Time evolutionary wideband propagation channel model for user positioning in UMTS

Dilution of precision (DOP) for time-of-arrival (TOA) or time-difference-of-arrival (TDOA) positioning systems has been thoroughly investigated. This is not the case for angle-of-arrival (AOA) positioning systems, especially three dimensional AOA systems. However, the recent increase in deployment of antenna arrays and multipath mitigation techniques make AOA systems more attractive. In this paper, the DOPs for position systems using range measurements are reviewed and an expression for 3D AOA DOP is derived. The average values of DOPs for different deployments of base station geometries are examined. It is found that for a 3D AOA system, unlike TOA or TDOA systems, vertical DOP (VDOP) is generally smaller than horizontal DOP (HDOP), and the best VDOP can be achieved when the base stations are at the same height as the user. Moving the base stations away from the plane of the user may decrease the HDOP and Geometric DOP (GDOP) slightly, but it also increases the VDOP. For applications that the height of the user changes frequently, the base stations should be deployed with height close to half the height of the area of interest.

This study develops a hybrid positioning scheme that combines both differential time of arrival (DTOA) and angle of arrival (AOA) observations of the 1090-MHz automatic dependent surveillance-broadcast (ADS-B) signal and implements it on a wide area multilateration (WAM) test bed. The major issue when combining DTOA and AOA observations is synchronization. A synchronization design for DTOA and AOA observations is thus evaluated. The positioning algorithm that combines AOA and DTOA observations is a filter-based approach. Based on the measurement errors from actual ADS-B signals received from real flights, simulation is used to evaluate the positioning performance of the proposed 1090-MHz ADS-B WAM with the integration of AOA/DTOA approach under two scenarios, namely DTOA alone and AOA combined with DTOA.

This paper presents an ultra wideband (UWB) channel sounding scheme with a technique for time of arrival (TOA) and angle of arrival (AOA) estimation using transformation between time and frequency domain signals. Since the measured UWB power spectrum can be transformed into a time domain signal, both frequency and time domain signals are available for the channel estimation. We propose the TOA estimation using a peak search over time domain signal, and the AOA estimation using MUSIC and AOA histograms. The AOA histogram is counted for AOA samples of discrete frequencies over the UWB bandwidth. Comparing both AOA histograms before and after TOA subtraction, we can determine pairing the elements of TOA vector and those of AOA vector. The anechoic chamber tests indicated that both TOAs and AOAs were precisely resolved for two-path model, even if either TOAs or AOAs were too close to resolve.

Global Navigation Satellite System (GNSS) has been widely used in people’s life. Generally, GNSS signals suffer from severe attenuation in urban canyon environments. the 5th generation wireless systems (5G) and GNSS hybrid positioning technique is a promising localization technique because 5G base stations are able to help GNSS relieve the problem of lacking visible satellites in urban environments. However, 5G-GNSS hybrid positioning faces the time synchronization problem. The conventional methods based on time of arrival (TOA) or time difference of arrival (TDOA) require that the time synchronization accuracy between two base stations should at least be 30-nanosecond level to make sure the range error is below 10 m, which is difficult to achieve in real applications. This work proposes a 5G-GNSS hybrid positioning scheme basing on AOA-TOA measurements. We combine the angle of arrival (AOA) estimates from 5G base stations and TOA measurements from GNSS satellites to perform hybrid localization. Moving averaging operation is then performed on the raw position estimates to further reduce the effect of noise. The principle of the proposed algorithm is explained detailedly. Numerical results demonstrate that the proposed method can be free from the influence of the time synchronization error, thus it improves the accuracy and robustness of hybrid positioning system in comparison with conventional methods.

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).

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.

Localization of autonomous underwater vehicles (AUVs) is a very important and challenging task for the AUVs applications. In long baseline underwater acoustic localization networks, the accuracy of single-way range measurements is the key factor for the precision of localization of AUVs, whether it is based on the way of time of arrival (TOA), time difference of arrival (TDOA), or angle of arrival (AOA). The single-way range measurements do not depend on water quality and can be taken from long distances; however, there are some limitations which exist in these measurements, such as the disturbance of the unknown current velocity and the outliers caused by sensors and errors of algorithm. To deal with these problems, an AUV self-localization algorithm based on particle swarm optimization (PSO) of outliers elimination is proposed, which improves the performance of angle of arrival (AOA) localization algorithm by taking account of effects of the current on the positioning accuracy and eliminating possible outliers during the localization process. Some simulation experiments are carried out to illustrate the performance of the proposed method compared with another localization algorithm.

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.

