1. Introduction

           DFS is Dynamic Frequency Selection, which is a function of using 5 GHz Wi-Fi frequencies that are generally reserved for radar, such as military radar, satellite communication, and weather radar. The DFS channels vary from country to country. The main benefit to use DFS channels is to increase the number of Wi-Fi channels. It is legally required Channel Availability Check process to prevent electromagnetic interference the 5 GHz frequency with the radar. If any radar signal detects, it will switch from DFS channel to non-DFS channel automatically(If driver have DFS support) .

2. Scope

          The scope of this work is to integrate the DFS Feature in RPI reference platforms.This document covers only integration not validation.

3. Target Audience  

  • RDK-B Operators
  • RDK-B SoC Vendors
  • RDK-B OEM's
  • RDK-B Application Vendors
  • RDK-B System Integrators 

4. Supported device  

  • Raspberry Pi4 32 bit
  • Raspberry Pi4 64 bit

5. Supported dongle

6. Build Instructions

TargetYocto versionBuild instruction
RPI4 32bitDunfell RPI 4B Model Reference Platform
RPI4 32bitKirkstonekirkstone RDK-B RPI4 32 bit
RPI4 64bitDunfellRPI 4B Model Reference Platform with 64bit Arch
RPI4 64bitKirkstoneKirkstone RDK-B RPI4 64 bit (Both User Space & Kernel Space)

7. High Level Design

8. TR-181 Data Model Parameters

ModuleTR-181 DM parameterPurpose
CcspPandMdmcli eRT setv Device.DeviceInfo.X_RDKCENTRAL-COM_RFC.Feature.DFS.Enable bool trueenable/disable the DFS feature.

By default, it should be disabled.
OneWifidmcli eRT getv Device.WiFi.Radio.2.X_COMCAST_COM_DFSEnableThis should be enabled after executed the above command.
dmcli eRT setv Device.WiFi.Radio.2.Channel uint 100Setting DFS channel value
dmcli eRT setv Device.WiFi.ApplyRadioSettings bool trueApplying radio settings
dmcli eRT setv Device.WiFi.SSID.2.Enable bool false 
dmcli eRT setv Device.WiFi.SSID.2.Enable bool true
Re-enable the AP for updating the new channel value in realtek drivers.
dmcli eRT setv Device.WiFi.ApplyAccessPointSettings bool trueApplying AP settings

9. Test Procedure and Test Results

        1. Enabling the DFS feature in RPI Router. By default, it's disabled.


       2. Getting the current 5G Radio channel


       3. Connected Client info


          4.Changing the 5G channel value from non-dfs to dfs frequency


          5. Re-enable the AP/Radio to update the new channel value in realtek driver


         6. Connected client info with DFS frequency


            Tested Image :

Tested Image
root@RaspberryPi-Gateway:/# cat version.txt 
BUILD_TIME="2024-06-05 11:04:58"
Generated on Wed Jun 05  11:04:58 UTC 2024

10. Feature Validation

                    TBD - We didn't validate this feature with RADAR signals   .

11. Limitations

               This rtl88x2bu driver doesn't have the channel switch support. So, we need to do the re-enable of AP/Radio whenever we switching the new channel .

12. References

REFPLTB-2925 - Getting issue details... STATUS

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