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Title:	Contention-based forwarding algorithms with reliable recovery strategy for vehicular ad hoc networks
Authors:	Mojtaba Asgari (P44072)
Supervisor:	Mahamod Ismail, Prof. Dr.
Keywords:	Vehicular ad hoc networks (Computer networks)
Issue Date:	27-Mar-2018
Description:	Vehicular Ad hoc NETworks (VANETs) provide new wireless applications in the vehicle by offering information, advertisements and entertainment services for drivers and passengers, thus improving public safety. Most VANET applications occur between distant vehicles, roadside equipment, or both, that require multi-hop forwarding. Frequent disconnections or partitioning, and high mobility with variations in network density and vehicle velocities are important challenges that influence the performance of VANETs and affect reliability and efficiency of the existing forwarding algorithms. Recent research studies show that Geographical Contention-Based Forwarding (GCBF) algorithms such as Contention-Based Forwarding (CBF), Beaconless Routing Algorithm for Vehicular Environments (BRAVE), and Intelligent Beaconless (IB), that are beaconless are preferable in highly dynamic vehicular networks. This thesis proposes a mobility-aware contention-based forwarding algorithm with reliable recovery strategy for VANET. Three GCBF algorithms to overcome the frequent disconnections and variations in network density and vehicle velocities have been developed. Firstly, a reliable recovery strategy based on store-carry-forward coupled with CBF (SCF-CBF algorithm) been developed to resolve disconnection problem. In connected network partitions, CBF-SCF operates in a greedy mode, while in disconnected conditions; it switches to SCF mode to forward between partitions. Regarding the neighbor discovery mechanism in SCF mode, two algorithms are designed and implemented: neighbor detection based on beacon request (CBF-SCF-BR) and beaconless neighbor detection (CBF-SCF-BL). Secondly, for high mobility problem, a new weighted contention-timer function based on greediness and link stability parameters is derived and formulated. The parameters affect the quality of the selected next-hop. Then, Mobility-Aware Contention-Based Forwarding (MACBF) algorithm as an improvement to the CBF is developed to utilize the timer. The weighting factors optimally trade-off between greediness, to select the shortest path, and link stability, to reduce communications over lossy links. Thirdly, an integrated MACBF-SCF algorithm using MAC-NET cross-layer approach with disconnection-toleration and mobility-awareness capabilities has been developed. MACBF-SCF is a reliable and efficient forwarding algorithm based on modified IEEE 802.11 MAC frames. In the case of MAC transmission failure, the packet sent to the network layer for SCF operation. Simulation results of CBF-SCF show an increase in packet delivery ratio with an approximate average value of 45.65% and 51.66%, and a decrease in forwarding overhead with the value of 24.82% and 92.35%, compared to CBF and BRAVE, respectively. Moreover, the network performance is further improved using MACBF with optimal selection of the parameters weighting factor. MACBF-SCF algorithm outperforms IB, with about 13.71% higher packet delivery ratio, and lowers average delay and overhead as much as about 77.41% and 71.16%, respectively, for different network traffic loads. Thus it can be reliably and efficiently applied in highly mobile vehicular networks.,Ph.D.
Pages:	121
Call Number:	TE228.37.A834 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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