Abstract In specific ultra-wideband (UWB) localization scenarios, conventional non-line-of-sight (NLOS) identification algorithm cannot detect other not-direct-path conditions. We proposed an adaptive method based on machine learning and artificial neural networks. Compared to the division of data sets, we verified advantages set partitioning by method. The performance NLOS recognition using di...

A positioning optimization technique for non-lineof-sight environment is presented based on weighted orthogonal polynomial fitting technique and singular value decomposition. First, non-line-of-sight errors in TOA measurements are mitigated using weighted orthogonal polynomial fitting technique and the true range between the measuring terminal and the mobile station is approximated. Then the st...

Deterministic channel models, such as the three-dimensional (3D) ray launching method, can yield wireless parameters. In non-line-of-sight (NLOS) propagation, outdoor 3D method that considers diffraction effects is more accurate than one does not. While considering effect, obtaining point challenging. This paper proposed a for determining diffracted rays using receiving sphere in launching. The...

This paper deals with the problem of radio localization of moving terminals (MTs) for indoor applications with mixed line-of-sight/non-line-of-sight (LOS/NLOS) conditions. To reduce false localizations, a grid-based Bayesian approach is proposed to jointly track the sequence of the positions and the sight conditions of the MT. This method is based on the assumption that both the MT position and...

In this paper, we analyze the impact of a friendly unmanned aerial vehicle (UAV) jammer on UAV communications in presence multiple eavesdroppers. We first present channel components determined by line-of-sight (LoS) probability between and ground device, introduce different fadings for LoS non-line-of-sight (NLoS) links. then derive secrecy transmission satisfying both constraints legitimate wi...

In this paper channel assignment in ad hoc network using by channel impulse response is described. The distribution of channel impulse response is appropriate for the estimation of two propagation components (LOS – Line-of-Sight, NLOS – NonLine-of-Sight). The Rician factor K, represents the type of distribution, namely LOS component has Rician distribution and NLOS component has Rayleigh distri...

This paper aims at investigating the achievable performance and the issues that arise in ultra-dense networks (UDNs), when the signal propagation includes both the Line-of-Sight (LOS) and Non-LineOf-Sight (NLOS) components. Backed by an analytical stochastic geometry-based model, we study the coverage, the Area Spectral Efficiency (ASE) and the energy efficiency of UDNs with LOS/NLOS propagatio...

Herein, results from measurements conducted by the University of Bristol are presented. The channel characteristics of Multiple Input Multiple Output (MIMO) indoor systems at 5.2 GHz are studied. Our investigation shows that the envelope of the channel for non-line-of-sight (NLOS) indoor situations are approximately Rayleigh distributed and consequently we focus on a statistical description of ...

The key objective of this work was to obtain a MIMO model for a Line of Sight (LOS) channel component as well as the covariance matrix for a Non LOS deployment. A Maximum Likelihood Criteria is applied to obtain a LOS Spatial Signature Vector and a NLOS Covariance Matrix derived from channel measurements taken in the 2GHz UMTS spectrum for an urban deployment in Bristol (UK). Different user equ...

Time-of-arrival (TOA) estimation is the first step of the most positioning algorithms. However in various environments especially when ultra wideband (UWB) pulses are used, TOA extraction from the received signal is challenging. UWB radio propagation bears multipath phenomenon, therefore correct identification of the first path TOA highly depends on the statistical characteristics of the enviro...