Chitamu & Mwakabaga5th International Confernence on Open Access1 The Impact of Radio Channel...

Chitamu & Mwakabaga 5th International Confernence on Open Access 1

The Impact of Radio Channel Variability on Broadband Throughput Rates in Different Parts of Tanzania

byPeter Chitamu and Teddy Mwakabaga

Centre for Telecommunications Access and ServicesSchool of Electrical & Information Eng.

The University of the Witwatersrand, JohannesburgTel: +27 11 717 7216

Email: [email protected]: http://www.ee.wits.ac.za/comms/

School of Electrical and Information Engineering

University of the Witwatersrand, Johannesburg

5th International Conference on Open AccessParadise Holiday Resort, Bagamoyo, Tanzania 14-16 November 2007


Outline• Introduction• Problem statement

– Underlying network capabilities for ICT Services

– Prevailing conditions in Tanzania– System Modelling

• Results and Discussions • Summary & Conclusions


ICT ServicesWhat has

Changed?


Connectivity Challenges• ICT services require different underlying

network capabilities– Capacity (Number of simultaneous

connections)– Reach / Coverage – Throughput (bps)

• Other considerations based on above– Transmission errors– Connection delays (Network latency)


Multimedia Connectivity for the new User

PSTNPSTNPSTNPSTN

InternetInternet(IPnet)(IPnet)

InternetInternet(IPnet)(IPnet)

Multi-Multi-ServicServic

eeNetNet

Multi-Multi-ServicServic

eeNetNet

Fax

PersonalPersonalMultimedia GatewayMultimedia Gateway

Global Global ConnectivityConnectivity

&&ContentContent

DistributionDistribution ??

Residential or SOHOMonitoringMonitoring

StationStation


Fixed-Mobile Access Fixed-Mobile Access Configurations ExampleConfigurations Example

802.1x Hot Spot802.1x Hot SpotOperatorNetwork

Tele-WorkingSOHO


Convergence (Integrated) Services

TelematicsTelematics

TelematicsTelematics,,Info Services,Info Services,Point of SalePoint of Sale

EmailEmail

W W WW W WFile transfer,File transfer,MultimediaMultimedia

0.10.1 11 1010 100100 10001000 kbyteskbytes

1010

100100

1,0001,000

10,00010,000

100,000100,000

Data volume per subscriber / busy hourData volume per subscriber / busy hour

Sub

scrib

ers

per

cell

Sub

scrib

ers

per

cell

TelematicsTelematics

TelematicsTelematics,,Info Services,Info Services,Point of SalePoint of Sale

EmailEmail

W W WW W WFile transfer,File transfer,MultimediaMultimedia

0.10.1 11 1010 100100 10001000 kbyteskbytes

1010

100100

1,0001,000

10,00010,000

100,000100,000

Data volume per subscriber / busy hourData volume per subscriber / busy hour

Sub

scrib

ers

per

cell

Sub

scrib

ers

per

cell

IP is trying to tie together all these different servicesIP is trying to tie together all these different services

ICT Services require a flexible network to cope with wide ranging requirements


ProvidedProvidedServiceService

FDD FDD especiallyespeciallySuited forSuited for

SymmetricalSymmetricalServices andServices and

Wide areaWide areacoveragecoverage

TDD TDD especiallyespeciallySuited forSuited for

AsymmetricalAsymmetricalServices andServices and

small areasmall areacoveragecoverage

FDD / TDDFDD / TDD

10 kbps10 kbps 100 kbps100 kbps 1 Mbps1 Mbps 10 Mbps10 Mbps

VoiceVoice

E-mailE-mail

Data Base AccessData Base AccessInformation ServicesInformation Services

Tele-bankingTele-bankingFinancial ServicesFinancial Services

Video ConferencingVideo Conferencing

Electronic NewspaperElectronic NewspaperImages / SoundfilesImages / Soundfiles

Tele-shoppingTele-shopping

Video TelephonyVideo Telephony

Question: Who needs what ?Question: Who needs what ?


