain of cell B, causing interference.
UMTS, on the other hand, is not a synchronized network and all scrambling codes are mutually
orthogonal so no need to maintain a step size.
< !--[if !supportLists]-->98. What are coverage thresholds in your UMTS
design and why?
The coverage thresholds are based on UE sensitivity, fading and penetration loss. Assuming UE sensitivity
of -110dBm, fade margin of 5dB:

< !--[if !supportLists]--> Outdoor: -110dBm sensitivity + 5dB fade margin = -105dBm.
< !--[if !supportLists]--> In-vehicle: -110dBm + 5dB + 8dB in-vehicle penetration loss = -
97 dBm.
< !--[if !supportLists]--> In-building: -110dBm + 5dB + 15dB in-building penetration loss
= -90dBm.
< !--[if !supportLists]-->99. What is the Ec/Io target in your design?
The Ec/Io target typically is between -12 to -14dB. However, if a network is designed for data then the
Ec/Io target could go higher to around -10dB because server dominance is more critical for a data
network – sinc e there isn’t software in the downlink.
< !--[if !supportLists]-->100. Wh at is“Monte Carlo sim ulation”?
Since UMTS coverage is dependent on the loading, static coverage and quality analysis (RSCP and Ec/Io)
represents the network performance in no-load condition. Monte Carlo simulation is therefore used to
illustrate network performance under simulated loading consition.
< !--[if !supportLists]-->101. What is the key difference between a static
analysis and a Monte Carlo simulation?
Static analysis can only show RSCP and Ec/Io in no -load condition. Monte Carlo simulation not only can
show RSCP and Ec/Io in simulated loading condition but also can show many more others: mean served,
cell loading, uplink and downlink capacity limits reached, etc.
< !--[if !supportLists]-->102. What should be run first (what information
should be ready and loaded) before running a Monte Carlo simulation?
Before running Monte Carlo simulation, the following should be completed or in place.
< !--[if !supportLists]--> Run prediction.
< !--[if !supportLists]--> Spread the traffic.
< !--[if !supportLists]--> Define terminal types.
< !--[if !supportLists]-->103. How many snap shots and iteration do you
usually have when running Monte Carlo simulation?
(Depend on software tool recommendations).
< !--[if !supportLists]-->104. Wh at are th e design KPI ’s?
(RSCP, Ec/Io, mean served, soft handover ratio…)
< !--[if !supportLists]-->105. What plots do you usually check after running
Monte Carlo for trouble spots?
(RSCP, Ec /Io, service probability, reasons for failure…)

< !--[if !supportLists]-->106. What are the typical reasons of failure in Monte
Carlo simulation?
< !--[if !supportLists]--> Downlink Eb/No failure (Capacity).
< !--[if !supportLists]--> Downlink Eb/No failure (Range).
< !--[if !supportLists]--> Uplink Eb/No failure.
< !--[if !supportLists]--> Low pilot SIR.
< !--[if !supportLists]--> Noise rise limit reached.
< !--[if !supportLists]-->107. Wh at does“traffic spread” m ean?
“Traffic spread” means spreading traffic (number of terminals) in a c ell c overage area.
< !--[if !supportLists]-->108. Do you use live traffic or even-load traffic in
your design?
(Depends).
Optimization
< !--[if !supportLists]-->109. What are the optimization tools you use?
Drive test, analysis, others?
< !--[if !supportLists]-->110. Are System Information Blocks (SIB)
transmitted all the time?
No, system information block is multiplexed with synchronization channel. Synchronization channel
occupies the first time slot (TS) and SIB occupies the other 9 time slots.
< !--[if !supportLists]-->111. How does UE camp (synchronize) to a NodeB?
< !--[if !supportLists]-->1. UE uses the primary synchronization channel (P-SCH) for slot
alignment (TS synchronization).
< !--[if !supportLists]-->2. After aligning to NodeB time slot, UE then uses secondary
synchronization channel (S-SCH) to obtain frame synchronization and scrambling code group
identification.
< !--[if !supportLists]-->3. UE then uses scrambling code ID to obtain CPICH, thus
camping to a NodeB.
< !--[if !supportLists]-->112. What could be the cause of soft handover
failure?
< !--[if !supportLists]--> UE issue.

< !--[if !supportLists]--> Resource unavailable at target NodeB.
< !--[if !supportLists]--> Inadequate SHO threshold defined.
< !--[if !supportLists]-->113. What are the three sets in handover?
The 3 sets in handover are:
< !--[if !supportLists]--> Active set – the list of cells which are in soft handover with UE.
< !--[if !supportLists]--> Monitored set –the list of cells not in active set but RNC has told
UE to monitor.
< !--[if !supportLists]--> Detected set –list of cells detected by the UE but not configured
in the neighbor list.
< !--[if !supportLists]-->114. What are the major differences between GSM
and UMTS handover decision?
GSM:
< !--[if !supportLists]--> Time-based mobile measures of RxLev and RxQual – mobile
sends measurement report every SACH period (480ms).
< !--[if !supportLists]--> BSC instructs mobile to handover based on these reports.
UMTS:
< !--[if !supportLists]--> Event-triggered reporting – UE sends a measurement report
only on c ertain event “triggers”.
< !--[if !supportLists]--> UE plays more part in the handover decision.
< !--[if !supportLists]-->115. What are the events 1a, 1b, 1c, etc.?
< !--[if !supportLists]--> e1a – a Primary CPICH enters the reporting range, i.e. add a cell
to active set.
< !--[if !supportLists]--> e1b – a primary CPICH leaves the reporting range, i.e. removed
a cell from active set.
< !--[if !supportLists]--> e1c – a non-active primary CPICH becomes better than an active
primary CPICH, i.e. replace a cell.
< !--[if !supportLists]--> e1d: change of best cell.
< !--[if !supportLists]--> e1e: a Primary CPICH becomes better than an absolute
threshold.

