How to be an ISP:

Build your own hot spot

By Dong Ngo

If you go to the CBS Interactive building at 235 Second Street in San Francisco and turn on your laptop, you will find an access point called “CBS_Interactive_Public” that offers free wireless Internet access. That’s a typical example of a hot spot.

However, it doesn’t take a tech news company or even an organization to create a hot spot. You can do it by yourself. It’s easy and fun, and–if you want–you may even make money from it.

In the last few years, the amount of devices that have built-in Wi-Fi has increased tremendously. In fact, despite the economic downturn, the sales of Wi-Fi chipsets have been constantly rising.

However, the Wi-Fi feature of these devices is useless on the go, unless there’s a hot spot.

What’s a hot spot?

In general, a hot spot provides users’ unfettered access to the Internet via one or more wireless access points.

The cost for using a public or private hot spot can vary. For example, CBS Interactive’s headquarters, or many schools or community centers in big cities like San Francisco or New York, offer this service for free. Companies, such as T-Mobile, hotels, or other organizations may charge membership fees.

We’ll tell you how to set up your own hot spot, from determining your coverage area to installing and controlling access to your network. However, before we begin, make sure your ISP lets you share your Internet connection. Some companies don’t care, while it may be a violation of your Terms of Service with others.

Who you want to connect

Where you want them to connect

What your ISP’s connection-sharing policy is for your service

Which network resources on your network require protection from hot-spot users

Follow these five steps

Step 1

Determine hot-spot coverage: The goal of a hot spot is to cover a public area with an 802.11 signal. Most of the decisions about how and where to mount your access point and what antenna to use will depend on your desired coverage area.

For small areas close to the physical location of your access point, a standard device such as one offered by your service provider or any wireless routers you can get off-the-shelf would do the job. Among those reviewed by CNET, Draft N (or 802.11n or Wireless-N) routers are faster and offer larger coverage than 802.11g routers.

However, if you want to provide coverage to a municipal park a mile away, you will need to attach a more sensitive antenna and establish a line-of-site connection between your access point and the hot-spot location.

	Wireless standard				Characteristics
	802.11				Operates at 2.4GHz; the lowest common denominator of the IEEE wireless LAN standards; provides bandwidth of only 1Mbps; equipment based on this older standard may be hard to find.
	802.11b				Operates at 2.4GHz; backward compatible with the older 802.11 standard; delivers bandwidth of up to 11Mbps. This once-popular standard is becoming obsolete and routers/access points based on this standard are hard to find.
	802.11g				Operates at 2.4GHz; delivers bandwidth of up to 54Mbps; backward compatible with 802.11b; currently has the largest user base, especially in mobile handheld applications.
	802.11n				Also called Draft N; operates at 2.4GHz and 5GHz ; currently a draft specification awaiting ratification by the IEEE; delivers bandwidth of up to 300Mbps; backward compatible with 802.11g and b (when operated at 2.4Ghz); we expect this standard to co-exist with 802.11g as the standards of choice.
	Bluetooth				Operates at 2.4GHz; is a short-range, low-bandwidth solution designed to connect peripheral devices without the use of cables; is not compatible with any of the above standards; is not well suited for hot-spot deployment.

Step 2

Click to enlarge Yagi antenna.

Choose an antenna type: If you use a Wireless-N router and have a relatively small area to cover, say a restaurant or a cafe, the built-in antenna of the router should suffice. For larger area, you will need a high-gain antenna capable of bridging the gap. High-gain antennas concentrate radiation in a certain direction, in much the same way that flashlights focus beams of light. A low-gain, omnidirectional antenna spreads the signal in a 360-degree circular pattern, whereas a high-gain antenna focuses the signal in a particular direction, reducing the coverage from 360 degrees to 180 degrees or less. However, because a high-gain antenna delivers a more-concentrated radiation pattern, it’s capable of spanning a greater distance. For example, a 24dB-gain antenna may reduce your coverage to a 10-degree swath of space but will dramatically increase the sensitivity and range of your access point in one direction.

Step 3

click to enlarge Assorted pigtails.

Connect the antenna: Once you’ve determined the appropriate antenna based on your desired coverage area, you’ll need to attach it to your access point or wireless router. (A wireless router is a regular router with a built-in access point). While most antennas feature N or SMA connectors, access points can vary. Check the access point’s documentation or the company’s Web site for information on connector types. The NoCat Project also provides a list of the more common connector types. To attach an external antenna to your access point, you generally need a pigtail, a short length of cable with connectors on each end. However, because a pigtail can introduce a significant amount of signal loss, make sure you keep it as short as possible. In fact, we recommend you mount your access point on the roof next to your antenna. For tips on how to weatherproof your access point, see Step 4. pigtails from several Internet sources. Some Web sites sell FCC-certified setups, which means the antenna and the access point have been tested and certified to work together. We recommend purchasing an FCC-certified setup, especially for large-scale installations.

Step 4

Mount the antenna: If your entire setup sits inside, mounting the antenna should prove easy. However, if your rig sits outside, you will need to put your access point into a weatherproof case. Just how much weatherproofing you need to make the enclosure depends on the local climate. There are both commercial and home-brew options available, depending on your level of crafting skills, it can range from something as simple as putting the device in a close box or elaborate.

Providing power to an outdoor access point can be difficult. Some enterprise-level access points such as the AirPointPro deliver power over the unused wires in an Ethernet cable. To provide full power over Ethernet, you must use a power injector or a switch. You can also build a simple version for short runs with a few dollars’ worth of parts.

Step 5

Lock down your network: Generally, if your hot spot is open to the public, you’d want to separate it from your home or office network while allowing it to share your access to the Internet.

There are many ways to do this, but the easiest is to use a router that supports a Guest Zone (or Guest Networking), such as the D-Link DIR-825 or the Apple Airport Extreme Base Station. Many other routers also have this feature; just make sure you look for on its feature list.

Guest Zone lets you create a separate wireless network that permits access to the Internet, but not your local network resources, such as your computer or printer. With a router that supports Guest Zone, you can have two wireless networks at the same time, one for your own use and the other to serve as a public hot spot.

Once you have lit up your hot spot, you can let people know about it by listing it in a public hot-spot database. You can offer your hot spot as a paid service in conjunction with a billing partner such as HotSpotSystem. You can also restrict your hotspot with wireless encryption that you will need to give out to users.

If you are more inclined to high-tech philanthropy and plan to offer the hot spot as a free community service, you can list it in a hot-spot database.

Creating a hot spot is easy. In the simplest scenario, it requires nothing more than turning on your wireless router or plugging in an access point into a regular router. This guide, however, helps you create one that minimizes the security risks. If your hot spot is connected to your home network, consider placing a firewall between them.

Last, but not least, if you add antennae to your system, make sure that you are operating in accordance with FCC guidelines. Using an amplifier or the wrong antenna can wreak havoc with other networks and hot spots in the area.