4 ms·

LoRa Backscatter [pdf]

135 points by feelthepain 9y ago

NZSmartie 9y ago
Got a mirror? Website imposes a article viewing limit...
- hueving 9y ago
  Open in incognito
- rene_obolensky 9y ago
  https://pastebin.com/WXHrdxmF https://pastebin.com/WXHrdxmF
- stickfigure 9y ago
  Disable Javascript for that site and it reads normally. I've found that most news sites become much more readable (and chew through far less of my CPU, and stop autoplaying loud videos, and skip paywalls) with JS disabled. The Chrome plugin I'm using (Quick Javascript Switcher) disables on a per-domain basis and remembers the setting for each. I'm a huge fan of SPAs and JS in the browser and yet I'm quickly blocking JS out of large swaths of the internet simply because it improves the browsing experience. I'm not quite sure what this lesson is teaching me.
  - baccredited 9y ago
    YesScript worked for me on Firefox. Thanks for the idea. https://addons.mozilla.org/en-US/firefox/addon/yesscript/developers https://addons.mozilla.org/en-US/firefox/addon/yesscript/dev...
    - sohkamyung 9y ago
      Just a note that YesScript isn't compatible with my Firefox Nightly now (due to the move to WebExtensions) and will probably stop working with Firefox in general in the future.
- jacknews 9y ago
  "Got a mirror?" Ha! I thought you were going to propose a visible-spectrum variant of this tech.
- endorphone 9y ago
  http://www.economist.com/node/21728866/amp http://www.economist.com/node/21728866/amp
- StavrosK 9y ago
  https://www.eternum.io/ipfs/Qmbjup8RZsg9X6w6frmLY74utsjqQgQXkn2ikp4YpZk5Dy/ https://www.eternum.io/ipfs/Qmbjup8RZsg9X6w6frmLY74utsjqQgQX...
dsun180 9y ago
This website is so brokenly slow. The initial load does 184 xhr-requests mostly in series, oh my god where does this end?
- StavrosK 9y ago
  They're just cleverly preparing you for the experience of the first website served over LoRa.
wonderous 9y ago
Anyone know of any notable related research on real world use of this tech? Best I was able to find was "An Investigation of Fading on a Short Range 900MHz radio link": https://mentor.ieee.org/802.11/dcn/10/11-10-1355-00-00ah-fading-on-short-range-900-mhz.pdf https://mentor.ieee.org/802.11/dcn/10/11-10-1355-00-00ah-fad...
- junkcollector 9y ago
  You might have more luck looking at Active RFID. The same technology in any meaningful sense.
anfractuosity 9y ago
It says regarding CSS "That makes even faint LoRa signals easy to distinguish from background noise, which fluctuates randomly". Is CSS better than FSK than in this respect or..? Edit: http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20TI%20NarrowBand%20vs%20LORA.pdf http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20... Says "Spreading codes does not improve sensitivity over FSK systems, for usable datarates you get similar sensitivity using standard FSK modulation"
- junkcollector 9y ago
  CSS is an analog (continuous frequency function) modulation where the CSS standard specifies that only linear encoding be used while FSK is a digital modulation that can employ pseudo-random keying and operates at discrete frequency keys. Without these restriction imposed by standards, FSK would be a special case of CSS, at least mathematically.
- ac29 9y ago
  >background noise, which fluctuates randomly From years of experience selling, supporting, and installing 900MHz ISM radios, I can tell you this is not the case in many, many places (it describes a greenfield application more or less correctly, though). 900MHz is heavily used in the US and describing the noise as "background" or "random" is disingenuous at best. I'd like to see someone install a LoRa hub on a tower with several other 900MHz radios (common) and see how well it works.
  - anfractuosity 9y ago
    That's very interesting cheers. Just to clarify that quote was from the article this post originally linked to, rather than the paper it now links to.
j_s 9y ago
LoRaWAN packet received at record distance of 702 km | https://news.ycombinator.com/item?id=15201692 https://news.ycombinator.com/item?id=15201692 | (5 days ago, 178 points, 50 comments) > animats: Wow. Both the receiving and transmitting antennas were omnidirectional > vvanders: I regularly see APRS packets of 120mi+, although probably at a lot more power. > superkuh: I run two ubiquiti nanostation M900 at home on a 10m pole and in my car through the sunroof for a mobile data link. > aw3c2: From a balloon in almost 40km altitude.
inanutshellus 9y ago
"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." —Tanenbaum, Andrew S. (1989).
- StavrosK 9y ago
  Yeah but latency sucks.
- vanderZwan 9y ago
  A more up-to-date take on this: > Games on Disc More Energy Efficient than Downloads http://www.notechmagazine.com/2014/09/games-on-disc-more-energy-efficient-than-downloads.html http://www.notechmagazine.com/2014/09/games-on-disc-more-ene... And if you really want to dive into the complications of this topic from a broader perspective of energy use, this piece is full of thought-provoking questions, even if you don't necessarily agree with the conclusions: http://www.lowtechmagazine.com/2015/10/can-the-internet-run-on-renewable-energy.html http://www.lowtechmagazine.com/2015/10/can-the-internet-run-...
