Optus Indoor Solution

RAS/SD/SP Optus Indoor Solution Development Project

OPTUS INDOOR SOLUTION

DEVELOPMENT PROJECT

(NOKIA – OPTUS CONFIDENTIAL)

B6Y 059027AE

R, 03/01/-1,

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ã COPYRIGHT Nokia Telecommunications 1997

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INTERNAL HISTORY PAGE

Archive

Location: \\essrv01nok\nhras\sd\rntools\pctrials\nokiapcs\trial\Optus\

Filename: Nokia_Optus.doc

History

Date Version Author Change Note No./Notes

18.08.98 0.0.1 See Chee Yoong First draft

21.09.98 0.0.2 See Chee Yoong Second draft

11.10.98 0.1.0 See Chee Yoong Ready for finalize

22.10.98 0.1.1 See Chee Yoong



APPROVAL PAGE

Written by: See Chee Yoong.............................................. Date: 15.10.98

Checked by:........................................................................ Date:............................

Approved by:....................................................................... Date:............................



CONTENTS

ABBREVIATIONS..............................................................................................7

EXECUTIVE SUMMARY................................................................................8-9

1. Introduction..........................................................................10

1.1 Objectives............................................................................10

1.2. Backgrounds...................................................................11-14

2. Case Study Procedures..................................................15-16

3. Project Tools...................................................................16-17

4. Buildings and Configurations...............................................18

4.1 Test Case Building Description.......................................18-23

4.2 Building Showcases.............................................................24

5. Walking Test Measurements Results.............................18-20

6. Power Reduction Case Study..............................................28

6.1 Results and Findings......................................................28-35

7. Frequency Hopping..............................................................36

7.1 Commands for Implementing the Frequency Hopping........36

7.2 Results and Findings...........................................................37

7.2.1 RF Hopping.....................................................................37-43

7.2.2 BB Hopping.....................................................................44-46

8. Intelligent Underlay Overlay.................................................47

9. Parameter Sensitivity Studies..............................................48

9.1 Maintaining the Indoor Traffics.......................................48-52

9.2 Solving In-Lift Drop Calls Problem..................................53-54

10. Seeder Signal – Coupler Connection and Concept........55-56

11. Frequency Allocation Methods.......................................57-61



12. Traffic Absorption Measurement.....................................62-68

13. Interference Between Adjacent Indoors...............................69

14. Case Studies Evaluation.................................................69-70

15. Conclusion......................................................................71-72

16. References...........................................................................73

APPENDIX A: Actual Parameters Changed in FMT HO Case Study........74-80

APPENDIX B: Sample Power Budget Calculation and Antennae Layout. .81-85



ABBREVIATIONS

BB BasebandBER Bit Error RateBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDCS1800/1900 Digital Cellular System at 1800/1900 MHzDL Down Link (connection from BTS to MS)DTX Discontinuous transmissionEIRP Effective Isotropic Radiated PowerFER Frame Error RateFH (Slow) Frequency HoppingFS Field StrengthGPA General Protocol AnalyserHO HandoverHSN Hopping Sequence NumberIUO Intelligent Underlay OverlayLOS Line Of SightMS Mobile StationMSC Mobile Switching CenterNLOS Not Line Of SightOMC Operation and Maintenance CenterPCN Personal Communication SystemRF Radio FrequencyRX Receiving SW SoftwareTRX TransceiverTS TimeslotTX TransmittingUL Up Link (connection from MS to BTS)



EXECUTIVE SUMMARY

Nokia proposed this In-building Solution Development Project in May 1998 as part of the lead

account initiative. The objective is to achieve a better understanding of indoor network

behaviour in Australian environment, identify limitations and improvement to current solutions

technologies and application of BSS functionality, identify new solution concepts as well as

develop more join R&D work between Optus and Nokia.

Overseen by a steering group with both Optus and Nokia representatives, the Nokia project

team conducted 11 man months of testing to 8 selected in-building systems between June

and September 98. These 8 buildings were selected for their diversity of radio characteristic.

They included both low rise and high rise buildings. Radio signal distribution technologies

used included Fibre Optic Repeater, leaky feeder network and passive Distributed Antenna

System (DAS). These buildings offered the varied environment for multiple radio network

concepts be assessed.

The 7 key concepts being investigated in the project are:

traffic absorption of in-building systems

frequency planning and signal isolation between in-building systems

impact of signal level on the performance of in-building system

The use of Nokia Handover features in indoor environment

The use of Nokia Intelligent Underlay Overlay feature in indoor environment

The use of Frequency Hopping in indoor environment

Solution concepts to solve lift call drop problem

On the traffic absorption issue, the project concluded that the in-building cells stimulate

mobile usage and generates additional traffic to the network area. Up to 10% immediate

increase in network traffic was observed in the cases studied.

On the frequency planning issue, the study examined 2 office tower of 200m apart and

confirmed that radio signal isolation between was good enough for frequency re-use between

them.



It was concluded in the signal level studies that relative signal level combined with the

frequency plan of an in-building cell play a critical role on the system performance. Because

of the tight and mixed frequency re-use strategy, signal level domination is needed to ensure

a good network performance.

The use of multilayer network topology with Fast Moving Mobile Handover in an in-building

cell returned some encouraging result. The handover function retained more traffic inside

the building and avoided typical problems like ping-pong handovers.

Because of the better radio signal isolation in an in-building environment, there was believed

that Nokia Intelligent Underlay Overlay could deliver more spectrum efficiency gain. The

study confirmed that is the case and proved that IUO can be used in high traffic in-building

systems.

On the use of frequency hopping in low-rise building, the study concluded that noticeable

improvement to both quality and received signal strength could be achieved. However,

another case investigated concluded that the law of diminishing of return applies to network

quality, the use of frequency hopping in a reasonably well performing building did not deliver

significant improvement.

It is also observed that top sectors of a multiple sector high rise building were showing a

higher call drop rate. Further investigation is needed to identify improvement to the situation.

On the other hand, in lift call drop problem has been investigated and two solution ideas

were tested. The Seeded Signal concept was found to be promising and further trial is

recommended.

Throughout the project, Optus offered support and expertise input to the steering group.

Nokia would like to thank Optus for this rare opportunity of conducting the investigation in a

live network.



1. INTRODUCTION

1.1 Objectives

This document is aimed to present the findings of Optus Indoor Solution Development

Project conducted in Melbourne and Sydney, Australia during the winter season of 1998.

This development project has provided different indoor test cases, which are conducted in

different indoor cells. The objectives of these test cases include:

Qualifying the performance of existing indoor solutions

Qualifying the performance of indoor cells compared to indoor service provided by

outdoor cells

Qualifying the performance of indoor cells in a multi-layer network (macro-micro-

indoor) and with IUO in macro and in an indoor cell

Sensitivity study of parameters

Power levels and channel allocation in indoor cells

Verification of frequency allocation concepts

Verify the usage of FH and IUO in indoor cells



1.2 Backgrounds

Different Indoor Solution

3. Distributed Antenna System (with Amplification)

2. Radiating CableBTS

4. Optical RF distribution RF o utRF in

O p t Tx

O p t RxRF o ut

RF o ut

RF o ut

5. Integrated Optical RF Distribution

6. Mini BTS Flexitalk and Prime- Site

GSM RF

Optical Sign.

RF o ut . . .

. . .

. . .

Indoor cell1. Single Antenna System

7. RF repeater for Indoors

8. RF Repeater with optical interface

Outdoor cell

BTS

9. Passive Repeater

Optical Sign.Optical Sign.

GSM RF

GSM RF

Indoor cell

An optimal solution can be built to meet the coverage needs for each environment by

combining different signal distribution methods with coaxial, omni or directional antennas.

The figure above gives an overview of the solutions available. In this project, several indoor

solutions have been encountered. These included distributed antenna system (DAS), optical

RF distribution and radiating cable. Please refer to the document “Indoor Planning and

Solution” for more information regarding different indoor solution issues.



Frequency Hopping

FH is an optional feature in GSM. Benefiting from the complex scheme in GSM, which uses

channel coding and interleaving, the gain from FH is two folds:

(I) Frequency diversity -

The negative impact of fading is reduced through frequency selective nature of fading

in urban environments. Frequency diversity allows for reduced fading margins that

are included into link and interference budgets. This allows for more dense frequency

reuse and provides improved coverage (for slow moving mobiles in shadowed areas).

