Content synchronization using device-to-device communication in smart cities

With the acceleration of high data demand from mobile users and urbanization, Device-to-Device (D2D) communication networks have emerged as a new paradigm to alleviate the traffic load on the cellular networks. Due to high mobility of devices, establishing and ensuring the success of D2D transmission in an intermittently connected network is a major challenge. In this paper, we consider the challenging problem of synchronizing the content of a subset of nodes in D2D networks. We adopt the City Section mobility model to mimic node movement in a city area, and produce theoretical analysis to the properties of the model. Based on this model, we propose two content synchronization strategies called direct contact synchronization and relay-assisted synchronization. We provide theoretical analysis to the performance of the two strategies, which derives the theoretical upper bound of their synchronization delay. We further conduct simulations to compare the proposed algorithms, which confirms the theoretical conclusion that relay-assisted synchronization substantially outperforms direct contact synchronization in terms of success rate and delay with a slight increase in the cost.