Introduction to open source private LTE and 5G networks | Hacker News Reader

Introduction to open source private LTE and 5G networks

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I'd love to setup a small scale network for personal use, but the elephant in the room is licensing.... Is it actually possible to formally license a DIY LTE network? (Or AMPS, 2G, 3G). In the UK, for example it is possible to get experimental licenses in principle, but I doubt it would be possible for an individual to legally operate a permanent or long term network on/near commercially allocated frequencies?

I think there needs to be a push to make it possible. It's kind of tiring having big corporations being the only ones who can do things.

There are already a lot of things that are feasible without any license. In Europe/CEPT, you might have a look at all bands under the provisions of ERC Recommendation 70-03 (https://docdb.cept.org/download/2464).

However, those provisions are made in order to ensure a good/fair access to anyone, and therefore to prevent a single user or single technology from overusing those bands which are meant to be shared. For that purpose, there are associated restrictions (in terms of power/EIRP, duty-cycle) and/or mandatory sharing approaches (Listen-before-talk, detect-and-avoid, etc.). In the case of Wi-Fi, CSMA/CA is a form of listen-before-talk.

Unfortunately, mobile technologies defined at 3GPP (GSM, HSPA, LTE, NR) are not designed to be used in such a way (i.e. they don't have any sharing mechanism such as LBT and they require _by design_ dedicated/licensed bands), which by the way implies some kind of specific coordination at the country borders where two operators are using the same channels... (you might look at ECC recommendation 15-01 for an example of PCI sharing).

LAA is a way to have an LTE carrier within the (shared) 5 GHz band, but it has to rely on an anchor carrier for signaling, which requires licensed spectrum. Multefire is a fully-unlicensed solution, but I doubt many UEs (smartphones) support it, and anyway because it must implement the same power limitations and LBT as wi-fi in order to comply with regulations I doubt it would be much better than wi-fi... (maybe it would in some specific case where deterministic QoS is important)

One more thing : keep in mind that a typical 3G/4G/5G macrocell site (e.g. around 65 dBm EIRP per carrier) is something very expensive : your mileage may vary but it can easily be around 100000 € / site when some construction is required.

>LAA is a way to have an LTE carrier within the (shared) 5 GHz band, but it has to rely on an anchor carrier for signaling, which requires licensed spectrum.

I want to add, as I said in my last comment that 5G NR allows for 5Ghz to be used as primary carrier, it was controversially included in the standard. A study from earlier this month showed LAA apparently doesn't play too well with wifi nearby: https://www.cs.uchicago.edu/news/article/laa-wifi/

In general, cellular technologies have been designed against assumptions of a clean (or at least exclusively used) RF channel. 4G and 5G are deployed with frequency reuse between base stations, which implement the same standard and can coordinate their emissions and scheduling of clients (both in time and frequency) to minimise interference.

WiFi is a whole different kettle of fish - it's designed to be used by multiple independent access point operators simultaneously, with the ability to change frequency if needed based on the interference observed. It's designed to try to deliver good performance by listening before transmitting etc, to avoid transmitting over another device, to avoid a tragedy of the commons scenario where selfish devices end up rendering WiFi unusable for everyone (including themselves), through refusing to yield time to devices transmitting on other networks.

NR-U and LAA etc don't generally play according to the same rules, as they're standards arising from the world of exclusive spectrum access, and coordination of base stations by one operator - in the world of cellular, the base stations allocate uplink channels for their clients. That doesn't work in WiFi with multiple networks in the same approximate location, hence they need to try to prevent interference and cross-talk.

In the UK there are 2 ways to get access to long-term spectrum. It's also usable from a bands and handets perspective!

1. Shared access licence. There's 3.3 MHz (duplex paired) of former DECT guardband available for local use at the top of the 1800 MHz band. This should work fine to run 2G or 4G. There's 10 MHz of TDD at 2390 to 2400 MHz, indoor use only I believe, and most useful for 4G. There's also 3.8 to 4.2 GHz which allows outdoor use, and is dedicated shared spectrum for 5G. Transmit power limited aren't enough to run a big commercial network, but are enough to deploy a private network on a campus or private site.

The former two should be widely supported on handsets. The latter (5G option) is aligned with band N77.

2. If you're in a rural area, get a local access licence to "take" existing operator spectrum and use it legally, with 3 years max tenure. It can be renewed if the operator has no intention to use it. Operators don't like this, as they see spectrum as their owned property, but this isn't the case, and they only have a right to use it...

The process of getting a local access licence is deliberately complicated by operators as they don't want you doing it, but it can be done. You need to understand the technology and commercials of the industry though to realistically be successful. Some operators want you to talk to them first, others want you to talk to Ofcom first. If you know what you're doing, and make a strategically selected request for spectrum, it can be done. You can operate a commercial service in this spectrum, but you have to be clear to users the time-limited nature of spectrum access.

