Performance bounds for multipath-assisted indoor navigation and tracking (MINT)

Abstract

The MINT (multipath-assisted indoor navigation and tracking) problem exploits the geometry of deterministic multipath components (MPCs) for robust indoor positioning in line-of-sight (LOS) and non-LOS situations. It assumes a known room layout and can thus easily make use of signals reflected by the walls, for instance. In this paper, the Cramér-Rao lower bound of the positioning error is derived for this problem. This requires a novel channel model, where diffuse multipath is modeled as a colored Gaussian process that influences the effective SNR of deterministic MPCs. The adverse effect of path overlap is demonstrated and discussed. Computational results show the three-fold importance of a large signal bandwidth. The bandwidth reciprocal (i.e. the pulse duration) multiplies the error standard deviation-a fundamental result well-known from AWGN channels. But it also multiplies the effective power of the interfering diffuse multipath and gives rise to additional path overlap. A minimum bandwidth of 1 GHz seems appropriate and sufficient.

Cognitive radar for the localization of RFID transponders in dense multipath environments

“…Firm insight is thus provided how to employ the CR for efficiently and robustly estimating the target locations. Evaluating (2), it has been found in [8], [15] that bandwidths of at least 1 GHz are needed to achieve satisfying positioning performance in dense indoor channels.…”

“…Time reversal (TR) processing [5], [6] is proposed, which is expected to be beneficial to overcome the degenerate pinhole channel of a backscatter radio system [7]. At the receiver side, deterministic MPCs can aid the target localization problem and overcome non-line-of-sight (NLOS) situations [8]. An RX-side environment model that is also learned at runtime provides the required channel information.…”

“…The environment model also provides the weightsŵ 2 k (p), which quantify the power of diffuse multipath interfering with the k-th deterministic component (cf. Section II-B and [8]). The path gains {α…”

“…[13]), a rank-one matrix with an eigenvector in direction of φ k . "Interference" has been modeled as a Gaussian random process representing diffuse multipath [8]. Its effective power is T s S ν (τ k ), the product of an effective pulse duration T s and the power delay profile S ν (τ k ) for the diffuse multipath at delay τ k .…”

“…The transmitted pulse p(t) is modeled as root-raised cosine pulse, with a rolloff factor of β roll = 0.6 and a pulse duration of T p = 0.5 ns. The carrier frequency f c of the pulse is 7 GHz and similar to [8], we used a free-space path-loss model for the MPC gains. The diffuse part of one single channel is modeled as doubleexponential function cf.…”