Few things are quite as nice as opening your laptop at a coffee shop, connecting wirelessly to a network, and enjoying a cup of coffee. A publicly available wireless network is called a hotspot.
Hotspots are popping up at bookstores, airplane terminals, hotels, and just about anywhere you might think to try to get some mail or do some work on your laptop. Many hotspots are free (so called free-spots) by intent and anyone is welcome to use them. Many more hotspots are free because people don’t turn their wireless security on.
No password and no encryption equals “free,” and for some it is great sport to ride around “hotspotting” or “wardriving” in their cars detecting available hotspots to list on their Web sites. For a primer on warchalking, a related activity, see Warchalking-Introduction.
Keep in mind that jumping on a wireless network uninvited is a form of hacking and an intrusion, so tread lightly. In many instances it makes good business sense to set up a hotspot, and indeed for some companies setting up hotspots is a business in itself.
If you own a motel and want to provide wireless networking to your guests, a hotspot is just the ticket. It can be a service that you charge for, which, if you have enough customers, more than makes up for the low costs involved in setting up a hotspot.
Some companies will sell you a canned solution, a so-called “hotspot in a box.” Other ISPs offer hotspot service as an option on your business account. Without too much effort it’s straightforward to build your own hotspot as long as you know about a few of the hidden gotchas.
Setup a hotspot is very similar to connecting a wireless access point to any DSL or cable broadband connection.
The major difference is that since your customers may generate significant network traffic on aggregate, most ISPs will require that you buy a business-class connection and establish a business account.
Here are some of the steps you need to take to implement a hotspot in your business:
- Perform a site survey. Estimate the physical size of your desired hotspot and determine if your equipment has an adequate coverage area.
Most access points offer coverage of about 300 feet in all directions. Walls can lead to significant drop off, and you may require additional access points and/or repeaters.
- Determine the number of users that will connect on average and at the maximum level. If you figure that each user will require a throughput minimum of 100 Kbps to do e-mail as Intel suggests in its hotspot deployment guide, then more than five concurrent users requires at least a DSL line.
You should also figure that each router can accommodate approximately 25 users. For more demanding throughput of larger file sizes (such as music files) you may find that your five users are using 1.0 Mbps and you will need a cable connection.
In your calculation, keep in mind that not all connected users are generating traffic all the time, and make your estimates accordingly.
- Test the equipment you are using for range, address provisioning features (such as DHCP, DNS, and gateway assignments), and for conflicts with other devices in the wireless range.
To test your wireless coverage you can use a notebook computer, an RF analyzer, or an AP with a test standard feature. When you find a conflict, record the channel used, the MAC address, and the strength of their signal at several key locations.
When you purchase your access point or router, you should get a guarantee from the seller. If your device conflicts with other devices, as is often the case for 2.4 GHz devices, you will need to exchange the item for a different device.
You can get interference from microwave ovens, extended-range cell phones, wireless video monitors, metal walls, and most frustratingly from your neighbors using your same channel. Neighbors can be a problem if your business is in a dense location, less than 300 feet from other businesses.
You’ll need to test for conflicts, and be aware that metal walls do not show up in a site survey using an analysis tool. Perform your tests at different times of the day so that you locate intermittent but regular interference.
- Draw your site and map out the range your access points will have. You should have enough cell size to have good coverage, but not extend out of your desired range.
If necessary, add more access points so that they overlap and lower the power of your access points to get better coverage and serve more users. Your map should also indicate how many users will be in each zone so that you can design your overlap to accommodate the required connections.
- Contact ISPs to get pricing and requirements and determine whether you are going to use a consultant or management service to help you with your hotspot.
A consultant can be useful in setting up complex hotspots, measuring the quality of the connection, and in particular setting up security and billing software associated with a site.
In previous tutorial, you’ve been advised not to advertise your SSID. However, when you want the public to use your access point, it is a good idea for the network to advertise itself by broadcasting its SSID.
It isn’t absolutely necessary for a hotspot to broadcast, but it does allow someone in wireless range to connect without having to ask your staff for the SSID. If you don’t advertise, your users will need to be told your SSID, which has some value in maintaining security.
It’s also a good idea to carefully manage the physical extent of your hotspot’s broadcast to limit access to people who are not frequenting your establishment.
Selecting a Protocol
Any hotspot provider should assume that its customers are going to connect to its wireless LAN (WLAN) using different protocols and cards from different manufacturers. The greatest number of people will probably use the 802.11b protocol to connect. Smaller numbers of people will use 802.11a and 802.11g.
The best you can do is to install an access point that offers tri-band support a/b/g, or install more than one access point to cover the different protocols in use. Look for the following features in your access point/router because they are most likely to be useful to you:
- The ability to extend the range of your WLAN using repeaters and bridges.
- Management software that shows you who is connected, what the throughput was, and other features.
- Reliability and ease of use.
The organization that certifies compliance of 802.11 devices is the Wi-Fi Alliance. It’s a good idea to purchase equipment that carries the Wi-Fi Certified mark. That mark indicates that the access point or router has passed the Wi-Fi Alliance test suite.
You can also post their network logo when you register your site with their directory found at WifiZone.org. Both logos are shown in Figure below.
This gatekeeper device has smart filters, performs user authentication, and has management, logging, and accounting features. Two companies offering this type of device are BlueSocket and Nomadix.
Forget about features such as extended versions of protocols like ULTRA-802.11g or SUPER- 802.11g because few if any of your customers are likely to benefit from the additional capabilities. The best hardware devices are the devices that are as broadly interoperable as possible.
The fewer problems people have connecting to your hotspot, the less time your business is going to lose servicing your customers’ computer problems and the more time you will spend on the business that your hotspot is meant to support. Whenever you have a choice, it’s a good idea to sacrifice speed for reliability.
Because most people either have 802.11b connections or have devices that are in theory backward-compatible with 802.11b, if you must choose a single protocol to get a really reliable unit you should choose an 802.11b access point.
The Acceptable Usage Problem
Not all ISPs encourage or want hotspots on their network. To some it’s a security issue, but for most ISPs the issue is one of throughput: they don’t want their network’s bandwidth saturated by excessive traffic. Check your service contract and you will find a clause in almost all of them that allows service only under “acceptable use.”
The term acceptable use means that your ISP can pull anyone off its network that it deems to be doing something that it doesn’t like. A spammer operating over a combination cable TV/broadband connection is going to get pulled (one hopes), as will any home that is serving up gigabytes per hour of music or porn on a peer-to-peer service.
What most ISPs don’t tell their customers is that there is a threshold level of throughput that triggers the acceptable usage clause. Go beyond that level and you are going to get a letter warning you that you have exceeded your throughput quota.
Service termination follows shortly thereafter. So if you are going to set up a hotspot that many people are going to use, you really have no choice but to call your ISP and tell them what you want to do. You’ll probably do this before you know what traffic your hotspot generates, but this is the time to shop around for a deal.
All ISPs are in business, and their business is selling bandwidth. With a business account and your ISP’s rules on what you need to do to provide secure wireless access to the public, you will not run into this problem.
Your only problem will be paying the bill, and many providers do what the phone company does—charge businesses a premium. So it pays to shop around. Indeed, many ISPs do not allow e-mail to be sent over their network from a mail client when the person connecting to the network does not have an authorized account.
Because most spam is sent using SMTP clients, and this mechanism could be launched to initiate a DOS (Denial of Service) attack through bandwidth saturation, this restriction makes some sense. It would not be possible to stop a user from sending mail from a browser client, but it is much less likely that bulk mail would be sent that way.