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What Questions to Ask When Choosing a 3.65 GHz Vendor
Now that 3.65 GHz radio gear is available what questions do carriers need to ask to find the right vendor?
I have certainly been a big proponent of the 3.65
GHz space now that radio gear is starting to emerge. I really think this could
be a very useful band for carriers. The band allots a bit more power than
traditional unlicensed band spectrum which offers the potential of some modest
non-line-of-sight capability with good bandwidth.
But like most things the devil is in the details; and since we don't have radios
in this spectrum with a lot of history in the US, how do carriers decide which
vendor is right for them. Well, I won't attempt to give some homogenous answer
because I think the choice will vary depending on the carrier's needs. But there
are some basic questions you can ask to help you decide.
First covering some basics about 3.65 GHz helps. The FCC chose to define the
band to allow a maximum of 1 Watt per MHz for base stations and outdoor CPE
units at the customer site. The indoor portable/mobile unit is limited to 50
milliwatts because this is still technically a shared use band and the FCC
wanted to limit interference from more mobile applications. The intent here it
seems to me is to define a mostly fixed wireless play. This is no judgment on
whether or not Mobile WiMAX or Fixed WiMAX technology would be best as both can
be configured for this spectrum. Also WiMAX technology was blessed for the lower
25 MHz of the band and the top 25 MHz requires a "contention protocol" system
for approval.
So what are the questions? The first for most carriers would probably be price,
but I would argue that should be a question for near the end of your list. Price
is critical, but if gear doesn't meet your customers' needs otherwise cheap
doesn't help.
It appears that each vendor so far has made different choices in how to
implement a solution. The NTIA has certified products from three vendors,
Redline,
Alvarion and
Airspan. The three vendors have
partially chosen different channel sizes. So your first question is what are
these? If you have an application that needs a 10 MHz channel size a 3.5 MHz or
5 MHz or 7 MHz channel pattern may not work. Conversely the vendors were
certified with different amounts of overall bandwidth, the amount of which is
clearly another question you need to ask.
Also too, all three vendors appear
to have only gotten their products certified for the lower 25 MHz of the total
50 MHz available---at least for the time being. When the FCC blessed WiMAX radio
systems it did so in the lower 25 MHz. I believe Airspan has said that its
solution will work in the upper 25 MHz portion (contention protocol section) as
well, but so far as I can determine it has not been certified by the NTIA in
that portion as of yet.
The amount of power that each vendor has been approved for appears to vary as
well depending on their channel size, technology implementation and other
criteria. This will affect NLOS performance. One vendor told me that in a
heavily forested and hilly area like Asheville, NC where I live NLOS performance
might average .8 to .9 mile, but that a more urban and less forested market like
Atlanta, GA might achieve 1.2 to 1.3 miles of NLOS performance on average. Like
with most things wireless there are tradeoffs so ask your vendor what their
approved power allotments are.
Another thing to consider is the future so ask a lot of questions about
potential interoperability (and vendor plans to achieve it) across the three
vendor platforms as well as other technologies and spectrum ranges. There is, it
seems to me an opportunity in the next couple of years for 3.65 GHz operators to
potentially interoperate and roam across each other's networks. Now having said
that mobile devices have a power limitation that could be a minimal opportunity,
but it is more potential than non-licensed players have had before.
Are these the only questions to ask? Absolutely not. These are just a few of the
first basic ones to ask. Each vendor's value proposition goes far beyond these
basic elements. Obviously the real test is in the field. And trying out a
solution from each, if that is something your carrier can afford to do is
probably the best way to see how they actually perform. Have fun!
Tim Sanders
The Final Mile
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