Opportunistic Network Mobility Model And Routing Algorithm Based On The Commercial Area

As a branch of ad-hoc networks, opportunistic network relies on the encountering opportunity of nodes to relay and transmit messages, so mobility model is an important basis for the measurement of the performance of opportunistic networks.As a common scenario in daily life, commercial area possesses enormous value for the research of opportunistic networks. However, current research pays little attention on mobility models in such area, except for the collection of mobility trace in specific commercial area. Based on the discrepancy between internal and external commercial areas in terms of population density, walking speed, encounter probability and message relaying, we propose an opportunistic network mobility model based on commercial area(MMCA). In this model, commercial area is divided into two parts: internal and external areas. We analyzed the reasons for different speed of messages spreading by combining MMCA with Manhattan model and conducted performance analysis for MMCA using a modified SIR model and ONE(Opportunistic Networks Environment) simulation platform. The experimental findings show that change in in-and-out probability will affect spreading rate of messages within the network and increase in in-and-out probability will accelerate spreading rate of messages in MMCA. Meanwhile, we have verified the correctness of the MMCA by comparing predictions of the modified SIR model and simulative data in terms of number of nodes, walking speed, communication range and the size of areas.This paper puts forward a routing algorithm(RACA) based on the MMCA. In this algorithm, nodes transfer messages according to their location. In internal area nodes transfer messages using a limited copy algorithm, while in external area nodes transfer messages using unlimited copy algorithm. Compared with the Epidemic and Spray and Wait routing protocols, the RACA has a higher deliverability and a lower transmission delay, and its overhead is not very large, only a bit higher than that of the Spray and Wait. These experimental results prove that the RACA has a better network performance than the Epidemic and the Spray and Wait in commercial area scenarios.