ASSISTED POSITIONING SYSTEMS

A position determining unit has an assistance data processing and relaying module (software client) (1318) that obtains localised assistance data, such as Global Navigation Satellite Systems (GNSS) assistance data and/or non-GNSS (such as Wireless Positioning System) assistance data, from an assisting peer position determining unit and relays the localised assistance data to an assisted peer position determining unit. The relaying may be done via an assistance server. In a relaying GNSS position determining unit, such as a GPS receiver, the chip (1310) architecture has multi-frequency GNSS baseband (1311), GSM or UMTS baseband (1312) for long range communication and short range baseband (1313) such as Bluetooth or Wi-Fi or UWB. The assistance data generating module (1316) generates localised assistance data at the relaying GNSS unit from the GNSS R.F. front end and/or GNSS baseband and/or microcontroller running the GNSS solutions software portion. The assistance data feed module (1317) supplies assistance data to any combination of the main modules of the GNSS position determining unit. The supplied assistance data may originate in the relaying GNSS unit itself or the assisting GNSS unit.