Does it worth to have different value for 5GHz?
On Mon, Jan 17, 2011 at 13:32, <juuso.oikarinen@xxxxxxxxx> wrote:
> From: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx>
>
> The passive scan channel dwell time currently used is 30ms-60ms. A typical
> beacon interval for AP's is 100ms. This leads to a ~30% worst-case probability
> of finding an AP via passive scanning.
>
> For 5GHz bands for DFS frequencies passive scanning is the only scanning
> option. Hence for these, the probability of finding an AP is very low.
>
> To fix this, increase the passive channel scan dwell times (also the early
> leave value, as 5GHz channels are still typically very silent.) Use a value
> of 100ms, because that covers most typical AP configurations.
>
> Based on testing the probability of finding an AP (102.4ms beacon interval) on
> a single scan round are as follows (based on 100 iterations):
>
> dwell min/max (ms) Â | probability
> ---------------------+------------
> 30/60 Â Â Â Â Â Â Â Â| 35%
> 60/60 Â Â Â Â Â Â Â Â| 56%
> 80/80 Â Â Â Â Â Â Â Â| 77%
> 100/100 Â Â Â Â Â Â Â| 100%
>
> Total scan times now and after the change:
>
> Region | Before (s) | After (s)
> -------+------------+----------
> 00 Â Â | 0.77 Â Â Â | 1.48
> FI Â Â | 0.95 Â Â Â | 2.01
> US Â Â | 0.91 Â Â Â | 1.76
>
> Signed-off-by: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx>
> ---
> Âdrivers/net/wireless/wl12xx/conf.h | Â 16 ++++++++--------
> Âdrivers/net/wireless/wl12xx/main.c | Â Â4 ++--
> Â2 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/wireless/wl12xx/conf.h b/drivers/net/wireless/wl12xx/conf.h
> index f5c048c..21b72a5 100644
> --- a/drivers/net/wireless/wl12xx/conf.h
> +++ b/drivers/net/wireless/wl12xx/conf.h
> @@ -1084,30 +1084,30 @@ struct conf_scan_settings {
> Â Â Â Â/*
> Â Â Â Â * The minimum time to wait on each channel for active scans
> Â Â Â Â *
> - Â Â Â Â* Range: 0 - 65536 tu
> + Â Â Â Â* Range: u32 tu/1000
> Â Â Â Â */
> - Â Â Â u16 min_dwell_time_active;
> + Â Â Â u32 min_dwell_time_active;
>
> Â Â Â Â/*
> Â Â Â Â * The maximum time to wait on each channel for active scans
> Â Â Â Â *
> - Â Â Â Â* Range: 0 - 65536 tu
> + Â Â Â Â* Range: u32 tu/1000
> Â Â Â Â */
> - Â Â Â u16 max_dwell_time_active;
> + Â Â Â u32 max_dwell_time_active;
>
> Â Â Â Â/*
> Â Â Â Â * The maximum time to wait on each channel for passive scans
> Â Â Â Â *
> - Â Â Â Â* Range: 0 - 65536 tu
> + Â Â Â Â* Range: u32 tu/1000
> Â Â Â Â */
> - Â Â Â u16 min_dwell_time_passive;
> + Â Â Â u32 min_dwell_time_passive;
>
> Â Â Â Â/*
> Â Â Â Â * The maximum time to wait on each channel for passive scans
> Â Â Â Â *
> - Â Â Â Â* Range: 0 - 65536 tu
> + Â Â Â Â* Range: u32 tu/1000
> Â Â Â Â */
> - Â Â Â u16 max_dwell_time_passive;
> + Â Â Â u32 max_dwell_time_passive;
>
> Â Â Â Â/*
> Â Â Â Â * Number of probe requests to transmit on each active scan channel
> diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
> index 863e660..c1814f2 100644
> --- a/drivers/net/wireless/wl12xx/main.c
> +++ b/drivers/net/wireless/wl12xx/main.c
> @@ -279,8 +279,8 @@ static struct conf_drv_settings default_conf = {
> Â Â Â Â.scan = {
>        Â.min_dwell_time_active    Â= 7500,
>        Â.max_dwell_time_active    Â= 30000,
> -        .min_dwell_time_passive    = 30000,
> -        .max_dwell_time_passive    = 60000,
> +        .min_dwell_time_passive    = 100000,
> +        .max_dwell_time_passive    = 100000,
>        Â.num_probe_reqs        = 2,
> Â Â Â Â},
> Â Â Â Â.rf = {
> --
> 1.7.1
>
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