A mobile radio device uses its own location/position information to itself select a radio access resource from a plurality of radio access resources shared among a plurality of mobile radio devices; and sends a transmission on a wireless shared radio access channel using the selected radio access resource. In non-limiting embodiments: the location/position information represents global/absolute physical position, or a position relative to a local reference location within an access region which may be a cell, building, roadway, etc.; and the radio access resources are time slots; frequency blocks; and/or preambles. The examples have a map or algorithm stored in the device's local memory that associates different access resources to different discrete location areas within the access region; the algorithm identifies the location area that corresponds to the location/position information and outputs the selected access resource (or an index/identifier of it) associated with the identified location area.