Wireless:Wireless: Solution for high-speed Internet access Solution for high-speed Internet access

in regional Queenslandin regional Queensland

Wireless:Wireless: Solution for high-speed Internet access Solution for high-speed Internet access

in regional Queenslandin regional Queensland

Presenter: Mr. Huan Pham (PhD student)

Supervised by Dr. Bill Lavery

James Cook University

Internet Access PlatformsInternet Access PlatformsInternet Access PlatformsInternet Access Platforms

Twisted pair

Coax/Fibre

Optical Fibre

Wireless

• Cable modem

•Tel modem•ISDN•xDSL

•FTTH•Fibre ring

•MMDS•LMDS

•Satellite

Internet

xDSL modem

xDSL modem

ISDN adapter

Telephone modem

Exchange

ISP

Twisted PairTwisted PairTwisted PairTwisted Pair

Twisted Pair CapacityTwisted Pair CapacityTwisted Pair CapacityTwisted Pair Capacity

Telephone modem < 64 Kbit/s (for download, lower for upload)

ISDN Basic 128 Kbit/s, (bi-directional)

xDSL Symmetrical or Asymmetrical Maximum download rate from 1.5 Mbit/s to 50 Mbit/s depending

on the technology and distance. Upload rate for asymmetrical case: dozens Kbit/s

Distance limit: < 5 km from CO or Remote access terminal Access capacity not shared by other users.

Coax/Fibre cableCoax/Fibre cableCoax/Fibre cableCoax/Fibre cable

Internet

Cable Modem

ISP

NIU

Fibre Node

Cable Modem

NIU

Fibre Node

Coaxial Cable

Optical Fibre

Coax/Fibre CapacityCoax/Fibre CapacityCoax/Fibre CapacityCoax/Fibre Capacity

Downstream up to 30 Mbit/s Upload up to 10 Mbit/s Bit rate is shared among subscribers passed by

coax cable. --> bit rate/user is lower

Wireline advantages/disadvantagesWireline advantages/disadvantagesWireline advantages/disadvantagesWireline advantages/disadvantages

Advantages Potentially offer very high bit rate More reliable (less affected by noise, interference,

weather conditions) Disadvantages

High up-front investment in cabling, environment issues, permission to lay cable...

Much higher cost per user in low population density areas

Higher deployment time Monopoly by cabling companies

Wireless OptionsWireless OptionsWireless OptionsWireless Options

MMDS (and other WLL operating at 2 - 5 MHz)

LMDS (Local Multipoint Distribution Services)

Satellite

Mobile

MMDSMMDSMMDSMMDS

Main transmitter

Repeater

Internet Point of Presence

MMDSMMDSMMDSMMDS

Frequency 2.1 GHz, 2.3 GHz (in Australia) Line of sight transmission Not vulnerable to rain Maximum coverage distance = 50 km Normally one way - telephone cable return Two-way MMDS is more costly and limited by available

bandwidth Bandwidth is shared among all (online) users Frequency reuse can be made by using n-sector antennas,

and/or cellular layout (the latter is subject to ACA regulation)

MMDS CapacityMMDS CapacityMMDS CapacityMMDS Capacity

Assumptions:MMDS Channel: 6MHz

Modulation scheme: QAM-64

Customer peak offered rate: 400 (Kbit/s)

Statistical multiplexing gain: 5

User time online: 20%

Capacity:Number of users (one sector):

Number of users (four sectors): 4 x 2000 = 8000

2000)/(400%20

5)/(30

sKbit

sMbit

30Mbit/s

Other Frequency OptionsOther Frequency OptionsOther Frequency OptionsOther Frequency Options

2 x 150 MHz frequency at 3.4 GHz band. (this is to

be auctioned later this year)

Unlicensed frequency band at 2.4 GHz and 5GHz

LMDSLMDSLMDSLMDS

Frequency: 28 GHz Strict line-of-sight transmission Signal absorbed by rain (See Signal in Rain graph) Cellular layout. Cell size (<5 km) mainly depends on:

transmitter power modulation scheme rain rate required availability

Frequency reuse made possible by n-sector antennas cellular layout cross-polarisation transmission

LMDS CapabilityLMDS CapabilityLMDS CapabilityLMDS Capability

AssumptionsBandwidth 2x75 (MHz)

Modulation scheme QAM-16

Frequency reuse factor/cell: 4

Cell size (square): 5(km) x 5(km)

CapacityBit rate / cell: 400 (Mbit/s)(able to support about 1000s online users, peak rate a couple of Mbit/s)

Bit rate / km2: 16 Mbit/s/km2

~100 Mbit/s each way

LMDS Hexagon layoutLMDS Hexagon layoutLMDS Hexagon layoutLMDS Hexagon layout

Frequency reusefactor = 4

Frequency reusefactor = 3

LMDS Square LayoutLMDS Square LayoutLMDS Square LayoutLMDS Square Layout

Frequency reusefactor = 1

Frequency reusefactor = 2

Frequency reusefactor = 4

SatelliteSatelliteSatelliteSatellite

Web server

Internet

Satellite

ISP

Satellite CapabilitySatellite CapabilitySatellite CapabilitySatellite Capability

Satellite operates at C-band (4-8GHz) or Ku-band (12-

18GHz) which is affected by weather condition.

Large coverage areas, virtually anywhere.

It’s difficult to apply frequency reuse. Thus it offers limited

bit rate/user.

Commonly available with one-way Internet access, return

via telephone modem. Typically 400Kbit/s download

Suits non real-time applications

Suitable for areas where other options are not available

SummarySummarySummarySummary Advantages of Wireless over Wireline

Scalability Lower up-front investment Fast deployment time Ability to bypass the incumbent Telco.

Limitations Limited bandwidth Affected by noise, interference, weather conditions Latency of satellite systems limit real-time applications

The advantages make them suitable for low density population areas in regional Queensland such as Townsville & Carne.

Current ResearchCurrent ResearchCurrent ResearchCurrent Research

Performance of TCP over wireless and...

How to facilitate QoS (Quality of Service) over

wireless link

Questions?Questions?Questions?Questions?

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