scholarly journals A hybrid access method for broadcasting of safety messages in IEEE 802.11p VANETs

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Xiaoying Lei ◽  
Xiangjin Chen ◽  
Seung Hyong Rhee
Keyword(s):  
Access Control ◽  
Multiple Access ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Ieee 802.11P ◽  
Media Access Control ◽  
Access Method ◽  
Safety Message ◽  
Hybrid Access

AbstractVehicular Ad-hoc Networks (VANETs) can improve the road safety by transmitting safety-critical messages such as beacons and emergency messages. IEEE 802.11p VANETs have adopted the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism for the multiple access control. The 802.11p media access control (MAC) protocol, however, can not guarantee the reliability of broadcasting data, since the reception of transmitted messages are not acknowledged. Moreover, the backoff scheme of the 802.11p MAC utilizes a fixed-size contention window for safety message broadcasting, which causes high collision probabilities especially in dense environments. In order to improve such drawbacks, we propose a hybrid access method as follows: Nodes are equipped to reserve time slots for the next round of broadcasting, while unoccupied time slots are preserved for those which have emergency needs. In addition, implicit feedbacks are enabled for detecting collisions incurred during random channel accesses in preserved time slots. We devise a mathematical model which optimally controls the parameters of our scheme while minimizes the cost caused by idle channels and collisions. Extensive simulations show that our mechanism can remarkably improve the performance of VANETs in broadcasting of the safety messages.

scholarly journals Time Slot Utilization for Efficient Multi-Channel MAC Protocol in VANETs

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3028 ◽  
Author(s):  
VanDung Nguyen ◽  
Tran Anh Khoa ◽  
Thant Zin Oo ◽  
Nguyen H. Tran ◽  
Choong Seon Hong ◽  
...  
Keyword(s):  
Multiple Access ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Media Access Control ◽  
Delivery Ratio ◽  
Media Access ◽  
Traffic Conditions ◽  
Hoc Networks ◽  
Transmission Overhead

In vehicular ad hoc networks (VANETs), many schemes for a multi-channel media access control (MAC) protocol have been proposed to adapt to dynamically changing vehicle traffic conditions and deliver both safety and non-safety packets. One such scheme is to employ both time-division multiple access (TDMA) and carrier-sense multiple access (CSMA) schemes (called a hybrid TDMA/CSMA scheme) in the control channel (CCH) interval. The scheme can adjust the length of the TDMA period depending on traffic conditions. In this paper, we propose a modified packet transmitted in the TDMA period to reduce transmission overhead under a hybrid TDMA/CSMA multi-channel MAC protocol. Simulation results show that a MAC protocol with a modified packet supports an efficient packet delivery ratio of control packets in the CCH. In addition, we analyze the hybrid TDMA/CSMA multi-channel MAC protocol with the modified packet under saturated throughput conditions on the service channels (SCHs). The analysis results show that the number of neighbors has little effect on the establishment of the number of time slots in TDMA periods and on SCHs under saturated throughput conditions.

scholarly journals Vehicle Density Based Forwarding Protocol for Safety Message Broadcast in VANET

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jiawei Huang ◽  
Yi Huang ◽  
Jianxin Wang
Keyword(s):  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Medium Access ◽  
Safety Message ◽  
Vehicle Density ◽  
Multihop Broadcast ◽  
Hoc Networks ◽  
Time Critical ◽  
Safety Applications

In vehicular ad hoc networks (VANETs), the medium access control (MAC) protocol is of great importance to provide time-critical safety applications. Contemporary multihop broadcast protocols in VANETs usually choose the farthest node in broadcast range as the forwarder to reduce the number of forwarding hops. However, in this paper, we demonstrate that the farthest forwarder may experience large contention delay in case of high vehicle density. We propose an IEEE 802.11-based multihop broadcast protocol VDF to address the issue of emergency message dissemination. To achieve the tradeoff between contention delay and forwarding hops, VDF adaptably chooses the forwarder according to the vehicle density. Simulation results show that, due to its ability to decrease the transmission collisions, the proposed protocol can provide significantly lower broadcast delay.

scholarly journals A Survey of TDMA-based MAC Protocols for Vehicular Ad Hoc Networks

2019 ◽  
Vol 8 (5C) ◽  
pp. 1247-1259
Keyword(s):  
Access Control ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocols ◽  
Media Access Control ◽  
Media Access ◽  
Medium Access Control Protocols ◽  
Medium Access ◽  
Open Problems ◽  
Qualitative Comparison

MAC design in a vehicle network is a challenging task due to high node speed, frequent topology changes, lack of infrastructure, and different QoS requirements. Several medium access control protocols based on Time Division Multiple Access (TDMA) have recently been suggested for VANETs in an effort to guarantee that all cars have sufficient time to send safety messages without collisions and to decrease the end-to-end delay and the loss ratio of packets. The reasons for using the collision-free media access control paradigm in VANETs are identified in this document. We then present a new topology-based classification and provide an overview of the MAC protocols suggested for VANETs based on TDMA. We concentrate on these protocols ' features as well as their advantages and constraints. Finally, we provide a qualitative comparison and address some open problems that need to be addressed in future studies to enhance the efficiency of TDMA-based MAC protocols for vehicle-to-vehicle (V2V) and vehicle to infrastructural (V2I) communications.

scholarly journals Adaptive Beaconing in Mobility Aware Clustering Based MAC Protocol for Safety Message Dissemination in VANET

