Workshop on Advances in Global and Local Positioning: Positioning with OFDM Based 4G Communications Signals

Kurzfassung

Positioning in wireless networks will play a fundamental role in future communications systems where user- and system-side applications can benefit from the knowledge of the mobile station (MS) position. As stand-alone solution or as complementary extension of global navigation satellite systems (GNSSs), wireless network based positioning usually makes use of timing measurements, e.g., time difference of arrival (TDoA). Obtaining timing measurements from the communications signals directly results in a link level synchronization problem where the arrival time of signals transmitted from the base station (BS) has to be measured at the MS. For code division multiple access (CDMA) these algorithms and their positioning capabilities are well studied. However, the performance in orthogonal frequency division multiplexing (OFDM) based systems - especially in multipath environments - is of particular interest because of the future relevance of this modulation scheme for 3GPP-LTE and 4G mobile communications systems. In this presentation, different link level OFDM synchronization algorithms are analyzed with respect to their positioning capabilities and simulation results show the performance in typical urban environments. Additionally, the impact of the link level synchronization accuracy on the overall positioning error - where measurements from at least three BSs have to be combined - is investigated.