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Comment by h2odragon | Hacker News Reader

Observer, not participant; but:

It's my understanding that the FCC and equivalents make it almost impossible for there to be open hardware that connects to the phone network. And any cracks they haven't filled, Qualcomm has NDA'd the documentation for.

see https://osmocom.org/projects

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Also there are several other companies that have a lock on that thing.

When I worked at QCOM at one point I had access to that the 3g versions. My boss had printed it out. It was about 2 inches thick single spaced double sided. Rumor was the 4g one was double that. Then there was the 'chipset'/serial interface about the same size.

So could you re-write one? Yeah (given the time for it). Never mind the legal tangle that bcom, qcom, marvel, whatever Motorola is these days, Huawei, ZTE, and others have built around it. That would just be the technical. Then getting it onto a real cell network would take a lot of work. You prob could make your own in a unlicensed band though if you stuck inside the power limits. Title I/II determine what people can and can not do with the US networks. Think the current thinking is physical connection you can do quite a bit, but radio it is locked down. But I could be wrong.

Have to check that proj out. Looks cool!

I'm no expert in this area, so I'm just going to ask: suppose you implement the entire 4G standard, but alter the used frequencies to a range you can legally transmit on (say, the 2.4GHz or 5.2GHz range), would the technology be different enough that it couldn't be adapted into a real 4g modem by changing the frequency range the device operates at? Is there some inherent technical challenge that makes the technology operate around 1600MHz but not around 2400MHz?

LTE has some advantages over WiFi (i.e. the IoT features, the roaming features, the endpoint management features) so I can see a 2.4GHz LTE network being quite useful in some edge cases. With open technology, private LTE networks can probably serve quite nice business use cases.

The particular bands the cell providers run in were sold to them by the government (or bought from someone else who got them from the gov). If I remember correctly it was mostly the antennas lengths and what the tuner was set to for the chipsets (some being fixed, some being more SDR). Some bought those particular bands because they tend to penetrate buildings better than others.

But yeah if you could keep inside the power levels, and stay in the unlicensed bands, and keep out of trouble with the patent courts you probably could make an LTE network. I would not be surprised if many of the chipsets already could do it. Power levels would be your biggest hurdle for something more than a test network.

You might want to take a look at the table on this Wikipedia page showing the frequency bands where LTE has been deployed: https://en.wikipedia.org/wiki/LTE_frequency_bands

It already ranges from 450MHz to 5.2GHz.

No, that is completely possible. I have worked on a project where we ran mostly standard LTE hardware in the ISM band (2.4 G) and it worked fine.

Not only is this possible there is actual spectrum dedicated to this kind of purpose https://en.wikipedia.org/wiki/Citizens_Broadband_Radio_Servi... though there are a lot of other rules around it (e.g. some slices can be allocated in a given region to a licensed user but not all of the slices in a region).

This is not only possible, it's already a thing with unmodified hardware. The 900 MHz band is a ham radio band in the US, but it's used for GSM in Europe. That means that you can quite legitimately set up a GSM base station in the US if you have a ham license, as long as you abide by ham radio regulations (which might require some hacks), e.g. you can't turn on encryption and you need to broadcast your callsign periodically. Then most multiband phones will connect to it thinking it's a European GSM network. I can't find it right now, but I watched a talk where someone described doing just that.

900MHz is also used for LTE in Europe, so I'm pretty sure you could do the same thing with 4G/LTE.

> the FCC and equivalents make it almost impossible for there to be open hardware that connects to the phone network

How?

FCC has issued guidance for manufacturers to protect against modifications that would break FCC rules. The easiest way to do that is to have a closed-source baseband firmware.

https://prplfoundation.org/fcc-open-source-router-software-i...

Sometimes it's easier to ask for forgiveness than permission.

Something tells me you might have a difficult time convincing say Qualcomm with just that reasoning.

You could conceivably reverse-engineer the hardware if you got the support of places like MIT, and then it's fair game from there.

Asking might come with a large fine if 911 service is interrupted.

A fine might actually be lower cost than losing freedom to binary blobs, so there's that.

But most of the time Quallcomm, Broadcom and the others have an army of lawyers and an absurd amount of money to burn to ensure that your project, life and general existence is ruined, just to protect their bottom line.

It depends what you mean by 'closed-source'. Yes it's probably impossible to certify a radio baseband that anyone can hack on. It would be possible to manufacture a radio baseband for which all the source code was public and anyone could verify that that source code was running.

There is no legal requirement to close the baseband off. They tried to close off routers in the same way and got pushback.

Open hardware means that people can be their own manufacturer.

There are lots of places that will make PCBs for you, and sell you the parts to solder together.

The standards themselves are freely available (and extremely difficult to understand) --- just search for 3GPP --- but I think the main problem is spectrum licensing and transmitter approval.

Don't the phone companies have a veto over what they let attach to their networks?

That has to do with IMEI, and with most baseband software, the IMEI can be whatever you want.

Thanks government!

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