Wireless Access In The Vehicular Environment Research Articles

Multiband bandpass filter with asymmetric dual‐band response based on metacell

AbstractThe impressive growth in present‐day wireless communication systems demands compact, low‐power, cost‐effective, planar multiband microwave devices to increase the speed of communication and reduce hardware requirements, which subsequently reduce the power requirement of the system. Accordingly, this article aims to design a multiband microstrip bandpass filter with asymmetric dual‐band response based on metacell. The proposed filter is designed for wide and narrow dual‐band responses with fractional bandwidths of 72% and 2.6%, respectively. For the first time in this article, a new application of metacell in the design of dual‐band filters is discussed. A folded asymmetric step‐impedance resonator and a novel metacell structure—Dual loop split ring resonators are used to obtain wideband and dual‐band responses, respectively. The proposed work discusses the design methodology, and analysis of metacell structure based on a quasistatic model and compares simulation results with experimental results. The proposed dual‐band filter presents an insertion loss (S21) of less than 1 dB and input reflection coefficient (S11) greater than 10 dB in both passbands centered at 3.3 and 5.7 GHz. The designed filter is suitable for wireless communication applications—Wireless Access in the Vehicular Environment.

Design and Realization of a Frequency Reconfigurable Antenna with Wide, Dual, and Single-Band Operations for Compact Sized Wireless Applications

This paper presents a compact and simple reconfigurable antenna with wide-band, dual-band, and single-band operating modes. Initially, a co-planar waveguide-fed triangular monopole antenna is obtained with a wide operational frequency band ranging from 4.0 GHz to 7.8 GHz. Then, two additional stubs are connected to the triangular monopole through two p-i-n diodes. By electrically switching these p-i-n diodes ON and OFF, different operating frequency bands can be attained. When turning ON only one diode, the antenna offers dual-band operations of 3.3–4.2 GHz and 5.8–7.2 GHz. Meanwhile, the antenna with single-band operation from 3.3 GHz to 4.2 GHz can be realized when both of the p-i-n diodes are switched to ON states. The proposed compact size antenna with dimensions of 0.27λ0 × 0.16λ0 × 0.017λ0 at the lower operating frequency (3.3 GHz) can be used for several wireless applications such as worldwide interoperability for microwave access (WiMAX), wireless access in the vehicular environment (WAVE), and wireless local area network (WLAN). A comparative analysis with state-of-the-art works exhibits that the presented design possesses advantages of compact size and multiple operating modes.

A Platoon-Centric Multi-Channel Access Scheme for Hybrid Traffic

Self-driving technology has made great advancements with the help of artificial intelligence and intelligent transportation system. Recent studies have shown that traffic efficiency and safety of autonomous vehicles can be further improved by autonomous platooning based on vehicular ad hoc networks (VANETs). However, hybrid traffic where autonomous platoons (APs) and individual human driven-vehicles (HDVs) co-exists is seldom considered. Wireless Access in the Vehicular Environment (WAVE) is the de facto wireless protocol for VANETs. WAVE has provided one control channel (CCH) and six service channels (SCHs). The multi-channel access scheme should be jointly designed along with the CCH communication protocol. To design a reliable and efficient communication protocol for hybrid traffic, we propose a platoon-centric multi-channel access scheme based on the reliable broadcast. The reliable broadcast scheme utilizes an enhanced RTS/CTS mechanism designed for multicast communications. A broadcast frequency control mechanism is proposed to balance CCH access intervals. Our scheme can improve the reliability of CCH communication and increase SCH utilization with minimal overhead. Analysis and simulation results demonstrate the superiority of the proposed mechanism.

A Fully Integrated Shark-Fin Antenna for MIMO-LTE, GPS, WLAN, and WAVE Applications

In this study, a three-dimensional compact antenna solution for the automotive industry is proposed. The antenna solution is designed to fit in a shark-fin case and is easily fabricated from a printed circuit board and a metal sheet with low-cost process and materials. The antenna solution covers Long Term Evolution (LTE), GPS, WLAN, and Wireless Access in the Vehicular Environment (WAVE) bands (850 MHz, 1575 MHz, 2.4 GHz, and 5.9 GHz, respectively). The planar inverted-F antennas are used as multiple-input-multiple-output antennas for the LTE band due to their low-profile structure. Modified planar monopoles are used to obtain omnidirectional radiation patterns for WLAN and WAVE bands. Antenna characteristics such as return loss, isolation, and radiation pattern have been simulated and measured to confirm the possibility for use in automotive applications.

