Xmac: Duty cycle parameter

[SEDE]

Hello everyone,

I am new in OMNET++ and trying to implement my MAC protocol using inet framework.

Can anyone please tell me for XMAC, which parameter actually represents the duty cycle of the nodes? In other word, how i can set duty cycle of the nodes for xmac?

Besides, in XMAC, i have found a method peekatfront (as below) is being used. Can anyone tell me what is the function of this method here?

if (msg->getKind() == XMAC_PREAMBLE) {
            auto incoming_preamble = check_and_cast<Packet *>(msg)->peekAtFront<XMacControlFrame>();

Hope, I will get your response.

Kind Regards,