scholarly journals A QoS Based Adaptive Backoff Scheme for Vehicular Ad Hoc Networks

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4421 ◽  
Author(s):  
Tianjiao Zhang ◽  
Qi Zhu

The media access control (MAC) protocol is a key element in the design of vehicular ad hoc networks (VANETs) that directly affects the network performance. The backoff schemes of existing MAC protocols apply the single backoff process and therefore are not suitable for multi-class data transmission. Additionally, they cannot satisfy the delay requirements of emergency data in the case of varying number of vehicles, causing an adverse effect to the intelligent transportation system (ITS). This paper presents a priority-based adaptive backoff scheme that can enhance the binary exponential backoff (BEB) algorithm as well as the polynomial backoff (QB) algorithm. This system distinguishes priority data with different delay requirements first and designs different backoff schemes for each type of data later. The two-dimensional Markov Chain is used to analyze the backoff scheme and determine the expressions for throughput and delay. The simulation results show that the backoff scheme provided by this paper can reduce the average data delay and regulate each kind of data delay adaptively, according to the varying number of vehicles and different delay requirements.

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3028 ◽  
Author(s):  
VanDung Nguyen ◽  
Tran Anh Khoa ◽  
Thant Zin Oo ◽  
Nguyen H. Tran ◽  
Choong Seon Hong ◽  
...  

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.


2018 ◽  
Vol 17 ◽  
pp. 01004
Author(s):  
Shengwei Wang ◽  
Jun Liu ◽  
Wei Cai ◽  
Minghao Yin ◽  
Lingyun Zhou ◽  
...  

Media access control is an important technology in ad hoc networks. Based on the multi-hop Pseudo Bayesian (PB) algorithm and the single-hop Fast Conflict Resolution algorithm (FCR), in this paper, we propose a Multi-hop Fast Conflict Resolution (MFCR) algorithm for ad hoc networks. We make the detailed introduction of the theoretical model, the pseudo Bayesian analysis and the algorithm deign. MFCR employs a competition probability forecasting method, which is similar to the backoff counter used in FCR, combined with the handshake process used in PB to solve the utilization and the fairness problems of the time slot allocation. Simulations show that the MFCR has evident improvement in the network performance.


2014 ◽  
Vol 24 (8) ◽  
pp. 2214-2225 ◽  
Author(s):  
Ye-Qun WANG ◽  
Feng YANG ◽  
Guo-Ce HUANG ◽  
Heng-Yang ZHANG ◽  
Jian-Xin GUO

2005 ◽  
Vol 12 (3) ◽  
pp. 147-157
Author(s):  
Giuseppe Caizzone ◽  
Paolo Giacomazzi ◽  
Luigi Musumeci ◽  
Gabriella Saddemi ◽  
Giacomo Verticale

2018 ◽  
Vol 7 (3.16) ◽  
pp. 76
Author(s):  
Deepak . ◽  
Rajkumar .

Vehicular ad hoc networks is an emerging area for researchers to provide intelligent transportation system to the society. It is due to the wide area of applications of VANETs interest is developed among the people from different countries to be a part of it. Therefore many projects had been started and also presently working to implement VANETs in real world scenario. The main challenge in its implementation is to provide a secure mechanism against the various attacks and threats that have the capability to bring the network performance significantly down. In this paper to overcome different types of authentication based attacks in VANETs an ECDSA based secure routing protocol SE-AODV is proposed with security features incorporated in already existing AODV routing protocol. The performance of SE-AODV is evaluated and compared with original AODV and AODV with black hole attack (BH-AODV). The SE-AODV shows better performance with the parameters used for comparison with the variation in vehicle density, speed of vehicles and simulation time. 


Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2764 ◽  
Author(s):  
Huanhuan Yang ◽  
Zongpu Jia ◽  
Guojun Xie

As an auxiliary facility, roadside units (RSUs) can well improve the shortcomings incurred by ad hoc networks and promote network performance in a vehicular ad hoc network (VANET). However, deploying a large number of RSUs will lead to high installation and maintenance costs. Therefore, trying to find the best locations is a key issue when deploying RSUs with the set delay and budget. In this paper, we study the delay-bounded and cost-limited RSU deployment (DBCL) problem in urban VANET. We prove it is non-deterministic polynomial-time hard (NP-hard), and a binary differential evolution scheme is proposed to maximize the number of roads covered by deploying RSUs. Opposite-based learning is introduced to initialize the first generation, and a binary differential mutation operator is designed to obtain binary coding. A random variable is added to the traditional crossover operator to increase population diversity. Also, a greedy-based individual reparation and promotion algorithm is adopted to repair infeasible solutions violating given constraints, and to gain optimal feasible solutions with the compromise of given limits. Moreover, after selection, a solution promotion algorithm is executed to promote the best solution found in generation. Simulation is performed on analog trajectories sets, and results show that our proposed algorithm has a higher road coverage ratio and lower packet loss compared with other schemes.


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