Going forward though, it's clear from Ofcom's own priorities that a more dynamic nature of spectrum allocation and utilisation authorisation is a priority and likely to be coming down the line - it's been a work item the last couple of years. Once that comes, we could see easier ways to access spectrum. Realistically though, operators will do what they can to make spectrum access complex, to preserve a final moat in a market of 10+ years of continued reduction in average revenue per user.

What would be the cost of this though? I thought these things tend to get bid up to the range of billions of dollars

These licenses are in set-aside bands specifically for sharing. You're talking about 80 GBP per year for up to 10 MHz, and 80 GBP per year for each additional 10 MHz.

https://www.ofcom.org.uk/manage-your-licence/radiocommunicat...

This isn't nationally auctioned spectrum (which gets bid up to billions, then operators have to pay those fees into government coffers).

Whoa!!!! That is not expensive! I did not know that

Yes this was my question… The FCC is pretty aggressive about keeping people off frequencies they don’t have a license for, how does that work in these types of environments? Especially something like a college campus, where you have 10,000+ students who would all need their phones to be reprovisioned… not to mention how would it work if you walk off campus? LTE/5G isn’t really great at working with multiple networks… it just wasn’t set up that way…

Does it mean that the protocol has big corporation monopoly built in by design? I am not familiar with the details, but by the sound of it why is this even legal?

Not really, anyone can own spectrum, in the last few years its gotten really expensive as it's become more important to building a robust network but historically it wasn't that hard to license an small band in your area.

Radio spectrum is a shared resource that for many use cases needs exclusive allocation to work well - if one person/organization is using a frequency band in an area, they need to be the only ones who can use that frequency band there. Think TV or radio stations; if someone else is transmitting in the same channel, then it just disrupts the broadcast. So most such spectrum is allocated (often through auction) and then whoever has that allocation is legally granted a monopoly on the use of that spectrum, enforced by government who will prevent anyone else from using that spectrum with fines and even physical interference (finding, disconnecting and confiscating the violating transmitters) if needed.

Transmitting over radio waves is a highly regulated privilege. There are a few ranges that are open to public (i.e. the bands used for Wifi and BT) with devices that need to be certified to ensure that they transmit only in the narrow permitted ranges, but in most frequency ranges (including the LTE/5G ranges) it is illegal to operate a transmitter without an explicit license.

This was true decades ago but for the vast majority of modern applications users would be just fine sharing spectrum and dynamically negotiating/avoiding each other. If you go look at an SDR waterfall you'll find that vanishingly little spectrum is ever in use but almost all of it is reserved for various interests, mostly using legacy analog modes.

We need more and wider unlicensed bands, there's no reason for most of this regulation anymore.

People pay money, sometimes quite a lot, for exclusive access even if it’s infrequently used exclusive access. It’s quite common in many industries beyond telecom as well. Do you not believe that preference exists?

You could simply host your network on unlicensed spectrum.

AFAICT -- and I would be happy to see counter-evidence -- all the unlicensed spectrum suitable for LTE or 5G is in the 5-6 GHz frequencies. The physical characteristics of transmission don't change, so one might as well just deploy the cheaply available 5GHz wifi systems -- you don't get an advantage by using LTE or 5G protocols.

i suppose if you only had relatively low data rate applications you could use 900MHz, but there's a dearth of CPE. 900MHz unlicensed has slightly more bandwidth than a single 2.4GHz wifi channel.

You can probably drop it down some more and use tvws spectrum. Probably will be alone there

TVWS channel allocations often don't align neatly with duplex paired 3GPP bands, meaning you might need multiple adjacent TVWS channels.

In addition, in many countries the TVWS regulations only cover specifically authorised devices which adhere to TVWS standards (which 3GPP doesn't), and create a whole host of challenges for the client devices (handsets), which don't understand TVWS rules, and need their transmit power to be controlled by the base station, which isn't necessarily aware of the client location, or authorised within TVWS rules to query the TVWS database on behalf of the client.

Might as well use 8.0211ah there. It's not like you can get consumer equipment that supports the 900 MHz ISM band for LTE.

Rules are different in each country of course but most unlicensed frequencies can only be used with mechanisms that leave space for other users (networks) like listen before talk or restricted duty cycles. Cellular technology isn’t built with shared access to spectrum in mind although there is/was some effort to add it (LTE-U, 5G-NR-U).

I recently deployed an LTE network at a research station in Greenland. Licensing ended up much easier than I expected (the Greenlandic government almost immediately granted the license for LTE band 8), but this is in a place in the middle of the ice sheet hundreds of miles from the nearest village.

I’d love to hear more about this, if you can share.

How complex / large is it of an installation? How comparable (or not at all) to setting up a large scale wifi network? How complex is the maintenance? Team size for installing / operating vs number of people served?

