Build 5G networks using open-source software, general-purpose hardware (2021) | Hacker News Reader

Build 5G networks using open-source software, general-purpose hardware (2021)

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180 pointsteleforce38 comments

Shout out to Fabrice Bellard's Amarisoft, which deploys software defined 5G stations.

[1] https://www.amarisoft.com/ [2] https://bellard.org/lte/

Fabricd Bellard is a rare person who seems to do and understand everything. I often just grab a cup of coffee and read through the code for random projects[0] of his.

[0] https://bellard.org/

Systems Approach has a new book on Private 5G [1], with a hands-on implementation example in the Appendix [2]:

[1] Private 5G: A Systems Approach:

https://5g.systemsapproach.org/

[2] Hands-On Experience Appendix:

https://5g.systemsapproach.org/software/overview.html

There is also a substack: https://systemsapproach.substack.com/

This weeks post covers the same thing as this post - how easy/difficult is it to actually set up a private 5G network compared to a similar WiFi deployment.

Thanks, yes I'm subscribed to the newsletter as well, what a surprise coincident when posting about open 5G on HN and receiving article exactly in the same subject later on the same day.

The direct link for the substack article is here:

https://systemsapproach.substack.com/p/private-5g-as-easy-as...

Currently New York and Dublin are also using open source private 5G networks for their Smart City initiative:

https://connectcentre.ie/news/connect-partners-with-cosmos-i...

Really interested to see if this will get picked up by network operators and how.

In my experience, corporate buying at this level has always been the home turf for salesmen of entrenched companies, partly because they actually pitch better and partly because buying StandardCorpX's product comes with a level of delegating design decisions you could get blamed for to the supplier. That last one typically doesn't come to the same extent with open source.

Not that I'm condoning any of these corporate buying strategies, just stating the fact.

Network operators are the ones driving O-RAN - they have the most to gain: cheaper equipment & more supplier options. However interoperability is not as easy as you might hope, even with an open standard.

>However interoperability is not as easy as you might hope, even with an open standard.

Came here to say this. Rather than being all interoperable / plug and play, you wind up having to validate different combinations of hardware from different vendors... which then has to get revalidated when new versions of software are rolled out.

Do you need a license to deploy this, or can you do it with such low tx power that it's permitted?

Is there anything one can actually do with a home-sized 5G network? As an individual, without being an actual telecom operator and all that.

Campuses like universities could use iot networks in low frequencies which will be much more reliable than Wi-Fi because of range problems.

Use the networks for what?

Maybe I've just been out of school for too long, but I can't think of anything particularly interesting a campus would want an IoT network for beyond maybe motion sensing for automatic light turn-offs and run-of-the-mill security systems.

I can't imagine a low-frequency IoT network being good for broadband access for people walking around (a la wifi) because of bandwidth limitations.

"campus" can mean lots of things... your handle is "vineyardmike" - what about irrigation / water / temperature / other sensors spread over a vineyard?

With lower frequencies comes much lower bandwidth. 5G networks can transmit at much higher power than WiFi, so that's where you get your range at higher frequencie - however that requires licensed spectrum which makes all this a bit harder.

It can be used at small scale like home wifi (small cell / femtocell) and it would probably be on par with regular wifi. Cellular networks don’t really stand out in home-sized few-user deployments though because they’re designed for serving large areas or high user densities.

I’ve set up an LTE network in my house before and while it is a fantastic educational tool, that is pretty much the extent of the benefits offered vs WiFi.

What are the rules for broadcasting though? I thought you get hit with a fine without a lisence if you transmit any sort of radio-frequency

Doesn't 5G share some of the frequencies used by normal wifi? IIRC devices implementing one standard even cooperate with devices implementing the other to coordinate frequency use.

short answer is no, but the frequencies aren't far off

wifi operates at 2.4Ghz most typically and also at 5Ghz (shorter range but faster)

5G will be ranges of frequencies, depending on jurisdictions, but typically between these two frequencies which are the sweet spot for domestic usage

in the US, 5G carries AFAIK have ranges between 2.5Ghz and just under 4Ghz

in the UK we have EE, O2 and Three operating ranges around 700Mhz besides also having ranges around 3.4Ghz and 3.6Ghz were Vodafone operates too, and those work a lot like US 5G

4G in the UK operates under 2.6Ghz, which is pretty close to wifi also, and LTE is just over 850Mhz or so

basically wifi, 4G and 5G are not strictly higher or lower frequency to each other, it depends on local operators

It always amazes me how pulsing some electricity into a wire at a specific frequency can get you arrested lmao. I really don't understand why there's any legislation at all covering anything above 1GHz where there's enough bandwidth for literally everyone to do whatever they damn well want and not enough range to do any damage at all.

