The design of an eight-element H-shaped dual-band multiple-input multiple-output (MIMO) antenna system for sub-6 GHz fifth-generation (5G) smartphone applications is presented in this work. The radiating elements are designed on the side edge frame of the smartphone, placed on both sides of the main printed circuit board (PCB). Each side edge consists of four radiating elements, which ensures low mutual coupling between antenna elements. The total size of the main PCB is 150×75 mm 2 , while the size of the side edge frame is 150×7 mm 2 . A single antenna consists of an H-shaped radiating element fed using a 50Ω microstrip feeding line designed on the main board of the smartphone. The results show that, according to -6 dB impedance bandwidth criteria, the designed MIMO antenna radiates at two different frequency ranges within the allocated FCC 5G spectrums, i.e., 3.1-3.78 GHz and 5.43-6.21 GHz with 680 MHz and 780 MHz bandwidths, respectively. It is also observed that the antenna elements are able to provide spatial and pattern diversity for both the frequency bands. Furthermore, an isolation of >12 dB is observed between any two given radiating elements. Various MIMO key performance parameters are evaluated, such as channel capacity (CC), envelope correlation coefficient (ECC), and diversity gain (DG). A prototype is fabricated and measured, and it is found that the measured and simulated results are in good agreement. Based on performance attributes, it can be said that the proposed MIMO system may find its application in 5G communication systems.

Uncoordinated traffic flows at the traditional roundabouts, especially with a small circumference and fewer lanes, are often heavily affected by congestion, which escalates fuel consumption, CO2 emissions, idling, and travel delay. An intriguing way to mitigate such uncoordinated flows at junctions would be facilitated through optimal traffic signalization. For this purpose, this paper presents a novel holistic Three-Leg Signalized Roundabout (TLSR) model based on two signalized stop lines (2SL). The first stop line is placed at each entry curve of a roundabout with effectual lane markings as usual. Hereafter, the second stop line is set exclusively in the circulatory roadway to improve left-turning mobility with an additional “short-lane model” to deal with heavy traffic, following specific patterns for smooth vehicle merging. The capacity and optimal signal cycle relationships are derived to evaluate the performance of the proposed TLSR-2SL, considering the internal space constraints of the roundabout. Under the various scenarios, the parameters’ sensitivity tests demonstrate that signal cycle and central radius play a significant role in enhancing the roundabout’s operational performance. From the executed simulation, the proposed framework improves the traffic flow by 15% and controls the relative error within 10% compared to benchmark methods.

This paper presents a novel holistic T-shape roundabout coordination system (TCS) that addresses the connected and automated vehicles (CAVs) flow in a typically isolated T-shape roundabout. The TCS optimizes the states of each approaching vehicle in a receding horizon control framework that aims to minimize the total crossing time, considering the vehicles' dynamic states. The control method ensures the comfortable crossing of each vehicle by retaining the basic features of a traditional traffic control management system. The optimal states are broadcasted ahead by TCS, which enables the CAVs to form a cluster and tune their speed in order to cross the roundabout with minimum stop-delay. We evaluate the effectiveness of the proposed TCS method under the various traffic flow demand. From the executed simulation, it is observed that the optimization process usually improves the average velocity, and reduces both the traffic density and vehicles' idling situation. As a consequence, the fuel consumption of each vehicle around the roundabout is also decreased. These outputs are compared with the traditional method, showing that the overall flow performance significantly improves in the case of the proposed scheme, and vehicles have rapid optimization for a smooth crossing.INDEX TERMS bi-level coordination, CAVs clustering, connected and automated vehicles, optimization, receding horizon control, T-roundabout,

In recent years, frequency selective surfaces (FSSs) have been extensively investigated in terms of their design and practical applications at microwave and optical frequencies. This study proposes a new design of a FSS layer, which is directly placed over the surface of an antenna to enhance its characteristics such as directivity, frequency selectivity, radiation efficiency, and gain. In the proposed design, two different substrates are used to analyze the improved performance of the FSS layer. For this purpose, FR-4 Epoxy and Duroid 5880 are used for cost effectiveness and to achieve the optimized performance of the antenna. The simulated and measured results are in good agreement, indicating the enhanced performance of antenna for WLAN and WiMAX applications. Finally, it is concluded that the proposed FSS layer ensures the best possible results of the filtering response as the first null gives divergence of more than 10 dB with its peak value layer.

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