(II) Interference diversity -

The interference is averaged over multiple frequencies. The interference diversity

gain comes from averaging of the interference over multiple frequencies. This

provides a more equal perceived quality for all the mobile connections, and especially

the number of connections with very poor quality is significantly reduced. The

interference diversity gain from FH is most significant in a combination with either RF-

power Control (PC) or Discontinuous Transmission (DTX).

The gain of FH can be used either to improve the quality of the network (the frequency plan

is not changed) or increase the capacity of the network (the frequencies are used more

often). “Frequency Hopping in Nokia BSS” gives a throughout insight on this issue.

Verification of Intelligent Underlay-Overlay Usage for Indoor

IUO has the ability of increasing the capacity of a network. The increased capacity in IUO is

due to the ability to use frequencies more efficiently than in conventional single-layer

networks. The good C/I probability is one of the key factors in the IUO performance and

capacity studies.

In the case of uniform traffic distribution, the probability value equals to the interference free

area of the cell determined by the C/I thresholds. In real life the traffic distribution is rarely

uniform over the cell area and this should be considered in the calculations. The good C/I

probability has been defined as a proportion of the total cell traffic (TCH reservation time)

having C/I ratio above certain threshold. C/I calculation is based on the downlink RX levels

reported by a mobile station. Because the resulted C/I ratio is an estimation which calculated

from the BCCH signal of the neighbours and the serving signal, the same kind of C/I Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (12)


evaluation procedure can be produced without IUO. The mobile measurement reports are

collected and the RX levels are compared using the same methods as BSC uses in IUO. In

the implemented solution, the mobile measurement reports are collected from Abis-interface

with the use of NetHawk GSM Protocol Analyser, which can be connected to any channel

in the connection between BTS and BSC.

Power Reduction

Power reduction is a useful mechanism for reducing the overspill of indoor signal, providing

that it does not affect the performance of the cells. It may also improve the UL quality by

balancing the link budget. If the DL signal is greater than the ‘Rx level access min’

parameter, a call can be made even when the UL signal is weak. Indirectly by reducing the

power, it can ensure calls to be made only if a reasonable UL signal is sustained. Apart from

these, it can isolate the cell from others. As a result, no interference is experienced.

Parameter Sensitivity Studies

Handover Parameters

Four types of handover have been used and analysed, namely power budget HO (PBGT

HO), umbrella HO, radio reason HO (RR HO) and fast moving MS HO (FMT) respectively.

Each of these has their own handover algorithm. Please refer the document “RF Power

Control and Handover Algorithm” for the detail procedures.

Rapid Field Drop

Rapid Field Drop is an optional feature in BSC. The BSC recognises the necessity to make a

handover when the HO threshold comparison indicates that a handover, cause rapid field

drop, might be required from the serving cell to a specified adjacent cell. The situation can

take place when a mobile moves so fast from one micro cell to another that the up link is lost.

When the cause is rapid field drop, only those adjacent cells, which are defined as chained

adjacent cells may be selected as target cells.

Frequency Allocation Concepts

There are many methods that can be used for frequency allocation purpose. The uses of TIM

and TEMS tools are two of the examples. The data collected from both tools can be post-

processed and tabulated into graph format by using simple Excel program. From these Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (13)


graphs, one can select frequencies, which can be considered as clean. The chosen

frequencies can be verified by the use of PlanEdit, in order to determine any close by co-

channel or adjacent channel sites.

Traffic Absorption Measurement Method

An excel program has been developed. It is used for monitoring the traffic profiles for both

macrocells and indoor cells. It is aimed to identify how the traffic profiles for the neighbour

macrocells changing before and after the indoor cell has been implemented.

Interference Between Indoor Sites

The target is to evaluate the minimum frequency reuse distance between two indoor sites.

This can be done by monitoring the UL interference of the idle TSL's together with DL test

survey measurements.



2. Case Study Procedures

The following flowchart describes the procedures of each case study:

The initial benchmarking process using both NMS2000 statistic and TEMS are essential in

determining how the existing indoor cells perform and what to be done in order to improve

the cell performance. TEMS is used to measure the existing indoor coverage as well as its

quality, with both active and idle mode measurements. It also can be used to scan the Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (15)

Yes

En

d

Conducting parameter

change

Building Benchmarking with

NMS2000 Statistic and

Walking Test Measurement

Cell

Performan

ce

Case Study Begin

Initial Building Benchmarking

with NMS2000 Statistic and

Walking Test Measurement

Parameter Changing

Proposal

Acceptabl

e ?

No

Good

Not

Good


frequency band in order to select suitable frequencies for the new indoor site. During the

measurement, it is essential to walk slow and walk close to the edge of the buildings. The

reasons are, (I) to collect enough samples at each location and (II) by walking close to the

edge of the building like near the windows, it enables us to observe the worst case situation

i.e. in these areas the interference will be higher than other location. Since TEMS only

depending on 1 single mobile with a particular route, NMS2000 is employed to verify the

overall performance.

Once the initial benchmarking has been conducted, a proposal on what should do is

presented for approval. The changes will proceed once the proposal is considered

reasonable and safe.

Another round of benchmarking will be conducted to verify the performance of the cells after

the changes. At least one to two days is required in determining the performance of a cell. If

time permits, another proposal is presented and the whole process is repeated again.

3. Project Tools

The following are the tools that have been used throughout the project. They are:

TEMS and FICS

CellDoctor

PlanEdit

TEMS is a Test Mobile System. This tool resembles to NMS/X in which it equips with a

mobile phone and a notebook. The differences between TEMS and NMS/X are:

1. TEMS has addition information like Frame Error Rate (FER) and Speech Quality Index

(SQI).

2. TEMS does not contain the map information.

3. The output data of TEMS is not in text format but in ASCII. As a result, it is not possible to

analyse the data manually.

FICS is the analyse software for TEMS data files. FICS uses the input data files to generate

a statistical result.

The Nokia CellDoctor is used for post-processing the PM (Performance Management)

results. It is useful in determining the performance of the indoor cells in each case study. The



scripts can be run either manually or automatically, and the results are collected daily. The

following are the scripts number that have been used in the project:

Script Measurement Level

181 Daily TCH Traffic Profile BTS

190 UL Interference BTS

204 KPI Area

402 IUO, Busy Hour Absorption and Traffic BTS

The script 204 has played an important role in this project. It provides most of the main

statistic results like TCH drop ratio, UL/DL quality, SDCCH success ratio and HO failure ratio.

Another vital tool for this project is PlanEdit. It is intended for off-line data manipulation on the

user interface, not directly for implementation to the network. It requires an ASCII export file

of the parameter data from the NMS/2000 database and then import into the PlanEdit. It can

be used to serve many purposes. In this project, it mainly used for

Verifying the parameters setting

Checking the frequency plan of a BSC

Viewing the parameter tables

Searching for a particular objects through simple query



4. BUILDINGS AND CONFIGURATIONS

4.1 Test Case Building Description

In this section, the building description and layout are presented. Moreover, the indoor

design and configuration are included as well. There are 8 test case buildings involved in the

project.

Melbourne International Airport


This building is made up of 4 levels:

ground floor, first floor, mezzanine

floor and second floor. The building

can be split into three areas, (I)

Ansett Domestic area (II) Qantas

Domestic Area and (III) International

Terminal Area, FAC. The indoor site

is made up of 3 sectors with 2+2+2

configuration. The design uses

optical distributed system with

mostly diamond omni antennas. This

indoor design is aimed to provide

coverage for only hot spot areas like

lobby and check in counters.

Legends:

Omni antennae located in the first floor of International departure area

Panel antennae located in the international departure gates area

Omni antennae located in the ground floor and mezzanine floor of the

Qantas domestic

Omni antennae located in the mezzanine floor of the Ansett domestic

Scale:

200m


Westfield Paramatta

This shopping mall consists of 5 levels. The design uses DAS with the aims of providing both

coverage and capacity.

A

B

C


The diagram on the left is a typical floor

layout on level 3. Each of these color

borders has the following description.

Block A

The sector-1 serving this area.

One panel antenna located in

the main walkway and an Omni

in David Jones on level 4.

Block B

The sector-2 serving the area

with one panel antenna located

in the main walkway and an

Omni in Grace Bros on level 3.

Block C

The sector-3 serves this area.

One panel antenna located in

the main walkway on level 2.Scale: 180m


OCS building

OCS building has 34 levels which include 6 basement car parks. Leaky cables have been

used for this design. In general, they are installed in every thrid floor of the building. The

design is made up of three sectors. OCS-1 and OCS-2 contain 3 TRXs i.e. 2 regular plus 1

super-reuse TRX. OCS-3 has 2 regular TRX in its configuration. The sector-3 is serving the

basement areas and upto level 12. Whereas for sectors 1 and 2, both serve the middle and

high rise levels with a interleaving structure design.


