Large-scale radio propagation path loss measurements and predictions in the VHF and UHF bands

For decades now, a lot of radio wave path loss propagation models have been developed for predictions across different environmental terrains. Amongst these models, empirical models are practically the most popular due to their ease of application. However, their prediction accuracies are not as high as required. Therefore, extensive path loss measurement data are needed to develop novel measurement-oriented path loss models with suitable correction factors for varied frequency, capturing both local terrain and clutter information, this have been found to be relatively expensive. In this paper, a large-scale radio propagation path loss measurement campaign was conducted across the VHF and UHF frequencies. A multi-transmitter propagation set-up was employed to measure the strengths of radio signals from seven broadcasting transmitters (operating at 89.30, 103.5, 203.25, 479.25, 615.25, 559.25 and 695.25 MHz respectively) at various locations covering a distance of 145.5 km within Nigerian urban environments. The measurement procedure deployed ensured that the data obtained strictly reflect the shadowing effects on radio signal propagation by filtering out the small-scale fading components. The paper also, examines the feasibilities of applying Kriging method to predict distanced-based path losses in the VHF and UHF bands. This method was introduced to minimize the cost of measurements, analysis and predictions of path losses in built-up propagation environment

5G-enabled Mobile Operating Hospital and Emergency Care Service

Critical care has frequently been fatal for trauma patients suffering from hemorrhage. The pre-hospital communication gap between the paramedics and the doctors contributes most towards this. This paper discusses a system model of a 5G-enabled communication architecture among the major trauma centres in the Greater Manchester. An Internet of sensors acquires and wirelessly communicates biosignals from the patient in real time, using 5G. These signals are then displayed as parameters to the closest trauma care management centres. This paper proposes a connectivity model that supports such a system by assessing and identifying the most optimal path for signal transmittance. A system-level 5G network modelling and simulation findings reveal that a signal-to-noise ratio of over 2dB is achieved for two base stations between the incident site and the nearest emergency medical centre. This value decreases by over 5 dB as the number of base station doubles. Hence, reconfigurable 5G base stations connectivity subsystems are required for critical vertical use cases of the radio standard

Sub- 6 GHz 5G Spectrum for Satellite-Cellular Convergence Broadband Internet Access in Nigeria

Broadband access drives the global digital economy and has triggered the emergence of newer radio access technologies to meet data-driven consumers' expectations. In the period 2019-2025, it is estimated that the compound annual growth rate (CARG) of Sub-Sahara Africa will be above 28 % though ranked lowest amongst other regions. The Covid-19 pandemic has occasioned an unprecedented global demand for broadband internet access. Nigeria's broadband access is 42.02 %, which needs an advanced radio communication network infrastructure upgrade in order to bridge the current gap. Consequently, satellite-cellular convergence is a game-changer for increased rural and urban broadband connectivity penetration. The emergence of the fifth-generation (5G) network is expected to break new market share grounds and increase internet penetration. This paper focuses on the frequency range 1 (FR1: 450 – 7125 MHz) band due to their advantages, including broader coverage, better capacity, and low-cost deployment in sub-Saharan Africa. This paper presents the current usage of Nigeria spectrum bands allocated for mobile communication in the sub-7 GHz band. Potential spectrum bands such as 450-470 MHz, 1427-1518 MHz, 2300-2400 MHz, 3600-4200 MHz, 4400-5000 MHz, 5480-5710 MHz 5900-7125 MHz are suggested to add to the already recommended bands due to their low utilization (i.e., below 10 % average duty cycle). In addition, it is suggested to deploy carrier aggregation methodology to meet gigabit speed for 5G in Nigeria

Design of a 3.8-GHz Microstrip Patch Antenna for Sub-6 GHz 5G Applications

This paper presents a design of a centre-fed Rectangular Microstrip Patch Antenna (RMSA) that resonates at exactly 3.8 GHz. The effect of the dielectric material’s choice, substrate height, dielectric constant, and the substrate material is on the RMSA for a constant resonant frequency while maintaining signal integrity and reducing signal loss. The antenna’s gain and input return loss are improved by adjusting the upper and lower bounds of the height of the dielectric substrate. Results show that a maximum bandwidth of 350 MHz, a gain of 7.77 dBi, and input return loss (S11) of below–33 dB were obtained. Furthermore, a smaller dielectric constant below 2.5 and a Voltage Standing Wave Ratio (VSWR) below 2 dB will conveniently provide a wider bandwidth (BW) of over 250 MHz which is convenient to meet frequency range 1 (FR1) bandwidth expectation

A review of dust-induced electromagnetic waves scattering theories and models for 5G and beyond wireless communication systems

Dust particles and sand storms can cause attenuation and cross-polarization of electromagnetic wave propagation, especially at high frequencies above 10 GHz. Dust attenuation has been the focus of many research works, mainly with the deployment of a 5G wireless network in the FR-2 band (mmWave band, 23–53 GHz with TDD). This has led to the development of novel models to accurately predict and estimate attenuation. However, the existing review works have not adequately provided extensive taxonomies for these models to show the state-of-art and future research directions. This paper aims to bridge this gap by providing a comprehensive review of all electromagnetic scattering models in terms of their strengths, weaknesses, and applications. Lessons learned from the detailed survey have been stated and discussed extensively. Key findings from this review indicate that all the models developed were limited to the region where they were developed, with frequency and visibility levels as the two main parameters. The survey across regions showed no model was developed for Region 2, including the Americas, Greenland, and some of the eastern Pacific Islands. Among the dry regions of the globe, where dust and sand storms can occur either occasionally or frequently, it can be seen that only a few parts of these desert regions of Africa (Region 1) and Asia (Region 3) have been considered by authors for the development of prediction models for attenuation due to dust storms. Thus, this also shows the limitations of the overall deterministic models and presents the crucial need to develop new models or modify existing models to accurately predict dust attenuation in other regions, particularly in Africa

A Review on Rain Signal Attenuation Modeling, Analysis and Validation Techniques: Advances, Challenges and Future Direction

Radio waves are attenuated by atmospheric phenomena such as snow, rain, dust, clouds, and ice, which absorb radio signals. Signal attenuation becomes more severe at extremely high frequencies, usually above 10 GHz. In typical equatorial and tropical locations, rain attenuation is more prevalent. Some established research works have attempted to provide state-of-the-art reviews on modeling and analysis of rain attenuation in the context of extremely high frequencies. However, the existing review works conducted over three decades (1990 to 2022), have not adequately provided comprehensive taxonomies for each method of rain attenuation modeling to expose the trends and possible future research directions. Also, taxonomies of the methods of model validation and regional developmental efforts on rain attenuation modeling have not been explicitly highlighted in the literature. To address these gaps, this paper conducted an extensive literature survey on rain attenuation modeling, methods of analyses, and model validation techniques, leveraging the ITU-R regional categorizations. Specifically, taxonomies in different rain attenuation modeling and analysis areas are extensively discussed. Key findings from the detailed survey have shown that many open research questions, challenges, and applications could open up new research frontiers, leading to novel findings in rain attenuation. Finally, this study is expected to be reference material for the design and analysis of rain attenuation