The ideal situation of universal-coverage wireless broadband is not here, and may never be achieved. In any case, it will not always be convenient or economical to use 3G or (eventually) 4G wireless in all mobile working situations. Today's wireless technologies provide a patchwork of connectivity that can do different jobs in different situations, so you'll probably end up deploying a selection. Here's a tour of what's available.
There are three broad divisions into which wireless technologies can be grouped: PANs (Personal Area Networks) that provide short-range connectivity; LANs (Local Area Networks) that provide connectivity at the scale of local offices or public hot-spots; and WANs (Wide Area Networks), which -- as the name suggests -- span wide geographical zones. All current high-speed radio data networks are inherently short range, so the difference between LANs and WANs is more a question of what services are supported rather than any particular technical difference.
When evaluating any wireless system, be sure to consider upfront and ongoing costs (which can be difficult to predict accurately unless explicit promises are extracted from service providers) as well as security, compatibility with third-party service providers (especially in different territories) and the roadmap for future enhancements.
Wireless PANs
Wireless PANs are suitable for the area immediately around the desk or within the vicinity of the mobile worker. The most common current example of a PAN technology is Bluetooth, although infrared can also be thought of as a PAN. In the future, ZigBee and ultrawideband (UWB) will add some quite different options to the mix.
Infrared is the longest-serving wireless technology of them all. Its range is limited and uniquely it requires a 'line of sight' between the receiving and transmitting devices. Household remote controls use infrared. It is also built into many notebooks, handhelds and mobile phones, and is an option for connecting portable equipment to dial-up connectivity. Infrared is also used to 'beam' data between handhelds, and to link portable equipment to printers. It's not very reliable, not very fast and not very desirable. Use it if nothing else is available.
Bluetooth comes in three flavours -- Class 1, Class 2 and Class 3 -- offering theoretical maximum ranges of 100, 30 and 10 metres respectively. The 1mW Class 3 Bluetooth with 10m range is the most common, although the achievable range in any environment can be reduced by factors like other nearby wireless services, plus walls, ceilings, furniture or people between the network nodes. Bluetooth shares the 2.4GHz band with 802.11b/g wireless LANs and ZigBee.
Bluetooth has now reached version 2.0, which has an Enhanced Data Rate of 2.1Mbps, compared to the 723.1Kbps of version 1.x, with which it is backwards-compatible.
Bluetooth is integrated into many notebooks and handhelds, and quite a few mobile phones. If it's not present, it can be added via a USB adapter or an SD card (the latter is appropriate for handhelds, which lack support for USB Bluetooth adapters). Bluetooth adapters are also available that work over serial and other more obscure interfaces, so you may be able to wirelessly connect some legacy devices.
Bluetooth is designed for short-range cable-replacement applications. Examples include using a mobile phone as a modem for a notebook computer, linking a mobile phone to a handsfree headset, or a handheld to a GPS receiver, and sending data to a printer.
ZigBee is a medium-range, low-power and low-speed network designed primarily for industrial and domestic control. It has yet to be widely deployed, but is expected to make its first appearance in IT in peripherals such as keyboards, mice and remote controls. It is mentioned here for its potential to cause and be caused interference with other systems such as 802.11b/g and Bluetooth, with which it shares the 2.4GHz band.
Ultrawideband is the newest radio technology to enter service. Still under development, it is low range, low power and very high speed. It is not confined to any particular band, but spreads its signal over many gigahertz, relying on the extreme spread and very low power to avoid interfering with those other services with which it collides. Specifications are not finalised, but it will probably offer up to around 400Mbps within around five to ten metres and will first come to light in consumer electronics as a replacement for video and audio wired connections. IT use is expected to include automated backup, high-bandwidth links for synchronisation of large data sets and storage connectivity applications.
Wireless LANs
Wireless LANs are appropriate for communication over office-, home- or campus-sized areas. They are promoted by the Wi-Fi Alliance, Wi-Fi being a generic name for a collection of WLAN standards that vary in data transfer speed and range.
Wi-Fi also provides public access to the Internet in locations such as transport nodes (airports, railway stations), city hotels and cafés, and even local areas within towns or cities. There is a mix of free and charged-for business models for access to Wi-Fi services. You can find a map of UK Wi-Fi 'hot spots' here.
The most common varieties of Wi-Fi are 802.11b and 802.11g. These both use the 2.4GHz band but have theoretical data rates of up to 11Mbps and 54Mbps respectively (typical real-world speeds tend to be between a quarter and a half of these figures due to environmental effects and data correction). To get the best from 802.11g, all nodes should be at that speed, as 802.11b traffic on the same network may reduce the overall data transfer speed. Similarly, care should be taken if Bluetooth or ZigBee -- which also use the 2.4GHz band -- are deployed in the same area.
Another 54Mbps variant, 802.11a, is also available, but is not compatible with the b and g standards as it uses a different (5GHz) radio band. Although 802.11a is uncommon and has a slightly shorter range than 802.11b/g, the quiet 5GHz band makes it a good choice in areas that are already densely populated with wireless LANs.
The future for Wi-Fi is 802.11n. This will offer a data throughput of at least 100Mbps -- some 10 times faster than 802.11b, and with a much greater range. Certified 802.11n products should start to appear in 2007, although 'pre-N' hardware is already available. This offers most of the promised range and speed advantages, but may not be upgradeable to the official standard when this is ratified.
Wireless WANs
Wireless WANs use the mobile technologies that form the cellular networks. The most widespread of these are '2G' GSM (Global System for Mobile communications) for voice and '2.5G' GPRS (General Packet Radio Services) for 'always on' data services at a theoretical maximum of 171.2Kbps (around 56Kbps in practice). Other 2.5G technologies are HSCSD (High Speed Circuit Switched Data) and EDGE (Enhanced Data rates for GSM Evolution), although neither are as widely available as GPRS. EDGE can deliver between two and three times the data throughput of GPRS, but is not currently deployed by any of the UK's mobile networks.
The 2G/2.5G networks are slowly being eclipsed by 3G, which offers even faster data rates -- currently the maximum is 384Kbps in the UK. Business access to 3G services is offered by the four main UK operators -- O2, Orange, T-Mobile and Vodafone -- via 3G data cards for notebooks. O2, Orange, Vodafone and 3 offer handset-based 3G services, and many of these phones can be used as 3G modems for a notebook via a Bluetooth connection. Note, though, that 3G network coverage is by no means universal throughout the UK, and when 3G coverage is not available data services fall back to a slower GPRS connection.
Future, faster, wireless WAN technologies include HSPDA (High Speed Packet Downlink Access), a 3G enhancement dubbed 'Super 3G' that will deliver around 1.8Mbps initially and up to 14.4Mbps eventually. O2 has recently begun an HSPDA trial in the Isle of Man. Then there's Mobile WiMAX (802.16e), a mobile version (currently still under development) of the fixed WiMAX (802.16a) wireless technology that will serve 'metropolitan area networks' (MANs) and provide 'last-mile' broadband connectivity in remote rural areas. Beyond that, there's 4G, for which a number of technologies are still competing and whose final shape in the UK and Europe (and elsewhere) is still to emerge.
