3G Optimization Interview Topics

1. Important parts of Benchmarking Report

a. RSCP Coverage

b. Ec/Io Coverage

c. CSSR

d. DCR

e. Retainability

f. Handover (Mobility)

g. Call Setup Time

h. ASU Type

i. 3G-2G Serving percentage

j. IRAT Handover

k. BLER and Quality statistics

2. UMTS Channels

a. CPICH

b. SCH

c. AICH

d. BCH BCCH

e. FACH CCCH

f. RACH CCCH

g. DCH DCCH

3. HSDPA Channels

a. HS-DPCCH (uplink signaling)

b. HS-SCCH (downlink signaling)

c. HS-PDSCH or HS-DSCH (data channel)

4. HSUPA Channels

a. E-DPDCH

b. E-DPCCH

c. E-DCH

d. E-AGCH

e. E-RGCH

f. E-HICH

5. Dropped Call Types

a. Missing Neighbor

b. Poor Coverage

c. Pilot Pollution

d. Congestion

e. Not Radio Reasons

f. Equipment Fault

6. Blocked Call Types

a. Security and Authentication Mode Failure

b. UE Issues

c. Disconnect on RAB Setup

d. Unavailable Resource

e. UE Sensitivity Fault

f. Unanswered RRC requests

g. Barred Network

7. Major Network Problems

a. Poor Coverage

b. Poor Cell Dominance

c. Pilot Pollution

d. Missing Neighbors

e. Corner Effects

8. Important Events in PS Call

a. Attach and Detach

b. PDP Context Activation

c. Download and Upload

d. Dual Mode

9. HSDPA Categoriesa. 3.6 Mbps Cat 5 & 6 (5 HS-DSCH Codes)

b. 7.2 Mbps Cat 8 (10 HS-DSCH Codes)

c. 14.4 Mbps Cat 10 (15 HS-DSCH Codes)

d. 21.1 Mbps Cat 14 (15 HS-DSCH Codes, MIMO and 64 QAM)

10. Number of CE for PS 384 = 10

11. Number of Users for PS 384 = 3

12. HSDPA Factors

a. Number of HSDPA Codes

b. Number of HS-SCCH Codes

c. Max HS-PDSCH Codes per Users

d. Algorithm and Scheduling

e. Number of HARQ Process

13. HSDPA Parameters

a. HS-SCCH Power Offset

b. Measurement Power Offset

c. CQI Feedback Cycle, Power Offset

d. ACK-NACK Power Offset

e. Number of HARQ Process

f. MAC-hs window size

g. Tx- Rx Window size

14. HSUPA Parameters

a. E-DPCCH to DPCCH Power Offset

b. Happy Bit delay

c. E-TFCI Power offset

d. E-AGCH Channelization Code

e. E-AGCH Power Offset

15. Reasons of Low Throughput in HSDPA:

a. Poor RF Conditions (Low CQI)

b. Frequent Serving Cell Change (Low CQI)c. Signaling Delay

d. E1d setting issues

e. TCP segment loss outside air interface

f. TCP Tx/Rx window setting

g. Iub Flow Control

h. FTP server issues

16. HSDPA Scheduler Type

a. Max C/I

b. Round Robin

c. Proportional Fair(mostly used)

17. Timers and Counters

a. T300, N300 (2sec)

RRC Connection Retransmission

b. T312, N312(1 sec)

In Sync establishment

c. T313, N313(5 sec)

Out of Sync Failure

d. T314

(12 sec)Cell Update (CS)

e. T315

(180 sec)Cell Update (PS)

f. T302, N302(1.2 sec)Cell Update Confirm

18. Resources for Each Call Type

a. AMR

SF 128

CE 1 (UL)1(DL)b. VP

SF 32

CE3 (UL)2 (DL)

c. PS 128

SF 16

CE5 (UL)4 (DL)

d. PS 384

SF 8

CE 10 (UL)8 (DL)

