A Novel 6G ISAC Channel Model Combining Forward and Backward Scattering

A structural-multipath approach has been developed for constructing a spatiotemporal model of a single-mode decameter communication channel, which makes it possible to determine the two-frequency spatial correlation function of a single-mode decameter communication channel and to establish the dependences of frequency and spatial correlation intervals of fading on the operating frequency, diffuse ionosphere parameters, and radio link geometry. The method for constructing this model of a communication channel using the structural multipath approach includes four stages: 1) development of a multibeam spatiotemporal decameter model of a communication channel; 2) development of a radiophysical space-time model of radio wave propagation in a decameter radio link, taking into account the influence of inhomogeneities (diffusion) of the ionosphere based on the method of smooth perturbations; 3) identification of multipath and radiophysical models to determine the two-frequency spatial correlation function of the decameter of the communication channel; 4) determining the dependence of frequency and spatial correlation intervals of fading in a single-mode decameter communication channel on the choice of operating frequency, diffuse ionosphere parameters, and radio link geometry.

It is envisioned that the sixth generation (6G) and beyond 6G (B6G) wireless communication networks will enable global coverage in space, air, ground, and sea. In such networks, both base stations and users can be mobile and will tend to move continuously in three-dimensional (3D) space. Therefore, obtaining channel state information (CSI) in 3D continuous-space is crucial for the design and performance evaluation of future 6G and B6G wireless systems. On the other hand, new 6G technologies such as integrated sensing and communications (ISAC) will also require prior knowledge of CSI in 3D continuous-space. In this paper, a 3D continuous-space electromagnetic channel model is proposed for tri-polarized multi-user communications, taking into account scatterers and spherical wavefronts. Scattered fields are calculated using the method of moments (MoM) with high accuracy. Spherical wave functions are utilized to decompose the dyadic Green’s functions that connect the transmitted source currents and the received electric fields. Simulation results demonstrate that transmit power, apertures, scatterers, and sample intervals have significant impacts on statistical properties and channel capacities, providing insights into the performance of continuous-space electromagnetic channel models and the design of future wireless systems.

Разработана компьютерная модель спутникового канала связи с учетом влияния доплеровского сдвига по частоте и стороннего спутника связи. Компьютерная модель построена в графической среде имитационного моделирования Simulink, которая входит в программный пакет MATLAB. В статье рассматривается имитационная модель спутникового канала связи с использованием сигнала MSK (Minimum Shift Keying). В ходе работы изучены и применены алгоритмы цифровой обработки сигналов при разработке компьютерной модели спутникового канала связи. По заданным параметрам принимаемого сигнала определены основные параметры цифрового демодулятора сигнала MSK, такие как частота повторения бита, частота дискретизации, минимальная разрядность аналого-цифрового преобразователя (АЦП), количество уровней квантования, частота среза цифрового фильтра-дифференциатора. В результате компьютерного моделирования спутникового канала связи было исследовано влияние отстройки по частоте сигнала MSK и уровня мешающего сигнала (стороннего спутника) на помехоустойчивость модема. По результатам моделирования получены графики зависимости вероятности ошибки приема бита от уровня мешающего сигнала и вероятности ошибки от отстройки по частоте. Разработанная компьютерная модель существенно расширяет круг задач, связанных с оперативной оценкой параметров электромагнитной совместимости (ЭМС) и радиоподавления в группировках подвижных РЭС.

As vehicular communications for beyond fifth‐generation (B5G) and sixth‐generation (6G) is picking up interests from academia and industry recently, more and more research and development have been devoted towards the establishment of vehicular communications for B5G and 6G that is capable of supporting the ever more intelligent transportation systems. One key facilitating the design and improvement of vehicular communications for B5G and 6G is channel modelling, which is widely regarded as the foundation of all communication and networking systems. In this paper, the authors focus on the research and analysis of B5G and 6G vehicular channel measurements and modelling. By emphasising the new requirements and challenges that the emerging B5G and 6G technologies and frequency bands bring to vehicular communication channel measurements and modelling, they present an overview of the existing work and identify the limitations therein, and provide guidelines on the channel model development and adoption for various system development and verification objectives. Finally, future challenges related to vehicular channel measurements, modelling, and their application for B5G and 6G are addressed.

