Opportunistic Communication by Pedestrians with Roadside Units as Message Caches

Abstract

Opportunistic communication is one of the critical technologies in the area of advertisement, information sharing, disaster evacuation guidance in delay-tolerant networks (DTNs), vehicular ad hoc networks (VANETs) and so on. The efficiency of opportunistic communication is correlated to the movement pattern. Random walks are often used as the movement patterns of a pedestrian. Even amongst those, Levy walk that is a family of random walks is attracted attention as a human movement pattern. There are lots of works of Levy walk in the context of target detection in swarm robotics, analyzing human walk patterns, and modeling the behavior of animal foraging in recent years. According to these results, it is known as an efficient method to search and come across one another in a two-dimensional plane. However, all these works assume a continuous plane and hardly any results on graphs are available. In this paper, we focus on message delivery based on opportunistic communication by pedestrians who move based on Levy walk and Random walk movement patterns on the road network of a city. Moreover, we introduce roadside units located in the city, which play a role in the distributed message cache. So, we evaluate the impact of roadside units on message delivery in delay-tolerant networks consists of mobile devices of human pedestrians. We assume Random walk and Levy walk as a pedestrian mobility model. Our simulation results show that the roadside units have a significant impact on message delivery with a small number of pedestrians.