3D Geometry-based Stochastic Model Research Articles

A Wideband Non-Stationary 3D GBSM for HAP-MIMO Communication Systems at Millimeter-Wave Bands

High-altitude platforms (HAPs) are considered to be the most important equipment for next-generation wireless communication technologies. In this paper, we investigate the channel characteristics under the configurations of massive multiple-input multiple-output (MIMO) space and large bandwidth at millimeter-wave (mmWave) bands, along with the moving essence of the HAP and ground terminals. A non-stationary three-dimensional (3D) geometry-based stochastic model (GBSM) is proposed for a HAP communication system. We use a cylinder-based geometric modeling method to construct the channel and derive the channel impulse response (CIR). Additionally, the birth–death process of the scatterers is enclosed using the Markov process. Large-scale parameters such as free space loss and rainfall attenuation are also taken into consideration. Due to the relative motion between HAP and ground terminals, the massive MIMO space, and the wide bandwidth in the mmWave band, the channel characteristics of HAP exhibit non-stationarities in time, space, and frequency domains. By deriving the temporal auto-correlation function (ACF), we explore the non-stationarity in the time domain and the impact of various parameters on the correlations across the HAP-MIMO channels. The spatial cross-correlation function (CCF) for massive MIMO scenarios, and the frequency correlation function (FCF) in the mmWave bands are also considered. Moreover, we conduct simulation research using MATLAB. Simulation results show that the theoretical results align well with the simulation results, and this highlights the fact that the constructed 3D GBSM can characterize the non-stationary characteristics of HAP-MIMO channels across the time, space, and frequency domains.

A 3D MIMO Channel Model for a High-Speed Train Millimeter Wave Communication System under Cutting and Viaduct Environments

Incorporating MIMO technology with 3D geometry-based stochastic models (GBSM) is a promising channel modeling technique for 5G and beyond. These models could be extended to high-speed train (HST) environments at mmWave bands. In this paper, the proposed 3D MIMO model is composed of the line of sight component (LOS), the non-line of sight component (NLOS) from one sphere, and multiple stochastic confocal elliptic cylinders. The model is applied in the viaduct and cutting environments with a time-varying Rician K-factor. The local channel statistical properties such as the auto correlation function, stationarity distance, and the level crossing rate (LCR) are derived and thoroughly investigated at the 41GHz frequency. These properties are compared with the corresponding measured results at the same wave frequency for an HST wireless channel. There is a strong correlation between the results from the derived model and the measured results. Therefore, this model can be extended to be used for viaduct and cutting channel modeling at the mmWave band.

Impact of UAV Rotation on MIMO Channel Characterization for Air-to-Ground Communication Systems

Unmanned aerial vehicle (UAV) communications have been considered as one of the promising technologies to support numerous applications in the fifth and sixth generations wireless networks. A deep understanding of propagation channel is necessary for the design of wireless communication systems. A three-dimensional (3D) wideband non-stationary geometry-based stochastic model (GBSM) is proposed for UAV multiple-input multiple-output (MIMO) channels in this paper. The proposed GBSM considers the both line-of-sight (LoS) and non-LoS (NLoS) components in the transmission links from a UAV transmitter (Tx) to a ground receiver (Rx), the proposed 3D GBSM is used for the first time to investigate the impact of UAV rotation, which results in time-varying channel parameters and reflects the non-stationarity of channel. Based on the proposed model, we derive and study some significant statistical properties, including the transfer function, space-time-frequency correlation function, Doppler power spectrum, and quasi-stationary interval. Numerical results show that the UAV rotation has a significant impact on channel statistical properties and non-stationarity. It is found that, even for a low range of UAV rotations, channel correlations are significantly affected, and the time correlation gradually increases with the pitch angle of UAV. Finally, the impact of using directional antennas at Tx on channel characteristics is analyzed. It is found that the channel correlation with directional antenna is significantly increased compared with the results with omnidirectional antenna. These observations and conclusions can be used as a reference for the system design and performance analysis of UAV-MIMO communication systems.