The model of the communication channel with phase noises is proposed. The prototype of synchronization system, which works at the phase noises in the communication channel, is made. The research of the pseudorandom signal spectrum is carried out depending on the shift register size in the m-sequence generator. The research results of the phase noise influence on the transmitted FM signal are presented.

Unleashing the potential of sixth generation (6G) wireless networks in smart energy grid management: A comprehensive review

A simple analytical model of the wireless infrared communication channel in indoor environments is presented. The infrared signal is modeled as the combination of a diffuse component and a line-of-sight (LOS) or direct component. For the diffuse component alone, the properties of the channel are found using Ulbricht's integrating sphere. When a LOS component is also present, the transfer function depends upon the Rician factor K given by the ratio of the electrical power in the LOS and diffuse signals after the detector. For small K, the transfer function shows notches down to low frequencies, but due to the nature of light never for zero frequency. We confirm that a K-factor >or=13 dB is required also in infrared wireless links in order to support distortionless data transmission beyond 100 Mbit/s. Increasing the directivity at the receiver and/or at the transmitter improves the effective value of K. Here, we show that a moderate directivity will be sufficient for high-speed infrared communication in typical indoor scenarios.

This paper presents an efficient technique of continuous communication channel's experimental research for identification of amplitude-frequency characteristics (AFC). The technique is based on Volterra model and founded on the application of the approximating method of identification of nonlinear dynamic system. The identification is carried out by means of compiling the linear combinations of responses from researched system to the test polyharmonic signals with different amplitudes. Designed firmware, realizing the methodology of identification, is used for construction of informational model of communication channel in the form of first and second orders AFC's on the basis of input-output experiment's data, using harmonic and biharmonic test signals.

This paper presents a comprehensive literature review on applications of economic and pricing theory for resource management in the evolving fifth generation (5G) wireless networks. The 5G wireless networks are envisioned to overcome existing limitations of cellular networks in terms of data rate, capacity, latency, energy efficiency, spectrum efficiency, coverage, reliability, and cost per information transfer. To achieve the goals, the 5G systems will adopt emerging technologies such as massive multiple-input multiple-output, mmWave communications, and dense heterogeneous networks. However, 5G involves multiple entities and stakeholders that may have different objectives, e.g., high data rate, low latency, utility maximization, and revenue/profit maximization. This poses a number of challenges to resource management designs of 5G. While the traditional solutions may neither efficient nor applicable, economic and pricing models have been recently developed and adopted as useful tools to achieve the objectives. In this paper, we review economic and pricing approaches proposed to address resource management issues in the 5G wireless networks including user association, spectrum allocation, and interference and power management. Furthermore, we present applications of economic and pricing models for wireless caching and mobile data offloading. Finally, we highlight important challenges, open issues and future research directions of applying economic and pricing models to the 5G wireless networks.

Caching content of small base stations (SBSs) is a promising approach in the fifth generation (5G) wireless networks for decreasing the transmission delay and energy consumption. The key issue in caching is effective cooperation among SBSs for full usage of the caching to reduce the systems cost. In this paper, we first introduce the architecture of wireless cellular networks with caching in 5G. We divide the caching space into two parts: One caches the fixed content purchased by telecom operators from the remote service providers, and the other one caches contents for wireless transmission. Then, we propose the cooperative caching scheme based on content-exchanged, where each user can get its demanded data from either local SBS or purchasing the contents stored in the neighboring cooperative SBSs. We further prove the concavity of system costs regarding to the proportion between the two parts. We also propose a mechanism to search for the minimal system costs. Finally, by simulations, we prove that the performance of our proposed cooperative caching scheme is better than that of the traditional cache schemes without purchasing the contents between SBSs.

