Handover Types

• Intracell same cell, other carrier or timeslot

• Intercell between cells (normal case)

• Inter-BSC between BSC areas

• Inter-MSC between MSC areas

• Inter- PLMN e.g. between AMPS and GSM systems

intracell

intercell

inter-BSC

Handover Criteria

1. Interference, UL and DL

2. Bad C/I ratio

3. Uplink Quality

4. Downlink Quality

5. Uplink Level

6. Downlink Level

7. Distance

8. Rapid Field Drop

9. MS Speed

10. Better Cell, i.e. periodic check (Power Budget, Umbrella Handovers)

11. Good C/I ratio

12. PC: Lower quality/level thresholds (DL/UL)

13. PC; Upper quality/level thresholds (DL/UL)

Location Area Design 1/2

• Location updating affects all mobiles in network

• LocUp in idle mode

• LocUp after call completion

• Location updating causes signalling and processing load within the network (international LocUpdate !)

• Avoid oscillating LocUpdate

• Trade-off between Paging load and Location Update signalling Location area 1

Location area 2

major road

Location Area Design 2/2

• Different MSC can not use the same LAC.

• Location areas are important input for transmission planners • should be planned as early as possible.

• Never define location area borders along major roads!

• Dual band or microcellular networks require more attention on LAC planning

• co-located DCS and GSM cells are defined to the same LAC • same MSC to avoid too much location updates which would cause

very high SDCCH blockings

Network Optimisation

• Improving network quality from a subscribers point of view.

• Improving network quality from an operators point of view.

Network Optimisation is:

What is network quality?

O

P

E

R

A

T

O

R

C

U

S

T

O

M

E

R

NETWORK

SERVICES

MOBILE

COST

• Mail Box, Data, Fax, etc.

• Customer Care

• Faulty H/W or S/W • Mobile Quality • Misuse of Equipment

• H/W Failure • Network Configuration • Network Traffic • Spectrum Efficiency

• Coverage yes/no • Service Probability • Quality • Call Set Up Time • Call Success Rate • Call Completion Rate

H/W Costs Subscription/Airtime costs Additional Services Costs

Network Equipment Costs Maintenance Costs Site Leasing Costs Transmission Link Costs

Overall Network Quality

Cell Planning Tools

• Prediction

• Simulation

Network Measurement Tools

• Propagation

• Drive test

Network Management System

• Network configuration

• BSS parameter data

• Network performance

Tools for Optimisation

Performance Feedback

• Network is under permanent change

• ==> detect problems and symptoms early!

OMC

field tests

customer complaints

It´s far too late when customers

complain!

Optimize compared to what?

Key Performance Indicators, KPI

• KPIs are figures used to evaluate Network performance. • post processing of NMS data or • drive test measurements data

• Usually one short term target and one long term target. • check the network evolution and which targets are

achieved

• KPIs calculated with NMS data • network performance on the operator side.

• KPIs from drive test • performance on the subscribers side

• Usually turn key projects are evaluated according to some predefined KPIs figures like drop call rate

Network Performance Evaluation with NMS

• The most reliable KPIs to evaluate the network performance with NMS are:

• SDCCH and TCH congestion • Blocking percentage [%] • Drop call rate [%] • Handover failure and/or success rate • Call setup success rate • Average quality DL and UL

• The targets are always defined by the customer but the following figures can be considered as satisfactory results:

• Item limit Target • Dropped calls: <3% (at Network Level & 5% at cell Level)

• Handover success >90 % • Good Qual samples (0..5) >90 %

Drive Test Measurements

• Evaluate network performance from the subscriber point of view

• KPIs information: • DL quality, call success rate, handover success rate, DL signal level • not statistically as reliable as NMS information

• Added value of drive test measurement : • find out the geographical position of problems like bad DL quality to

look for a possible interference source in the area • compare the performance of different networks • display the signal level on the digital maps to individuate areas with

lack of coverage eventually improve the propagation model • verify the neighbour list parameter plan

Optimisation Process

• There are not strict processes for optimization because the activity is driven by the network evolution.

Optimisation Process: Young Network Case

• In a young network the primary target is normally the coverage.

• In this phase usually there is a massive use of drive test measurement • check the signal and • the performance of the competitors

GPS

NMS X

MMAC

Optimisation Process: Mature Network Case

• In a mature network the primary targets are quality indicators • drop call rate, average quality, handover failures.

• Important use the information from NMS • a general view of the network performance.

• Drive test measurements are still used • but not in a massive way • in areas where new sites are on air • where interference and similar problems are pointed out by NMS data

analysis.

