Vehicular Channel Characterization in Urban Environment at 30 GHz considering Overtaking and Traffic Flow

To realize reliable and stable millimeter-wave (mmWave) vehicular wireless communication, the research of vehicular channel characteristics in the dense urban environment is becoming increasingly important. A comprehensive research on the channel characteristics for 30 GHz vehicular communication in the Beijing Central Business District (CBD) scenario is conducted in this paper. The self-developed high-performance ray-tracing (RT) simulator is employed to support intensive simulations. Based on simulation results, the effects of multiantenna and beam switching on the key channel parameters are analyzed, as well as the impact of different traffic flows. The results can provide theoretical and data support for the evaluation of vehicular channel characteristics and will help for the design of the vehicular communication system enabling future intelligent transportation.

A Simple Monopole Antenna with a Switchable Beam for 5G Millimeter-Wave Communication Systems

A simple and compact antenna with a switchable beam for millimeter-wave communication is proposed in this paper. The antenna has a planar structure, and the design evolution is discussed. The beam switching functionality was achieved by incorporating two PIN diodes in the ground plane of the antenna. By switching ON either of the PIN diodes, the inverted L-shaped stub becomes connected to the ground plane and behaves as a cavity, which causes the dispersion of the radiation pattern. Therefore, a wide-angle (±18∘) beam-switching property can be achieved using a simple and low-cost technique, without the necessity to implement additional conventional circuits. The proposed antenna is characterized by a good performance in terms of return loss, bandwidth, measured gain up to 7.95 dB, and radiation efficiency up to 84%, making it a proper candidate for IoT technology and millimeter-wave 5G devices.

Pattern Reconfigurable Antenna for VANET, Wi-Fi, and WiMAX Wireless Communication Systems

This work presents the design and analysis of a beam switching antenna for VANET, Wi-Fi, and WiMAX wireless communication systems. The proposed reconfigurable antenna is powered by a coaxial cable and consists of a circular patch, six fish-shaped radiating elements, and a circular planar ground. The antenna was constructed on a Rogers RT5880 substrate. Its dimensions are as follows: 0.81λ0 × 0.81λ0 × 0.03λ0. It performs six reconfigurable operating states, at the same frequency, by controlling the activation and deactivation of six PIN diodes to change the beam’s direction. A theoretical equivalent circuit model of the antenna is extracted. A progressive analysis of improving the antenna characteristic performances is provided. The bandwidth of the proposed antenna is 9.07% (measured), 9.62% (simulated), and 9.31% (theoretical). The designed antenna has a maximum gain of 9.57 dB for all pattern states and a superior efficiency ratio from 85% to 95% over the operating range (5.54 GHz–6.10 GHz). The proposed reconfigurable antenna is fabricated. Measured, simulated, and theoretical results are given and show good agreement, including reflection coefficient (S11) and radiation patterns.

A Location Management Strategy for Satellite Internet Constellation

Satellites are currently the most effective means to achieve seamless global coverage of the Internet. Due to the frequent beam switching caused by the high-speed movement of satellites, it is too expensive to directly apply the location management strategy in the terrestrial network to the satellite Internet constellation (SIC). To build a web browsing platform based on satellite Internet, it is necessary to display the location of satellites and terminals in real time. For this reason, this paper proposes the location management strategy of SIC. It uses the characteristics of large and periodic satellite beam coverage in a certain period of time, redesigns the location management database structure, location registration mechanism and call delivery mechanism, and analyses and simulates the bit cost of location management. The result proves that compared with the traditional strategy, this strategy greatly reduces the cost of SIC.