Urban gravity: a model for inter-city telecommunication flows

Abstract. We analyze the anonymous communication patterns of 2.5 million customers of a Belgian mobile phone operator. Grouping customers by billing address, we build a social network of cities, that consists of communications between 571 cities in Belgium. We show that inter-city communication intensity is characterized by a gravity model: the communication intensity between two cities is proportional to the product of their sizes divided by the square of their distance. PACS numbers: 89.75.Da, 89.75.Fb, 89.65.EfUrban Gravity: a Model for Intercity Telecommunication Flows 2 Recent research has shown that certain characteristics of cities grow in different ways in relation to population size. While some characteristics are directly proportional to a city’s population size, instead, other features- such as productivity or energy consumption- are not linear but exhibit superlinear or sublinear dependence to population size 1. Interestingly, some of these features have strong similarities with those found in biological cells- an observation that has led to the creation of a metaphor where cities are seen as living entities 2. Interactions between cities, such as passenger transport flows and phone messages, have also been related to population and distance