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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

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?

jetsnoc 4y ago
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.
- myself248 4y ago
  Have you figured out how to get a SAS connection as a GAA user? I can't even find a price list.
- hakfoo 4y ago
  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?
  - jgerhardt 4y ago
    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.
seanbrodie 4y ago
The US have unlicensed spectrum available for "Citizens Broadband Radio Service" (CBRS) which can support 5G and LTE.
- Ballu 4y ago
  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-administrators https://cbrs.wirelessinnovation.org/sas-administrators https://www.celona.io/cbrs/cbrs-sas https://www.celona.io/cbrs/cbrs-sas
  - seanbrodie 4y ago
    Thanks for clarification. I'm not in the US so am not familiar with the specifics.
  - kotaKat 4y ago
    Indoor CBSDs don't need a SAS. You are fully legal running a B48 eNB inside your home at low power without even touching the FCC. I'm doing this with Open5GS and a Baicells Nova227 that's running at low power indoors as it's both an indoor and outdoor-capable unit.
    - FrankPetrilli 4y ago
      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.
      - 4y ago
stasmo 4y ago
You can see the licensing fees here for Canada. https://ised-isde.canada.ca/site/spectrum-management-telecommunications/en/spectrum-and-telecommunications-fees https://ised-isde.canada.ca/site/spectrum-management-telecom... 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.
- londons_explore 4y ago
  > 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.
- notatoad 4y ago
  huh, i didn't realize spectrum was so cheap. that actually makes something like this really viable for use in unpopulated areas.
namibj 4y ago
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).
- avidiax 4y ago
  Bluetooth LE is developing a broadcast solution like this. Eventually, commodity headphones will be able to subscribe to such broadcasts. Time to short the companies that make lecture hall assisted audio devices and museum audio guides.

jetsnoc 4y ago

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.

myself248 4y ago
Have you figured out how to get a SAS connection as a GAA user? I can't even find a price list.
hakfoo 4y ago
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?
- jgerhardt 4y ago
  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.

seanbrodie 4y ago

The US have unlicensed spectrum available for "Citizens Broadband Radio Service" (CBRS) which can support 5G and LTE.

Ballu 4y ago
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-administrators https://cbrs.wirelessinnovation.org/sas-administrators https://www.celona.io/cbrs/cbrs-sas https://www.celona.io/cbrs/cbrs-sas
- seanbrodie 4y ago
  Thanks for clarification. I'm not in the US so am not familiar with the specifics.
- kotaKat 4y ago
  Indoor CBSDs don't need a SAS. You are fully legal running a B48 eNB inside your home at low power without even touching the FCC. I'm doing this with Open5GS and a Baicells Nova227 that's running at low power indoors as it's both an indoor and outdoor-capable unit.
  - FrankPetrilli 4y ago
    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.
    - 4y ago

stasmo 4y ago

You can see the licensing fees here for Canada. https://ised-isde.canada.ca/site/spectrum-management-telecommunications/en/spectrum-and-telecommunications-fees https://ised-isde.canada.ca/site/spectrum-management-telecom... 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.

londons_explore 4y ago
> 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.
notatoad 4y ago
huh, i didn't realize spectrum was so cheap. that actually makes something like this really viable for use in unpopulated areas.

namibj 4y ago

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).

avidiax 4y ago
Bluetooth LE is developing a broadcast solution like this. Eventually, commodity headphones will be able to subscribe to such broadcasts. Time to short the companies that make lecture hall assisted audio devices and museum audio guides.