Channel Measurement and Modeling

Radio channel models for 60 GHz very-high-speed radio systems in hospital environments are presented. Two possible applications of those systems have been considered: real-time video streaming for angiography and ultrasonic imaging. Channel modeling was performed for delay domain multipath characteristics based on extensive radio channel measurement campaigns in angiography and ultrasonic inspection rooms. The measurement results revealed that the shapes of the power delay profiles in the angiography and ultrasonic imaging rooms were significantly different from that reported in the IEEE802.15 TG3c and IEEE802.11 TGad channel models. For this reason, novel model structures were developed to model radio channels in these hospital scenarios accurately. Statistical descriptions of the channel model parameters are given based on the measurements, and, finally, implementation guidelines of the channel models are provided. The channel model validation results show a good agreement of root-mean-square delay spread between channel model outputs and channel measurements. The channel model is useful for the performance evaluation of the wireless systems in hospital environments.

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.

A number of radio channel models based on either geometrical or statistical methods have been proposed in literature. Many such models tend to simplify the scattering environment in indoor radio medium by assuming uniform distribution of scatterers and thereby overestimate the performance of the communication system. In this paper, we present a clustering based radio channel model for a wideband frequency selective Single Input Single Output (SISO) indoor wireless channel. With the transmitter and the receiver located at the foci of an ellipse, the scatterers are modeled to be present in form of clusters of scatterers distributed randomly inside the ellipse. Further, the size and hence number of scatterers inside the cluster may vary from cluster to cluster. Such representations of the scatterers are more realistic and therefore the proposed model is expected to provide better approximation to the actual indoor environment. The proposed model has been used to evaluate the performance of a generic SISO wireless link and the results are compared with those obtained using existing channel models. The proposed channel model can be extended to a frequency selective MIMO channel simulator enabling the performance evaluation of multi-antenna wideband communication systems.

Millimeter wave (mmWave) communication is a key technology for fifth generation (5G) wireless communication systems due to its tremendous bandwidth available to support high data rate transmission. This article investigates the recent developments and future challenges in 5G mmWave channel sounders, measurements, and models. Various channel sounders are comprehensively classified and compared. Channel measurements in diverse indoor and outdoor scenarios for different mmWave bands are surveyed. Meanwhile, a comparison of multiple mmWave bands, validation of mmWave massive multiple-input multiple-output (MIMO) channel properties, and measurement and modeling of human blockage effects are shown. Different channel modeling approaches including deterministic, semi-deterministic, and stochastic modeling methods are summarized. Some future research directions are also given.

The aim of the work presented in this paper wasto produce measurement-based wideband channel models forwireless local loops (WLL). The paper describes thefield measurements, the resulting channelcharacteristics, and the channel models based on the results.The impulse response measurements were performed at 1.28GHz in three different environments, namely urban,suburban high-rise, and suburban small house. At each site several rooms were selected, and ineach room a burst of impulse responses was recorded atseveral transmitter antenna positions. A long-termrecording was also performed in one location at each site. The multipath characteristics of theurban and suburban high-rise environments are verysimilar, with rms delay spreads of below 280 ns at 90%of positions. The suburban small-house environment can be expected to show less severe multipathpropagation. In general the multipath characteristicscan vary significantly even within a single room. Also,the long-term variation of the channel characteristics is significant. The results were combined intosix channel models, each with a different delay powerspectrum. The amplitude fading for all these ischaracterized by a Rician distribution with the Rician factor varying between 3 and 18 dB, thelevel-crossing rate between 0.1 and 0.51/s, and the fadedurations between 0.25 and 20 s.

In modern wireless communication systems, wireless channel modeling has always been a fundamental task in system design and performance optimization. Traditional channel modeling methods, such as ray-tracing and geometry- based stochastic channel models, require in-depth domain-specific knowledge and technical expertise in radio signal propagations across electromagnetic fields. To avoid these difficulties and complexities, a novel generative adversarial network (GAN) framework is proposed for the first time to address the problem of autonomous wireless channel modeling without complex theoretical analysis or data processing. Specifically, the GAN is trained by raw measurement data to reach the Nash equilibrium of a MinMax game between a channel data generator and a channel data discriminator. Once this process converges, the resulting channel data generator is extracted as the target channel model for a specific application scenario. To demonstrate, the distribution of a typical additive white Gaussian noise channel is successfully approximated by using the proposed GAN-based channel modeling framework, thus verifying its good performance and effectiveness.

Wireless channel modeling is critical to understanding and optimizing signal transmission. Wireless channels are influenced by many factors, including path loss, reflection, fading, and interference, making them complex and difficult to model and predict. Although some traditional wireless channel modeling methods are effective, they have limitations in handling complex multipath effects and nonlinear characteristics. Generative artificial intelligence (GAI) has the ability to generate robust data and therefore can be potentially used to model realistic wireless channel characteristics. However, there exist some challenges in GAI for wireless channel modeling, including physical layer network security issues, limited generalization ability, and the bandwidth consumption of centralized training. This article introduces a GAI-based wireless channel modeling framework, which leverages blockchain and federated learning to address efficiency, network security, and data privacy concerns in GAI channel modeling. Blockchain technology, through distributed ledgers and smart contracts, enables resource sharing and efficient utilization, enhancing computational efficiency and reducing network security risks. Federated learning allocates training tasks to different devices and nodes, thus allowing model training without centralizing data, protecting user privacy, and reducing network bandwidth usage. This article demonstrates the performance and effectiveness of the proposed framework through numerical results.

