A novel mapping technique for ray tracer to system-level simulation

Simulations have become remarkably useful in evaluating the performance of new techniques and algorithms in communication networks. This is due to its comparative cost, time and complexity advantage over the analytical and field trial approaches. For large-scale networks, system-level simulators (SLS) are used to assess the performance of the systems. The SLS typically employs statistical channel models to characterize the propagation environment. However, the communication channels can be more accurately modeled using the deterministic ray tracing tools, though at the cost of higher complexity. In this work, we present a novel framework for a hybrid system that integrates both the ray tracer and the SLS. In the hybrid system, the channel strength in terms of the signal-to-noise ratio (SNR) is fed from the ray tracer to the SLS which then uses the values for further tasks such as resource allocation and the consequent performance evaluation. Using metrics such as user throughput and spectral efficiency, our results show that the hybrid system predicts the system performance more accurately than the baseline SLS without ray tracing. The hybrid system will thus facilitate the accurate assessment of the performance of next-generation wireless systems

Medium-Voltage DC-DC Converter Topologies for Electric Bus Fast Charging Stations: State-of-the-Art Review

With the expansion of E-mobility technology, the demand for Medium-Voltage (MV) Electric Buses (E-buses) charging infrastructure has significantly increased. In this regard, the effective connection of E-bus chargers to a medium voltage power grid is essential to provide fast charging and carry out multiple charging processes simultaneously. One of the main building blocks for E-bus charging is the DC-DC converter stage responsible for regulating the power flow and matching the different voltage and power levels. Accordingly, this paper presents a comprehensive review of DC-DC converter topologies applicable to MV E-bus fast charging. This review discusses and compares the basic isolated DC-DC converter topologies. In addition, the DC-DC converters are classified based on their conversion stages. Moreover, isolated DC-DC converter topologies applicable for MV E-bus fast charging applications, including Dual Active Bridge (DAB) modular-based structure converter and Modular Multilevel Converter (MMC)-based DAB, are discussed where the merits and demerits of each topology are highlighted. Moreover, this review illustrates how DAB converters are employed in different power level applications through the multimodule converter or the MMC-based DAB structure. Furthermore, the challenges and required features for MV DC-DC converter topologies are discussed.This work was supported in part by the National Priorities Research Program (NPRP) through the Qatar National Research Fund under Grant 10-0130-170286. Qatar National Library funded the publication of this article. The statements made herein are solely the responsibility of the authors