LoRa mesh networks


#21

Thought better of posting that information


#22

Too late. Already saw it. :joy:


#23

@kieran It was that stingray story, right? I feel like I fell through a Portal post.


#24

After several initial targeted searches, I am still at a loss about one thing that needs confirmation and that no google search seems to be able to uncover. In the US, no significant RF communications can take place without being licensed by the FCC or licensed by Congress directly. Every radio service is made legal only through an FCC section of rules based on laws that govern the given radio service. Even the radio services that do not require anyone to obtain a license to use that service, have a set of rules that govern the use of those radio emissions. If no license is required of the user and the service also does not require a license to be obtained by some business, then that radio service is still licensed. It is licensed by statute for use by everyone. With all of this said, which set of FCC rules govern the use of the LoRa systems? Every search result I’ve been able to get has yielded only answers that say something like “LoRa uses the unlicensed bands”. This is an extremely ignorant answer. After twenty search results in a row repeat this ignorance, you want to pull your hair out. There are no unlicensed bands in the US that are legal for use. Some bands are licensed for use by everyone, by statute. But there are no actual unlicensed bands available for use. If there is no license, that means that no one is allowed to use it. This still doesn’t tell us under which section of the FCC rules the LoRa systems are governed. My guess is FCC part 15. But that is only a guess and may be wrong. This matters greatly because you can’t even play the game intelligently if you don’t know the rules. You need the applicable FCC rule book. Try reading FCC part 80, part 90, part 97, or part 15 (all easy to find from a simple search). Has anyone else here found the applicable rules, statutes, that define the limits of LoRa systems? The chip manufacturer’s datasheets are far to vague. An output power of 4.2mA with -22dbm says little about the actual output power and still says nothing about what the legal limits to output power are.


#25

You could ask a trucker :wink:


#26

From the Regional Parameters document linked previously:

2.3 US902-928MHz ISM Band

This section defines the regional parameters for the USA, Canada and all other countries
adopting the entire FCC-Part15 regulations in 902-928 ISM band.

It goes on to talk (in terms opaque to me) about output power.

Does that help?


#27

A-ha, that is it. It is part 15 after-all. I’ll have to take some time to re-digest part 15. The last time I read part 15, I was sixteen years old and was assembling a 50mW home made am radio brodcast kit. It’s been over forty years since then. I suspect that it’s been updated at least a few times since then. Most people never take part 15 very seriously because in the past it typically only governed children’s toys and old fashioned kitchen appliances for the most part. Even with spread spectrum which can actually operate just below the noise floor, it’s hard to imagine putting such low power devices to practical use in long range radio communications.


#28

This is also an interesting device with LoRa:


But there is no mention of meshing. The mesh part is most interesting for me.


#29

Don’t forget the maximum duty cycle. For example, in the EU you may use the LoRaWAN spectrum up to 1% of the time, so a maximum of 36s per hour and device. So you might want to use it as a means for push notifications, SMS-like messages, but even text-only webpages seem to be unsuitable, especially if you want to communicate without being next to the gateway and the data rate might drop down to 300 bit/s.

Some more information on the limits of LoRaWAN can be found at https://arxiv.org/pdf/1607.08011.pdf


#30

A few things to keep in mind. First is that nobody has written a mesh protocol on top of LoRa. The second is that data rates drop off quickly.

If it were cheap enough it may be worth incorporating for emergency alerts and texts to emergency service when everything else is down. They way the radio protocol is designed is to funnel a lot of little bits of data from many different points (hundreds, thousands), and send back some sort of instruction or confirmation. Which is great for say co-ordinating solar inverters and battery banks, but the host nodes really needs fatter data pipes to talk to each other. So the self-healing isn’t really there.


#31

That’s if you mean real-time mesh comms. But if considering IoT store-and-forward concept (something like z-wave does) then there’s no rate drop (but latency increase) and may still comply with duty cycle requirements.


#32

All of your inputs/thoughts helped me to find real experts out there. Their name is The Things Network. For example and as brought up from @bwildenhain here is their link to duty-cycle. There is Forum as well, etc.

Not Suitable for LoRaWAN:

Realtime data - you can only send small packets every couple of minutes
Phone calls - you can do that with GPRS/3G/LTE
Controlling lights in your house - check out ZigBee or BlueTooth
Sending photos, watching Netflix - check out WiFi

Another one that I found out (having some time this evening) is pretty much official thing, REC 70-03 (the best info, IMHO) on what is going on within EU. @StevenR please take a look at ANNEX 1 link there. Another relevant EU regulations are ETSI EN 300 220-1 V3.1.1 (2017-02) and ETSI EN 300 220-2 V3.2.1 (2018-06). My comments mostly cover ITU Region 1. Useful ITU RADIO Regulations presentation from 2018 is here.


#33

Yes, I’m almost sure that individual license requirement is needed for Road Transport Telematics and movement detection.


#34

Truckers also still use CBRS, which requires no license to operate a station.

[> Anyone, regardless of age, can operate a CB station – except a foreign government, a representative of a foreign government, a federal government agency or someone who has received an FCC a cease-and-desist order that is still in effect. Anyone who is eligible may operate a CB station for personal or business use, in accordance with the rules.

