Performance modeling of routing in delay-tolerant networks with node heterogeneity.

Delay Tolerant Networks (DTNs) are the wireless mobile networks that are attributed by intermittent connectivity among the nodes. Intermittency in such networks is dealt by push-based, replication-based routing protocols such as Two-Hop Routing (2HR) and Epidemic Routing (ER) protocols, that are considered to be primitive and are also widely used, especially if the underlying environment's mobility is unknown. The performance modeling of such routing protocols are considered to be vital among the research community. The current state-of-the-art research in DTN for performance modeling assumes the nodes to have same transmission range. Several factors such as (i) the existence of different radio hardwares from various vendors that come with different coverage ranges and (ii) the power saving mechanisms that especially control the coverage range, would make this identical transmission radii assumption unrealistic. In this paper, we consider the heterogeneous setting of nodes having different transmission radii and provide the performance modeling for the 2HR and ER protocols based on Continuous Time Markov Chain (CTMC). The analytical results are validated by extensive simulations. Our results show that the delivery cost is independent of the transmission range of the nodes and depends only on the total number of nodes in the network. This implies that the energy consumption in an N-node heterogeneous DTN for 2HR and ER protocols, depends only on the energy consumed in a per-message transmission.