A Selective Downlink Scheduling Algorithm to Enhance Quality of VOD Services for WAVE Networks

The vehicular ad-hoc network (VANET) is a promising technology in near future. VANET allows vehicles to communicate with each other and with roadside units (RSUs). Wireless Access in Vehicular Environment (WAVE), defined by IEEE, provides the Internet connectivity for vehicles as well as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. RSUs can form a wireless mesh network (WMN) as a backbone infrastructure to enhance the performance of VANET. However, WAVE supports only one-hop communications for IP packets in VANET, and existing researches do not consider the compatibility between VANET and WMN infrastructure formed by RSUs. We propose the extended WMN (ExWMN) which has the feasibility to extend WMN to VANET domain. In ExWMN, the vehicles can send IP packets to an access router by using the multi-hop capability of WMN. ExWMN uses the addressing scheme of WMN for the extended VANET domain and exploits geographical routing protocols instead of existing routing protocols of WMN due to VANET characteristics such as mobility and dynamically changing network topologies. ExWMN supports the compatibility between the extended VANET and a WMN infrastructure due to RSUs, which provide a bridging function between them. This paper presents the architecture and the detailed procedures of the ExWMN.

Vehicular ad hoc networks (VANETS) are simply a collection of onboard units (OBUs) and roadside units (RSUs) that communicate using dedicated short-range communications (DSRC) utilizing 75 Mhz in 5.9 GHz frequency band for wireless access in vehicular environment (WAVE). The frequency channel layout of WAVE has been divided into seven channels, with one channel for service safety applications and the remaining for service non-safety applications. The nature of the VANET environment being dynamic, it is most likely that packet forwarding over varied time intervals may be disconnected, causing network delays. In such a case the message containing information needs to be with the current vehicle until a new intelligent node becomes active. Extensive studies have been conducted on the propagation of messages in vehicular networks. Although conventional methods are mainly focused on similar traffic, in this only high, low-density traffic is considered. The intelligent mobile node structure in NS-3 has been designed in such a way as to support 802.11 MAC with a single channel. However, this intelligent mobile node is not appropriate for WAVE multi-channel operation.

Proportional fair resource allocation in vehicle-to-infrastructure networks for drive-thru Internet applications

WAVE(Wireless Access in Vehicular Environments) designed for vehicle communication has the features of a short initial link, low latency and high mobility. The success of data transmission in WAVE is affected by the priority and size of data and how many nodes are transmitting the data. In this paper, we tested and analyzed how the success rate of data transmission of each node varies according to the number of nodes, priority and size of data in various cases. Based on the simulation results, it is possible to confirm the success rate of data transmission and delay time for each node and the entire channel, and it can be determined how channel resources should be efficiently used considering these results.

To improve the throughput performance of the Wireless Access in Vehicular Environment (WAVE) system, we propose a multi-channel MAC protocol that is able to adaptively adjust the intervals of Control Channel (CCH) and Service Channel (SCH) according to the probability distribution of the reservation time for service packet in CCH Interval. Numerical results show that our protocol can significantly improve the performance of WAVE system.

Recently, the IEEE 1609.4 Standard for Wireless Access in Vehicular Environments (WAVE) has been proposed to enhance the performance of vehicular networks with multi-channel operations that allow for the coexistence of safety-related and non-safety related vehicular applications. However, while the benefits of the multi-channel approach are clear, the impact of the IEEE 1609.4 channel scheduler on the performance of delay-constrained vehicular applications remains to be well explored by researchers. At present, the evaluation of 1609.4-based Vehicular Ad Hoc Networks (VANETs) constitutes an open issue due to the lack of simulation tools that can provide a complete modeling of the IEEE WAVE 802.11p/1609.4 stack. In this paper, we provide three key contributions pertaining to multi-channel VANETs. First, we describe our implementation of the IEEE 1609.4 protocol in the ns2 simulator, and we detail its current integration with the existing ns2 implementation of the 802.11p MAC protocol. Second, using our simulation model we propose an evaluation study of 1609.4-based VANETs, and we show that the tight channel synchronization issues foreseen by the protocol might have a dramatic impact on the performance of safety-related applications with strict delivery ratio and delay requirements. Third, we propose two new enhancements for the WAVE protocol stack to favor the dissemination of safety messages in multi-channel VANETs. The suggested algorithms are shown to greatly improve packet delivery ratio and delay of safety applications in single and multi-hop topologies, while preserving the synchronization scheme of the IEEE 1609.4 protocol.

