Wireless Wireless CommunicationCommunication

Learning Objectives:Learning Objectives:By the end of this topic you should be able to:By the end of this topic you should be able to:

describe describe wireless communication methodswireless communication methods, ,

describe describe typical applicationstypical applications of wireless communications, of wireless communications,

describe the describe the advantages & disadvantagesadvantages & disadvantages of wireless of wireless communications.communications.

TaskTask

Using ‘study buddies’ :

1.1.Write down Write down two communications two communications technologiestechnologies that don’t use cables that don’t use cables

[30 sec][30 sec]

2.2.ExchangeExchange with another group and add with another group and add your two to their list (if yours are your two to their list (if yours are different)different) [30 sec][30 sec]

3.3.ContinueContinue until your list returns until your list returns [2 [2 mins]mins]

Wireless TechnologiesWireless Technologies All All opticaloptical technologies: technologies:

infra red, fibre optic, lasersinfra red, fibre optic, lasers

Wi-FiWi-Fi 802.11802.11

BluetoothBluetooth

mobile ‘phonemobile ‘phone GSM, GPRS, 3GGSM, GPRS, 3G

satellitesatellite

BluetoothBluetooth uses uses radio wavesradio waves to tansmit data to tansmit data range of a Bluetooth device range of a Bluetooth device ~10m~10m,,

very weak signals of 1 milliwatt (‘phones ~ 3 watts)very weak signals of 1 milliwatt (‘phones ~ 3 watts) bandwidth bandwidth ~2Mbps~2Mbps

proposed proposed Bluetooth 3.0Bluetooth 3.0 protocol protocol 480 Mbps480 Mbps bandwith bandwith auto-detection of other Bluetooth devicesauto-detection of other Bluetooth devices

no expertise required - makes its own connectionsno expertise required - makes its own connections Bluetooth Bluetooth headsetheadset connection to mobile ‘phone connection to mobile ‘phone

‘‘hands-free’ callshands-free’ calls use use mobile ‘phone as modemmobile ‘phone as modem for laptop computer for laptop computer transfer filestransfer files between devices between devices

images, MP3s, etc between ‘phones, PDAs and computers, images, MP3s, etc between ‘phones, PDAs and computers,

BluetoothBluetooth

AdvantagesAdvantages widely availablewidely available

on portable deviceson portable devices

doesn’t require line of sightdoesn’t require line of sight pass key can be usedpass key can be used

to prevent non-authorised to prevent non-authorised devices connectingdevices connecting

DisadvantagesDisadvantages low bandwidthlow bandwidth

slow transfer of dataslow transfer of data

10m maximum range10m maximum range only connect to one device only connect to one device

at a timeat a time can’t use headset as well as can’t use headset as well as

laptop connected to mobile laptop connected to mobile ‘phone‘phone

Wi-FiWi-Fi most common wireless networking,most common wireless networking,

most laptops already come with a WiFi card built in most laptops already come with a WiFi card built in uses radio waves to transmit datauses radio waves to transmit data also known as also known as 802.11802.11 wireless protocol wireless protocol

3 main variants: 802.113 main variants: 802.11bb, 802.11, 802.11gg, 802.11, 802.11nn computers can be up to 100 feet apartcomputers can be up to 100 feet apart bandwidth from 10Mbps (802.11b) to 54Mbps (802.11g)bandwidth from 10Mbps (802.11b) to 54Mbps (802.11g)

802.11n will give bandwidth >200Mbps (& greater distance)802.11n will give bandwidth >200Mbps (& greater distance) need need wireless access pointwireless access point connected to network connected to network

wireless card automatically detects & connects to access point wireless card automatically detects & connects to access point a network connection will be established.a network connection will be established.

Wi-FiWi-FiTypical applications:Typical applications: connect laptopsconnect laptops to an organisations network to an organisations network

most laptops most laptops already come with a wireless NICalready come with a wireless NIC built in built in laptops connecting to the Internet using laptops connecting to the Internet using wireless ‘hotspots’wireless ‘hotspots’

Internet cafés, hotels, pubs, airports, train stationsInternet cafés, hotels, pubs, airports, train stations laptops connecting to laptops connecting to home networkshome networks

to enable to enable sharingsharing of Internet connection, printers, music …. of Internet connection, printers, music …. PCs with wireless NICs able to connect to a networkPCs with wireless NICs able to connect to a network

where cabling would be expensive or difficultwhere cabling would be expensive or difficult to install to install mobile ‘phones & PDAs able to access the Internetmobile ‘phones & PDAs able to access the Internet

without using expensive mobile data tariffs (charged per Mb)without using expensive mobile data tariffs (charged per Mb) printers (& games consoles) connected to wireless networkprinters (& games consoles) connected to wireless network

Wi-FiWi-FiAdvantagesAdvantages

no need to use no need to use cablescables portable devices not limited to one portable devices not limited to one

locationlocation for network for network allows allows ad-hoc networkingad-hoc networking network reaches network reaches outdoorsoutdoors

social/corporate social/corporate eventsevents

no line of sightno line of sight required required no expensive mobile datano expensive mobile data bandwidth sufficientbandwidth sufficient for Internet for Internet

communicationcommunication worldwide worldwide standardstandard

any laptop can connect to any wireless any laptop can connect to any wireless networknetwork

DisadvantagesDisadvantages bandwidth restricivebandwidth restricive for some for some

network communicationsnetwork communications especially with especially with many usersmany users multimedia streamingmultimedia streaming videoconferencingvideoconferencing

restrictedrestricted rangerange (~30m) (~30m) securitysecurity issues issues

susceptible to susceptible to hackinghacking WEP keyWEP key required to access required to access

signal strength signal strength affected by walls, interference …affected by walls, interference …