The basics of wireless networking

Brian Nadel ZDNet US

Published: 06 Feb 2003

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Currently there are three wireless-networking standards competing for your airtime. Wi-Fi (802.11b) is the corporate choice and has a suitably wide range for use in big office spaces. 802.11a offers bigger bandwidth and fewer interference problems but a shorter range. Bluetooth is meant for short-range, temporary networking in conference rooms, schools or homes. In addition to the detailed rundowns below, check out our side-by-side comparison of these different technologies with traditional, wired Ethernet.

Networking solutions
	Pros	Cons	Approximate range	Max. / typical data speeds
Ethernet	inexpensive; included on most new PCs; hundreds of hardware makers	requires cabling; larger networks need hubs and switches	91m (300 feet) per segment	100 / 60Mbps (for 100Mbps network)
Wi-Fi (802.11b)	relatively inexpensive; dozens of manufacturers; WECA certification; radios integrated on new notebooks	data speeds inadequate for high-end multimedia; 3 channels	30m (100 feet)	11 / 5.5Mbps
Wi-Fi5 (802.11a)	high bandwidth for multiple users or multimedia distribution; 8 channels	expensive; small number of manufacturers	15m (50 feet)	54 / 22Mbps
Bluetooth	very cheap for integrated radio on handheld or cellphone; widespread installation; low power	low data throughput; short range; lack of compatibility	6-15m (20-50 feet)	723 / 300Kbps

Wi-Fi reigns supreme

Wi-Fi is currently the most popular and least expensive wireless LAN specification. It operates in the 2.4GHz radio spectrum and can transmit data at speeds up to 11Mbps within a 30m range. Its balance of economy, bandwidth, and particularly range have made it the dominant standard for business, and many employees have taken the technology home with them for work and family computing. The Wireless Ethernet Compatibility Alliance (WECA) has done its part by certifying hundreds of products to make sure they work together. But Wi-Fi has a couple of drawbacks. It shares airspace with cellphones, Bluetooth, security radios and other devices, so it's vulnerable to interference. And because of data-transfer overhead and the inevitable wall or other transmission obstacle, its real throughput is closer to 5Mbps, or about half of its specification.

802.11a: new kid on the block

A recent arrival, 802.11a, has a couple of advantages over Wi-Fi. It runs at a less-populated frequency (5.15GHz to 5.35GHz) and is therefore less prone to interference. Its bandwidth is much higher, at a theoretical peak of 54Mbps. Even though actual throughput is closer to 22Mbps, it still offers a lot more elbow-room than Wi-Fi does for transferring high-quality digital audio and video or other large files across the network, as well as for sharing a broadband connection. And some manufacturers offer proprietary modes that can push throughput a little higher. Its main problem is its shorter range: 15m compared to Wi-Fi's 30m, forcing you to buy more access points to ensure full coverage. At the moment, 802.11a equipment is also more expensive than Wi-Fi, although the price gap is narrowing steadily. Since November 2002, WECA has been certifying 802.11a products, which carry the organization's new Wi-Fi Certified capabilities label.

Because Wi-Fi and 802.11a use different radio technologies and portions of the spectrum, they are incompatible with one another. However, dual-standard equipment is currently available, which makes switching back and forth surprisingly simple. Still, if you want to make a choice between the two and stick to it, consider these factors: if you already use one or the other standard at your business, you should probably use the same one at home to make telecommuting easier. If compatibility and price are not issues, 802.11a's better performance could be worth the extra expense. But if you need to cover a lot of ground cheaply, Wi-Fi is the more efficient choice.

Bluetooth: the personal touch

Named after a tenth-century Danish king, Bluetooth is a somewhat different standard from Wi-Fi or 802.11a, offering much more flexibility but on a smaller, 'personal area network' scale. Its actual throughput is only 300Kbps, and its range around 10m. But unlike Wi-Fi and 802.11a, which require adapters, routers, gateways, access points and synchronised setup schemes to connect devices, any devices with a Bluetooth radio and antennae can speak to each other with little or no preparation.

Bluetooth is also poised to replace infrared ports as the instant-transfer mode of choice, with better range and no line-of-sight requirement. Meeting attendees can immediately transfer files between their Bluetooth-equipped notebooks across a conference table, or they can send a file to a Bluetooth-equipped printer without downloading drivers. Bluetooth-equipped kiosks in airports and coffee houses let you log on to the Internet through your laptop or handheld. Bluetooth will soon be standard equipment on many cellphones and handheld computers. There's even talk of putting Bluetooth into home appliances.

But for all the theoretical benefits of Bluetooth, the reality is that it's currently a mess of incompatible hardware and software. And because Bluetooth and Wi-Fi occupy the same frequency range, they can eat into each other's bandwidth and reduce throughput by 10 percent or more.

What lies ahead

This alphabet soup of standards will get even more complicated over the next few years, as upcoming standards come to market. For instance, 802.11g promises to increase Wi-Fi bandwidth to 54Mbps (22Mbps in practice), while 802.11i will plug some of the security holes in the WEP protocol. A new Bluetooth specification will operate at a higher frequency, yielding twice its present bandwidth.

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