6 ms·

Can't this be fixed with smarter software in the AP that can: * Dynamically adjust the power level to match the furthest client * Boost the power level on an

Can't this be fixed with smarter software in the AP that can: * Dynamically adjust the power level to match the furthest client * Boost the power level on an interval to check if there are clients further away waiting to connect Additionally, what do mesh Wi-Fi networks do when clients are holding onto a connection? Are they smart enough to know that another node has a stronger signal to the client and trigger a disconnect from the clients' current node so that the it can associate with the stronger node?

josteink 8y ago
I’m no expert on these matters, but WiFi roaming is covered by 802.11r and WiFi-meshes by 802.11s. I assume these specs include mandated behavior in both the APs and the clients.
- admax88q 8y ago
  Traditionally roaming is left to the client device and most implementations are so bad that they won't give up on an old AP so long as they're seeing beacons every year or so. Who cares that I haven't successfully received a packet in the last hour, it's sure better than the 2 second interruption we'll get if we tried to switch. I'm only mildly bitter at the useless roaming behaviour of most clients. Turning transmit power down doesn't really help either. Some clients will roam better but other clients at the edge of the coverage now have no coverage.
  - josteink 8y ago
    Using software on my smartphone I can observe that it changes AP it associates with as I walk around the house where I have a “traditional” 802.11r WiFi network with common wired backend. No new DHCP is triggered either. So it may not be perfect, but it can’t be that bad.
    - jtmarl1n 8y ago
      What do you use to verify which AP your device is connected to? I've not found a convenient way to do this for testing.
      - stupidthrottle 8y ago
        Net Analyzer for iPhone shows the raw BSSID (AP mac) for whatever network you connect to.
      - noselasd 8y ago
        You need to know the MAC address of each of your access points - also known as the BSSID. It should be available in the admin UI of the access point, and sometimes also printed on a label attached to the AP. Knowing that, you need something that shows you details about wifi connections, so you can view the BSSID (MAC address of the AP) you're connected to: Android, iOS: Install the "Network Info II" app Linux: use the iwconfig command Windows: Use the command "netsh wlan show interfaces"
  - Nextgrid 8y ago
    802.11r solves this. I’ve got it configured at my place and roaming is seamless and takes less than 100ms.
    - spac 8y ago
      Can you elaborate on how you configured? What hardware are you using?
      - Nextgrid 8y ago
        I had a few Devolo powerline adapters (which include a WiFi access point) and I reflashed the firmware with OpenWrt as a last resort (the default firmware didn’t support 802.11r and it was hell without it). Works great since then and it saves me from buying a set of enterprise-grade APs.
    - admax88q 8y ago
      802.11r does not fix this. It makes the handoff slightly more efficient but the client still has to decide to actually do the handoff. And that's the part that never seems to happen, as many clients are stupid.
      - Nextgrid 8y ago
        From my testing with iPhones, the stupid behaviour goes away on an 802.11r-enabled network. I noticed the same issues on a legacy network but that all went away after enabling 11r.
        admax88q 8y ago
        I would imagine that I phones has better roaming preference overall. But maybe having 802.11r enabled causes devices to be more optimistic in their roaming as they know they're not switching networks.
- PaulHoule 8y ago
