A simplified Cluster – Based Gateway Selection Scheme for Multihop Vehicular Networks

ABSTRACT

An integration of Vehicular Ad-hoc Network (VANET) and cellular network, e.g. LTE

is a promising architecture for future machine-to-machine applications. This

integration helps vehicles to have steady internet connection through cellular network

and at same time can communicate with each other. However, dead spot areas and

unsuccessful handover processes, due to vehicles high speed, can disturb the

implementation of this kind of architecture. In this thesis, a Simplified Cluster –

Based Gateway Selection (SCGS) Scheme for Multi-hop Vehicular networks is

proposed. The main aim of this research is to enhance the integration between

VANET and cellular network and to extend coverage in areas where there is no

coverage. An enhanced version of Hybrid Wireless Mesh Protocol (E-HWMP) is

proposed where it is a combination of IEEE802.11p and IEEE802.11s for multi-hop

vehicular networks. E-HWMP provide a tradeoff between reactive and proactive

gateway discovery solutions " consists of adjusting the scope for the gateway

advertisement". The basic idea behind hybrid routing protocol is to use proactive

routing mechanism inside the coverage zone at a certain time while utilizing a

reactive routing mechanism on demand. An integrated simulation environment

combined of VanetMobiSim and NS2 is used to simulate and evaluate the proposed

scheme. An analytical model is also derived which is implemented by Matlab to

optimize the proposed scheme. Simulation results show that, E-HWMP protocol

performed better than Ad-hoc on demand Distance Vector (AODV) routing protocol

and Hybrid Wireless Mesh Protocol (HWMP) routing protocol. Furthermore, SCGS

through E-HWMP is compared with other cluster-based gateway selection algorithms

i.e. CMGM and SGS that used in other related works; the result shows that SCGS

scheme through E-HWMP protocol outperform the other cluster- based gateway

selection schemes in terms of connection delay, control packet overhead, packet

delivery ratio and overall throughput. Finally, results from analytical model are

compared to simulation results to validate the approach of this thesis. Both analytical

and simulation results agreed that: connectivity probability increases as average vehicle density increases and increased average vehicle speed degrades connectivity.