The research of vehicular networks has been studied for many years. In actual life, there are a few implementations of V2X communication system, majority of them are extremely expensive. Most importantly, detailed insight implementation procedure hasn't been provided for researches. In this paper, an efficient V2X communication system based on the IEEE 802.11p/1609.X protocol stack, also known as the Wireless Access in Vehicular Environment (WAVE) standard has been designed. In this system, a Dedicated Short Range Communication (DSRC) unit using low-cost and commercial hardware which can support the vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications is developed. Some specific driver adjustments based on the IEEE 802.11a driver are taken to assure compliance with the IEEE 802.11p protocol. Besides, the development of networking layer protocol is accomplished based on IEEE 1609.3. Furthermore, three safety applications and a performance evaluation subsystem have been developed on this platform. The subsystem can test the comprehensive performance of the communication unit in terms of Packet Loss Rate (PLR), throughput and end-to-end delay. Meanwhile enormous experiments are conducted to evaluate the performance of the communication prototype and different scenarios were designed to validate the practical function of the safety applications.

Dedicated Short Range Communications (DSRC) is a wireless communication standard intended for high speed secure communication between vehicles and the infrastructure. In order to overcome the limitations that vehicular environment imposes such as high mobility, IEEE published the 802.11p amendment widely known as Wireless Access in Vehicular Environment (WAVE). To the best of our knowledge, most of the WAVE stack implementations and studies that are carried out till now are simulator based. This paper majorly focuses on the implementation of IEEE 1609 WAVE /DSRC stack on a Linux based system that forms the backbone of vehicular communication. It dives deep into the changes and the development of new modules that have to be made in Linux kernel to cater the need for vehicular communication. We also discuss in brief about the various challenges faced and design decisions that were made in this process. Finally, we conclude by depicting the performance of our developed stack in comparison with commercially available stack in terms of packet losses.

The current medium access control (MAC) protocol of the wireless access in vehicular environments (WAVE) system is based on IEEE 802.11 distributed coordination function (DCF) and enhanced distributed channel access (EDCA), which have drawbacks in supporting throughput-sensitive non-safety applications in vehicular ad-hoc network (VANET). In order to address the problem, we propose a novel MAC protocol, namely vehicular MESH network (VMESH), which is specifically designed for the control channel (CCH) and multiple service channels (SCHs) structure of WAVE. A synchronized and distributed beaconing scheme is employed in the VMESH protocol for the purposes of neighborhood awareness and dynamic resource reservation on SCHs. The advantages of the VMESH protocol in supporting the throughput-sensitive non-safety applications in VANET are shown through the theoretical analysis comparing to the current WAVE MAC.

Recent V2X communication technology provides safety and service information in real time for autonomous driving. It has been researched more improved performance rather than legacy wireless access in vehicular environments (WAVE) through high data rate and low packet latency. However, quality of service(QoS) cannot currently be guaranteed, because original physical and medium access control(MAC) layer have been optimized for low mobility. This paper focuses on the implementation of enhanced MAC layer of WAVE and proposes a new channel access method for QoS.