  The Ubiquiti access points and I assume some other brands use the following method to implement roaming: All of the access points broadcast a certain SSID. When a client tries to connect, they coordinate with each other to choose which one will reply to that particular client. That is, the client things it is connected to one AP and doesn't know anything special is happening. If the system wants to move your client to another AP it just disconnects you from the first AP and when you try to reconnect the second AP will reply to you. In a case like that, assignment is driven as much as "having a clear channel" as "having a better connection on the channel". If you had a choice between two channels, once of which was shared and slightly "better" and another you can have to yourself, you are better off having one to yourself. (That way you aren't having to wait for other clients to stop sending or receiving, dealing with interference, etc.) A corollary to that is that if you have both 5GHz and 2.4GHz support on an access point you do best distributing clients between both sides, even if people think 5GHz is better or that 2.4GHz performs better in real life. I am amazed that instead of all the silly gimmicks that APs have been marketed with, nobody has come out with one that has a lot of radios working on different channels and just behaves like a large number of APs. Practically I think this would work way better than channel aggregation.
  - patentatt 8y ago
    Is that how Ubiquiti APs work currently, or is this a description of the now deprecated “fast roaming” thing they were doing a while back? Edit: meant “zero handoff” per replies below.
    - exelius 8y ago
      That type of roaming actually ends up breaking a lot of WiFi implementations — it’s really only super useful for WiFi VoIP phones. I worked with a vendor (Bandspeed) doing that kind of WiFi roaming back in 2005, so it’s not remotely a new concept. Most other devices will jump to another AP broadcasting on the same SSID if the signal is a lot stronger. It’s not nearly as much of an issue as it used to be, but people expect WiFi to Just Work (tm) so it’s better to let the OS’ network stack manage it.
    - 8y ago
zamadatix 8y ago
Technically that power strategy works but in the real world clients don't want to wait a long interval to connect and boosting the power on a short interval creates more RF chaos than you are trying to solve. There are many standards to assist in roaming such as .11k, v, and r. Particularly for mesh nodes s. In the end the strategy used in Wi-Fi is that the end station is the one that decides when to roam and why. Again it comes down to the client knows more information about what it could connect to and when it makes sense for it to roam than the AP could. The AP can just send hints that it'd like it off of it for other clients benefits. Many Enterprise systems come with the ability to tune power the same way they can automatically tune channels. Usually they tune against other APs rather than clients since AP positions and emissions are much more static and controlled by the same system (normally).
jdietrich 8y ago
We can do better than that - beamforming. Better 802.11ac routers use a phased antenna array to change their radiation pattern, steering the RF energy in the desired direction. https://www.oreilly.com/library/view/80211ac-a-survival/9781449357702/ch04.html https://www.oreilly.com/library/view/80211ac-a-survival/9781...
- nerdbaggy 8y ago
  Doesn’t work in high density though
  - shaklee3 8y ago
    It does if your multipath is good enough. Enough antennas on either or both sides help.
- fulafel 8y ago
  Heh, eventually the tech changes enough that the "wifi router" misnomer might become correct.
  - whatshisface 8y ago
    "Wifi router" seems reasonable to me because the box in my living room that does the wifi also routes.
  - zitterbewegung 8y ago
    Then someone builds a new router called a smart router and the cycle repeats itself .
  - jdietrich 8y ago
    With MU-MIMO, it technically changes from a hub to a switch - MU-MIMO prevents spatial collisions, allowing the router to transmit to multiple stations simultaneously. As whatshisface alludes to, a wireless router acts as both an access point and a router.
  - penagwin 8y ago

