The age of impatience

Abstract

Multimedia content dissemination in mobile settings requires significant bandwidth. Centralized infrastructure is often either inadequate or overly expensive to fill the demand. Here, we study an alternative P2P content dissemination scheme for mobile devices (e.g., smart-phones), which leverages local dedicated caches on these devices to opportunistically fulfill user requests. In our model, the allocation of content in the global distributed cache comprising the union of all local caches, determines the pattern of demand fulfillment. By selectively replicating local content at node meetings, the global cache can be driven towards a more efficient allocation. However, the allocation's efficiency itself is determined by a previously overlooked factor - the impatience of content requesters. By describing user impatience in the form of any monotonically decreasing delay-utility functions, we show that an optimal allocation can be efficient computed or approximated. As users become increasingly impatient, the optimal allocation varies steadily between uniform and highly-skewed towards popular content.