This disclosure provides systems, methods and apparatuses for coordinating access to a shared wireless medium among multiple master devices operating on the same frequency band. In some implementations, master devices may contend for access to the shared medium during a medium reservation window (MRW). During the MRW, master devices may advertise their intent to reserve at least a portion of the shared medium for one or more timeslots within a subsequent medium utilization period. The reservation messages may be broadcast to other master devices in the vicinity to prevent other master devices from accessing the wireless medium during a reserved timeslot. In some implementations, the owner of a timeslot may share at least a portion of its timeslot with other master devices. For example, the timeslot owner may enable other master devices to utilize an unused portion of the wireless medium, such as unused channels, spatial streams, or time.