Wireless Access in Vehicular Environments (WAVE) protocol stack is the most important protocol used to allocate spectrum for vehicular communication. The capabilities of WAVE to provide reliable exchange of safety information are questionable. In a previous work, we suggested a system that employs cognitive networks principles to increase the spectrum allocated to the control channel (CCH) by the IEEE 802.11p amendment, where all safety information is transmitted. However, the decision making process implemented in that work does not differentiate between contention levels and does not relate precisely the measured contention to the amount of needed spectrum, which leads to an inefficient utilization of the white spectrum. In order to assign the minimum necessary additional bandwidth to relieve the contention, we suggest in this paper a new system that quantifies contention into multiple levels of severity based on Fuzzy Logic and maps additional spectrum correspondingly. Simulations show the effectiveness of the system in allocating the minimum needed bandwidth to relieve contention, without affecting other QoS parameters such as delay and number of untransmitted packets.

Dedicated short range communication (DSRC) is the key component in intelligent transportation systems (ITS). The goal of this technology is to help driver and passengers getting multimedia services via wireless communication equipment during the movement of vehicle, so as to improve the traffic safety and enhance the transportation efficiency. The paper is focus on the DSRC baseband technical analysis and the application development. Based on the WLAN 802.11a architecture, we develop a new adaptive channel estimation algorithm that uses two kinds of feedback tracking and pilot aid to enhance wireless access ability in vehicular environments.

This paper presents a seamless handover scheme for the IEEE WAVE (Wireless Access for Vehicular Environment) networks based on proactive caching of data packets. In the proposed scheme an On-broad Unit (OBU) uses the IEEE 802.11 disassociation message to inform the old Road-Side Unit (RSU) about its departure from the coverage area such that the old RSU can forward the buffered packets to candidate RSUs for caching. A multicast-based forwarding scheme is used to forward the buffered packets when there are multiple candidate new RSUs around crossroads or diverging roadways. One of the candidate RSUs becomes the new RSU which transmits the cached packets to the OBU upon its entry into the radio coverage. The IEEE 802.11f Move-notify message is used by the new RSU to request the rest of candidate RSUs to purge the cached packets in order to prevent the waste of radio resource. Simulation results show the proposed scheme outperforms a simple multicast-based scheme.

IEEE 802.11p Wireless Access for Vehicular Environments (WAVE) is the approved communication protocol for Vehicular Ad-hoc Networks (VANETs) and Intelligent Transportation System (ITS) applications. WAVE offers service differentiation by prioritizing packets based on an application's requested QoS. These priorities are static and do not account for network load or vehicle's context severity. In this paper, we propose a novel opportunistic service reprioritization (OSR) technique for IEEE 802.11p (WAVE). It dynamically promotes and/or demotes vehicle's load to different access categories, by taking into account the vehicle's context severity and network link layer bounds. We show the feasibility of our approach by formulating the opportunistic service reprioritization technique as a Linear Programming (LP) problem and solve it to guarantee optimal QoS with respect to severity for all access categories. We compare our opportunistic service reprioritization technique with WAVE and show significant improvement. The weighted average delay in OSR outperforms classical WAVE, on average by 90%.

Recently, the number of drones for personal leisure as well as Unmanned Aerial Vehicles (UAVs) for such as military, commercial, agricultural, disaster response is increasing rapidly. When a large number of UAVs fly simultaneously in airspace, collision problems between UAVs can occur, which is likely to lead directly to human accidents or economic loss. Accordingly, there are growing needs for UAS Traffic Management (UTM) systems. In this phenomenon, various communication protocols for UTM are emerging. In this paper, especially, the application of UTM system based on Wireless Access in Vehicular Environment (WAVE) protocol is introduced as one of most efficient and stable protocols in environments with high-speed mobility and dynamic changing topology. Furthermore, we design a network architecture that supports direct communication among UAVs as well as UAV and ground station within the UTM framework. By applying WAVE protocol in the UTM system, it is possible to transmit messages promptly and accurately to prevent collision in the event of an emergency, and to configure the UTM system to manage all UAVs by applying a WAVE-based ad-hoc network.