Leaky cable run

Riser

Scale: 17m


Australia Square

This building consists of 48 levels. It makes up of 3 sectors (1+1+1) with the use of DAS.

Each floor contains 2 panel antennas located at the corner across the floor and near to the

core of the building. Sector-1 is aimed to serve the floors from levels 1 to 18 excluding 4 and

5. Sector 2 serving the levels 20 to 34 and sector-3 for levels 36 to 48. No antenna is

installed in levels 4 and 5 to avoid the overspill of indoor signal because the floor is

surrounded by big glass wall. The sector 1 is gateway cell, and the other two cells have only

outgoing adjacency for indoor cells.


Legends:

Directional antennae on level 6 to 1

Directional antennae on level 20 to 50

Communication riser

45m


1’Oconnell


This is a 35 storeys high

building, with sector-1

covers level 1 to 16 and

sector-2 for levels 19 to

35. The design of this

building is very similar to

Australia Square except it

only consist of 2 sectors

with 1+1 configuration.

Legends:

Directional antennae on even tenant floors

Directional antennae on odd tenant floors

Communication riser

40m

40m


Chifley Tower (Telstra Design)


Chifley Tower is a 42 storeys high

buildings. The design is a little bit

different from the other buildings.

The indoor coverage is limited to

certain floors. Instead of having

panel antennas locate at the corner

of each floor, omni antennas are

used (2-4 per floor). These

antennas locate close to the center

of the floor. The design only

contain only one sector with 2

TRXs configuration.

40m

36m


Westside Tower


A 33 floors building. Two sectors is

used to provide the indoor coverage

with 1+1 configuration. The indoor

directional antennae were mounted

at two diagonals of each floor. The

use of DAS design ensures the

coverage from levels 1 to 16 is

provided by sector-1 and levels 17

to 32 by sector-1.

Legends:

Directional antennae on even tenant floors

Directional antennae on odd tenant floors

Communication riser

36m

36m


NRMA building


It is a 28 floors building. The

indoor design is made up of

2 sectors with 1+1

configuration. In this building,

a 3rd antenna pointing

downwards is specifically

located near to the lift

corridor in order to improve

the lift coverage.

Legend:

Directional antennae

Omni antenna

Comm. Riser

37m

27m


4.2 Building Showcases

Test Case

Me

lbo

urn

e

Air

po

rt

Wes

tfie

ld

Par

amat

ta

OC

S

Au

stra

lia

Sq

ua

re

1 O

’co

nn

ell

Ch

ifle

y

To

wer

Wes

tsid

e

To

wer

NR

MA

Power

ReductionY Y Y

RF Hopping

(1 MA list – 8

frequencies)

Y Y

BB HoppingY

Parameters

StudyY Y Y Y Y

IUOY

Traffic

Absorption

Measurement

Y Y Y

Frequency

Allocation

Method

Y Y Y

Seeding

Signal StudyY

Interference

Between Two

Indoor Sites

Y Y

Table 1: Building Showcases



5. WALKING TEST MEASUREMENT RESULTS

In the following section, one can obtain the results of the walking test measurement for all the

test case buildings.

Melbourne International Airport

Ansett Domestic Area

During the measurement, no drop call has occurred. The overall quality in this area is good

and the field strength is strong (>-85dBm). The indoor cell, Airport Term-3, covers most of

the area. Ping-Pong HO effect has been observed when walks in/out of the building on the

first floor. These HO are between the indoor cell and a macro cell.

Qantas Domestic Area

In this area, the indoor cell, Airport Term-1, mostly serves the MS. The field strength for most

of the indoor cell is good (>-80dBm) with a quality class 0. But there is a portion of the area,

the macro cell from Melbourne Airport-1 becomes the dominant.

International Terminal Area (FAC)

From the result, it shown that the macro cells have stronger field strength as compared to the

indoor cell especially in the ground floor (with no antenna). But on the first and second floors,

the indoor cell, Airport Term-2, mainly serves the MS.

In the ground floor of the International Arrival Hall area, it is noticed that the area is more

likely to be served by the macro cells. Most of the signals have weak field strength of -90dBm

or below with quality class 4-5. From the measurement, it also shown that the area near the

duty free shop has weak field strength (<-90dBm) and a quality class of 4-6 with bad FER

value (the range is between 8% to 50%).

Westfield Paramatta

The Westfield, in general, has good indoor field strength (>-80dBm) and quality with small

drop call rate(2%). There is no overspill of indoor signal outside the building. The three

indoor cells have very well defined serving areas as shown in the diagram above. However,

macro cells have served some areas in Block C. These areas included part of level 1 and

area near the entrance to the mall.



From the measurement, it also illustrated that some shops in Block A like Target, K-Mart

have bad indoor field strength (<-90dBm) with quality class 4-5 and the macro cells are

weak. As a result, it is expected the DCR (drop call rate) in this area is high. Apart from this,

there is no indoor coverage in the Aird Street car parks. Inside the lift near to the Church

Street entry, there is no coverage. Another problematic areas are the Campbell Street car

parks on level 2, 3 and 4. The indoor cells mostly serve these levels. But the indoor field

strength in these parking floors is weak (as whole) especially on level 2.

OCS Building

The walking test results illustrated that the OCS has good indoor field strength and quality.

The use of IUO in OCS-1 and OCS-2 has proven to be very effective. From the walking test,

it has shown that the MS will handover onto the super layer after a short while. In a sense,

the absorption rate is expected to be high. Another positive outcome of the OCS’s design is it

has a well-defined HO border with no over spill indoor signals. Within the building, the indoor

cells serve the MS and outside the building, it is served by macro cells.

However, some problems have been observed when calls are made or maintained inside the

lifts (especially the lifts to level 34th). There are cases where the calls are dropped because

of low field strength. Another possible reason that constitutes the drop calls is the bad

downlink quality, which can be seen from the TEMS traces.

Australia Square

From benchmarking, the walking test results shown that the Australia Square has very good

indoor field strength and quality for both sector 2 and 3. From the cumulative RX Level

graph, it show that for more than 90% of the walking test route was better than –70 dBm.

Whereas, the RX Quality also show that more than 90% of the walking test route was at

Quality Level 0 and less than 0.5% for the Quality Level 5, 6 and 7. From the NMS 2000, the

statistical results shown the SDCCH Drop Ratio was at 6% and the TCH Drop Call Rate was

4%. The reason for higher Drop Call Ratio is mostly due to HO drops in the lift,

TCH_RF_OLD_HO, counter c1014. Sector 1 signal strength was lower than other sector to

ensure that there will be no signal spillage to the street level.



1’Oconnell

In general, the indoor signal strength is good with value better than –60dBm. The overall

quality is good but there were suddenly dropped calls. An over spill of indoor signal onto the

street level is quite noticeable. It was found to cause by an installation problem, in which the

power for sector-1 and sector-2 has been accidentally swap over.

Chifley Tower

No walking-test measurement has been conducted in the building. Only scanning

measurement was performed to determine the hopping frequencies.

Westside Tower

From the test results, it showed that the Macro site, which located next to the building, have

a very high level of field strength coverage for the ground level than the Westside Tower

sector 1. Signal strength for Sector 2 for high rise section were significantly stronger than the

outdoor server was, but there were some problem with the quality.

NRMA Building

Only the in lift measurement was carried out. No drop calls have occurred in the lift. It is

noticed that when the in-building signal is weak, the call was HO to the macrocell and later

back to the indoor cells.



6. POWER REDUCTION CASE STUDY

In order to reduce the transmitting power, one is required to adjust the parameter, Pmax, as

shown in Table 2.

ParameterCurrent

ValueNew Value Comments

BTS Max. Transmit

Power (PMAX)

max-‘X’ max-‘(X+Y)’ X is the attenuation from the peak

power of the BTS. Its range is from

0 to 30dBm. Y is the proposed

power reduction value

Table 2: Power Reduction Parameter

6.1 Results and Findings

The power reduced in each test case is listed as below:

Building Test 1 Test 2

Melbourne Airport

(Qantas Domestic Area)

4 -

Westfield Paramatta 4 6

(Sector 1)

Australia Square

(Sectors 2 and 3)

10 6

Table 3: Power Reduction Value (dB) in Each Building

There are mix results for this case study. Some buildings allow reduction starting from the

range of 4dB up to 6dBm, but some cannot cope with it. Graph 1 below is the result from all

of the tested building showing the relative changes as comparing to the initial benchmarking

results on the Drop Ratios. The relative changes in DL quality and FER for the walking test

results are shown in Graph 2 and 3.