Iv 9y ago
It would be nicer if it were not proprietary.
miekw 9y ago
Here's the paper: https://homes.cs.washington.edu/~gshyam/Papers/loRaBackscatter.pdf https://homes.cs.washington.edu/~gshyam/Papers/loRaBackscatt... Tech like this already exists (look up "UHF RFID") and the picture they've got looks very similar to existing tags (image search for "alien rfid tag"). The interesting thing here is managing to implement LoRa's modulation scheme in a passive tag.
- junkcollector 9y ago
  It's not a passive tag. If you only read 3 sentences into the abstract, you find out that it is an active device. This is repeated at the end of the abstract and right at the beginning of page 2 in the introduction.
donohoe 9y ago
I worry about encryption of sensitive data. I don't doubt it can be done, but can their "twenty-cent" chip handle it without messing up its lightweight low-power nature?
- junkcollector 9y ago
  Modern microcontrollers can be had in the sub-$5 range that support hardware implemented encrypting algorithms. Mostly it's a worthless feature but we aren't far out from it being more or less standard even in the $0.20 guys. The bigger issue is that the entire point of this system is to remove cost of deployment and maintenance for cheap highly distributed lo-fi systems. The cost of keying all those devices for encryption would defeat the purpose. Also the added data overhead of the encryption would possibly exceed the amount of actual data you are trying to get out of the system. Also, why do you even want to encrypt it in the first place?
  - pjc50 9y ago
    The Economist article for the same subject suggested using this in medical devices. One-time keying may not be as expensive as you think, a simple matter of IC fuses, but you're right that key management and "enrolment" generally for these tiny things will be a pain.
    - junkcollector 9y ago
      Medical is just an example of the economist not understanding the product vs the buzzline. It is a terrible tech implementation for medical, but I agree that you generally want medical encrypted. However, if you are talking medical, the cost of the sensor device is tiny compared to other costs even for very expensive sensors. Fuse based programming would have a whole host of issues. You either need a destructive fill device or load at the factory. If you load at the factory you have to trust them to not retain copies, keeping in mind that it will probably me manufactured in China. If you use a fill device you open up for destructive programming (IC fuses) you open up a bunch of liability for accidental damage to the device plus the cost of a technician plus training can quickly swamp out the cost of your low cost sensor network. Finally, these sorts of networks work best with asynchronous uni-diretional communication applications. This makes good crypto-practices very difficult. If you chose full crypto and handshake protocols, the amount of data you spend just exchanging keys and handshakes will exceed the data the sensors collect.
asteinbr 9y ago
Which font is used in the document?
- isp 9y ago
  Linux Libertine: https://en.wikipedia.org/wiki/Linux_Libertine https://en.wikipedia.org/wiki/Linux_Libertine $ pdffonts loRaBackscatter.pdf name type emb sub uni object ID ------------------------------------ ----------------- --- --- --- --------- OZJJTN+LinBiolinumTB Type 1 yes yes yes 116 0 LWEMPN+LinBiolinumT Type 1 yes yes yes 118 0 LWEMPN+LinBiolinumT Type 1 yes yes yes 119 0 LILBVD+LinLibertineT Type 1 yes yes yes 120 0 LILBVD+LinLibertineT Type 1 yes yes yes 121 0 ...
limpkin 9y ago
"So, we reverse-engineer the LoRa physical layer using the patents filed by Semtech [27, 57], which is the key LoRa chipset manufacturer. We also use the Semtech 1276 starter kit [10] that provides an interface to transmit LoRa packets with various bitrates and an arbitrary payload. Finally, we analyze the transmissions from the LoRa chipsets on a USRP." This is some impressive work.
- Nelkins 9y ago
  There has been some prior work on this: - Decoding LoRa: Realizing a Modern LPWAN with SDR [1] - Presentation on this work from GRCon16 [2] - Slides from the above presentation [3] [1] https://pubs.gnuradio.org/index.php/grcon/article/download/8/7/ https://pubs.gnuradio.org/index.php/grcon/article/download/8... [2] https://www.youtube.com/watch?v=-YNMRZC6v1s https://www.youtube.com/watch?v=-YNMRZC6v1s [3] https://static1.squarespace.com/static/54cecce7e4b054df1848b5f9/t/57489e6e07eaa0105215dc6c/1464376943218/Reversing-Lora-Knight.pdf https://static1.squarespace.com/static/54cecce7e4b054df1848b...
rakshaaas 9y ago
This paper to be presented in ACM SenSys in November actually demonstrates ability to backscatter to distances as high as 3.4 kilometers at 70 microwatts using narrow band FSK transmissions. http://www.ambuj.se/LoRea-CR.pdf http://www.ambuj.se/LoRea-CR.pdf LoRa while achieves impressive sensitivity levels, this is for very low bitrates of tens of bps. For any practical data rate the sensitivity levels are similar to FSK.

