A Modified Balls-into-Bins Model for Expected Buffer Occupancy in Mobile Opportunistic Networks

Abstract

Due to the unavailability of an end-to-end path between the source and the destination, nodes in Mobile Opportunistic Networks (MON) follow a replication based strategy for message delivery. Such replications occur in bulks during intermittent and very short contact events, which often lead to buffer congestion in the relay nodes, thereby affecting the network performance. Older messages (those which have already been delivered to the destination) also tend to stay in the network for a longer time period hindering the spread of newly generated messages. Earlier works have considered buffer management techniques through local information exchange, which leads to overhead. In this work, an expression for the expected buffer occupancy under a given network scenario is obtained using the notion of a classical balls-into-bins problem. Thereafter, an estimator to estimate the buffer occupancy is designed, which can be directly used in buffer management algorithms without local information exchange. We compare the theoretical model, with estimated and simulated results, to prove the correctness of the model.