[HN Gopher] Openwifi: Linux mac80211 compatible full-stack 802.1...
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Openwifi: Linux mac80211 compatible full-stack 802.11/Wi-Fi design
based on SDR
Author : homarp
Score : 233 points
Date : 2020-08-25 17:45 UTC (5 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| newhouseb wrote:
| This relies on OpenOFDM for much of the "Physical" layer of WiFi,
| which has some INCREDIBLE documentation that is really worth
| checking out if you want to understand how modern radios go from
| a radio signal to packets:
|
| https://openofdm.readthedocs.io/en/latest/
|
| (Modern) WiFi shares a lot of similarities to the physical layers
| of LTE/5G NR in their more basic modes, so this is useful well
| beyond WiFi.
| non-entity wrote:
| Wow. I once wondered about building a wifi card with an SDR but
| quickly got discouraged when figuring out how much IEEE charges
| for the specifications.
| pantalaimon wrote:
| All the specifications are on Sci-Hub.
| [deleted]
| djsumdog wrote:
| How does licensing work with software defined Wi-Fi? As I
| understand it, Australia holds many Wi-Fi patents and most of the
| money from radios goes into their University system. Would SDR
| based implementations be in violation of those patents? What if
| someone made a hardware version?
| shakna wrote:
| Some of those patents have expired, so it would take a lot of
| research to be certain. A hardware implementation is likely to
| be patent-infringing.
|
| The SDR implementation is unlikely to be patent-infringing, as
| Australia does not generally allow software patents. [0]
| Software implementations of existing hardware are generally not
| considered to be patent-infringing under the current
| interpretations of law.
|
| However! The SDR implementation is still likely to be
| copyright-infringing, as Australia does have copyright laws
| that are rather vague and far reaching, and Australians are not
| granted the right to give up copyright.
|
| [0] Software patents can be granted, but they require the idea
| "improve the computer" rather than "merely requires generic
| computer implementation". Which is a higher hurdle than people
| expect, and has led to IBM, Microsoft and others losing and
| failing to gain software patents in Australia.
| wmf wrote:
| OpenOFDM looks like Verilog running on an FPGA; is that
| "software"?
| shakna wrote:
| So far as I'm aware, that question has yet to be tested in
| an Australian court.
|
| As Australia operates under rules that translate to
| "reasonable interpretation", rather than strict
| definitions, the answer to your question is "Maybe".
| dayofthedaleks wrote:
| I can't speak to patent encumbrance on anything as recent as
| 802.11ac, but the Australian CSIRO patents began expiring in
| 2013 and have probably all aged out by now.
| beervirus wrote:
| Depends how the patent claims are drafted. But there's no
| reason to think that the software implementation would be
| immune to an allegation of infringement.
| homarp wrote:
| see also https://www.youtube.com/watch?v=Notn9X482LI a talk
| introducing OpenWifi
| tambourine_man wrote:
| 0.2 ms latency.
|
| Pretty good.
| mikenew wrote:
| That's about what I get with my desktop using Cat6 -> Network
| Switch -> Cat6 -> router. That's very impressive.
| antsoul wrote:
| His talk at Fosdem :
| https://fosdem.org/2020/schedule/event/fsr_openwifi/
| Serious_Cheese wrote:
| Please excuse my ignorance,I'm fairly new to this field. So with
| OpenWifi, will I have control as to what packets I would like to
| send over the air? So for example, can I construct a specific
| packet using OpenWifi and then send them over the air over a
| specific channel (say channel 11, 2.4 Ghz)?
| alex7o wrote:
| Not exactly, you can already do this using monitoring mode on
| your normal WiFi card. This is using SDR(software defined
| radio) to create a WiFi card from scratch. Technical speaking
| you can recreate any radio signal using SDR, with some
| limitations of course.
| etaioinshrdlu wrote:
| It seems one of the final missing links to fully open source
| hardware WiFi would be the RF transceiver chip. This is, to my
| understanding, something similar to a high-bandwidth DAC and ADC
| coupled with configurable frequency mixers to access radio
| frequencies.
|
| Is anyone trying to create an open source version of that chip? I
| understand there's not a lot in the way of open source analog
| chip designs out there, but with Google/Skywater's free PDK, the
| time may be ripe to change that.
|
| Also, there are many SDR LTE base stations, but can we make our
| own SDR LTE handset as well? Can it connect to an existing cell
| network?
| myself248 wrote:
| How open does it need to be?
