Article
A Reliable Handoff Mechanism for Mobile Industrial
Wireless Sensor Networks
Jian Ma
1
, Dong Yang
1,
*
ID
, Hongke Zhang
1
and Mikael Gidlund
2
ID
1
School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China;
14111026@bjtu.edu.cn (J.M.); hkzhang@bjtu.edu.cn (H.Z.)
2
Department of Information Systems and Technology (IST), Mid Sweden University, Sundsvall 85170,
Sweden; mikael.gidlund@miun.se
* Correspondence: dyang@bjtu.edu.cn
Received: 27 June 2017; Accepted: 28 July 2017; Published: 4 August 2017
Abstract:
With the prevalence of low-power wireless devices in industrial applications,
concerns about timeliness and reliability are bound to continue despite the best efforts of researchers to
design Industrial Wireless Sensor Networks (IWSNs) to improve the performance of monitoring and
control systems. As mobile devices have a major role to play in industrial production, IWSNs should
support mobility. However, research on mobile IWSNs and practical tests have been limited
due to the complicated resource scheduling and rescheduling compared with traditional wireless
sensor networks. This paper proposes an effective mechanism to guarantee the performance
of handoff, including a mobility-aware scheme, temporary connection and quick registration.
The main contribution of this paper is that the proposed mechanism is implemented not only
in our testbed but in a real industrial environment. The results indicate that our mechanism
not only improves the accuracy of handoff triggering, but also solves the problem of ping-pong
effect during handoff. Compared with the WirelessHART standard and the RSSI-based approach,
our mechanism facilitates real-time communication while being more reliable, which can help
end-to-end packet delivery remain an average of 98.5% in the scenario of mobile IWSNs.
Keywords:
Industrial Wireless Sensor Networks (IWSNs); handoff triggering; reliable
communication; mobility aware
1. Introduction
Nowadays, growing demands to improve process efficiencies, comply with
environmental regulations, and meet corporate financial objectives faced by a number of companies,
which makes the industry marketplace competitive [
1
]. With a growing number of intelligent devices,
mobile devices have a major role to play in industrial production. The roadmap of Factories
of the Future indicates that mobility support is one of the main requirements in the wireless
scenario [
2
]. Meanwhile, it is necessary to integrate such characteristics into the key technology
of Industry 4.0 [
3
]. As an emerging class of wireless sensor networks (WSNs), IWSNs are
indispensable in industrial production which aim to increase productivity and profit, decrease cost
and provide convenience. However, the issued IWSNs standards, e.g., WirelessHART [
4
] and
ISA100.11a [
5
], introduce mechanisms such as time division multiple access (TDMA) to focus on
monitoring for fixed devices. Research on mobility support in IWSNs has been limited because of the
specific constraints linked to the specific requirements of the industry. Since the applicability of IWSN
protocols is significantly limited to monitoring and control systems by the lack of mobility support [
6
],
this paper presents a new mechanism to deploy a reliable IWSN for applications involved in the
mobility of devices, workers or robots.
Sensors 2017, 17, 1797; doi:10.3390/s17081797 www.mdpi.com/journal/sensors
