Ville Valtteri Ranki

Hybrid positioning system combining angle-based localization, pedestrian dead reckoning and map filtering

We present a hybrid indoor positioning solution combining angle-based localization, pedestrian dead reckoning, and map filtering. The angle-based localization system provides absolute location estimates, whereas pedestrian dead reckoning (PDR) results in accurate shape and length of the traversed route without absolute location and heading information. PDR movement and angle-based location estimates are fused together with a building vector map in a fusion filter, which in this study is implemented through a particle filter. When the fusion filter has been initialized with absolute position data and has converged, it can run also on PDR and map filtering, independently of the angle-based localization system, in areas that are not illuminated by multi-antenna arrays. In principle the same fusion design could accommodate location estimates also from other positioning sources, for example WiFi, or GPS in outdoor-to-indoor transitions. By combining information from various positioning modalities, different types of indoor environments can be provided with seamless positioning coverage with reasonable accuracy and infrastructural investments.

Angle-based indoor positioning system for open indoor environments

In this paper we present a Direction-of-Arrival (DoA) based system which is used for indoor positioning applications. The proposed system has been designed for locating transmitter tags/mobile phones in open indoor locations, such as conference centers, expo areas, and warehouses. A description of both the system architecture and the DoA-based indoor-positioning algorithm are given. In order to demonstrate the system performance, real-world measurements have been carried out. As shown by experimental results, the proposed system provides reliable indoor positioning estimates.

Phase Noise in Beamforming

In this article we examine the effect of phase noise on a multi-antenna beamforming system. The effect is quantified in terms of error vector magnitude (EVM). It is shown that using independent phase noise sources improves EVM performance in the main lobe. It is further shown that when forming beams using antenna amplitude attenuation (tapering) for groups of correlated noise sources, lowest EVM is obtained when correlated noise sources are assigned to tapered amplitudes in a way which minimizes the differences between the sums of the tapering coefficients of the groups. Bounds for the variance of the phase noise in the main lobe are provided. Further a method achieving secure communication by forming a secure beam by adding uncorrelated phase noise to the antenna elements is presented.