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Weighted-Polarization MRC Adaptive Vehicular Antenna for Secure Communication in Rollover Accident
Abstract
In this paper, we investigate the signal bit error rate (BER) characteristics of a vehicle-borne weighted polarization maximum ratio combining adaptive array antenna for secure communications. The array comprises orthogonally arranged dipole elements, which are combined using weight functions determined by the cross-polarization power ratio in the propagation environment and the angle of inclination of the antenna. The experimental results show that the required signal-to-noise ratio for the proposed antenna to achieve the prescribed BER is lower than that for a conventional dipole array even in vehicle rollover accidents.
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This paper presents a multiple-input, multiple-output (MIMO) antenna system with the ability to perform full-azimuth beam steering, and with the aim of realizing greater than 20 Gbps vehicular communications. The MIMO antenna described in this paper comprises 64 elements arranged in a daisy chain array structure, where 32 subarrays are formed by pairing elements in each subarray; the antenna yields 32 independent subchannels for MIMO transmission, and covers all communication targets regardless of their position relative to the array. Analytical results reveal that the proposed antenna system can provide a channel capacity of more than 200 bits/s/Hz at a signal-to-noise power ratio (SNR) of 30 dB over the whole azimuth, which is equivalent to 20 Gbps for a bandwidth of 100 MHz. This remarkably high channel capacity is shown to be due to two significant factors; the improved directivity created by the optimum in-phase excitation and the low correlation between the subarrays due to the orthogonal alignment of the array with respect to the incident waves. Over-the-air (OTA) experiments confirm the increase in channel capacity; the proposed antenna can maintain a constant transmission rate over all azimuth angles.
This paper proposes a vehicular communication system that can achieve multi-Gbps data rate transmission for train and car applications. Employing a millimeter wave (mmWave) frequency band around 25 GHz, the proposed system provides mobile backhaul connectivity for vehicle user equipments (UEs). In order to support a very high data rate with such a high carrier frequency while guaranteeing sufficient robustness against high mobility-related behaviors such as fast channel variation and unstable handover, we employ a relaying network architecture consisting of a backhaul link to a vehicle UE and an in-vehicle access link. Based on that, we provide a set of fundamental design elements including numerology, frame structure, reference signal, multi-antenna scheme, and handover. We then validate the proposed vehicular communication system by implementing an experimental testbed consisting of baseband modem, RF frontend, and array antenna units, and by performing field trials in an actual subway tunnel and urban road environments. Experimental validation results reveal that providing multi-Gbps backhaul transmission is possible and worthwhile for both train and car scenarios.
Autonomous driving is delightedly an innovative and revolutionary paradigm for future intelligent transport systems (ITS). To be fully-functional and efficient, vehicles will use hundreds of sensors and generate terabytes of data that will be used and shared for safety, infotainment and allied services. Communication among vehicles or between vehicle and infrastructure thus requires data rate, latency and reliability far beyond what the legacy dedicated short-range communication (DSRC) and Long Term Evolution- Advanced (LTE-A) systems can support. In this work, we motivate the use of millimetre-wave (mmWave) massive multiple-input multiple-output (MIMO) technology to facilitate gigabits-per-second (Gbps) communication for cellular vehicle-to-infrastructure (C-V2I) scenarios. As a fundamental component, we characterize the mmWave massive MIMO vehicular channel using metrics such as path loss, root-mean-square delay spread, Rician K-factor, cluster and ray distribution, power delay profile, channel rank and condition number as well as data rate. We compare the mmWave performance with the DSRC and LTE-A capabilities, and offer useful insights on vehicular channels. Our results show that mmWave massive MIMO can deliver Gbps data rates for next-generation vehicular networks.
Device-to-device (D2D) is increasingly becoming a prominent technology within the 5G story, portrayed as a means of offloading traffic from the core network. The ever increasing demand for vehicular traffic consumption is providing the impetus for a new architectural design that can harness the benefits of D2D for vehicular users, taking a step toward offloading vehicular traffic from the core network. We propose the notion of extending D2D for vehicular scenarios with the potential to coordinate vehicular traffic using the LTE band. Furthermore, we then extend this approach by investigating cognitive radio in synergy with a geo-location database, to exploit white spaces as a means of further offloading vehicular users. Our simulation results have shown that our approach can outperform the legacy IEEE 802.11p in terms of delay.
This paper presents a calibration method for measuring the channel capacity using a three-dimensional multiple-input multiple-output (MIMO) Over-The-Air (OTA) apparatus. The reference level is calibrated to establish the Gaussian angular power spectra in elevation in consideration of various power losses that exist in the fading emulator. The measured results of MIMO channel capacity agree well with the analytical outcomes calculated by Monte Carlo simulation, demonstrating that the proposed calibration method gives a high degree of accuracy for measuring the channel capacity using the three-dimensional MIMO-OTA apparatus.
In this paper, we present a weighted-polarization wearable multiple-input multiple-output (MIMO) antenna that is based on radiofrequency (RF) signal processing to realize ultra-high-speed and highcapacity mobile communications. The proposed antenna is comprised of three orthogonal dipoles, two of which can be selected according to a weight function in different usage scenarios. The weight function is determined by considering the variation in the cross-polarization power ratio (XPR) and the antenna inclination angle which depend on the radiopropagation environment and human motion. To confirm the suitability of the proposed antenna, we perform preliminary experiments to evaluate the channel capacity of a weighted-polarization wearable MIMO antenna with an arm-swinging dynamic phantom. The measured and analytical results are in good agreement, which verifies the effectiveness of the proposed antenna. We demonstrate that the proposed antenna is suitable for realizing gigabit mobile communications in future wearable MIMO applications. Copyright © 2016 The Institute of Electronics, Information and Communication Engineers.
This paper examines the performance of the adaptive array antennas used in digital handset systems by studying the minimum mean square error (MMSE) algorithm at 2 GHz. The array is comprised of multiple quarter-wavelength monopole antennas and planar inverted-F antennas (PIFAs). By calculating the spatial correlation between two different directions, we describe how significant enhancement in the capability of reducing interference signals can be achieved, even when the handset is being held in the vicinity of a human operator in the talking position. Secondly, a computer simulation has been carried out under a flat Rayleigh fading environment with multiple cochannel interference signals, in which the average bit error rate (BER) of the handset adaptive array antenna has been characterized for the coherent detection of phase-shift keyed (PSK) signals. The performance of the handset adaptive array is compared to that of an adaptive array comprising plural parallel half-wavelength dipole antennas that are one half-wavelength apart. The performance was also evaluated with regard to the distance between the handset and the human head for different unequal median values and fading correlations of the received signals. The study has revealed that the adaptive array under consideration has substantial potential, not only to reduce the relative power of interference signals, but also to combat multipath fading of the desired signal by using the spatial diversity function of the MMSE, even in close proximity to a human operator.
Rollover-resistant vehicular MRC adaptive array with weighted polarization combining
- T Oda
- H Tanaka
- K Honda
- K Ogawa