Lea Skorin-Kapov, etal,”Analysis of End-to-End QoS for Networked Virtual Reality Services in UMTS”, IEEE Comms. Mag. April 2004, pp. 49-55

Main Classification is Error and Latency Tolerance


Telecomms. Connectivity Major Events

Voice on PSTNData on PDSNBroadcasting

Fixed-Line

1986

Fixed-LineMobile (1G)(More fixed)

1991

Fixed-LineMobile (1G & 2G)(Fixed declining)

Voice on PSTNVoice on 1GData on PDSNBroadcasting

Inter-workingPSTN & PDSN(Packet & Circuit Switching)Broadcasting

2002

Fixed-LineMobile (2G & 3G)(More Mobile)

ConvergencePSTN & PDSNBroadcasting(Limited)

All-IP2006

Separate Voice from Data Paradigm Multimedia Communication

Fixed & MobileConvergence


ProblemStatement


What is the problem?• Coverage

– Different operating areas impose different coverage requirements

– For low density users and hilly areas, operators has to build many sites to meet coverage requirements which increases cost of service provision

• Data Rates– Achievable data rates in an area are directly

linked to the quality of the reception


Problem: How to guarantee high data rates over large coverage area

50% ofPeak Rate

80% ofPeak Rate

20% ofPeak Rate

DistanceBTS


As Dec 2002As Dec 2002

M El-Sayed and J Jaffe, ”A View of Telecomms. Network Evolution”, IEEE Comms. Mag., Dec 2002, pp. 74-81


SystemModelling


Understanding of operating environments in Tanzania

• Propagation measurement campaign carried out – Path loss models in representative areas of Tanzania– Multipath delay spread– Dense Urban, Urban, Sub-Urban, and Rural

• This information used to investigate how operating environment will impact on the currently broadband access networks– iBurst, cdma2000 EV-DO and UMTS - HSDPA


Link Budget vs Data RatePT(max)

PT(min)

PR(max)

PR(min)

Distance

bRb TPE

R

W

N

P

WNR

P

NE R

R

O

b

DynamicRange

Quality of Received Signal


Example: Propagation Environments

Mombo

Soni Ngudu, Mwanza

Njombe


Operating Environments make certain technologies very expensive to use outside Cities


Scatter Plots


Multipath selected Results

LU1162.LIN

-2.0 1.0 4.0 7.0 10.0 13.0 16.0 19.0 22.0 25.0 28.0MICROSECONDS

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Volts

-6 dB


Multipath selected ResultsAR1082.LIN

-3.0 2.0 7.0 12.0 17.0 22.0 27.0 32.0 37.0 42.0 47.0 52.0MICROSECONDS

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Volts

-6 dB


Multipath selected ResultsAR1092.IMP

- 0 . 0 0 0 0 1 0 0 . 0 0 0 0 1 0 0 . 0 0 0 0 3 0 0 . 0 0 0 0 5 0 0 . 0 0 0 0 7 0

- 0 . 2

0 . 0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

1 . 2

Time in seconds

Pre-Cursors and Post-cursors

Nearby echos and a group from far


Average path loss profiles

• Flat terrain with light vegetation (e.g. Mwanza)

• Undulating landscape, with moderate vegetation (e.g. Njombe, Iringa, many parts of Morogoro)

• Hilly and heavily forested (Lushoto, USA River)

PL(d) [dB] = PL(do) + 10 nMF log(d/do) + σ

dBdPL 1log4267 10

dBdPL 3log5388 10

dBdPL 5log7293 10


Results&

Discussions


Assumptions• Networks not loaded to influence coverage• Use average path loss models from

propagation measurements• Target BER of at least 10-6 for data rate of

500 kbps and 1.5 Mbps• No link improvements through diversity,

adaptive modulation, etc• Only physical network speed as influenced

by Eb/No specification and no flow or error control mechanisms applied


Impact of Data Rate Variability

Gain Due to Change in Data Rate

-12

-10

-8

-6

-4

-2

0

0 200 400 600 800 1000 1200

Data Rate (kbps)

Gai

n [

dB

]


EV-DO at 800 MHz

-160

-140

-120

-100

-80

-60

-40

-20

1 2 3 4 5 6 7 8 9 10 11 12

Distance [km]

Re

ce

ive

d s

ign

al

[dB

m]

Flat Terrain Undulating Hilly

Free Space 500 kbps 1.5 Mbps


iBurst at 1790 MHz

-180

-160

-140

-120

-100

-80

-60

-40

-20

1 2 3 4 5 6 7 8 9 10 11 12

Distance [km]

Re

ce

ive

d s

ign

al

[dB

m]




HSDPA at 2100 MHz

-180

-160

-140

-120

-100

-80

-60

-40

-20

1 2 3 4 5 6 7 8 9 10 11 12

Distance [km]

Re

ce

ive

d s

ign

al

[dB

m]




Summary• To make ICT Services widely accessible, the issue of

connectivity platforms needs to be carefully considered– Tanzanian market is cost conscious

• Understanding of the operating environments enable network designers to optimised Coverage, Capacity and throughput to meet the requirements for the wide range of ICT services

• Tanzania operating environment are mostly coverage limited with users in undulating and hilly terrain.– More work needs to be done to understand how operating

environments influence both cost and type of ICT services that can be cost-effectively offered in different areas of Tanzania

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