In most cases, power reduction has improved the drop ratios. There are some exceptional

cases (I) Westfield-1 (-6dB with FMT HO) and (II) Australia Square-2 (Power-10dB), and (III)

Australia Square-3 (Power-6dB), in which both the SDCCH and TCH drop were increased.

From the NMS2000 statistic, most of the improvement was because of the better

TCH_RADIO_FAIL and TCH_RF_OLD_HO counter value. The 2% increasing in SDCCH

drop ratio for the Melbourne Airport has found to cause by higher ABIS failure. Other than

that the NMS2000 statistic has shown to be stable.

Whereas from the walking test measurement results (Graphs 2 and 3), in general, the

outcomes of both Melbourne Airport and Westfield are in better sharp than others. Both

quality and FER stay relative stable after the power reduction as comparing to Australia

Square. The reason is because these buildings are not situated in CBD area and are quite

isolated. Therefore, the interference in these two buildings is much lesser than in Australia

Square.

It is also important to note that the results for Westfield indoor site is due to a combination of

two factors (I) Power Reduction, and (II) Frequency Changed. Westfield-1 has reduced its



SDCCH drop ratio. This is because of the change in BCCH frequency from 76 to 56, which

has resulted in a better UL quality. The 4-dB power reduction does not have any negative

impact on TCH drop call rate on sector 1. The changed of BCCH frequency on sector-1 also

has reduced the adjacent interference on Westfield-2 (BCCH-77). The UL/DL quality has

improved. Therefore, the TCH drop call and SDCCH drop ratios for sector 2 have decreased.

The drop ratios on most Westfield cases excluding 6dB-power reduction, have been

reduced. The reasons may be due to a better link balance as well as the overall quality

improvement on both sectors 1 and 2. However, when the power reduction has increased to

6dB in Westfield-1, the drop ratios have increased due to worsen coverage. Therefore, the

value 6dB is inappropriate for the cell.

For the Australia Square case, after the power reduction for sector 2 and 3 by 10 dB, the DL

quality was affected greatly on Australia Square-2 (Refer to Graphs 4.1 and 4.2)1. On the

other hand, the quality on Australia Square-3 has remained relatively stable as comparing to

the initial benchmarking result. The statistics also shown an improvement in drop ratios for

sector-3 but degrading in sector-2. The improvement in sector-3 can be interpreted as

reducing in signal spillage, in which the TCH_RF_OLD_HO counter has reduced. Whereas in

sector-2, more drop calls (due to TCH_RADIO_FAIL and TCH_RF_OLD_HO ) were

observed because the quality was worsen. By comparing both sector-2 and sector-3, one

can conclude that the initial frequency use by sector-2 is not as clean as sector-3.

The next step was to change the frequency for Australia Square-2 and 3 with 10-power

reduction. An obvious improvement on all areas for Australia Square-2 can be seen.

However, there was a negative impact on the performance of sector-3. Finally the

transmitted power was increased by 4 dB from the originally -10dB for both sector 2 and 3 in

order to improve the quality further. The outcome indicates that the quality, the Drop Call

Ratio and HO Failure were slightly improved(see graphs 4, 5, 6 for complete picture). These

results illustrate that power reduction will only work if and only if the initial frequency is clean.

The Graphs 7 and 8 showing the DL signal distribution for both Australia Square-2 and

Australia Square-3 on different test cases environment.

1 All the quality graphs have excluded the quality class 0 for better viewing on lower class end (Q5, Q6, Q7)Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (33)






Overall, the test cases demonstrate that power reduction can be applied to most of the

indoor sites with an appropriate reduction margin. From the Australia Square test case, it

also proves that the power reduction will only be good if the initial frequency of the cell is

clean. The walking test and NMS statistics will help determine the usable range for the



transmitting power for the indoor site within the acceptable limits of good quality and

performance.

The possible power reduction could be utilised in some cases so that the sectors are

combined to an Omni cell, which provides more capacity with the same number of TRX's.

The attenuation due to combining of antennas is of order 5 dB.



7. FREQUENCY HOPPING

Both frequency and baseband hopping have been implemented and used in indoor cell test

cases. The general observations are improvement in both UL/DL qualities, decreasing in

TCH drop call rates as well as HO failure rate. This section provides details regarding the

implementation, planning and results.

7.1 Commands for Implementing the Frequency Hopping

RF Hopping

ZEBE: 1; GSM: f1&f2&f3&f4&f5&f6&f7&f8; (Create the MA list with 8 frequencies)

ZEQA: BTS= BTS_id: MAL=1; (Attach the MA list)

ZEFS: BCF_number :L; (Lock BCF)

ZEQS: BTS= BTS_id :L; (Lock BTS)

ZEQE: BTS= BTS_id: Hop=RF, HSN1=1; (Define hopping method and the hopping

sequence)

ZEQS: BTS= BTS_id: U; (Unlock the BTS)

ZEFS: BCF_number : U; (Unlock the BCF)

Baseband Hopping

ZEFS: BCF_number :L; (Lock BCF)

ZEQS: BTS= BTS_id :L; (Lock BTS)

ZEQE: BTS= BTS_id: Hop=BB;

ZEQS: BTS= BTS_id: U; (Unlock the BTS)

ZEFS: BCF_number : U; (Unlock the BCF)



7.2 Results and Findings

7.2.1 RF Hopping

The following are the conditions that have been used in choosing the hopping frequencies:

The selected frequency should not cause any problem to surrounding cell,

To simplify the trial, the selected frequency should not be a IUO nor BCCH channel

The reuse condition should be as close to the existing TCH as much as possible,

The selected frequency must fulfil the system requirement e.g. not a co-channel or

adjacent channel to any of its neighbours.

Based on the previous experiences , it is believed that 8 frequencies in RF hopping is the

conservative starting point. As a result, the same approach has been used in the RF hopping

case study.

One important observation from most of walking test measurement (taken from the

Melbourne Airport case) is the frequency hopping can tolerate higher quality class (5-6) while

sustains a good speech quality. Figures 1 and 2 are examples which recorded from same

area in one of the test case building. The same indoor cell serves both. Prior the hopping

implementation, some ‘chopping’ effect on the speech can be heard. But with RF hopping,

the ‘chopping’ effect is no longer existing. This is because in the hopping case, the FER

value is smaller than non-hopping case (Refer to Graph 9-11). The results also show that the

RF Hopping has improved Rx quality, FER and also SQI which is based on the both BER

and FER distributions.

Figure 1: Before RF Hopping implementation



Figure 2: After the RF Hopping implementation





From graph 12, one can observe that the TCH drop call ratio has declined dramatically once

RF hopping is implemented. This improvement is mainly due to the reduction in drop calls

caused by (I) When a TCH transaction ends due to a radio failure (HO failure) on the source

channel during HO attempt (c1014), and (II) Number of TCH releases due to radio failures, in

call setup phase before connection acknowledgement (c1013). However it seems that the

RF hopping cannot improve the SDCCH drop ratio. It is because in this case, the SDCCH is

configured in the BCCH TRX. A small declining in HO failure ratio can be observed from

graph 12 as well. It is suspected that the HO failure ratio is decreasing because the

percentage of HO failure due to the downlink quality is reduced. This analysis proves that RF

hopping has smaller drop ratios than non-hopping case.

The observation from the Chifley Tower case study is slightly different (refer Graph 13).

There are 2 RF hopping test cases for this building and both using 1 MA list with 8

frequencies. The difference between these cases is the use of PC quality thresholds. For test

case 1, the PC threshold Qual DL/UL has been adjusted from 3 to 4 (Table 5). In test case 2,

the value was remained at 3. The reason for changing these parameters is to verify the limit

of hopping case.



Test Case ParameterCurrent

Value

New Proposed

Value

RF(8)-1 HO Threshold Qual DL

PC Threshold Qual DL

4

3

5

4

HO Threshold Qual UL

PC Threshold Qual UL

4

3

5

4

RF(8)-2 HO Threshold Qual DL

PC Threshold Qual DL

4

3

5

3

HO Threshold Qual UL

PC Threshold Qual UL

4

3

5

3

Table 5: PC and HO Threshold Change for Frequency Hopping

The result indicates that the only improvement of using RF hopping is the HO failure ratio.

Other than that, both SDCCH drop ratio and TCH drop call remain similar. The reasons are

(I) the SDCCH was configured in the BCCH TRX, and (II) the existing good indoor quality

(Refer to Graphs 14 and 15). These results indicate RF hopping in this case can not improve

already good starting situation. However, one should paid attention to the drop call due to the

HO failure. The result suggests that the percentage that the calls in bad quality (Q6 & Q7) is

less. As a result, the call drop due to HO drop has reduced.





