A method of determining a location of a mobile device in a system having a plurality of fixed transmitters includes: obtaining, at the mobile device, inference model data defining a plurality of node operations; collecting, at the mobile device, respective proximity indicators corresponding to a subset of the fixed transmitters, each proximity indicator representing a proximity of the mobile device to the respective fixed transmitter; at the mobile device, generating a location according to the proximity indicators and the node operations; and presenting the location.