يوسف محسن حسن

This work presents a compact, low-cost hexa-band microstrip antenna for Internet of Things (IoT) applications. The proposed hexa-band antenna is composed of simple six-λ/4 resonators to generate six resonant frequencies: GSM 1.84 GHz (1.8 –1.89 GHz), Bluetooth 2.31 GHz (2.25 –2.375 GHz), WiMAX 3.3 GHz (3.16 –3.47 GHz), WiFi 4.63 GHz (4.34 –5 GHz), upper WLAN 6.1 GHz (5.8 –6.91 GHz), and X-band 9.26 GHz (8.87 –9.83 GHz). The proposed hexa-band antenna is fabricated using FR4 substrate with (23 × 20 × 1.6) mm3 dimensions, and its measured results are presented to validate the simulated results. Results from simulations and measurements are used to examine the radiation properties, including radiation patterns, gain, efficiency, VSWR, and reflection coefficient. The proposed hexa-band antenna has a miniaturized size and good radiation performance.

The recent advances in the technology of smart devices caused a tremendous increase in wireless traffic in conventional cellular networks, thus leading to overloading the base station, and hence delaying the response to users’ requests. To overcome this, Device to Device (D2D) communication has been proposed recently to alleviate the traffic congestion at the base station (BS) by establishing a direct link between users. However, deciding whether a communication should be performed directly via D2D mode or via the base station is considered one of the challenges of applying such a method. Therefore, a mode selection based model was presented in this paper. The method depends on the probability of a user’s proximity close to 1.0. Furthermore, the proposed method also takes into account the interference with both; other cellular communication and D2D communication. The simulation results showed that a significant reduction in the delay can be achieved when responding to user requests after using the proposed model selection method. The increase in frequency reuse within the cell is considered as the main reason behind this behavior. Also, for a more simplified and less complex model selection method, it is more appropriate to apply the proposed model selection method to only the cell edges. © 2020 Institute of Physics Publishing. All rights reserved.