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CC3100SDK: Average RSSI vs SSID's RSSI

Part Number: CC3100SDK

Hello 

Based on the documentation, it is my understanding that the average RSSI from WlanRxStatGet is the average RSSI when sending data directly over the WLAN MAC layer without being connected to an Access Point. Is this correct?

If so, it seems that the average RSSI should not be used when wanting to know the RSSI for a given SSID (Access point).  So, it seems that the network list has to be retrieved, find the desired SSID and then obtain the RSSI like demonstrated in the antenna selection example . Is this correct?

Also, what is the difference between the RSSI for given SSID and the average RSSI? Is the RSSI for a SSID an average or the current value at the time the network list is retrieved?  Is it possible to obtain an average RSSI for a given SSID (Access Point)?

Thank you.

Steve

  • Hi Steve,

    No, I believe the documentation is a bit misleading on this point. It is possible to collect the average RSSI (for management and data frames) while connected to an access point using the receive statistics mechanism. You do not have to use the network list if you are trying to collect RSSI information about the AP to which your SimpleLink station is currently connected.

    The difference is that the RSSI reported with the network list (for a specific SSID) is calculated based on the activity during the scan. The results of the scan are stored until they are read by the host or updated (in the case of a periodic scan), so the RSSI is not necessarily the value when the list is retrieved. The average RSSI from the RX statistics mechanism is averaged across data and management frames separately and reading the statistics clears (resets) the values.

    Best Regards,
    Ben M
  • Hello Ben

    Thank you for the clarification. I have some follow up questions.

    1) The transceiver mode example is establishing a socket connection using a SL_SOCK_RAW and a specific channel before retrieving the average RSSI. However, it is my understanding that the average RSSI for an access point would be retrieved after performing a sl_WlanConnect to a specific access point. Is this correct?

    2) What are the use cases for the need of average RSSI for management frames and average RSSI for data frames? Which is of more importance?

    3) To confirm, do you mean the average RSSI for a scan is retrieved and stored during sl_WlanPolicySet. Then sl_WlanGetNetworkList will retrieve the stored value. Is this correct?

    Thank you .

    Best Regards,
    Steve Paulus
  • Hi Steve,

    1) Yes, your understanding is correct on the two different approaches for examining the statistics. Typically these are each applied to different types of applications.

    2) The main reason these two are separated is because it can be more useful to examine the RSSI for data when looking at things like throughput experienced by the application. Data packets are often sent at different rates than management frames and may have a slightly different RSSI. The information is mostly separated for use in internal mechanisms of the network processor subsystem, but it is also made available to the user this way.

    3) Not necessarily when sl_WlanPolicySet() is called, but yes whenever the scan results are collected. Though the value is seen by the application host when retrieved using sl_WlanGetNetworkList().

    Best,
    Ben M
  • Hello Ben

    Thank you for the clarification and answering my questions.

    Best Regards,

    Steve Paulus