Rhythm and Randomness in Human Contact

TL;DR

This paper investigates human contact patterns, revealing a combination of circadian rhythms and heavy-tailed waiting time distributions, which impact opportunistic communication strategies.

Contribution

It provides a detailed analysis of human contact data showing the coexistence of rhythmic and random contact patterns, and introduces a simple model to replicate these behaviors.

Findings

Presence of circadian rhythm in contact patterns

Heavy-tailed inter-contact time distributions

Graphical analysis affects visibility of patterns

Abstract

There is substantial interest in the effect of human mobility patterns on opportunistic communications. Inspired by recent work revisiting some of the early evidence for a L\'evy flight foraging strategy in animals, we analyse datasets on human contact from real world traces. By analysing the distribution of inter-contact times on different time scales and using different graphical forms, we find not only the highly skewed distributions of waiting times highlighted in previous studies but also clear circadian rhythm. The relative visibility of these two components depends strongly on which graphical form is adopted and the range of time scales. We use a simple model to reconstruct the observed behaviour and discuss the implications of this for forwarding efficiency.