19. Event Thresholds

a. E1a3dB

b. E1b6dB

c. E2d-12dBand -101 dBm

d. E2f-10dBand -99dBm

20. NASTARa. Network performance and monitoring tool

b. SQL Based

c. Collect data from M2000

d. Data storage up to 3 months

e. Supports 5 RNC and 6000 Cells

21. NASTAR Inputs:

a. RNC performance data

M2000 / BAM

b. Project Parameters

Manual

c. Configuration ParametersM2000

d. CHR Data

M2000 / BAM

e. Interference data

M2000 / BAM

f. Coverage Data

LMT client

g. NodeB performance dataM2000

22. NASTAR Analysis:

a. Performance Analysis

b. Neighbor Cell Analysis

c. Call Drop Analysis

d. Pilot Pollution Analysis

e. Interference Analysis

f. Resource Monitoring

i. CPU Utilization

ii. Iub Utilization

iii. Traffic Load

iv. Cell Load

23. Monitoring Levels

a. Level 1 Statistics, Alarm Logs(M2000)

b. Level 2 Sample tracing, CHR(M2000 and NASTAR)

c. Level 3 DT Data, Single UE Tracing

24. NASTAR Performance Data:

a. RAN Counters

(KPI)

b. Call History Records

(CHR)

CDR Analysis

c. System History Records

(SHR)

Cell Status

d. Real-Time User Monitor

(RUM)

IMSI Tracing

e. Real-Time System Monitor(RSM)

Load, Inference, etc

25. NASTAR Counters:

a. For calculating Call Drop Rate

b. For calculating Handover Success Rate

26. LMT Trace Message Levels:

a. To or From NodeB

NBAP

b. To or From CN

RANAP

c. To or From UE

RRC

27. Throughput Types in Actix

a. Payload L1

with CRC blocks

b. Throughput L1

without CRC blocks

c. PDU throughput

MAC/RLC Interface

d. SDU throughput

RLC/RRC Interface or RLC/PDCP Interface

L1 Throughput > PDU Throughput > SDU Throughput28. Signal Flow (R99 MO)

a. RRC Connection Request (UL-CCH)

i. TMSI and LAI info

ii. LAC

iii. PSC info including Ec/Io and RSCP level

iv. Establishment cause (CS, PS, VP)

b. RRC Connection Setup (DL-CCH)i. S-RNTI

ii. RLC Mode (AM, UM, TM)

iii. Transport Channel Type

iv. Timers and Parameters

c. RRC Connection Setup Complete (UL-DCCH)

i. Domain Identity (CS or PS)

ii. Security Parameter supported

d. Initial Direct Transfer (UL-DCCH)

i. Notification and Capabilities of UE

ii. Mobile TMSI

e. Downlink Direct Transfer (DL-DCCH)

i. RAND Value, Authentication

f. Uplink Direct Transfer (UL-DCCH)

i. Authentication Response

g. Security Mode Command (DL-DCCH)

i. Ciphering and Integrity

h. Security Mode Complete (UL-DCCH)

i. Response from UE

i. Uplink Direct Transfer (UL-DCCH)i. Authentication Code

j. Downlink Direct Transfer (DL-DCCH)

i. CC Call Proceeding

k. Radio Bearer Setup (DL-DCCH)

i. Transport Channel Info

l. Radio Bearer Setup Complete (UL-DCCH)

i. Response from UE

m. Downlink Direct Transfer (DL-DCCH)

i. Alerting

n. Downlink Direct Transfer (DL-DCCH)

i. CC Connect

o. Uplink Direct Transfer (UL-DCCH)

i. Connect Acknowledgement

29. Load Controla. Load Monitoring (LDM)

b. Load Reshuffling (LDR)

c. Overload Congestion Control (OCL)

30. Load Reshuffling Actions:

a. First Action Code Tree Reshuffling

b. Second Action Inter Frequency HO

c. Third Action BE Service Rate reduction

d. Fourth Action Renegotiation of QoS real time services

31. Scanner vs UE Data

Scanner is used to scan all carriers and DL Scrambling codes, while UE measures only codes of informed cells (through BCH and measurement control Neighbor List)

32. INTER RAT Types:

a. IRAT Handover (CS)

b. IRAT Cell Change Order (PS)

