Comment on Why you can't get a signal at festivals and sports matches
lime@feddit.nu 4 days ago
without reading the article: it’s because every device connected to a cell halves the bandwidth available to each device, and after something like 30-40 devices the cell is full. so it hands over to another available cell, which may also be full. which means that if you’re in a crowd of thousands, your phone desperately bounces off of every cell it can see and keeps getting rejected, boosting its signal every time to get farther away.
this is why we have mobile cell towers for events.
There is a technology called BLE, which together with mesh networking and synchronization of messages instead of routing them can give you connectivity in the middle of big events, without too much signal noise.
Of course other than Briar and that Bitchat thing I don’t know what to use in such situations.
there’s also MIMO, which lets one device relay a 5G signal for another. i don’t think most people appreciate losing battery to route someone elses call though.
Yes, and I meant that BLE doesn’t spread far. Which is good in such an environment.
you can get it to like 50m actually. not reliably, and absolutely not in that kind of environment, but it is possible.
Meshtastic ftw
Its more like a few thousand devices, not 30-40 but ye.
not per cell. per tower, sure, but a tower contains tens of individual cells. i’ve been to places where there are just two or three cells on days where there are a couple of hundred people and the signal just craps out.
Yup.
LTE can support something like 300-400 connections per band and there are 16 primary bands licensed in the US. 5G and mm wave open things up some more, including beam forming techniques that may allow an antenna array to communicate with two devices on the same frequency at the same time.
But at the same time, each carrier only gets some of those bands, and they want to separate bands by physical space so that neighboring cells are using different bands, and in 3 dimensional space there can be a lot of neighbors. And 300 passive connections simply keeping the connection alive are different from 300 active users trying to actively transmit and receive significant data. Plus real world interference will always make devices come up short from the theoretical max performance.
Temporary/mobile towers go a long way, though, for temporary surges in demand, like sporting events. Things have gotten a lot better on game days in certain places (especially small college towns whose populations basically double on game day, with everyone jammed into a single stadium for about 4 hours).
This is the only time 5G is useful
Clent@lemmy.dbzer0.com 3 days ago
I don’t know where you’re getting thsi from. There not how cells have worked since at least 3g, sort of sounds like how consumer grade WiFi hardware operates.
Towers are designed with sectors that are directional and each can support thousands of devices but those can’t handle 10k people at a stadium.
If you had bothered to read the article youd have read they are talking about how stadiums are now using distributed antenna systems (DAS), which is basically hundreds of antennas spread over the venue and fed directly into fiber. Each one is designed to handle a small section. The carriers do need to hook into the endpoint here so this isn’t something that can be setup on a whim.
I don’t see it mentioned but there are also mobile units, cellular on wheels (COWS) are common one and they really easy to spot if know to look for them. Basically a cell tower on trailer that can use microwave for the back haul for when on site fiber isn’t available.
If you end up at a venue and can’t get service it’s because the venue is too cheap to use any of these existing options. They could also be using some outdated antennas, LTE can’t handle as many connections as the new 5G stuff.
lime@feddit.nu 3 days ago
probably from 3g