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
Hi, Brian:
My concern with your thinking is as 'an IP network', the throughput would be too slow to support an idle AREDN network.
IOW, an 802.11ah network might struggle to pass 1 audio circuit.
Perhaps it might be fast enough to link Winlink Express stations.
73, Chuck
"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
Like AG6WR, I'd like to learn how AREDN works from a network standpoint, and what the performance expectations actually are. I think the dim view of .11ah in this thread is unwarranted, but of course it's my $dayjob.
Brian- I'm at HQ in Sydney at the moment, but would be happy to catch up with you when I'm back in the Bay Area to support some experiments, including with a couple of AP/Extenders if it's useful.
Thanks,
Zandr, N6MOD
"Any consideration for 802.11ah (HaLow) for some links? "
"I'd like to learn how AREDN works from a network standpoint, and what the performance expectations actually are. I think the dim view of .11ah in this thread is unwarranted, but of course it's my $dayjob."
Hi, Zandr:
Thank you for your post.
You posed 3 sub-topics in a discussion of 802.11h in this AREDN Forum.
network standpoint:
IFAIK, AREDN is used to create an IP transport network.
performance expectations:
AREDN performace expectations are in the Megabits per second throughput range.
dim view of .11ah in this thread is unwarranted:
because 802.11h throughput is 1000 times less.
It might make sense to transport 802.11h data over an 802.11b,g,n,ac network, but
it might make little sense to transport 802.11b,g,n,ac data over an 802.11h network.
802.11h throughput might be less than required for a single 802.11b,g,n,ac link maintenance throughput.
73, Chuck
> because 802.11h throughput is 1000 times less
I think you might be confusing 802.11ah with LoRa. MCS 7 in 8 MHz is 32.5Mb/s, and MCS 9 gets to 43.3Mb/s (PHY rate, throughput depends on protocol, of course.)
I speak for many when I say we'd be very excited to have HaLow on AREDN. There's daily discussion of this in the AREDN Slack. I couldn't care less about a single negative opinion since there are real world problems HaLow would solve in the Southwest, even with some known issues like the 53uS time slot derived range limit (as-built). Being able to extend the time slot window to selectively increase range, or incorporating GPS-disciplined oscillators for precision slot coordination, would be even better.
We're transitioning from OLSR to Babel right now for the network routing protocol, so how AREDN works under the hood is somewhat in flux. If you have any particular questions I'm sure the lead dev Tim, KN6PLV, would be happy to answer them.
Regarding performance, for scale, the fastest remotely comparable amateur radio solution to IP-based networking is New Packet Radio, which I don't believe can exceed 500 kbps. We're looking at HaLow in Arizona to handle challenging terrain where we may almost have line of sight, but foliage or minor obstacles impede the use of higher microwave bands, which stop working entirely. This is especially true in Northern Arizona where pine trees are abundant and AREDN would be particularly useful due to frequent wildfires and extreme Winter weather. Personally I really want to try it with a very high gain yagi <-> yagi setup to see what can actually be achieved in specific areas. All of the testing I've seen so far has been with relatively low gain omni <-> omni antennas.
HaLow is also appealing in congested spectrum environments since it can provide useful speeds (even 2 Mbps is useful if reliable) with very little bandwidth. The older Ubiquiti Rocket M900s did go down to 3 Mhz, but that equipment is thoroughly sunsetted at this point
Let me know how I can help here. We are currently in the midst of open sourcing our drivers, and it sounds like a key requirement to enable AREDN is to get support for HaLow upstreamed into OpenWRT. All of our dev kits are based on OpenWRT, but our drivers are currently out-of-tree.
Thanks,
-Zandr
If we need anything more than that, I'm not currently aware of it. Orv (W6BI) or Tim (KN6PLV) would be the ones to ask as the project manager and lead dev, respectively. I'm a bit flakey on checking the forums right now since I'm in the middle of moving, so they'll be more reliable points of contact.
Glenn
Orv
W6BI
AREDN Project Manager
What matters to me most is not highest connection speed, but that it is true TCP/IP so there is some accountability for packet delivery. If a marginal site can get onto AREDN and send Winlink messages, and do file transfer ... that's enough for me. I don't consider the IP phones important to our em coms mission, as we already have lots of 2m and 70cm channels to work with.
Our current long term plan is to have AREDN available at every fire station in the city ... but the fire stations weren't located for rf lol. So if this is a functioning but slower speed link on the network and is reliable and maintainable ... I'm willing to try it. I would want to find out the antenna patterns available and see if the 900mhz stuff needs to be a parallel network on our tower sites, or if we can put relay sites with a hybrid 5ghz/900mhz with perhaps a yagi pointed at our hard to serve locations. In other words ... interesting ...
Ed
So yes, it's a WiFi MAC, and you can run IP over it just fine.
There are multiple chipset vendors, though I obviously think ours has advantages. I actually learned about AREDN because some folks using our competitor's chips did some 100km mountaintopping. They were hyping it as WiFi, but they were way past unlicensed EIRP.
Maximum Power: Amateur stations may not transmit with a power exceeding 50 watts peak envelope power (PEP) in this band if operating within 241 km of the boundaries of the White Sands Missile Range.
Outside this restricted area, the general limit for amateur operations is up to 1.5 kW PEP, provided that only the minimum power necessary for communication is used.
Edit PS and while we're asking questions, is the amateur use of this band also subject to the latest FCC issues like Meshtastic is? Last I heard some commercial firm wanted the spectrum to make a land based GPS system for auto navigation.
https://www.eff.org/deeplinks/2024/09/nextnavs-callous-band-grab-privati...
Tim was in contact with Rig Expert, who make a 915 Mhz amp which works well with Meshtastic devices. They stated that amp doesn't work with HaLow, but suggested they would be able to design such a product.