Folks - I'm new to the group here, and not yet running a node on the network. I support EmComm for Los Gatos / Monte Sereno CERT here in the Silicon Valley, and we are looking for ways to interconnect our Incident Command Posts to our Emergency Operations Center via an IP network. These ICPs are nothing more than 8' x 10' or 10' x 12' sheds, often with limitations on the height of a dish/antenna which can be used. Coverage mapping makes it clear that there is no hope of getting LoS to support 5GHz links to a main site or between the ICPs as a mesh.
One option we are considering is use of 802.11ah -- this ia a variant of WiFi defined for use in the 900MHz band, for longer range and lower throughput. Specifically, longer guard intervals for higher-latency multi-path, much lower channel BW, more provisions for redundancy in coding for robustness, etc. With moderate gain external antennas, we could stay within the +36dBm EIRP limit for unlicensed operation... but we could operate under amateur license with much higher gain antennas and even external amplifiers.
It seems that the 900MHz band plan would allow for this usage, though we have to recognize that we remain a secondary user on the band and have to address concerns about interference from primary users. I am concerned, though, that we must me missing something here since AREDN hasn't adopted this as a technology option. I don't know if that is because of radio or licensing, or maybe because of lack of access to custom firmware and software solutions for the available hardware.
If there is anyone on the AREDN team who has looked into this, I'd love to learn more about what you found.
Many thanks for the discussion,
Brian Whitaker, AG6WR
LG/MS CERT, ARES/RACES operator
One option we are considering is use of 802.11ah -- this ia a variant of WiFi defined for use in the 900MHz band, for longer range and lower throughput. Specifically, longer guard intervals for higher-latency multi-path, much lower channel BW, more provisions for redundancy in coding for robustness, etc. With moderate gain external antennas, we could stay within the +36dBm EIRP limit for unlicensed operation... but we could operate under amateur license with much higher gain antennas and even external amplifiers.
It seems that the 900MHz band plan would allow for this usage, though we have to recognize that we remain a secondary user on the band and have to address concerns about interference from primary users. I am concerned, though, that we must me missing something here since AREDN hasn't adopted this as a technology option. I don't know if that is because of radio or licensing, or maybe because of lack of access to custom firmware and software solutions for the available hardware.
If there is anyone on the AREDN team who has looked into this, I'd love to learn more about what you found.
Many thanks for the discussion,
Brian Whitaker, AG6WR
LG/MS CERT, ARES/RACES operator
If you can set up a pair of 802.11ah devices as an Ethernet bridge then you could bridge two AREDN network with it. It's apt to be agonizingly slow though.
Orv W6BI
Are there any concerns about the use of the band the way I am thinking? Even outside of AREDN, I haven't heard of other EmComm teams making use of HaLow and wonder why.
Brian, AG6WR
"unless OpenWrt supports a device AREDN most likely won't either, as it's derived from OpenWrt." Orv
Hi, Brian:
IMHO, "discussion with equipment vendors" does not seem to be in AREDN's mission.
Actually, it is the equipment manufacturers choosing the hardware.
Some hardware uses proprietary firmware, some uses open source firmware.
The choice of hardware i$ likely what make$ the mo$t $en$e to manufacturer$.
AREDN firmware is open source...it is not copied/modified proprietary firmware.
If the manufacturer chooses to use hardware which uses open source firmware and
OpenWRT releases open source firmware for a device, then it may be possible for AREDN to build firmware.
Not every device manufacturer builds devices with open source hardware.
It seems to me that the Amateur Radio market is too miniscule to sway choices made by manufacturers.
73, Chuck
Your comments about wanting to get mesh into a trailer are familiar to me. When a trailer has to go anywhere it is needed this is difficult at best.
If you have mesh at a high point in the county with good backup power, then if the trailer itself is not able to be reached you can easily build a battery operated relay site with a couple of antennas on a collapsible mast. I like to use DJ style dj stands as they are everywhere and affordable tripods. The only problem with doing this is physical security of your gear ... if you setup the equipment on a nearby rooftop or nearby hilltop and leave it running on a good battery it could disappear.
The other consideration if there is a rooftop, hilltop ??? nearby the deployment area is to setup the AREDN gear there but instead of relaying a mesh signal to your trailer, at THAT POINT have the last leg of rf be part 15 but with a lot of power 2.4 or 5.8 ... as your users are going to be using LAN anyway if you can throw the last leg as part 15 then you can use it inside or outside the trailer.
Think out of the box and put in a relay station. If distances to your fixed AREDN node aren't that long, a somewhat forgiving node (not laser tight beam) will work fine. 900mhz is spendy and not supported much in the AREDN world.
Ed
() Chuck NC8Q: slow is OK; my group's goal is not to meet AREDN performance. We are replacing current radio voice channel communications and 1200bps packet radio BBS for moving simple forms. ~50-100kbps throughput would be a significant upgrade.
() Chuck NC8Q: on OS support and firmware open/closed source -- one of the key chipset vendors in the space (Morse Micro) has Linux drivers. That would mean those are open-source, right? I need some basic help on how the develpment here goes -- does this AREDN team go and adapt each chipset driver (firmware) for Linux such that it works on OpenWRT? Is AREDN operating at Layer2 such that the use the stock driver from the mfg and are doing all the magic at the network level?
() Ed K7EOK: On trailers -- I think there is a misunderstanding on this one... we have no specific need for a trailer. Our EOC is a Police building and our ICPs are stationary sheds. Both are locked up well enough that we seldom have issues with theft. If we get our network up and running, we do have a good site we'd use as that relay point to join the rest of the AREDN network.
() K6CCC: I didn't understand that there were any licensed users in the 902-928 band. I have not yet done a throughput test here nor have I thrown up an antenna and looked on a spectrum analyzer for just how crowded this spectrum is around here. Agreed that it might be totally unfeasible for this reason.
Brian AG6WR