josteink 8y ago

I’m no expert on these matters, but WiFi roaming is covered by 802.11r and WiFi-meshes by 802.11s. I assume these specs include mandated behavior in both the APs and the clients.

admax88q 8y ago
Traditionally roaming is left to the client device and most implementations are so bad that they won't give up on an old AP so long as they're seeing beacons every year or so. Who cares that I haven't successfully received a packet in the last hour, it's sure better than the 2 second interruption we'll get if we tried to switch. I'm only mildly bitter at the useless roaming behaviour of most clients. Turning transmit power down doesn't really help either. Some clients will roam better but other clients at the edge of the coverage now have no coverage.
- josteink 8y ago
  Using software on my smartphone I can observe that it changes AP it associates with as I walk around the house where I have a “traditional” 802.11r WiFi network with common wired backend. No new DHCP is triggered either. So it may not be perfect, but it can’t be that bad.
  - jtmarl1n 8y ago
    What do you use to verify which AP your device is connected to? I've not found a convenient way to do this for testing.
    - stupidthrottle 8y ago
      Net Analyzer for iPhone shows the raw BSSID (AP mac) for whatever network you connect to.
    - noselasd 8y ago
      You need to know the MAC address of each of your access points - also known as the BSSID. It should be available in the admin UI of the access point, and sometimes also printed on a label attached to the AP. Knowing that, you need something that shows you details about wifi connections, so you can view the BSSID (MAC address of the AP) you're connected to: Android, iOS: Install the "Network Info II" app Linux: use the iwconfig command Windows: Use the command "netsh wlan show interfaces"
- Nextgrid 8y ago
  802.11r solves this. I’ve got it configured at my place and roaming is seamless and takes less than 100ms.
  - spac 8y ago
    Can you elaborate on how you configured? What hardware are you using?
    - Nextgrid 8y ago
      I had a few Devolo powerline adapters (which include a WiFi access point) and I reflashed the firmware with OpenWrt as a last resort (the default firmware didn’t support 802.11r and it was hell without it). Works great since then and it saves me from buying a set of enterprise-grade APs.
  - admax88q 8y ago
    802.11r does not fix this. It makes the handoff slightly more efficient but the client still has to decide to actually do the handoff. And that's the part that never seems to happen, as many clients are stupid.
    - Nextgrid 8y ago
      From my testing with iPhones, the stupid behaviour goes away on an 802.11r-enabled network. I noticed the same issues on a legacy network but that all went away after enabling 11r.
      - admax88q 8y ago
        I would imagine that I phones has better roaming preference overall. But maybe having 802.11r enabled causes devices to be more optimistic in their roaming as they know they're not switching networks.
PaulHoule 8y ago
The Ubiquiti access points and I assume some other brands use the following method to implement roaming: All of the access points broadcast a certain SSID. When a client tries to connect, they coordinate with each other to choose which one will reply to that particular client. That is, the client things it is connected to one AP and doesn't know anything special is happening. If the system wants to move your client to another AP it just disconnects you from the first AP and when you try to reconnect the second AP will reply to you. In a case like that, assignment is driven as much as "having a clear channel" as "having a better connection on the channel". If you had a choice between two channels, once of which was shared and slightly "better" and another you can have to yourself, you are better off having one to yourself. (That way you aren't having to wait for other clients to stop sending or receiving, dealing with interference, etc.) A corollary to that is that if you have both 5GHz and 2.4GHz support on an access point you do best distributing clients between both sides, even if people think 5GHz is better or that 2.4GHz performs better in real life. I am amazed that instead of all the silly gimmicks that APs have been marketed with, nobody has come out with one that has a lot of radios working on different channels and just behaves like a large number of APs. Practically I think this would work way better than channel aggregation.
- patentatt 8y ago
  Is that how Ubiquiti APs work currently, or is this a description of the now deprecated “fast roaming” thing they were doing a while back? Edit: meant “zero handoff” per replies below.
  - exelius 8y ago
    That type of roaming actually ends up breaking a lot of WiFi implementations — it’s really only super useful for WiFi VoIP phones. I worked with a vendor (Bandspeed) doing that kind of WiFi roaming back in 2005, so it’s not remotely a new concept. Most other devices will jump to another AP broadcasting on the same SSID if the signal is a lot stronger. It’s not nearly as much of an issue as it used to be, but people expect WiFi to Just Work (tm) so it’s better to let the OS’ network stack manage it.
  - 8y ago

zamadatix 8y ago

Technically that power strategy works but in the real world clients don't want to wait a long interval to connect and boosting the power on a short interval creates more RF chaos than you are trying to solve. There are many standards to assist in roaming such as .11k, v, and r. Particularly for mesh nodes s. In the end the strategy used in Wi-Fi is that the end station is the one that decides when to roam and why. Again it comes down to the client knows more information about what it could connect to and when it makes sense for it to roam than the AP could. The AP can just send hints that it'd like it off of it for other clients benefits. Many Enterprise systems come with the ability to tune power the same way they can automatically tune channels. Usually they tune against other APs rather than clients since AP positions and emissions are much more static and controlled by the same system (normally).

jdietrich 8y ago

We can do better than that - beamforming. Better 802.11ac routers use a phased antenna array to change their radiation pattern, steering the RF energy in the desired direction. https://www.oreilly.com/library/view/80211ac-a-survival/9781449357702/ch04.html https://www.oreilly.com/library/view/80211ac-a-survival/9781...

nerdbaggy 8y ago
Doesn’t work in high density though
- shaklee3 8y ago
  It does if your multipath is good enough. Enough antennas on either or both sides help.
fulafel 8y ago
Heh, eventually the tech changes enough that the "wifi router" misnomer might become correct.
- whatshisface 8y ago
  "Wifi router" seems reasonable to me because the box in my living room that does the wifi also routes.
- zitterbewegung 8y ago
  Then someone builds a new router called a smart router and the cycle repeats itself .
- jdietrich 8y ago
  With MU-MIMO, it technically changes from a hub to a switch - MU-MIMO prevents spatial collisions, allowing the router to transmit to multiple stations simultaneously. As whatshisface alludes to, a wireless router acts as both an access point and a router.
- penagwin 8y ago