What are Events that can trigger the HSDPA Cell Change?

Event 1d HS – Change of Best Cell in the Active Set
Event 1b or Event 1c – Removal of the Best Cell from the Active Set

HSDPA Optimization

HSDPA Planning

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 are the possible causes for an Access Failure in UMTS?

• Missing Neighbors
• Poor Coverage
• Pilot Pollution / Spillover
• Poor Cell Reselection
• Core Network Issues
• Non – availability of resources. Admission Control denies
• Hardware Issues
• Improper RACH Parameters
• External Interference

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Ericsson Parameters to make Handover Easier

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 can we try to improve when access failure is high?

When access failure is high we can try the following to improve RACH performance:

• Increase maximum UE transmit power allowed: Max_allowed_UL_TX_Power.
• Increase power quickly: power_Offset_P0.
• Increase number of preambles sent in a given preamble cycle: preamble_Retrans_Max.
• Increase the number of preamble cycles: max_Preamble_Cycle.
• Increase number of RRC Connection Request retries: N300.

Know What are the Possible Reasons for Access Failure in UMTS?

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.

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