Mobile Content Offloading in Database-Assisted White Space Networks

Mobile data offloading leverages more affordable or even free network capacity to reduce the traffic experienced by cellular operators through their limited over-the-air resources. One way to harvest free capacity is to employ the white space, namely, frequencies that are assigned to licensed users but are not actively utilized, as long as no harmful interference is generated. In this article, we characterize the benefits of harnessing node contacts for mobile content offloading through dynamic spectrum access assisted by a white space database (WSDB). We take a content-centric approach and model the selection of distributors among the subscribers of each content served through a base station. We formulate an optimization problem to maximize the offloading gain based on realistic settings. We show that such a problem is NP-hard and devise efficient heuristics for practical mobile data offloading. Our results show that the offloading gain allowed by white space is significant even when WSDB data are inaccurate.