< !--[if !supportLists]--> e1f: a Primary CPICH becomes worse than an absolute
threshold.
< !--[if !supportLists]-->116. What are event 2a-2d and 3a-3d?
Events 2a-2d are for inter-frequency handover measurements and events 3a-3d are for IRAT handover
measurements.
< !--[if !supportLists]--> e3a: the UMTS cell quality has moved below a threshold and a
GSM cell quality had moved above a threshold.
< !--[if !supportLists]--> e3b: the GSM cell quality has moved below a threshold.
< !--[if !supportLists]--> e3c: the GSM cell quality has moved above a threshold.
< !--[if !supportLists]--> e3d: there was a change in the order of best GSM cell list.
< !--[if !supportLists]-->117. Wh at m ay h appen wh en th ere’s a m issing
neighbor or an incorrect neighbor?
< !--[if !supportLists]--> Access failure and handover failure: may attempt to access to a
wrong scrambling code.
< !--[if !supportLists]--> Dropped call: UE not aware of a strong scrambling code, strong
interference.
< !--[if !supportLists]--> Poor data throughput.
< !--[if !supportLists]--> Poor voice quality.
< !--[if !supportLists]-->118. What can we try to improve when access failure
is high?
When access failure is high we can try the following to improve RACH performance:
< !--[if !supportLists]--> Increase maximum UE transmit power allowed:
Max_allowed_UL_TX_Power.
< !--[if !supportLists]--> Increase power quickly: power_Offset_P0.
< !--[if !supportLists]--> Increase number of preambles sent in a given preamble cycle:
preamble_Retrans_Max.
< !--[if !supportLists]--> Increase the number of preamble cycles: max_Preamble_Cycle.
< !--[if !supportLists]--> Increase number of RRC Connection Request retries: N300.
< !--[if !supportLists]-->119. What are the conditions you typically set to
trigger IRAT handover?

RSCP and Ec/Io are used to trigger IRAT handover:
< !--[if !supportLists]--> RSCP ≤ -100dBm.
< !--[if !supportLists]--> Ec /Io ≤ -16dBm.
< !--[if !supportLists]-->120. What are the typical KPIs you use to measure a
network and what criteria?
< !--[if !supportLists]--> A c c ess failure rate (≤ 2%).
< !--[if !supportLists]--> Call setup time (CS: over 95% of the time < 6-second for mobile-to-
PSTN, 9-second for mobile-mobile. PS: over 95% of the time< 5-second).
< !--[if !supportLists]--> Dropped c all rate (≤ 2%).
< !--[if !supportLists]--> BLER: ov er 95% of the bloc ks ≤ 2%.
< !--[if !supportLists]--> Average DL/UL throughput for PSD: 210kbps for loaded,
240kbps for unloaded.
< !--[if !supportLists]-->121. What is the typical UE transmit power?
Varies - most of the time below 0dBm.
< !--[if !supportLists]-->122. Have your used Ericsson TEMS? If so:
< !--[if !supportLists]--> Do you know how to create command sequence?
< !--[if !supportLists]--> What are the call sequences you typically have? CS long call, CS
short call, PSD call, etc.
< !--[if !supportLists]--> What are the typical commands you have for CS and PS call?
< !--[if !supportLists]--> Do you regularly stop and restart a new log file? Why and when
to stop and start a new file?
< !--[if !supportLists]--> How do you stop a log file? Stop command sequence first, wait
and make sure all equipment are in idle mode before stop logging.
< !--[if !supportLists]-->123. Did you work on neighbor prioritization?
< !--[if !supportLists]-->124. What is the typical event sequence of IRAT
Handover from 3G to 2G
< !--[if !supportLists]--> Event 2d –entering into compressed mode – measurement of
2G candidates – Event 3a –Verification of 2G resources – Handover from UTRAN Command from 3G
RNC to UE
< !--[if !supportLists]-->125. What are the possible causes for an IRAT
Failure?

< !--[if !supportLists]--> Missing 2G relations
< !--[if !supportLists]--> Non availability of 2G Resources
< !--[if !supportLists]--> Poor 2G Coverage
< !--[if !supportLists]--> Missing 3G Relations
< !--[if !supportLists]-->126. What is Paging Success Ratio? What is the
typical PSR that you have seen in a UMTS network?
< !--[if !supportLists]--> PSR – Paging Responses to the Paging Attempts
< !--[if !supportLists]--> About 90%
< !--[if !supportLists]-->127. What are the possible causes for a lower PSR?
< !--[if !supportLists]--> Non-continuous RF Coverage – UE going in and out of coverage
area frequently
< !--[if !supportLists]--> V ery High‘Periodic Location Update Timer’ – Keeping UEs in
VLR long time after it moved out of coverage
< !--[if !supportLists]--> Lower Paging Channel Power
< !--[if !supportLists]--> Access Channel Parameter Issues
< !--[if !supportLists]--> Delayed Location Update when crossing the LA / CN
Boundaries
< !--[if !supportLists]-->128. What are the possible causes for a Drop Call on
a UMTS network?
< !--[if !supportLists]--> Poor Coverage (DL / UL)
< !--[if !supportLists]--> Pilot Pollution / Pilot Spillover

< !--[if !supportLists]--> Missing Neighbor
< !--[if !supportLists]--> SC Collisions
< !--[if !supportLists]--> Delayed Handovers
< !--[if !supportLists]--> No resource availability (Congestion) for Hand in
< !--[if !supportLists]--> Loss of Synchronization
< !--[if !supportLists]--> Fast Fading
< !--[if !supportLists]--> Delayed IRAT Triggers
< !--[if !supportLists]--> Hardware Issues
< !--[if !supportLists]--> External Interference
< !--[if !supportLists]-->129. A UE is served by 2 or 3 SC in AS. It is identifying
a SC from 3rd tier, Stronger and meets the criteria for Event1a or Event1c. But SHO did not
happen because of missing neighbor relations? How do you optimize this issu e?
< !--[if !supportLists]--> Study the Pilot spillover from the 3rd Tier SC and control its
coverage
< !--[if !supportLists]--> Even after controlling the coverage, if the spillover is there, Add
the neighbor.
< !--[if !supportLists]-->130. A UE is served by 2 SC in AS, a SC is coming in to
Monitored Set and Event1a is triggered. But UE is not receiving Active Set Update from
NodeB and the call drops. What could be possible causes for this drop?
< !--[if !supportLists]--> Delayed Handover
< !--[if !supportLists]--> Loss of Synchronization
< !--[if !supportLists]--> Fast Fading
< !--[if !supportLists]--> Pilot Pollution / Spillover issues