An individual license is not required to operate a CB station and the FCC does not renew formerly issued CB Radio Service licenses;

The FCC service rules for the Citizens Band Radio Service (CBRS) are located in 47 C.F.R. Part 95.](https://www.fcc.gov/wireless/bureau-divisions/mobility-division/citizens-band-radio-service-cbrs)

Like, @richi I’m also interested in short hops over mesh/ad hoc networks


#35

What is really needed is interoperation. Does this product (goTenna) interoperate with other LoRa products - at all levels?

Without interoperation and with a relatively short range, many people can end up with useless islands of non-communication - and the cost of the device is not so low that you wouldn’t care.

I suppose no irony is intended that the product only works with iOS and Android. :slight_smile: Does it have a public API so that someone could more readily use it from a Librem 5? The underlying Bluetooth should be OK but the stuff on top of that is the question.

One thing that seemed to be missing is a dedicated stationary model. (I see that in my part of the world a few people are operating stationary relays but I don’t know what hardware they have.)


#36

Yes interoperability would be great. An open standard would be best. GoTenna is none of that, it is proprietary through and through. But at the moment is seems to be the most used LoRa mesh product.
With goTenna, there is an easy stationary relay function, that is standalone. And at least with txTenna, there is a base station software that can run on a RaspberryPi and can connect to the internet and/or to Blockstream sattellite.
GoTenna offers an API, but you need to apply for an API token in order to use it. I don’t really understand what this is about. I received my token a month after applying for.
I started playing with goTenna, but it is on hold right now:
https://0net.io/1EwAh4KUfGgRw1re7uyrmTUWKZYV9SHVcW/?Post:46:LoRa+mesh+networks+and+Bitcoin


#37

Just musing …

What I was thinking is a different model of hardware. Maybe strip out the battery and charging, add external antenna, and change the form factor.

Another direction to go in would be a remote stationary relay model, which comes with small solar panel, charge controller, and maybe larger battery, mounting brackets, external antenna, and again with a form factor that matches the use case (and obviously outdoor rating).

I get though that having just one model keeps the manufacturing and design cost down.

However

To me this makes it relatively uninteresting for people who are backing the Librem 5. It’s chalk and cheese.

On the other hand, given that the success or failure of mesh depends on density, I suggest that Purism can’t go it alone with an open LoRa mesh product. It really needs a Google or an Apple or an Intel to define standards, build and market a device, and then Purism can create the non-spyware version for those who care. :slight_smile:


#38

I looked into this type of thing really intensely last month because I was going on a cruise ship where communication was at an evil monopoly level of cost and a robbery level of bandwidth. I thought we could use them at times when the family was split up. We didn’t and instead, the family (15 in all) spent 2/3 of our time trying to figure out what to do and where everybody else was going to be.

I doubt it because even within the company they sell a military-type grade, a professional type, and a mere mortal type. Seems you would want the public mesh on its own frequency. Also, I only singled this one out on the other thread because it’s already in the market where the other products are promising dreams.

After reading a bunch of their stuff, it seems the majority of their stationary models are ordinary dongles plugged into solar USB chargers left in high places. They have a map to explore, and some amateurs have 5 to 7-mile radius stationary towers.
https://imeshyou.gotennamesh.com/ (interactive map of public mesh users, not all users)
From reading their site, the 7-mile radius ones are achieved by a simple hack of their product that “breaks the warranty” but they do not discourage people from doing that. They even seem happy that customers are hacking their products.

I didn’t even think to look for interoperability when I was first looking. I’m not even aware of a competitor so there was nothing for me to think of compatibility with other similar items.

=================================================

I’m looking around more now and it looks like Semtech company has the patents on the most important parts: https://www.semtech.com/products/wireless-rf/lora-transceivers
They show Global frequency versions and Continent specific frequency versions. Wouldn’t that mean no matter who fabricated the dongles, the most important part that is patented, LoRa® Transceivers, would have to be interoperable?


#39

The devil is in the details.

For example, it could be that the phy and link layers are interoperable but the network layer is not (and hence by definition no higher layer is in practice interoperable) - so you can exchange packets with a single adjacent node, regardless of vendor, but not either relay (route) or actually do anything with the packet.

Or it might not even be as good as that, for example, because there are too many protocol options even at the lower layers.

I note also that the goTenna web site talks about options that are only available with a subscription and intentionally limited functionality otherwise. Hmmm.

There is always tension between a competitive advantage in the market and encouraging wider adoption. My opinion, for what it is worth, is that if Semtech wants this to be a success then they need to drive total interoperability even if it doesn’t suit the agenda of manufacturers using Semtech’s chips or patents. That could mean having formal interoperability certification.

In some respects it reminds me of the internet before there was the internet.

I suppose the military may want their own frequency but it is not as if this would prevent jamming, and the military already have the option of having their own frequencies.

One potential use of this is in disaster areas where all terrestrial telecommunications infrastructure is dead. In that case, it would be more helpful if everyone actually can communicate with everyone else, including the military.

Unclear how a “professional type” might differ from a “mere mortal type”.


#40

There’s already that sort of purposed long (and short too really) range radio capabilities but I expect stations could also act as dual nodes in denser areas for add on wifi last relays to be used for a more casual purpose. Soooo hungry for more ham!:cut_of_meat::bacon: