DEMOS Mobility Model

Uruguay has a countrywide implementation of the One Laptop per Child (OLPC) initiative, locally named Plan Ceibal. Children participant in this project carry their laptops from home to school and back every day, enabling the creation of new applications to take advantage of computers ubiquity, mobility and wireless capabilities. In this context, we are deploying the project Domestic Environment Monitoring with Opportunistic Sensor networks (DEMOS), seeking to use Plan Ceibal laptops as an opportunistic network to obtain, transport, aggregate and communicate environmental information from sensors disseminated in locations close to children neighborhoods. The planning of DEMOS deployment involve several scenarios of variable size and characteristics; the evolution of the prototype over the real networks would impose frequent countrywide software updates to thousands of children's laptops, among other logistic limitations. Therefore, in order to overcome such difficulties, speed up the project deployment and minimize costs, we are developing a simulation environment which must preserve the real laptops mobility and other essential characteristics in order to deliver accurate results. Gathering mobility traces from Plan Ceibal laptops would involve the installation of extra hardware such as Global Position System (GPS) devices; even if we were able to get sample traces, they would be tight to a particular scenario, limiting the possibility of changing relevant parameters such as number of laptops, size of mobility areas, speed, among others. Since the existing mobility models do not match our deployment characteristics, we are evolving our own DEMOS Mobility Model (DMM). This paper presents the relevant characteristics of DMM and a prototype scenario generator tool for standard network simulators. We are starting to evaluate an opportunistic routing protocol prototype using DMM.