Better wireless networking radios emerging
March 7th, 2006One of the limitations of community wireless has been that the Wi-Fi (802.11) devices which tend to comprise them are far from ideal. On one hand, they are very inexpensive and ubiquitous in the market, and there is a great deal of support and maturity in the software applications that drive them. On the other hand, 802.11 was never intended to be a solution for wide-area, outdoor mesh networks: it was designed to work well in offices, public spaces, airports, conference rooms, etc.; in other words, 802.11 is for hotspots. “Meshes” of access points are not supported out of the box, for instance. On top of that, the part of the radio spectrum that these devices operate in - 2.4 GHz and 5.x GHz - have physical properties that make it hard to deploy networks in dense urban environments, as well as any community with a lot of tree coverage: the signal just does not penetrate physical obstructions very well.
Projects like CUWiNware have tried to address these shortcomings in the 802.11 software and hardware for outdoor mesh networks by using the particular characteristics of the medium as decision-making input for desired behavior, like mesh routing. This has worked very well - the WCN project has deployed over 60 rooftop nodes to date in two Chicago neighborhoods using this technology - but software can’t by itself fix the problem of poor radio wave propagation. What we need is better access to higher-quality spectrum, lower frequencies that penetrate better than 2.4, especially. This is the issue that bills like the ones introduce recently in the US Senate and written by the New America Foundation have tried to address: opening up sharing in bands like the TV broadcast spectrum, radio waves’ equivalent to beachfront property.
What’s also required in addition to better spectrum policy are smarter, more efficient, and more flexible radios. Despite the Apple.com-style ripoff home page, Ubiquiti Networks deserve a look because their latest product is a step in that direction. It is an innovative radio that uses the 802.11 protocol but operates in a different frequency: the 900 MHz band which is unlicensed like 2.4 GHz and 5.x GHz, but has been primarily been used by expensive proprietary devices with a smaller market penetration than Wi-Fi. What this means is that computers and access points can pop in this new radio and it will work without modification to existing software - because it’s 802.11 - and they will immediately get all the benefits of operating at a lower frequency, namely, better signal coverage and penetration. Long links that have to cut through trees will not suffer as much loss, and dense urban meshes will not have to engineer costly installations to get around building obstructions.
It remains to be seen just how seamless the Ubiquiti SuperRange9 works with existing devices. And it won’t solve all the mesh networking problems - the 802.11 networking internals still use what’s called a contention process for talking to other 802.11 devices, which can lead to monopolization of the channel in certain environments; a time-divided, or slotted, process would be more efficient and give better performance. And network operators would still need to determine how to backhaul their networks and what kind of client access to provide, because existing laptops and PDAs can only talk in the traditional 802.11 bands, not 900 MHz. But the entry of a device like the SuperRange9 hopefully marks the beginning of more innovative radios that give community networkers greater flexibility and ultimately less headaches and cost.