An Empirical Evaluation of the Student-Net Delay Tolerant Networks

Jing Su, Ashvin Goel, Eyal de Lara

3rd International Conference on Mobile and Ubiquitous Systems: Networks and Services (MOBIQUITOUS), San Jose, CA, July 2006



Radio equipped mobile devices have enjoyed tremendous growth in the past few years. We observe that in the near future it might be possible to build a network that routes delay-tolerant packets by harnessing user mobility and the pervasive availability of wireless devices. Such a delay-tolerant network could be used to supplement wireless infrastructure or provide service where none is available. Since mobile devices in a delay-tolerant network forward packets to nearby users, the devices can use short-range radio, which potentially reduces device power consumption and radio contention. The design of a user mobility based delay-tolerant network raises two key challenges: determining the connectivity of such a network, and determining the latency characteristics and replication requirements of routing algorithms in such a network. To determine realistic contact patterns, we collected user mobility data by conducting two user studies. We outfitted groups of students with instrumented wireless-enabled PDAs that logged pairwise contacts between study participants over a period of several weeks. Experiments conducted on these traces show that it is possible to form a delay-tolerant network based on human mobility. The network has good connectivity, so that routes exist between almost all study participants via some multi-hop path. Moreover, it is possible to effectively route packets with modest replication.