135 points by feelthepain 9y ago

NZSmartie 9y ago

Got a mirror? Website imposes a article viewing limit...

hueving 9y ago
Open in incognito
rene_obolensky 9y ago
https://pastebin.com/WXHrdxmF https://pastebin.com/WXHrdxmF
stickfigure 9y ago
Disable Javascript for that site and it reads normally. I've found that most news sites become much more readable (and chew through far less of my CPU, and stop autoplaying loud videos, and skip paywalls) with JS disabled. The Chrome plugin I'm using (Quick Javascript Switcher) disables on a per-domain basis and remembers the setting for each. I'm a huge fan of SPAs and JS in the browser and yet I'm quickly blocking JS out of large swaths of the internet simply because it improves the browsing experience. I'm not quite sure what this lesson is teaching me.
- baccredited 9y ago
  YesScript worked for me on Firefox. Thanks for the idea. https://addons.mozilla.org/en-US/firefox/addon/yesscript/developers https://addons.mozilla.org/en-US/firefox/addon/yesscript/dev...
  - sohkamyung 9y ago
    Just a note that YesScript isn't compatible with my Firefox Nightly now (due to the move to WebExtensions) and will probably stop working with Firefox in general in the future.
jacknews 9y ago
"Got a mirror?" Ha! I thought you were going to propose a visible-spectrum variant of this tech.
endorphone 9y ago
http://www.economist.com/node/21728866/amp http://www.economist.com/node/21728866/amp
StavrosK 9y ago
https://www.eternum.io/ipfs/Qmbjup8RZsg9X6w6frmLY74utsjqQgQXkn2ikp4YpZk5Dy/ https://www.eternum.io/ipfs/Qmbjup8RZsg9X6w6frmLY74utsjqQgQX...

dsun180 9y ago

This website is so brokenly slow. The initial load does 184 xhr-requests mostly in series, oh my god where does this end?

