Delay Tolerance in Underwater Wireless Communications: A Routing Perspective

Table 1

Summary of underwater DTN routing protocols.

Routing protocol	Communication initiation mechanism	Infrastructure assistance	Routing decision	Location information dependence	Number of copies	Performance indicator
PASR	Sender	No	Distributed	No	Single	Replication control
DDD	Receiver	No	Centralized	No	Single	Energy efficiency
UDTN	Receiver	No	Distributed	No	Single	End-to-end delay minimization
Sweeper	Receiver	Yes	Centralized	Yes	Single	UW nodes localization
Tier-based UDTN	Sender	Yes	Centralized	Yes	Single	Energy, delay, and packet drop constraints
QDTR	Sender	No	Distributed	No	Multiple	Energy efficiency and end-to-end delay
RBAR	Sender	Yes	Centralized	No	Multiple	Energy efficiency
PBDTP	Sender	Yes	Not Available	No	Multiple	Long delay tolerance