When I travel, I try to use an eSIM that uses a network my home provider partners with. This seems to improve the chance that voice and data over LTE or 5G NR work simultaneously.
Dual SIM Dual Standby (two or more SIMs, one radio) is cheaper, less battery, less space, and usually good enough. It's literally a few dollars, not 200-300.
DSDA in 5G is rare, and I can't reliably find a phone that can do it in EU or US (I can find higher end chipsets that can do it, but phone vendors don't seem to follow through with it). Usually it's 4G+5G or 4G+4G.
Support for VoWiFi is a bit weird. Some operators don't allow it outside of your region (for example, the EU), some others will allow it and even bill you as if it were a local call made from your country.
Also, although it's in theory made only for working through WiFi, seems like if you have a second SIM or eSIM with a data plan (for example, a travel SIM local for the country you're on vacations) and some combination of phone and/or operators, it can use the second SIM as the data provider for WiFi Calling.
I was using a Samsung S5 running LineageOS for a while with Google voice for calls, but the no 911 thing is one of the main reasons I finally moved to a different phone. The S5 supports VoLTE but only with stock firmware.
no. Too expensive.
So yes, it's "too expensive" because it's higher than $0, but it's not "too expensive" as in it would cost a lot.
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-...
Maybe ok for your garden camera where the authorities just don't care. But no go for any industrial usage.
If you need consistent MB range traffic for cameras I wouldn’t advise it but for low (5kbs) traffic it can be attractive. A few thousand bits can encode quite a bit of information. Don’t be fooled by the “kbs”.
Really there should be a world wide 900-1000MHz ISM band.
I was so excited when I discovered it a few months back after struggling for years to set up reliable wifi for outdoor robotics, only to realize we can't have nice things. The struggle continues.
Seriously. Only rich nerds in SAN FRANCISCO are using it.
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.
It will still try to roam, it will still cause issues.
A lot of the roaming logic is in the clients. Newer android and iOS versions have gotten better but there are tons of old and new devices with poor roaming logic and capabilities.
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.
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?
The AVM Fritz product line of consumer modem/routers all include a DECT modem for registering extra handsets for voice but they have their own proprietary handsets that support TCP/IP over DECT for things like audio streaming or sending extra media like a caller photo.
Your old devices won’t magically get more reliable because WiFi 8 comes out. You will benefit from this after it comes out by migrating to WiFi 8.
Meanwhile, you can benefit from existing reliability enhancements by upgrading to WiFi 6.
If your response to that is ‘I can’t use WiFi 6’ then presumably the putative benefits of WiFi 8 are even more remote.
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.
Sometimes we forget that for the communication to be reliable, signal must flow both ways. Clients will happily connect to far away APs, but won't be reliably heard back.
Solution is to use more APs and lower their radio tx power. A lot of customers push back on the approach because they have only one gaming router monstrosity in their country home and it works perfectly, not understanding that their downtown office with 150 devices have nothing in common.
DECT is a much, MUCH more old, simple and robust protocol. Modern signal processing tech can get you insanely far there.
You have a bunch base stations forming a logical channel with a single uplink frequency, and either a single downlink frequency on which every base station is precisely synchronised in frequency and time (simulcast), or multiple downlink frequencies (a multicast system).
A comparator selects, or votes, the highest quality signal from the base receivers based on either lowest noise or lowest BER, and then repeats that through all of the base transmitters simultaneously.
At the same time, in a multicast system, the mobile scans for and selects the base transmitter with either the highest RSSI or lowest BER.
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".
We have industrial SIMs with our own APN and get a IPSec tunnel to the Telco where we have a dedicated network to see our devices.
But they do use commercial wi-fi devices, albeit with a focus on configuring security correctly.
I do kind of want to play with this.