In this paper, we investigate the non-line-of-sight (NLOS) propagation identification and correction for time difference of arrival (TDOA) based mobile user location in wireless communication systems. Based on the defined TDOA residual, an NLOS base station identification algorithm is proposed. Different choices of the reference location for the residual calculation are compared via simulation....

Accurate characterization of spatial multipath channels at millimeter wave bands has gained significant interest both in industry and academia. A channel measurement was conducted at three different frequency bands, i.e., 2− 4, 14− 16, and 28− 30 GHz in a line-of-sight (LOS) and an obstructed-LOS (O-LOS) scenarios in an empty room environment. A vector network analyzer connected to a virtual un...

Young stars are surrounded by copious amounts of circumstellar material. Its composition, in particular its gas-to-dust ratio, is an important parameter. However, measuring this ratio is challenging, because gas mass estimates are often model dependent. X-ray absorption is sensitive to the gas along the line-of-sight while optical/near-IR extinction depends on the dust. Therefore, the absorber’...

Localization is one of the key techniques in wireless sensor network. The location estimation methods can be classified into target/source localization and node self-localization. In target localization, we mainly introduce the energy-based method. Then we investigate the node self-localization methods. Since the widespread adoption of the wireless sensor network, the localization methods are d...

-Whenever a mobile robot has to deal with an environment that is totally or partially unknown or dynamically changing, local navigation strategies are very important for the robot to successfully achieve its goals. Unfortunately, local navigation algorithms that have been proposed in the literature offer poor performance (or even fail) whenever the geometry of the free space in which the robot ...

There are many possible observing strategies available for mapping the thermospheric wind field by using observations of the Doppler shift of the 0 (‘D) airglow with a Fabry-Perot interferometer. The determination of the neutral wind field from observed line-of-sight velocities invariably involves some assumptions about the nature of the wind field. A standard method of observing employs the as...

Wireless sensor networks deployed within metallic cavities are known to suffer from a very severe fading, even in strong line-of-sight propagation conditions. This behavior is well-captured by the Two-Wave with Diffuse Power (TWDP) fading distribution, which shows great fit to field measurements in such scenarios. In this paper, we address the joint estimation of the parameters K and Δ that cha...

Gravitational lensing of an optical QSO by a spiral galaxy is often counteracted by dust obscuration, since the line-of-sight to the QSO passes close to the center of the galactic disk. The dust in the lens is likely to be correlated with neutral hydrogen, which in turn should leave a Lyα absorption signature on the QSO spectrum. We use the estimated dust-to-gas ratio of the Milky–Way galaxy as...

IEEE 802.15.4a networks can provide the geographic routing solution with high location accuracy for the indoor environments. However, in the non-line-of-sight (NLOS) environments, the IEEE 802.15.4a networks may have a large scale location error and an unstable communication link. In this article, we propose a location estimation and dynamic link detection scheme for the geographic routing in t...

We have investigated the dependence of the wavelength shift of the coronal emission line profiles on the line of sight velocity of the emitting plasma. The results of our numerical calculations point out that, while the wavelength shift of the collisionally excited component of the line is related to the line of sight velocity by the usual formula for the Doppler effect, that of the resonantly ...