Techniques are disclosed that dynamically allocate communications resources in a wireless communications network, such as a wireless personal area network (WPAN). For instance, a wireless communications device may obtain a resource allocation. This resource allocation includes a time slot (e.g., a TDMA time slot) within a wireless communications medium. The device determines a first portion of the time slot in which it intends to transmit data. Also, the wireless communications device relinquishes a second portion of the time slot that occurs after the first portion of the time slot. Based on this relinquishment, a central controller device may reallocate the second portion of the time slot.