space-Doppler Power Spectral Density Research Articles

A three‐dimensional wideband mmWave multiple‐input multiple‐output channel model for aerial reconfigurable intelligent surface‐assisted communication systems

SummaryThis paper presents a wideband millimeter wave (mmWave) channel model for aerial reconfigurable intelligent surface (ARIS) communications, in which the reconfigurable intelligent surface (RIS) is attached to an unmanned aerial vehicle (UAV) to enable intelligent signal reflections in the air. The model is established according to standard 3GPP channel models and considers important propagation factors, for example, large‐scale fading, small‐scale fading, and radiation pattern of reflection units (RUs). In addition, the model assumes three‐dimensional (3D) rotations of RIS and can capture its effects on channel characteristics. Based on the model, we propose a design method for RIS reflection phases. Statistics including channel amplitude, spatial, temporal, and frequency correlation functions (CFs), and space‐Doppler power spectral density (SD‐PSD) are obtained. The impacts of RU number, UAV height and speed, and RIS rotation on channel statistics are investigated. Results suggest that the designed reflection phases can effectively mitigate multipath fading and Doppler effect. Compared to the yaw angle of the UAV platform, channel characteristics are more sensitive to the roll and pitch angles.

3D non-stationary vehicle-to-vehicle MIMO channel model for 5G millimeter-wave communications

Vehicle-to vehicle (V2V) is one of the most challenging scenarios in the fifth-generation (5G) millimeter-wave (mmW) mobile communication networks. Existing models cannot be utilized without development for compatibility with modern measurements, which have proved that the wide-sense stationary (WSS) modeling assumption is valid only for very short intervals. In this paper, a novel three-dimensional (3D) geometry-based stochastic model (GBSM) for non-stationary (non-WSS) narrowband V2V multi-input-multi-output (MIMO) channel with both 3D fixed and moving scatterers around the transmitter (Tx) and the receiver (Rx) is proposed. The azimuth angle of departure (AAoD), elevation angle of departure (EAoD), azimuth angle of arrival (AAoA) and elevation angle of arrival (EAoA) of the 3D moving scatterers have been considered as time varying angles, and this makes the model non-stationary. Based on the proposed model, the statistical properties, including space-time correlation function (STCF), space-Doppler power spectral density (SD-PSD), level crossing rate (LCR), and average fade duration (AFD) are derived and compared with those of measured data and state-of-the-art channel models. Finally, the close agreement between results reveal that the proposed 3D model with 3D moving scatterers reflects the real-world V2V channel characteristics, especially in 5G mmW networks.

A 3-D Geometry-Based Stochastic Model for UAV-MIMO Wideband Nonstationary Channels

In this paper, we propose a 3-D geometry-based stochastic model for multi-input multioutput wideband nonstationary channels between the unmanned aerial vehicle (UAV) and the ground user. The proposed model uses a single concentric-cylinders model, where the signal is a superposition of a line-of-sight component and single-bounced rays. In order to describe the nonstationarity of the channel, time-varying angels have been properly derived and added in the proposed model. At the same time, based on the reference model, we derive the expressions of the channel statistical properties of the space–time–frequency correlation function and space-Doppler power spectral density. In addition, corresponding deterministic and stochastic simulation models are developed based on the reference model. Moreover, we investigate the influence of some important UAV-related parameters on channel statistical properties as well as the channel nonstationarity. Some interesting observations and conclusions are obtained, which are helpful for the design of UAV communication systems. Finally, the great agreement between simulation models and the reference model demonstrates not only the utility of simulation models but also the correctness of the theoretical derivations and simulations.

Impact of Moving Scatterers on Vehicle-to-Vehicle Narrow-Band Channel Characteristics

A 3-D geometrical propagation model that includes both stationary and moving scatterers around the transmitter and the receiver for narrow-band multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V-to-V) communications is proposed. Based on the geometrical model, a 3-D parametric reference model for narrow-band MIMO V-to-V multipath fading channels is developed. From the reference model, the corresponding space-time correlation function (ST-CF) and space-Doppler power spectral density (SD-PSD) are derived for a 3-D nonisotropic scattering environment. Finally, the theoretical results are compared with measured data in an urban surface street and Interstate highway road surfaces. The close agreement between the analytically and empirically obtained channel statistics confirms the utility of the proposed model and shows the importance of including moving scatterers in propagation models.

A Semiempirical MIMO Channel Model in Obstructed Viaduct Scenarios on High-Speed Railway

A semiempirical multiple-input multiple-output (MIMO) channel model is proposed for high-speed railway (HSR) viaduct scenarios. The proposed MIMO model is based on the combination of realistic single-input single-output (SISO) channel measurement results and a theoretical geometry-based stochastic model (GBSM). Temporal fading characteristics involvingK-factor and Doppler power spectral density (PSD) are derived from the wideband measurement under an obstructed viaduct on Zhengzhou-Xi’an HSR in China. The GBSM composed of a one-ring model and an elliptical model is employed to describe the entire propagation environment. Environment-related parameters in the GBSM are determined by the measured temporal fading properties. And a close agreement is achieved between the model results and measured data. Finally, a deterministic simulation model is established to perform the analysis of the space-time correlation function, the space-Doppler PSD, and the channel capacity for the measured scenario. This model is more realistic and particularly beneficial for the performance evaluation of MIMO systems in HSR environments.

Three-dimensional modeling and simulation of wideband MIMO mobile-to-mobile channels

A three-dimensional (3-D) geometrical propagation model for wideband multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) communications is proposed. Based on the geometrical model, a 3-D parametric reference model for wideband MIMO M-to-M multipath fading channels is developed. From the reference model, the corresponding space-time-frequency correlation function is derived for a 3-D non-isotropic scattering environment. It is shown that the time and frequency dispersion of a wide sense stationary uncorrelated scattering channel cannot be treated independently, contrary to common practice. From the space-time-frequency correlation function, the space-Doppler power spectral density and the power space-delay spectrum are derived and compared with measured data. Finally, a new sum-of-sinusoids based simulation model for wideband MIMO M-to-M Ricean fading channels is proposed. The statistics of the simulation model are verified by simulation. The results show that the simulation model is a good approximation of the reference model.