In optical communications, four-dimensional (4D) modulation formats encode information onto the quadrature components of two arbitrary orthogonal states of polarisation of the optical field. Many ...analytical models available in the optical communication literature allow, within a first-order perturbation framework, the computation of the average power of the nonlinear interference (NLI) accumulated in coherent fibre-optic transmission systems. However, all such models only operate under the assumption of transmitted polarisation-multiplexed two-dimensional (PM-2D) modulation formats, which only represent a limited subset of the possible dual-polarisation 4D (DP-4D) formats. Namely, only those where data transmitted on each polarisation channel are mutually independent and identically distributed. This paper presents a step-by-step mathematical derivation of the extension of existing NLI models to the class of arbitrary DP-4D modulation formats. In particular, the methodology adopted follows the one of the popular enhanced Gaussian noise model, albeit dropping most assumptions on the geometry and statistic of the transmitted 4D modulation format. The resulting expressions show that, whilst in the PM-2D case the NLI power depends only on different statistical high-order moments of each polarisation component, for a general DP-4D constellation, several other cross-polarisation correlations also need to be taken into account.
This paper looks into the realization of digital twin (DT) technology in unmanned aerial vehicle (UAV) networks. We propose, in particular, a framework for DT-based UAV applications in which distinct ...jobs in the digital twin interact with UAVs in the physical world via task manager scheduling. Furthermore, we investigate the use of 3D mmWave Radar imaging on UAVs and apply it to the process of radio frequency (RF) characterizing. After that, the method of 3D ray-tracing is employed to accomplish channel modelling of UAVs, which reflects RF domain digital twin match. Finally, we present numerical results to demonstrate that our developed digital twin platform can provide accurate RF presentation of UAV and therefore accomplish smart operating and administration of the actual UAV network.
Conventional maritime communication struggles to provide high data rate services for Internet of Things (IoT) devices due to the variability of maritime environments, making it challenging to ensure ...consistent connectivity for onboard sensors and devices. To resolve this, we perform mathematical modeling of the maritime channel and compare it with real measurement data. Through the modeled channel, we verify the received beam gain at buoys on the ocean surface. Additionally, leveraging the modeled wave motions, we estimate future angles of the buoy to use the Extended Kalman Filter (EKF) for design beamforming strategies that adapt to the evolving maritime environment over time. We further validate the effectiveness of these strategies by assessing the results from an outage probability perspective. focuses on improving maritime communication by developing a dynamic model of the maritime channel and implementing a Kalman filter-based buoy motion tracking system. This system is designed to enable precise beamforming, a technique used to direct communication signals more accurately. By improving beamforming, the aim is to enhance the quality of communication links, even in challenging maritime conditions like rough seas and varying sea states. In our simulations that consider realistic wave motions, you've observed significant improvements in link quality due to the enhanced beamforming technique. These improvements are particularly notable in environments with high sea states, where communication challenges are typically more pronounced. The progress made in this area is not just a technical achievement; it has broad implications for the future of maritime communication technologies. This paper promises to revolutionize the way we approach communication in maritime environments, paving the way for more reliable and efficient information exchange on the seas.
To support the design of fifth-generation (5G) beamforming and beamtracking algorithms, a spatially consistent channel propagation model is needed, namely a model whose geometrical properties - ...angle-of-departure, angle-of-arrival, and delay of its multipath components - evolve smoothly while the receiver is in motion. The 3rd Generation Partnership Project (3GPP) has proposed two spatial consistency (SC) procedures - SC-A and SC-B - as part of its popular TR 38.901 model for 0.5 GHz to 100 GHz channels. In this paper, we perform a comparison of the two procedures with measurements to determine whether the procedures accurately fit our measurements. We use over 700 channel measurements collected with our high-resolution 28 GHz and 60 GHz directional channel sounders, across two indoor and three outdoor environments and for pedestrian and vehicular motion. We show that SC-A - a fully deterministic procedure - provides a much better approximation to the measured channel in all five environments than SC-B - a fully stochastic procedure. We also computed the correlation distance for both procedures - the distance over which they are valid - showing that SC-A's average correlation distance across all environments of 13.4 m is more than twice as long as SC-B's of 6.28 m, and that the channel is spatially consistent for significantly longer outdoors than indoors.
Long Range (LoRa) is a popular communication technology which has been used recently for many of the internet of things (IoT) applications. LoRa technology is being used for various smart city ...operations as well as in the field of smart agriculture. Some of the smart agricultural applications need LoRa propagation in vegetation medium. To model a wireless channel, several factors should be considered as those have significant impact on the performance of LoRa propagation through foliage medium. In this paper some of the possible factors are highlighted as those are responsible for the degradation of LoRa channel quality. Aslo an experimental study was undergone in the foliage medium (a line of five date palm trees) to investigate the LoRa physical layer performance utilizing different spread factors (SF7-SF12). The RSSI values were measured for the propagation through a line of trees and compared with the expected RSSI values. The result shows that the measured RSSI values are higher than the expected values for LoRa propagation in foliage medium. The result obtained in this paper may help LoRa propagation Channel modelling in foliage medium in future studies.