Everyone’s phone has a custom sim card?

Thanks :) Truly curious about this.

Not OP you replied to, but have done similar before. Answering your questions in order (at least the ones not specific to that scenario) to share some thoughts, which are certainly not answers by any stretch:

- setting up a mobile network is quite different to a WiFi network in some ways, but perhaps a little more in line with a complex large-scale WiFi network. Mobile networks are architected around a "core network" which manages mobility and user traffic, and a "radio access network" which connects the base stations to your core network. The "core" is a fair bit more involved than a large-scale WiFi network setup, at least in my experience. You will need domain knowledge of 3GPP networks, and that's sometimes hard to get hold of, at least outside of traditional mobile operators and vendors. That can be a barrier.

- In terms of maintenance, a well-built RAN should "run itself" for the most-part. You'll want some monitoring on equipment. If you are using modern software-based base stations, they will run on Linux. Treat this like any large at-scale fleet deployment of Linux servers. Keep them patched and plan your maintenance windows for reboots etc. Your core network itself will realistically be a bunch of Linux servers to provide network functions. You'll have the usual periodic maintenance issues keeping up a bunch of complex services that you don't always fully understand, and the temptation to never update anything, as "it's working right now".

- The number of people you need for installing depends on skill sets. You'll need some experienced riggers to install macro sites on masts by climbing the masts. But you also need people who can pour concrete to get masts into the ground. And people who can install masts. You'll need someone who knows some DC electricals and can get everything powered up. You'll need some radio knowledge to plan out the network and check the antennas are pointed in the right directions and with the correct tilts. If you outsource this to a subcontractor, they can probably get the same people who do commercial networks to do it, but that will cost you dearly, and you'll never quite know what happened or how to fix it if something goes wrong!

- To operate the network I guess it's not a huge amount different to any other complex IT system. If you build out your core network well, you can serve a few thousand users without too much trouble, with minimal people. Once you start to scale beyond a few thousand users, you have to scale up the core and architect it a bit better. There's some routine monitoring and maintenance, and the usual things you need to do in any production environment, but in general it's not too horrendous. If you go down the "big vendor box" route like carriers do, they'll take big complex managed services to keep everything in check, but have far fewer really good network people on-staff. The biggest issue you'll have in terms of staffing up to manage it is getting the breadth of knowledge and skills needed to have access to the right range of skills as needed - legacy telecoms can get complex fast. If you are having an issue with IMS for 4G calling (VoLTE), you might only need 1 person, but that's in addition to the 1 3GPP core expert you have, the 1 IP networking expert you have, etc.

- You need to put a custom SIM into every device, and set up a PLMN identity for the network, which is just a 5 or 6 digit number that identifies the network to handsets. The SIM tells the phone what network it should try to join, and contains the crypto keys used to do authentication with the network. You can often get a PLMN allocated by your national telecoms regulator, or use one in the 999/xx range, which are set aside for private, uncoordinated use.

Truly grateful, thanks a lot for all of this insight.

I have recurring daydreams of booting up a fiber ISP or WISP or (thanks to this post) a micro cell network, but peeking at the real-world implementation of those is a good way to remind myself that there's a ton of complexity that I shouldn't underestimate :-) i.e. it helps to keep those dreams "grounded".

I've built temporary 500-people ethernet + wifi networks and I'm always curious to read what it's like to do it at a larger scale. Thanks again!

Don't force your dreams like this to be grounded!

There is complexity in this, but remember here you're talking to people who chose to get deep down into the tech in every component out of a desire to learn, do it themselves, and save money!

What I didn't mention was I built and ran that network effectively by myself (modulo mast climbing), with support of a few others who wanted to learn the ropes.

A fibre ISP is absolutely achievable and there's been a few posts about those on HN recently. Depending on how you go about it, it's absolutely feasible to build out your own fibre GPON network. Heck I know people doing this who have absolutely no background in networking, but have learned the practical skills of splicing and hired in the networking knowledge to support them.

A WISP is a bit simpler to get going than a cellular network, but you can also build one using cellular (that costs more). The big issue WISPs encounter is scaling their business and customer base up - it's easy to do lots of little point to point links in "customer obsessed" mode where you set out infrastructure to reach each rural customer. It's far harder to deliver a great service to these customers, especially as you start to distribute service from these points to multiple customers. A lot of WISPs end up with pretty messy flat networks they can't then scale up, and can't easily augment with fixed fibre to give themselves more capacity.

You absolutely can start your own ISP or WISP. I won't go so far as to say you should, because to evaluate "should" you'd need to understand the local offerings and competitors and regulatory landscape, but it's definitely possible. In the UK, I believe from memory that something like 2 in every 3 kilometres of fibre to the premises has been laid by "non traditional" providers or new entrants, independent of the big telcos.