RF hopping has shown to have a great improvement in the area of speech quality as

compared with the signal strength. However, one improvement idea is proposed in order to

control the use of BCCH TRX and Hopping TRX separately. It is recommended that to have

a separate parameter set for BCCH (non-hopping) and TCH (RF hopping). The following

table illustrates the idea of different parameter sets.

Cases

Parameter

When MS uses non-hopping

TRX (BCCH)

When MS uses hopping

TRX

HO Level Threshold DL -90 -93

HO Quality Threshold DL 4 5 or 6

Table 5: An example of different parameter set for BCCH and TCH TRX in RF hopping cell



7.2.2 BB Hopping

In this case study, an IUO frequency has been used for hopping. The re-use pattern for the

baseband hopping is illustrated in the following table. As can be seen, TRX 3 has very tight

re-use.

TRX no. TRX Type Frequency Re-use Pattern

1 BCCH 18

2 TCH 15

3 TCH 6

Table 6: Frequency re-use pattern for the OCS-22

From the walking test results, no dramatic change has occurred in both DL/UL signal quality

and the serving channels.

From the quality graphs (Refer to following graphs), one can determine how well the OCS

performs when IUO channel has been used for BB-Hopping on OCS-2. The Figures have

clearly demonstrated that the percentage of DL quality for class 0 has slightly decreased,

which is typical for FH. With FH the RXQUAL statistics has to be considered so that the

classes 6 and 7 are paid most attention. The FER and speech quality indicators in TEMS

show improvements with BB hopping. Unfortunately FER is not possible obtain from NMS

2000 statistics.

2 Even the use-pattern is 6, but in actual fact there are 8 frequencies allocate for IUO TRX.Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (46)


The drop ratios for OCS-2 have been divided into three case studies: IUO, non-IUO and BB-

hopping as shown in the following section and the result is tabulated in a chart format. Both

SDCCH and TCH drop ratios remain consistent. The used of BB-hopping in OCS-2 cannot

give any improvement on the SDCCH and TCH drop call ratios. The case here is very similar

to the Chifley Tower in which the existing quality of OCS-2 is already good. Therefore, no

obvious improvement can be observed. But the chart has suggested that BB-hopping has the

lowest HO failure as compared to the others and the non-IUO case has the worst value.

More explanation is given in the later section.



High HO failure (average 45%) excepting BB-hopping case, can be seen on OCS-2. This

high HO failure ratio is mainly due to the congestion on super re-use TRX (see Table 7). The

configuration had in OCS-1 is two regulars and one super TRX and for OCS-2 three regulars

and one super TRX. As a result, it shows in statistics high intra-cell HO failure rate, however

that no handover attempts have been commanded. One possible solution to reduce the HO

failure rate is to increase the Good C/I threshold e.g. from 17dB to 19dB.

Case Super Traffics

(Erlang)

Super Absorption

(%)

HO Failure (%) Super TCH

Block (%)

IUO 2.666 81.424 43.904 56.932

Non IUO - - 61.00 -

Table 7: Some KPI for IUO cell, OCS-2

For the non-IUO case (Abis-tracing purpose), the high HO failure is because of the super-

reuse TRX in BL-US state which has caused an increase in HO failure counter values in

statistics. This occurs because the HO algorithm process does not know the states of the

TRX and due to this it can start HO attempt although the target TRX is locked. Naturally,

there is no HO attempt, but the statistical data contains erroneous data. In order to avoid this

problem, it is recommended that the FRT of the blocked TRX should be regular (FRT=0) until

it is taken into real use.



8. INTELLIGENT UNDERLAY OVERLAY

IUO is a capacity enhancement mainly for outdoor usage, but it is found to be rather useful

for indoors capacity solution as well. From graphs 16-18, the performance of OCS-2 with the

use of IUO is as good as BB-hopping case. In view of tighter frequency reuse, OCS-2 has

proven the usefulness of IUO in indoor planning with the conditions that the indoor cell has

well in building signal isolation as well as clean BCCH channels.

Apart from this, the absorption rate was studied in two ways, by capturing the A-bis data with

a NetHawk protocol analyser and by comparing the real values. The absorption rate (refer to

Table 8) has found to be good in one of our test cases. It demonstrates that the use of super

TRX is efficient.

Date Good C/I Prob. (%) Date Absorption Rate (%)

7th July – Tue 96.7 30th June – Tue 62.53

8th July – Wed 98.0 1st July - Wed 64.95

Table 8: Comparison between the good C/I probability and the actual super TRX absorption rate

The results above depict that there is a big difference between the good C/I probability

measured by Abis-data capturing and absorption rate from NMS2000 statistic. But one

should keep in mind that the good C/I probability for Abis data is determined base on the

time it is stayed on the regular layer. However, in terms of absorption rate on super TRX, it is

calculated when the MS makes an intra-cell HO from regular to super layer if a good C/I

value is obtained, and provided that the MinBsicDecodeTime has been expired. By taking it

into the consideration, one can generalise that the good C/I probability is always smaller than

the absorption rate and proportional to each other. For example, if the normal TCH seizure

time is 30 seconds, the minimum BSIC decoding time is 10 SACCH or 5 seconds and the

good C/I probability in this case is 90%. Then the absorption rate (if only the minimum BSIC

decode time is taken into account) will be 75%. Therefore, the theoretical good C/I probability

above has presented us with a relative good prediction on how well the indoor cells perform.

The positive outcome of this trial is that Abis-data capturing can be used to determine the

efficiency of an IUO in a site without deploying it, providing that correct co-channel or

adjacent channel neighbours are defined in the neighbour list or double BA list (if use).



9. PARAMETER SENSITIVITY STUDIES

9.1 Maintaining the Indoor Traffics

Power Reduction

Power reduction is one of the objectives in this development. Reducing the BTS transmitting

power will shrink the indoor coverage area if the indoor cell is not completely dominating e.g.

Melbourne airport. In order to maintain the traffic within the indoor cell while reducing the

power, some adjustment on the handover threshold parameters is require. The table below

gives the parameters change require for PBGT HO and level threshold HO cases. The value

‘Y’ in the table represents the power reduction value.

ParameterHO

Direction

Current

Value

New

ValueComments

HO Margin

PBGT (PMRG)

Outdoor ->

Indoor

‘X1’ ‘X1-Y’ To make the HO easier from

outdoor to indoor such that the

coverage area remains very much

the same.

HO Margin

Level (LMRG)

Outdoor ->

Indoor

‘X2’ ‘X2-Y’ HO from outdoor to indoor makes

easier, in case of HO causes by

level threshold.

HO Margin

PBGT (PMRG)

Indoor ->

Outdoor

‘X3’ ‘X3+Y’ To make the HO from indoor to

outdoor harder than before. By

doing so, the initial indoor coverage

is maintained.

HO Margin

Level (LMRG)

Indoor ->

Outdoor

‘X4’ ‘X4+Y’ HO from indoor to outdoor harder

when the HO is caused by level

threshold.

Table 9: The HO Parameters Change for Power Reduction with PBGT and Level Threshold HO



Results and Findings

After the implementation of 4dB-power reduction, the traffic of the Airport Term-1 seems to

be declining (Refer Graph 19). The reason for this is the service area of the indoor cell has

been reduced due to the 4dB-power reduction. Initially, it has planned to use the power

budget margin to keep the indoor service area unchanged. However, because of the power

reduction, the field strength for some of the area is below –90dBm. As a result, the number of

HO, which trigger by the HO level threshold downlink is higher than in PBGT (as shown in

Graph 20). In this test case, the parameter LMRG has not been adjusted accordingly.

Effectively, after the implementation, the service area is smaller and the traffic served by the

indoor cell is reduced as well. Graph 20 also show that after the power reduction has been

removed, the number of HO level threshold downlink causes has declined and PBGT

increased to the value as it used to be.



Whereas in the Westfield case study, it shown that the average traffic per day remains more

or less the same. The difference is that the building is closed and indoor cell is dominating,

decreasing of power does not change its situation. Please note the result for Westfield-1

includes the used of both PBGT and FMT HO.

