Look, no wires

Look, no wiresDuring the past year, three viable contenders have emerged in the wireless networking arena. While they all use the same license-free portion of the radio spectrum, they have differing target markets. Work towards a wireless version of traditional twisted-pair cable-based local area network (LAN), or Ethernet, has been ongoing for some seven years. Last year a specification for wireless LAN was finally unveiled – the IEEE802.11 standard. Earlier this year a consortium of companies announced a home networking initiative. The HomeRF working group aims to link devices in the home and small office. Just last month, another consortium this time headed by Ericsson, but including Intel and Microsoft, announced Bluetooth, a low cost, short range system for linking laptops to mobile phones and the like. All three systems have their relative merits and will work better in certain environments and applications. But at the moment it is unclear which will gain the ascendancy, or whether two or more can co-exist in the market-place.   Wireless LAN Bluetooth HomeRF bit rate up to 11Mbit/s 1Mbit/s 1-2Mbit/s no. channels 10 – 20 8 per net 127 range 50 – 200m 10m 50m power 100mW 1mW 100mW chip cost < $50 < $10 $25-ish aimed at office mobile user home All are using the unlicensed RF spectrum at 2.4GHz, called the industrial, scientific and medical (ISM) band. Like other competing technologies there is a series of trade-offs and compromises that go with each. Wireless LAN – IEEE802.11 Ratified as a standard last year, wirelessLAN promises better flexibility in office environments. New users can be logged into a system more quickly, and users with laptops can work in any part of a building and move around without logging on and off. Wireless LAN is starting to move into general use. “What’s been happening so far is vertically oriented use of wireless, for example medical markets,” said Paul Sherry, European marketing director for NetWave. “There’s not been a broad acceptance because there’s been no standard.” The IEEE802.11 standard changes this. “Companies are now bringing products to market. We’re seeing a movement towards the broader market-place,” Sherry said. This is spilling over into other applications such as mobile phones that use voice over Internet protocol to give free calls when the user is within the range of the wireless LAN system. This is remarkably similar to dual DECT/GSM phones. Sherry expects the large networking companies such as 3Com and Cisco to get involved with wireless LAN in a big way, especially when systems move to 10Mbit/s. One company making a push to this bit rate is Harris, which supports the wireless LAN protocol through its Prism chipset. The chipset includes the baseband processor, software media access controller and transceiver chips. Data rates are 1 or 2Mbit/s. Harris recently announced a baseband chip running at 11Mbit/s, with the transceiver chips to follow. “11Mbit/s in the ISM band is going to be a sweet spot over the next few years,” said Ron Van Dell, v-p of communications at Harris. This sort of data rate will enable data streams such as DVD to be transferred, removing the need for wires between computers, stereos and TVs. l A group calling itself the personal area network (PAN) group has requested that the IEEE802.11 committee forms a working group for a cheaper version of wireless LAN. The 1Mbit/s link would work over a 10m range. HomeRF Announced in March, the HomeRF working group comprises an impressive list of companies. Compaq, Ericsson, Hewlett Packard, IBM, Intel, Microsoft, Motorola and several others are involved. Incidentally, most of these are also in the Bluetooth group. While wireless LAN is aimed at the office, large or small, and Bluetooth is for linking laptops to mobiles, HomeRF aims to completely remove the need for wiring in the home or small office. “There’s more computing power and equipment in the home today, and a lot of cabling comes with it,” said Henk Koopmans at Symbionics, which helped develop the protocol for HomeRF. HomeRF’s protocol, the shared wireless access protocol (SWAP), is based on a mixture of wireless LAN and DECT. Wireless LAN provides the carrier sense multiple access with collision avoidance data transfer method for general packet data. DECT, using time division multiple access, allows voice to be placed on top. Because it is aimed at the home, the system will integrate heating and lighting controls. Home owners could remotely control everything in the house via a telephone keypad. Bluetooth This low cost, low power, short range link is not just aimed at home or office networks but also at people on the move. A document or image on a laptop computer could be sent over the GSM network without physically linking the PC and mobile phone. In fact the phone need not be taken out of a briefcase or glove compartment. “I think the Bluetooth announcement is very important because it spreads awareness and provides a neat, small interface,” said NetWave’s Paul Sherry. The entire interface fits into a few square mm of silicon – the size of a tooth we suppose – and will cost less than $10. Cellphone, laptop and digital camera manufacturers are expected to start fitting the devices from next year. “We don’t see it as a wireless networking technology because of its low power output and small area coverage,” said Harris’ Van Dell. “It’s a more practical alternative to infra-red.” This pushes Bluetooth down to number three in Harris’ list of priorities. Wireless LAN is number one, with HomeRF second. Because all the systems thus far announced use the same frequency, Van Dell is concerned about clutter in the spectrum, leading to interference. This is particularly true of Bluetooth, he said, because it is always ‘on’. “We don’t now what the effect will be yet. There’s not much in that space yet except a few microwave ovens.” Whichever of these three technologies gains the upper hand, the consumer wins in the end. It seem the age of the wireless network is here. As Koopmans at Symbionics says:”This is the right time for complex RF technology to be commoditised.”


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