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Nishu Gupta ◽  
Arun Prakash ◽  
Rajeev Tripathi
Keyword(s):  
Ad Hoc ◽  
Mac Protocol ◽  
Ieee 802.11P ◽  
Bandwidth Utilization ◽  
Transmission Frequency ◽  
Vehicle Communication ◽  
Safety Message ◽  
Vehicle To Vehicle ◽  
Wide Range

Majority of research contributions in wireless access in vehicular environment (WAVE)/IEEE 802.11p standard focus on life critical safety-related applications. These applications require regular status update of vehicle’s position referred to as beaconing. Periodic beaconing in vehicle to vehicle communication leads to severe network congestion in the communication channel. The condition worsens under high vehicular density where it impacts reliability and upper bound latency of safety messages. In this paper, WAVE compliant enhancement to the existing IEEE 802.11p protocol is presented which targets prioritized delivery of safety messages while simultaneously provisioning the dissemination of nonsafety messages. Proposed scheme relies on dynamic generation of beacons to mitigate channel congestion and inefficient bandwidth utilization by reducing transmission frequency of beacons. Through the use of clustering mechanism, different beaconing frequencies and different data transmission rates are assigned to prioritize vehicular mobility. Through extensive simulation results, the performance of the proposed approach is evaluated in terms of a wide range of quality of service (QoS) parameters for two different transmission ranges. Results show that the proposed protocol provides significant enhancement and stability of the clustered topology in vehicular ad hoc network over existing standard and other protocols with similar applications.

scholarly journals Media Access Control Protocol in Ad Hoc Network Based on Hybrid Antennas

2013 ◽  
Vol 765-767 ◽  
pp. 1956-1959
Author(s):  
Ming Ce Cheng ◽  
Ying Li
Keyword(s):  
Access Control ◽  
Data Transmission ◽  
Ad Hoc Network ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Directional Antennas ◽  
Media Access Control ◽  
Media Access ◽  
Simulation Results ◽  
Media Access Control Protocol

In order to solve the problem of the communication asymmetry problems in hybrid ad hoc network because of the introduction of directional antennas, we propose a hybrid MAC protocol termed DFMAC protocol, which achieving data transmission by one hop through the use of exchange RTS by multiple hops. The protocol takes the benefit of directional antennas and can be used by node equipped with Omni-directional antennas, simulation results show that the DFMAC protocol performs well in improving the network throughput.

scholarly journals Transmission Capacity Characterization in VANETs with Enhanced Distributed Channel Access

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 340 ◽  
Author(s):  
Wei Liu ◽  
Xinxin He ◽  
Zhitong Huang ◽  
Yuefeng Ji
Keyword(s):  
Large Scale ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Path Loss ◽  
Transmission Capacity ◽  
Ieee 802.11P ◽  
Small Scale ◽  
Channel Access ◽  
Transmission Scheme

The traditional research on the capacity of the Vehicular Ad Hoc Networks (VANETs) mainly lacks realistic models mimicking the behaviors of vehicles and the MAC protocol applied by IEEE 802.11p. To overcome these drawbacks, in this paper, the network transmission capacity analysis for VANETs is carried out from the perspective of the spatial geometric relationship among different vehicles. Specifically, the transmission scheme in this system is set to mimic enhanced distributed channel access (EDCA) protocol, in which the division of priorities is taken into account both the data type and the transmission distance requirement. Meanwhile, the moving pattern of vehicles is described as the classic car-following model according to realistic characteristics of VANET, and the propagation channel is modeled as a combination of large-scale path-loss and small-scale Rayleigh fading. Based on this model, the transmission opportunity under EDCA protocol is quantified and compared with that of CSMA/CA, and then the outage probability is calculated under the worst interfered scenario. Finally, the transmission capacity is thereby calculated and verified by the simulation results.

scholarly journals An Accurate Performance Analysis of Hybrid Efficient and Reliable MAC Protocol in VANET under Non-saturated Conditions

2017 ◽  
Vol 7 (2) ◽  
pp. 999 ◽  
Author(s):  
Akram A. Almohammedi ◽  
Nor K. Noordin ◽  
A. Sali ◽  
Fazirulhisyam Hashim ◽  
Abdulmalek Al-Hemyari
Keyword(s):  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Mac Protocol ◽  
Packet Delivery Ratio ◽  
Ieee 802.11P ◽  
Accurate Estimation ◽  
Delivery Ratio ◽  
Medium Access ◽  
Packet Delivery ◽  
Safety Applications

Vehicular Ad Hoc Networks (VANETs) is a technology supporting two types of applications, safety and service applications with higher and lower priorities respectively. Thereby, Medium Access Control (MAC) protocol is designed to provide reliable and efficient data broadcasting based on prioritization. Different from the IEEE 1609.4 (legacy), HER-MAC protocol is a new multi-channel MAC proposed for VANETs, offering remarkable performance with regards to safety applications transmission. This paper focuses on the analysis of packet delivery ratio of the HER-MAC protocol under non-saturated conditions. 1-D and 2-D Markov chains have been developed for safety and non-safety applications respectively, to evaluate mathematically the performance of HER-MAC protocol. The presented work has taken into account the freezing of the backoff timer for both applications and the backoff stages along with short retry limit for non-safety applications in order to meet the IEEE 802.11p specifications. It highlights that taking these elements into consideration are important in modeling the system, to provide an accurate estimation of the channel access, and guarantees that no packet is served indefinitely. More precise results of the system packet delivery ratio have been yield. The probability of successful transmission and collisions were derived and used to compute the packet delivery ratio. The simulation results validate the analytical results of our models and indicate that the performance of our models outperformed the existing models in terms of the packet delivery ratio under different number of vehicles and contention window.

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