There are satellite comm frequencies above 1ghz that you could easily jam from a more powerful terrestrial transmitter, like gps.

Literally my wifi goes down when my microwave turns on... there are reasons regulations are put in place

There is CBRS, which some phones are equipped to use. However, I believe it’s used only in conjunction with licensed bands rather than independently. It’s more of a capacity thing rather than a way to have a carrier using unlicensed spectrum (carriers are quite happy with the license barrier to entry).

The main advantage should be proper base station handoff. If you have a house that can't be covered by a single wifi access point (or an office), then the normal approach is multiple APs with the same SSID. It's a bit of a hack though, you can't guarantee that your device is connected to the one with the best signal, particularly if you move around, and transitioning involves a connection drop.

Proper cellular radio does measurement of signal to surrounding basestations, and seamless handoff. If would have some advantages over wifi in a corporate environment.

This is a bit outdated -- 802.11r fast transitions (FT) allow devices to roam between access points nearly instantly, and 802.11k and v allow access points and clients to exchange scan results, so that access points can move clients to the most appropriate access point.

This does require more than just having multiple access points with the same SSID, and used to be limited to expensive commercial AP brands, but it's quite accessible to consumers these days.

I used to attend O-RAN meetings for a major telecom, and this was always the major hurdle I envisioned for the adoption of these things. On the technical side, it's a fun problem and interesting work, but O-RAN and open source cellular lacks the organic growth other open source projects can enjoy. A comparison point was always the networking space. Open source routers/switches broke into the Juniper/Cisco market, but it doesn't work as well in cellular. Small businesses can buy 1 or 2 open source switches and in aggregate that can start to change the market. No small business is going to own their own spectrum and deploy an open source cell network. And moving to shared spectrum eliminates most of the advantages over WiFi.

I was going to say OFDMA and MUMIMO but wifi 6 got that covered

Has anyone ever seen a software defined radio based phone/client out of interest?

Also I've not properly read the paper yet but it mentions a VCTCXO (Voltage Controlled Temperature Compensated Crystal Oscillator), used with some of the SDRs. A while ago I bought a rubidium clock, which I thought may have been decommissioned from a cell tower. I'm curious how important the clock used is, for a cellular system?

> I'm curious how important the clock used is, for a cellular system

Very, that's why they bother with things like rubidium holdover clocks. A lot of things depend on precise synchronization, both locally and between multiple towers.

Thanks, that makes sense, curious how they seem to get away with a VCTCXO in this case (or at least I couldn't seem to find mention of rubidium clocks in addition).

Different qualities: Quartz crystals are better than Rb when looking at short periods. Long-term stability is normally provided by GPS. Rubidium beats crystals when it comes to stability over hours - it is added as a fallback for when GPS fails. If you don't have a requirement that your system can work lets say 24 or 48 hours without GPS sync, you can skip the Rb.

I too have some kind of GPS-disciplined high accuracy clock (I don’t recall the exact tech but I think rubidium sounds right). From what I recall, precision timing is quite critical on the infrastructure side of things so that the user device can sync to it and accurately transmit and receive in the correct TDD windows.

One of the niftiest things was using the 10MHz reference clock as the clock source for my SDR, and tuning the receiver to the centre carrier of a nearby cell tower. I got a ~0.25Hz beat frequency out of it, which means this cheap eBay clock is accurate to about 1/3.2e9 Hz (cell tower was around 800MHz). Neat!

Yes, for example there is srsue in https://github.com/srsran/srsRAN_4G (the predecessor of the stack used in TFA)

How do you provision devices (eg eSIMs) to run on this network?

using an API to order eSims from an eSim provider like oasis (now tata) and register it in your core network ?

It would be interesting to have some practical application for it. I don't see a point in building such network, unless you can use it for something.

here is one, let me know what you think about it:

Someone to rescue in a mountain, rescue team needs to be sync and rescue machines (drones) to be operated in this hostile area.

Just send a drone to run a dedicated 5g network (like a flying wifi AP) and you gain a 5G data link between humans and machines in minutes.

A tactical bubble.

Probably related, is it possible to create my own eSIM?

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