33. Call Flow for IRAT Handover:

a. RRC Measurement Report

UL

b. Physical Channel Reconfiguration

DL

c. Physical Channel Reconfiguration CompleteUL

d. Handover from UTRAN Command GSM

DL

e. Handover Complete

34. Call Flow IRAT Cell Change Order

a. RRC Measurement Report

UL

b. Physical Channel Reconfiguration

DL

c. Physical Channel Reconfiguration CompleteUL

d. Cell Change Order from UTRAN

DL

e. Immediate Assignment

DL

f. Authentication Response

UL

g. TMSI Relocation Complete

UL35. Compressed Mode Methods

a. SF/2(CS, PS)

Code Compression

b. HLS(PS only)

Higher Layer Scheduling

36. IRAT HO due to Overload event 3A

37. Physical Channel Reconfiguration Message details

a. gsm-Carrier RSSI Measurement

b. gsm-Initial BSIC Identification

c. gsm-BSIC Reconfirmation38. Huawei Tools :

a. Genex U-Net

(Planning and Simulation)

b. Genex WCDMA Probe

(Drive Testing and Logging)

c. Genex Assistant

(Post Processing)

39. Huawei NodeB Type

a. BTS3812

(GSM BTS upgradable to WCDMA)

b. BTS3900 A

(Macro Indoor)

c. BTS3900 E

(Macro Outdoor)

d. BTS3900 C

(Indoor Compact Micro)

e. DBS3900

(Distributed NodeB with BBU and RRU)1. The output of coverage planning is needed for which one of the following processes?

A. Code planning.

B. Transmission planning.

C. Propagation model tuning.

D. Loading field measurements.

Answer: A

2. If the cell range of 12.2 kbps voice service with 141.9 dB path loss is 2.3 km, what is the size of the cell area with omni-directional site (k factor for site area is 2.6)?

A. 12.2 km?

B. 13.8 km?

C. 15.9 km?

D. 16.6 km?NP

Answer: B

3. Which one of the following services has the HIGHEST processing gain?

A. 12.2 kbps AMR voice.

B. 64 kbps RT data.

C. 64 kbps NRT data.

D. 384 kbps NRT data.

Answer: A

4. Which one of the following parameters can be measured with a UE connected measurement system but NOT with a scanner measurement system?

A. P-CPICH Ec/No.

B. BLER.

C. SIR.

D. Scrambling code.

Answer: B

5. The possible pilot pollution area can be detected from which one of the following?

A. Ec/No lower than target and low number of scrambling codes seen.

B. Ec/No lower than target and high number of scrambling codes seen.

C. Ec/No higher than target and low number of scrambling codes seen.

D. Ec/No higher than target and high number of scrambling codes seen.

Answer: B

6. How can capacity (interference) be improved?

A. Usage of transmission diversity.

B. Increasing transmission power of UEs.

C. Decreasing speed of UEs.

D. Increasing SHO.

Answer: A

7. For the use of a shared antenna line between GSM and WCDMA, what is needed?

A. Coupler or splitter.

B. One shared BTS for GSM and WCDMA.

C. Same output power both GSM and WCDMA.

D. Diplexer or triplexer.

Answer: D

8. Which one of the following is NOT a method to decrease inter-system interference?

A. Tighter filtering for the Tx signal of GSM BTS.

B. Proper frequency planning in GSM.

C. Usage of shared antenna line.

D. Careful antenna selection and placing.

Answer: C

9. The most appropriate reason for Power control headroom is to:

A. improve the downlink reception.

B. maintain the fast power control at the cell edge.

C. compensate slow fading.

D. increase the transmitting power of user equipment (Ue).

Answer: B

10. What is the MAXIMUM number of P-CPICH signals, of similar strength, that the UE should measure?

A. 1 WBTS cell.

B. 2 WBTS cells.

C. 3 WBTS cells.

D. 4 WBTS cells.

Answer: C

11. Considering 1 site (3 cells) with 1 only one carrier per cell, how many traffic hardware channels are needed if in the site the active users are: 1.8 voice, 0.7 CS64, 0.7 PS64 and 1 PS384 and knowing that for each connection the following hardware channels apply: 1 for voice, 4 for CS64, 4 for PS64 and 16 for PS384 are needed?

A. 4

B. 13

C. 24

D. 37

Answer: C

12. Considering 1 site (3 cells) with 1 only one carrier per cell, what is the downlink throughput (in Kb/s) PER CELL if in the site the active users are: 1.8 voice, 0.7 CS64, 0.7 PS64 and 1 PS384?