StavrosK 9y ago
They're just cleverly preparing you for the experience of the first website served over LoRa.

wonderous 9y ago

Anyone know of any notable related research on real world use of this tech? Best I was able to find was "An Investigation of Fading on a Short Range 900MHz radio link": https://mentor.ieee.org/802.11/dcn/10/11-10-1355-00-00ah-fading-on-short-range-900-mhz.pdf https://mentor.ieee.org/802.11/dcn/10/11-10-1355-00-00ah-fad...

junkcollector 9y ago
You might have more luck looking at Active RFID. The same technology in any meaningful sense.

anfractuosity 9y ago

It says regarding CSS "That makes even faint LoRa signals easy to distinguish from background noise, which fluctuates randomly". Is CSS better than FSK than in this respect or..? Edit: http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20TI%20NarrowBand%20vs%20LORA.pdf http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20... Says "Spreading codes does not improve sensitivity over FSK systems, for usable datarates you get similar sensitivity using standard FSK modulation"

junkcollector 9y ago
CSS is an analog (continuous frequency function) modulation where the CSS standard specifies that only linear encoding be used while FSK is a digital modulation that can employ pseudo-random keying and operates at discrete frequency keys. Without these restriction imposed by standards, FSK would be a special case of CSS, at least mathematically.
ac29 9y ago
>background noise, which fluctuates randomly From years of experience selling, supporting, and installing 900MHz ISM radios, I can tell you this is not the case in many, many places (it describes a greenfield application more or less correctly, though). 900MHz is heavily used in the US and describing the noise as "background" or "random" is disingenuous at best. I'd like to see someone install a LoRa hub on a tower with several other 900MHz radios (common) and see how well it works.
- anfractuosity 9y ago
  That's very interesting cheers. Just to clarify that quote was from the article this post originally linked to, rather than the paper it now links to.

j_s 9y ago

LoRaWAN packet received at record distance of 702 km | https://news.ycombinator.com/item?id=15201692 https://news.ycombinator.com/item?id=15201692 | (5 days ago, 178 points, 50 comments) > animats: Wow. Both the receiving and transmitting antennas were omnidirectional > vvanders: I regularly see APRS packets of 120mi+, although probably at a lot more power. > superkuh: I run two ubiquiti nanostation M900 at home on a 10m pole and in my car through the sunroof for a mobile data link. > aw3c2: From a balloon in almost 40km altitude.

inanutshellus 9y ago

"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." —Tanenbaum, Andrew S. (1989).

StavrosK 9y ago
Yeah but latency sucks.
vanderZwan 9y ago
A more up-to-date take on this: > Games on Disc More Energy Efficient than Downloads http://www.notechmagazine.com/2014/09/games-on-disc-more-energy-efficient-than-downloads.html http://www.notechmagazine.com/2014/09/games-on-disc-more-ene... And if you really want to dive into the complications of this topic from a broader perspective of energy use, this piece is full of thought-provoking questions, even if you don't necessarily agree with the conclusions: http://www.lowtechmagazine.com/2015/10/can-the-internet-run-on-renewable-energy.html http://www.lowtechmagazine.com/2015/10/can-the-internet-run-...

Iv 9y ago

It would be nicer if it were not proprietary.

miekw 9y ago

Here's the paper: https://homes.cs.washington.edu/~gshyam/Papers/loRaBackscatter.pdf https://homes.cs.washington.edu/~gshyam/Papers/loRaBackscatt... Tech like this already exists (look up "UHF RFID") and the picture they've got looks very similar to existing tags (image search for "alien rfid tag"). The interesting thing here is managing to implement LoRa's modulation scheme in a passive tag.

junkcollector 9y ago
It's not a passive tag. If you only read 3 sentences into the abstract, you find out that it is an active device. This is repeated at the end of the abstract and right at the beginning of page 2 in the introduction.

donohoe 9y ago

I worry about encryption of sensitive data. I don't doubt it can be done, but can their "twenty-cent" chip handle it without messing up its lightweight low-power nature?

