Resource allocation in a wireless data system determines a load condition of the system and adapts a target quality of service (QoS) characteristic, accordingly. Data transmission parameters may be assigned, or adapted, for the wireless units based on the adapted target QoS characteristics. Resources are allocated to data transmissions between wireless units based on these parameters. As the system load decreases, the target QoS characteristic is adapted so that more resources will be allocated to the wireless unit, and the QoS will improve. The adapted QoS threshold may be a data error rate or target fill efficiency for each wireless unit.