One of the most important parameters of the performance of grounding systems is the soil resistivity. As generally known, the soil resistivity changes seasonally, hence the performance of grounding systems, at DC and under high impulse conditions. This paper presents the performance of grounding systems with two different configurations. Field experiments were set up to study the characteristics of the grounding systems seasonally at power frequency and under high impulse conditions. A review of field testing on practical grounding systems was also presented. It was found that the soil resistivity, RDC and impulse characteristics of grounding systems were improved over time, and the improvement was higher for electrodes that have more contact with the soils.
This article introduces an efficient analysis of indoor 4.5 GHz radio wave propagation by using a proposed three-dimensional (3-D) ray-tracing (RT) modeling and measurement. The attractive facilities of this frequency band have significantly increased in indoor radio wave communication systems. Radio propagation predictions by simulation method based on a site-specific model, such as RT is widely used to categorize radio wave channels. Although practical measurement provides accurate results, it still needs a considerable amount of resources. Hence, a computerized simulation tool would be a good solution to categorize the wireless channels. The simulation has been performed with an in-house developed software tool. Here, the 3-D shooting bouncing ray tracing (SBRT) and the proposed 3-D ray tracing simulation have been performed separately on a specific layout where the measurement is done. Several comparisons have been performed on the results of the measurement: the proposed method, and the existing SBRT method simulation with respect to received signal strength indication (RSSI) and path loss (PL). The comparative results demonstrate that the RSSI and the PL of proposed RT have better agreements with measurement than with those from the conventional SBRT outputs.Electronics 2019, 8, 750 2 of 17 of transmitter, and the propagation environment [4]. It is also challenging to optimize the actual position of the transmitter (Tx) by measurement to ensure acceptable system performance. Therefore, radio-propagation using a simulation tool for the indoor environment based on RSSI and PL has become a significant research tool [5].Weather conditions-such as floods, rains, clouds, or snowfall-have no effect on the indoor radio propagation; however, it can be influenced by the interior walls, furniture, doors, windows, and other household objects. These influences need to be considered for better indoor radio wave propagation modeling. Therefore, the indoor scenario has these objects, with Tx waves reaching the receiver (Rx) through multipath channels [6].Although practical measurement enables actual assessment of onsite performance, it requires a sizable amount of resources and effort. On the other hand, software simulation tools are easy to use and are an inexpensive way to obtain accurate results [7]. Nowadays, many researchers recommend the use of the RT technique for radio propagation prediction modeling [8].Based on the fundamental geometric optics (GO) theory and uniform theory of diffraction (UTD) principles, RT is extensively used in radio wave modeling, and is widely used in indoor WCS [9]. The RT full cycle has three steps: ray launching (RL), ray path sensing, and ray capturing by receivers [10]. The RL is the method of propagating straight rays in all directions in space. Normally, the rays are launched from the source of a Tx to the destination Rx by following the principle of GO and UTD. The complete ray path is traced, bearing the additional propagation features of transmission, reflection, and diffraction [...
In small spaces in which typical cell towers cannot be constructed, distributed antenna systems (DASs) are the preferable approach for increasing network coverage, as they are a superior solution for congested, high-volume areas. However, due to their high cost and complexity in backhaul routing, reconfigurable intelligent surfaces (RISs) are a promising solution to overcome the major drawbacks of DAS systems while improving network coverage. Thus, this work investigated a correlation of execution in an RIS-aided system cell framework and DAS-aided system cell framework where a simple and precise structure for the performance measurement of area spectral efficiency (ASE) and energy efficiency (EE) under realistic channel presumptions was introduced. The analysis started with the downlink ergodic capacity with regards to the RIS framework and DAS framework under a generalized Nakagami-m fading channel with the presence of path-loss attenuation and interference from co-channel base stations (BSs), and was simplified further by utilizing a moment-generating function (MGF)-based approach. From the computed expression, the effects of traffic activity, EE and ASE were derived and analyzed for both systems in the presence of co-channel interference. The results were then verified by comparing them with Monte Carlo simulations, and the findings show that the two outcomes generally match. Based on these, it is demonstrated that the ASE performance of the RIS-assisted system in various traffic activity conditions outperforms the DAS-aided system; however, in high signal-to-noise (SNR) regions with full traffic activity, the ASEs are highest for both systems; by only 0.005 bits/s/Hz/km2.
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