4 ms·

This article is all about unwrapping the marketing copy and explaining why it sucks. That's still valuable, but I was hoping for a more technical view on it. A

This article is all about unwrapping the marketing copy and explaining why it sucks. That's still valuable, but I was hoping for a more technical view on it. Anyone have an article that explains why the systems are as limited as they are?

mckoss 10y ago
Read more (page 2) - there is a considerable discussion of channel congestion and interference due to over powered zones and large number of devices.
- Filligree 10y ago
  I did. It's still fairly superficial, and not the focus of the article. What I'm looking for is e.g. an explanation of how MIMO works, or why explicit timeslots were considered useful for 802.11n but not 11b.
  - kogepathic 10y ago
    MIMO isn't that complex. It's using multiple antennas to take advantage of multipath propagation. [0] If you want a very simplistic explanation, it's like giving you multiple Ethernet cables to improve throughput. (To gloss over all the details about RF and boil it down to the practical benefit: more bandwidth) Per the article, not everything with MIMO is advertised as 1x1, 2x2, etc. You frequently find WiFi routers mentioning 1T1R (1x1), or 2T2R (2x2). Or maybe just the Chinese routers I look at. This article is mostly on about interference, which is definitely a big issue in populated areas. But there are definitely issues with Linux and the drivers used by AP manufacturers. There's a project: Make Wi-Fi fast [1] which aims to address these issues. They're making good progress, especially in environments with a lot of clients. Just having one 802.11b or g client can really ruin throughput for newer devices due to the timesharing algorithm used by default. [0] https://en.m.wikipedia.org/wiki/MIMO https://en.m.wikipedia.org/wiki/MIMO [1] https://www.bufferbloat.net/projects/make-wifi-fast/wiki/ https://www.bufferbloat.net/projects/make-wifi-fast/wiki/
  - stsp 10y ago
    I would recommend reading books instead of blogs if you really want to understand this stuff. O'Reilly's "802.11n: A Survival Guide" is fairly OK. If you read German, I highly recommend "Wireless LANs" by author Jörg Rech.
hchenji 10y ago
See my comment https://news.ycombinator.com/item?id=13793876 https://news.ycombinator.com/item?id=13793876 . I suggest reading Andrea Goldsmith's or Pramod Vishwanath's book on Wireless Communication. If not, Intro to Communication Systems by Madhow is recommended.
- stsp 10y ago
  These look nice but they focus on the physical layer. Do you happen to know any useful English literature that covers the MAC layer of modern wifi standards (n, ac, ax)? Apart from the 802.11 standards, of course.
  - hchenji 10y ago
    Lectures and video from http://www.cse.wustl.edu/~jain/cse574-16/index.html http://www.cse.wustl.edu/~jain/cse574-16/index.html Book: https://www.pearsonhighered.com/program/Beard-Wireless-Communication-Networks-and-Systems/PGM153625.html https://www.pearsonhighered.com/program/Beard-Wireless-Commu...
    - stsp 10y ago
      Thanks!

mckoss 10y ago

Read more (page 2) - there is a considerable discussion of channel congestion and interference due to over powered zones and large number of devices.

Filligree 10y ago
I did. It's still fairly superficial, and not the focus of the article. What I'm looking for is e.g. an explanation of how MIMO works, or why explicit timeslots were considered useful for 802.11n but not 11b.
- kogepathic 10y ago
  MIMO isn't that complex. It's using multiple antennas to take advantage of multipath propagation. [0] If you want a very simplistic explanation, it's like giving you multiple Ethernet cables to improve throughput. (To gloss over all the details about RF and boil it down to the practical benefit: more bandwidth) Per the article, not everything with MIMO is advertised as 1x1, 2x2, etc. You frequently find WiFi routers mentioning 1T1R (1x1), or 2T2R (2x2). Or maybe just the Chinese routers I look at. This article is mostly on about interference, which is definitely a big issue in populated areas. But there are definitely issues with Linux and the drivers used by AP manufacturers. There's a project: Make Wi-Fi fast [1] which aims to address these issues. They're making good progress, especially in environments with a lot of clients. Just having one 802.11b or g client can really ruin throughput for newer devices due to the timesharing algorithm used by default. [0] https://en.m.wikipedia.org/wiki/MIMO https://en.m.wikipedia.org/wiki/MIMO [1] https://www.bufferbloat.net/projects/make-wifi-fast/wiki/ https://www.bufferbloat.net/projects/make-wifi-fast/wiki/
- stsp 10y ago
  I would recommend reading books instead of blogs if you really want to understand this stuff. O'Reilly's "802.11n: A Survival Guide" is fairly OK. If you read German, I highly recommend "Wireless LANs" by author Jörg Rech.

hchenji 10y ago

See my comment https://news.ycombinator.com/item?id=13793876 https://news.ycombinator.com/item?id=13793876 . I suggest reading Andrea Goldsmith's or Pramod Vishwanath's book on Wireless Communication. If not, Intro to Communication Systems by Madhow is recommended.

stsp 10y ago
These look nice but they focus on the physical layer. Do you happen to know any useful English literature that covers the MAC layer of modern wifi standards (n, ac, ax)? Apart from the 802.11 standards, of course.
- hchenji 10y ago
  Lectures and video from http://www.cse.wustl.edu/~jain/cse574-16/index.html http://www.cse.wustl.edu/~jain/cse574-16/index.html Book: https://www.pearsonhighered.com/program/Beard-Wireless-Communication-Networks-and-Systems/PGM153625.html https://www.pearsonhighered.com/program/Beard-Wireless-Commu...
  - stsp 10y ago
    Thanks!