The widespread commercial availability of location-based services depends upon every new mobile phone including positioning capability. The timescales for the introduction of these devices is far from clear, and yet the demand for high accuracy services is already increasing, particularly in the automotive and telematics sector. This paper presents a summary of the current and emerging positioning technologies, their capability, predicted timescales and their suitability for the in-car environment. Will GPS levels of accuracy be available in the mobile phone? Who are the various commercial players that may affect the ultimate choice of technology? Have new satellite services such as Galileo left it too late? The paper attempts to answer these and other questions whilst offering an insight into the convergence of satellite and cellular positioning.

In many combined GPS/cellular radio receivers, the cellular radio segment is not used to aid the positioning process. Recently proposed Assisted-GPS systems use the communications channel to improve receiver time-to-first-fix and the GPS tracking sensitivity. However, the cellular radio signals can also be used for locating the receiver. Studies using the GSM mobile communication system have shown positional accuracy comparable to that of SA-degraded GPS. To achieve maximum performance (accuracy, availability, integrity and reliability), both sources of positioning information, GPS and cellular, should be regarded as sensor inputs to an integrated navigation system. In this way the benefits of both systems can be fully exploited to produce an optimal navigation solution.