iWeek Opinion: Common pitfalls of deploying a public wireless network

18 August 2008

Jack Unger, President, ASK-Wi.Com, USA

Successful wireless Internet service providers (WISPs) are independent and strong-minded entrepreneurs. Even so, they face a range of hurdles and potential mistakes, many of which can be avoided. Broadly speaking, these mistakes can be divided into five categories namely business planning, wireless network design, deployment, installation and support mistakes.

One of the most important elements in a successful WISP business is the skills of someone who has a business background. Although technical expertise is critically important, you need to have someone on board who can help you manage finances, regulatory issues and customer service. For example, many WISPs imagine they can get the business going and worry about hiring an accountant later. By the time “later” rolls around, the business could be so far behind that recovery is difficult.

When planning the business, one needs to remember that WISPs are niche players. Instead of going head-to-head with the fixed-line and mobile networks, rather seek out under-serviced customers and markets. WISPs that offer tiered service levels enable a range of customer needs to be met, from light browsing and email through to heavier downloading of media files.

On the technology front, a common mistake that many WISPs make is to plan the business without learning about the physics of how wireless works. Failing to understand how wireless networks behave differently from wired networks is perhaps the most common mistake of all.

For example, many WISPs have to learn through bitter experience not to put too many customers on one access point and not to underestimate the amount of throughput each customer will need.

The WISP operator also needs to be a noise reduction expert, and understand the concept of signal to noise ratio (SNR). One simple technique is to down tilt your antennas to reduce noise.

I always urge WISPs to use routing in their networks because bridging does not offer enough network control to preserve quality service over wireless networks with limited throughput. In addition, it’s important to remember that non-line of sight equipment (NLOS) has significant distance limitation and does not cover as much distance as expected when the wireless path is obstructed.

WISPs should also invest in lightning protection to prevent equipment damage, service interruptions, and loss of customers. The cost of lightning protection is small compared to the risks lightning poses.

Once the network is in place, you should constantly monitor network statistics such as the percentage of wireless packets dropped because this will allow you to predict emerging problems before the network fails.

A spectrum analyser is an invaluable tool, provided one learns how to use it properly to solve problems. Understanding the concept of receiver overload will also be beneficial. Receivers are not protected from noise, which means that one must use enough channel separation and proper bandpass filtering to prevent overloading and the consequent throughput reduction.

Ping-testing with large packets is important and you should put your wireless links to the test with packets of 1000 bytes or more to ensure that your network can deliver good wireless throughput.

The smart WISP operators try to learn from the mistakes that more experienced WISP operators have already made rather than by re-inventing the wheel. There’s no reason to repeat the mistakes of the past.