Your own cellular operator is not impossible, but the scale you need to get to before you have a sellable product is the issue. You need to be (or use) a fibre ISP to get backhaul in. You need to understand site leasing and access arrangements. You'll need to be able to do radio planning and get spectrum access. You'll need billing and customer support and fault resolution. Managed services can help, but you'll rapidly see your revenues drain that way.

In the US there are a number of smaller state-level cellular operators, who effectively do all this themselves. I wouldn't recommend trying to run a mini mobile operator as a business just yet until the supporting ecosystems get better able to serve smaller scale customers though - the rise of private networks will change this, but everyone is still thinking of national scale for now.

Really grateful for your answers and encouragement.

For context, I’m in Canada where the ISP competitive landscape is dire. In the province of Quebec where I am, there are “debates” as to who should manage the government-installed electricity poles and be allowed to run any cable on them.

Actually, it’s the main national telecom giant who ended up managing those poles… Many small towns’ high speed (i.e. dsl) projects are stalled because of this.

I’ll stay on the lookout for an opportunity. :) Thanks

If you are trying to do something about it, get some people together and look at the UK's approach to this - it sounds like you could bring a lot of this to Quebec.

Not saying it would be easy - these sound like deeply entrenched problems to resolve - but often showing precedent for how it's done better elsewhere can help spur Commonwealth governments on.

In the UK, you would want to point them towards the Access to Infrastructure regulations, and the regulator's approach to "duct and pole access" - https://www.ofcom.org.uk/about-ofcom/latest/media/media-rele...

In the UK the "national telecoms giant" has to give equitable wholesale access to ducts and poles, and this is being used to lay fibre to the premises in rural and urban areas.

> I've built temporary 500-people ethernet + wifi networks and I'm always curious to read what it's like to do it at a larger scale.

If you’ve done this, you could do the WISP / private LTE network. Will you likely need to do a lot of research and reading? Yes. Will you occasionally make potentially costly mistakes? Yes. But will you be successful if persistent? Yes!

As someone who owned a small WISP back in the earlier days of the Internet when finding guides was hard to do and has done a private 3G network for fun, it’s definitely doable if you set your mind to it.

Thanks for the encouragement, I really appreciate it.

I’ll do more than encouragement, I’m happy to be an advisor who can offer suggestions/research areas/additional people to talk to as you go through the process. I don’t have the time to be an active participant in your project, but if you email me (contact info in my profile) issues you get stumped on or want a second opinion about into, I’ll always do my best to be helpful.

Just one eNodeB (the "Radio Access Network," i.e. part that connects to the antennas, sourced from Star Solutions), two antennas (13 dBi sectorial antennas with spatial diversity), and an EPC (the "backend," also from Star Solutions) as a VM on a single server. The goal is serve a detector array of 35 indepedent detectors up to 10 km away from the base station (which is mounted on the roof of the tallest building in the research station, some pictures of both a station and the base station that I happened to have taken are available here: https://www.desy.de/news/news_search/index_eng.html?openDire... ). Each station has an omni 8 dBi LTE antenna mounted at several meters height. I also did put a sim card in my phone and it worked fine though that was not the primary purpose (but it allowed me to video call from the middle of the ice sheet far away from the station WiFi, which was kind of a novelty).

The only feasible alternative was 900 MHz WiFi which would have been similar, but lower throughput and much less available technology, whereas LTE modems are cheap and abundant.

It was deployed about a month ago and so far so good. It's data only, and the server the EPC is on just acts as a gateway.

Due to the conditions, the eNB is indoors. Installation of antennas was done by station carpenters as I was not allowed on the roof without training :). I am a physicist, not a telecom engineer but it was not too complicated.

Really fascinating. Thanks a lot for this description!

Did you have to pay for the lisence? Don't these lisence normally cost something in the range of billions of dollars?

No. I suspect if it was in a region people lived in and we weren't using it for research purposes, we may have had to pay, though I doubt it would cost anywhere near that order of magnitude in Greenland...

5G NR allows for 5Ghz to be used as primary carrier in band 46. (as opposed to LTE that only allows it as a secondary carrier.) This wouldn't require a license to use.

I believe CBRS band 48 (3.5Ghz) is lightly licensed but I don't remember if you can set it up as a primary carrier on LTE.

Do you know how does the patent licensing works on 5G NR-U? I have been trying to find an answer but literally everyone in the industry are mum about it.

I really really want to see real world usage of NR-U and as a possible replacement of WiFi.

I understand that NR-U is a full implementation of a 5G base station (and client handset/CPE if you can find one that actually implements NR-U!), and therefore you will require patent licenses for the full implemented stack.

In an ideal world, your radio manufacturer and software vendors would have appropriate patent licenses in place.

