  Intermittently Connected Delay-Tolerant Wireless Sensor Networks (ICDT-WSNs),
a branch of Wireless Sensor Networks (WSNs), have features of WSNs and the
intermittent connectivity of Delay-Tolerant Networks (DTNs). The applications
of ICDT-WSNs are increasing in recent years, however, the communication
protocols suitable for this category of networks often fall short. Most of the
existing communication protocols are designed for either WSNs or DTNs and tend
to be inadequate for direct use in ICDT-WSNs. This survey summarizes
characteristics of ICDT-WSNs and their communication protocol requirements, and
examines the communication protocols designed for WSNs and DTNs in recent years
from the perspective of ICDT-WSNs. Opportunities for future research in
ICDT-WSNs are also outlined.
