A method, apparatus and system for medium access control is provided. Time slots configured to include mini slots at the beginnings thereof. Devices are assigned time slot, mini slot combinations as transmission opportunities. A device can attempt to use a transmission opportunity when it has a packet to send, by beginning data transmission in its assigned slot and mini slot and potentially continuing the transmission up until the end of the assigned slot. If another device is already transmitting in the assigned slot, the device refrains from using its transmission opportunity. Higher priority devices can be assigned transmission opportunities corresponding to earlier mini slots within a slot. In some embodiments, multiple devices can be assigned the same transmission opportunity and a collision detection mechanism can be employed. In some embodiments, all devices detect if a slot is idle and advance the beginning of the next slot upon such detection.