|
| If you're willing to take up a suitcase worth of room, you can
| use standard analog ICs and RF building blocks to take a quite
| normal DAC and upconvert it to RF, and downconvert the receive
| chain likewise to a very common ADC. The standard wifi channel
| width of 20MHz should place it within reach of quite a few off-
| the-shelf chips.
|
| That approach should be able to do the whole thing with no NDAs
| or whatever; it would be a fine capstone project for someone
| chasing an EE/RF degree...
| etaioinshrdlu wrote:
| I think it would be cool if 100% of the digital logic was
| open source, and 100% of the analog was at least well-
| understood, and commoditized. Kind of like how you don't need
| an open source op-amp, they're well understood and
| commoditized (for most applications).
|
| Does it really take up a suitcase worth of electronics to do
| what the transceiver IC's are doing?
| myself248 wrote:
| Probably not, but it's a tradeoff between integration and
| modularity/testability. Take a look at slide 23: https://nt
| ms.org/files/Jan2018/Microwave_Radio_Cowtown_2018....
|
| Can you build that all onto one board? Yeah sure, after
| it's proven and set in stone.
| sasaf5 wrote:
| > can we make our own SDR LTE handset
|
| To achieve the same data rates as a usual LTE handset, but
| using SDR instead of an ASIC, would make it extremely power
| hungry. Power is not much of an issue for the base station, but
| for the handset it is essential.
| jacquesm wrote:
| Isn't that a patent minefield?
| mschuster91 wrote:
| If one is selling it yes indeed. For merely publishing the
| source? I'm not sure.
| floatingatoll wrote:
| "Is anyone being funded to create an open source version of
| that chip?" might be a more pragmatic question.
| monocasa wrote:
| The Google/Skywater PDK only allows for digital designs at the
| moment.
| etaioinshrdlu wrote:
| There is definite progress in bringing analog support, but I
| agree it is nowhere near ready yet.
| teleforce wrote:
| I'd say it is very unlikely and close to impossible unless it's
| sponsored by a government fund or a very big IC design company
| that's as big as Intel. But I'm glad if someone can proof me
| wrong :-)
|
| Nowadays if you want an RF transceiver chip you either go with
| direct synthesis of ADC/DAC or homodyne architecture. The
| companies that have both of these design capabilities are ADI
| and TI, and both them are happy with their monopoly.
|
| But if any R&D company that probably can pull it off it will be
| IMEC, and coincidentally it is the employer of some of Openwifi
| engineers. FYI, IMEC are both funded by Belgium government and
| a well established IC design company.
| bri3d wrote:
| If you're going down to the "fixed function chips must also be
| open" realm, you'd also need an open source FPGA (or to use PDK
| to try to tape out) for the OpenWifi design. My read is that
| currently OpenWifi is also tied to proprietary Xilinx IP cores
| like the Xilinx Viterbi Decoder.
| [deleted]
| etaioinshrdlu wrote:
| Yes, I agree. But perhaps the design that is implemented on
| the FGPA could just be turned into a regular ASIC as well,
| once it is known to work well.
| Lramseyer wrote:
| The challenge of doing that, is that there are apparently a
| lot of proprietary IP blocks (both analog and digital) that
| are in the FPGA (like the Viterbi decoder as the parent
| comment suggests) that would need to be redesigned before
| you could tape it out into your own chip.
|
| I am not sure what other IP blocks are being used in these
| FPGAs, but a viterbi decoder can be pretty area and power
| heavy (relatively speaking.) I'm not sure if you would be
| able to get enough performance [speed] with modern WiFi
| protocols by implementing it in normal FPGA fabric hence
| why those blocks are woven into the FPGA.
|
| All that said, this is still a very good thing, because it
| marks a step forward towards a more open source hardware
| ecosystem.
| [deleted]
| bb88 wrote:
| Question: How does the AGPLv3 work when it's
| describing/programming hardware? I have a good idea how it works
| on software, but less than a good idea on hardware.
| linuxlizard wrote:
| Is the paper available elsewhere?
| https://biblio.ugent.be/publication/8663043/file/8663044.pdf
| homarp wrote:
| try https://www.orca-project.eu/wp-
| content/uploads/sites/4/2020/...
| linuxlizard wrote:
| Works. Thank you!
| [deleted]
| jhallenworld wrote:
| This project (and OpenOFDM) is massively impressive. The standard
| is complex, and almost nothing works until just about everything
| is working. They should write a blog about when the first ping
| worked.
|
| Anyway, there is a lot of value as a testbench or as a standard
| implementation for others. I can only imagine how much a
| testbench would cost...
|
| https://ip.cadence.com/uploads/706/dsv-sim-eth-wireless80211...
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(page generated 2020-08-25 23:00 UTC)