WiLink8 Feature Guide/AP DFS Master

Supported from version ol_r8.a9.14 (R8.4) and above

Feture Description

• AP can now work on DFS channels according to the regulatory domain.
• AP has the capability to perform channel availability check prior to operating on a DFS channel.
• AP has the capability to detect radars during operation on a DFS channel.
• Upon radar detection the AP will move to a randomly selected channel.

-STA(s) that were connected to the AP on a DFS channel will receive a CSA in the AP beacons.

Setup & Configuration

Operating AP on DFS channel is done with the ‘user-scripts’ provided by TI.
These scripts can be used as a reference of how to operate the AP DFS Master feature, and their usage is described below.
Note that these scripts is used also for running AP on non DFS channel as well.
The configuration parameters of the hostapd are located in a configuration file called ‘hostapd.conf’ (R8.5 only: There are two such configuration files for supporting the mBSSID feature).
These files are provided by TI and may be modified to meet the product requirements. However – there are some parameters needed to be modified in order to support AP DFS Master,
as mentioned below, and these parameters must be set in order for the feature to function correctly.

Configure the hostapd.conf files as follows (R8.5 only: for mBSSID support on DFS channel please consider also the requirements in the following link: mBSSID Support:

Attribute/File	hostapd.conf	Comments
hw_mode	a	DFS is operational on A band only
country_code	Pick a country	For example: US
channel	Pick channel according to the HW mode and the country code selected	Channel must be supported in the selected country
ieee802.11d	1
ieee802.11h	1
basic_rates	60 120 240	Default values are: 10 20 55 110 60 120 240. Change is required to operate on 5G band.

User Guide & Examples

During mBSSID mode, each AP has it’s own network interface. The first AP network interface is named “wlan1” and the second AP network interface is named “wlan2”.
Note that these names must be configured in the hostapd.conf files accordingly (see above in setup & configuration).
Each AP is assigned with a unique MAC address. The MAC address is derived from the chip basic MAC address and is incremented serially.
For example if the basic MAC is E0:C7:9D:2D:AA:CC then the first AP will be assigned with E0:C7:9D:2D:AA:CD and the second with E0:C7:9D:2D:AA:CE.

Following are the script and flow used for operation on DFS channel: 1. Start the AP: ap_start.sh 2. Wait 60 seconds for the channel availability check to be completed and AP to be enabled 3. If a radar was detected on the AP channel:

-New Channel is randomly selected

-AP perform channel switch

Radar Simulation: There is a debug option to simulate a radar detection on a specific DFS channel:
Example:

echo 60 > /sys/kernel/debug/ieee80211/phy0/wlcore/wl18xx/radar_detection

Changing Non-Occupancy-Period (NOP): To edit the 'NOP' time, load cfg80211 modules with the desired parameters:
dfs_nop_time_ms - Non Occupying Period in ms, Default is 1,800,000.
dfs_cac_time_ms – CAC time in ms, Default is 60,000.
Example:

modprobe cfg80211.ko dfs_nop_time_ms=60000 dfs_cac_time_ms=10000

Note: this requires a driver reloading.

Enable/Disable test mode: Allows testing radar detection without switching channels
echo 8 > /proc/sys/kernel/printk
Disable: echo 0 > /sys/kernel/debug/ieee80211/phy0/wlcore/wl18xx/radar_debug_mode
Enable: echo 1 > /sys/kernel/debug/ieee80211/phy0/wlcore/wl18xx/radar_debug_mode

Errata/Limitations

Multi Role is not supported when working as DFS Master.