Ad hoc networks
are infrastructure-less and self-organizing networks that consist of static or
mobile nodes with limited bandwidth, computing ability and energy. These
networks are deployed for a wide range of civilian and military applications.
Having an efficient and reliable routing protocol for communication
between the nodes can be critical. Our goal in this thesis is to exploit
Multi-Beam directional Antennas (MBAs) to significantly reduce the
end-to-end (E2E) delay in multi-hop ad hoc networks that service multiple traffic
flows. We conduct this work in four major steps. First, we explore the
benefits of directional antennas, from the standpoint of single-beam
ones, for traditional routing protocols. We propose a single-beam directional
antenna MAC protocol in the process. Secondly, using Flying Ad hoc Networks
(FANETs) as an example, we make the case that MBAs are yet to be exploited for
E2E delay reduction. To that end, we propose a multi-beam directional antenna
MAC protocol. Third, as a consequence of the case made in the second step, we
propose a Mixed Integer Linear Programming (MILP) model that exploits
MBAs’ capabilities for delay minimization. Solving this model shows that
the routes that are selected for the different flows need to have
certain key characteristics that depart from the widespread traditional
shortest-route philosophy. Based on these characteristics, we design, in the
fourth step, an MBA-Delay-Reducing Routing protocol (MBA-DRR) that fully
exploits the benefits of MBAs for delay reduction. The benefits of
this protocol apply to all types of multi-hop MBA-based ad hoc networks, both
mobile and static. As a matter of fact, the evaluation on a multi-flow
static scenario shows that MBA-DRR, with a delay of just 4.4 ms, gets very close to the optimal solution that has a
delay of 2.5 ms. Comparatively, Reactive-Geographic
hybrid Routing (RGR), a shortest-route-based protocol, has a delay of 48 ms. An evaluation on a representative multi-flow
mobile scenario shows that, while single-beam directional MAC reduces the E2E
latency from 700 ms to 40 ms,
and multi-beam directional MAC halves this to 20 ms,
our proposed routing protocol further cuts it to 9 ms.