The total cost of your project is largely dependent on your project goals and how much work you're willing to do yourself. While you can certainly spend tens of thousands of dollars on outdoor, ISP-class equipment, you may find that you can save money (and get more satisfaction) building similar functionality yourself, with cheaper off-the-shelf hardware.
If you simply want to connect your laptop to someone else's 802.11b network, you'll need only a client card and driver software (at this point, compatible cards cost between $50 and $200). Like most equipment, the price typically goes up with added features, such as an external antenna connector, higher output power, a more sensitive radio, and the usual bells and whistles. Once you select a card, find out what the network settings are for the network you want to connect to, and hop on. If you need more range, a small omni-directional antenna (typically $50-$100) can significantly extend the roaming range of your laptop.
If you want to provide wireless network access to other people, you'll need an access point (AP). This has become something of a loaded term and can refer to anything from a low-end "residential gateway" class box (about $200) to high-end, commercial quality, multi-radio equipment ($1000+). They are typically small, standalone boxes that contain at least one radio and another network connection (like Ethernet or a dialup modem). For the rest of this book, we'll use the term access point to refer to any device capable of providing network access to your wireless clients. As we'll see in Chapter 5, this can even be provided by a conventional PC router equipped with a wireless card.
While a radio and an access point can make a simple short range network, you will more than likely want to extend your coverage beyond what is possible out of the box. The most effective way of extending range is to use external antennas. Antennas come in a huge assortment of packages, from small omnidirectional tabletop antennas to large, mast-mounted parabolic dishes. There isn't one "right" antenna for every application; you'll need to choose the antenna that fits your needs (if you're trying to cover just a single building, you may not even need external antennas). Take a look at Chapter 6 for specific antenna descriptions.
2.1.1 Site SurveyThe most efficient wireless network consists of a single client talking to a single access point a few feet away with absolutely clear line of sight between them and no other noise on the channel being used (either from other networks or from equipment that shares the 2.4GHz spectrum). Of course, with the possible exception of the home wireless LAN, these ideal conditions simply aren't feasible. All of your users will need to "share the airwaves," and more than likely they won't be able to see the access point from where they are located. Fortunately, 802.11b gear is very tolerant of less than optimal conditions at close range. When planning your network, be sure to look out for the following:
• Objects that absorb microwave signals, such as trees, earth, brick, plaster walls, and people
• Objects that reflect or diffuse signals, such as metal, fences, mylar, pipes, screens, and bodies of water
• Sources of 2.4GHz noise, such as microwave ovens, cordless phones, wireless X-10 automation equipment, and other 802.11b networks
The more you can eliminate from the path between your access points and your clients, the happier you'll be. You won't be able to get rid of all of the previous obstacles, but you should be able to minimize their impact by working around them.