Statistical cellular Gaussian scatter density channel model employing a directional antenna for mobile environments

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.

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.

One of the fundamental research areas in wireless communications is the development of realistic models that can efficiently and accurately describe the wireless propagation channel. In multi-path environments, the received signal frequency constantly varies as a result of the relative motion between the receiver and transmitter. In this paper, we bridged a novel 3D geometric channel model and the multiple-input and multiple-output (MIMO) antenna array, analyzed deeply the probability density functions (PDFs) of the Doppler shift (DS), its variance, and characteristic function and etc. For the particular channel model, analytical expressions for PDFs of the channel model and the DS of mobile station (MS) due to its motion, have been derived. Based on the analysis, we investigated MIMO receiving performance. Also developed a geometric channel model, and was firstly in the asymmetric geometry literature due to a directional antenna array employed at base station. For this channel model, it was assumed that each multi-path component of the propagating signal undergoes one bounce. It was also assumed that the scattering objects around MS, could be expressed as Gaussian and exponential density models, which are more suitable to simulate outdoor and indoor environments.

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).

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.

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.

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.

Based on the joint estimations of time of arrival (TOA), angle of arrival (AOA) and angle of departure (AOD) of two or more single-bounced multipaths from a single base station (BS) and an mobile station (MS) in an MIMO system, two schemes, closed-form total least squares solution (CF-TLS) and constraint-based grid-search approach (CB-GSA) are presented to locate an MS. The CF-TLS method is time saving and provides good location accuracy when two or more resolvable single-bounced multipaths are available. However, the CB-GSA method always provides better location accuracy than the CF-TLS method at a cost of large computational burden. When only two single-bounced multipaths can be observed or the range and angle measurement errors are large, the location accuracy of the CB-GSA method outperforms that of the CF-TLS method significantly. By executing the CF-TLS method to give an initial estimation of an MS position, the search area of the CB-GSA method is narrowed, and the location time is significantly reduced. Simulations verify the effectiveness of the two proposed methods.

Wireless technology is expected to undergo considerable transformation because of the numerous services offered by 6G communication networks, which virtually entirely encompass every part of everyday life and use a variety of devices. Channel modeling is an essential factor in designing 6G communication networks. To meet the channel requirements of future 6G communication networks, it is crucial to measure the channel to consider path loss, multi-band, fading, blocking effect, multipath clustering, transmitter, and receiver moving speed/direction/time. The goal of this paper is to design and evaluate a 6G communication network in Banda Aceh City using a statistical channel model. The channel model is associated with environmental conditions such as rainfall and humidity. The method is then based on computer simulation using the NYUSIM simulator to complete the channel modeling using an operating frequency of 95 GHz with a bandwidth of 800 MHz. In the simulator, the designed 6G channel model is evaluated in both line-of-sight (LOS) and non-line-of-sight (NLOS) network environments. In addition, the designated network parameters, such as the coverage area, angle of arrival (AoA), angle of departure (AoD), and power delay profile (PDP), are simulated. The results, at AoA, the value of received power for LOS conditions ranges from -86 dBm to -101 dBm, while the value for NLOS conditions ranges from -91 dBm to -111 dBm. Under LOS conditions, the received power for AoD ranges from -86 dBm to -101 dBm, whereas under NLOS conditions, it ranges from -91 dBm to -111 dBm. In the omnidirectional PDP, the pathloss value for the LOS condition is 99.8 dB and the delay is 17.9 ns, while the pathloss value for the NLOS condition is 104.2 dB with a delay of 28.1 ns. For the directional PDP, the LOS condition yields a path loss of 106.4 dB and a delay of 2.9 ns, while the NLOS condition yields a path loss of 110.5 dB and a delay of 3 ns. Conclusions. The simulation indicated that the AoA, AoD, and PDP in terms of received power, pathloss, and propagation delay are in acceptable conditions for a 6G network in Banda Aceh City in the two observed environments. Therefore, it is conceivable to establish a 6G network in Banda Aceh City in the future.

