Re: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
Hi Pasi, With quite many Qualcomm based Android devices WCNSS settings have: gNeighborLookupThreshold=76 gNeighborReassocThreshold=81 So having -65dBm instead of -45dBm should be still reasonable. Depends on the chip, antenna, driver... It's really particular to all hw. Myself at 3m, I have a very good signal with a low noise. I need to be at least at 10m to start to get bg scan running. And also, this is only the signal, not the noise (which again depends a lot on the hw) From Julien's experience, -70 is already killing his connectivity experience so such -76 is even more irrelevant in his case. This values can't be set for every hw, there is no way we can generalize. If -65 works in your case, use it. It's not really passive as the device is told to scan every 30secs and bg_simple will go through all channels and not just particular ones like bg_learn. At the chip level a passive scan is a passive scan: there should not be any probes sent. Theoretically, in real life it again depends on hw/drivers... But as said earlier, it depends on hw/drivers and usage context. For instance in the document you linked (ok it's pretty old), it does not care at all about power efficiency, different use case, noise, etc... (note also they are aggressively scanning, it's far from every 30secs) An experiment an all factors would be more relevant. I wanted to get this bg scan configurable in main.conf, mainly for these reasons. Can't remember why it went nacked, but it could be now the perfect occasion to propose such feature again. Though in a perfect world, connman would not have to care at all about this, it should not be his job. Tomasz ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
Re: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
Hi Pasi, How did you evaluated that -65dbm is better than -45dbm? On scanning events amount? -65 is usually already low signal. (relatively to the noise however) Depends on what you are trying to achieve, a better user experience (better connectivity) or better battery life. I bet such background scans are not that power greedy (it's all passive anyway). Though it would require a proper physical measurement to know about that. When you say scanning will block other operations, this is a bit scary: bg_scan in wpa_supplicant handles concurrent scan requests and others properly. It should not block anything really. Tomasz ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
RE: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
How did you evaluated that -65dbm is better than -45dbm? On scanning events amount? -65 is usually already low signal. (relatively to the noise however) 3 meters away from 5GHz access point and my laptop shows -47dBm, with 2.4GHz ap 5m away -54dBm, I really don't want to scan every 30secs. With quite many Qualcomm based Android devices WCNSS settings have: gNeighborLookupThreshold=76 gNeighborReassocThreshold=81 So having -65dBm instead of -45dBm should be still reasonable. Depends on what you are trying to achieve, a better user experience (better connectivity) or better battery life. I bet such background scans are not that power greedy (it's all passive anyway). Though it would require a proper physical measurement to know about that. It's not really passive as the device is told to scan every 30secs and bg_simple will go through all channels and not just particular ones like bg_learn. When you say scanning will block other operations, this is a bit scary: bg_scan in wpa_supplicant handles concurrent scan requests and others properly. It should not block anything really. Scanning itself blocks all other operations as the wlan-chip will need to go through all available channels and it can't handle data transmit/receive during that time. See: QoS-Aware Channel Scanning for IEEE 802.11 Wireless LAN, http://w3.antd.nist.gov/pubs/1569105587.pdf Br, Pasi ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
RE: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
-#define BGSCAN_DEFAULT simple:30:-45:300 +#define BGSCAN_DEFAULT simple:30:-65:300 On which devices has this been tested? Do you know whether the reported threshold is reported equally across these devices? I've several laptops and phones which seem to report the same RSSI levels by running wpa_cli scan wpa_cli scan_result but in the end the wpa_s trusts the data coming from the wlan-driver. To be honest this setting does not affect devices in which the wlan-driver is responsible for roaming as then wpa_s will not do bgscan with those (you will see wpa_s reporting nl80211: Using driver-based roaming then). The main point is that the -45dBm is considered very good RSSI-value and we should not be scanning unnecessarily as scanning will block other operations. Can't say if -65dBm is the _correct_ value but it's better than -45dBm. Br, Pasi ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
Re: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
Hi, On Thu, Jun 12, 2014 at 12:04 PM, Pasi Sjöholm pasi.sjoh...@jolla.com wrote: -#define BGSCAN_DEFAULT simple:30:-45:300 +#define BGSCAN_DEFAULT simple:30:-65:300 On which devices has this been tested? Do you know whether the reported threshold is reported equally across these devices? I've several laptops and phones which seem to report the same RSSI levels by running wpa_cli scan wpa_cli scan_result but in the end the wpa_s trusts the data coming from the wlan-driver. To be honest this setting does not affect devices in which the wlan-driver is responsible for roaming as then wpa_s will not do bgscan with those (you will see wpa_s reporting nl80211: Using driver-based roaming then). The main point is that the -45dBm is considered very good RSSI-value and we should not be scanning unnecessarily as scanning will block other operations. Can't say if -65dBm is the _correct_ value but it's better than -45dBm. Br, Pasi ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
Re: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
Hi, On Thu, Jun 12, 2014 at 12:04 PM, Pasi Sjöholm pasi.sjoh...@jolla.com wrote: -#define BGSCAN_DEFAULT simple:30:-45:300 +#define BGSCAN_DEFAULT simple:30:-65:300 On which devices has this been tested? Do you know whether the reported threshold is reported equally across these devices? I've several laptops and phones which seem to report the same RSSI levels by running wpa_cli scan wpa_cli scan_result but in the end the wpa_s trusts the data coming from the wlan-driver. To be honest this setting does not affect devices in which the wlan-driver is responsible for roaming as then wpa_s will not do bgscan with those (you will see wpa_s reporting nl80211: Using driver-based roaming then). The main point is that the -45dBm is considered very good RSSI-value and we should not be scanning unnecessarily as scanning will block other operations. Can't say if -65dBm is the _correct_ value but it's better than -45dBm. On my devices I'm really happy with -45 dBm (rt2x00usb devices, and ath6kl usb devices). I start to be in trouble at -70dBm, so I also decide to reduce the threshold to -65dBm. https://github.com/aldebaran/connman/commit/278780b2cff48f0a9e9a46d54ffafe384167249e Regards, Julien ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
Re: [PATCH] Change the threshold for background scanning, -45 is actually very good RSSI.
On Wed, 2014-06-11 at 21:40 +, Pasi Sjöholm wrote: Background scanning is done too often per default as RSSI -45 for WLAN is actually very good. Changing it to -65 makes it behave better (same value is used by NetworkManager). Signed-off-by: Pasi Sjöholm pasi.sjoh...@jollamobile.com --- plugins/wifi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/plugins/wifi.c b/plugins/wifi.c index ef4dd95..d867584 100644 --- a/plugins/wifi.c +++ b/plugins/wifi.c @@ -61,7 +61,7 @@ #define INACTIVE_TIMEOUT 12 /* in seconds */ #define FAVORITE_MAXIMUM_RETRIES 2 -#define BGSCAN_DEFAULT simple:30:-45:300 +#define BGSCAN_DEFAULT simple:30:-65:300 #define AUTOSCAN_DEFAULT exponential:3:300 #define P2P_FIND_TIMEOUT 30 On which devices has this been tested? Do you know whether the reported threshold is reported equally across these devices? Cheers, Patrik ___ connman mailing list connman@connman.net https://lists.connman.net/mailman/listinfo/connman