This paper presents an investigation of how to model the statistical properties of radio channels arising in industrial environments over long time horizons, e.g., hours and days. Based on extensive ...measurement campaigns, conducted at three different factory buildings, it is shown that for mobile transceivers the fading characteristics are Rayleigh or close to Rayleigh. However, for transceivers mounted at fixed locations, the use of conventional single fading distributions is not sufficient. It is shown that a suitable model structure for describing the fading properties of the radio channels, as measured by power, is a mixture of gamma and compound gamma-lognormal distributions. Furthermore, the complexity of the model generally increases with the observation interval. A model selection approach based on a connection between Kullback's mean discrimination information and the log-likelihood provides a robust choice of model structure. We show that while a (semi)-Markov chain constitute a suitable model for the channel dynamics the time dependence of the data can be neglected in the estimation of the parameters of the mixture distributions. Neglecting the time dependence in the data leads to a more efficient parametrization. Moreover, it is shown that the considered class of mixture distributions is identifiable for both continuous and quantized data under certain conditions and under those conditions a maximum likelihood under independence assumption estimator is shown to give consistent parameters also for data which are not independent. The parameter estimates are obtained by maximizing the log likelihood using a genetic and a local interior point algorithm.
6G IoV Networks Driven by RF Digital Twin Modeling Liu, Zengcan; Sun, Houjun; Marine, Gintare ...
IEEE transactions on intelligent transportation systems,
2024-March, 2024-3-00, Letnik:
25, Številka:
3
Journal Article
Recenzirano
Internet of Vehicles (IoV) is a crucial component of 6G mobile network, where energy efficiency is a major concern. To achieve green communication in IoV, this paper proposes a digital twin (DT) ...method and develops related machine learning-based energy-efficient approach. The channel model examined in this paper takes into account incident waves reflected by moving objects and the impacts of radio signals between various vehicles. 3D ray tracing is used to model the millimeter-wave channel in IoV to reflect radio frequency(RF)-domain digital twin matching. Finally, we present numerical results to justify the effectiveness of our proposed scheme.
Graph theory channel modeling is an efficient approach to simulate multipath radio propagation including the reverberation effect of electromagnetic waves. In this contribution, without modifying the ...modeling framework, we proposed a semi-deterministic channel modeling approach by associating the scatterers with realistic environment objects, and by calculating the coefficients of the propagation paths on the base of a physically sound and proven diffuse scattering theory. The diffuse multipath components are then combined with the specular components (SCs) simulated by ray-tracing (RT) to obtain a complete channel representation. The proposed method is evaluated in two reference scenarios at 3.8 and 60 GHz, respectively, by comparing the simulated channel characteristics with channel measurement data. Results show that the proposed method can accurately predict the channel characteristics in both the delay domain and the angular domain. The proposed approach is appropriate to model multipath propagation in confined indoor or dense-urban environment at millimeter (mm)-wave frequencies and above, where reverberation and rough-surface scattering can be important phenomena.
A Review on Terahertz Communications Research Kleine-Ostmann, Thomas; Nagatsuma, Tadao
Journal of infrared, millimeter and terahertz waves,
02/2011, Letnik:
32, Številka:
2
Journal Article
Recenzirano
The increasing demand of unoccupied and unregulated bandwidth for wireless communication systems will inevitably lead to the extension of operation frequencies toward the lower THz frequency range. ...Higher carrier frequencies will allow for fast transmission of huge amounts of data as needed for new emerging applications. Despite the tremendous hurdles that have to be overcome with regard to sources and detectors, circuit and antenna technology and system architecture to realize ultrafast data transmission in a scenario with extensive transmission loss, a new area of research is beginning to form. In this article we give an overview of emerging technologies and system research that might lead to ubiquitous THz communication systems in the future.
The objective of this paper is to derive a model for the irradiance distribution of underwater optical waves propagation in the combined presence of turbulence and air bubbles. The proposed ...distribution is based on modelling the medium index of refraction as a shot noise process and using the Rytov solution to the stochastic wave equation. Since the oceanic turbulence spectrum is different than the atmospheric spectrum, recent studies show that the well-known probability density functions poorly describe optical wave propagation underwater in the combined presence of air bubbles and turbulence, and that a mixture of distributions is generally needed. This conclusion, however, does not follow from theoretical investigations. Moreover, the physical aspects of the phenomena, such as the bubble size distribution, are not included in these models, and as such may limit their applicability. The approach introduced in this paper allows for including the environment physical properties directly in to the medium index of refraction.
In this paper, intensity distribution model is derived based on Rytov theory of propagation through weak turbulence. The physical processes in effect are directly included by assuming a shot noise index of refraction model.
Using the beam propagation method combined with the random phase screen method, the derived distribution is validated by simulation over a large range of turbulence levels and shows excellent agreement with the simulation data. In particular, the qualitative aspect of two peak distribution is modelled by the proposed distribution.
•A proposed approach for the intensity pdf of optical waves through random mediums.•The proposed approach incorporates the physical characteristics of the mediums.•Underwater optical waves in presence of turbulence and air bubbles is considered.•The model is verified through simulation of underwater turbulent environment .
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