Miniaturised microstrip bandpass filter using stepped impedance ring resonators - Electronics Letters

Introduction: Emerging indoor geolocation systems use either geometric techniques [1, 2], or pattern recognition algorithms [3, 4] to locate a user. This is done in two stages. The first stage is to observe some characteristic of the transmitted signal, such as received signal strength (RSS), or delay (TOA) to derive location metrics. The second stage is to feed these metrics into a geolocation algorithm [1]. TOAbased systems use geometric methods, such as standard least-squares (LS) and the residual weighting LS (RWGH) algorithms. In this Letter we present a new algorithm for accurate indoor geolocation using TOA, and compare its performance quantitatively with the traditional LS and RWGH algorithms. There are many different approaches to LS algorithms; in this Letter, an LS algorithm developed by Davidon [5] has been used. The RWGH algorithm used, described in [6], is a form of weighted LS algorithm. It has been proposed as a method of mitigating the effects of range measurement errors resulting from obstructed line-of-sight (OLOS) channel conditions.