< !--[if !supportLists]-->131. What is Hard Handover in UMTS? When will it
happen?
< !--[if !supportLists]--> Hard Handover in UMTS is a break before make type Handover
< !--[if !supportLists]--> It can happen in the inter RNC boundaries where there is no Iur
link.
< !--[if !supportLists]-->132. What is the typical Call Setup Time for a 3G UE
to 3G UE Call? What are the possible RF related causes for a delayed CST in this type of
call?
< !--[if !supportLists]--> 6 to 9 seconds
< !--[if !supportLists]--> Multiple RRC Attempts (UE is on poor coverage – need more
than Access Attempt)
< !--[if !supportLists]--> Delayed Page Responses
< !--[if !supportLists]--> High Load on Paging and/or Access Channel
< !--[if !supportLists]--> Paging / Access Parameters
< !--[if !supportLists]-->133. What is Soft Handover Overhead? What is the
typical value in UMTS network?
< !--[if !supportLists]--> Soft Handover Overhead is calculated in two ways. 1) Average
Active Set Size – Total Traffic / Primary Traffic. 2) Secondary / Total Traffic
< !--[if !supportLists]--> Typical Values are like 1.7 (Avg Active Set Size) or 35%
(Secondary / Total )
< !--[if !supportLists]-->134. What will happen to the Soft Handover
Overhead when you apply OCNS on the network? And Why?

< !--[if !supportLists]--> With OCNS, the interference (load) inc reases. This leads to
reduction in Ec/Io of a Pilot, which reduces the pilot spillovers. Reduction in Pilot Spillover will reduce
the Soft Handover Overhead.
< !--[if !supportLists]-->135. What are the possible causes for an Access
Failure in UMTS?
< !--[if !supportLists]--> Missing Neighbors
< !--[if !supportLists]--> Poor Coverage
< !--[if !supportLists]--> Pilot Pollution / Spillover
< !--[if !supportLists]--> Poor Cell Reselection
< !--[if !supportLists]--> Core Network Issues
< !--[if !supportLists]--> Non –availability of resources. Admission Control denies
< !--[if !supportLists]--> Hardware Issues
< !--[if !supportLists]--> Improper RACH Parameters
< !--[if !supportLists]--> External Interference
< !--[if !supportLists]-->136. (FOR ERICSSON EXPERIENCED) What is
RTWP? What is the significance of it?
< !--[if !supportLists]--> Received Total Wide-band Power
< !--[if !supportLists]--> It gives the Total Uplink Power (Interference) level received at
NodeB
< !--[if !supportLists]-->137. (FOR ERICSSON EXPERIENCED) What is the
System Reference Point at which all the Power Levels are measured in Ericsson NodeB?
< !--[if !supportLists]--> System Ref Point for E/// NodeB is at the output of TMA
(Between TMA and Antenna)

< !--[if !supportLists]-->138. What are the typical values for
‘reportingrange1a’ and ‘reportingrange1b’?
< !--[if !supportLists]--> 3 dB and 5 dB respectively.
< !--[if !supportLists]-->139. What will be the impact when you change
‘reportingrange1a’ from 3 to 4 dB and‘tim etotrigger1a’ 100 to 320 m s, with out changing
any other parameters?
< !--[if !supportLists]--> Reduction in number of Event1a
< !--[if !supportLists]--> Delayed Event1a trigger
< !--[if !supportLists]--> Reduction in Average Active Set Size
< !--[if !supportLists]--> Delay in Event1a could increase DL interference, which could
lead to a drop call or increase in Average Power Per User (reduction in cell capacity)
< !--[if !supportLists]-->140. What is Admission Control?
< !--[if !supportLists]--> Admission Control is an algorithm which controls the Resource
Allocation for a new call and additional resource allocation for an existing call. Incase, if a cell is heavily a
loaded and enough resources in terms of power, codes or CEs are not available, admission control denies
permission for the additional resource requirement.
< !--[if !supportLists]-->141. What is Congestion Control?
< !--[if !supportLists]--> Congestion Control monitors the dynamic utilization of specific
cell resources and insures that overload conditions do not occur. If overload conditions do occur,
Congestion Control will immediately restrict Admission Control from granting additional resources. In
addition, Congestion Control will attempt to resolve the congestion by either down switching, or
terminating existing users. Once the congestion is corrected, the congestion resolution actions will cease,
and Admission Control will be enabled.

< !--[if !supportLists]-->142. What is the maximum number of
Channelization Codes that can be allocated for HS, as per 3GPP standard?
< !--[if !supportLists]--> 15 codes of SF 16.
< !--[if !supportLists]--> 
< !--[if !supportLists]-->143. Wh at is‘Code Mu ltiplexing’ in HSDPA?
< !--[if !supportLists]--> Sharing the HS Channelization Codes among more than one HS
users within the 2ms TTI period.
< !--[if !supportLists]-->144. (FOR ERICSSON EXPERIENCED) In Ericsson
System, how is the Power allocated for HSDPA>
< !--[if !supportLists]--> Power unutilized by R99 PS, CS and Comman Channels, is used
for HS (PHS = Pmax - hsPowerMargin - Pnon-HS)

< !--[if !supportLists]-->145. What are Events that can trigger the HSDPA Cell
Change?
< !--[if !supportLists]--> Event 1d HS –Change of Best Cell in the Active Set
< !--[if !supportLists]--> Event 1b or Event 1c – Removal of the Best Cell from the Active
Set
< !--[if !supportLists]-->146. How is typically the Call Setup Time of a CSV call
calculated in UMTS using L3 messages?
< !--[if !supportLists]--> CST is c alc ulated as the time difference between ‘A lerting’ and
the first RRC Connection Request (Call Initiation) messages.
GSM,WCDMA,RF ,RF Optimization Interview
Objective Question
Level 2-3 NPO Questions
(RF Planning & Optimisation Engg)
In the following questions, please select one alternative which you think is the best answer
for the particular question.
Q1. SMS broadcast is done over which channel
1. SDCCH
2. BCCH
3. TCH
4. A & C
Q2. The parameter number of Slot Spread Trans (SLO)(BTS) is used to allocate a number of
CCCH blocks for .
a) Paging Channel (PCH)
b) Random Access Channel (RACH)
c) Access Grant Channel (AGCH)
d) Traffic Channel