For this and other reasons (handset support being commercially problematic since carriers want to preserve their dominance), I don't see NR-U really replacing Wi-Fi. The friction to joining a device to a network is also far higher, and there's much more complexity in running the network and architecting a suitable core network and user plane functions and keeping it all running. WiFi really is a lot simpler in many ways.

Well NR-U is pretty much a Qualcomm technology ( MultiFire ) brought to 3GPP for standardisation. So I expect it to be supported in all 3GPP Rel 16 modem and Qualcomm X60+ modem as well. I dont think Handset support would be a concern unless I am missing something.

I was hoping for some exemption or special arrangement on the patent issues for consumer private 5G Network. WiFI just sucks, comparatively speaking. Including WiFI 6E. And judging from the ways they are doing things I have very little hope for 802.11ay and 802.11be ( WiFi 7 ).

>WiFi Sucks...Including 6E

Outta curiosity, why do you say 6E sucks?

CBRS is very US-specific...

It is indeed an innovative way to give access to spectrum, but it's a pity it has been done in this band (which had a huge potential for usual operators in terms of site reuse).

I suspect in Europe a light licensing approach such as CBRS might be considered in higher bands such as 26 GHz...

At least on paper the Japanese sXGP standard is close to what you want, it’s reportedly just TD-LTE Band 39 and equipments are licensed the same way as Wi-Fi APs and dongles are.

Maybe if there’s enough demand for workplace private phone network, such laws could be passed to run 5G or 4G as Wi-Fi alternatives.

Check out CBRS which is "licensed-by-rule." You should be able to use CBRS to deploy private 5G.

If anyone knows the answers to this for USA I'd be very curious (at this time I don't see one). People are mentioning possibly using a 5ghz band?

Very weird that the ubuntu article talks about how easy it is to do this and makes no mention of spectrum license concerns.

OpenLTE (Wikipedia)

https://en.wikipedia.org/wiki/OpenLTE

OpenLTE (Technical Page, SourceForge)

http://openlte.sourceforge.net/

SourceForge OpenLTE Wiki, installing:

https://sourceforge.net/p/openlte/wiki/Installing%20OpenLTE/

"FPGA Implementation of LTE Downlink Transceiver with Synchronization and Equalization":

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.69...

EETimes, "Implementing LTE on FPGAs":

https://www.eetimes.com/implementing-lte-on-fpgas/#

Also interesting is doing a Google query with "FPGA" and "LTE" and/or "OpenLTE" as the search parameters:

https://www.google.com/search?q=FPGA+and+%28LTE+or+OpenLTE%2...

(Also note that GNU Radio: (https://www.gnuradio.org/about/) and SDR:(https://en.wikipedia.org/wiki/Software-defined_radio) -- are related topics that may contain some overlapping areas of interest...)

And also OpenRAN: “The OpenRAN Project Group is an initiative to define and build 2G, 3G, 4G, and 5G RAN solutions based on general-purpose vendor-neutral hardware, open interfaces and software.”

https://telecominfraproject.com/openran/

Excellent link!

Also, for those that are new to the "RAN" terminology (as I was just a few minutes ago! <g>):

https://en.wikipedia.org/wiki/Radio_access_network

Are these part of WAN's[Wide Area Network]....?

A RAN is mini-WAN?

I would say Yes in terms of size: usually most of RANs are nationwide.

But No in term of type: RAN is a functional part of operator operational network and therefore not as function and traffic neutral as a WAN is.

This is a list of open source tools to do this https://open5g.info/

Something important that may be overlooked in the blog post is that for most bands you need licenses to transmit over the air. ISM bands are unlicensed but may come with other limitations (e.g., in some countries regulators require a listen-before-talk mechanism that is not always implemented in cellular stacks).

All the examples in the blogpost is areas where you own the property, and in most countries can deploy this if you are careful not to interfere with areas outside of your property. With 5G this is easier because you can use ISM bands within the “core” and WiFi closer to the edge.

I'm a little confused about how UE authentication works with open source cellular. Are there re-programmable SIMs that you need to buy? Or it only works with virtual SIM cards written in software on non-commercial equipment.

To ask simply; could I expect to easily connect my iPhone to one of these networks?

Yes, programmable SIM cards.

https://www.smartjac.biz/mobile-telecom/sim-cards/4g-lte-sim...

Buy pre-programmed or invest in a programmer + a bunch of blanks.

Does this work with eSIMs?

This would be super useful if it could me made to work on the secondary eSIM for iDevices.

Unfortunately not - eSim is a fairly closed-shop ecosystem. You can't easily type in the provisioning parameters into a QR code generator and get an eSim to use.

You need to work with a GSMA-approved eSim issuer who has a special CA-signed certificate to authorise a handshake via some cellular standard protocols to do the eSim setup process. This process does prevent keying material being exchanged in plaintext, but also "locks in" the need for an intermediary in the process unfortunately.

So while you could make eSims, you'd need to work with a GSMA-approved issuer.

