Coverage Optimization Algorithms Based on Voronoi
Diagram in Software-Defined Sensor Networks
Min Tang
1
, Feng Yan
1
, Shuguang Deng
2*
, Lianfeng Shen
1
, Sufeng Kuang
1
, Song Xing
3
(1. National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China;
2. College of Communications and Electronics Engineering, Hunan City University, Yiyang 413000, China;
3. Dept. of Information Systems, California State University, Los Angeles, CA 90032, USA)
E-mail: {mtang2014, feng.yan, lfshen, sfkuang}@seu.edu.cn, shuguangdeng@163.com, sxing@calstatela.edu
Abstract—In this paper, two coverage optimization
algorithms based on Voronoi diagram are proposed to reduce the
energy consumption of software-defined sensor networks
(SDSNs). In the first algorithm named Minimax Radius
Algorithm (MRA), we try to reduce the sensing radii of nodes as
much as possible while preserving the original network coverage.
In the second algorithm named Sleeping-based Algorithm (SLA),
we try to set as many nodes as possible into sleep mode without
generating new coverage holes. Simulation results show that both
algorithms can reduce the energy consumption significantly and
the energy reduction rate increases with nodes’ sensing
radius and the number of nodes.
Keywords-software-defined sensor networks; Voronoi diagram;
coverage optimization
I. INTRODUCTION
The rapid development of wireless communications and
electronic technology has greatly promoted the research works
of wireless sensor networks (WSNs) [1]. For many
applications in WSNs, the target area is usually over-covered
in order to achieve real-time monitoring and reliable
information transmission. It is thus very important to optimize
the coverage of the monitoring area in order to reduce the
energy consumption of the entire network.
Software-Defined Network (SDN) [2] is a new network
architecture, in which the control plane and data plane are
separated to ensure the dynamic structure, low cost, high
adaptability, and a programmable network. It is naturally to
introduce the SDN architecture into the application-specific
WANs, which results in the software-defined sensor networks
(SDSNs) [3].
A SDSN consists of the central controllers and software-
defined sensor nodes. The network can be reconfigured by
reprogramming the nodes even after the network deployment
is complete. This renders the SDSN as the primary structure in
our problem solving of the coverage optimization in WSNs
due to its network reconfiguration ability.
There are some related works for the coverage
optimization problem in WSNs in recent years. In [4], for
example, the target area is fully covered in the sense that the
sensing perimeters of all sensor nodes are covered by other
nodes. However, the number of coverage holes, the hole
repairing methods, and the coverage optimization are not
considered in [4]. Similar to [4], the authors in [5-6] propose
to detect the coverage holes by checking whether the sensing
perimeter of each node is covered by its neighbors, then they
use the sensing radius to estimate the diameter of the coverage
holes roughly. The authors in [7-8] propose a coverage
optimization method based on Delaunay triangulation, in
which the coverage holes are repaired by moving nodes [7] or
by adding a number of new nodes [8]. But the network
redundancy might be generated by these two methods. [9]
proposes a k-coverage algorithm to achieve the minimum
connected area and keep the minimum number of sensor nodes
under the k-coverage and 1-connectivity conditions. However,
the robustness of the network is not good enough to consider
the change of network topologies. A dynamic k-coverage
scheduling (DkCS) algorithm is proposed in [10] to extend the
lifetime of the network while keeping the network k-coverage
and energy-efficiency by minimizing the average number of
working sensors. The algorithm solves the k-coverage
problems in moving and stationary scenarios. However, DkCS
generates the extra costs on node communication and
movement. The homology theory is used in coverage holes
detection, and the number of holes is detected by the use of
Rips complex [11]. However, removing the redundancy of the
target area is not taken into consideration in [11]. In [12], the
authors propose the KGS and DKEA algorithms to reduce the
coverage redundancy and the network cost with the progress
of building groups which starts from one node to the whole
target area. When the target area is getting bigger, however,
the time of grouping becomes larger and there are also some
failures in this grouping progress.
It is worth noting that, in recent years Voronoi diagram is
applied into the network coverage in WSNs. For example, two
localized algorithms are proposed in [13-14] based on Voronoi
diagram for coverage boundary detection, which only need the
minimal position information of the neighbors and result in a
lower computational complexity. However, the healing of
coverage holes and removing the added network redundancy
have not been considered. A localized method to build 1-order
Voronoi diagram is proposed in [15]. Based on Voronoi
diagram, the authors in [16-18] use the movement of sensor
nodes to repair the coverage holes. However, more energy will
be consumed during the nodes movement and the coverage
optimization is not taken into consideration for the full
coverage of the target area.
in part by the National Natural Science Foundation of
and the Research Fund of National Mobile
Communications Research Laboratory, Southeast University (No. 2016B02).