Q3. Which of the following comment is true?
a) MAIO step is used to avoid intra-cell interference where as HSN is used to avoid inter-cell
interference
b) HSN is used to avoid intra-cell interference where as MAIO step is used to avoid inter-cell
interference
c) Both MAIO step and HSN are used to avoid intra-cell interference.
d) Both MAIO step and HSN are used to avoid inter-cell interference
Q4. Timer T200 is related with which KPI
a) SDCCH Completion rate
b) Paging success rate
c) TCH assignment success rate
d) All of the above
Q5. Which parameter defines how often paging messages are sent to MS?
a) No of Multi-frames between Paging (MFR)
b) Max No of Retransmission (RET)
c) No of Slots Spread Transmission (SLO)
d) No of Blocks for Access Grant (AG)
Q6. Which parameter is used as a margin to prevent ping-pong location updates?
a) PLMN-Permitted (PLMN)
b) Rx Level Access Minimum (RXP)
c) Cell Reselect Hysteresys (HYS)
d) Handover Margin Level (LMRG)
Q7. Which Parameter describes the minimum received field strength required by an MS to get any
service from the network in that cell in Idle mode?
a) PLMN-Permitted (PLMN)
b) Rx Level Access Minimum (RXP)
c) Cell Reselect Hysteresis (HYS)
d) Direct Access Level (DAL)
Q8. When is location updates carried out?
a) Every time an MS changes its location area under one MSC.
b) Every time an MS changes between two different MSCs
c) On a periodic basis set by a timer
d) All of the above

Q9. Increasing Radio Link Time Out (RLT) from 16 to 24 will improve following KPI
a) SDCCH Completion rate
b) TCH Completion rate
c) Paging Success rate
d) All of the above
Q10. If a cell is having TCH congestion, which of the following is true?
a) It is having TCH blocking
b) It may have TCH blocking.
c) It is having TCH Drop.
d) All of the above
Q11. Which of the parameter is set to zero for cyclic hopping?
a) BTS Hopping (HOP)
b) Hopping sequence number (HSN)
c) MAIO Offset (MAIO)
d) All of the above
Q12. What is directed retry?
a) A feature that allows a recovery system to restore a BCCH to its original TRX after fault has
been eliminated.
b) It is designed to control the traffic load of a frequency hopping radio network in which
frequencies are reused tightly.
c) It is used in call set up to assign a TCH to an MS from a cell outside the serving cell due to TCH
congestion
d) None of the above
Q13. Which of the following is measured as BER?
a) Received Signal Quality (RX QUAL)
b) Speech Quality Index (SQI)
c) Voice Quality
d) All of above
Q14. Polarization is characterized by

1. Direction of Magnetic Field
2. Direction of Electric Field
3. Direction of Electromagnetic Field
4. None of Above.
Q15 Which one is correct for TMA, TMB and Repeater?
1. Amplifies U/L, Amplifies D/L, and Amplifies both.
2. Amplifies D/L, Amplifies U/L, and Amplifies both.
3. Amplifies U/L, Amplifies D/L, and Amplifies U/L.
4. Amplifies U/L, Amplifies D/L, and Amplifies D/L.
Q16 Define Beam width of Antenna?
1. Angular distance between the points on two opposite sides of the peak direction where the
radiation intensity drops to the 1/2 of the peak intensity.
Q17 From which technique we cancel the effect of Rayleigh Fading?
1. Antenna Hoping.
2. Frequency Hoping.
3. Antenna Diversity.
4. MAIO.
Q18 If HLR=5 Million subs, VLR/HLR=0.7,mErl/Sub=30.Then how much Capacity is
required to cater the subscriber in RF for 70% utilized Network.

1. 150 K Erl
2. 300 K Erl
3. 135 K Erl
4. 165 K Erl
Q19 Electrical Tilt antenna limits coverage through?
1. Tilting of Dipoles.
2. Inserting Phase Shift.
3. Inserting attenuation.
4. None of the above.
Q20 Which Antenna has the highest front to back Ratio?
1. Loop
2. Yagi
3. Dipole
4. Parabolic
Q21 Select relation between forward power and Reflected Power if load is not connected?
1. VSWR=1
2. VSWR=∞
3. VSWR=0
4. VSWR=1/2
Q22 What is the difference between splitter and coupler?
1. Even Distribution of Power in coupler and uneven distribution in splitter.
2. Uneven Distribution of Power in coupler and even distribution in splitter.
3. Even Distribution of Power in both.
4. Uneven Distribution of Power in both.
Q23. What are mobility management states in GPRS?

1. Idle,Standby,Ready
2. Dedicated,Standby,Ready
3. Idle,Dedicated,Standby
4. None of above
Q24. Which modulation is used for EDGE above MCS-4
1. QPSK
2. GMSK
3. 8PSK
4. PSK
Q25. What does SGSN stands for?
1. Serving Gateway Support node
2. Serving GPRS Support node
3. Serving GMSC Support node
4. None of the above
Q26 In dedicated mode, SMS comes on which channel?
a) SDCCH.
b) SACCH.
c) FACCH.
d) None of the above.
Q27 In Dedicated Mode, MS receives which system info. Messages?
1. System Info 1, 2, 3.
2. System Info 1, 2, 3,4,13.
3. System Info 5, 6.
Q28 Freq used in Uplink of Satellite communication is higher while in GSM it is lower. Why?
1. Loss α freq.

2. Loss α 1/freq.
3. Loss α sqr(freq)
Q29 AMR is used to improve?
1. SQI
2. Downlink quality.
3. Uplink Quality
4. None of the Above.
Q30 In Idle Mode, MS receives which system info. Messages?
a) System Info 1, 2,3.
b) System Info 1, 2, 3,4,13.
3. System Info 5, 6.
d) None of the above
Q31 The Common Control channel multiframe consists of?
1. 51 time slots.
2. 50 timeslots
3. 4 Time slots
4. 9 Time slots
Q32 Which of the following are true?
1. Type 1 Paging: can address up to 2 mobiles using either IMSI or TMSI.
2. Type 2 Paging: can address up to 3 mobiles, one by IMSI and the other 2 by TMSI.
3. Type 3 Paging: can address up to 4 mobiles using the TMSI only.
4. All of the above.
Q33 In GSM while performing handover
1. The MS breaks connection from source cell and then tunes on the target cell.

