Hybrid mobile station location methods for single base station multiple-input multiple-output communication systems

A novel positioning scheme based on the specific communication network for high-speed train (HST) with a single base station (BS) is presented. In order to improve the accuracy of TOA estimation, the proposed method utilizes the cumulative sum of time-of-arrival (TOA) estimation values, which are measured during the initial ranging (IR) and periodical ranging (PR) process of each mobile station (MS). When the HST gets close to the BS, a positioning algorithm based on angle- of-arrival (AOA) estimation is employed to guarantee the accuracy of positioning. Simulation results are implemented under the mobile worldwide interoperability for microwave access (WiMax) configuration, showing that the proposed scheme dramatically improves the accuracy and reliability of TOA estimation. Furthermore, by using the combined scheme of TOA and AOA estimation, real-time and accurate location information could be provided for HST.

Integrated sensing and communication (ISAC) in the Industrial Internet of Things (IIoT) presents unique challenges in terms of localization techniques. While three-dimensional (3D) environments offer extra challenges to enhanced accuracy and realism, research in this area remains limited. To bridge this gap, we propose a novel localization technique assisted by a single base station (BS) in 3D IIoT scenarios. Our approach employs the MUltiple SIgnal Classification (MUSIC) algorithm to jointly estimate the angle of arrival (AoA) in azimuth and elevation, as well as the time of arrival (ToA). Compared to conventional multi-BS-assisted or MUSIC-based algorithms, our technique offers flexibility, easy implementation, and low computational cost. To improve performance, we integrate the Taylor-series into the iterative process after a MUSIC-based joint azimuth, elevation angle and delay estimation (JAEDE), resulting in a significant 99% reduction in computational complexity compared to a two-step MUSIC-based approach utilizing coarse-fine grid searching. Through numerical simulations, we compare our algorithm with three other MUSIC-based joint or separate estimation approaches, demonstrating its superior performance in azimuth angle of arrival (AoAz), elevation angle of arrival (AoAe), TOA, and overall location estimation across varying signal-to-noise ratio (SNR) conditions.

This paper introduces a novel simplistic geometrical disk scattering model in which the local scatterers are uniformly distributed in polar coordinates within a disk centered on the mobile station (MS). The proposed joint uniform distribution in polar coordinates results in a higher concentration of scatterers around the disk center and a lower concentration far from it. Furthermore, it is assumed that the base station (BS) is elevated to a non-scattering region and that a wave transmitted from the BS reaches the MS after a single bounce by one of the randomly distributed scatterers. Under the above-mentioned assumptions, we derive closed-form expressions for the joint probability density function (PDF) of the time-of-arrival (ToA) and angle-of-arrival (AoA), as well as for the joint PDF of the angle-of-departure (AoD) and AoA. From the joint distributions, we derive the marginal PDFs of the ToA, AoA, and AoD. Finally, we analyze the average delay and the delay spread of the proposed disk scattering model. The results presented in this paper enable the designers of cutting-edge mobile communication systems to study the system performance under simple, yet realistic, scattering conditions.

When there is non-line-of-sight (NLOS) path between the mobile station (MS) and base stations (BSs), it is possible to integrate many kinds of measurements to achieve more accurate measurements of the MS location. This paper proposed hybrid methods that utilize time of arrival (TOA) at five BSs and angle of arrival (AOA) information at the serving BS to determine the MS location in NLOS environments. The methods mitigate the NLOS effect simply by the weighted sum of the intersections between five TOA circles and the AOA line without requiring priori knowledge of NLOS error statistics. Simulation results show that the proposed methods always give superior performance than Taylor series algorithm (TSA) and the hybrid lines of position algorithm (HLOP).

Based on the results of an analysis of foreign publications of the last ten years in the field of device positioning in cognitive radio systems and networks of the fifth and sixth generations, we can state the emergence of a new scientific direction - personal radars. Their practical implementation became possible with the transition of transceivers to the range of millimeter and submillimeter waves, as well as due to the widespread use of multi-element antenna arrays both at base stations and on user devices. In mobile radio networks of the fourth and fifth generations, the problem of determining the location of user devices was solved centrally, predominantly using multi-position range and/or angle methods, when signals received or transmitted by several base stations served to collect primary measurements of signal time and/or angle of arrival/departure. In contrast to the centralized multi-position estimation of coordinates in existing com munication networks, the concept of a personal radar in promising sixth-generation cognitive radio systems with a device-centric architecture makes it possible to solve the problem of positioning a user device using a single-position method based on a signal from a singlebase station. The single-position method is based on the sparse property of a millimeter-wave radio channel, its representation in the beam space domain, as well as the use of a compressed sensing algorithm in space based on a set of departure and arrival angles. This work is devoted to the development of mathematical and simulation models to establish the accuracy limits and conditions for the practical feasibility of a single-position method for estimating the coordinates and orientation of user devices based on a signal from a single base station in sixth-generation cognitive radio systems operating on the principle of a personal radar. The presented mathematical formalization and software implementation of the single-position positioning method showed its performance on a plane when estimating the coordinates and orientation of the device with an accuracy of up to units of meters and units of degrees.

