5 Replies Latest reply on Oct 19, 2020 6:47 AM by JBl_4798731

    Why do I only get 5 GHz networks?

    JBl_4798731

      Hello,

       

      I am using the `wiced_wifi_scan_networks` call to scan networks (obviously) but if I am in a place with 20+ networks around I only ever get 5GHz networks in the scan results callback. If there are only a handful of networks it seems to work just fine but when there are several I only get 5GHz networks. It seems like a bug with the WICED API. I see in the logs that it scans other networks but they are never passed to the callback.

       

      I see dozzens of logs that look like this

       

      3120034: Event (interface, type, status, reason): WWD_STA_INTERFACE WLC_E_ESCAN_RESULT WLC_E_STATUS_PARTIAL WLC_E_REASON_INITIAL_ASSOC

      Scan result: channel=0 signal=-58 ssid=backup-XX:XX:XX:XX:XX:XX bssid=XX:XX:XX:XX:XX:XX

       

      and my callback gets hit a few times but never for that backup-XX:XX:XX:XX:XX:XX ap.

       

      Thank you for your help!

        • 1. Re: Why do I only get 5 GHz networks?
          MuraliR_36

          Hello JBl_4798731

           

          Are you using the default snip.scan application or do you have a custom application where you are facing this issue? If its a custom app, can you share it? Which is the chip that you are using? Are you using WICED? If so what version?  Also what is the Network Stack-OS combination?

           

          Can you try increasing the Channel Dwell time and check if you are able to get all the networks?

           

          Thanks

          • 2. Re: Why do I only get 5 GHz networks?
            JBl_4798731

            Thank you for your response.

             

             

            Are you using the default snip.scan application or do you have a custom application where you are facing this issue? If its a custom app, can you share it?

            I am using a custom app that I am not able to share.

            Which is the chip that you are using?

            CYW43907

            Are you using WICED? If so what version?

            Yes, WICED SDK 3.4.0.

            Also, what is the Network Stack-OS combination?

            We are using the Thread-X OS

            Can you try increasing the Channel Dwell time and check if you are able to get all the networks?

            Increasing the Channel Dwell time does increase the number of networks I get in the callback and it does include both 5 and 2.4 GHz networks. What is a reasonable value for that to be though? Do I just need to do some guess and checking or are there some guidelines and/or starting times? Right now I am at 500 ms for each option.

             

            extParams.number_of_probes_per_channel                                       = 6;

            extParams.scan_active_dwell_time_per_channel_ms                        = 500;

            extParams.scan_passive_dwell_time_per_channel_ms                      = 500;

            extParams.scan_home_channel_dwell_time_between_channels_ms = 500;

            • 3. Re: Why do I only get 5 GHz networks?
              vipr_513046

              I suspect there's a fixed size scan result buffer (20) on the WICED host or your custom app. Since 5G channels are scanned first, if you run out of buffer space, then any incoming 2G scan results will be dropped.

              • 4. Re: Why do I only get 5 GHz networks?
                MuraliR_36

                JBl_4798731 There's no standard guidelines as such on setting the dwell time. You need to figure out the dwell time based on the time you want the scan to complete and the number of results needed. Also as vipr_513046 said increasing the Buffer of the scan results may also help.

                1 of 1 people found this helpful
                • 5. Re: Why do I only get 5 GHz networks?
                  JBl_4798731

                  Thank you both so much for the responses. If I increase the dwell time i do get back around 22-25 results (there are 26 that I counted) so I beleive the buffer is greater than 20 but my last question is the scan results have a `next` field that never points to anything. It looks like it is a linked list of 1 always. Is there a way I can increase that?