Do we really need cloud? Estimating the fog computing capacities in the city of Barcelona

Fog computing has emerged as a novel and challenging technology intended to complement the features of the cloud computing paradigm by exploiting the opportunities of locality. Moving some computation to the edge of the network is especially attractive in a smart city scenario, where a vast network of heterogeneous resources is widely distributed all over the city. In such scenario, using the available fog resources allows the deployment of a rich family of new services that combine the advantages of both, cloud and fog technologies. In fact, the amount of computing load that can be moved down to the edge will actually depend on the edge devices capacity. But, in this context, some key questions arise; for example, how much computing capacity is there at the edge? Are there enough resources to execute efficiently some deep computing applications? And the most relevant, could the cloud layer be ignored in case of sufficient fog resources? In this paper, we analyze and estimate the fog computing capacity in a major European smart city: Barcelona. To this end, we analyze the available information about Barcelona and estimate the number of computing devices in the city that could be part of a fog environment, including personal computers, smartphones, on-board car computers, WiFi routers, and some other embedded computers deployed as part of city services. Then, we estimate an average computing capacity for each type of computing device, and obtain the potential computing peak performance for an eventual fog cluster of Barcelona. We believe the results of this work will be useful to provide insights into the aforementioned open questions, but also for fog technology researchers and developers to understand the order of magnitude of a real fog computing scenario.