In the underwater sensor networks for underwater environment monitoring application

a network with sufficiently high coverage and connectivity rate is the guarantee of accomplishing the monitoring task.The NCPR algorithm

which is a underwater coverage preserving routing algorithm and oriented to improve the coverage performance

can effectively prolong the coverage time of the networks compared to the LEACH-Coverage-U algorithm.However

the connectivity performance of NCPR is defective

and in the algorithm there exist such a problem that the cluster heads close to the SINK node may die faster than other nodes because of the frequently forwarding of data.In this paper

we propose a distributed network unevenly layered coverage preserving routing algorithm (NULCPR) to improve the performance of NCPR.The network is established from SINK layer by layer

and the communication range of nodes increase with the layer departures form SINK.Each layer executes the NCPR algorithm independently to cluster the nodes in this layer

and the cluster node is used to establish a connective link to maintain the connectivity of the networks.The simulation results show that comparing with NCPR

NULCPR improves the connectivity and coverage rate of the networks

and makes the energy efficiency better.