Hi Thomas, thank you for your reply.
I read the presentation and found there a partial reply to my question: it is written that the current version of FHSS SimpliciTI implementation is not compatible with sleeping devices.
I cannot understand, however, why sleeping devices are mentioned only in the section discussing startup problems: a device can be programmed to go sleeping only after startup , so startup can not be considered an issue for sleeping device.
Generally, I was not able to get a feel for ultra low power problems in SimpliciTI FHSS.