2016 IEEE International Conference on Acoustic, Speech and Signal Processing(ICASSP)
RSS-BASED SENSOR LOCALIZATION IN UNDERWATER ACOUSTIC SENSOR NETWORKS
Tao Xu
1,2
, Yongchang Hu
3
, Bingbing Zhang
4
and Geert Leus
3
1
Tianjin 712 Communication & Broadcasting Co. Ltd, Tianjin, 300462, China
2
Institute of Microelectronics, Tsinghua University, 100084, Beijing, China
3
Fac. EEMCS, Delft University of Technology, Mekelweg 4, 2628CD, Delft, Netherlands
4
Fac. EE, National University of Defence Technology, 410073, Changsha, China
ABSTRACT
Since the global positioning system (GPS) is not applicable under-
water, source localization using wireless sensor networks (WSNs) is
gaining popularity in oceanographic applications. Unlike terrestrial
WSNs (TWSNs) which uses electromagnetic signaling, underwater
WSNs (UWSNs) require underwater acoustic (UWA) signaling.
Received signal strength (RSS)-based source localization is consid-
ered in this paper due to its practical simplicity and the constraint
of low-cost sensor devices, but this area received little attention
so far because of the complicated UWA transmission loss (TL)
phenomena. In this paper, we address this issue and propose two
novel semidefinite programming (SDP) approaches which can be
solved more efficiently. The numerical results validate our proposed
SDP solvers in underwater environments, and indicate that the
placement of the anchor nodes influences the RSS-based localization
accuracy similarly as in the terrestrial counterpart. We also highlight
that adopting traditional terrestrial RSS-based localization methods
will fail in underwater scenarios.
Index Terms— Underwater, Localization, RSS-based, SDP.
1. INTRODUCTION
Underwater acoustic (UWA) communication systems differ from
terrestrial telemetry due to differences in system geometry and
environmental conditions [1]. Underwater wireless sensor networks
(UWSNs) are envisioned for oceanographic applications such as
pollution monitoring, offshore exploration, disaster prevention, as-
sisted navigation, and tactical surveillance applications, while source
localization is another important task. Apart from localization
protocol designs [2], researchers paid a lot of attention to four
different underwater distance measurement techniques [3] as applied
in TWSNs, including time difference of arrival (TDoA), time of
arrival (ToA), received signal strength (RSS), and angle of arrival
(AoA). ToA is widely employed in underwater source localization
works for measuring the distance, e.g., [4], although it demands
a precise synchronization among nodes which is challenging in
UWSNs. TDoA either uses two different transmission media (like
radio and acoustic waves) or adopts reference beacons to estimate
This work is supported in part by National Natural Science Foun-
dation of China (#61302140), China Postdoctoral Science Foundation
(#2015M570230) and Tianjin Enterprise-Postdoctoral Fund for Selected In-
novation Program, performed under University-Enterprise joint postdoctoral
station between Tsinghua University and Tianjin Zhonghuan Electronic &
Information (Group) Co., Ltd. and also in part at National University
of Defence Technology. We thank Mr. MA Yan from Tianjin 712
Communication & Broadcasting Co. Ltd, Prof. LIU Zewen from Tsinghua
University and Prof. WEI Jibo from National University of Defence
Technology for valuable discussions.
Fig. 1. Demonstration of UWA localization
the distance. However, the former is infeasible since RF is not
applicable in aquatic environments [5], while the latter can lead
to problems due to the unpredictable UWA velocities [6]. AoA
relies on a direct line-of-sight (LOS) UWA transmission path which
may not exist at all unlike in terrestrial radio [7], while typical
multi-path components in UWA channels can also lead to large
errors in AoA measurements [8]. RSS-based underwater source
localization gets less attention as another alternative to measure
distance, since it is difficult to achieve accurate ranging due to
multipath propagations and the complicated UWA transmission loss
(TL) phenomena [3]. However, it can be argued that for certain
water depths, the UWA channels show nice transmission features
that fit well to a TL model and thus RSS-based localization can be
considered for such cases [9]. To represent the TL features of an
UWA channel, the Urick propagation model [10] is among the most
popular, based on which some statistical models are derived [11].
Other UWA TL modeling methods can also be found, e.g., using
Lambert W function [12]. In this paper, we consider RSS-based
UWA localization using UWSNs, where the target is a source node
that transmits acoustic signals to all the anchor nodes (beacons)
which usually lie on the water surface and are able to obtain their
precise locations via GPS as depicted in Fig. 1. Literature studying
RSS-based localization underwater using acoustic waves is rather
rare, yet it includes [9] choosing the Lambert W function to model
the UWA TL and performing a simple triangulation method based
on known distances, [13] combining TOA and RSS measurements
where the RSS-based measurements are simply assumed known
and [14] adopting a terrestrial acoustic wave propagation model to
study RSS-based underwater localization. In this sense, we may for
the first time introduce SDP solvers for UWA RSS-based localization
in UWSNs based on a UWA propagation model.
Notation: Upper (lower) bold-face letters stand for matrices
(vectors); superscript T denotes transpose, [A]
k,m
stands for the
(k, m)th entry of the matrix A, Trace[A] for the trace of the matrix
A, Rank[A] for the rank of the matrix A; R
M
represents the M -
dimensional field of real numbers.
1