Companies are looking up to wireless Wan

Wireless Wans may soon be the answer for companies looking for a cheap, fast and easy solution to setting up their own...

Wireless Wans may soon be the answer for companies looking for a cheap, fast and easy solution to setting up their own communications networks.

Wireless local area networks have been around for some time, but opportunities for creating wireless wide area networks, operating over distances of more than a few dozen metres, are only just beginning to arise.

A WWan can be defined as a network allowing data transmission by satellite or radio between different buildings situated hundreds of metres or more apart. The sites connect with each other or through a central network through antennae installed on the buildings. WWans can be much cheaper than traditional networks, more flexible and easier to install.

WWans have been in use for some time among very large companies such as IBM and communications carriers, but they have recently become an option for mainstream commercial organisations.

"We rarely get asked about WWans," said Ian Keene, an analyst at Gartner.

"It is only in the past six months that people have been exploring the concept," said Dave Swift, solutions marketing director at Alcatel.

Wide area wireless transmissions can be implemented on a point-to-point basis or in a networked many-point-to-many-point environment. The term WWan is used to describe both types of infrastructure.

WWans can be implemented by adapting a wireless Lan; using unlicensed radio frequencies; using more powerful licensed radio frequencies; through satellite transmissions or through a combination of these technologies with traditional wired technologies.

"Many of our customers move seamlessly from Wi-Fi to WWan and back to the corporate networks via a VPN channel," said Shelly Julien, vice-president of Netmotion Wireless. Three years ago, Netmotion introduced software called Mobility, which is designed to provide transparency of operation to the user.

For wireless data transmissions over a greater range than the few metres covered by wireless Lans, "The main option is in the 2.4GHz or 5GHz ranges, which are based on 802 standards," said Maurice Philpott, an analyst at Ovum. Transmissions taking place at 2.4GHz or 5GHz radio frequency provide data throughputs of a maximum 11mbps and 54mbps respectively.

This is much faster than the services offered by the cellular radio companies using 2.5G (GPRS) or 3G (UTMS) mobile phone networks. With these, the maximum available speed is 144kbps, and the user typically gets a lot less. And it is more than 10 times faster than the services possible with 2G (GSM) mobile phone networks, which are essentially restricted to niche applications such as SMS.

The 2.4GHz and 5GHz transmissions are made according to standards set by the IEEE. The standard governing 2.4GHz transmissions is 802.11b, which is widely promoted under the name Wi-Fi. The standard governing 5GHz transmissions, which has only just come into use, is 802.11g.

You do not need a licence to create a network using these standards. "The technology is relatively standardised so you can get economies of scale. Suppliers are making equipment with prices comparable to DSL products," said Philpott.

Theoretically, point-to-point 802.11 connections can cover distances of up to 25 miles, but the power needed to span that range is outside statutory electromagnetic radiation limits.

Typically, said Ged Fitton, systems engineering manager at Cisco, 802.11b wireless bridges span a range of between two and five miles. With 802.11g transmissions, "You could probably do a point-to-point connection over seven to 12 miles."

You can also create networks using IEEE 802.11 technology. "This is attractive for organisations such as councils that own a lot of buildings," said Swift.

"You give your employees 802.11b phones and you have a solution that bypasses traditional carriers." "I know about half a dozen councils doing that," said Alan Wright, wireless technology consultant at Cable & Wireless subsidiary ALLnet.

However, the 802.11 transmissions are unlicensed so potentially, you could get interference from another device. Another problem is that the throughput provided may not be sufficient.

If a company needs either more bandwidth than provided by Wi-Fi, or transmissions over a greater distance than a few miles, another option is to use licensed microwave radio frequencies.

These frequencies start at just above the unlicensed range at 7.5GHz, and go upwards: typical frequencies are 11GHz or 13GHz. This gives transmission rates of 100mbps and upwards - well above those provided by 802.11.

Microwave transmissions are regulated by the Radiocommunications Authority, a government body that deals with the radio spectrum and has responsibility for assigning fixed terrestrial point-to-point links. Constitutionally it is an executive agency of the DTI and one of the bodies scheduled to become part of industry watchdog Ofcom, probably at the end of 2003.

Wright sees microwave as a cost-effective alternative to cable-based transmissions using dial-up, ISDN or leased lines. "They are quicker than leased lines and more cost-effective than Lan extension services. The outlay is up-front and the customer then owns the bandwidth. The revenue costs are basically what the Radiocommunications Authority charges."

Cable & Wireless was the contractor for the Lancashire Police WWan as reported in Computer Weekly (19 September 2002). This network replaced an ISDN network, and connects 55 police sites using a 155mbps backbone. The annual licence fee charged by the Radiocommunications Authority for this network is £55,000.

Kep Simcox, project manager, said, "We anticipate a 5% to 10% saving over a 10-year period when compared with the alternatives. We will also save on infrastructure costs as the only changes will be the replacement of radio links between stations."

An even more powerful network implemented by Cheshire County Council was reported in the 8 April issue of Computer Weekly. It provided up to 620 mbps using microwave frequencies ranging up to 38GHz.

"Even though the start-up costs were higher, we have gone for radio technology as it will be much cheaper over five years," said Mike Tuck, head of ICT planning at Cheshire County Council.

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