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Any large in person gathering. Often the very place where the cell networks start to break down due to too many users at once.
Discussion
The problem is that Bitchat is as vulnerable to this, as cellular service.
Many events have dedicated cell towers but even they cannot fit enough capacity in the RF spectrum, so they start dropping users.
Now, this gets worse with Bitchat. The 2.4GHz band is subject to way more interference from WiFi and a lot of other protocols. The band is also pretty narrow too.
To make it worse, Bluetooth only uses 3 channels for advertisements, which is only 3MHz of bandwidth, and is inherently worse due to being a shared medium with no central access control and coordination system.
Now consider a massive stadium. Open air means barely any attenuation. Tens of messages per second, each one rebroadcast by thousands of devices, all talking over each other, with so little bandwidth.
Congrats you have a distributed jammer.
I've heard the same thing can become an issue if there are too many meshtastic units in an area, yeah.
I wonder if the short range of BT is actually a benefit in this case? Low power and low range would cut down on the amount of interference. You wouldn't be dealing with the entire crowd, just people within tens of meters? I've only got 2 nodes to play with so I'm not sure 😂
In open air it’s much worse compared to a closed space. And signals far but not far enough will appear as noise and will still make it worse.
3MHz is also still tiny bandwidth.
It'll be interesting to see. The white paper also mentions Wi-Fi direct being used as a transport. The mesh could auto configure to switch between transports depending on the local conditions. Within the local area some areas would use Bluetooth and others WiFi, with nodes at the edges working as crossovers between the two. That at least let's you get two different frequency bands, if 5ghz wifi is available, plus more & wider channels on Wi-Fi.
While this would increase throughput it would arguably make the problem worse as WiFi is longer range and uses more TX power.
And you still need to pick one channel and stick to it. You can’t listen on multiple channels.
I guess the question is at what point does it fall apart? How many users/area, total users, etc. it's all academic until it's actually in use. Hopefully it gets tested more thoroughly at larger gatherings and can be improved.
thats why 5g uses MIMO and will turn phones into minature cell towers in your pocket in these cases 😂 it burnz
sounds fun
To solve this WiFi has RTS/CTS where nodes coordinate before transmitting.
Basically, if you have 3 nodes A, B, C, and A/C wants to talk to B, they send a request-to-send. Now B can coordinate the transmission order using clear-to-send.
Otherwise what can happen is A and C transmit at the same time and interfere.
MIMO is pretty common on recent phones Wi-Fi hardware, does that help? I know my last two pixels can create a Wi-Fi hotspot while connected to WiFi as the source network. I've no idea if that's part of the Wi-Fi direct standard though.
MIMO does help. But even with MIMO, almost all WiFi radios are single-channel operation.
The WiFi hotspot thing is possible with SISO as wellz
It basically uses the same channel to connect to the network and to host its own.