It is also worthwhile to know that the PBGT HO margin can use some extreme value. For

example, the modified margins for PBGT HO has been implemented in the Westside Tower

indoor site as well. The situation in this building is a bit different in which the macrocells are

quite dominant in most of the lobby area. In order to solve this problem, the PBGT HO

margin from macrocells to the indoor cell and from indoor cell to macrocells have been

designated to be –9dB and 19dB respectively. The result from the walking test measurement

has shown to be quite effective. The HO from macro-to indoor and vice versa, have found to

work normal and occur at the appropriate location. However, PBGT HO is not the good

method to be used in this building. The umbrella HO may be a better solution. As with the

HoLevelUmbrella (AUCL), it ensures that the MS will only HO to the indoor cells at a fix value

and no unnecessary camping onto the indoor cells.



Fast Moving Threshold (FMT) Handover

Umbrella and PBGT HO are widely employed in Optus network. Among one of our test

cases, it was decided to employ FMT HO from macrocells to indoor cells of a shopping mall.

The following diagram shows the different scenarios that have been used in this test case.

The two scenarios that will be used are:

1. Power Reduction-xdB with Power Budget HO (NO ACL ),

2. Power Reduction-xdB with FMT and layers define (ACL use),

The following tables contain the list of parameters that required to be changed. The actual

parameter changed can be found in Appendix A.

ParameterCurrent


FMMS

(BSC parameter)

N Y To turn on the fast moving

threshold handover feature.

Fast Moving Threshold

(FMT)

0 8

HO Level Umbrella

(AUCL)

N/A -90

Table 10: The FMT Parameters Change

Parameter HO Current New Comments



Direction Value Value

Adjacent cell

layer (ACL)

Indoor ->

Outdoor

N Upper Define the macrocell (outdoor

cell) as upper layer.

Adjacent cell

layer (ACL)

Outdoor ->

Indoor

N Lower Define the indoor cell as lower

layer.

Adjacent cell

layer (ACL)

Indoor ->

Indoor

N Same Define the indoor and indoor cell

as same layer.

Table 11: Layer Definition for FMT Setting

The following is the MML commands, which have been used for changing the FMMS:

Enabling the FMMS feature

ZWOS:10-25:1;

Disabling the FMMS feature

ZWOS:10-25:0;


From the walking test measurement results with the same route, walked from macro into

indoor coverage area, it illustrates that the MS can handover to indoor cell faster as

comparing to the use of PBGT HO. As a result, it is expected that the traffics in the indoor

cell will increase. Indeed from the NMS2000 measurement, the average traffic on Westfield-1

has increased slightly (Refer to Graph 19 on Page 49). In conclusion, FMT can help to drive

the traffics into the indoor cells.



9.2 Solving In-Lift Drop Calls Problem

Rapid Field Drop (RFD)

RFD is an optional feature, which was tried in order to reduce the number of drop calls in the

lifts. All the parameters that stated below are required to adjust.

ParameterCurrent


Chained_Cell_Usage_P

(BSC parameter)

N Y To turn on the RFD feature.

Threshold level uplink

for rapid field drop

(RPD)

-110 -90 -90dBm has been used in this case

to trigger the RFD HO

Count of successive

rapid field drop

thresholds (CNT)

0 2

CHAIN N Y Enable cell to be chained with the

selected adjacencies for RFD HO

target.

Table 12: Parameters Change for Rapid Field Drop Implementation


The use of rapid field drop in solving the drop calls in the lift is not fully successful. Many

HOs have been noticed during the walking test measurements. From the measurement

results, the number of drop calls in the lifts has reduced after the rapid field drop feature

activated. Nevertheless, some drop calls can still be seen. One of the examples is shown in

the following diagram.



Figure 3: Graphical information illustrates where the drop call occurred

The drop call in this example is because of the bad downlink quality (class 7). One possible

reason for this bad quality is the weak downlink level (see Figure 3). In this case, the rapid

field drop feature will not help. In the next section, another method is introduced for solving

this problem.



10. SEEDING SIGNAL – COUPLER CONNECTION AND CONCEPT

The seeding signal coupler is a device, which is used to couple the sectors with 15-dB

attenuation. It is supposed to ensure handovers in the lift or when the mobile is coming out

from the lift. The picture shows the used couple connections, sector 1 output is connected to

"Input" and the "Output" contains the original signal (L1) and attenuated sector 2 (L2-15).

The sector 2 is connected to "Isolated" and the output to antenna is taken from "-15dB".


By installing the coupler, there will be signal from other sector 15 dB less than the main

server signal. The coupler signal will allow a smoother handover when the signal of the

server become weaker and the other become stronger. The following picture will show how

the handover took place while in the lift:


L1 L2

BTS

Sec. 1 Sec. 2

InputOutput

Isolated -15dB

Couple

L1

L2

L1 + (L2 -15)

L2 + (L1 -15)


Figure 4: HO situation when seeding signal connection was used

After mobile enter the lift (at the dot line marker) the signal was degrading rapidly, so the

handover took place to other sector (at the solid line marker) and the old server signal

become 15 dB lower continue with the current server signal. No drop calls were observed.

However, the result was not very conclusive due to slow moving elevator and stopping on too

many floors along the way. Further testing is required to determine the exact use of the

seeding signal coupler. But at this stage, it looks to be a promising method in solving the lift

problem.



11. FREQUENCY ALLOCATION METHODS

In the Optus Indoor Project, NOKIA Sydney uses the TIM tool for collecting and analysing the

data in determining the channel for a new site. The basic idea behind the method is to do

some kind of walking test measurement in the building. The data is then post-processed and

tabulated into a graph (An example is shown in Graph 21). The most suitable frequencies are

then selected from the available channels by excluding those channels in the graph as well

as their adjacent channels.

For this indoor development project, another tool was used for the frequency allocation

purpose. The TEMS has been employed for scanning all the BCCH channels while walking

in the building. The data was then post-processed and displayed into a graph. The graph

enables us to identify which channel has weak enough field strength so that it will not pose

as a threat as strong co-channel interference, and with weak adjacent channels. PlanEdit is

then use to verify the chosen candidates for any possible co-channel or adjacent channel. A

new candidate may be required if there is a problem. An example of the graph is shown as

the following.



With the use of TEMS method, a new set of channels has been allocated to a number of new

sites as our case studies (Refer to Table 12).

Site Name Parameter Old Value

(Use of TIM)

New Value

(Use of TEMS)

Australia Square-1 BCCH Frequency

(FRQ)

60 62


(FRQ)

76 60


(FRQ)

78 58

O’Connell-2 BCCH Frequency

(FRQ)

75 81

Westside Tower-1 BCCH Frequency

(FRQ)

55 56

Westside Tower-2 BCCH Frequency

(FRQ)

60 79

Table 12: Frequency Change on the indoor sites



Graph 17: DCR/ Frequency Changes

0

5

10

15

20

25

30

Before

After


Graph 23: DCR/Frequency Change


After the changed in BCCH frequency, the drop call ratio (Refer to Graph 22) in most indoor

sites have obviously improved. However, the DCR on O’Connell St-2, BT Tower-2 and

Australia Square-3 have remained quite high. This may probably suggest that the

interference level on this site is high and difficult to find a clean frequency. But overall, the

results show that the frequency allocation method using TEMS is rather good as comparing

to TIM.

In Australia Square-3 case, the reasons for an increasing in DCR are (1) the selected

frequency is not clean, (2) the power reduction conducted on that sector may has caused the

bad quality and result in more drop calls.

Graphs 24 and 25 given the DL signal distribution of both NMS2000 statistic and walking test

measurement results. The walking test results shown more than 95% of the time, the indoor

field strength value is better than –80dBm. Whereas from the NMS2000 statistic, there are

about 5% to 10% of the field strength is worse than –90dBm. This indicates that there may

be some signal spillage because the overspill signal will be at least 10 to 20dB down as

comparing to signal within the indoor. As in BT Tower-2 (or named as Westside Tower-2),

there is about 15% of the signal is less than –90dBm, which may be the reason why the DCR

is high. It is also interesting to note that 90 % of the DL level in 1’Oconnel St-2 (from

NMS2000 statistic) is better than –70dBm. This indicates that most of the traffic is inside the

building. However, the DCR has remained high after the frequency change. The explanation



for this is the interference level in high rise floors is quite severe in this building and it is

difficult to allocate a clean frequency for that cell.

From the observation above, one can conclude that the performance of the in building is very

much depending on the environment. Among all the test cases, the performance of in-

building for Melbourne Airport, Paramatta Westfield and OCS building are generally better

than other high rise buildings. Both Melbourne Airport and Westfield are low buildings which

is less vulnerable to interference as comparing to the high rise buildings. Apart from this, they

are quite isolated and not in the CBD area. As a result, the frequency allocation for these

sites is easier and cleaner. Similarly, OCS building is not quite within the CBD area. Thus,

the performance is expected to be better.