Envelope Level Crossing Rate and Average Fade Duration of a Generic 3D Non-Stationary UAV Channel Model

For the unmanned aerial vehicle (UAV) communication scenarios, the time-varying fading characteristics cased by the three-dimensional(3D) scattering environment and 3D trajectory have an important impact on establishing the reliable communication link. In this paper, a generic 3D non-stationary geometry-based stochastic model (GBSM) for UAV channels is developed. Different from the traditional 3D GBSMs, the proposed model takes the 3D arbitrary trajectories of UAV into account. On this basis, two important second-order statistical properties of fading envelope, i.e., the level crossing rate (LCR) and average fading duration (AFD), are investigated and derived in details. The obtained closed-form expressions are explicit functions of flight parameters and compatible with the results in the previous works. Numerical simulations show that the simulated results are in accordance with the theoretical and measurement data under 3D flight scenarios. The proposed model and statistical properties can be applied to the optimal design of channel coding and block interleave schemes for UAV communication systems.

Air-to-ground 3D channel modeling for UAV based on Gauss-Markov mobile model

Air-to-ground (A2G) communication has been attracted great attention due to the gradual popularization of unmanned aerial vehicle (UAV). In this paper, a 3D geometry-based stochastic model (GBSM) for A2G channels is proposed. Meanwhile, the Gauss-Markov mobile model is adopted to generate dynamic trajectories. According to different scattering environments, we establish a reference model and a statistical simulation model for A2G channels, and derive their respective time correlation functions. In particular, the purpose of establishing the statistical simulation model is to reduce complexity, and we verify the consistency of the two models. Then, we analyze the dynamic motion scenarios generated by Gauss-Markov process, and their effects on A2G channel correlation. Finally, the good conformities of time correlation curves with the existing measurement data and sphere model verify the reliability of our proposed models.

Three‐dimensional non‐stationary geometry‐based stochastic model for UAV‐MIMO Ricean fading channels

In this study, the authors propose a novel three-dimensional (3D) non-stationary geometry-based stochastic model (GBSM) and the corresponding deterministic and stochastic simulation models for non-isotropic unmanned aerial vehicle (UAV) multiple-input multiple-output (MIMO) Ricean fading channels. The proposed GBSM employs a two-cylinder model, where the signal is a superposition of line-of-sight component, single-bounced rays around the UAV, single-bounced rays around the ground station (GS), single-bounced rays on the ground, and double-bounced rays. The non-stationarity is reflected on the time-varying angles of departure and angles of arrival. Since the authors consider the GS to be mobile, the proposed 3D GBSM is general and suitable for UAV-aided vehicular communication scenarios. Based on the proposed model, some important channel statistical properties are derived and thoroughly investigated, including the space-time correlation function, Doppler power spectral density, envelope level crossing rate and average fade duration. Moreover, the proposed model has the ability to investigate the influence of some unique UAV-related parameters on channel characteristics and non-stationarity. Finally, excellent agreement is achieved between the reference model and simulation models, demonstrating the feasibility of simulation models as well as the correctness of theoretical derivations.

A 3D Non-Stationary Channel Model with Moving Mobile Station in Rectangular Tunnel

This paper presents a three-dimensional (3D) geometry-based stochastic model (GBSM) for capturing the non-stationarity of radio channel at 1.8 GHz in a rectangular tunnel. A time-variant (TV) complex channel gain is derived for obtaining the statistical properties in time, frequency, and spatial domains such as the time-variant autocorrelation function (TV-ACF), the time-variant Doppler power spectral density (TV-DPSD), and the time-variant spatial cross-correlation function (TV-CCF), respectively. Then the TV channel statistical properties at different time instants can be extracted and the non-stationary channel characteristics caused by the TV scattering environment are thoroughly discussed. Furthermore, three cases including “approach”, “arrival”, and “away” are set to allow a comprehensive study on how the DPSD behaves with the relative position between transmitter and receiver. The reliability of proposed 3D GBSM is highlighted by a good agreement with the measured result in terms of the correlation function.

