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Feature Articles: Network Technology for Digital Society of the Future—Research and Development of Competitive Network Infrastructure Technologies

Wildlife Detection System Using Wireless LAN Signals

Tomoki Murakami, Shinya Otsuki, Takafumi Hayashi,
Yasushi Takatori, and Kazuo Kitamura


The NTT Group considers the primary industry of agriculture an important field and is promoting development of innovative technologies that integrate agriculture with information and communication technology. This article introduces initiatives related to a wildlife detection system that are part of this work. The system can accurately detect wildlife that enters agricultural land over a wide area, using only fluctuations in wireless local area network radio signals.

Keywords: wireless LAN, sensing, machine learning


1. Introduction

Damage to agricultural produce by wildlife totals around 20 billion yen per year in Japan, with damage from wild boar and deer accounting for approximately 80% of this (Fig. 1). This damage also contributes to secondary damage such as a declining desire to continue farming, and unutilized arable land, resulting in deeper social issues than are represented by these numbers. Many institutions are actively studying measures to counter such wildlife damage using information and communication technology to detect intrusions, prevent intrusions, capture, or chase away the wildlife. The NTT laboratories are focusing on sensing technologies for detecting intrusions using radio waves.

Fig. 1. Trends in value of agricultural damage due to wildlife.

2. Trends in sensing technologies using radio waves

Radio waves are used as a communication medium by mobile terminals such as smartphones and are widely used in mobile communications and wireless local area network (LAN) systems. They are also used for non-communications applications such as sensing, microwave ovens, GPS (Global Positioning System), and wireless power transmission, making them essential for everyday life. Sensing technologies have attracted particular attention recently, and application domains have been expanding, from detecting people and animals (a domain already in use) to object and behavior recognition (a new domain).

Sensing technologies utilizing radio waves can be categorized by whether the object being detected has a radio device or not. We refer to the latter as device-free sensing. Generally, device-free sensing is done using various types of radio waves such as microwaves, millimeter waves, infrared rays, and visible light. In this study we focus on microwaves, which are very good compared to other radio waves in terms of detection range, detection of obstructed objects, and detection at night (Table 1). Moreover, if wireless LAN microwave frequencies are used, some existing wireless LAN devices can be reused, reducing the cost of deploying the system.

Table 1. Device-free sensing characteristics.

3. Wildlife detection system using wireless LAN radio waves

For the proposed system, an IEEE (Institute of Electrical and Electronics Engineers) 802.11ac [1] wireless LAN access point and several terminals are deployed in the sensing area, and fluctuations in the radio waves between them are analyzed to detect wildlife in the area (Fig. 2). Specifically, a separate collection device deployed in the area collects the radio packets for Channel State Information (CSI)* notifications, which are periodically exchanged between the access point and terminals and are necessary for transmission beam forming. The data are collected into a database on the network, and machine learning is applied to detect wildlife [2]. The proposed system enables CSI to be collected easily, which could previously only be done using specialized equipment, and it enables existing wireless LAN systems to be repurposed, greatly reducing the cost of deployment. A dynamic demonstration of the system was conducted at the NTT R&D Forum 2018 Autumn, in which a wild boar stuffed animal and a plastic bottle representing a person were recognized, demonstrating the feasibility of the system (Fig. 3).

Fig. 2. Overview of wildlife detection system.

Fig. 3. Demonstration of proposed system.

* CSI: Information regarding the propagation path between transmitter and receiver antennas, including amplitude and phase information for each subcarrier when using orthogonal frequency division multiplexing.

4. Future prospects

Many of the visitors to the NTT R&D Forum 2018 Autumn were troubled by the agricultural damage caused by wildlife, so we intend to use the proposed system to establish technology to counter wildlife damage and also to expand the range of applications beyond wildlife, to detecting intrusions by people and objects as well.


[1] IEEE Std 802.11ac-2013: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications--Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz, Dec. 2013.
[2] T. Murakami, M. Miyazaki, S. Ishida, and A. Fukuda, “Wireless LAN-based CSI Monitoring System for Object Detection,” MDPI Electronics, Vol. 7, No. 11, 290, Nov. 2018.
Tomoki Murakami
Research Engineer, Wireless Access System Project, NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Dr.Eng. from Waseda University, Tokyo, in 2006, 2008, and 2015. He joined NTT Network Innovation Laboratories in 2008. His current research interests are high efficiency technologies for future wireless systems. He received the Institute of Electronics, Information and Communication Engineers (IEICE) Young Engineer Award in 2010, the IEICE Communication Society Best Tutorial Paper Award in 2014, the Institute of Electrical and Electronics Engineers (IEEE) AP-S Japan Chapter Young Engineer Award in 2014, the IEICE Best Paper Award in 2015, and the KIYASU-Zen’iti Award in 2015. He is a member of IEEE and IEICE.
Shinya Otsuki
Senior Research Engineer, Wireless Access System Project, NTT Access Network Service Systems Laboratories.
He received a B.E., M.E., and Ph.D. in communication engineering from Osaka University in 1993, 1995, and 1997. He joined NTT in 1997. From 1997 to 2008, he studied wireless access systems, wireless LAN (WLAN) systems, and wireless systems for Internet services in trains. From 2008 to 2011, he was involved in international standardization efforts in evolved packet core and services using Internet Protocol multimedia subsystems at NTT Service Integration Laboratories. He has been with NTT Access Network Service Systems Laboratories since 2011. He is a member of IEEE and IEICE.
Takafumi Hayashi
Group Leader, Senior Research Engineer, Wireless Access System Project, NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. from the University of Tokyo in 1994 and 1996. He joined NTT in 1996 and was involved in developing video communications and/or digital cordless phone systems. In 2001, he moved to NTT WEST, where he worked on WLAN systems. He has been with NTT Access Network Service Systems Laboratories since 2018 and is currently in charge of research and development of the future wireless communications system.
Yasushi Takatori
Project Manager, Executive Research Engineer, Wireless Access System Project, NTT Access Network Service Systems Laboratories.
He received a B.E. and M.E. in electrical and communication engineering from Tohoku University, Miyagi, in 1993 and 1995, and a Ph.D. in wireless communication engineering from Aalborg University, Denmark, in 2005. He joined NTT in 1995. He has served as a secretary of the IEEE Japan Council Awards Committee and as vice chairman of the WLAN system development project in the Association of Radio Industries and Businesses (ARIB). He was a visiting researcher at the Center for TeleInFrastructure (CTIF), Aalborg University, from 2004 to 2005. He served as a co-chair of COEX Adhoc in the IEEE 802.11ac committee from 2009 to 2010. He received Best Paper Awards from IEICE in 2011 and 2016. He was honored with the IEICE KIYASU-Zen’iti Award in 2016. He also received the IEEE Standards Association’s Outstanding Contribution Appreciation Award for his contributions to the development of IEEE 802.11ac-2013 in 2014. He is a senior member of IEICE and a member of IEEE.
Kazuo Kitamura
Project Manager, Executive Research Engineer, Networked Robot & Gadget Project, NTT Service Evolution Laboratories.
He received a B.E. and M.E. in materials science from Waseda University, Tokyo, in 1990 and 1992. He joined NTT in 1992. His current research interests include agritech.