The 5th Generation (5G) of wireless mobile communication systems is currently the focus of many research projects and standardization bodies, such as the 3rd Generation Partnership Project (3GPP). Accurate modeling of the radio propagation channel is important for evaluating the performance of candidate technologies for 5G. However, the state-of-the-art radio channel models, such as the 3GPP 3D channel model, are not appropriate for analyzing all use-cases and scenarios commonly considered for 5G mainly due to its inherent stochastic nature. In particular, the difficulty in dealing with long-term spatial consistency and lack of correlation of small-scale parameters motivates using channel models based on ray-tracing. In fact, channel models that provide spatially consistent observations are of fundamental importance in assessing the performance of multiuser and massive MIMO schemes, by taking into account the spatial correlation of small-scale parameters, as well as of continuous ultra-dense networks (UDNs). This paper shows, by means of extensive numerical results, that the 3GPP 3D channel model consistently underestimates the achievable SIR in LoS multiuser MISO settings. However, in NLoS scenarios and urban micro-cell deployments, the 3GPP 3D channel model significantly overestimates the SIR experienced by the users. Hence, the achievable performance of massive MIMO schemes and continuous UDNs can only be assessed with channel models that take into account the spatial correlation of small-scale parameters.

In this article, an ultrawideband channel model within an intra‐vehicle environment is investigated.The electromagnetic wave propagation is simulated by full wave method in a three‐dimensional car structure. The channel measurement is conducted in frequency domain from 2 to 15 GHz in different scenarios. The calibration process is pointed out to ensure the accuracy in data analysis. The statistical analysis is presented using the channel impulse response calculated via inverse Fourier transform. The small scale features of the intra‐vehicle environment are then deduced. An interesting result shows that the delay spreads linearly decrease with the increased passenger number. The clustering channel model is developed based on Saleh–Valenzeula (S–V) model fitting into the vehicular environments with dense clusters and rays. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:322–326, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26568

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.

Due to the small radius and irregular shape of the limited area, the propagation environment is extremely complex, it is urgent to study the propagation characteristics of wireless channel during the limited complex area. In this paper, the propagation characteristic measurement was carried out during the limited area scene (office and staircase). The path loss and multipath effect of wireless channel were analyzed. Tapped Delay Line (TDL) model was proposed for studying the multi-path effect in the office and staircase scene. The results showed the amplitude of model taps was similar to the Nakagami distribution, and the m parameter of each tap was greater than 1. The m parameter and tap numbers of staircase was significantly larger than office, indicating that the waveguide effect of narrow structure of the stairs was more significant than open office environment. Finally, experiment test during limited complex area was carried out based on the multiple-input multiple-output model and the results were close to commonly theoretical channel models (Kronecker, Weichselberger). The wireless propagation characteristics and channel model studied in this paper provided effective theoretical basis and practical basis for link budget, coverage prediction and interference analysis of wireless communication during the limited complex area.

We propose an elevation-dependent Rice-Rayleigh/lognormal channel model for communications of personal and mobile users via non-geostationary satellites (NGSO S-PCNs). Based on this channel model, we discuss the performance of satellite diversity for NGSO S-PCNs. The parameters of the channel model are derived from channel measurements, which have been carried out for different elevation angles and in different environments. The measurements indicate that the channel behaviour in NGSO S-PCNs strongly depends on the elevation angle. In order to evaluate the performance of satellite diversity we present a method which allows the modelling of two statistically dependent satellite channels. The correlation between the channel states is also derived from channel measurements and depends on the azimuth separation of the two channels and on the elevation angles. We evaluate the performance of satellite diversity for LEO and MEO systems (Globalstar and ICO) and different mobile user environments. For these systems, some crucial benefits and drawbacks of satellite diversity are discussed. It can be shown that the service availability can be significantly improved by satellite diversity.

As the world warms up to the idea of millimeter wave (mmWave) communication and fifth generation (5G) mobile networks, realization slowly dawns that the data rate, latency, throughput, and other performance metrics that are used to assess a new wireless communication technology will not be enough to support the demands of envisioned futuristic applications. Thus there is an eagerness to further climb up the frequency ladder to use the large swathes of available spectrum in the 0.1 - 10 THz band which is expected to act as the key technology enabler to fulfill the requirements of the sixth generation (6G) wireless communication and possibly even beyond. Channel measurement and modeling are crucial to the design and deployment of future wireless communication systems and researchers across the world are putting their best foot forward to accelerate the process. The present article presents comprehensive assimilation of research efforts in the context of THz channel sounding. A detailed overview of the current channel sounding techniques is first introduced followed by their relevance to THz band channel measurement. An in-house novel channel sounder developed for THz band measurement is also briefly introduced in this context. The paper next provides elaborate dissemination of various measurement campaigns in the band of interest followed by the modeling techniques that are available in the literature and are being adopted for the THz band. Post the description of different challenges and future research directions in the context of sounding, measurement, and modeling the article is concluded.

Comparative link-level analysis and performance estimation of channel models for IIoT (Industrial-IoT) wireless communications

This paper deals with the modeling of the over sea radio channel and aims to establish sea turtles localization off the coast of Reunion Island, and also on Europa Island in the Mozambique Channel. In order to model this radio channel, a framework measurement protocol is proposed. The over sea measured channel is integrated to the localization algorithm to estimate the turtle trajectory based on Power of Arrival (PoA) technique compared to GPS localization. Moreover, cross correlation tool is used to characterize the over sea propagation channel. First measurement of the radio channel on the Reunion Island coast combine to the POA algorithm show an error of 18 m for 45% of the approximated points.