2. The MS continues connection from the source, tunes on the target and then releases
the source cell.
3. MS gets paging message from the target and replies it on its RACH and gets TCH
allocated.
4. MS gets paging message from the target and replies it on its RACH and gets
SDCCH allocated.
Q34 If E-RACH is used then which of the following is true?
1. GSM range will increase beyond 35Km
2. It will increase no of RACH channels and release congestion on RACH.
3. SDCCH assignment will improve.
4. All above are false.
Q35 In dedicated mode the BTS receives handover command on?
1. TCH
2. SDCCH
3. SACCH
4. FACCH
Q36 The duration of a single timeslot is?
1. 4.615 ms
2. 1250 ms
3. 0.577 ms
4. 156.25 ms
Q37 Modulation used in GSM radio interface is?
1. Phase shift keying (PSK)
2. Gaussian Minimum shift Keying (GMSK)
3. Frequency modulation.
4. 8PSK.
Q38 TIE stands for?

1. Terminal Equipment identifier
2. Transcoder Input Erlang
3. TRX identifier for Edge TRX
Q39 As per GSM Standard in case of frequency hopping the C/I value should be at least?
1. 3 dB
2. 6 dB
3. 9 dB
4. 12 dB
Q40 In inter BSC handover the handover is controlled by?
1. GMSC
2. MSC
3. Source BSC
4. Target BSC
Q41 The maximum no of neighbors that can be defined with a cell is?
1. 8
2. 16
3. 32
4. 64
Q42 The permissible value of VSWR for feeder cable is?
1. < 1.3
2. >1.3
3. > 1
4. <2

Q43 The function of Transcoder is
1. To convert 64 kbps speech channel on A interface to 16 kbps speech channel on A-ter
Interface and vice versa.
2. To convert 16 kbps speech channel on A interface to 64 kbps speech channel on A-ter
Interface and vice versa.
3. To convert analogue speech signal from MSC to Digital signal for use of BSC
4. To convert analogue speech signal from BSC to Digital signal for use of MSC
Q44 TSC stands for
1. Time Synchronized Channel
2. Temporary subscriber code
3. Transcoder Signaling Controller
4. Training Sequence Code
Q45 If Cell bar is set to “yes” on a cell then
1. It will reject new calls as well as handover calls
2. It will reject new call assignment but will receive calls by Handover
3. It will reject Handover but allow new call to come
4. The BTS will go into locked state.
Q46 DAP stands for
1. Dual Abis pool
2. Dynamic Allocation protocol
3. Dynamic Abis Pool
Q47 Who can initiate the GPRS detach
1. The MS only
2. The SGSN only
3. Both the MS and the SGSN

Q48 The mapping of logical name/Host name to IP addresses in the GPRS network is done
by
1. Border Gateway
2. SGSN
3. GGSN
4. DNS
Q49 Where is the mobility management context established in GPRS
1. In the MSC
2. In the SGSN
3. In the GGSN
4. All of the above
Q50 Which layer uses the functionality of Uplink State Flag (USF)?
1. RLC Layer
2. Physical Layer
3. MAC Layer
4. All of the above
Q51 How many TDMA frames are there in a PDCH multiframe?
1. 51
2. 52
3. 26
4. 8
Q52 Which coding scheme does not use Forward Error Correction (FEC)?
1. CS-1
2. CS-2
3. CS-3
4. CS-4

Q53 Which new area is defined in GPRS compared to GSM?
1. Location Area
2. Routing Area
3. Both a and b
Q54 Which layer is responsible for segmentation and reassembly of LLC PDUs and
backward error correction (BEC) procedures?
1. Physical Layer
2. Application Layer
3. RLC Layer
4. MAC Layer
Q55 Which coding scheme has adopted the same coding as used for SDCCH?
1. CS-1
2. CS-2
3. CS-3
4. CS-4
Q56 What is the single timeslot data rate for coding scheme CS-2
1. 7.8 Kbit/s
2. 10.4 Kbit/s
3. 13.4 Kbit/s
4. 21.4 Kbit/s
Q57. Combiner works in
a) Downlink direction
b) Uplink direction
c) In both direction

d) As a Amplifier
Q58 Number of AMR codec modes used only in FR?
1. 6
2. 4
3. 2
4. 8
Q59 During conference call which channel is used to establish another call-
1. SACCH
2. SDCCH
3. FACCH
4. TCH
Q60 What is Duplex spacing.
1. Difference between first frequency of Uplink and last frequency of Downlink.
2. Difference between first frequency of Downlink and first frequency of Uplink.
3. Difference between last frequency of Downlink and first frequency of Uplink.
Q61 What does MSRN stands for ….
1. Mobile Station Registration Number
2. Mobile System Registration Number
3. Mobile Station Roaming Number
4. Mobile Station Register Number.
Q62. If my MCC=404, MNC=05, LAC=100, CI = 14011, then what will be CGI for same??
1. 4040510014011

2. 404056436BB
3. 4040514433273
4. 4040510033273
Q63. Which information is there in Handover Access Command in Layer 3 Message?
1. BCCH & BSIC of Source
2. BCCH & BSIC of Target
3. Handover Reference Value
4. All of above.
Q64 What is the use of Immediate Assignment Extended Command?
1. Allocate AGCH for 2 Mobiles
2. Allocate SDCCH for 3 Mobiles
3. Allocate SDCCH for Call and SMS simultaneously.
4. None of Above.
Q65. What is the cause value for normal call release?
1. 16
2. 3
3. 14
4. 45
Q66. Location Update Request falls under which management system?
1. RRM
2. CM
3. CRM
4. MM
Q67. Which system information message contains NCC Permitted Values?
1. SI 6
2. SI 2
3. All of Above.