Drop Call Rate (%)

0

0.5

1

1.5

2

2.5

3

3.5

Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed

Call Bids / 10000

Average

Busy Hour

Site Database

• Project team to provide the list of sites to be integrated in the following week.

• For Multi BTS towns sequence of sites also need to be provided.

• RF team to provide the BSS database within the next 2 working days.

• BSS to integrate the database in the OSS & confirm to NWP

Database Verification

• Verification of database dump by RF team using Plan editor or other tools by partners.

• TSC should be same as BCC • RF engineer to be associated with OSS/BSS for dump verification • Any inconsistencies to be escalated to BSS team for rectification.

• Netdoc Reports for Adjacencies. • Adjacencies discrepancies & One way Adjacencies to be cleared. • Adjacencies having same BCCH,BSIC , to be analysed & cleared. • Adjaciencies within same BTS but are not synchronised & adjaciencies which

are not in same BTS but are defined synchronised.

ALL ABOVE REPORTS TO ALL CONCERNED ON WEEKLY BASIS

Drive Testing Process-Prerequisites

• The Circle to be divided into zones , comprising multiple SSA,’s . • Each Drive Test team to be allocated a particular zone. • Multiple DT teams (max3) to be supported by Optimisation engineer.

• Database verification to be completed before DT team reaches site.

• Inputs from Installation / Project Team • VSWR Readings • Power o/p per TRX • BTS synch report.

• Verify that no. of active Alarms at BTS

Drive Testing Process-Prerequisites

• Drive Test Team • Rigger with compass/tilt meter & spanner set • Site data base (Ant Height,tilt , orientation, NR list) • Coverage plot (soft copy)

• Physical Verification of site • Basic antenna height check • Antenna Orientation , any physical blocking • Tilts • Conduct clockwise DT to check for Feeder swaps.

• In case of installation issues (incorrect antenna height etc) or BTS hardware issues , to be escalated to Optimisation engineer .

• Input from DT Analyser regarding any HO,Drop , other issues.

Drive Testing Process

• Drive Test Team(should be accompanied with Riggers) • Rigger with compass/tilt meter & spanner set • Site data base (Ant Height,tilt , orientation, NR list) • Coverage plot (soft copy)

• Physical Verification of site • Basic antenna height check • Antenna Orientation , any physical blocking • Tilts • Conduct clockwise DT to check for Feeder swaps.

• Input from Optimisation engg regarding any HO,Drop , other issues.

• Conduct Drive Test • 1-2 site town , disable pwr control from OSS • Multiple city town , conduct Idle mode & dedicated mode DT using 2 handsets.

• Apart from these drive test, it is also important to map the customer complaint database to the performance reports . This helps the optimization engineers in knowing the real end user experience of the network.

Drive Testing Process

• Drive test data to be sent to the optimisation engineer on a daily basis.

• DT Data to be analysed by the DT Analyser by replaying the drive files using TEMS/Neptune.

• DT Data & the daily statistics to be analysed by DT Analyser.

• All physical changes (tilt,orientation ) to be communicated to the DT engineer & also modified in the master database.

• All parameter changes to be communicated to BSS/OSS engineer by a change request form. Urgent changes to be communicated to OSS engg over phone & Change Request form can be sent over mail.

• Completion of Optimisation of city. • OSS statistics as per benchmarks • Rx Level Plot as per coverage plot • Rx Quality, as per A/T benchmark • CSSR,HO success rate,drop as per A/T benchmark • The above report to be submitted to the Nokia circle lead

Optimization team structure

Circle Team leader

Analyze Daily Rf reports, Suggest Optimization tactics,

Consolidate Optimization status, Verify Change requests

and resource management

Optimisation Engineers

Analyze Drive test log files, customer complaints and

Physical parameter settings

Core Opti. Engineers

Analyze Daily KPI, Alarm logs, Parameter audit, Soft Parameter

recommendation

Drive tester

Conduct drive test after and before optimization, collect field

data, co-ordinate with Rigger

Rigger

Change Physical Parameters like Antenna Direction & Tilt

Cross Functional Tasks and Responsibilities

Tasks:

• Site radiation plan

• VSWR,TRX power data

• Troubleshooting Hardware related problems at site

• Soft changes for optimization

• Overall City Optimisation

Responsibility:

• Project Coordinator

• Project Coordinator

• BSS

• BSS/OSS

• NWP

•The time frame for implementation of the hardware issues is 24 hours from the time the change request is raised. •The time frame for implementation of the soft changes is the same night the change request is raised. For changes that can be done online, the time frame in 2-4 hours from the time the change request is issued

•After the change has been carried out the implementation teams and the OSS teams should inform the optimization team leader for the respective zone and Update the change request tracker. •The optimization teams will then do a verification drive or statistics monitoring To verify the results.