RRC Establishment Causes

RRC Establishment Cause Description
Cause 0 Originating Conversational Call
Cause 1 Originating Streaming Call
Cause 2 Originating Interactive Call
Cause 3 Originating Background Call
Cause 4 Originating Subscribed traffic Call
Cause 5 Terminating Conversational Call
Cause 6 Terminating Streaming Call
Cause 7 Terminating Interactive Call
Cause 8 Terminating Background Call
Cause 9 Emergency Call
Cause 10 Inter-RAT Cell re-selection
Cause 11 Inter-RAT Cell change order
Cause 12 Registration
Cause 13 Detach
Cause 14 Originating High Priority Signaling
Cause 15 Originating Low Priority Signaling
Cause 16 Call re-establishment
Cause 17 Terminating High Priority Signaling
Cause 18 Terminating Low Priority Signaling
Cause 19 Terminating – cause unknown


 

What will be the impact when you change ‘reportingrange1a’ from 3 to 4 dB and ‘timetotrigger1a’ 100 to 320 ms, without changing any other parameters?

• Reduction in number of Event1a
• Delayed Event1a trigger
• Reduction in Average Active Set Size
• 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)

What is Soft Handover Overhead? What is the typical value in UMTS network?

• Soft Handover Overhead is calculated in two ways. 1) Average Active Set Size – Total Traffic / Primary Traffic. 2) Secondary / Total Traffic
• Typical Values are like 1.7 (Avg Active Set Size) or 35% (Secondary / Total )

How to improve Soft Handover in UMTS Network?
How can we avoide to many Soft Handover attempts?

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?

• 6 to 9 seconds
• Multiple RRC Attempts (UE is on poor coverage – need more than Access Attempt)
• Delayed Page Responses
• High Load on Paging and/or Access Channel
• Paging / Access Parameters

Download UMTS Radio System Planning and Optimization Guide

What is Hard Handover in UMTS? When will it happen?

· Hard Handover in UMTS is a break before make type Handover
· It can happen in the inter RNC boundaries where there is no Iur link.

This may Helpful to You

IRAT Handover Guide
Inter System Cell Reselection Optimization Guide
TEMS UMTS Dropped and Block Call Specification 

What are the possible causes for a lower PSR?

There are several different reason for low Paging Success Ratio

- Non-continuous RF Coverage – UE going in and out of coverage area frequently
- Very High ‘Periodic Location Update Timer’ – Keeping UEs in VLR long time after it moved out of coverage
- Lower Paging Channel Power
- Access Channel Parameter Issues
- Delayed Location Update when crossing the LA / CN Boundaries

Also Check

E Book on GPRS and EDGE Performance

What is G-RAKE Receiver?

What is Paging Success Ratio? What is the typical PSR that you have seen in a WCDMA UMTS network?

Paging Success Ratio:

Its Paging Responces to the Paging Attempts in WCDMA UMTS network.

Typical Value for Good WCDMA Cellular Network is greater than 90%. 

What is the typical event sequence of IRAT Handover from 3G to 2G

Simple IRAT Handover Flow

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

Download Complete UMTS CS Call Flow

What are the typical KPIs you use to measure a network and what criteria?

• Access failure rate (≤ 2%).
• 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).
• Dropped call rate (≤ 2%).
• BLER: over 95% of the blocks ≤ 2%.
• Average DL/UL throughput for PSD: 210kbps for loaded, 240kbps for unloaded.

Find the complete UMTS KPI from Here

Information on UMTS KPI BenchMark

CPICH Optimization

Good Document on CPICH Optimization from Maxis

CPICH Optimization

You can view Document Here

Content

• Objective
• Technical Background
• Deployment Area
• Performance Results
• Traffic Results
• Capacity Results
• Summary

Download Full Document in PDF from Here

Deployment of CPICH optimization is driven by:
–Improving current 3G coverage and increase 3G traffic
–Improve in-building penetration for 3G
–Reduce IRAT HO to 2G
–Offload traffic from 2G layer

How Can We Avoide IRAT Handover?
Traffic Shift Strategy for 3G to 2G

What are the conditions you typically set to trigger IRAT handover?

RSCP and Ec/Io are used to trigger IRAT handover:

1.       RSCP ≤ -100dBm.

2.       Ec/Io ≤ -16dBm.

Find more document on IRAT
WCDMA IRAT Handover
Details on IRAT Parameter Optimization Document

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.

Know more about Scrambling Code

UMTS Scrambling Code Planning Guide

Consider downlink only, what are the major components in calculating maximum path loss, starting from NodeB?

·         NodeB CPICH transmit power.

·         Jumper and feeder connector loss.

·         Antenna gain.

·         Over-the-air loss.

·         Building / vehicle penetration loss.

·         Body loss.

Parameter Dictionary from well known Vendor
Google Mapinfo Tool

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.

HSDPA Network Planning Guide

What is Difference between ARQ and HARQ?

HSDPA Measurement Events

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:

• The coverage area is small since users are close to the site, and
• More power can be allocated to traffic channels.

Find UMTS Questions and Answers

Nemo Outdoor and Analyzer Training Slides

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.

What is Power Congestion in UMTS?

How We can tune 3G Network?

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.

Download Excel sheet of UMTS Link Budget

What is a typical soft handover gain in your link budget?

•          CS-12.2k:      3dB (UL), 2dB (DL)
•          PS-64k:         1dB (UL), 0dB (DL)
•          PS-128k:       1dB (UL), 0dB (DL)
•          PS-384k:       1dB (UL), 0dB (DL)

Know more about 

How does Soft Handover Work?

WCDMA Soft Handover Procedure

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.

Download More

Detail Doc on Layer 3 Messages

Call Flow with Layer 3 Messages on Ericsson System

Brief describe the advantages and disadvantages of soft handover?

Advantages:

·         Overcome fading through macro diversity.

·         Reduced Node B power which in turn decreases interference and increases capacity.

·         Reduced UE power (up 4dB), decreasing interference and increasing battery life.

Disadvantages:

·         UE using several radio links requires more channelization codes, and more resources on the Iub and Iur interfaces.

More Dowload For You:

Actix Tutorial