As the demand for higher speed data transmissions continues to increase exponentially beyond the speed-limit of the fourth generation (4G) wireless networks due to the rapid spectrum depletion of the microwave frequency bands below 6 GHz, it has become quite evident that the existing wireless communication systems will eventually be constrained from meeting the huge throughput requirements for various emerging applications beyond 4G wireless networks. In order to sustain the future market dominance of wireless communications, the narrowness of wireless bandwidths in the existing systems, which has become a key issue for the upcoming wireless systems, needs to be addressed by looking beyond the traditional microwave spectrum domain through the exploitation of the huge bandwidths available in the millimeter wave bands. In this work, we have conducted the review for a series of measurements at various microwave bands, below 6 GHz and above, to study the behavior of ultra-wideband (UWB) channels, typically in different indoor and outdoor environments. These measurements have been used to gain a useful insight into the path loss and time dispersion parametric behaviors of the 5G channel and to investigate the channel characterization of the UWB signals within spatially restricted locations. Moreover, these measurements have been used to evaluate the newest channel model and channel prediction which have proposed for 5G.

EGHR: Efficient group-based handover authentication protocols for mMTC in 5G wireless networks

Unmanned aerial vehicles (UAVs) have stroke great interested both by the academic community and the industrial community due to their diverse military applications and civilian applications. Furthermore, UAVs are also envisioned to be part of future airspace traffic. The application functions delivery relies on information exchange among UAVs as well as between UAVs and ground stations (GSs), which further closely depends on aeronautical channels. However, there is a paucity of comprehensive surveys on aeronautical channel modeling in line with the specific aeronautical characteristics and scenarios. To fill this gap, this paper focuses on reviewing the air-to-ground (A2G), ground-to-ground (G2G), and air-to-air (A2A) channel measurements and modeling for UAV communications and aeronautical communications under various scenarios. We also provide the design guideline for managing the link budget of UAV communications taking account of link losses and channel fading effects. Moreover, we also analyze the receive/transmit diversity gain and spatial multiplexing gain achieved by multiple-antenna-aided UAV communications. Finally, we discuss the remaining challenge and open issues for the future development of UAV communication channel modeling.

This work proposes a new model of reconfigurable intelligent surface (RIS) called cognizable RIS (CRIS) that is specifically designed to meet the unique demands of users who require extreme-ultra-reliable and low-latency Communication (xURLLC) in the sixth generation (6G) wireless networks. The programmable elements in the proposed CRIS unit can adapt to different modes of operation to provide significant performance gain. To improve reliability at the receiver, we integrate unmanned aerial vehicles with the CRIS module, which enhances network performance through beamforming and mobility. Our study focuses on maximizing the sum throughput in a multiple-input multiple-output scenario using the rate-splitting multiple access communication system. To achieve this, we introduce a novel hybridized multi-agent-based deep reinforcement learning (DRL) algorithm for optimal resource allocation that maximizes the sum throughput. We incorporate long-short-term memory (LSTM) networks into our proposed DRL to address the temporal dependencies due to stochastic channel conditions. By utilizing the proposed LSTM-based multi-agent DRL (MA-DRL) algorithm, we achieve notable gains of 11.7% and 26.9% in sum throughput over widely recognized DRL benchmark algorithms, all while adhering to xURLLC’s stringent maximum packet error probability constraint of 10−9.

The intelligent transportation system (ITS) was supported by the sixth generation (6G) wireless networks, since it has great potential to realize intelligent transportation with the benefit for the society and economy. In order to overcome the practical problem of spectrum scarcity, ultra-low latency, large-scale connectivity in ITS, we propose a cooperative multiple-input single output non-orthogonal multiple access (MISO-NOMA) for ITS with intelligent reflecting surface (IRS) and simultaneous wireless information and power transfer (SWIPT). An user fairness optimization problem is formulated to maximize the fairness rate of the vehicles, subject to the quality of service requirements of the vehicles and the successive interference cancellation. The optimization problem involves the transmit beamformers design, the IRS reflection matrix design, and the power splitting ratio of the SWIPT, which lead to the problem is difficult to solve. For solving the challenging problem, an iterative successive convex approximation and semi-definite relaxation based algorithm is proposed. Explicitly, we firstly adopt the method of reconstructing epigraph for simplification due to the objective function is non-convex, and then the original problem is decomposed into two sub-problems that are easy to solve. Finally, Experimental results illustrate that the user fairness of the proposed cooperative MISO-NOMA for ITS with IRS and SWIPT is better than that of both the IRS-NOMA for ITS without SWIPT and the IRS-OMA for ITS.