4. None of Above.
Q68. When timer T3212 expires which process is initiated?
1. Cell Update
2. RAC Update
3. LAC Update
4. Handover
Q69. If AMR FR & AMR HR is enabled in network, then what will be the formula for counting
GSM FR Traffic with help of EOSFLX KPI Reports ?
1. Total Traffic – AMR FR Traffic
2. Total Traffic – AMR FR Traffic - AMR HR Traffic
3. Total Traffic – GSM HR Traffic – AMR FR Traffic – AMR HR Traffic
4. None of Above.
Q70. By reducing value of RET parameter it will help to improve which KPI?
1. TCH Drop
2. SDCCH Drop
3. HO Success
4. None of above.
Q71. What is the range of AMH TRHO PBGT Margin parameter?
1. -6 to +6, 255
2. -24 to +24, 255
3. -6 to +24, 255
4. +6 to +24, 255
Q72. What is the relation between HO Load Factor and HO Priority Level?
1. Load Factor > Priority Level
2. Load Factor >= Priority Level
3. Load factor < Priority Level
4. Load Factor <=Priority Level

Q73. Which are the basic features helps to distribute traffic in nearby cells?
1. DR
2. IDR
3. AMH
4. All of above
Q74. Using Multi BCF Common BCCH feature operator can expand how many numbers of
TRX in one segment without using another BCCH?
1. 16
2. 24
3. 30
4. 36
Q75. While Using Path loss Criterion C2 which parameter should be made “0” so that this
particular cell have higher C2 Value even though having poor C1?
1. CRO
2. TEO
3. Penalty Time
4. None of above.
Q76. Common BCCH feature is implemented in network, then which feature will help to
access the secondary freq. spectrum directly?
1. DR
2. DADB
3. DADL
4. All of above
Q77. Which types of GSM Reports are generated by Nemo Analyzer?

1. GSM Performance Report
2. GSM Benchmark Report
3. All of above
4. None of above
Q78. What is the range of parameter PMRG?
1. -24to +63
2. -24 to +24
3. -63 to +63
4. 0 to +63
Q79. How many maximum uplink TBF can be there per RTSL?
1. 6
2. 7
3. 8
4. 9
Q80. What should be minimum value of CDED (%) to have 1 RTSL as dedicated GPRS
Timeslot considering 2 TRX as GPRS TRX?
1. 0
2. 1
3. 8
4. 10
Q81. What does TRP Value = 3 means?
1. TCH allocation from BCCH TRX for non-amr user and from beyond BCCH TRX for
amr USER
2. TCH allocation from beyond BCCH TRX for non-amr user and from BCCH TRX for
amr USER
3. All of above
4. None of Above
Q82. How many basic EGPRS MCS Families are there?
1. 1
2. 2

3. 3
4. 4
Q83. Which is / are the main factors affecting the Radio Accessibility for TBF in UL/ DL?
1. Coverage
2. Capacity
3. Interference
4. All of above.
Q84. Which parameter setting can help to increase the TBF Retainability?
1. UL Power Control
2. DL Power Control
3. All of above.
4. None of above.
Q85. What should be SDCCH GOS when compared to TCH GOS?
1. SD GOS = TCH GOSDTX
2. SD GOS = 1/2(TCH GOS)
3. SD GOS = 1/4(TCH GOS)
4. SD GOS = 2(TCH GOS)
Q86. Which feature/technique is not used to reduce blocking / congestion?
1. Directed Retry
2. Traffic Reason Handover
3. Dynamic SDCCH
4. Intra Cell Handover
Q87. Rx Quality = 3 means BER =?
1. 0.2 - 0.4
2. 6.4 - 12.8
3. 1.6 - 3.2
4. 0.8 - 1.6

Q88. Following is false when using Dynamic SDCCH.
1. SDCCH Handover cannot be used.
2. Free TCH is used when SDCCH is required.
3. SDCCH carrying CBCH cannot be used.
4. Every SDCCH request can be fulfilled by Dynamic SDCCH.
Q89. In Link Budget; what has the least importance?
1. GSM Antenna Gain
2. Path Loss
3. Feeder Loss
4. MS Antenna Gain
Q90. When 2 calls are made from different TRXs of same cell having 1*1 RF hopping; what
plays important role to neglect C/I?
1. MAL ID
2. HSN
3. MAIO Step
4. MAIO Offset
Q91. Frame loss can be reduced by:
1. Speech Coding
2. Channel Coding
3. Interleaving
4. Burst Formatting
Q92. What can be done to overcome combiner loss when cell is upgraded from 2 TRX to 3
TRX?
1. Remove Combiner
2. Air-Combining
3. HOP = OFF
4. TMA Implementation
Q93. What is the Basic feature amongst below:
1. SAIC

2. STIRC
3. AMR Progressive Power Control
4. Freq. Hopping
Q94. Out of following channels which one is common channel?
1. AGCH
2. SACCH
3. TCH-FR
4. FACCH
Q95. Out of following channels which one is the answer to RACH?
1. SDCCH
2. AGCH
3. FACCH
4. SACCH
Q96. In Air-interface TDMA time-slot means how many Seconds?
1. 576.9us
2. 4.615ms
3. 6.12sec
4. 480ms
Q97. Which type of antenna is used in MS?
1. Dipole
2. Omni
3. Loop
4. Cross-polar
Q98. Choose the correct Erlang Formula?
1. x Erlang= (calls per hour) * (average call duration)/3600 Sec
2. x Erlang= (no. of user)*(3600 sec)/ (calls per hour)
3. x Erlang= (no. of calls)*(no. of user)/ (average call duration)
4. x Erlang= (calls per hour)*(no. of users)/3600 sec
Q99. If GOS of an N/W is 3%, what does it mean?
1. 3 out of 100 calls may fails

2. average call duration is 3min
3. at a time 3% of total users can make a call
4. 3% blocking in the N/W is permitted
Q100. Which type of message is "Identity Request”?
1. Mobility Management
2. Radio Resource Management
3. Call Control
4. Call related SS message
Q101. Paging message type 2 contains.
1. Paging message for 3 mobiles
4. Paging message for >4 mobiles
Q102. Out of following which one is not a part of NSS?
1. Mobility Management
2. Connection Management
3. Radio Resource Management
4. Charging
Q103. In L3 messages, out of following Info messages which one carries Dedicated Mode
Information?
1. System Info 2
2. System Info 4
3. System Info 5
4. System Info 13
Q104. Which one out of following is not a part of AMR Codec Modes?
1. 4.6
2. 5.9
3. 7.4
4. 12.2

