The panacea of corporate networking has to be wireless. It has no messy cabling ducts, no costly upgrades, and should you need to move location, you simply pack away all the antennae, PCs and servers and install them in your shiny new offices.
There are two types of wireless network: the ad hoc and the peer-to-peer. Both are based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, but the ad hoc networks consist of a central access point from which any PC in range and with an antenna can connect to the network. The peer-to-peer network is a simple point-to-point connection between two computers.
The most crucial thing needed for a wireless network to function is the access point. This is the small radio transmitter responsible for dispersing the data, usually across a radius of no more than 150ft.
A remote device uses a transmitter to pick up this data. Usually, a wireless network is based around laptop computers, with the antenna connecting neatly into the PC-card slot. Workstations can be connected through a PCI PCMCIA cradle card.
In most cases, the access point is connected to the wired backbone. This allows seemingly unconnected devices to gain quick and easy access to all LAN resources and existing internet connections.
There are two types of access point: software and hardware. The hardware access point is a dedicated device that sits in a strategic place within an office. This is by far the most popular type of device.
The software access point refers to a standard computer that has an antennae installed but which is loaded with the necessary gateway software to handle the amount of data coming through from the varied devices.
LAN of hope and glory
There are many situations where a wireless LAN would be preferable. The most obvious, and probably the most successful, is in the warehousing industry.
A large open space, where employees do not spend much time in any one place, is an ideal environment, as the open space means there would be no problems in coverage.
But this is not the only situation where a wireless network comes into its own. "Most wireless networking is deployed building-to-building, as has always been the case, and LAN-to-LAN," said Paul Munnery, managing director at CNP.
"Generally, wireless has higher bandwidth and lower cost, compared with either a leased line or laying fibre. In the UK, 60 to 70 per cent of all wireless networks operate building-to-building," he added.
Bernard Picot, managing director at Proxim Europe, said: "A wireless LAN will suit all customers who rely on mobility, temporary installations or significant scalability and flexibility in an office or corporate environment."
IP phones that work over wireless networks can be an ideal solution for hospitals where mobile phones are not allowed because of sensitive equipment. Patient information can be entered from any ward.
They are also ideal for temporary network installations and tricky installations in old or listed buildings. But they do have drawbacks.
Speed, a crucial sticking point
One issue is speed. The original IEEE 802.11 standard specified data rates of up to 2Mbps. However, the real throughput of only 1-1.5Mbps was often far too low to tempt network managers from copper.
But the latest standard now allows for speeds of up to 11Mbps. Products based on this standard started to ship towards the end of last year, but it still does not seem fast enough in a world where 100Mbps is comparatively old hat, and everyone is talking about gigabit Ethernet.
In fact, 11Mbps of throughput is ample for most networking needs. It may not provide your users with seamless video conferencing quality, but for most end-users, this is more than sufficient.
Despite this, a new standard that will replace direct sequence spread spectrum (DSSS) next year will disperse any previous worries about throughput.
"The new OFDM wireless LAN products will operate at 5.3/5.7Ghz and will be available from early next year," said Munnery. "Initially delivering up to 54Mbps and then 100Mbps within nine months or so, this will effectively be fast Ethernet networking."
Another problem is interoperability. For such a small market there are a huge number of companies offering wireless products. "Interoperability is still not a reality," said Munnery. "Most 2.4Ghz wireless LAN vendors are telling us they are working towards open interoperability. But none of them are busting a gut to achieve it."
Picot agreed. "Scalability is more strategic than basic interoperability. As a response to this concern, we have designed our Harmony product as a modular architecture able to mix several standards," he said.
The IEEE has specified two standards for data transmission within the 802.11 standard, known as frequency hopping spread spectrum and DSSS. Although both offer the same sort of functionality, there are interoperability issues between the two. But the Wireless Ethernet Compatibility Alliance started work earlier this year on the Wi-Fi interoperability standard.
Now, any system bearing the Wi-Fi logo is guaranteed to work with any other bearing the same mark.
Another issue is with roaming from one access point to another, to cover more than one floor in an office block with a wireless LAN, for example. There is no official standard within 802.11 to clarify the roaming method, so one vendor's access point will not always successfully hand you over to another.
Blue in tooth and claw
Also, rightly or wrongly, the public's perception of wireless technology is that it is far less secure than data travelling neatly along a wire.
It would be easier to spy on wireless data, but even if you managed to pick up a signal, decoding it would be an entirely different matter. Unlike most traffic in UK LANs, wireless data is encrypted.
Another wireless standard that has emerged in the last 12 months is Bluetooth. Although recommended for consumer use, Bluetooth could still be of great interest to the corporate world. A travelling employee, for example, would be able to send email from his laptop via a mobile phone, without taking the phone out of his pocket.
Although the data rates are slow compared with its 802.11 cousin, Bluetooth will be sufficient for most purposes, although some experts believe it causes interference with the 802.11 standard. A wireless network could be the answer to many problems. Remote workers could arrive at the office, take out a laptop and log directly into the corporate network without cables, outlets or even desks. Total cost of ownership is greatly reduced.
Munnery is convinced that wireless networking is increasingly taking market share away from conventional cabling. "The future looks very bright indeed," he said.
SPREAD ACROSS THE BAND
Spread spectrum technology (SST) uses far more bandwidth than is required to send signals, so it can overcome noise and multi-path problems. The best systems deliver 11Mbps and use 22Mhz of spectrum. That translates to a maximum of only 44Mbps if the entire 2.4Ghz band is used. The best possible speed is about 15Mbps in 22Mhz, which means that SST is approaching its limits.
Orthogonal frequency division multiplexing (OFDM) technology breaks one high-speed data signal into tens or hundreds of lower speed signals, all transmitted in parallel.
This creates a system highly tolerant to noise and, at the same time, very efficient in its use of bandwidth. Noise and multi-path immunity allow for wide area, multipoint coverage, and the efficient use of bandwidth allows for more high-speed channels in a frequency band. The main difficulties in narrow band and spread spectrum are overcome by OFDM.
Vendor Wi-Lan has developed W-OFDM, another version of OFDM, which further improves its characteristics.
The signal reception is corrected for distortions, allowing more transmission speeds. It can also increase range.
While OFDM has been acknowledged as a very efficient technology, it has always proved difficult to implement. Advances in digital signal processors now permit OFDM systems to be cost-effectively constructed, creating renewed interest.
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