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coursekec
2010-07-21, 11:39 AM
Please post UMTS questions that are likely to be asked in an interview along with the answers if possible ?

thanks in advance..

mike
2010-07-21, 12:15 PM
some questions about WCDMA:L. I don´t have the answer. Only for UMTS interview example.

1 what is meaning of Ec/Io? what is the best value of Ec/Io when there is 75% of downlink load simulated, while the PCPICH power is 33dBm (total power of the cell is 43dBm).


2 how to find missing neighbor cell list during the drive test?

3 what is the relationship between "singaling flow", "counter" and "KPI"?

4. what should be the normal value range of RTWP, assume there is no any interference and any user.

5why we need the antenna isolation? how to calculate the anatenna isolation distance?

6.what is the relationship between link budget and simulation?

eg7014
2010-07-21, 01:16 PM
What is the main difference between RB (Radio Bearer) and RAB (Radio Access Bearer)?

firstmaxim
2010-07-21, 02:34 PM
Here are some more to Mike's questions:

- Differentiate between the uplink and downlink modulation techniques used in UMTS.
- What is the range of spreading factors used in the uplink and downlink?
- Differentiate between channelization and scrambling codes.
- What is softhandover? How does it impact performance and network capacity?
- What is compressed mode operation? How does it impact cell capacity?

coursekec
2010-07-22, 01:17 AM
Thanks to all for the questions..But can you provide answers to these questions ?
Differentiate between channelization and scrambling codes?

- Differentiate between the uplink and downlink modulation techniques used in UMTS.
- What is the range of spreading factors used in the uplink and downlink?

firstmaxim
2010-07-22, 12:06 PM
Thanks to all for the questions..But can you provide answers to these questions ?
Differentiate between channelization and scrambling codes?

- Differentiate between the uplink and downlink modulation techniques used in UMTS.
- What is the range of spreading factors used in the uplink and downlink?
channelization vs. scrambling codes:
The former spreads the signal; has good cross correlation properties; orthogonal to one another, variable code
The latter does not spread the signal; has good auto-correlation properties; almost orthogonal to one another; not variable in size.

Uplink vs. Downlink modulation:
Downlink uses QPSK
Uplink uses Dual BPSK (biomedical compatibility reasons)

Range of Spreading Factors:
Downlink : 4 to 512
Uplink: 4 to 256

Hope it helps.

senjamir
2010-07-22, 03:36 PM
Please post UMTS questions that are likely to be asked in an interview along with the answers if possible ?

thanks in advance..

Hi,

Below are the questions given to me during my interview.


1. Protocol Messages between network elements
WBTS and RNC – NBAP
RNC and RNC – RNSAP
RNC and MSC – RANAP
RNC and SGSN – RANAP

2. Signaling Protocol Message between UE and RNC
RRC

3. Factors that affect HSDPA bit rate. Explain relationship
A. Modulation
B. Channel Quality
C. Number of Codes

4. Causes of HO
Just explain the events

5. What is the value for soft handover overhead
I told him that some design are 30% some are 40%

These are the things that i remember back then. :)

Hope this might help.

Br,

Sen

coursekec
2010-07-23, 12:08 PM
thanks a lot to both of you..
i've added reputation to both of you..

simmus0300
2010-07-27, 11:46 AM
pl give the anwsers of thses questions.

simmus0300
2010-07-27, 11:18 PM
Who will give answers to these questions ? pl give.


some questions about WCDMA:L. I don´t have the answer. Only for UMTS interview example.

1 what is meaning of Ec/Io? what is the best value of Ec/Io when there is 75% of downlink load simulated, while the PCPICH power is 33dBm (total power of the cell is 43dBm).


2 how to find missing neighbor cell list during the drive test?

3 what is the relationship between "singaling flow", "counter" and "KPI"?

4. what should be the normal value range of RTWP, assume there is no any interference and any user.

5why we need the antenna isolation? how to calculate the anatenna isolation distance?

6.what is the relationship between link budget and simulation?

jamal
2010-08-02, 03:10 PM
What is the main difference between RB (Radio Bearer) and RAB (Radio Access Bearer)?

CMIIW,

The connection segment. RB connection segment between UE until RNC, just radio part. While, RAB handle connection segment from UE to Core Network.

C U @ Top
//JM

yoronjo
2010-09-07, 10:29 AM
Here are the optimization questions that were asked from me during an interview.

1. What does 'too many servers' mean?
2. what is pilot pollution
3. soft handover vs softer handover
4. what is the length of 1 radio frequency channel in wcdma
5. what is the e******* rssi range
6. what is the formula/calculation for the Ec/Io
7. what is the king of all channels in WCDMA and why?
8. mechanical DT vs electrical DT
9. which do you do first, mech DT, elec DT, or power adjustment?
10. E******* threshold for RTWP delta for p6

sonerss
2010-09-07, 03:11 PM
Here are the optimization questions that were asked from me during an interview.

1. What does 'too many servers' mean?
2. what is pilot pollution
3. soft handover vs softer handover
4. what is the length of 1 radio frequency channel in wcdma
5. what is the e******* rssi range
6. what is the formula/calculation for the Ec/Io
7. what is the king of all channels in WCDMA and why?
8. mechanical DT vs electrical DT
9. which do you do first, mech DT, elec DT, or power adjustment?
10. E******* threshold for RTWP delta for p6

Hi

Can you give us the answers yoronjo.

Thanks

wastedwardy
2010-09-18, 06:33 AM
These are off the top of my head :

2. what is pilot pollution - more pilots than the number of fingers in the rake receiver (normally 4)

3. soft handover vs softer handover - Soft handover: Between sectors on different site, Softer handover between sectors on the same site

4. what is the length of 1 radio frequency channel in wcdma - 3.84MHz

8. mechanical DT vs electrical DT - Mech Tilt is the physical tilt of the antenna, Elect tilt is the effect of phase alignment of the elements in an antenna to produce the effect of downtilt

9. which do you do first, mech DT, elec DT, or power adjustment? Elect, then Mech then Power.
Elect Tilt has the bonus effect of tilting the front and back lobes, mech downtilt will uptilt the backlobe, power reduction will reduce overshooting but will reduce in building penetration

sadok
2011-03-04, 02:21 PM
2 how to find missing neighbor cell list during the drive test?
- Call will drop due to bad covergae then UE will camp into another cell with good RSCP & EcNo
- You can find the missing neighbors as DN detected neighbors
- You can see in the scanner a good cell but UE will not make a SHO to that cell and keep connected to other cell.

3 what is the relationship between "singaling flow", "counter" and "KPI"?
- KPIs is calculated based on counters
- Counters are triggered point are based on signalling it means counters can be triggered once one message is received or because a timer expired due one message does not received.

4. what should be the normal value range of RTWP, assume there is no any interference and any user.
- RTWP -104 up to -109 dBm depend on the NodeB types and vendors

5why we need the antenna isolation? how to calculate the anatenna isolation distance?

- Antenna isolation is recommended to avoid IM Inter modulation different systems


- Is calculated based on the antenna gain and the output power from different antennas located on the same area

6.what is the relationship between link budget and simulation?
- Link budget is used to calculate cell radius based on coverage, and simulation simulate the load and the interference.... in that radius