Q105. Frequency Hopping…
1. Eliminates the problem of fading dips
2. Eliminates the problem of ISI
3. is part of channel coding
4. spreads the problem of fading dips to many mobile stations
Q106. ISI is caused by:
1. fading dips
2. the Viterbi equalizer
3. reflection
4. interleaving
Q107. Maximum data throughput / tsl possible incase of GPRS is: X`
1. 18.8kbps
2. 27.2kbps
3. 29.2kbps
4. 21.4kbps
Q108. Out of following which element/s in the GSM N/W can not initiate HO?
1. BSC
2. BTS
3. MSC
4. None of Above
Q109. Out of following, which type of antenna has highest directivity?
1. Dipole
2. Helical
3. Log-Periodic
4. Yaagi-Uda
Q110. When we say the output power of a Transmitter is 30dBm, how many watts does it
mean?
1. 3W
2. 1W
3. 1mW

4. 30mW
Q111. Out of following which one is a passive device?
1. Repeater
2. Cross Polar Antenna
3. TMA (Tower Mount Amplifier)
4. TRX
Q112. Out of following which can not be observed during Drive-test?
1. Rx Quality
2. Location Update
3. Paging Load
4. GPRS Attach
Q113. If a cell is EDGE capable, how much Downlink Throughput can we guarantee to
customer?
1. 59.2kbps
2. 473.6kbps
3. 236.8kbps
4. can't guarantee
Q114. How many blocks of AGCH are reserved in non combined mode?
1. 1-7
2. 0-2
3. 0-7
4. None of Above.
Q115. What are the contents of authentication triplets?
1. A3,A5,A8
2. SRES,RAND,Kc
3. RAND,A3,A8
4. SRES,Kc,A8

Q116 Frequency hopping in a network:
1. May or may not be implemented
2. Does not provide optimal gain if the hopping frequencies are less than 4
3. Both above are correct.
Q117 .Which of the following functions is not done by SDCCH CHANNEL:
1. Authentication
2. Transmission of short messages
3. Adaptive power control information from BTS to MS only
4. Assignment of traffic channel to MS.
Q118 How many TS can be used at the most with HSCSD?
1. 2
2. 4
3. 6
4. 8
Q119 What should be the value of C/I when you are in hopping mode?
1. Above 9
2. Above 12
3. Less than 9
4. All of the above are correct
Q120 Which value of level and quality should be considered for analysis in a DT log
1. Full
2. Sub
3. Both
4. None of the above is correct.
Q121 What are the coding schemes observerd in UL/ DL after implementing EDGE in your
Network:

1. CS1-CS4
2. MCS1-MCS6
3. MCS5-MCS9
4. MCS1-MCS9
Q122 What does DAP stand for?
1. Dynamic Abis Pool
2. Dynamic Access Pool
3. Dynamic Access Protocol
Q123 How many codec’s can be defined for AMR HR
1. 5
2. 2
3. 6
4. 4
Q124 How many TRX’s can be accommodated max on a single E1 where DAP pool is
assigned for 4 TS in a Ultra site
1. 12
2. 16
3. 18
4. 24
Q125 How much traffic will be offered by a sector having 4 TRX with GOS of 2%
1. 24Erlangs
2. 21.03Erlangs
3. 23.56Erlangs
4. 22.12 Erlangs

Q126 Which ND report would you refer in order to find the discrepancy for Handovers?
1. Report 163
2. Report 166
3. Report 153
4. Report 208
Q127 On what basis would an optimizer decide whether the site serving is overshooting:
1. On the basis of TA
2. From ND report 232
3. Physically verifying whether the cell is having up tilt
4. All of the above
Q128 BBH is generally implemented where:
1. For dense network
2. For small capacity network
3. For cells where tight frequency reuse is required
Q129 In case of Directed retry HO:
1. HO is performed from TCH of serving to TCH of Adjacent cell
2. HO is performed from SDCCH of serving to TCH of adjacent cell
3. HO is performed from TCH of Serving to SDCCH of adjacent cell
4. HO is performed from SDCCH of serving to SDCCH of adjacent cell
Q130 Which alarm indicates the TRX faulty operation in the system:
1. 7601
2. 7602
3. 7725
4. 7745

Q131 C/I estimation during a DT can be done in:
1. U/L
2. D/L
3. Both A&B
4. Cannot be estimated.
Q132 Which is the unique feature in TEMS for analsing speech quality:
1. Rx qual Full
2. Rx Qual Sub
3. SQI
4. Rx Qual.
Q133 Drop calls due to Handovers can be caused basically due to:
1. Neighbors with Co-BSIC
2. Neighbor with Co-BCCH
3. Neighbors with Co-BCCH and Co-BSIC
4. All of the above.
Q134 Consider a cell where the no calls are happening, the probable causes would be
1. Wrong definition of LAC,CI
2. DMAX=0
3. Only A is correct
4. Both A&B are correct.
Q135 What should be the value of Rxlev Access min set:
1. -47dbm
2. -110dm
3. -65dbm
4. -85dbm

Q136 What would be the output of a cell with parameter setting as
MstxPwrmax=0db,BsTxPWrMax =30db
1. Cell will carry max.no of calls
2. Cell will carry very few calls
3. Cell will not be latched
4. Cell with a correct parameter setting.
Q137 What would be the power loss after using a combiner in a sector:
1. -2db
2. -1db
3. -3db
4. -4db
Q138 What will happen in case where GTRX=Y(Non Edge TRX),EDGE=Y:
1. TRX will be unlocked
2. System will not allow the TRX to be unlock
3. TRX will go in Block state
4. Both B&C are correct.
Q139 Which report would give you the total payload for GPRS:
1. 232
2. 208
3. 228
4. 226.
Q140 In a Flexi BTS 1 physical TRX would logically represent how many Trx:
1. 1

2. 2
3. 3
Q141 ‘Booster ’ becomes a solution in case of :
1. Capacity
2. Coverage
3. A & B Both
Q142 Recommended value of ITCF is :
1. 2
2. 0
3. 1
4. 4
Q143. Which ND report gives the data for RACH rejection on cell level?
5. 134
6. 132
7. 188
8. 111.
Q144. Which ND report would you refer in order to find the discrepancy for Handovers?
5. Report 163
6. Report 166
7. Report 153
8. Report 208
Q145.On what basis would an optimizer decide whether the site serving is overshooting:
5. On the basis of TA
6. From ND report 232
7. Drive test logs
8. All of the above

Q146.Which ND report would give you the total payload for GPRS:
5. 232
6. 208
7. 228
8. 226.
Q147 What is a Command to check active alarms on bts:
1. ZERO
2. ZEQO
3. ZEOL
4. ZELO
Q148 Value of BSC Timers can be checked by command:
1. ZEFO
2. ZEDO
3. ZEHO
4. ZEGO
Q149 ND Report 71 Tells:
1. Adjacencies having highest success rate
2. Adjacencies having highest failure rate
3. All adjacencies
Q150.Which report gives value of dedicated data time slots:
1. 051
2. 053
3. 061
4. 063.

