Comment by userbinator | Hacker News Reader

Comment by userbinator | Hacker News Reader

Parent Full thread

Not if the FCC and other regulatory agencies have anything to say about it...

But telecoms standards are certainly extremely complex; mainly because they are truly designed by very large committees with plenty of bureaucratic process. I did briefly try to read through and comprehend all the 3GPP standards in order to understand the whole system end-to-end --- from the microphone of one mobile to the speaker of another --- but gave up pretty early, and I'd consider myself pretty knowledgeable about the Internet stack from HTML through HTTP, TLS, TCP, and IP, all the way down to the bits on an Ethernet cable or the signals an 802.11b/g transceiver emits.

If you've seen the 802.11 standard, that's about the limit of what I can still understand with a bit of effort. The 3GPP specs are in a similar style of thick standardese, but around 10x denser and more voluminous.

Then again, I don't think it's impossible --- maybe if I had a lot more free time and interest I could. After all, Fabrice Bellard wrote his own 4G base station:

http://bellard.org/lte/

Some people can explain all the details of what happens when someone visits a URL in their browser. Maybe Fabrice can explain all the details of what happens when someone turns on a mobile, associates with a network, and makes a call with it.

As related by others, LTE has a less complicated backhaul network than the 3G networks (My experience is with WCDMA and WiMAX). Part of this is that 3G networks generally consist of several "servers" (in an as abstract sense as possible") and LTE significantly reduces this number.

Another significant factor is that LTE does not do circuit switched data/voice data and is exclusively packet switched and IP based. Of course, Voice over LTE (VoLTE) and IP Multimedia Subsystem (IMS) augments this slightly, but the general case is still true.

And in addition to this: going from microphone to speaker is much more than just the network. Digital coding of voice data, as an example, has been intensively researched and every single bit is squeezed to out to improve network capacity. They do source coding, to model the human voice and then apply to prediction algorithms to further reduce the bit rate. Recently, I heard a figure of 6.7 kb/s for voice data.

A good book, for the introduction on mobile networks almost literally from microphone to the entire network is From GSM to LTE-Advanced: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118861957...

It's been related to me in the past that the 3G/UMTS network stack is famously insanely complex and that the 4G/LTE stack is noticeably less so.

So that might factor into your trouble with 3G and Bellard's success with LTE. :)

3GPP set is easily among the worst standards I've ever read. I often thought that it was deliberately made so, in order lesser companies and individuals would not be able to make their own baseband. Not to mention references to proprietary documents.. I'm very impressed that somebody managed to make a working BS out of this. Still it's strange to choose 3g, 4g is much lighter technology.

re "strange to choose 3g": as some operators even phase out 3G completely, we can expect 3G base stations to be available cheaper than ever. That's only one of the reasons: Osmocom started out from the security analysis perspective; having 3G openly available is a benefit to the general public as well as small business in various ways.

(The opening lines of https://osmocom.org/news/30: "3G is dead, you may think. From the perspective of large scale operators, that may well be the case, but this is precisely the reason why Open Source support for 3G is becoming increasingly interesting: when the focus for earning money shifts towards LTE infrastructure, the threshold for setting up 3G networks is becoming easier to surpass for everyone else.")

3g operates on licensed frequencies (sold for billions in some countries[1]), so you won't be able to setup a functioning network anyway. Maybe in some 3rd world country, in the middle of nowhere or a tiny femtocell..

1. https://en.wikipedia.org/wiki/Spectrum_auction#Germany

True and the German government was very "wise" to auction every last arfcn of their spectrum so no one will attempt to do teaching or R&D in Germany.

But not every country tried that hard, e.g. in the Netherlands one can broadcast with low power (e.g. have your own indoor/campus wide network) or in the US spectrum can be licensed for smaller regions.

Functioning can mean a lot of things. A security researcher trying to downgrade a device from 4G to 3G and then to 2G will be quite happy with a single eNodeB/nodeB/BTS set-up and is glad about low output power. A company to provide coverage on their campus can be quite happy too.

And this is the thing that cheeses me off the most.

Look at the economic activity created around a "junk" wireless band: 2.4GHz. It is junk because of absorption by water molecules, and that's why microwave ovens use it.

Despite how crappy it is, and how much interference it gets, it is so, so useful. WiFi, Bluetooth, and dozens of other protocols. We get so much use out of it.

If some other bands were opened up in the same way for unlicensed use (conforming to a TX power limit of course), we could create more and more applications, especially if it was a bit lower in frequency to allow longer range communication with reasonable power consumption.

But there's no space worldwide for that, because it has all been sold off or otherwise provisioned. It is such a shame.

> Not if the FCC and other regulatory agencies have anything to say about it...

Depends on how much you care about obeying laws. The former generation of hackers was much less intimidated by the law.

Unfortunately, many of them went on to build systems that constitute an actual "permanent record".

Reply on news.ycombinator.com