please post UMTS interview questions

[jamal]

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]

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]

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]

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]

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