Supporting Offloading of Dynamic Content Requests with Opportunistic Networks: an Analytic Model

Offloading can be used as a technique to overcome the cellular capacity crunch due to the surge of mobile data traffic demand in overloaded scenarios. Multiple offloading techniques have been investigated, from modifications inside the cellular network architecture, to integration of multiple wireless broadband infrastructures, to exploiting direct communications between mobile devices. In this work we focus on the latter type of offloading, and specifically on offloading through opportunistic networks. As opposed to most of the literature looking at this type of offloading, in this work we consider the case where requests for content are non-synchronised, i.e. users request content at different random points in time. We support this scenario through a very simple offloading scheme, whereby no epidemic dissemination occurs in the opportunistic network. Thus, our scheme is minimally invasive for users' mobile devices, as it uses only minimally their resources. Then, we provide an analysis of the efficiency of our offloading mechanism (in terms of percentage of offloaded traffic) in representative vehicular and pedestrian settings, where content needs to be delivered to subsets of the users in specific geographical areas. We then propose an analytic model of the described algorithms, with detailed specific models for each considered scenario. The model is then validated by simulation. This analytic model can be useful in predicting the performance of the system depending on various key parameters and could be used in real time optimization algorithms to adapt the system to the dynamic traffic conditions.