alt Hacker NewsWe need reliable, real-world ~20mbit/s for our warehouse scanners, not 382722 theoretical Gbit/s 5cm from the access point. And roaming that works instead of stupid clients clinging to somewhere or being thrown into a reconnect loop when the AP tries to get them to roam. I know this is theoretically possible today. But in the real world, I have inherited the setup, so AP locations are fixed for now, clients are some random old handhold motorola android devices and interference is high.
In comparison, DECT has been flawless in the same space. Set and forget, just works. I always wondered if we could have a kind of DECT proxy on the LAN, and have the ERP application talk to that proxy using DECT... I mean, it's a few EANs and stuff, DECT could handle this easily.
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Perhaps you can try DECT NR+ the new reincarnation of DECT and also backward compatible with the original DECT [1]. It can also do roaming.
It's under 5G standard but for non-cellular connectivity that means you can use it without base-station like Wi-Fi direct. It's geared toward IoT but its data rates are from 1 Mbps up to 1.3 Gbps depending on the operating frequency and the type of modulation being used [2].
[1] DECT NR+: A technical dive into non-cellular 5G (30 comnents):
https://news.ycombinator.com/item?id=39905644
[2] Technology: DECT NR+ [pdf]:
https://www.vdma.eu/documents/d/group-34568/technology_dect-...
I was recently made aware of WiFi HaLow. Official standard, ranges into the hundreds of meters. Speed suffers at long ranges of course, but still respectable (50-100kbs).
> We need reliable, real-world ~20mbit/s for our warehouse scanners, not 382722 theoretical Gbit/s 5cm from the access point
Those two are the same thing, though!
Literally nobody is hitting those insane theoretical transmission speeds. Heck, most access points don't even have the uplink for it. So why bother? Easy: because it provides you margin. A 10Gbps link degrading to 100Mbps due to poor signal quality is a lot better than a 1Gbps link degrading to 10Mbps when you are trying to achieve that 20Mbps connection. The expectation is that your signal will degrade, so it is all about starting with a good-enough spec that you'll still have a reasonably-usable connection left at the end.
It's a similar story for multi-client connectivity. A 10Gbps link might sound overkill for a 500Mbps residential internet connection, until you've got legacy and poor-signal-quality clients taking of 95% of the airtime for 5Mbps of data. Being able to still get enough data through that remaining 5% airtime to saturate your internet connection is incredibly useful.
And before you praise DECT too much: its 2020 revision allows for a 1.2 Gbit/s transfer rate, with all the fancy stuff like MIMO and beamforming you might know from Wifi. Quite excessive for a few simple phone calls, wouldn't you think?
I've had similar issues with clients (Blink camera sync modules) connecting to far-away APs instead of the much closer router. I could not force them to connect directly to the router no matter what.
Turns out the 2.4 GHz radio of my router had died (Fritzbox 7590, apparently a common issue), thus forcing 2.4 GHz-only clients to use those other APs.
Yeah you can run stuff through DECT I'm not sure what handheld suitable gateway you'd use and strap to the holster of the associated scanner, but otherwise...
That said, in theory at the level you're asking for it'd be acceptable to run the system as a single frequency network by using the AP locations as remote radio heads and just not telling the handhelds that there are multiple APs in listening range.
I'd probably aim for using the wifi support mechanisms to dynamically fake nearby APs as "mimo antennas" from the POV of the handheld, but not doing so would also suffice, just transmitting from the one AP that's nearest to the specific handheld/client would already basically do the trick and could probably run with hacked firmware on commodity AP hardware basically turning the entire setup into a soft-MAC with that very software juggling the army of radios.
The setup btw. would not have the clients aware they're dealing with more than one radio on the other side.
You could be forced to ask/ping the client from multiple APs one after another if you've not heard from it in a while and it moved, but otherwise, you just rely on hearing it from multiple APs and tracking it so you don't have to make APs across the facility speak up and risk interrupting other clients that try to get a word in.
Oh, and ban by building ordinance usage of any other Wi-Fi on the channel your doing this on, or that's gonna eventually get you problems with congestion.
I hadn’t realised that DECT is still in use. It was pretty good in its heyday so glad it’s survived.
Another option here might be Private LTE in the CBRS band.
How much data do the scanners really send backwards and forwards?
I feel like a lot of the problems people try to solve with wifi and dozens of access points could be better solved by a 450MHz-ish transceiver up on the roof with a downfire turnstile, and 9600bps radio modems in everything.
I'm going to embroider some red hats, going to put on them "MAKE SLOTTED ALOHA GREAT AGAIN".
> or being thrown into a reconnect loop when the AP tries to get them to roam
The AP does not have visibility into what the client actually sees, and no, a coordinator that has knowledge what the APs see isn't that much better.
Imagine a situation with two APs and a client being in the middle of the two in a RF-impeded situation (i.e. your typical office building). AP1 may "hear" the client better (i.e. it gets a higher RSSI and SNR), but the client may reject it in favor of AP2 because the client sees a better signal coming from AP2 due to reflections, a powerful RF signal from a floor above interfering with the channel of AP1 or God knows what else.
RF is a weird world.
LoRa is quite nice for this in the lower frequency bands, and the bandwidth should suffice for this sorta thing. And the tech is super cheap to build and maintain, both hardware and software is open source.
Warehouses, factories, etc need private 5G, not Wi-Fi.
DECT or DECT-NR+?
I do kind of want to play with this.
You need to enable automatic updates. /s
Here's another one for you: today I found out that my dual-sim android phone has a single radio that is shared between the two sims. So when you are on a call, the 4G/5G doesn't work on the other sim, likewise, sometimes the the voice sim is unavailable while the other sim engaged with 4G/5G things... which is just stupid. Can't they just add two radios/chips (like many wifi AP's....)? So the whole setup on a consumer phone is actually quite unreliable because of reusing a single radio. I thought it was my buggy code, but nope, just the radio being shared and the mobile operator seeing the sim as offline. Crazy.