Node Connectivity in Vehicular Ad Hoc Networks with Structured Mobility

Abstract

Vehicular Ad hoc NETworks (VANETs) is a subclass of Mobile Ad hoc NETworks (MANETs). However, automotive ad hoc networks will behave in fundamentally different ways than the predominated models in MANET research. Driver behaviour, mobility constraints and high speeds create unique characteristics in the network. All of these constraints have implications on the VANET architecture at the physical, link, network, and application layers. To facilitate the cross-layer designs for VANETs, understanding of the relationship between mobility and network connectivity is of paramount importance. In this paper, we focus on studying transport systems with structured mobility (e.g., bus systems), which have unique characteristics on the road such as fixed routes that have never been explored in previous work. The main contributions of this paper are three-fold: 1) we provide an analytical framework including the design requirements of the mobility model for realistic vehicular network studies, and metrics for evaluating node connectivity in vehicular networks; 2) we demonstrate, through simulation, the impacts of marco- and micro-mobility models, and various transport elements on network connectivity; and 3) we show that multi-hop paths perform dramatically poorer than single-hop links in vehicular networks. Specifically, two- hop and three-hop (communication) paths can only respectively achieve less than 27% and 13% of the average duration of single-hop links. Such kind of knowledge of the performance of multi-hop transmission will be significant for the studies of routing algorithm and other networking functions in vehicular networks.