Recently, IQRF has emerged as a promising technology for the Internet of Things (IoT), owing to its ability to support short- and medium-range low-power communications. However, real world deployment ...of IQRF-based wireless sensor networks (WSNs) requires accurate path loss modelling to estimate network coverage and other performances. In the existing literature, extensive research on propagation modelling for IQRF network deployment in urban environments has not been provided yet. Therefore, this study proposes an empirical path loss model for the deployment of IQRF networks in a peer-to-peer configured system where the IQRF sensor nodes operate in the 868 MHz band. For this purpose, extensive measurement campaigns are conducted outdoor in an urban environment for Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) links. Furthermore, in order to evaluate the prediction accuracy of well-known empirical path loss models for urban environments, the measurements are compared with the predicted path loss values. The results show that the COST-231 Walfisch–Ikegami model has higher prediction accuracy and can be used for IQRF network planning in LoS links, while the COST-231 Hata model has better accuracy in NLoS links. On the other hand, the effects of antennas on the performance of IQRF transceivers (TRs) for LoS and NLoS links are also scrutinized. The use of IQRF TRs with a Straight-Line Dipole Antenna (SLDA) antenna is found to offer more stable results when compared to IQRF (TRs) with Meander Line Antenna (MLA) antenna. Therefore, it is believed that the findings presented in this article could offer useful insights for researchers interested in the development of IoT-based smart city applications.
Abstract
The goal of the space-based quantum network is to form the backbone of the quantum internet for long-distance secure data transfer, networked distributed quantum information processing, and ...other applications. Consider that the quantum network evolved from a recent form where a satellite performs a sequence of satellite-to-ground quantum key distribution (SatQKD) missions that allow any two ground nodes to have the symmetric encryption keys, we here develop a framework for the SatQKD downlink modelling and scheduling analysis. Incorporated with the orbital calculation and the meteorological data to downlink SatQKD modelling, the dynamic characteristics of the satellite-to-ground optical transmission could be simulated. Our work shows that the satellite downlink scheduling allows for the possibility to consider different strategies for SatQKD missions such as extending connection for distant ground nodes, prioritized delivery and promoting keys utilization, which may guide design and analysis of future missions for future satellite application.
Communications inside an aircraft cockpit are currently based on wired connections especially for the audio headsets used by the pilots. A wireless headset would be an advantage in terms of comfort ...and flexibility but the use of classical radio frequencies is limited by interference and security issues. Optical wireless communication technology is an option for headset connectivity. Indeed, as optical beams are confined, this technology provides robustness against the risk of hacking, thus increasing security. In addition, the use of optical waves ensures the absence of radio-frequency disturbances. Using simulation, this article presents a thorough study of the optical wireless channel behavior inside the cockpit of an aircraft by considering a headset worn by a pilot possibly in motion and an access point at the ceiling. The impact of the characteristics of the environment model, such as the level of geometric description, the reflectivity of materials and for the first time, the ambient noise induced by the sun, is highlighted. System performance is evaluated in terms of optimal half-power angles and the necessary optical power of the light sources.
The new generation of communication technologies are constantly being pushed to meet a diverse range of user requirements such as high data rate, low power consumption, very low latency, very high ...reliability and broad availability. To address all these demands, fifth generation (5G) radio access technologies have been extended into a wide range of new services. However, there are still only a limited number of applications for radio frequency (RF) based wireless communications inside aircraft cabins that comply with the 5G vision. Potential interference and safety issues in on-board wireless communications pose significant deployment challenges. By transforming each reading light into an optical wireless access point (AP), light-fidelity (LiFi), could provide seamless on-board connectivity in dense cabin environments without RF interference. Furthermore, the utilization of available reading lights allows for a relatively simple, cost-effective deployment with the high energy and spectral efficiency. To successfully implement the aeronautical cabin LiFi applications, comprehensive optical channel characterization is required. In this paper, we propose a novel Monte Carlo ray-tracing (MCRT) channel modelling technique to capture the details of in-flight LiFi links. Accordingly, a realistic channel simulator, which takes the cabin models, interior elements and measurement based optical source, receiver, surface material characteristics into account is developed. The effect of the operation wavelength, cabin model accuracy and user terminal mobility on the optical channel conditions is also investigated. As a final step, the on-board direct-current biased optical orthogonal frequency division multiplexing (DCO-OFDM) performance is evaluated by using obtained in-flight LiFi channels. Numerical results show that the location of a mobile terminal and accurate aircraft cabin modelling yield as much as 12 and 2 dB performance difference, respectively.
