Broadband: Move faster forward

With all that in mind, why would anyone want to get involved in the sad debacle that is broadband at present? The answer is that it’s not just ADSL and not just BT that are on offer.

In Britain, we still have ISDN and, of course, that old stalwart, leased line. And as our buyer’s guide this month explains, on top of that there are terrestrial and satellite wireless services to be considered as broadband options.

Add cable modem technologies from the two principal cable operators, and it soon becomes apparent that companies looking to get hold of broadband do not necessarily have to go with BT.

Technical hitches

However, problems still arise when it comes to getting broadband services.

ADSL, the most widespread broadband platform in the UK, has suffered its fair share of technical hitches and still continues to be available only to the lucky few who work or reside within 5.5km of a BT exchange.

The rollout of ADSL services has been dictated by BT, and the process of local loop unbundling (LLU) is expensive and complex for the ex-state monopoly’s rivals, which have angrily complained to Oftel about the barriers erected by BT to other telcos gaining access to its exchange equipment.

Cable is slightly cheaper than ADSL but accounts for only around 15 per cent of the whole broadband market. It is limited because it is only available to users in specific locations where the cable has already been upgraded to broadband.

Another option is terrestrial wireless, which is also limited to a few locations in Britain. A satellite link can be installed almost anywhere but is a bit more expensive.

Thinking about the link

In this buyer’s guide we have attempted to give as much information as possible about the different companies and the technology and services they offer. When a business is contemplating getting broadband, it has to consider several issues. Cost is probably the most important, but, as you get what you pay for, it is important to consider what the link is to be used for.

If you have plans for web and email hosting, which require a fast uplink, then it would be wise to consider a leased line or symmetric DSL (SDSL), which works like ADSL but has equal download and upload data rates. Terrestrial wireless is also a possibility here, as the transfer speed of the uplink can be increased.

ADSL and cable are suitable for companies that will be downloading more data than uploading.

Before you can make a choice, you need to consider with care the technology and how it works. We’ll explain the differences between each technology in this guide.


ADSL – Asymmetric Digital Subscriber Line – is the main rival to cable modems in the UK. ADSL works by pushing data down a single copper telephone line that has been divided into two parts: one for voice and the other for data. A DSL modem filters out the higher frequencies used for data exchange, leaving the voice part of the line intact and working as normal.

The main drawback with ADSL is that the service gets worse the further the end of the telephone line is from the exchange. Originally, subscribers had to be within 3.5km of an exchange but better technology, such as rate-adaptive DSL modems, has increased the working radius to 5.5km.

The technology was originally designed by BT to transmit video pictures over ordinary copper phone lines – so-called video-on-demand (VoD). However, the technology turned out to be as capable of sending data packets to subscribers.

There are several versions of ADSL, but the most used is Discrete Multitone (DMT). This has many individual channels operating at different frequencies transmitting and receiving data in 4Kbps blocks. If one frequency is blocked because of interference, the DSL modem will stop using that particular channel but continues to work effectively because it loses only a small part of available bandwidth.

ADSL can work at speeds of up to 8Mbps in the downlink and 1Mbps in the uplink, although economic reasons mean that almost all ADSL providers offer much slower speeds than these. ADSL has an advantage over other technologies, as it has an almost universal infrastructure already in place.

Cable modemsA cable modem works by reserving part of the radio spectrum it pipes into homes and offices for data transmission.

This radio spectrum is nearly a gigahertz wide and is normally used to fit in hundreds of digital television channels. Each channel band or multiplex is capable of delivering data at around 30Mbps.

This is normally divided up between around 50 users who share the local repeater – the big green boxes in the street – which provides them with television and data services. Each user is capped at 512Kbps in the downlink and 128Kbps in the uplink.

Earlier versions of cable modems differ from their modern counterparts as they didn’t use cable in this way, and were more akin to ordinary modems piggybacking on the telephone network provided by the cable operators.

Cable modems are only offered by cable operators within their franchise areas. Choice is further limited by the age of the cable system, as some areas still need upgrading before broadband services become available.

At present, cable passes around 13 million homes and offices in the UK.

In Europe, a cable modem is generally the cheapest method of getting a broadband service and in America it is the most popular.

SatelliteSatellite as a method of broadband delivery is fast gaining ground in Europe. The idea is much the same as with cable in that the satellite uses a part of the radio spectrum or transponder to send data to a dish antenna.

The satellite acts as a ‘mirror’ between the user and the satellite provider’s internet gateway. The antenna is part of a remote terminal that connects the satellite link to the user’s network.

Unlike earlier systems that used a normal telephone line as the return path to the satellite company’s gateway, the antenna sends data back up to the satellite itself. These gateways look like a point of presence from a data networking perspective.

Satellite networking solves the availability and reach problem for a large portion of the population, but for the most part traditional satellite suffers from fundamental problems of high cost and low performance.

The round trip time (RTT) of signals sent via satellite is typically around half a second. This RTT can degrade performance with the TCP/IP protocol, which was originally designed for low-latency networks.

Modern systems use a range of methods, such as local caching and TCP/IP optimisation, to overcome problems of latency and slow-start, which makes satellite a much more viable proposition.

Wireless broadband

On the ground, wireless broadband services use a variant of wireless Lan technology to transmit data through the air. This works by means of an antenna fixed on top of a building pointing towards a central base station owned by the wireless company. This transceiver works on a microwave frequency and at the subscriber’s end radio waves are converted back into Ethernet packets. These radio waves are normally in the 3.6 to 4.2GHz range.

Speeds go up to 1Mbps but the main drawback is that service is restricted to a few areas in the UK at present. But, like satellite, it has the advantage of not needing any infrastructure in place between the subscriber and the service provider.

While the rollout of microwave-based broadband continues apace, things still look shaky for fixed wireless in the 28GHz and 40GHz range. Not only is the government having problems finding anyone interested in buying the remaining licences, but many experts believe that the spectrum allocated is wholly inadequate for people and businesses in rural areas.

This is because not only are they too far away from their local exchange for ADSL, but they would be too far away from any wireless base station as well.


A survey by the Communications Management Association reported that out of 2000 business users of telco services, more than 70 per cent said they would like to use broadband services and found their competitiveness was suffering because they did not have access to the technology.

The government plans to put some £30m into regional broadband facilities. Regional development agencies and administrators will have access to the funds and have been asked to put forward “innovative schemes” to extend broadband networks.

The money will be distributed to regions that lack a proper broadband service. Scotland, Wales, East Anglia, the south west and Yorkshire will get the majority of the cash. This may help rectify the situation whereby the UK has the fewest broadband users of all the major economies, as well as service providers that are among the most costly. The two problems could, of course, be related.

E-minister Douglas Alexander recently announced that the government would spend the money to “boost the delivery of fast internet services through broadband technology to all parts of the UK.”

This promise follows a damning report by the Broadband Stakeholders Group, which concluded that Britain would still be no more than a middle-ranking broadband nation by 2005 despite the government aiming to make the country the most competitive one by that time.

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