Vehicular Delay-Tolerant Networks (VDTNs) are a new approach for vehicular
communications where vehicles cooperate with each other, acting as the
communication infrastructure, to provide low-cost asynchronous opportunistic
communications. These communication technologies assume variable delays
and bandwidth constraints characterized by a non-transmission control protocol/
internet protocol architecture but interacting with it at the edge of the
network.
VDTNs are based on the principle of asynchronous communications, bundleoriented
communication from the DTN architecture, employing a store-carryand-
forward routing paradigm. In this sense, VDTNs should use the tight network
resources optimizing each opportunistic contact among nodes.
At the ingress edge nodes, incoming IP Packets (datagrams) are assembled
into large data packets, called bundles. The bundle aggregation process plays
an important role on the performance of VDTN applications. Then, this paper
presents three aggregation algorithms based on time, bundle size, and a hybrid
solution with combination of both. Furthermore, the following four aggregation
schemes with quality of service (QoS) support are proposed: 1) single-class bundle
with N = M, 2) composite-class bundle with N = M, 3) single-class bundle
with N > M, and 4) composite-class bundle with N > M, where N is the number
of classes of incoming packets and M is the number of priorities supported
by the VDTN core network. The proposed mechanisms were evaluated through
a laboratory testbed, called VDTN@Lab. The adaptive hybrid approach and the
composite-class schemes present the best performance for different types of
traffic load and best priorities distribution, respectively