From the Financial Review www.afr.com
by
John Davidson
Got a spare PC and a wireless networking card lying around? Want to do your community service, thinking globally and networking locally? Then the wireless WAN wants you.
Around Australia, a growing number of communities are taking advantage of low-cost wireless LAN (local area network) technology to build suburb-, town- or, it's hoped, even city-wide networks that give new meaning to the concept of the WAN (wide area network).
Using off-the-shelf 802.11b "wi-fi" wireless LAN technology and a little custom software, community groups are hoping to create huge "mesh" networks which join dozens or hundreds of wireless LANs into one giant network.
Get enough people to sign up, each one donating a little of the bandwidth of their own wireless LANs, and eventually users will be able to share data, play computer games and even video-conference with each other across town, skipping from LAN to LAN without ever using the phone system or the internet.
Or so the story goes.
Getting the critical mass of willing participants has been something of a challenge, says Duane Groth, a 24-year-old self-employed IT contractor who's been attempting to build one of Australia's most ambitious community networks: one that covers the whole of Sydney.
"The biggest problem is just making a start," he says.
"Once an area has a start, people start taking a lot more interest, and they find that it's really useful, so they get their friends involved and it takes off," says Groth, whose mesh is documented at www.nodedb.com.
Mesh networks work by adding a layer of routing and security software on top of a household's wireless network, and then making that network available to all other wireless LANs within range.
Like most other proponents of the networking technology, SydneyWireless, as Groth's project is called, makes that software available free of charge to anyone who wants to install it. It typically comes as an internet downloadable file which, when burnt onto a CD ROM, will make a bootable CD that turns an old PC into a Linux computer, with the mesh software running on top of Linux.
However, some mesh companies, such as LocustWorld in the United Kingdom, sell PCs pre-configured with the software. LocustWorld says it sells the PCs at cost.
Though the routing software is complex, the concept of a mesh network is pretty simple: if enough LANs join the mesh, then a user on one wireless LAN at one end of town should be able to send data to a user at the other end of town, even if the two users' individual wireless LANs aren't within range of each other. To make the journey, data sent from the first user gets routed to the nearest LAN in range, and then onto a LAN within range of that second LAN, and so on, hopping from LAN to LAN until it finds its way to the intended recipient.
Security software means that only the recipient can read the data.
Mesh networks can be surprisingly fast, adding a delay measured in just milliseconds, meaning that some people use them to run videoconferencing applications such as Microsoft NetMeeting, instead of picking up the phone.
But the concept doesn't exactly make for free communications.
Typically, people wanting to join in need to dedicate a spare PC to the routing task, loading it with the Linux operating system as well as a dedicated wi-fi card that's used to contact other networks in range.
And while mesh networks are used in the US to share broadband internet connections across a whole community, that's not usually the case in Australia, says Groth.
Most broadband companies here put a limit on the amount of data each subscriber can send and receive, and charge a premium for any data above that limit. Sharing the internet connection on a mesh would quickly send most users broke, and most people just use them as a local alternative to the internet, useful when they're communicating with other people on the same mesh, says Groth.
Still, there's some way to go before the dream of community-wide mesh is a reality.
One problem with mesh networks is that there are different systems available, and not all are compatible with each other. Although most mesh systems are cobbled together from standard internet routing and security software, there's no industry-wide standard on which components to use, and how to do it. MeshNetworks, a US-based technology supplier, has patented its mesh software, for instance, meaning it's unlikely to make it into other, open-sourced mesh systems.
Another problem is the range of individual LANs, which can be so short that the mesh needs dozens of participants in one small area just to ensure end-to-end connections. Range is highly variable when it comes to radio communications, and while most wi-fi technology advertises a range in the hundreds of metres, users often find they get only a fraction of that, with the signal getting blocked by brick walls, windows or even trees.
"Most users are geographically challenged," notes Groth. "There are buildings, trees, hills, God knows what else getting in the way."
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