In this paper, a hybrid multi-user massive MIMO system operating on the mmWave frequency is considered. To reduce the heavy beam training overhead for such a massive MIMO system, we propose a 3D beam training algorithm, which estimates the azimuth and elevation of the angle of arrival (AoA) and departure (AoD) between the base station (BS) and the mobile stations (MSs). The proposed algorithm first executes a hierarchical search to acquire the range of azimuth and elevation, then applies an exhaustive search within this range for a more precise matching. Through this two-stage approach, the beam training overhead can be substantially reduced.

In this paper, a generalized 3-D scattering model is presented for macrocellular land mobile radio cellular systems with a mobile station (MS) located at the center of a 3-D scattering semispheroid and a base station (BS) employing a directional antenna located outside of the semispheroid. The effect of the directional antenna is thoroughly observed on spatial and temporal characteristics of the proposed model. Closed-form expressions for joint and marginal probability density functions (pdf's) of the angle of arrival (AoA) seen at the MS and the BS in correspondence with azimuth and elevation angles are derived. Furthermore, closed-form expressions for propagation path delays and trivariate joint pdf's of the time of arrival (ToA) seen at the MS and the BS in correspondence with azimuth and elevation angles are derived. Moreover, the theoretical results, along with observations, are shown that illustrate the effect of the directional antenna on the spatiotemporal statistics of the proposed 3-D model. The proposed 3-D scattering model is shown to deduce all previously proposed 2-D and 3-D models that assume a uniform distribution of scatters with directional or omnidirectional antennas found in the literature for a macrocell environment. The obtained theoretical results are compared with some notable 2-D and 3-D scattering models to validate the generalization of the proposed model.

Location estimation in wireless communications systems experiencing purely non-line-of-sight propagation paths is an open problem. In this paper, a novel least squares algorithm is presented to estimate the location of a mobile station (MS) experiencing purely non-line-of-sight communication with at least one base station (BS) by using the time of arrival (TOA), angle of arrival (AOA), and Doppler-shift (DS) measurements collected at the BS. Simulation results are provided to demonstrate the estimation accuracy and improvement over existing methods.

Accurate precise positioning at millimeter wave frequencies is possible due to the large available bandwidth that permits precise on-the-fly time of flight measurements using conventional air interface standards. In addition, narrow antenna beamwidths may be used to determine the angles of arrival and departure of the multipath components between the base station and mobile users. By combining accurate temporal and angular information of multipath components with a 3-D map of the environment (that may be built by each user or downloaded a-priori), robust localization is possible, even in non-line-of-sight environments. In this work, we develop an accurate 3-D ray tracer for an indoor office environment and demonstrate how the fusion of angle of departure and time of flight information in concert with a 3-D map of a typical large office environment provides a mean accuracy of 12.6 cm in line-of- sight and 16.3 cm in non-line-of-sight, over 100 receiver distances ranging from 1.5 m to 24.5 m using a single base station. We show how increasing the number of base stations improves the average non-line-of-sight position location accuracy to 5.5 cm at 21 locations with a maximum propagation distance of 24.5 m.

In this paper, a propagation model is presented for the land mobile radio cellular systems with 3-D Gaussian distributed scatterers around Mobile Station (MS). The Base Station (BS) equipped with a directional antenna is located outside of the scattering region. The effect of directional antenna is thoroughly observed on spatial and temporal characteristics of the proposed model. General expressions for joint and marginal probability density functions (PDFs) of Angle-of-Arrival (AoA) observed at MS and BS in correspondence with azimuth and elevation angles are derived. Novel expressions for the trivariate and the bivariate density functions for Time-of-Arrival (ToA) / AoA in correspondence with azimuth and elevation angles are derived. Exploiting the proposed model, the theoretical results along with observations are presented to illustrate the effect of directional antenna on the spatio-temporal characteristics of channel. Obtained theoretical results for spatial statistics at BS are compared with an empirical set of measured data, which also demonstrates the validity of proposed model.

