Building Wireless Community Networks, Second Edition

The WISP Approach

Visions of license-free, monopoly-shattering, high-bandwidth networks are certainly dancing through the heads of some business-minded individuals these days. On the surface, it looks like sound reasoning: if people are conditioned into believing that 6Mb DSL costs $250 per month to provide, then they’ll certainly be willing to pay at least that much for an 11Mb wireless connection that costs pennies to operate, particularly if it’s cleverly packaged as an upgrade to a brand name they already know. The temptation of high profits and low operating costs seems to have once again allowed marketing to give way to good sense. Thus, the "Wireless DSL” phenomenon was born. (Who needs an actual technology when you can market an acronym, anyway?)

In practice, many WISPs^[2] are finding out that it’s not as simple as throwing some antennas up and raking in the cash. To start with, true DSL provides a full-duplex, switched line. Most DSL lines are asymmetric, meaning that they allow for a higher download speed at the expense of slower upload speed. This difference is hardly noticeable when most of the network traffic is incoming (i.e., when users are browsing the web), but it is present. Even with the low-speed upload limitation, a full-duplex line can still upload and download data simultaneously. Would-be wireless providers that build on consumer-grade wireless technology are limited to half-duplex, shared bandwidth connections. That means that to actually provide the same ...