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.

This paper presents outdoor field experimental results in the 28-GHz frequency band of a 5G radio access system where base stations (BSs) are installed on buildings to deploy a 5G trial area in the Tokyo Odaiba waterfront area. This is an early field trial assessment of key 5G features such as BS and mobile station (MS) beam tracking, being deployed in dense urban areas. In the trial area, a variety of key 5G technologies and conditions are evaluated such as BS and MS massive multiple-input multiple-output (MIMO) antennas, beamforming and tracking, use of the high 28-GHz frequency, the wide frequency bandwidth of 400 MHz, intra-baseband unit (BBU) hand over (HO), and a coverage area in a realistic urban deployment with four different trial courses. Experimental results show that throughput exceeding 1 Gbps is achieved in the experiment area, and approximately 200 Mbps is achieved at 500 m away from the BS. We confirm that beam tracking and intra-BBU HO operate effectively while compensating for high path loss in the 28-GHz band to achieve a coverage area of 500 m. On the other hand, line of sight (LoS) and Non-LoS conditions are critical to 5G performance in the 28-GHz band, and we find that 5G connections may drop behind trees, buildings, and/or under a footbridge. The trial results show that the downlink throughput exceeds 50 Mbps in 85%, 50%, 70%, and 33% of the four different trial courses, respectively.

Due to the bias of range measurements in non-line-of-sight (NLOS) environments, location schemes performances undergo a dramatical degradation. This paper proposes a set of methods that integrate all the available heterogeneous measurements, without identifying NLOS from line-of-sight (LOS) measurements, to achieve more accurate location estimation. The proposed hybrid schemes combine Radio Signal Strength (RSS) at the three best nodes, in terms of higher RSS measurements, and an angular beam around the angle of arrival (AOA) at the serving BS to give location estimation of the mobile station (MS). The proposed schemes mitigate the NLOS effect in two steps: in the first step, the weighted sum of the intersections between the three best RSS measures weighted circles and the AOA angular beam is derived. In the second step, a weighting location method that utilizes the geometrical feature of cell layout and the three selected RSS range measurements is applied. Simulation results show that the proposed methods can achieve better accuracy compared to the conventional schemes in [1].

We present a new method of defining spatio-temporal clusters using the geometric modeling approach, which simulates the phenomenon (clustered multi-ray arrivals) that has a geometric analog. As such, various clusters are given different shapes to scatterer distributions based on their logical appeal to certain radio environments. This classification methodology is based on the semi-geometrically based statistical model developed in the previous work. Subsequently, the analytical expression of the cluster power is derived using the proposed model. As a test case, we further give the expression of weightage of cluster power for a Gaussian scatterer density model, where scatterers have a normal distribution of the x- and y-coordinates measured from the position of the mobile station. We also study the effect of this weightage on the average received power at the base station when directive antennas are implemented at the receiver using computer simulation. Finally the probability distribution function of the weightage of the apparent-cluster power in a generalized rural area are analyzed by assuming that the distribution of the apparent clusters has an exponentially decaying function in the radial distance and a uniform function in azimuth.

Non-line-of-sight (NLOS) propagation degrades the performance of wireless location systems. Thus, developing algorithms that are robust to NLOS is of great importance. This paper introduces a new location technique that utilizes time of arrival (TOA) and angle of arrival (AOA) measurements. In the proposed method, we assume the signal from the mobile station reaches each base station via one dominant scatterer. By including the scatterer's coordinates as unknowns in a TOA/AOA-based cost function and imposing some equality and inequality constrains, the location of the mobile station (MS) is shown to significantly improve. The performance of the proposed algorithm is assessed and compared with that of existing algorithms through extensive simulations.

Directional antenna based node localization and reliable data collection mechanism using local sink for wireless sensor networks