June/July 2003

The 802.11b wi-fi standard is being formally joined by the much faster 802.11g

Faster data transfer rates on wireless local area networks could be on the way. The Institute of Electrical and Electronic Engineers has at last ratified the 802.11g amendment to its 802.11 series of wireless network specifications, which allow any products conforming to the standards to work together on the same wireless network. The IEEE is an international organisation that develops standards for electronic and electrical technologies.

In the UK, the majority of WLAN networks currently operate on the IEEE's 802.11b standard. That includes the kind of private wireless networks you get in warehouses and transport depots, as well as the new generation of public-access Wi-Fi "wireless hotspots" where you can log on to the Internet from portable computer devices.

The 802.11g standard uses the same 2.4GHz band as the widely deployed 802.11b, but employs a different data coding method which allows more data to be squeezed into the same wavelength. Raw data transfer rates are increased from the 11 megabits per second achievable on 802.11b to 54 Mbps. The downside is slightly shorter range, higher susceptibility to interference and higher power consumption because of more intensive signal processing. There is backwards compatibility, so any 802.11g handheld computers should work on an 802.11b network.

"IEEE 802.11g gives WLAN suppliers and users added flexibility in choosing systems that best fit their needs," says Stuart J Kerry, chairman of the IEEE's 802.11 working group. "Given the millions of 802.11b-based WLANs in place worldwide, the market demand for the extension to 54 Mbps has been quite strong. The higher speed extends the use of this widely deployed WLAN technology into a growing variety of business and public networking applications."

Some handheld computer specialists, including LXE, say that 11Mbps is perfectly adequate for most warehouse date capture applications, but concede that developments such as Windows CE-based operating systems and voice-activated applications could drive up demand for radios with higher bandwidth capacity.

In the US, some manufacturers predict a limited life for 802.11g and a gradual migration to the older 802.11a standard. This operates on the 5GHz band, but while technical implementation problems are being resolved, the range is less than on 2.4GHz. Dual-band handsets are being developed, although whether these will be a+b or a+g, or even all three, remains to be seen. They will certainly cost more ­ not least because, as LXE points out, the majority of today's data capture units use 16-bit interfaces, not the 32-bit interface required by 802.11a.

It may be a different story in Europe. Unlike the US, operating on the 5GHz frequency in Europe generally requires a licence, not least because the band is used by military organisations, including NATO.

The European Telecommunications Standards Institute is working with the IEEE and the Japanese MMAC to create global standards for 5GHz systems, but 802.11a does not fulfil its requirements, especially for outdoor use. However, ETSI is finalising its 5Ghz Hiperlan 2 standard, which is complementary to 802.11a but includes extra protocols such as Dynamic Frequency Selection and Transmit Power Controls.

The range limit and extra cost of 5GHz systems may be prohibitive for the requirements of many warehouse WLANs, but could prove attractive for delivery operations. Handsets that have an 802.11a card may be able to link into the wireless hotspots now being rolled out. It could provide coverage in areas where GSM or GPRS link is lost, for example.