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Show HN: End-to-end LTE example with Docker and emulated radio
- md224 8y agoSide question: there's no way to get low-level access to the WiFi adapter in a MacBook Pro, right? It would be nice if I could do SDR stuff with the radio antenna that came with my computer... though I'm guessing it's not the right type of antenna anyway.
- stefan_ 8y agoWiFi adapters are not SDR, lots of the protocol will be implemented in hardware/firmware of the chip.
- tlrobinson 8y agoNot always true: https://www.rtl-sdr.com/nexmon-sdr-turning-a-broadcom-802-11ac-wifi-chip-into-a-tx-capable-software-defined-radio/ https://www.rtl-sdr.com/nexmon-sdr-turning-a-broadcom-802-11... (not sure if it normally uses SDR, probably not, but it does provide low-level access needed for SDR)
- pjc50 8y agoUsually the radio is fixed-band, but the receive and transmit digital side will usually be some combination of fixed-function pipeline and actual DSP software. The problem is that the information needed to reprogram them is highly proprietary.
- cedivad 8y agoYep, you need to be DJI or similar to get access to them. Very discouraging as a small fish. (I've looked into the broadcom-based project above, unfortunately it's not suitable for continuous reception/transmission, and you would still need processing power anyway).
- freedomben 8y agoYes, the wifi antennas are very specifically sized for the 802.11 frequency ranges. They also often have band pass filters built in to prevent transmissions outside of those bands, as required by FCC regulations and such. That said, if you are really interested in that kind of thing, and you are willing to switch to Linux, the wireless card drivers are very hackable. Source: I forked the driver for my wireless card many years ago and still maintain it, tho these days it's mostly the upstream kernel driver plus a few hacks to get the most out of the hardware: https://github.com/FreedomBen/rtl8188ce-linux-driver https://github.com/FreedomBen/rtl8188ce-linux-driver
- tuxxy 8y agoDamn, this is really cool. Great work! Small question: how much does this affect power on the laptops you've used this on?
- freedomben 8y agoThank you! I'm sorry I'm not totally sure what you are asking. Are you asking how much does it drain the laptop battery? To be honest I've never really tested that, but I'm curious now :-) If you are asking how much the driver affects the transmit power of the wireless card, it takes it from 20 dB up to 33 dB, and each 3 dB is a doubling of power, so it cranks it up by a significant amount.
- tuxxy 8y agoYes, I was curious about how much this affects battery drain. It seems like it would be a considerable amount.
- newman8r 8y agonah, and rtl-sdr units are under $20 so you should look into picking one up, they're a blast. You can actually create a transmitter out of a sound card though, it's kind of a fun experiment https://dspillustrations.com/pages/posts/misc/using-your-soundcard-for-hands-on-digital-communication.html https://dspillustrations.com/pages/posts/misc/using-your-sou... Some people have also tried to create a wifi interface from SDR transceivers, but they're extremely inefficient.
- pgorczak 8y agoIf you wonder about real world use cases for open source LTE stacks like srsLTE: They’re great for deploying small ad-hoc cells e.g. in vehicular and rescue scenarios like in our work from earlier this year: https://arxiv.org/abs/1802.09262 https://arxiv.org/abs/1802.09262
- Jhsto 8y agoInteresting research! One question: what would you test given you'd have access to a regulated spectrum?
- pgorczak 8y agoChiming in from GP: I think mobile setups like base stations mounted on drones or high altitude platforms are really interesting. We’re currently looking at providing cellular connectivity to rescuers and rescuees at sea using a fixed wing drone.
- jcims 8y agoWhat do you have to do to get a run of the mill android or iphone to work on a network like this?
- AnonymousRider 8y agoThat is the first question that jumped into mind for me. How is this useful to me now. I assume that the LTE chip in our devices will handshake with these networks seamlessly.
- pgorczak 8y agoThey do and pretty reliably. The devs of the srsLTE stack even have this neat CI setup where they test the codebase against commercial hardware: http://www.softwareradiosystems.com/pipermail/srslte-users/2018-March/001460.html http://www.softwareradiosystems.com/pipermail/srslte-users/2...
- nimbius 8y agothese are interesting PoC's but the biggest hurdle for me is the price of the hardware. ~700-1000 USD for a radio? are there better alternatives anyone knows of?
- Nokinside 8y agoLTE Femtocells (0.1W, 60ft, 6 users) can cost as little as $100. Nokia Flexi Zone can cost <$200 (I think, didn't check) and they have integrated 3G/LTE/Wi-Fi
- pgorczak 8y agoThe https://github.com/srsLTE/srsLTE/ https://github.com/srsLTE/srsLTE/ readme says they’ve tested LimeSDR too (I don’t know how well the smaller versions of Lime would work though)
- bronco21016 8y agoPerhaps I’m missing something but what is the benefit of LTE over 802.11ac? I know that traditionally LTE is only on licensed bands and 802.11ac mostly on unlicensed. However, it seems 802.11ac gear is significantly cheaper. Both technologies can be run across whatever spectrum you’d like. What characteristics does LTE have that makes it better than 802.11ac for some of the applications mentioned?
- person_of_color 8y agoDistance?
- bronco21016 8y agoI thought distance was more tied to effective radiated power, installation, and frequency selections. Off the shelf 2.4 GHz 802.11ac gear can easily do 30+ mi.
- steve19 8y agoWith ultra high gain antennas right? So 30+ miles is only good for point to point applications.
- MuffinFlavored 8y agoIs there a link to a guide somewhere a consumer can follow to increase their off the shelf gear to... anything even close to 30+ mile range?
- gsich 8y agoFor FDD LTE: You have dedicated frequency bands for up and downstream. So full-duplex vs. half-duplex.
- mcbridematt 8y agoMobile/Cell technologies work better when not all stations are "visible" from each other - as the channel access control in 802.11 is fundamentally peer-to-peer (even with an AP) Some of the major outdoor WiFi companies (Ubiquiti, Miktrotik) etc started out with 802.11 then moved to cellular-style (TDMA etc.) methods for this reason.
- pedrocr 8y agoSo a fully open-source phone is now feasible given friendly hardware? I thought replacing the baseband was much farther away.
- pabs3 8y agoThe Osmocom project created a GSM baseband codebase already (but it isn't useful for end-users): https://osmocom.org/projects/baseband/ https://osmocom.org/projects/baseband/ There are LTE modems that run Linux, theoretically the code that runs on them could be rewritten from scratch: https://osmocom.org/projects/quectel-modems/ https://osmocom.org/projects/quectel-modems/ In addition there have been many baseband exploits over the years, those could be used to gain access to basebands and reverse engineer everything.
- peter_retief 8y agoI have started development for low power IOT devices and am very keen to use LTE bands from 450 MHz to 2.7 GHz LTE Cat-M1/NB1/NB2 protocol layers L1-L3 to leverage the low power modems that are being developed on chip. I want to know if there is a way to make a local transmitter, there is no LTE-M cellular spectrum where I work from
- fest 8y agoDoes anyone have experience with private LTE networks and iOS devices? Do they generally work in networks like this?