Sardar Muhammad Gulfam

A 3-D Propagation Model for Emerging Land Mobile Radio Cellular Environments.

A tunable stochastic geometry based Three-Dimensional (3-D) scattering model for emerging land mobile radio cellular systems is proposed. Uniformly distributed scattering objects are assumed around the Mobile Station (MS) bounded within an ellipsoidal shaped Scattering Region (SR) hollowed with an elliptically-cylindric scattering free region in immediate vicinity of MS. To ensure the degree of expected accuracy, the proposed model is designed to be tunable (as required) with nine degrees of freedom, unlike its counterparts in the existing literature. The outer and inner boundaries of SR are designed as independently scalable along all the axes and rotatable in horizontal plane around their origin centered at MS. The elevated Base Station (BS) is considered outside the SR at a certain adjustable distance and height w.r.t. position of MS. Closed-form analytical expressions for joint and marginal Probability Density Functions (PDFs) of Angle-of-Arrival (AoA) and Time-of-Arrival (ToA) are derived for both up- and down-links. The obtained analytical results for angular and temporal statistics of the channel are presented along with a thorough analysis. The impact of various physical model parameters on angular and temporal characteristics of the channel is presented, which reveals the comprehensive insight on the proposed results. To evaluate the robustness of the proposed analytical model, a comparison with experimental datasets and simulation results is also presented. The obtained analytical results for PDF of AoA observed at BS are seen to fit a vast range of empirical datasets in the literature taken for various outdoor propagation environments. In order to establish the validity of the obtained analytical results for spatial and temporal characteristics of the channel, a comparison of the proposed analytical results with the simulation results is shown, which illustrates a good fit for 107 scattering points. Moreover, the proposed model is shown to degenerate to various notable geometric models in the literature by an appropriate choice of a few parameters.

On the spatial characterization of 3-D air-to-ground radio communication channels

A three dimensional (3-D) geometric channel model is proposed for air-to-ground (A2G) communication environments. The proposed model considers air station (AS) and ground base station (BS) located at foci points of a virtual bounding ellipsoid corresponded from the delay of longest propagation path. The scattering region around the ground BS is thus designed based on this virtual bounding ellipsoid truncated by the ground plane and average rooftop level of the BSs surroundings. Closed-form expressions for joint and marginal probability density functions (PDFs) of angle of arrival (AoA) observed at both AS and BS in correspondence with both azimuth and elevation planes are derived. Impact of various physical channel parameters on the elevational and azimuthal angular dispersion is thoroughly observed; which is useful in designing advanced signal processing techniques for directional antennas employed in aeronautical communication links. To establish the models validity, the obtained analytical results are compared with simulation results. For 105 uniformly distributed scattering points, the best matching is observed between simulation and analytical results.

A tunable 3-D statistical channel model for spatio-temporal characteristics of wireless communication networks: A tunable 3-D statistical channel model

A new three-dimensional (3-D) geometric channel model is proposed with multiple degrees of freedom in its scattering volume geometry, which enables accurate modeling of realistic propagation scenarios for emerging Machine-to-Machine (M2M) wireless networks. Analytical expressions for the joint and marginal statistics in delay and angular domains are derived and we present the impact of various physical channel parameters such as link distance, antenna heights, size and position of scattering region, as well as shape and orientation of scattering region on delay and angular spread of the proposed model. The derived analytical results are validated with simulations and are also shown to provide a good fit to published empirical data-sets. Relative to existing models, the proposed model is shown to more accurately adapt to different propagation environments envisioned for emerging communication scenarios such as in indoor pico-cellular and Vehicle-to-Vehicle (V2V) communication applications. Copyright c

Small-Scale Fading Statistics of Emerging 3-D Mobile Radio Cellular Propagation Channels

In delivering fifth generation (5G) communication networks, the fundamental advancements in the scale of antenna arrays, density of networks, mobility of communicating nodes, size of cells, and range of frequencies necessitate the derivation of an appropriate and reliable channel model. A tunable three dimensional (3-D) geometric channel model comprehending the mobility of user terminal together with high degree of flexibility in modelling the shape, orientation, and scale of the scattering region is proposed. Characterization of Doppler spectrum, quantization of multipath dispersion in angular domain, and second order fading statistics of the radio propagation channel is presented. Mathematical expressions for joint and marginal probability density function of Doppler shift and multipath power are derived for this advanced 3-D hollow geometric scattering model. Next, an analysis on the Doppler spectrum is presented, where the impact of various physical channel parameters on its statistical characteristics is analyzed. Since, the quantification of multipath dispersion in 3-D angular domain is of vital importance for designing large scale planner antenna arrays with very high directional resolution for emerging 5G communications, therefore, a thorough analysis on the multipath shape factors (SFs) of the proposed analytical 3-D channel model is conducted. Finally, the analysis on SFs is extended for characterization of second order fading statistics of multipath channels.

Analysis on multipath shape factors of air-to-ground radio communication channels

This paper first presents an extension of a notable three dimensional (3D) channel model for air-to-ground (A2G) radio propagation environments, from the plain distribution of angular energy to the quantization of multipath shape factors (SFs). Next, the paper presents a comprehensive analysis on the characteristics of multipath SFs for A2G radio propagation environments observed at both ends of the link. The analysis include the impact of various physical channel parameters on angular spread, true standard deviation, angular constriction, and direction of maximum fading. These SFs are obtained by exploiting the analytical and empirical results available in the literature for the distribution of energy in 3D angular space. Finally, a mechanism for classification of A2G propagation environments into taxiing, en-route, and take-off scenarios on the basis of SFs is presented.

Angle and time of arrival characteristics of 3D air-to-ground radio propagation environments

A three dimensional (3D) geometric channel model is proposed for ground-to-air (G2A) and air-to-ground (A2G) communication links. A low-elevated ground station (GS) and a high-elevated air station (AS) are taken at foci points of a virtual bounding ellipsoid corresponded from known knowledge of delay of longest propagation path. The effective region of scatterers around the GS is designed on the basis of this ellipsoid truncated by the average rooftop level (or average height of sea waves) and ground plane. Closed-form expressions for joint and marginal probability density functions (PDFs) of angle of arrival (AoA) observed at AS and GS in correspondence with azimuth and elevation angles are derived. Furthermore, closed-form expressions for density of energy with respect to the delay of arriving multipath waves corresponded from both the elevation and azimuth AoA are derived independently when observed from either end of the communication link. Moreover, effect of different physical parameters of the channel on distribution of energy in angular and temporal domains is presented. The comparison of analytical results with results of a notable model is also presented. In order to verify the derived analytical expressions, a comparison of analytical results with the performed simulation results is presented, which shows a good match.