  Real-time monitoring of traffic density, road congestion, public
transportation, and parking availability are key to realizing the vision of a
smarter city and, with the advent of vehicular networking technologies such as
IEEE 802.11p and WAVE, this information can now be gathered directly from the
vehicles in an urban area. To act as a backbone to the network of moving
vehicles, collecting, aggregating, and disseminating their information, the use
of parked cars has been proposed as an alternative to costly deployments of
fixed Roadside Units.
  In this paper, we introduce novel mechanisms for parking vehicles to
self-organize and form efficient vehicular support networks that provide
widespread coverage to a city. These mechanisms are innovative in their ability
to keep the network of parked cars under continuous optimization, in their
multi-criteria decision process that can be focused on key network performance
metrics, and in their ability to manage the battery usage of each car, rotating
roadside unit roles between vehicles as required. We also present the first
comprehensive study of the performance of such an approach, via realistic
modeling of mobility, parking, and communication, thorough simulations, and an
experimental verification of concepts that are key to self-organization. Our
analysis brings strong evidence that parked cars can serve as an alternative to
fixed roadside units, and organize to form networks that can support smarter
transportation and mobility.
