WISP Tips Part I
July 02, 2008
Fixd wireless expert, Jack Unger, shares his wisdom on business planning, wireless network design, and management.
Jack Unger, the traveling Johnny Appleseed of broadband wireless and Wi-Fi at Ask-Wi.com, spoke with ISP-Planet's Alex Goldman at ISPCON about common mistakes WISP operators make. He divided his list of WISP mistakes into four categories:
- Business planning
- Wireless network design
- Deployment and installation mistakes
You need to have someone with a business background," Unger said, "although it doesn't have to be you. I didn't hire an accountant when I started my business, and I'm still trying to catch up 15 years later."
Find a niche: When planning the business, remember that the WISP business is a niche business. Unger advised the group to search for unserved customers and not to go head-to-head against the DSL and cable services.
Technology: Learn how wireless works Don't plan the business without understanding the physics.
Throughput: Avoid putting too many customers on each access point. . Plan conservatively. Overestimate the amount of throughput each customer will require. Understand the difference between the actual throughput that you can deliver and the raw data rate that the equipment vendor advertises.
Tiers of service: Unger urged WISPs to offer tiered levels of service. "Offer each user what they need. One user may want to just do e-mail while another will want to do more."
Network monitoring: Don't fail to monitor the network. Track network statistics such as packets dropped and other errors. These statistics can help you predict emerging problems and address them before network failure occurs.
Lightning: Don't fail to use lightning protection. "This costs about $50 per customer. It prevents equipment damage, service interruptions, loss of customers, and loss of reputation," said Unger. "In a worst case scenario, lightning could hit a house or a business computer system, or even harm a person."
Installation: You need to have an efficient install process across your entire installation force to reduce costs and customer service calls.
The law: You need to account for FCC regulations. And you need to know and follow the law. "Some people are running 20 watt amps. That's like driving through every red light in the street. It's makes us all look bad. Please operate legally."
An ISPCON attendee asked, "why is Hyperlink allowed to sell high level amps, at 5 watts and even 25 watts?"
The answer, Unger noted, is on the Hyperlink website. The product page says, "These amplifier products are available only for export, military, licensed amateur radio and OEM component sales and are not offered for general sale within the USA."
Unger said that other vendors (NOT Hyperlink) post such disclaimers but don't observe them.
Wireless network design
Here's the most common WISP mistake: failing to understand how wireless networks behave differently than wired networks. A surprising number of people assume they know how it works, but keep making key errors.
NLOS limits: Even non line of sight equipment (NLOS) has limits. "So-called NLOS equipment does not go as far when the wireless path is obstructed compared to the distance that could be covered if the wireless path was NOT obstructed," Unger said.
Noise reduction knowledge: Unger now offered his favorite piece of advice. "We have to become noise reduction experts." This is a topic he could talk about for days.
"You must understand the concept of signal to noise ratio (SNR), Unger said.
Here's a simple noise reduction tip: "we can simply tilt down our antennas to reduce noise."
Receivers: Understand the concept of receiver overload. "Receivers are not protected from noise. Use enough antenna separation and proper bandpass filtering to prevent overloading and throughput reduction."
Mess networking: Don't fail to thoroughly research mesh networking equipment, if you're considering using it. "Understand the throughput limits of mesh (mess!) networking," Unger said. "Use more than one radio per access point. Make sure you have a separate wireless backhaul."
Routing: Always use routing in your network. "Bridging is not enough to protect and preserve your limited network throughput capabilities."
Test your equipment: Don't forget to test your equipment in house. Some is delivered broken.
Waterproofing: Check your waterproofing and learn how to do it right. "If there's a problem, the equipment will stop working not during a rainstorm but days later when the sun comes out."
Measuring dB: Understand that dB are measured on a logarithmic scale. This means that power declines very rapidly as the signal moves through the air without a wire.
Another Unger pet peeve: "many WISP owners buy a spectrum analyzer but only a small percentage learn how to use it. Learn how to read it. Learn how to use every dial on it. Learn how to capture noise images. Learn how to solve problems."
Link Budget: Learn how to do a link budget and use it to select the correct equipment.
Self-interference: Avoid self-interference. "It's instinctive to blame someone else, instead of ourselves." (For more on this, read, "WISP How to: Detect and Avoid Self-Inflicted Interference."
Antenna height: Avoid installing antennas too low.
Ground: Don't forget to ground the equipment on your network!
An ISPCON attendee asked whether AC and DC current can be grounded at the same point. Unger's answer was, "yes." But of course, you need to check the ground yourself. Don't rely on something someone else installed.
Ping Testing: "Test your wireless links by using large (at least 1000-byte) packets," Unger said. " Small packets can verify connectivity but will not verify that your network can deliver good wireless throughput."
Article adapted from ISP-Planet.