junkcollector 9y ago
Modern microcontrollers can be had in the sub-$5 range that support hardware implemented encrypting algorithms. Mostly it's a worthless feature but we aren't far out from it being more or less standard even in the $0.20 guys. The bigger issue is that the entire point of this system is to remove cost of deployment and maintenance for cheap highly distributed lo-fi systems. The cost of keying all those devices for encryption would defeat the purpose. Also the added data overhead of the encryption would possibly exceed the amount of actual data you are trying to get out of the system. Also, why do you even want to encrypt it in the first place?
- pjc50 9y ago
  The Economist article for the same subject suggested using this in medical devices. One-time keying may not be as expensive as you think, a simple matter of IC fuses, but you're right that key management and "enrolment" generally for these tiny things will be a pain.
  - junkcollector 9y ago
    Medical is just an example of the economist not understanding the product vs the buzzline. It is a terrible tech implementation for medical, but I agree that you generally want medical encrypted. However, if you are talking medical, the cost of the sensor device is tiny compared to other costs even for very expensive sensors. Fuse based programming would have a whole host of issues. You either need a destructive fill device or load at the factory. If you load at the factory you have to trust them to not retain copies, keeping in mind that it will probably me manufactured in China. If you use a fill device you open up for destructive programming (IC fuses) you open up a bunch of liability for accidental damage to the device plus the cost of a technician plus training can quickly swamp out the cost of your low cost sensor network. Finally, these sorts of networks work best with asynchronous uni-diretional communication applications. This makes good crypto-practices very difficult. If you chose full crypto and handshake protocols, the amount of data you spend just exchanging keys and handshakes will exceed the data the sensors collect.

asteinbr 9y ago

Which font is used in the document?

isp 9y ago
Linux Libertine: https://en.wikipedia.org/wiki/Linux_Libertine https://en.wikipedia.org/wiki/Linux_Libertine $ pdffonts loRaBackscatter.pdf name type emb sub uni object ID ------------------------------------ ----------------- --- --- --- --------- OZJJTN+LinBiolinumTB Type 1 yes yes yes 116 0 LWEMPN+LinBiolinumT Type 1 yes yes yes 118 0 LWEMPN+LinBiolinumT Type 1 yes yes yes 119 0 LILBVD+LinLibertineT Type 1 yes yes yes 120 0 LILBVD+LinLibertineT Type 1 yes yes yes 121 0 ...

limpkin 9y ago

"So, we reverse-engineer the LoRa physical layer using the patents filed by Semtech [27, 57], which is the key LoRa chipset manufacturer. We also use the Semtech 1276 starter kit [10] that provides an interface to transmit LoRa packets with various bitrates and an arbitrary payload. Finally, we analyze the transmissions from the LoRa chipsets on a USRP." This is some impressive work.

Nelkins 9y ago
There has been some prior work on this: - Decoding LoRa: Realizing a Modern LPWAN with SDR [1] - Presentation on this work from GRCon16 [2] - Slides from the above presentation [3] [1] https://pubs.gnuradio.org/index.php/grcon/article/download/8/7/ https://pubs.gnuradio.org/index.php/grcon/article/download/8... [2] https://www.youtube.com/watch?v=-YNMRZC6v1s https://www.youtube.com/watch?v=-YNMRZC6v1s [3] https://static1.squarespace.com/static/54cecce7e4b054df1848b5f9/t/57489e6e07eaa0105215dc6c/1464376943218/Reversing-Lora-Knight.pdf https://static1.squarespace.com/static/54cecce7e4b054df1848b...

rakshaaas 9y ago

This paper to be presented in ACM SenSys in November actually demonstrates ability to backscatter to distances as high as 3.4 kilometers at 70 microwatts using narrow band FSK transmissions. http://www.ambuj.se/LoRea-CR.pdf http://www.ambuj.se/LoRea-CR.pdf LoRa while achieves impressive sensitivity levels, this is for very low bitrates of tens of bps. For any practical data rate the sensitivity levels are similar to FSK.