Types of Broadband

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

compare different types of broadband connection and give suitable situations where the use of each would be appropriate

Types of Broadband connectionNeed to be able to describe:• asymmetric digital subscriber line (ADSL),

• cable,

• wireless,

• leased line,

• satellite

Hunter’s Hints:

• Where am I?

• What am I doing?

• How fast do I need to do it?

Dial up Internet• legacy Internet connection method

– 1 in 6 households still using dial-up Internet access (in 2011)!

• uses telephone line• modem required to connect to computer

– converts digital signals into analogue sounds (and vice versa)

Dial up Internet

Dial up Internet• legacy Internet connection method

– 1 in 6 households still using dial-up Internet access (in 2011)!

• uses telephone line• modem required to connect computer to telephone line

– converts digital signals into analogue sounds (and vice versa)

• 56kbps theoretical maximum bandwidth– 1% of current UK average broadband speed (i.e. 100x slower)

ADSL Broadband• most common domestic broadband connection

‒ 99% UK coverage

• uses existing copper telephone line– telephone can be used at the same time as Internet connection

requires ADSL filters to be installed in ‘phone sockets

• router required to connect ADSL to computer– router is often also a wireless access point

• 24Mbps theoretical maximum bandwidth• average UK broadband speed 6 Mbps (in 2011)

– bandwidth variation due to: • distance from telephone exchange,

• age/quality of telephone line,

• contention ratio….

ADSL BroadbandMerits:• uses existing telephone line

– no extra installation of cable is required = no extra cost

– popular for domestic installation

• coverage: 99% availability in UK

• ADSL provides an ‘always on' Internet access – telephone can be used at the same time

ADSL BroadbandDrawbacks:• needs to be connected to a telephone exchange within a

workable distance (~6km)– not possible for remote locations

ADSL Bandwidth v Distance

ADSL BroadbandDrawbacks:

• needs to be connected to a telephone exchange within a workable distance (~6km)– not possible for remote locations

• Asymmetric: upstream bandwidth is less than downstream – takes longer to upload an image than to download

– takes longer send an email with attachments than to receive

• high contention ratio– available bandwidth shared between connected users

– can be up to 50:1 ratio (more users = less bandwidth per user)

• electrical interference on the telephone line– other devices connected to the telephone line

• fax machines, cordless ‘phones

Leased Line• connection exists between two locations only

– customer & ISP

• a dedicated bandwidth service – delivered over a leased fibre connection

• preferred by large businesses and organisations – providing access into their own networks using an extranet

Leased LineMerits:

• there are no contention ratios – direct connection between one router and another router

– this means the bandwidth is guaranteed

• leased lines are symmetric (DSL), – same amount of upstream bandwidth available as downstream bandwidth

• unlike ADSL

– essential for streaming media content providers (TV, radio, music)

• secure & private network connection– dedicated exclusively to the customer

Drawbacks:

• the line is installed especially for an organisation – makes leased lines very expensive

Wireless Broadband• aka: mobile broadband

• 3G data on mobile telephone networks

• can use laptop, mobile ‘phone, tablet computer

• access wireless broadband by connecting computer:– through a mobile ‘phone using Bluetooth (‘tethering’),

alternatively use a USB cable,

– using a USB modem stick (dongle).

Wireless BroadbandMerits:• can be online while not at home or when travelling• can get broadband in areas where there are no fixed

line connections• theoretical bandwidth of 14Mbps

– most providers claiming up to 6Mbps UK average bandwidth 1.5Mbps (2011)

• relatively high bandwidth Internet connections– potentially fast downloading of images, apps …..

– sufficient bandwidth to enable video calls

Wireless BroadbandDrawbacks:• needs a good 3G signal to be available

– not all areas have 3G access

• bandwidth currently often very low– slow access to data & downloads

– ‘jerky’ video calls & media streaming

• can be expensive compared to ADSL:– ~£1 per GB of data for limited contract

– cost of additional usage can be high (especially abroad)

• download/usage limits can be restrictive – not designed for heavy users

Cable Broadband• main infrastructure uses fibre-optic links

– coaxial copper cable connects a local cabinet to the home• some movement towards Fibre to the Home (FTTH)

Cable Broadband

Cable Broadband

Cable Broadband

Cable Broadband• main infrastructure uses fibre-optic links

– to connect ISP to local distribution cabinet (‘green box’)

• copper cable connects a local cabinet to the home– some movement towards Fibre to the Home (FTTH)

• Internet access often provided by cable TV companies– e.g. Virgin Media (cables already installed)

• higher bandwidths than ADSL are possible– up to 100 Mbps available for UK home users.

theoretical bandwidth of Gbps (1Gbps = 1000Mbps) ‘future-proofing’ bandwidth provision?

Satellite Broadband

Satellite Broadband

Satellite Broadband

Satellite Broadband• uses satellite dish to transmit & receive data

– to/from telecommunications satellites in orbit above the Earth

• satellites are in geostationary orbit– move at the same speed as Earth rotation

– always over the same point of the Earth

• data transmitted & received using microwaves

Satellite BroadbandMerits:• can be used in remote areas

– where physical or wireless connections are not available

Satellite BroadbandDrawbacks:• cost of hardware & installation is expensive

– + subscription £50pm for 10Mbps+ data cap limits

• a delay between data being sent and received (0.7s)– problem for real-time communication:

• video conferencing, remote surgery …

• high contention ratios– decrease in available bandwidth at peak times

• asymmetric – downstream has a higher bandwidth than upstream

uploads much slower than downloads (like ADSL)

Bandwidth

Communications Bandwidth

Broadband (ADSL) up to 24Mbps

Cable up to 100Mbps

Wireless (3G) 7Mbps

Satellite 10Mbps

Leased Line (DSL) up to 1Gbps

June 2011 Q9All members of a Mountain Rescue Team based in a town in the Peak District team are volunteers, living across a wide area including some remote locations.

Not all team members have broadband Internet access.

A member of the team, who lives in a remote location, has been offered a broadband internet connection.

Compare ADSL to a satellite connection for accessing the Internet. [3]

Mark Schemeavailability ADSL requires the user needs to be within a certain distance from a compatible local exchange whereas a satellite connection can be used in remote areas where physical and wireless connections are not available

connection type ADSL is uses copper cable to connect whereas a satellite connection relies upon microwaves

bandwidth ADSL offers sufficient bandwidth (Mb/s) to allow more data to be sent at the same time meaning large volumes of data can be handled at once whereas a satellite connection has a much lower bandwidth (Kb/s) meaning lower volumes of data can be sent at any one time

multimedia ADSL can handle simultaneous data and audio streaming whereas a satellite connection would mean multimedia files suffer delays and stoppages during their presentation on screen

symmetry both ADSL and satellite are asymmetric meaning downstream has a much higher bandwidth than upstream