Integrated Sensing and Communication (ISAC) has lately been highlighted as a critical enabler for B5G/6G wireless communication. Nevertheless, appropriate channel models that support communication ...and sensing are one of the main bottlenecks for efficient deployment of ISAC systems. This work addresses the problem of modelling multipath fading channels for ISAC systems for fixed wireless networks with mobile scatterers. We first highlight the limitations of existing models for multipath fading, namely, Jake's and Clarke's models. We then propose a Hybrid Clarke's model where we leverage the fact that all multipaths are not affected by the motion of the mobile scatterers. We then use the proposed channel model to evaluate a Doppler-based intruder detection system. Through various simulation results, we will showcase that the proposed channel model can effectively detect the intruder.
Vehicular communication channels are characterized by a non-stationary time- and frequency-selective fading process due to fast changes in the environment. We characterize the distribution of the ...envelope of the first delay bin in vehicle-to-vehicle channels by means of its Rician K-factor. We analyze the time-frequency variability of this channel parameter using vehicular channel measurements at 5.6 GHz with a bandwidth of 240 MHz for safety-relevant scenarios in intelligent transportation systems (ITS) . This data enables a frequency-variability analysis from an IEEE 802.11p system point of view, which uses 10 MHz channels. We show that the small-scale fading of the envelope of the first delay bin is Rician distributed with a varying K-factor. The later delay bins are Rayleigh distributed. We demonstrate that the K-factor cannot be assumed to be constant in time and frequency. The causes of these variations are the frequency-varying antenna radiation patterns, as well as the time-varying number of active scatterers, and the effects of vegetation. We also present a simple but accurate bimodal Gaussian mixture model, which allows to capture the K-factor variability in time for safety-relevant ITS scenarios.
The current growing interest in integrated sensing and communications (ISAC) for the next generation of radio access networks towards 6G is opening new challenges on the channel estimation and ...modelling. New frequency bands and novel techniques for joining the sensing and the transmission of information over the same waveform are becoming a hot topic for research. This paper proposes a generalist dual channel model description for ISAC and a technique to relate the sensing and the communications channel, which is described analytically and verified with measurements. The technique is based on exploiting the mutual interference between radar sensors to estimate the multipath communications channel between them.
Communication-based train control (CBTC) systems are a new generation of metro signaling system dependent on wireless technology with appropriate access point (AP) deployment. Improved AP deployment ...can improve the reliability of wireless CBTC systems. This paper proposes a method for optimizing the AP deployment in the data communication system of CBTC. To validate the optimal AP deployment, an integrated simulation environment is used to test the performance of the optimized AP deployments.
Ray-based Deterministic Channel Modelling for sub-THz Band Gougeon, Gregory; Corre, Yoann; Aslam, Mohammed Zahid
2019 IEEE 30th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC Workshops),
2019-Sept.
Conference Proceeding
Odprti dostop
Future wireless communications systems will require large network capacities beyond the capabilities of present and upcoming 5G technology. The trend of considering higher frequencies for their large ...bandwidths continues today into the sub-THz domain. The BRAVE project considers the frequencies in the 90-200 GHz spectrum, which have been considered in this paper. The challenges of channel modelling at sub-THz frequencies are described along with extensions made to a ray-based deterministic tool. The geographical and physical accuracies inherent to the ray-based tool are exploited to simulate two different scenarios. The first scenario is an indoor office scenario and the second is an outdoor in-street scenario. The application of the updated channel modelling properties of the ray-based tool provides interesting perspectives into the sub-THz channel modelling. This permits the development of realistic models for the evaluation, characterization and eventual deployment of such systems.
In this paper, we investigate the impact of both static and dynamic effects of motion on Underwater visible light communication (UVLC) channels. While previous studies have focused on static channel ...modeling, we argue that dynamic channel modeling is crucial for accurate UVLC analysis. To model static and dynamic UVLC channels, we use the Monte Carlo ray tracing (MCRT) method in Zemax Optics Studio; a reliable and practical setup simulator that produces results similar to experimental data. We evaluate the effect of channel coding on system performance by comparing nine different combinations and using Goodness-of-Fit (GoF) tests to determine the best-fit distribution. Our results reveal that the static case outperforms the dynamic case in terms of raw performance without any coding. However, we also show that the bit error rate (BER) is severely impacted in various realistic scenarios for a dynamic environment. To improve the BER and achieve adequate received signal quality, we recommend using convolutional codes. This paper emphasizes the importance of dynamic channel modeling in UVLC and provides practical solutions to enhance the UVLC performance in dynamic environments. The findings of our study provide valuable insights into the performance of UVLC systems and emphasize the need for researchers and designers to account for the dynamic realistic behavior in the underwater channel to achieve optimal performance in UVLC systems for underwater communication applications.
PDF
