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AIROC™ Wi-Fi and Wi-Fi Bluetooth Combos

Dhaval
New Contributor

@Hello Support team,

We have designed a custom board with NXP I.MXRT1020 MCU and Murata 1MW using freeRTOS. We have an application running on RT1020 which scans the Wi-Fi network and joins the network whose RSSI is better. The software will then continuously performing the ping on google server to verify internet connectivity and communicate with cloud.

Wi-Fi : 1MW
Wi-Fi firmware Version: wl0: Jan 8 2021 06:48:16 version 7.45.230 (984c094 CY) FWID 01-4ab01959
Antenna: Internal antenna as per 1MW certified chip antenna
Host MCU: NXP I.MXRT1020
SDK: WICED with freeRTOS

 Setup Information:

We are facing an issue with wi-fi connection stability and packet drop. Device is connected to office wifi mesh infrastructure. Device is 17 Ft away from closest mesh node. Other mesh nodes are 25-30 Ft away. Device is getting ASYNCEVENT with event_type is WLC_E_AUTH and event reason WLC_E_REASON_INITIAL_ASSOC and after that TCP connection with cloud server breaks every time. Device is getting such event and dropping off at 7-8 times per hours at same steady position. 

Debug Logs:
| wwd_wifi.c           | | 2525 | Callback from Function: In wiced_join_events_handler() line 2355
| wifi_handle.c        | | 0182 | Joined a network
| wwd_wifi.c           | | 2525 | Callback from Function: In wiced_join_events_handler() line 2355
| wifi_handle.c        | | 0182 | Joined a network
| wwd_wifi.c           | | 2525 | Callback from Function: In wiced_join_events_handler() line 2355
| wifi_handle.c        | | 0182 | Joined a network

Trace from debugger:

 

Dhaval_0-1634018445968.png

 

 

Antenna:

Let me correct myself for Antenna part, We have used PCB Trace Antenna as per below recommendation from Murata.

 Type1MW_certification_antenna_design_P2ML6161.dxf followed for Antenna design

Dhaval_1-1634018445970.png

 

Experiment-1:

Design product will be mounted on wall/table top, which will be always steady after installation. We have tried tweaking below roam setting and that help us to lower down the wifi reassociation and tcp socket connection drop instance. But that note completely resolve disconnection and packet drop.

Roam updated setting:

/* Configure roaming parameters */ //Original WICED roam settings commented
//wwd_wifi_set_roam_trigger( WICED_WIFI_ROAMING_TRIGGER_MODE );
//wwd_wifi_set_roam_delta( WICED_WIFI_ROAMING_TRIGGER_DELTA_IN_DBM );
//wwd_wifi_set_roam_scan_period( WICED_WIFI_ROAMING_SCAN_PERIOD_IN_SECONDS );

/* New setting for roam trigger */
wwd_wifi_set_roam_trigger(-90); //roam trigger set to -90 dBm
wwd_wifi_set_roam_delta(70); //roam delta set to 70
wwd_wifi_set_roam_scan_period( 100 ); //100 seconds roam scan period

Can you suggest what other parameters/configuration to tweak to have optimal performance for wifi connectivity in mesh network, Repeater and extender network or dedicated AP network according to our product usecase?
 

Regards,

Dhaval

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4 Replies
MuraliR_36
Moderator
Moderator

@Dhaval The optimal performance for the product will depend on the environment and the design of the product and the optimal number can be determined through trial and error.

Now since you say that the connection drop rate fell when RSSI rate was reduced and the roam delta was increased, this indicates that, the mesh environment that you have, might be causing the this. Have you tried this in a single AP setup area? Was it better then?

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Dhaval
New Contributor

Thanks for the response.

Use case:

As mentioned above, device will be installed on steady position in health care environment. Device will be wall mounter or table top position and will be connected over health care Wi-Fi facility.

- We have completely off the Wi-Fi roam using below API and that lower down the drop-off and Wi-Fi re-association in mesh network.  

/* New setting for roam trigger, roam off completely */
    wwd_wifi_turn_off_roam(WICED_TRUE);

Queries:

  1. Is it advisable to completely off the roam feature as per our device use case?
  2. Can you please suggest what other parameters/configuration to have optimal performance for Wi-Fi connectivity in mesh network, Repeater/extender network without repeated re-connection in our product use case?

 

Regards,

Dhaval

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MuraliR_36
Moderator
Moderator

1. If you are sure that RSSI won't drop to the level where the connection disconnects, then it should be fine.

2. You could probably fine tune the power numbers of the device by fine tuning the NVRAM and the CLM BLOB. The module vendor should be able to help you out here.

PS: I went through the problem description again. have you investigated why the RSSI from the router nearest to the device is dropping off which is resulting in the WIFI client roaming? The behavior of the WIFI client is as expected where, if it sees a drop in RSSI, it switches to the best AP available.

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Dhaval
New Contributor

Thanks for the response. Please find below inline comments. 

  1. If you are sure that RSSI won't drop to the level where the connection disconnects, then it should be fine. 

Device firmware handles Wi-Fi AP disconnections as below : 

Example Cases – 

  • On power-up state, device will scan the available nearby AP and connect to the highest RSSI strength node. Device will keep communicating through connected AP as far device can send telemetry data to cloud.  Device will keep sending Ping(ICMP) request to server in background and on consecutive ping failure/timeout(for defined period), device will disconnect current AP and again start scanning & perform reconnection process.
  • On power-up, device is connected with closest mesh node “Node1” with -65 RSSI and later, Node1 is power-down or STA disconnect due to some reason (i.e. power failure, RSSI drop). In this case , device will scan and find available mesh nodes, and will connect with mesh node with highest RSSI. 

 

  1. You could probably fine tune the power numbers of the device by fine tuning the NVRAM and the CLM BLOB. The module vendor should be able to help you out here. 

Okay, we will refer the NVRAM parameters and contact vendor for optimal settings of TX Power. 

 

PS: I went through the problem description again. have you investigated why the RSSI from the router nearest to the device is dropping off which is resulting in the WIFI client roaming? The behavior of the WIFI client is as expected where, if it sees a drop in RSSI, it switches to the best AP available. 

We are not seeing some re-association in case of dedicate AP. Default setting for roam in WICED is roam trigger set to ‘WICED_WIFI_OPTIMIZE_BANDWIDTH_ROAMING_TRIGGER’ with roam delta in 5 dBm and 10 second scan period. 

Let’s take an example of mesh network where device is located at overlapping region of having 3 mesh nodes at approximately same distance with around -70 RSSI. During peak hours Wi-Fi RSSI can be vary of +- 5 dBm and that will cause Wi-Fi roam trigger and can-do frequent re-association.  

 

Regards.

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