V2V QoS Guaranteed Channel Access in IEEE 802.11p VANETs

IEEE 802.11p Wireless Access in the Vehicular Environment (WAVE) has been serving as the de facto wireless protocol for a Vehicular Ad hoc Network (VANET) with the explosive growth of vehicular applications. These applications require guaranteed Quality-of-Service (QoS). However, the fundamental channel access mechanism of WAVE, Enhanced Distributed Channel Access (EDCA), is not able to provide guaranteed QoS due to the unpredictable random access. To remedy this problem, we propose a novel channel access scheme, called Earliest Deadline First based Carrier Sense Multiple Access (EDF-CSMA). EDF-CSMA based on EDCA dynamically adjusts the priority of real-time streaming to avoid collision and introduces an admission control policy according to time constraints to provide guaranteed QoS in multi-channel environments. An analytical model is carried out to study and compare the channel utilization of EDF-CSMA and QoS-aware Hybrid Coordination Function (HCF) controlled channel access (HCCA) method. The result shows that 60 percent of channel utilization is improved by EDF-CSMA. Additionally, real video-based simulations are conducted to evaluate the performance of EDF-CSMA and the existing EDCA method. The results show that EDF-CSMA reaches better QoS support than EDCA while maintaining efficient channel utilization.

Efficient Channel Management Mechanism to Enhance Channel Utilization for Sensing Data Delivery in Vehicular Ad Hoc Networks

IEEE 1609.4 defines MAC layer implementation in a vehicular ad hoc network (VANET). In IEEE 1609.4 multichannel operation, the control channel interval (CCHI) and the service channel interval (SCHI) are defined such that service channels cannot be utilized during the CCHI, and vice versa, which leads to poor utilization of scarce spectrum resources. In this paper, we propose a multi-schedule-based channel switching mechanism to improve channel utilization and uniformly distribute channel load. In our proposed mechanism, four schedules are defined to switch between the control channel and service channels. Therefore, service channels can be utilized during the CCHI, and the control channel can be utilized during the SCHI. Moreover, control channel load is distributed throughout the whole sync interval. We compared our proposed MAC protocol with IEEE802.11p for wireless access in the vehicular environment using the OMNET++ 4.5 network simulator. In the simulation results, we determined that utilization of the service channel increased and contention on the control channel was reduced, compared with the legacy standard, especially in slow motion and high-density VANETs.

Erratum: Development of dual-band microstrip patch antenna for WLAN/MIMO/WiMAX/AMSAT/WAVE applications

The present work represents a dual-band microstrip-fed patch antenna in which the radiating structure is formed with a pair of inverted L-shape patches and ground plane is being modified to a -shape. Both the radiating patch and modified ground plane are perfect electric conductors. The patch is printed on a readily available Epoxy Glass (FR-4) substrate with thickness 1.6 mm, relative permittivity 4.4, and loss tangent 0.0024. The proposed microstrip patch antenna (MPA) design is capable of generating two distinct operating bands with 10-dB return loss as follows 3.34–3.54 GHz and 4.90–6.26 GHz with adequate bandwidth of 200 MHz and 1.36 GHz, respectively. The impedance bandwidths are wide enough to cover the required bandwidths of 3.3–3.5 GHz, 5.15–5.35 GHz, 5.725–5.825 GHz for wireless local area network, 3.3–3.5 GHz for multiple input multiple output, 5.25–5.85 GHz for world-wide interoperability for microwave access, 5.650–5.670 GHz for uplinks and 5.830–5.850 GHz for downlinks of Amateur Satellite, and 5.9 GHz wireless access in the vehicular environment (WAVE-IEEE 802.11p). Proposed MPA was simulated using Computer Simulation Technology Microwave Studio V9 based on the finite integration technique with perfect boundary approximation and effect of using different substrate materials was studied. Finally, the proposed antenna with optimized parameters was fabricated and some performance measurements were taken to validate against simulation results. The design procedure to achieve the required performance are presented and discussed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:988–993, 2014; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.28206. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1965–1970, 2014

QoE-Driven User-Centric VoD Services in Urban Multihomed P2P-Based Vehicular Networks

