CC1310: LBT doesn't work correctly in carrier sense test

maple liao

Part Number: CC1310

Hey guys,

i am working for the japaness TELEC certification.There is a carrier sense test that the device should stop radio transmission when sense carrier wave. I think the LBT feature can handle this. But i found it not work when testing in the certification lab. I follow the topic https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/923020/ccs-launchxl-cc1352r1-how-to-correctly-set-lbt to set my LBT feature.

But no matter what value i set using api ApiMac_mlmeSetReqUint8(ApiMac_attribute_rssiThreshold, X); My device only stop transmission when carrier generated by signal source larger than -41db. It seemed that the api not work correctly. I use api ApiMac_mlmeGetReqUint8(ApiMac_attribute_rssiThreshold,&m_value); the value is what i have set. The default value is 0xAD . I have used 0xBF, 0xB0 , 0xA1 , 0x9C, while the result remain the same.

My CC1310 software is base on SDK example Ti 15.4-stack coprocessor. How could i implement LBT feature correctly?

over 3 years ago

0 Marie H over 3 years ago

TI__Guru* 81911 points

Hi Maple,

We have not written the TI 15.4-Stack to support the Japan regional regulatory specification. However we recently released SimpleLink CC13xx/CC26xx SDK 6.10 with ARIB support for our CC13x2 and CC13x1 devices. I would recommend you to move to this release.

Cheers,

Marie H

0 maple liao over 3 years ago in reply to Marie H

Prodigy 20 points

Hi Marie,

i just want to use LBT to handle this problem. Ti 15.4-stack coprocessor doesn't support LBT feature ?

0 Marie H over 3 years ago in reply to maple liao

TI__Guru* 81911 points

Hi Maple,

Yes, if you select an EU band the TI 15.4-Stack will use LBT.

Cheers,

Marie H

0 Nikolaj_G over 3 years ago

TI__Expert 4425 points

Hi Maple,

Can you provide the steps to reproduce your issue? Preferably based on an example in the SDK.

maple liao said:
ApiMac_mlmeSetReqUint8(ApiMac_attribute_rssiThreshold, X

Are you setting this attribute on the Linux/host side or on the embedded/coprocessor side?

maple liao said:
My device only stop transmission when carrier generated by signal source larger than -41db

Which transmissions are you using for this test? I believe beacons will be transmitted without the use of LBT (or CSMA-CA). So if you are seeing that the device transmits beacon messages irrespectively of the ApiMac_attribute_rssiThreshold value, then this might be the reason.

Thanks,
Nikolaj

0 maple liao over 3 years ago in reply to Marie H

Prodigy 20 points

the band i am using for test is 920.0 ~920.8. You mean that my band doesn't support LBT ?

0 maple liao over 3 years ago in reply to Nikolaj_G

Prodigy 20 points

i call ApiMac_mlmeSetReqUint8(ApiMac_attribute_rssiThreshold, X in CC1310 coprocessor side.

in function MtMac_commandProcessing(Mt_mpb_t *pMpb), every times before i call macDataReq() i set ApiMac_mlmeSetReqUint8(ApiMac_attribute_rssiThreshold).

uint8_t MtMac_commandProcessing(Mt_mpb_t *pMpb)
{
    uint8_t status = ApiMac_status_success;

    switch(pMpb->cmd1)
    {
        case MT_MAC_RESET_REQ:
            macResetReq(pMpb);
            break;

        case MT_MAC_INIT_REQ:
            macInitReq(pMpb);
            break;

        case MT_MAC_START_REQ:
            macStartReq(pMpb);
            break;

        case MT_MAC_DATA_REQ:
            m_status = ApiMac_mlmeSetReqUint8(ApiMac_attribute_rssiThreshold, 0x9C);  //lbt rssi set to BF -65, B0 -80 ,  A1 -95 , 9C -100
            ApiMac_mlmeGetReqUint8(ApiMac_attribute_rssiThreshold,&m_value);
            macDataReq(pMpb);
            break;

I use a non-beacon mode so it may not beacons. The LBT do stop the transmission when the LAB signal output device generate signal lager than -41db. But if the output is less than 42db, my board start to transmission again. So i believe that there is problem when i set the LBT rssi threshold.

0 Nikolaj_G over 3 years ago in reply to maple liao

TI__Expert 4425 points

Hi Maple,

Only the EU band (863 MHz) use LBT. See https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/1088626/cc1310-cc1310-lbt-afa-fh-mode.

All other bands uses CSMA-CA.

Regards,
Nikolaj

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CC1310: LBT doesn't work correctly in carrier sense test