What happens if someone does not follow the guidelines? --> Smart Citys


(Marioz) #1

Hello,
the more you get in the topic, the more questions come up…

  1. What can be done if the neighbor sends every 2 seconds in SF12 on all channels?
  2. What happens when the frequencies are full / overloaded?
  3. Can someone locate and contact someone?
  4. Is it possible to isolate a node so that it is no longer recognized?
  5. Is it currently working just because everyone voluntarily adheres to it?

The questions I ask myself therefore:
Should a city provide connectivity for parking, garbage and more through TTN, or should it build its own network?


(Arjan) #2

As long as you’re not using SF12, you don’t need to worry, as other spreading factors can still be received just fine.

As for your other points: see LoRaWAN duty cycle abuse.

Unless private networks use a different frequency plan, everyone is sharing the same radio spectrum. So adding gateways to a shared network such as TTN is better, as then more nodes will have a gateway close by and can decrease their transmission power.


(Biermi) #3

In my City (Freiburg in Germany) we have at least 3 LoRaWAN Networks. A private called I-NOVA by our local energy provider (Badenova) used for industrial applications with high security/availability backend, a public TTN Network also sponsored with Gateways (Lorix One) by Badenova and many other users and last but not least another commercial/public network called LORIOT. All using the same frequency plan and hear each other. I see in my TTN console of my gateway packages from the other networks as well as from TTN.
In Germany we have the “Bundesnetzagentur” which is the authority to report violation of the frequency plan. In theory they will come and locate the node and stops the sending, but i’m not sure if it is so, i don’t have seen any case for that. In the past they came and closes some amateur radio sender or cordless phones when they disturbing local television. But that was the good old time with CRT TV.


#4

Different SF are “almost orthogonal”, not “absolutely orthogonal”.

image

At about 19 min. 50 sec.


How many gateways are needed to support 1,000 nodes sending 10 bytes per 5 minutes?
Collision between LoRa packets with different signal strengths
Increasing the number of gateways
#5

If “more” is something more or less “life critical” then better use something other than LoRaWAN and other ISM band wireless technologies. For instance, with LoRaWAN (EU868) you can easily block RX2 with a dozen of LoRa modules still being a good citizen; so I’m not sure it is good idea to use LoRaWAN for street lights, and so on…


#6

Not sure high availability backen can help much if you use very unrealible by design ISM band wireless connections…


#7

with the chance that closed source companies almost go under ? imagine that… nobody can control you’re city lights :sunglasses:


#8

Surely. The problem is that sometime you’ll be unable to control them too.


(Biermi) #9

Yes it is unrealible by design but in the last 8 month, since my gateway and some nodes are running, it happens much ofter that the TTN Backend has a problem (my monitoring alerts me) than a packet from a node is not received by the gateway. I can live with this sometimes instable backend, my use cases working anyway, but i guess in a industrial environment it is necessary that you need a stable running backend on that you can trust it is working.


(Marioz) #12

Hello my friend, I’m from Gelsenkirchen from the Ruhr area :wink:

Yes, I have that feeling too. In these cases, I would connect the gateways with TTN Broker, but at the same time to its own? So you are not dependent on TTN? Is that possible?
We will use LoRaWAN for Smart City, but we also want to support the community.

It would be more for sensor values. So trash can, air quality, parking …


(Constant Joe) #13

Different SF are “almost orthogonal”, not “absolutely orthogonal”.

Readers interested in this should refer to:

“Impact of LoRa Imperfect Orthogonality: Analysis of Link-Level Performance” by Croce et. al.

“On the evaluation of LoRaWAN virtual channels orthogonality for dense distributed systems” by Ferrari et. al.

and

“Mathematical Model of LoRaWAN Channel Access with Capture Effect” by Bankov et. al.


#14

not much to do with the topic title but ok
here’s one too http://www.sghoslya.com/p/lora_6.html


(Arjan) #15

From another topic:

At around 14"20’, transcript and emphasis mine:

The long range is actually also a disadvantage of LoRa. Why? Because when you have a receiver which receives in a 2 km area, if you put a lot ot sensors there, let’s see, if you put more than 2,000 sensors in this range of the transmitter, they almost cannot connect to the gateway because everyone attempts to talk and jumps with somebody else who also wants to talk. So this is one of the problems with LoRa.

In Plovdiv we don’t have this problem. But in Sofia there are a lot of people who try to implement LoRa solutions. And, you know, they work on the license free frequency. But “license free”, this doesn’t mean that this frequency is yours. If you want to follow the standard, you should not talk more than 1% of the time. Nobody complies with this. They just talk until the gateway confirms that it received the message. And they make it impossible for other people to follow the standard.

So I had a customer last week and they said “show me where this LoRa works, because we tried in Sofia and it doesn’t work”. I said, yeah, here in Plovdiv it still works, because there are not so many users who do not follow the standard and just emit content, maximum possible distance, the longest messages they can do, and don’t care about the others.

Of course, the following map only shows TTN gateways, but: I wonder if the above can be mitigated by installing more gateways, to decrease the cell size along with ADR:

TTN Sofia

When one signal is a lot stronger than the other, than it can survive a collision like mentioned above.


(Jeff Uk) #16

I watched/listen to that presentation also and thought much the same - per my comment in the linked thread many focus on just doing nodes and forget to add to the pool of GW’s. Also the map is typical of TTN deployments in that # of GW’s could be increased 40% if the offline GW’s were left on/connected :wink:

With brilliant sense of timing typing this just interrupted by UPS Guy delivering YALG* for me…#26/27 here we come :slight_smile:

*Yet Another Low-Cost GW :wink:


(Afremont) #17

I would think that more gateways and working ADR would go a long way towards solving this problem. Of course spectrum expansion would also help. Right now LoRa has a very small space to work within.


(LoRaTracker) #18

Or maybe not.

For years a solution to traffic congestion has been to build more and better roads.