The advantage of TEMS over the TIM is it enables the user to scan all the frequencies

needed. On the other hand, TIM can only pick up those frequencies, which are defined in the

neighbour list if double BA list is not in use. As a result, the data collect from TIM may not

contain all the necessary information in deciding channels for a new site.



12. TRAFFIC ABSORPTION MEASUREMENT

Three buildings have been selected for this case study . The following are the sample results

from 1’Oconnell building, Westside Tower and Chifley Tower. The results are calculated from

the average of 4 days traffic statistics in 24 hours. From the graph, Nx and NAx are showing

the xth neighbour traffic profile before and after the integration of indoor site. Please note the

ordering of the neighbour is from the strongest to the weakest.

Traffic absorption measurement result for 1’Oconnell indoor cells

Indoor traffic and Absorbed traffic

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

Indoor traffic Absorbed traffic

Idoor traffic, each sector

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

Sector1 Sector2

Neighbor cell traffic before and after indoor cell inplemented

0.0

2.0

4.0

6.0

8.0

10.0

1 3 5 7 9

11

13

15

17

19

21

23

N1 NA1


0.02.04.06.08.0

10.012.014.0

1 3 5 7 9 11 13 15 17 19 21 23

N2 NA2


0.0

5.0

10.0

15.0

1 3 5 7 9 11 13 15 17 19 21 23

N3 NA3


0.02.04.06.08.0

10.012.014.0

1 3 5 7 9 11 13

15

17

19

21

23

N4 NA4



Traffic absorption measurement result for Westside Tower indoor cells

Indoor traffic and Absorbed traffic

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

Indoor traffic Absorbted traffic


0.0

0.2

0.4

0.6

0.8

1.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

Sector1 Sector2


0.0

2.0

4.0

6.0

8.0

10.0

1 3 5 7 9

11 13 15 17 19 21 23

N1 NA1


0.0

1.0

2.0

3.0

4.0

5.0

6.0

1 3 5 7 9 11 13 15 17 19 21 23

N2 NA2




0.01.02.03.0

4.05.06.07.0

1 3 5 7 9 11 13 15 17 19 21 23

N3 NA3


0.0

5.0

10.0

15.0

20.0

1 3 5 7 9 11 13 15 17 19 21 23

N4 NA4


0.0

2.0

4.0

6.0

8.0

10.0

12.0

1 3 5 7 9 11 13 15 17 19 21 23

N5 NA5


0.0

2.0

4.0

6.0

8.0

10.0

1 3 5 7 9 11 13 15 17 19 21 23

N6 NA6


0.0

0.5

1.0

1.5

2.0

1 3 5 7 9

11 13 15 17 19 21 23

N7 NA7



Traffic absorption measurement result for Chifley Tower indoor cells


0.0

0.5

1.0

1.5

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

Sector1


0.0

2.0

4.0

6.0

8.0

10.0

12.0

1 3 5 7 9

11 13 15 17 19 21 23

N1 NA1


0.0

2.0

4.0

6.0

8.0

10.0

1 3 5 7 9 11 13 15 17 19 21 23

N2 NA2




0.0

2.0

4.0

6.0

8.0

10.0

12.0

1 3 5 7 9 11

13

15

17

19

21

23

N3 NA3

One of the Westside Tower indoor site’s neighbours, N5, has shown to have a big increasing

in traffics after the site has been integrated. The only explanation is some big events have

taken place in that area which caused a sudden increase of traffic during that week.

Ideally, it is expected some of the neighbour cells traffic will be reduced after the indoor cell

is integrated. But the results have provided us a different indication. These results have

illustrated that the impact of the indoor cells have on the traffic absorption of neighbour

macrocells is small. But the question is “Where the indoor traffic coming from”. Some

possibilities are listed below:

The indoor cell has its own traffic. In a sense, the indoor cells can generate more traffic

because of better quality and coverage has been offered.



The traffic may be coming from other macrocells which are not include in the neighbour

list.

Increasing in the number of Optus subscribers.

From the Graph 29, there is an obvious immediate increase of 3 to 10% traffic within a week

period. Under this circumstance, the possibility of the indoor cells stimulate more traffic into

the network is more substantial. Some examples of why better indoor coverage and quality

can generate traffic are (1) Increasing in the number of mobile terminal calls, (II) coverage is

provided to the black spot area like basement car parks, and (III) the indoor cells have eased

the blocking rate of the macrocells, and therefore more traffic can be seen.

The following table illustrates a comparison between the actual indoor traffic and the traffic

prediction uses by NOKIA Sydney. The method uses in the prediction is based on the

calculation of 10% out of the total building tenants with each subscribes uses 15mErlang.

Building Prediction Real Data week 36

Chifley Tower 9 1.53

1’Oconnell 5.25 1.46

Westside Tower 2.48 1.49

Australia Square 3.75 2.43

NRMA Building 15 2.75

Table 13: A comparison between the real indoor traffic and the prediction



As can see, the real indoor traffic for Chifley Tower, NRMA and 1’Oconnell St buildings is

conflicted to the prediction. The reasons are (1) In Chifley Tower which was a Telstra design,

no antenna has been installed for the low-rise floors (G-L10), (2)NRMA Building is still under

construction, many tenants have yet to move in, and (3) In 1’Oconnell Building, more people

have moved out. As a result, the number of actual tenants in the building is far less than the

initial assumption.



13. INTERFERENCE BETWEEN INDOOR SITES

For this case study, two buildings, Australia Square and 1’Oconnell in the Sydney CBD area

have been selected. The distance between these two buildings is approximately 200m with

direct LOS for the top half floors of the buildings.

The Australia Square indoor cells have to be defined as the neighbour of 1’Oconnell and vice

versa. The TEMS has been used to measure the field strength of 1’Oconnell indoor cells

from Australia Square. However, no 1’Oconnell signal was detected. On the hand, the BSIC

of the same frequency was measured. As a result, no interference was measured between

the selected sites. In conclusion, two indoor sites with a distance of 200m will not cause any

interference problem even the same frequency is shared between them.

14. CASE STUDIES EVALUATION

Indoor Frequency Allocation Alternative

From the frequency allocation case study, it is found to be quite difficult to allocate a good

frequency because of the tight re-use pattern. An alternative solution is to reserve a

frequency for the indoor system.

The indoor interference testing has shown that the interference level between indoor cells is

small (has proven within a distance of 200m). As a result, with a dedicate channel for indoor

system, one can expect a good indoor quality for the indoor cells. Apart of this, higher

trunking efficiency can be obtain by having only just one sector (configuration 3+0) for the

indoor site instead of having a configuration of 1+1+1.

If higher capacity is required, two sectors can be employed. Since the area on high rise

levels are more vulnerable to interference as comparing to the lower levels. One can use the

dedicate frequency on the high rise sector and the normal BCCH channel is then use on the

low rise sector. If not possible of having the dedicate channel, the microcell frequency can be

used as the indoor channel as well.



Indoor Design Improvement

By combining the indoor cells, the frequency hopping can then be used to improve the indoor

quality. However, combining the indoor cells will introduce a loss of 5dB (for a 3 way splitter).

A booster may be used to compensate the loss.

With the improvement in antenna developments, polarised antennas like circulate antennas

can be employed to gain extra field strength. Higher radiating elements can be used as well

to provide higher power and thus can provide cheaper indoor system.

Call Drops in Lifts

During measurement in relating to the drop calls in lift problem, it was noticed that more call

drops were occurred while the lift travelling upward as comparing to the downward direction.

Due to the time constraint, no concrete information and explanation can be presented.



15. CONCLUSION

The overall Indoor Solution Development project has been conducted successfully. Most of

the objectives have been achieved and few require further development.

The traffic measurement case study has given a different in sight into the traffic behaviour

after the indoor site was integrated. The result demonstrated that the indoor cell generates

more traffic to the network. This is attributed to the improved coverage and quality inside the

building. The cases show an immediate increase of traffic between 3 to 10% in overall

network area. While overall area traffic was increased, 20% of the outdoor cells have traffic

absorbed by the new in-building cells. 80% of them shown that the indoor cell generate traffic

without removing any traffic from the original network.

In regarding to the RF isolation between two in-building sites, the 200m separation case

confirmed that frequency re-use between these two building is possible. Further testing with

building pair closer to each other is recommended.

In general, the Fishbone Distributed Antennae System cases have delivered a dominant

coverage throughout the building. It is also noted that multiple sector in-building sites are

showing high call drop rate in the upper sectors compared to the bottom sector or a single

sector building. Further investigation is needed to minimise these call drops. This could be

caused by signal leakage to adjacent building, interference or lift call drop problems.

The visibility to all interfering cells in the network has found to be critical for the correct

frequency planning of the indoor cells. This can be achieved by TEMS frequency scanning

function or other common measurement tool like NMS/X, TIM with Double BA list active in

the network.

The power reduction case studies have presented a vital information i.e. the power reduction

will only work if and only if the initial frequency of the cell is clean such that even the C/I

value is reduced, the calls can still be maintained. In Paramatta Westfield shopping mall, the

result has turned out to be positive in which the drop call ratio was reduced. In this case, it is

suspected that the power reduction has improved the link balance. Better SDCCH and TCH

drop can be observed as well in most of the Australia Square cases. It is suspected the

signal spillage was minimised by the use of power reduction. However, the power reduction Document Number/Version © 1997 Nokia Telecommunications Oy PageB8S 056047AE/0.0.2 (73)


may result in weakening cell performance if it is not govern by proper planning. For example

in the Melbourne Airport case, the indoor traffic absorption has declined because the HO

level margin (LMRG) has not justified to the power reduction value, which caused cell

coverage shrunk.

The use of FMT HO (Westfield Paramatta) has stopped the Ping-Pong HO problem as

comparing to PBGT HO. The case studies have also shown that the FMT HO can help to

drive the traffic into the indoor cells.

Initial evaluation on the use of Seeded Signal concept in solving the lifts drop calls has

depicted a positive outcome. The Rapid Field Drop handover function also delivered some

improvement to the situation. However, the Seeded Signal concept is believed to be a better

solution for removing the problem. Because of the limited trial in this project, further field trial

is recommended. An alternative solution is the standard GSM Call Re-establishment

function.

FH has found to be an effective tool for indoor solution. It improves the DCR as well as the

quality, which has been proven in the Melbourne Airport case. But in the situation where the

initial in-buildings have good performance (like Chifley Tower and OCS building), FH will not

deliver any noticeable improvement to the cells.

The used of IUO in OCS-2 has presented a good overall cell performance. It demonstrates

that IUO is a good indoor solution because it enables a tighter frequency reuse while

maintaining the cell performance. However, IUO is only good for indoor environment

providing that the in building has a good RF isolation, and clean BCCH channel. For effective

use of IUO, it is also important that the building is a high capacity site.

This project called for the support of Optus and global Nokia resources. The rare opportunity

of testing in a live network ensured that real network behaviour was captured and analysed.

The expertise input of Optus also ensured the maximum benefit was drawn from the

investment of Nokia resources. Nokia would like to thank Optus for this opportunity.



16. REFERENCES

[1] “Indoor Planning and Solutions – Ver. 8.0”, Paul Yap

[2] “Frequency Hopping in NOKIA BSS – Ver. 0.1”, Mika Kahkola

[3] “RF Power Control and HO Algorithm – CAN22744”, Electronic Library

[4] NED, BSC S6 ETSI



APPENDIX A: Actual Parameters Changed in FMT HO Case Study

Changes that used in both PBGT and FMT

Parameter change: BTS Power Control Parameters

Indoor

Cell

Parameter Current

Value

New Proposed

value

Parramatta

Westfield-1

BTS Max.

Transmit Power

(PMAX)

max-0 max-4

Parramatta

Westfield-2

BTS Max.

Transmit Power

(PMAX)

max-0 max-4

Parramatta

Westfield-3

BTS Max.

Transmit Power

(PMAX)

max-0 max-4

Parameter change: BTS Adjacencies for Parramatta Westfield-1Site Name Parameter Indoor cell -> Outdoor

cellCurrent Value

New Proposed

Value

Reason

Parramatta Westfield-1

HO Margin Level (LMRG)

Parramatta Westfield-1 -> Parramatta Ran-2

3 7 Make the HO from indoor to macro difficult



Parramatta Westfield-1 -> Parramatta Stadium-2




Parramatta Westfield-1 -> Parramatta-3



cellCurrent Value

New Proposed

Value

Reason
















cellCurrent Value

New Proposed

Value

Reason



Parramatta Westfield-3 -> Parramatta Gasworks-3








Parramatta Westfield-3 ->Parramatta Stadium-2






Changes that will be used in PBGT HO


cellCurrent Value

New Proposed

Value

Reason


HO Margin PBGT (PMRG)












cellCurrent Value

New Proposed Value

Reason














cellCurrent Value

New Proposed Value

Reason



















Parameter change: BTS Adjacencies for Parramatta Stadium-2

Site Name Parameter Outdoor cell -> Indoor cell

Current Value

New Proposed

Value

Reason

Parramatta Stadium-2

HO Margin PBGT

(PMRG)

Parramatta Stadium-2 -> Parramatta Westfield-1

6 2 Make the HO from macro to indoor easier


HO Margin PBGT

(PMRG)


3 -1 Make the HO from macro to indoor easier


HO Margin PBGT

(PMRG)



Parameter change: BTS Adjacencies for Parramatta Gasworks-3


Current Value

New Proposed

Value

Reason

Parramatta Gasworks-3

HO Margin PBGT

(PMRG)

Parramatta Gasworks-3 -> Parramatta Westfield-3


Parameter change: BTS Adjacencies for Parramatta-3


Current Value

New Proposed

Value

Reason

Paramatta-3 HO Margin PBGT

(PMRG)

Paramatta-3 -> Paramatta Westfield 1

6 2 Make the HO from macro to indoor

easierParamatta-3 HO Margin

PBGT (PMRG)



easierParamatta-3 HO Margin

PBGT (PMRG)



easier



Changes that will be used in FMT

Parameter change: BSC configuration

BSC Name Parameter Current

Value

New Proposed

value

Reason Testing Method

Sydney BSC-9 FMMS 0 1 To enable the Fast

Moving MS handling

in Macro cell

Walking test and

OMC statistic

Parameter change: BTS Adjacencies for Parramatta Westfield-1Site Name Parameter Indoor cell ->

Outdoor cellCurrent Value

New Proposed

Value

Reason


Adjacent cell layer (ACL)


NU UPPER To define the different cell layer







Parramatta Westfield-1 ->Parramatta Westfield-2

NU SAME To define the different cell layer



Parramatta Westfield-1 -> Parramatta Westfield-3








New Proposed

Value

Reason




NU UL To define the different cell layer







Parramatta Westfield-2 ->Parramatta Westfield-1














New Proposed

Value

Reason

























Parameter change: BTS Adjacencies for Parramatta StadiumSite Name Parameter Outdoor cell

-> Indoor cellCurrent Value

New Proposed

Value

Reason


Adjacent Cell Layer (ACL)


NU LOWER Define layer structure










HO Level Umbrella (AUCL)


n/a -90dBm -




n/a -90dBm -




n/a -90dBm -


Fast Moving Threshold (FMT)


0 8 -




0 8 -




0 8 -



Parameter change: BTS Adjacencies for Parramatta Gasworks-3Site Name Parameter Outdoor cell


New Proposed

Value

Reason

Parramatta

Gasworks-3




Parramatta

Gasworks-3



n/a -90dBm -

Parramatta

Gasworks-3



0 8 -

Parameter change: BTS Adjacencies for Parramatta-3Site Name Parameter Outdoor ->

Indoor CellCurrent Value

New Proposed

Value

Reason

Paramatta-3 Adjacent Cell

Layer (ACL)


NU LOWER Define layer

structure


Layer (ACL)



structure


Layer (ACL)



structure

Paramatta-3 HO Level

Umbrella (AUCL)


N/a -90dBm -


Umbrella (AUCL)


N/a -90dBm -


Umbrella (AUCL)


N/a -90dBm -

Paramatta-3 Fast Moving Threshold (FMT)


0 8 -



0 8 -



0 8 -



Parameter change: BTS Adjacencies for Parramatta Ran-2Site Name Parameter Outdoor cell


New Proposed

Value

Reason

Parramatta

Ran-2


Parramatta Ran-2 -> Parramatta Westfield-1


Parramatta

Ran-2




Parramatta

Ran-2




Parramatta

Ran-2



n/a -90dBm -

Parramatta

Ran-2



n/a -90dBm -

Parramatta

Ran-2



n/a -90dBm -

Parramatta

Ran-2



0 8 -

Parramatta

Ran-2



0 8 -

Parramatta

Ran-2



0 8 -



APPENDIX B: Sample Power Budget Calculation and Antennae Layout










Documents

Optus Indoor Solution