An asynchronous medium access control layer scheduler increases efficiency for directional mesh networks by removing extra overhead in the time slots. The efficiency is increased by dividing time slots into sub-slots to allow for a receiving node to be offset by at least one sub-slot from the transmitting node. This enables the scheduler to more efficiently schedule operations for the nodes so that nodes can be performing other functions rather than waiting to receive a transmission or waiting after transmitting a transmission. The sub-slots may be sized to approximate the transmission propagation time or time of flight delay.