That's unfortunate. Is it possible bypass this restriction on a rooted Android phone, or is it implemented in hardware?

Afaik, it has little to do with the user-facing software, you need access to the baseband modem part.

As far as I know, eSIMs are usually implemented in physical hardware, close to (or maybe even on) the baseband, but independent from the baseband firmware.

This is because they are considered a trusted execution environment; if they weren't, it would be possible to "clone" eSIM instances.

Ah, right. "Trusted" in the modern dystopian sense that I physically own the thing but it's controlled by someone else.

Exactly. The whole baseband in your phone is considered "trusted" by the network because you can't easily control it. Don't give the carriers ideas - if they thought they could move to a "ma Bell" style of you leasing the phone from them without ever gaining ownership rights of it, someone would try to! Look at carrier locking, and the world of CDMA, where your phone has to have its ESN (serial number) manually whitelisted to join the network... It's a whole different world from general purpose computing!

The mobile standards are built around the assumption that the baseband does as it's told by the network - your phone's transmit slots get scheduled by the base station, and your phone sits quietly until those slots to speak. This extends to the wider architecture and design of the ecosystem - the user is not "meant" to be in charge of their device in the mobile ecosystem. With the split between AP and CP (application processor and cellular processor), if you put the CP on a suitable bus like USB which doesn't give DMA access, you can build a phone you have sufficient control of (see Pinephone etc).

In the world of SIM, this is back to carrier thinking - they control the SIM as it's "theirs". The keys on the SIM are known only to them, not even to you. You're not trusted to know your own SIM authentication parameters. This can be helpful in some ways, as it makes the threat model different to other systems and you can't unwittingly disclose your keys to someone through social engineering... But it's less helpful as customers generally don't think like security architects who designed this, and end up just having their physical SIM stolen, or their carrier ports their number after social engineering...

Where I'm from, phones were always decoupled from carriers. The carrier sells you a SIM card, that's it. It's on you to buy or already have a compatible phone to stick it into. I don't think any of the big carriers ever offered financing as part of the contract the way US ones do. Also we only have prepaid plans.

It's a shame still that you can't have a 100% open-source phone. I'm the kind of person who believes that all of the humanity's knowledge must be freely accessible to everyone. Including schematics and documentation for every device ever made, including ICs. It's counterproductive when multiple companies have to reinvent the same thing... and then keep it secret like the others.

not exactly modern, or dystopian - see also paper money, for instance, which may be owned by you, but is controlled by another entity and contains features making it hard to modify or duplicate.

the analogy is flimsy, i suppose (paper thin, lol?) but the problem is that the user cannot be trusted to be non-malicious. however, with esim technology i had assumed the trust was assured using keys owned by the proivider, so i'm not sure whether there's something else going on here?

Money is only valuable because the society makes it so, and especially because governments only accept taxes in their own currency. But if you own a banknote, it's fully yours. You can spend it on anything — including something illegal like drugs. Or you can draw something on it thus invalidating its value. The government that issued it doesn't have a say in any of this.

But with modern locked-down electronics, you could only do what the manufacturer intends, and nothing more. Continuing with monetary analogies, it's like a credit card that only works for things your bank considers "good" for you.

Sandboxed trusted computing actually offers a way out of this dilemma: Rather than having an entire phone/computer etc. locked down (so that some third party can trust it), there is only a trusted subsystem that can interact with the larger system only in limited and well-defined ways.

Microsoft's plans for the TPM back in the early 2000s have given the entire concept of trusted computing a bad reputation, but besides DRM, there are many legitimate use cases for it that are not anti-consumer/anti-freedom.

Sure. Cloud servers are a good one. But I still see no benefit for the end user to lock down any consumer devices like that. It only benefits the device manufacturers themselves. Like, you know, Apple forcing its online services onto people literally by burning stuff into silicon. I don't have a problem when hardware and software are tightly integrated. I do have a problem when said software isn't modifiable and has a hard dependency on servers you can't control and can't self-host.

Let people modify their modem firmware, just make sure they understand what they're doing. But they might interfere with other people's service, you say? They could as well do that with a $300 SDR, or they could buy a purpose-built cellular jammer. Let governments enforce their laws, don't make something technically impossible because making it possible might enable someone to break a law.

> with esim technology i had assumed the trust was assured using keys owned by the proivider, so i'm not sure whether there's something else going on here?

There is trust both ways:

- You trust the provider's keys so that nobody can later intercept your traffic, as the keys encrypted under it will later be used to encrypt and authenticate that traffic. (Of course the networks themselves have ample security holes and allow for lawful interception, but that's another topic.)

- The provider trusts your eSIM to not expose your keys to the baseband or application processor ever. If it wasn't for that, the provider's invoices might not be defensible in court in case of a billing dispute: You could easily claim that you've been subject to malware that stole your authentication keys and then went on to call toll numbers for hours.