Q151. Which is ND Report number for AMR Parameters?
1. 051
2. 111
3. 216
4. 053
Q152. Which report shows percentage of HO attempts happening due to GPRS?
1. 150
2. 151
3. 153
4. 154
Q153 Which ND report gives detailed analysis of a cell?
1. 204
2. 216
3. 186
4. 226
Q154 In which ND report we can see hourly Traffic Profile for a cell?
1. 180
2. 181
3. 182
4. 186
Q155. In which ND report we can see hourly call drops due to TCH_RF_NEW_HO counter?
1. 216
2. 213
3. 163
4. 166
Q156. In which ND report we can see adjacency discrepancy between neighbor definitions?

1. 061
2. 060
3. 067
4. 073
Q157. Which are the Coverage Enhancement Features of NSN System?
1. ICE
2. Reverse ICE
3. Smart Radio Concept(SRC)
4. All of Above
Q158. Which ND Report shows Paging Success Rate per LA?
1. 213
2. 216
3. 186
4. 222
Q159. Which ND report shows EGPRS KPI?
1. 230
2. 226
3. 229
4. 228
Q160 Which counter shows DL multislot assignment in percentage?
1. msl_13
2. msl_14
3. msl_15a
4. msl_16a
Q161. How many 64 Kbps DAP TSLs are required if MS is using MCS 9 (consider:
dedicated data timeslot = 4, single data user attached)?
1. 2
2. 4
3. 6
4. 8

Q162. How many maximum Abis timeslots can be handle by PCU ?
1. 64
2. 128
3. 256
4. 264
Q163. What is the Maximum output power of Metrosite BTS in terms of Watt?
1. 5
2. 10
3. 20
4. 40
Q164. What is the maximum number of TRX’s can created per BCSU in BSC 3i with version
S12?
1. 110
2. 200
3. 100
4. 220
Q165. Which interface is required to implement combine paging (Voice + Data)
1. Gs
2. DPM ( Dual Paging Mode)
3. Gn
4. DPT ( Dual Paging Transmission)
Q166. In which ND report we can see TRHO Handovers attempt and success?
1. 153
2. 154
3. 155
4. 156

Q167. How many TRX’s can be handled by 1 BB2F Card in Ultra Site BTS?
1. 2
2. 3
3. 4
4. 6
Q168. Which of the following BTS Type do not have combiner in-built in them?
1. Ultra Site
2. Metro Site
3. Flexi BTS
4. None of above
Q169. Which report will help to see EDAP Congestion?
1. 280
2. 281
3. 128
4. 082
Q170. In which ND report we can see paging deletion counts for cell level?
1. 180
2. 181
3. 182
4. 186
Q171 Out of following, which is true as per NSN Specification?
1. CDED<=CDEF
2. CDED>CDEF
3. CDED=CDEF+CMAX
4. CDEF=CDED+CMAX
Q172. What should be minimum value of CDED(%) to have 1 RTSL as dedicated GPRS
Timeslot considering 2 TRX as GPRS TRX?
1. 0

2. 1
3. 8
4. 10
Q173 Which report shows Intra Cell Handover Statistics?
1. 150
2. 153
3. 154
4. 158
Q174 What is the maximum data throughput/timeslot can be achieved in case of MCS 9?
1. 64 Kbps
2. 59.2 Kbps
3. 118 Kbps
4. 230.4 Kbps
Q175 Which BTS Type does not support Rx Diversity (RDIV) parameter?
1. Flexi Edge BTS
2. Ultra BTS
3. Metro BTS
4. Talk Family BTS
Q176 In case of EDGE which of the following CS offers highest coverage?
1. MCS 1
2. MCS 9
3. MCS 5
4. CS 1
Q177 Which ND Report shows Trx vise quality distribution?
1. 180
2. 269
3. 196
4. 169
Q178 ND Report gives radio timeslot configuration?

1. 111
2. 222
3. 121
4. 051
Q179 Noise separation feature can be implemented in?
1. TCSM
2. BSC 3i
3. Flexi BTS
4. TRX
Q180 Which of the following is not a feature of GSM network alone, but also feature of
analog mobile communication network?
1. Digital transmission of user data in air interface
2. Possibility of full international roaming in any country
3. Better speech quality
4. Fully digitized switching exchange
Q181 which of the following is parameter affecting cell sites while planning the network
1. Antenna height
2. MS power
3. BTS Power
4. None Of Above
Q182 What is E interface?
1. MSC-MSC
2. MSC-VLR
3. MSC-HLR
4. HLR-VLR
Q183 In GSM which type of handover occurs?
1. Hard
2. Soft
3. Both of the above
4. Make before break

Q184 Choose the correct bit pattern of a flag in LAP-D format ?
1. 01111110
2. 11111111
3. 10101010.
4. 01010101.
Q185 Mobile identity is a part of?
1. Physical layer Info
2. Lap-D Info
3. BSSMAP Info
4. GSM L3 Info
Q186 Maximum PLMN Permitted can be ?
a) 7
b) 8
c) 1
d) 2
Q187 how many BSIC possible if NCC=4, no of BCCH ARFCN =8 ?
a) 32
b) 64
c) 256
d) 1024
Q188 DTX helps in
a) Reducing TCH congestion
b) Reducing SDCCH congestion
c) Reducing interference
d) Improving paging success
Q189. BSSAP needs the services of SCCP to
a) Analyze A subscriber data
b) To perform Connectionless signaling with the MSC
c) Send MAP messages to HLR via the MSC

Interview question for 2g,3g,4g

Interview question for 2g,3g,4g

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Andere mochten auch

Andere mochten auch (20)

Ähnlich wie Interview question for 2g,3g,4g

Ähnlich wie Interview question for 2g,3g,4g (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Interview question for 2g,3g,4g