  Underwater optical wireless links have limited range and intermittent
connectivity due to the hostile aquatic channel impairments and misalignment
between the optical transceivers. Therefore, multi-hop communication can expand
the communication range, enhance network connectivity, and provide a more
precise network localization scheme. In this regard, this paper investigates
the connectivity of underwater optical wireless sensor networks (UOWSNs) and
its impacts on the network localization performance. Firstly, we model UOWSNs
as randomly scaled sector graphs where the connection between sensors is
established by point-to-point directed links. Thereafter, the probability of
network connectivity is analytically derived as a function of network density,
communication range, and optical transmitters' divergence angle. Secondly, the
network localization problem is formulated as an unconstrained optimization
problem and solved using the conjugate gradient technique. Numerical results
show that different network parameters such as the number of nodes, divergence
angle, and transmission range significantly influence the probability of a
connected network. Furthermore, the performance of the proposed localization
technique is compared to well-known network localization schemes and the
results show that the localization accuracy of the proposed technique
outperforms the literature in terms of network connectivity, ranging error, and
number of anchors.
