How to get rssi

Hi Nir,

Do you have any plan to support RSSI in connection mode?

Thanks,

Park,

Hi Park,

The RSSI is not part of a normal IP packet and in order to support BSD Socket functions you must provide only the data buffer without overhead.

This is why we have the transceiver mode. on our roadmap we would like to support transceiver in connect mode but this is not something I can commit for a schedule.

Hi Nir,

User want to check signal strength, that's why i need to know rssi in STA connection mode.
As far as i know, other wifi chipset can display rssi in STA connection mode.

Thanks,
Park

Hi Park,

I guess your question is regarding signal strength of the the Access Points to which CC31xx/CC32xx STA is connected to.

I guess in general, you can get rssi of upto 20 visible APs .See below

=======================================================================================

sl_WlanPolicySet(SL_POLICY_SCAN , policyOpt,(unsigned char *)(IntervalVal), sizeof(IntervalVal)); 

// delay 1 second to verify scan is started
osi_Sleep(1000);

sl_WlanGetNetworkList(0, SCAN_TABLE_SIZE, netEntries);

=======================================================================================

Now you have rssi of all the visible APs. From the netEntries array, you can get rssi of the AP you are connected to.

Regards,

Kaushal

Hi Park,

Your first query was how to get RSSI of the last packet which is not part of the packet.

 However getting the connected signal strength (RSSI) with the AP is possible in a simple way by using the Rx Statistics. Management RSSI can indicate the Beacons frame coming from the AP.

Please follow the Programmer’s guide for more info.

Below is a short exmaple:

sl_WlanRxStatStart();// start collecting Rx Statistics data

sl_WlanRxStatGet(&gRxStatResp,0);// Read statistics

       printf("\n\n*********************************Rx Statistics**********************************\n\n");

printf("Received Packets - %d\n",rxStatResp->ReceivedValidPacketsNumber);

       printf("Average Rssi for management: %d\nAverage Rssi for other packets: %d\n",rxStatResp->AvarageMgMntRssi,rxStatResp->AvarageDataCtrlRssi);

You can also print the RSSI Histogram of the last received packets.

I hope it answers your question.

Best Regards,

Nir Nitzani

Hi Nir,

According to your guide i can get rssi value in connection state. 
but both avgMgmt and avgDataCtrl rssi values are fluctuated as below.
Can i get stable rssi of rx packet from connected AP?
Should i use rx filter to get stable rssi?

count=10 Mgmt=-43 DataCtrl=-66
count=17 Mgmt=-65 DataCtrl=-38
count=23 Mgmt=-66 DataCtrl=-70

Thanks,
Park

Hi Nir,

I solved my problem (reporting stable rssi).

Many Thanks,
Park

Hi Park,

can you describe a bit how you have solved it?

Best regards,

Martin

Hello Nir,

From your last post it seems you are saying that Rx Statistics can be gathered while connected to an AP? This wiki page: "http://processors.wiki.ti.com/index.php/CC32xx_Transceiver_Mode" says that Rx Statistics can only be used in transceiver/disconnected mode however section 17.4 of document SWRU368 seems to say otherwise.  

I'm trying to understand whether I can gather RSSI data from a particular AP using Rx Statistics in a low power state i.e. LPDS mode with the network processor only waking up for beacons?

Regards

Hi Martin,

1. Please refer to chapter 17.3 of SWRU368 doc.

    When calling only sl_WlanRxStatGet, without the start command, only the RSSI is available.

2. In order to receive packet, you may need to use SL_ALWAYS_ON_POLICY.

Thanks,
Park

Hi Park - you are correct - as written in the programmer's guide - Rx Statistics is supported in connection mode as well. 

While the STA is connected Beacons are continue to be received and RSSI is collected - no need to change the Power Management mode. when Data packets will be received the device will switch to Active state automatically and again RSSI data will be collected.

Lotus I think you have identified a mistake in our WiKi documentation which will be fixed. in this case the programmer's guide is the correct one to use.

thank you both.

Nir Nitzani

Hello Kaushal,

I implemented your idea.

After executing  the function sl_WlanGetNetworkList(0, SCAN_TABLE_SIZE, netEntries);

i am getting the information of all AP's.

In the netEntries structure, the netEntries.rssi shows the values 0xBB, 0xBC etc...

My question is, how do i know what the signal strength is from the RSSI value of the AP ??

I want to indicate when the signal strength falls below 20%.

Please reply.

Warm regards,

Abhishek.

Hi Kaushal,

I could see some time duplicate networks in the list of entries. In that case which network RSSI value we should consider it as valid one.

Thanks,

Ashok