This all sounds very cool, but don’t you need licensed spectrum to operate your own LTE/NR network?
Is there an open/unlicensed band available for this sort of thing, or do hobbyists just “get away with it” by keeping their antennas small and power levels low?
Looks like you’re charged about CAD.04 per MHz per population of the licensed area. Didn’t dive too deep but it might be viable for a small town to put something together, if they’re unhappy with the big providers.
> CAD.04 per MHz per population of the licensed area.
That sounds like a pretty reasonable way to sell spectrum...
I hope this is some time-limited lease and the spectrum eventually goes back to the central government.
I hope that police/fire/military uses have to go through the same process and pay for their spectrum out of their budgets too. Too many other countries just give massive chunks of spectrum to the fire service who will then use it for walkie talkies for 3 fire trucks, when the same amount of spectrum could be used to give broadband, phone and TV to millions of people.
In the United States regulated by the FCC CBRS Tier 3 is available to "general authorized users." You can operate a private lte-network so long as you authorize and follow the spectrum rules. From the FCC Website
> The GAA tier is licensed-by-rule to permit open, flexible access to the band for the widest possible group of potential users. GAA users can operate throughout the 3550-3700 MHz band. GAA users must not cause harmful interference to Incumbent Access users or Priority Access Licensees and must accept interference from these users. GAA users also have no expectation of interference protection from other GAA users. Technical rules for GAA users can be found in Subpart E of Part 96.
Sort of a tangent-- I always wondered what was meant when you see FCC disclaimers (i. e. the Part 15 disclaimers on anything electric) that says "must accept interference."
That seems weird to specify-- interference seems like an environmental hazard to be expected, like saying a light bulb must "accept" a brownout.
Does it mean "it won't be damaged by the expected level of RFI" or is there some sort of "active rejection of interference" they're explicitly forbidding?
The requirement to "accept interference" is legal rather than technical. It means that if the device experiences issues with interference you can't use the normally available method of filing an FCC complaint to get the source of the interfrence shut down.
At chaos communications Congress we usually get a little spectrum for the local network.
But it's not treated as critical as the local DECT network.
I for one wish there'd be software support for the LTE feature that allows a PHY-level broadcast to be received by phones, because we could offer very low latency audio streaming of all the audio tracks (usually German/English presenter, the other via a live-dub, and sometimes french or so as a live dub), so that people could sit in the talk and get their audio via headphones.
The DECT network provided that offering previously, but the conference modules (it was a conference call where you defaulted to being muted) had to go for more base station (controller? For remote radio heads or so, because you'd not want to run RF antenna cables from the box to all the locations...) modules. Also there were doubts as to the PHY being broadcast/multicast or it being unicast, as the latter would be a problem for the large lecture halls due to issues with dividing them into a grid of Femto cells (DECT seems to be badly suited to that approach, but I don't know why exactly).
My idea of a solution would be a wifi distributed-mimo/synchronous base station that feels like one (or a handful) of BSSIDs per frequency (like, a particular 40 or 80 MHz channel in the 5GHz region), but doesn't make clients even aware of roaming happening: ideally it could do full MIMO between the clients transmitting (they listen before they start talking, and don't talk when they could hear someone else saying something (even if they can't make out any words); this could easily be multiple clients with many dozen base stations spread around) and all base station antennas that can get a decent signal strength (trying to make out each transmission even if any individual antenna heard a combination of the transmission, akin to normal wifi MIMO).
Then in the other direction utilizing beamforming to not confuse clients with more overlapping signals than their receive antennas can pick apart (and isolate the signal(s) intended for that client from everything else) (like, talking to clients that are sufficiently far apart so the base can make all other client's signals weak enough to not be a problem for the one client).
Because it can pre-compensate for the base transmissions from the nearby antennas overlapping at the clients, it can simultaneously use overlapping antenna "cells".
And PHY-broadcast (also useful for multicasting) can transmit on all at once simultaneously by being sufficiently synchronous (same mechanism as the echo/reflection/multi-path mitigation of OFDM).
I can’t wait to see what headphone manufacturers come up with in order to let a user subscribe to an LE Broadcast … maybe by jabbing two or three side-of-head hardware button combos, wait 30s, pair again, grr, now repeat x2 for the kids.
>maybe by jabbing two or three side-of-head hardware button combos, wait 30s, pair again, grr, now repeat x2 for the kids.
That would be frustrating. If only the headphones came with some sort of companion device with a touchscreen that could be used to navigate the pairing process.
Just getting the WiFi synced or SDR wifi band transmitters to inject without the base station's proper cooperation would allow synchronous broadcasting of FEC'd UDP streams that an app could easily decode.
Because OFDM allows for multipath even if that's due to literally multiple separate transmitters just synced much tighter than the guard interval (which would probably be 400ns).
Its not unlicensed, you have to apply & get the usage rights from FCC. If some one using at that location, you cant use. Plus, FCC has right to revoke temp or permanently the usage right. If I am not wrong, you have to pay minimal fee. To implement this architecture, you have to connect your private 4G/5G network with SAS service providers.
https://cbrs.wirelessinnovation.org/sas-administratorshttps://www.celona.io/cbrs/cbrs-sas
I thought I was the only one silly enough to do something like this! I've got a Nova 227 tucked away in a corner room of my home facing inwards connected to Magma (was Open5GS).
Did you run into the bug where the default Open5GS bearer rate limit (1Gbps) somehow triggers a bug in the Nova 227 and causes it to run super slow (~7Mbps down/100kbps up)? I found that setting its rate limit to anything else seems to solve the problem and I get 100Mbps/10Mbps with TDD2/SSF7.
Holy hell you might have saved my lab deployment! I need to test this when I get home.
If you haven't, have you considered creating an issue on GitHub over this so they can track it?
BTW -- I've done some really, really cursed things. I actually had ported Open5gs running on one of those little $20 USB LTE modems as a joke on top of Debian. I think I made the world's smallest EPC...
Not going to lie, I was a bit inebriated when I did it so I don't remember the exact stuff involved; my hardest challenge was reflashing the stick's Debian install because I accidentally bricked it.
It involved the openstick hacking[1] to get Debian onto it, and from there because it was just a straightforward arm64 box I had to compile the correct version of open5gs and mongoDB to support it. Not technically complicated, just a hilarious "just because I can doesn't mean I should" project.
The stick itself backhauled onto my home WiFi network, so in essence any cellphone was talking to my eNodeB wired to the network, then over WiFi to the USB stick running Debian, then back over the same WiFi back onto my LAN and out onto the world.
Ahaha yeah it bugged the hell out of me too. Near as I can tell, there's nothing wrong with the Open5GS S1AP message, so filing a GitHub issue isn't the way forward. I did speak with Baicells about it, but their response was sorta... Complex. tl;dr I'm somehow the first one to find it, and they probably won't be fixing it.
If you set the rate limits to ~200Mbps you should be able to achieve max throughput on your 227.
I've similarly run Open5GS on a few cursed systems - shame the OpenStick doesn't support band 48 (though, mine won't detect a SIM card anyway...) - I've snagged a few old Verizon MiFi models that happen to have B48 support in the interim, or my iPhone 11 which makes a good UE.
Is there an open/unlicensed band available for this sort of thing, or do hobbyists just “get away with it” by keeping their antennas small and power levels low?