A. 64.94.

B. 165.19.

C. 194.82.

D. 514.76.

Answer: B

13. For what reason should the power control strategy be changed?

A. UE location.

B. UE type.

C. UE service.

D. UE speed.

Answer: D

14. Which one of the following network planning tasks is NOT normally performed with a radio network planning tool?

A. Coverage planning.

B. Traffic calculation.

C. Hardware channel calculation.

D. Monte Carlo Simulation.

Answer: C

15. The Node B antenna gain is 17 dB and receiver sensitivity 112 dBm, radiated power (EIRP) of user equipment (Ue) is 18 dBm and feeder cable loss is 3 dB. What is the MAXIMUM path loss?

A. 114 dB

B. 116 dB

C. 144 dB

D. 147 dB

Answer: C

16. If the cell radius is 2 km and the required service area is 100 km2,how many 3-sector sites (in coverage-limited case) are needed to provide the service for the area (k factor for site area is 1.95)?

A. 5

B. 8

C. 13

D. 19

Answer: C

17. What is the interference margin for 50% and 90% network loads?

A. 3.0 dB and 10.0 dB.

B. 5.0 dB and 1.5 dB.

C. 3.0 dB and 7.0 dB.

D. 4.0 dB and 10.0 dB.

Answer: A

18. When applying the free space propagation loss formula both for GSM 1800 and WCDMA, what APPROXIMATELY is the propagation loss difference between the systems, if the distance from the BTS is 1500 meters? (Use frequency

2100 MHz for WCDMA.)

A. 5.5 dB.

B. 1.3 dB.

C. 7.4 dB.

D. 13.4 dB.

Answer: B

19. Which one of the following does NOT make the UL adjacent channel interference worse?

A. UE transmitting with maximum power.

B. UE uses hard handover.

C. Other operator BTS in a bad location.

D. Own BTS transmitting with high power.

Answer: D

20. The required Eb/No value is dependent on which one of the following factors?

A. Base station antenna gain.

B. Speed of the user equipment (Ue).

C. Fast fading margin.

D. Body loss.

Answer: B1- What are the main KPI to measure the performance of 3G cell

- Accessibility ( RRC , RAB , CSSR)

- Retainability (speech , Video , PS DCR)

- Mobility (SHO , IRAT HO success rate)

2- What resources affect HSDPA throughput in 3G system

- (DL power, DL code and transport capacity)

3- What parameter tuning can be done to improve HSDPA throughput in any 3G cell

- increase the DL channelization codes for HSDPA

- changing the scheduling algorisms

4- How can we reach 21 Mbps in P7

- 15 codes in DL and 64 QAM

5- what is the usage of the following signaling messages in RRC protocol

- Actives setup updates (ADD/Remove/Replace RL in SHO)

- RB reconfiguration (channel switching between Cell_DCH and Cell_FACH RRC stats)

- Physical channel reconfiguration (IF HO)

6- what is the use of GPEH tool in Ericsson system

- tool used to record RAN and internal events in Ericsson system and the tracing files can be analyzed by TEMS visualization

7- what types of congestion can affect the services accessibility in any 3G cell

- DL power ( AMR - Directed retry - reducing High R.99 RAB users SFxx parameters)

- UL/DL CE ( reducing High R.99 RAB users SFxx parameters)

- DL code (reducing static codes for HSDPA AMR-Directed retry)

- Transport capacity

8- what is the difference between RSCP and EC/No measures for pilot channel

- RSCP is received signal code power for CPICH channel

- Ec/No is The received energy per chip divided by the power density in the band . it reflects the quality of CPICH channel

9- what is the difference of using 2nd carrier and high power amplifier in expanding the capacity for any 3G cell

- 2nd carrier gives capacity in DL power and DL codes

- High power Amplifier gives capacity in DL power only

10- what is the max bit rate that can be achieved in UL when using 10ms EUL and 2 ms EUL

- 1.5 Mbps for 10 ms EUL

- 5.76 for 2 ms EUL

11- how many HSSCCH channel can be configured in HSDPA cell (

- Four that allows four users per TTI