Wireless ad hoc and sensor networks are envisioned to be self-organizing and
autonomous networks, that may be randomly deployed where no fixed infrastructure
is either feasible or cost-effective. The successful commercialization of such networks
depends on the feasible implementation of network services to support security-aware
applications.
Recently, free space optical (FSO) communication has emerged as a viable technology
for broadband distributed wireless optical sensor network (WOSN) applications.
The challenge of employing FSO include its susceptibility to adverse weather
conditions and the line of sight requirement between two communicating nodes. In
addition, it is necessary to consider security at the initial design phase of any network
and routing protocol. This dissertation addresses the feasibility of randomly deployed
WOSNs employing broad beam FSO with regard to the network layer, in which two
important problems are specifically investigated.
First, we address the parameter assignment problem which considers the relationship
amongst the physical layer parameters of node density, transmission radius
and beam divergence of the FSO signal in order to yield probabilistic guarantees on
network connectivity. We analyze the node isolation property of WOSNs, and its
relation to the connectivity of the network. Theoretical analysis and experimental
investigation were conducted to assess the effects of hierarchical clustering as well as fading due to atmospheric turbulence on connectivity, thereby demonstrating the
design choices necessary to make the random deployment of the WOSN feasible.
Second, we propose a novel light-weight circuit-based, secure and integrated routing
and localization paradigm within the WOSN, that leverages the resources of the
base station. Our scheme exploits the hierarchical cluster-based organization of the
network, and the directionality of links to deliver enhanced security performance including
per hop and broadcast authentication, confidentiality, integrity and freshness
of routing signals. We perform security and attack analysis and synthesis to characterize
the protocol’s performance, compared to existing schemes, and demonstrate its
superior performance for WOSNs.
Through the investigation of this dissertation, we demonstrate the fundamental
tradeoff between security and connectivity in WOSNs, and illustrate how the transmission
radius may be used as a high sensitivity tuning parameter to balance there
two metrics of network performance. We also present WOSNs as a field of study that
opens up several directions for novel research, and encompasses problems such as
connectivity analysis, secure routing and localization, intrusion detection, topology
control, secure data aggregation and novel attack scenarios
