Best of the ISP-Lists

My Jurassic Antenna Will Last Forever

Members of the ISP-Wireless list debate the expected life of fixed wireless broadband equipment. This is a business and financial issue as well as a technical issue—how long before you need to buy a new antenna?

[July 24, 2001]

On the ISP-Wireless list in June, PB inquired,

"One of my colleagues in the financial division of our company asked me about the expected lifespan of wireless equipment. I told him I assumed 3-5 years. Any thoughts?"

A number of respondents suggested limiting it to three years:

[TL warned] "If you are talking about capital expenditures, I would not go over three years."

[AG agreed] "Our business plan assumes that the equipment will last for three years, and we plan our costs so that the equipment has been paid for by the customer after 9 to 12 months."

Others advised even lower limits:

[LS suggested] "It's all still too new to have any accurate figures. Based on my experience with outdoor radios, I think you are going to find that two years is about the point where service becomes a serious issue."

[JD agreed] "If you think about it, the technology changes so fast that two years would make most equipment a living dinosaur. We are just now getting our first major influx of new customers, and we are already looking to replace our current system."

Others agreed that it's the advancement of technology, not equipment failure, that's the real issue:

[JK noted] "I have had my equipment running for over four years with no failure. The Mean Time Between Failures (MTBF) is stated as 180,000 hours (over 20 years) according to the manufacturer. The technology will become obsolete before the radios ever fail in large numbers."

[LY advised] "The gear may last longer, but you should really consider a two year plan. If you cannot pay off the equipment and build enough cash for the future upgrade within that two-year period, you need to revise your plan so that you are on the top of the game when the new stuff is on the market."

[JL added] "MTBF is measured at a 25°C ambient temperature. The major component of lifetime calculations is temperature; the hotter it runs, the quicker it dies.

MTBF calculations also do not consider other environmental conditions such as lightning, static, gunshots, mechanical damage, power glitches, corrosion, etc. Your actual lifetime will be seriously affected by the operating environment. If you're really into reliability predictions, see the various links at: www.i-mtbf.com/links.html.

The real question isn't about MTBF, but about how long it'll take before radios become obsolete. My guess is about four years: obsolescence is the price of progress."

—End