Millimeter-wave (mmWave) bands is considered for fifth-generation (5G) cellular systems because abundant spectrum is available for mobile broadband communications. In mmWave communication systems, accurate beamforming is important to compensate for high attenuation in the mmWave frequency band and to extend the transmission range. However, with the existing beamformers in mmWave cellular systems, the mobile station (MS) cannot identify the source (base station; BS) of the received beam because there are many neighboring BSs transmitting their training signals, requiring a large overhead. This paper proposes a new beam weight generation method for transmitting (Tx) beamformers at the BS in mmWave cellular systems during a beam training period. Beam weights are generated for Tx beamformers at neighboring BSs, so that a mobile station (MS) can estimate the source (cell ID; CID) and angle of departure (AoD) for each BS in multi-cell environments. A CID and AoD estimation method for mmWave cellular systems in a line-of-sight (LOS) dominant condition is presented using the beam weights generated by Zadoff-Chu sequence. A simulation is conducted in a LOS dominant condition to show that the performances of CID detection and AoD estimation are similar for both the proposed and conventional methods. In the conventional methods, the DFT-based beamforming weight is used for Tx beamformer at the BS and orthogonal matching pursuit (OMP) algorithm is used for AoD estimation at the MS. The proposed method significantly reduces the processing time (1.6–6.25%) required for beam training compared to the conventional method.

In most textbooks on principles of automatic control, very limited content is given on the angles of arrival or departure from breakaway points of root loci. Sometimes, for simplicity of description, the angles of arrival or departure from breakaway points are given by $180^{\circ}/ l$ apart, where l denotes the number of branches of root loci that meet at the breakaway point; however, no detailed proof is given for this result. In this paper, detailed proof is provided for the angles apart of the root loci branches from the breakaway point. It is proved that, the result is valid with strictly positive real open loop transfer function in both cases of unit negative feedback and unit positive feedback. The proof is based on the property of angles of departure or arrival and the angle condition of the root locus itself. Several examples are given to support the proposed proof. The proposed results can be lectured to students for better understanding and more precise plot of root locus.

This paper proposes a new localization algorithm to locate the targets in non-line-of-sight (NLOS) environment by maneuverable single station. The algorithm first estimates scatters’ positions in the second layer and the distances from the second-layer scatters to the mobile station (MS) based on the circular motion characteristics. Second, by selecting the second-layer scatters as the virtual base station (BS), we can convert the problem of single station localization into the one with multiple stations. Third, the time difference of arrival (TDOA) algorithm is used to estimate the positions of the first-layer scatters. Finally, we will use the positions of the first-layer scatters and the angle of departure (AOD) to estimate the real positions of MS. The efficiency of our proposed algorithm is verified based on the simulation in a simple two-layer scattering model.

An analytical space-time fading correlation for the multi-input-multi-output (MIMO) channel, as a function of antenna spacing, angle spread, and Doppler spread, is derived and is verified with deterministic simulations. We investigate the performance of the uplink spatial fading correlation of a MIMO channel. We consider four uniform circular array (UCA) elements at both mobile station and base station. The angle of arrival and the angle of departure at the base station and the mobile station are distributed by truncated Gaussian and uniform probability distribution function(s) respectively. For large values of N, the simulation and analytical results agree. The results show that spatial separation between antenna elements can be minimized at the base station by employing two or more antennas at the mobile station

This article proposes geometrically-based stochastic channel model with scatterers homogeneously distributed within $N$ -dimensional ( $N$ -D) hyperspherical-shaped scattering region for single-bounce propagation scenario, with arbitrary positions of base station (BS) and mobile station (MS). For such defined geometrically-based stochastic channel model, the angular and temporal statistics are determined by introducing the projective approach. Accordingly, azimuthal angle and time of arrival marginal PDFs are derived in closed form, while the elevation angle PDF can be delivered numerically in general, and in closed-form for specific environmental parameters. The fidelity of the analytically obtained results is evaluated by their comparison to the corresponding normalized histograms. Also, it is shown that the proposed $N$ -D model can be used to analyze some of the existing channel models like 2-D uniform disk and 3-D uniform (hemi)sphere models. Additionally, by introducing the mentioned projective approach, it is shown that the angular statistics of the proposed $N$ -D model are the same as the angular statistics of some nonuniform 2-D and 3-D models, which is an important property of the proposed model. Such observation enabled us, for the first time in the literature, to determinate angular statistics for geometrically-based stochastic channel models such as inverted parabolic scattering model, 2-D Gaussian model and 3-D Gaussian hemisphere model, for arbitrary positions of BS and MS. Such angular characteristics of proposed channel model are validated through several empirical datasets.