In this thesis, we cope with the fundamental mathematical and physical problems of the space-time-Doppler UWB system design for fading channels: multi-input multi-output (MIMO) wireless communication with adaptive filtering. The estimation algorithm from equalizer providing an accurate parameters estimate is investigated. UWB radio is a fast emerging technology with uniquely attractively features inviting major advances in wireless communications, networking, radar, imaging, and positioning systems. By its rule-making proposal in 2002, the Federal Communications Commission (FCC) in the United States essentially unleashed huge new bandwidth (3.6-10.6 GHz) at the noise floor, where UWB radios overlaying coexistence RF systems cerate using low-power ultra-short information bearing pulses. Right now, there are three basic types of UWB: multiband OFDM UWB (MB-OFDM UWB), impulse-UWB (I-UWB), and direct sequence UWB (DS-UWB). We focus on I-UWB and MB-OFDM-UWB, and compare their performance. A simple means for spreading the spectrum of low duty cycle pulse trains is time hopping (TH), with pulse position modulation (PPM) for data modulation at the rate of many pulses per data bit. The main contribution of this thesis for I-UWB is the design of leading edge detectors, coherent correlation detector (CCD), and pilot performance enhancement compared with different Rayleigh and Ricean fading conditions. For MB-OFDM UWB, we have considered the performance analysis and design criteria of MIMO OFDM UWB systems for high data-rate wireless transmission. The signal processing of frame detection, time synchronization, frequency synchronization, channel estimation, synchronization tracking using pilot subcarriers and 2-D MIMO detection algorithms is discussed. The main contributions of this thesis are 1) Compared with receiver employing the Maximum Likelihood (ML) detector, the receiver employing a low-complexity linear Minimum Mean Square Error (MMSE) demodulator can perform a limited performance loss in spatially uncorrelated channels. 2) Due to the operations of spreading and dispreading combined with MMSE-based frequency domain equalization, the adverse effects of the low-SNR subcarriers on the average BER performance are potentially improved. This is a direct consequence of spreading, because even if the signal corresponding to a specific chip is obliterated by a deep frequency domain channel fade, after dispreading these effects are spread over the Walsh-Hadamard Transform (WHT) length. Hence there is a high chance of still recovering all the partially affected subcarrier symbols without errors. 3) As a test case, the OFDM-based 200 Mb/s MB-UWB network (IEEE 802.15.3a) are considered, but the simulation results are shown above section. 4) The simulation channel can be easily applied to NOS and NLOS situation with WHT transformation from Simulink model. The fading channels of UWB with low/high signal to noise ratio (SNR), multipath effects, and multiuser interference may introduce large errors in location. The location engine performs the following tasks: █ Data fusion techniques: Different data fusion techniques are implemented using Time Of Arrival (TOA), Angle Of Arrival (AOA), or a combination of both. █ Channel modeling: A multipath, multiuser channel environment is created that models path loss, shadowing, Rayleigh fading, and Doppler frequency effects. █ Parameter estimation: TOA and AOA estimation algorithms are implemented as part of the location finding engine. Different variations of algorithms are implemented for performance and comparison purposes. █ Configuring the physical layer for different wireless networks. Among the programmable parameters are spreading factor, packet size, training length, constellation type, modulation technique, carrier frequency, level of transmitted signal power, and the number of antennas at the transmitter for both sides. █ Configuring the mobile user conditions. The wireless channel models depend on the Doppler frequencies present in the environment. The Doppler frequency depends on the mobile speed and carrier frequencies as input and generates a Rayleigh fading channel with the U-shape Doppler spectrum. █ Configuring the environmental parameters and network geographical structure. One of the factors affecting the performance of the wireless location system is the environment type (e.g., bad urban, urban, suburban, or rural area). For example, in a bad urban area with many blocking objects and buildings, non-line of sight (NLOS) effects plays an important role in the estimation accuracy.

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.

Global navigation satellite system (GNSS) has been widely used in many fields due to their low cost and high positioning accuracy. Because of the open frequency of navigation signals, the low power of navigation signals, and the growing reliance of many modern wireless systems on satellite-based navigation, GNSS performance may be easily affected by interference signals. Monitoring and troubleshooting of interference sources are important means to guarantee the normal use of satellite navigation applications and are an important part of GNSS operation in complex electromagnetic environments; however, traditional angle of arrival (AOA) algorithms cannot efficiently operate with coherent signals, so a decoherence-based orientation scheme is proposed to optimize the AOA algorithm. Furthermore, a joint AOA and time difference of arrival (TDOA) interference localization algorithm is proposed for problems such as the lack of accuracy in a single interference source localization algorithm. Numerical simulation results show that decoherence-based AOA localization can be well applied to various interference signals, and the accuracy of the joint AOA and TDOA interference localization algorithm is higher than that of single-method interference localization. In addition, the physical verification further verifies the usability and reliability of the GNSS interference source positioning algorithm proposed in this paper.

We develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival (AOA) of the multipath components, which are required to test adaptive array algorithms for cellular applications. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This geometrically based single bounce macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the AOA of the components. Using the GBSBM model, we analyze the effect of directional antennas at the base station on the fading envelopes. The level crossing rate of the fading envelope is reduced and the envelope correlation increases significantly if a directional antenna is employed at the base station.

A novel hybrid wireless positioning method in non-line of sight (NLOS) situation is proposed in this paper. Firstly, a Kalman filter (KF) is used to track the NLOS bias in the time of arrival (TOA) measurements so as to mitigate the NLOS error. Secondly, another KF combines the most three common positioning methods, the time difference of arrival (TDOA) positioning, the TOA positioning and the angle of arrival (AOA) positioning, to achieve high location accuracy. Bused on linear forms of the measurement equations, the location estimator that use the linear KF (LKF) rather than the extended KF (EKF) is developed, thus the computation can be simplified. Simulation shows that the proposed hybrid method gives good performance.

EToA: New 2D geolocation-based handover decision technique

This paper presents a geometrically based statistical channel model with scatterers that are randomly distributed around the base station within a circle that is determined by the coverage area of the base-station antenna. The joint probability density function (pdf) of time of arrival (TOA)/angle of arrival (AOA), the marginal pdf of AOA, and the marginal pdf of TOA are derived for a general distribution of scatterers around the base station. Rayleigh and exponential distributions are selected as special cases for discussion. Comparisons between our theoretical calculations and the empirical results, as well as the measurement data that are reported in the literature, show that the Rayleigh distribution scatterer model can be applied to an outdoor microcell propagation environment, while the exponential distribution scatterer model gives accurate results for an indoor office/laboratory propagation environment.