Theoretically, the first point is only addressing your own risk, but it seems like the eSIM designers seem to have taken the position they did (mandatory GSMA PKI signatures). Unfortunately, this also means that "homebrew eSIMs" are out of reach for now.

The latter is very similar to the idea of chip credit and debit cards: The issuer relies in both users and fraudsters not being able to extract and duplicate a card's keys, so that use of these keys can be seen as proof of the authentic card being involved.

Do you know why is this a closed shop? Is there a legal reason or whichever corporation controls it ensured that they have a monopoly? Is there a way to open this up?

From memory, I believe GSMA (the industry association that helps to keep mobile technology dominated by carriers that hold exclusively licensed spectrum, if you're cynical) require everyone who provides eSim to have been security audited. They can then get access to a trusted certificate that will be able to sign the handshake to the embedded security module (eSim).

It's complex, but remember that in the traditional world view of mobile, the carrier "owns" the SIM, and the handset, and the network itself. When the carrier can't control the SIM in its entirety, you need to have someone brokering the relationship here between everyone - otherwise a carrier coming onto a device may lack confidence the device isn't compromised by the previous network that served it.

Some information that might help you start look around the topic - https://pages.arm.com/rs/312-SAX-488/images/GSMA_eSIM_Certif...

eSIM implementations need to be closed because they are considered a secure execution environment for loading eSIM profiles (in that it should not be possible to extract the keys contained in a profile).

I'm not actually sure if there is a good reason for the eSIM profile server (called SM-DP+ in the language of the specs) to be part of the same trusted computing base; maybe defense in depth against a malicious profile/SAT applet trying to access the data of others on the same eSIM?

You don't need hardware for that. Just need to be able to program your own carrier profile... which I guess is very hard to impossible for the average person.

What do you mean by "carrier profile"? An eSIM profile?

I'm not sure about 4G, but certainly with some of the earlier variants it was relatively easy to make your local DIY network visible as 'foreign' roaming network to your phone with it's normal SIM.

How does one go about getting access in the US to use a frequency that can cover a large area per access point?

I've worked in remote mines before which heavily use telemetry and they all seem to be on 2.4 ghz mesh networks. IIRC they need an access point every half a mile or less and are expensive to maintain.

If you could install just one tower in a mine in the office and have the entire area covered, it would be a game changer.

CBRS (3.55-3.7GHz) has been available for over a year now in the US. I’ve worked with a few mines that are deploying it to get a larger coverage area than WiFi. You should start by speaking with one of the SAS vendors, e.g. Federated Wireless.

in case you are interested: In germany (DE) the regulator offers 5G (actually technology neutral) offers local, campus licenses at a very low price: https://www.bundesnetzagentur.de/DE/Sachgebiete/Telekommunik...

1 year, 10MHz, 1km2 residential-> 1300€

Also check out the open source work of Helium and FreedomFi, who are working to help individuals easily deploy 5G/LTE offload for major carriers and get paid for data usage.

https://freedomfi.com/helium5g/

Wow, letting anyone use my network as a back haul in exchange for a cryptocurrency I’ve never heard of.

Sign me up.

Please don't do this. Not only is this a violation of the agreement between you and the ISP, but consumer internet pipes were never designed for this type of service. This is only feasible if the internet coming to your house is a business line, which it won't be if you live in a residential area.

If I pay for unlimited data at XMbps, I expect to be able to use as much data as I want. If I cannot then ISPs should advertise more honestly.

Plus, I'd be very surprised in Comcast Business was actually using separate infrastructure.

Your license probably doesn't have a provision for subletting.

Does screen-sharing and letting someone control your screen count as "subletting"? Does inviting someone to join your local Minecraft game (which internally starts a server and exposes it to the internet) count as subletting?

If your ISP sells you a service of X Mbps (and if they want to be more precise, X packets per second and X total data transferred in a month) you should be able to use it for any purpose you want. The purpose or content of said packet don't suddenly make it take more network resources.

If ISP's networks suddenly can't cope because people start using what they've paid for then it's on them and they need to price it accordingly and market it more honestly.

I'm surprised by how downvoted you are. It is kind of obvious that it is a violation to me here, since we have a history of people reselling their bandwith in blocks of flats.

People feel entitled to their internet access without consideration of infrastructure costs, especially in North America. They see symmetric multi-GB connections commonly offered in countries such as Japan, South Korea and Singapore, and wonder why it can’t be done in the US.

Population density is why: Singapore is ~8400 people per square kilometre, while the US is a scant 36 per square km. That’s two orders of magnitude difference. Everything else follows from this (high prices, single provider, spotty last mile service, etc.)

Population density is often used as an excuse for this, but it's a weak excuse.

Finland has less population density than USA and manages to solve these issues; NYC has more density than Singapore and still has the same problems with internet access and pricing as the less dense areas of USA.

