On nearly a daily basis, we’re seeing large municipalities, such as Atlanta, Philadelphia and San Francisco, announcing their deployments of city-wide public Wi-Fi networks. These networks cover hundreds of square miles each. It’s also common to see many of the smaller cities, such as my home town, Dayton, Ohio, moving forward with public Wi-Fi service. It appears that soon we’ll have Wi-Fi just about everywhere!

The effectiveness of these city-wide Wi-Fi networks, however, is still yet to be seen. My experiences tell me that metropolitan-area Wi-Fi service will be pitted with poor coverage and unacceptable performance. I don’t want to sound too negative about the proliferation of Wi-Fi - I strongly feel that there are ample benefits, especially for travelers. But, there is certainly lots of room for errors in the design and configuration of a Wi-Fi network the size of a city.

I’ve tested wireless LAN equipment in metro areas, and it’s not easy to provide widespread mobile access. Large structures, such as high rise buildings, often get in the way. In addition, Wi-Fi standards were not really intended for large areas. WiMax, which is slowly becoming available, is likely a better fit for covering metropolitan areas.

System integrators have had problems covering medium-sized venues, such as hotels and airports, with Wi-Fi service. I travel a lot and take advantage of public Wi-Fi access whenever possible. For example, recently I was residing in Philadelphia at the Four Seasons Hotel (the conference organizers were being nice to me) and moderating round table discussions on mobile computing topics. My room there was top-notch and the staff service was excellent, but the Wi-Fi coverage wasn’t too good from my room. Later that same week, I was in Houston staying at a Hyatt, and again Wi-Fi coverage in my room was poor. The commonality among these two hotels is they’re large, and they charge $10 per day for Wi-Fi access.

A while back, I completed a nine-day, 2,500 mile road trip by car throughout much of the south eastern U.S. while working for one of my clients. This project had a tighter budget, so I stayed exclusively at Holiday Inn Express hotels. They’re relatively small and fairly nice for the money. And, they provide free public Wi-Fi service with excellent coverage, at least in the eight separate hotels where I stayed. I guess the old saying that “you get what you pay for” doesn’t apply to public Wi-Fi!

While on these trips (for fun), I generally measure the Wi-Fi coverage throughout as much of the hotel as possible. I’m finding that usually the signal strength in hotel lobbies is excellent and the sleeping rooms (at least the ones I’ve stayed in) have good or poor signal strength. In other areas, such as hallways and elevators, Wi-Fi coverage is generally non-existent. Synchronizing email and browsing the web may be good if you’re lucky, but be ready for dropped calls when using voice-over-Wi-Fi phones when roaming throughout the hotel.

I mention these experiences, which are common to my travels to other places, mainly as the basis to underscore my points about public Wi-Fi service. It’s very difficult to cover the large areas, especially in and around big buildings, such as hotels and airports. In addition, the Wi-Fi service currently available is not consistent in all places. And, how will system integrators manage the deployment of Wi-Fi service effectively in city-wide areas when it’s not being done well for even the medium-sized establishments now? This question scares me a bit.

If you’re a mobile user or an IT manager outfitting users to take advantage of public Wi-Fi, then you definitely want to do the obvious things like securing the mobile devices with end-to-end encryption, such as VPNs. But, don’t expect too much in terms of performance. Before going out and purchasing a truck load of WLAN phones and subscribing to voice-over-Internet services, consider where you’ll be using the public Wi-Fi services and whether coverage patterns will accommodate your needs. If you’ll be using corporate applications that require continuous connections with the server, then think about deploying data replication and wireless middleware solutions to take over if the connection is lost. 

If you’re deploying public wireless LANs, then choose proven equipment and designs. Be certain to review applicable testimonials and even perform testing at live, relevant public Wi-Fi sites that include the equipment that you’re planning to deploy. If relevant sites are not available, build prototypes and conduct pilot tests in a limited area within your environment before installing the entire network. This is especially true with the larger hotspots. Again, I’ve seen too many medium and large Wi-Fi hotspots having lots of coverage holes and unacceptable signal strength.

Pay close attention to the radio frequency (RF) aspects of the system. Always complete thorough RF site surveys at installation sites to determine optimum antenna type and placement. Consider the use of amplifiers too, but don’t forget to apply for licensing with the applicable regulatory agency, such as the Federal Communications Commission (FCC) in the U.S.

The implementation of Wi-Fi service in a coffee shop is one thing, but city-wide deployment is definitely another. In a Starbucks, you can probably get by with a single access point installed just about anywhere within the store. With a city-wide deployment, there are many access points and lots of obstacles that can get in the way. A problem is that environments change in a way that impacts Wi-Fi coverage. For example, tree leaves come and go throughout the year, which offers a significant change in radio wave attenuation and corresponding signal strength that users encounter.

So, don’t hurry the deployments of these larger networks. Instead, fully understand the technical risks, and plan accordingly. Because there are very few of the bigger public Wi-Fi installations, carefully design the system and perform testing to iron out the wrinkles before building a large body of subscribers. This is undeniably a case where you have to learn how to walk before you can run! 

Jim Geier is an independent consultant and founder of Wireless-Nets, Ltd (www.wireless-nets.com), a consulting firm assisting municipalities, enterprises, hospitals, airports, and equipment providers with the development and deployment of wireless networks.