Recently, many cities around the world have witnessed large-scale deployment of terrestrial broadcasting mobile television (TV) to vehicles. This service is similar to the cable or satellite TV already in the home, and user-centric interactive mobile Video-on-Demand (VoD) over urban vehicular networks is in fact expected. However, providing this new service with focus on user Quality of Experience (QoE) constitutes a significant challenge. This paper introduces a QoE-driven User-centric solution for VoD services in urban vehicular network environments (QUVoD). QUVoD relies on a multihomed hierarchical peer-to-peer (P2P) and vehicular ad-hoc network (VANET) architecture. Vehicles construct a low-layer VANET via Wireless Access in the Vehicular Environment interfaces; they also form an upper layer P2P Chord overlay on top of a cellular network via Fourth-Generation (4G) interfaces. A novel grouping-based storage strategy that uniformly distributes the video segments along the Chord overlay is proposed, reducing segment seeking traffic while also enabling load balancing. A novel segment seeking and multipath delivery scheme that achieves high lookup success rate and very good video data delivery efficiency is also introduced, which achieves high lookup success rate and very good video data delivery efficiency. Furthermore, a new speculation-based prefetching strategy is proposed, which analyses users' interactive viewing behavior and, by estimating video segment playback order, employs prefetching of the expected segments, smoothening the video playback. Simulation results show how QUVoD is a highly efficient user-centric mobile VoD solution in urban vehicular networks in comparison with existing state-of-the-art solutions.

Performance Evaluation of IEEE 1609 WAVE for Vehicular Communications

In IEEE 1609, it uses IEEE 802.11 Enhanced Distributed Channel Access (EDCA) mechanism to access the channel. IEEE 802.11 EDCA is a new wireless technology for wireless access in the vehicular environment (WAVE). It defines a new supplement to the existing IEEE 802.11 MAC protocol. In IEEE 802.11 EDCA, the aim is providing a QoS support. While the system serves different access categories (ACs), EDCA does not perform well under high load conditions. In order to improve the efficiency, we pay attention to the EDCA with transmit opportunity (TXOP) mechanism. We first proposed a Markov chain model and studied the behavior. We extend the model to support IEEE 802.11 EDCA and presented a more accurate analysis under nonideal channel environment. We also compared it with that without TXOP mechanism under channel error environment.

An approximation analysis for safety messages transmission in vehicle-to-vehicle WAVE networks

Wireless Access in the Vehicular Environment (WAVE) specification defines the WAVE Short Message Protocol (WSMP) for delivering WAVE Short Messages (WSMs). In the multihop transmission, WSMs are first received and stored in queues and then forwarded to the next hop. Unfortunately, WSMP does not specify any mechanism to avoid the messages loss resulted from queueing overflow. In this paper, a dual threshold-based queueing management which adjusts the message accepting rate upon the current queue length is proposed. The multihop transmission can be modeled as a tandem queueing network, and a discrete time Markov chain (DTMC) can be applied to evaluate the proposed queueing management. Since the computational complexity increases with the number of hops, an approximation approach to resolve DTMC model is also presented. Simulation results demonstrate the accuracy of approximation and the effectiveness of the proposed queueing management.

A compact low-profile dual-band antenna for WLAN and WAVE applications

A compact and low-profile patch antenna with a simple structure is presented for the wireless local-area network (WLAN) and the wireless access in the vehicular environment (WAVE) applications. The proposed antenna with an overall size of only 23mm×25mm is fed by a coplanar waveguide (CPW), and yields 10-dB impedance bandwidths of about 250MHz centered at 2.44GHz and of about 22% ranging from 5.13 to 6.38GHz suitable for the WLAN 2.4/5.2/5.8GHz and the WAVE 5.9GHz (IEEE 802.11p) applications. Also, good dipole-like patterns and high average antenna gain of ≥2.3dBi over the operating bands have been obtained. In this design, resonance can be effectively controlled by simply tuning the shaped slots on the patch. Mechanism of mode excitations and effect of the added slot's length on resonance for the proposed antenna are examined and discussed in detail. The experimental results have validated the proposed design as useful for modern mobile communication.

Enhancing IEEE 802.11p/WAVE to provide infotainment applications in VANETs

IEEE 802.11p/WAVE (Wireless Access for Vehicular Environment) is the emerging standard to enable wireless access in the vehicular environment. Most of the research contributions in this area has focused on safety-related applications, while comfort and information/entertainment applications (such as on board Internet access, point-of-interest notification, e-map download) have been considered only recently. Notwithstanding, the user interest in this kind of applications is expected to become a big market driver in a near future. In this paper, an extension to IEEE 802.11p is proposed that is compliant with the multi-channel operation of the WAVE architecture and targets at the support of non-safety applications, while preserving the delivery of safety services. The proposed W-HCF (WAVE-based Hybrid Coordination Function) protocol leverages controlled access capabilities on top of the basic contention-based access of the IEEE 802.11p; it exploits vehicles’ position information and coordination among WAVE providers in order to improve performances of delay-constrained and loss-sensitive non-safety applications.