No, it's not about the population density, the key difference is in the lack of competition.

> People feel entitled to their internet access without consideration of infrastructure costs, especially in North America.

What? People are paying the infrastructure costs through their internet bill. If the ISP is pricing it wrong or is mis-representing what they're selling then it's the ISP's fault and not the customers'. The ISP is free to change prices and/or change their marketing to represent the true nature and capability of the service they're selling.

This is true, but even in US locations with high population density, we still don't have symmetric multi gig connections. Instead, we 1 or 2 choices for a wired ISP: generally cable / DOCSIS and DSL. And around here, PSTN copper is literally rotting on the poles, so DSL is out. Fiber is supposed to be installed "soon" (I estimated 1 to 2 years.)

I remember a customer in Italy that in the warehouse didn't have a good enough reception, so he to install a 3G repeater inside to be able to use the phone. After a few weeks, financial police arrived to his place, ordered to shutdown everything and fined him in 5 digits Euro.

I used to work on UMTS networks about a decade back and fresh out of college it was quite daunting. At that time I wanted to study an opensource implementation to gain more understanding but I couldn't find any. Glad to see this in the present time

I have been thinking about how to do a deployment on a farm, using a private 5G network for some sensors and security cameras. I looked at LoraWann but it didn't have the bandwidth for cameras. Would something like this work?

This could get interesting at defcon conferences (if they're still a thing), which is already famous for having the world's most hostile wifi networks. Now DIY, private stingray?

See also RENEW, the “world’s first fully programmable and open-source Massive-MIMO Platform” which may help to provide open source hardware and firmware for high-end installations. https://news.ycombinator.com/item?id=24026416

https://www.ebay.com/itm/FULL-LTE-GSM-Network-IN-A-BOX-NIB-O...

On a related note, the Pine64 folks are working on the PineDio, which will use LoRa https://wiki.pine64.org/wiki/Pinedio

LoRa is incredibly slow at scale due to the shared spectrum and extremely asymmetrical. Also entirely proprietary and patented.

There will also soon be a LoRa addon board (backpanel) for the PinePhone that'll be powered by an ATtiny84! A working port of meshtastic for this device would be very interesting.

https://wiki.pine64.org/images/b/bc/Pinephone_LoRa_BackPanel...

This is not new to 5G. I believe it was HAR2009 that ran its own GSM network. Not sure if it included 3G, but probably not. So use was limited, but still cool that it was possible.

CCC events have ran 2G infra for ages, and since recently there was also 3G and 4G. There were even workshops where you could operate a femtocell.

Can someone educate me as to a/the use case for this?

Does this mean you are providing cell service to others? or is there another purpose for it?

It's a mechanism to use 5G protocols for a localized WAN, not anything to do with phone carriers.

Do you need a different SIM to connect to a private network or you can use a commercial one (Verizon etc..)?

LTE and 5G use something like pre-shared keys for both user and operator so no to the second option in most cases except emergency use (you can make emergency calls via any network).

Interesting. Why don't mesh networking projects switch to this?

"Mobile networks are much more secure than WiFi."

Would like to see this claim substantiated. TLS protocol runs the same on either pipe.

The threat posture of both networks is quite different. As a user, as you rightly point out, TLS means it doesn't matter to you much!

But if you turn it around and thinks about the problem as a business user, where you have some ancient legacy systems that can't do TLS, you can set up a private APN for authorised users, and connect that APN over a VPN or dedicated private leased line to the insecure service. The mobile network itself has a different set of security assumptions that make this possible.

Client isolation by default prevents other devices from probing your device like they can on a wrongly configured wireless LAN.

The authentication keys to join the network cannot be stolen by a compromised phone or phone firmware. An authorized user can't let another unauthorized user access the network using credential sharing. Swapping SIM into another device can be detected and the join attempt rejected.

Long term authentication secrets sit in hardware protected storage in the SIM and core network - radios and base stations never see long term key material. If you join a roaming network, key material remains secure and the roaming network gets scoped keys that only work on their roaming network.

That's not to say any of this is impossible to do with radius and other systems like 802.1x, but it's the default in cellular. As an end user though, TLS is most probably good enough for you, as you say. Put your DNS over TLS and if in doubt use a VPN. A cellular network will offer you much more protection against ARP spoofing by another client device peer, a sensible modern system won't be bothered by this. It's a different threat model and perspective where cellular is more secure - as an individual you might not be too bothered.

That’s an interesting claim though considering mobile network standards have for the longest time had (intentionally) weak crypto and anyone could spoof being a provider (eg stingray). I’m sure wifi has its flaws but “user could potentially misconfigure a network” is different from “this network has one or more intentional back doors but it’s configured correctly other than that”

4G/5G is pretty good on security, compared to 2G :)

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