Ooooh, that's a lot of xmt power.
-----Original Message-----
From: Matt Jenkins via Af
Sent: Saturday, September 20, 2014 5:47 PM
To: af@afmug.com
Subject: Re: [AFMUG] TVWS Alive or Dead? Was: Re: Dear Cambium
You don't need WiMAX/LTE voodoo for TVWS. Sure there are some advantages
but there are also disadvantages. What you do need is a tight enough
spectral mask and the TX power.
Runcom already had a WiMAX product that operated from 700mhz to 5ghz
built on an SDR designed to use 5mhz or 6mhz channels and supported
channel bonding. They were able to modify their existing product to work
within TVWS frequencies. Using 5mhz channels (or 10mhz for channel
bonding) they were able to meet the spectral mask requirements for TVWS.
Their product already had a call home feature for a central management
system. I wouldn't be surprised if they leveraged most of that design to
work with the database. They didn't have to bring an entirely new
product to market.
One of the other major consideration is TX power. Fixed stations can
transmit 30dbm and have a 6db antenna (36db EIRP). There isn't a lot of
antenna gain available without getting very large. So radios need to
have very high TX power built in. If Cambium were to build a 450 product
they would need to reevaluate their stance on TX power. I would want to
see a radio with at least 28db of TX power available.
900mhz, even in clean spectrum, still doesn't provide the coverage a lot
of this county needs to reach the rural areas. TVWS can go as low as
470mhz. Even the upper channels around 600mhz have significantly more
foliage penetration than that of 900mhz.
I would like to see a DSSS product whereby an AP can TX on two or four
combined channels and RX on a different single channel.
Matthew Jenkins
SmarterBroadband
m...@sbbinc.net
530.272.4000
On 09/20/2014 12:43 PM, Ken Hohhof via Af wrote:
I’m not sure why TVWS has to be based on WiMAX or LTE. Seems to me you
need 4 things:
- comply with the spectral mask including guardbands
- work with the spectrum database
- bond non-adjacent 6 MHz channels (preferably more than 2)
- connectorized for an external antenna
It will be interesting how close the FCC rules for 3550-3650 follow TVWS.
If they are similar, and Cambium modifies their 3650 version of PMP450,
that might be the critical mass for them to look at a TVWS version. That
assumes they could meet the spectrum mask and do channel bonding. I don’t
think there’s any obvious reason to an outsider why that would not be
possible.
I know, you’re going to say that you need the WiMAX/LTE voodoo. But do
you? If you are just trying to go through trees, and you can operate at a
frequency where the trees become translucent to RF, isn’t that enough
voodoo? We’re not trying to do mobile voice+data with call handoffs and
multipath from urban clutter. Let’s face it, if 900 MHz had enough
spectrum for wider channels and wasn’t all polluted from FHSS mesh stuff
like smartgrid, it would be fine without any magical supersauce from the
cellular world.
Maybe I’m wrong about the spectral mask, if the adjacent channel
interference requirement is too tight to meet with DSP techniques alone.
But with an SDR platform you’d certainly have an advantage over trying to
do it with a WiFi chipset. Maybe Ubiquiti’s airPrism technology is an
attempt to move in that direction, although that seems to be on the rcv
side.
*From:* Mike Hammett via Af <mailto:af@afmug.com>
*Sent:* Saturday, September 20, 2014 2:11 PM
*To:* af@afmug.com <mailto:af@afmug.com>
*Subject:* Re: [AFMUG] TVWS Alive or Dead? Was: Re: Dear Cambium
It's not great, but not as bad as you think. Only the NE most portion of
your network doesn't have at least two channels available. That's all
Runcom needs.
It's not significantly more expensive than the PMP platform and delivers
more (throughput and range) than PMP in 900.
-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
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*From: *"George Skorup (Cyber Broadcasting) via Af" <af@afmug.com>
*To: *af@afmug.com
*Sent: *Friday, September 19, 2014 8:27:15 PM
*Subject: *Re: [AFMUG] TVWS Alive or Dead? Was: Re: Dear Cambium
Don't you still have to get an experimental license for TVWS at this
point? Part of the problem here is that we're too close to the Chicago
metro broadcast area. There were no usable channels the last time I
looked at one of the databases. Even in the more rural parts of our
network farther away from Chicago, maybe there's a chance, but it would
be too much investment for too little gains. Current cost of the
available gear, and future gear probably won't be any cheaper. Plus the
HAAT restrictions.
If you can use it, great! I hope you do, and make lots of money at it.
Seriously. But I have a genuine fear that the FCC, who has been throwing
loads of poo at us recently, will change their minds and sunset our
access to the spectrum while it's being auctioned behind our backs at
the same time they control our transmitters via database. We'll see how
the 3550-3700 thing goes.
On 9/19/2014 7:35 PM, Matt Jenkins via Af wrote:
> You think TVWS is dead? I am curious why.
>
> I feel it's a hope on the next hill over not a dream on the distant
> horizon.
>
> We are going to trial the Runcom Wimax product ASAP in TVWS. For us, a
> lot of our area isn't even serviceable with 900mhz (assuming clean
> spectrum). Customer's less than a mile away would have too many trees
> for 900 to connect. Yes, even when that 900 was installed 150ft up a
> tree.
>
> TVWS has the chance to reach lots of those who don't have access to
> broadband or even cell service. For many people a 2mbps/256kbps is way
> better than satellite. They can VPN, game, and VOIP. They might not be
> able to stream high def all day but they can get satellite TV for
> that. Its the trade off for living so rural.
>
> For the past 6 months we have been deploying Telrad WiMAX in 3.65 and
> it's coverage and performance has been phenomenal. I am really excited
> to see what WiMAX applied to TVWS from Runcom can do. There has been
> talk about how the FSK is still a thriving product. In perfect
> conditions FSK provides 14mbps aggregate throughput. Runcom is
> estimating 15-20mbps aggregate throughput in average conditions. You
> also get 2 APs per Base Station with a built in ASN or use a gateway.
