Difference between OT_RADIO_CAPS_TRANSMIT_RETRIES & OT_RADIO_CAPS_CSMA_BACKOFF Radio capability

[AhmedEsmailm]

Hello OT team,

The below description for OT_RADIO_CAPS_TRANSMIT_RETRIES & OT_RADIO_CAPS_CSMA_BACKOFF capabilities are mentioned in API reference and Radio .h
OT_RADIO_CAPS_CSMA_BACKOFF | Radio supports CSMA backoff for frame transmission (but no retry).
OT_RADIO_CAPS_TRANSMIT_RETRIES | Radio supports tx retry logic with collision avoidance (CSMA).

I understand from this description that OT_RADIO_CAPS_CSMA_BACKOFF should be set for the radio driver that supports backoff but doesn't implement the CSMA retry. while OT_RADIO_CAPS_TRANSMIT_RETRIES should be set for radio driver that implements CSMA retries. Based on that, only of these capabilities should be set for certain radio driver. i.e if OT_RADIO_CAPS_TRANSMIT_RETRIES is supported then this implies that OT_RADIO_CAPS_CSMA_BACKOFF is supported as part on it and the OT_RADIO_CAPS_CSMA_BACKOFF shouldn't be set.

Could you please confirm my understanding

Thanks in advance,
Ahmed Ismail

Thanks,
Ahmed Ismail

[abtink]

A radio supporting OT_RADIO_CAPS_TRANSMIT_RETRIES should also already support OT_RADIO_CAPS_CSMA_BACKOFF (and OT_RADIO_CAPS_ACK_TIMEOUT).

I recommend including all these capabilities in the otPlatRadioGetCaps() return value for such a case. This ensures that GetCaps() accurately represents all supported capabilities.

The OT stack may not explicitly check for OT_RADIO_CAPS_CSMA_BACKOFF if OT_RADIO_CAPS_TRANSMIT_RETRIES is present, but it won't be a good idea to assume this in radio platform implementation (and exclude the OT_RADIO_CAPS_CSMA_BACKOFF in GetCaps()).

[AhmedEsmailm]

Thanks for the info