3D Non-Stationary Wideband Tunnel Channel Models for 5G High-Speed Train Wireless Communications

High-speed train (HST) communications in tunnels have attracted more and more research interests recently, especially within the framework of the fifth generation (5G) wireless networks. In this paper, based on cuboid-shape, three-dimensional (3D) non-stationary wideband geometry-based stochastic models (GBSMs) for HST tunnel scenarios are proposed. By considering the influence of the tunnel walls, a theoretical channel model is first established, which assumes clusters with an infinite number of scatterers randomly distributed on the tunnel walls. The corresponding simulation model is then developed and the method of equal areas is employed to obtain the discrete parameters, such as the azimuth and elevation angles. We derive and investigate the most important channel statistical properties of the proposed 3D GBSMs, including the time-variant autocorrelation function, spatial cross-correlation function, and Doppler power spectrum density. It is indicated that all statistical properties of the simulation model, verified by simulation results, can match very well with those of the theoretical model. Furthermore, a validation is presented by comparing the stationary regions of our proposed tunnel channel model to those of relevant measurement data.

Channel Modeling for Satellite Communication Channels at Q-Band in High Latitude

This paper proposes a three-dimensional (3D) channel model for satellite communications at Q-band in a high latitude, including the path loss, shadowing, and small-scale fading. The shadowing effect is modelled by a Markov chain. The three states in the Markov chain are separated by the threshold of the received power level for the link budget and system optimization. The probability density function (PDF) of shadowing amplitude is modelled by a mixture of two Gaussian distributions with parameters obtained by the expectation-maximum (EM) algorithm. The small-scale fading is represented by a 3D geometry-based stochastic model (GBSM) where scatterers are located on the spherical surface of a hemisphere. The movement of the receiver and the Rician factor influenced by environment scattering are considered. Statistical properties including the local temporal autocorrelation function (ACF) and Wigner-Ville spectrum are derived. The satellite communication channel measurement at Q-band is conducted on the campus of Heriot-Watt University (HWU) in Edinburgh, UK. The parameters of our proposed channel model are estimated by the measurement data. Numerical and simulation results demonstrate that our proposed channel model has the ability to reproduce main statistical properties which are also consistent well with the corresponding theoretical and measurement results.

A novel 3D GBSM for mmWave MIMO channels

In this paper, a novel three dimensional (3D) wideband geometry-based stochastic model (GBSM) for millimeter wave (mmWave) multiple-input multiple-output (MIMO) channels is proposed. A homogeneous Poisson point process (PPP) is used to generate the clusters in 3D space. The transmitter (Tx) and receiver (Rx) are surrounded by two spheres. The scatterers distributed in the two spheres are introduced to mimic the clustering effects of multipath components (MPCs) in delay and angular domains. The large-scale path loss model and line-of-sight (LOS) probability model are taken into account to make the channel model realistic. In addition, mmWave channel measurements are conducted in an indoor environment. Simulation results based on the two-sphere channel model are compared with measurement results and good agreements are achieved, which validates the proposed channel model. The results indicate that the proposed channel model has good adaptivity and can model the mmWave channel accurately.

3D non-stationary wideband circular tunnel channel models for high-speed train wireless communication systems

This paper proposes three-dimensional (3D) non-stationary wideband circular geometry-based stochastic models (GBSMs) for high-speed train (HST) tunnel scenarios. Considering single-bounced (SB) and multiple-bounced (MB) components from the tunnel's internal surfaces, a theoretical channel model is first established. Then, the corresponding simulation model is developed using the method of equal volume (MEV) to calculate discrete angular parameters. Based on the proposed 3D GBSMs, important time-variant statistical properties are investigated, such as the temporal autocorrelation function (ACF), spatial cross-correlation function (CCF), and space-Doppler (SD) power spectrum density (PSD). Results indicate that all statistical properties of the simulation model, verified by simulation results, can match well those of the theoretical model. The statistical properties of the proposed 3D GBSMs are further validated by relevant measurement data, demonstrating the flexibility and utility of our proposed tunnel GBSMs.