A mobile device that can use both data from a GPS or other GNSS receiver and signals from a wireless network to provide location based services based on the location of the mobile device is controlled at least partly by a locationing resource control module in the wireless network. The module provides network-assisted optimization of utilization of the GPS receiver and other resources by activating the GPS receiver and associated components when fine resolution location data is needed for provision of the location based services, and deactivating the GPS components when coarse resolution will suffice. The selective control of the GPS components is performed in the wireless network in response to receipt from the mobile device of location requisition data, conditions specifying what actions are to be performed by the mobile device, and current location data from the wireless network. The wireless network may also specify and prioritize at least some conditions.