IOWN All-Photonics Network with Optical Fiber Sensing Functions Achieves Wide-Area Traffic Flow Monitoring

TOKYO, Oct 1, 2024 - (JCN Newswire) - NTT Corporation, NTT EAST Corporation, NTT WEST Corporation and NEC Corporation have jointly devised a connection configuration to add optical fiber sensing functions to the IOWN All-Photonics Network (APN)(1). By applying this configuration to multiple routes of optical fiber for communication already laid underground (in the service area of NTT WEST in Osaka City), we have demonstrated that it is possible to grasp area-wide traffic trends using optical fiber sensing, and to visualize and analyze traffic conditions in real time.Optical fiber sensing in the IOWN APN enables low-cost, prompt, and flexible expansion of urban monitoring across a wide plane. In the future, we will promote R&D and co-creation activities toward the establishment of more advanced optical fiber sensing that will contribute to solving social and regional issues by implementing optical fiber sensing in society and exploring usage scenarios based on these results.

1. Background

Optical fiber sensing, which enables the use of optical fiber for communication as a sensor, is expected to create new social value as demonstration tests and introduction of technologies for detecting construction vibration [1], supporting road snow removal decisions [2], and improving the efficiency of communication facility maintenance and operation progress [3]. The combination of IOWN and optical fiber sensing enables advanced data analysis by taking advantage of the high-speed transfer of large amounts of data by APN, and is thought to promote the use of sensing data. Furthermore, by using the optical path selection function of the APN-Gateway (APN-G) 2, which composes APN, a single optical fiber sensing device can measure multiple existing communication optical fibers connected to APN-G. Thus, optical fiber sensing in conjunction with the IOWN APN has the potential to realize low-cost, prompt and flexible urban monitoring across a wide plane (Figure 1), and these advantages are described in the IOWN Global Forum publication [4].With the aim of social implementation of optical fiber sensing using IOWNs, the four companies constructed a connection configuration that enables optical fiber sensing via APN-G, and conducted wide-area traffic flow monitoring on open roads. Several examples of traffic flow monitoring using optical fiber sensing have been reported [5], but this is the first case of wide area monitoring along multiple open roads.

Figure 1: Wide-Area Optical Fiber Sensing Using IOWN

2. Point of the technology

Construction of a connection configuration that can add optical fiber sensing functions to the APN-GSince optical fiber sensing is measured using the round trip propagation of light, it is necessary to connect the optical fiber sensing instrument in a configuration that avoids devices (such as optical amplifiers) placed on the optical path of the APN that transmit light only in one direction. For this reason, we have devised and constructed a connection configuration between the APN-G and an optical fiber sensing device that uses a directional-coupler (optical circulator) to avoid a device (optical amplifier) that transmits light only in one direction of the APN-G and to extract the round trip sensing light (Figure 2).Utilizing optical fiber for communication installed in underground pipelinesSince the measurement is possible without any modification to the communication optical fiber cable or underground conduit, it is possible to obtain sensing data from a wide area by effectively utilizing existing facilities.Optimized vehicle speed analysis for open roadsUnlike long straight roads such as expressways, we conducted an analysis so that the speed and number of vehicles can be detected on short straight roads such as open roads with many intersections.

Figure 2: Connection Configuration for Implementing Optical Fiber Sensing via IOWN APN3. Results of the joint experiment

Five vibration sensing devices were connected to the APN-G to simultaneously measure surface vibration on five routes (Wiring totaling 37 km, covering 8 km in four directions) of existing optical fiber communication cables (laid underground on roads in Osaka City). By analyzing this traffic vibration with a vehicle speed analysis algorithm, we were able to visualize in real time the average vehicle speed of vehicles on open roads, the amount of traffic on the road and its changes over time in a 200 m mesh granularity (Figure 3). In addition, it was confirmed that the results of the analysis of vehicle speed and number of vehicles tended to agree with the correct data measured at five sites. (Demonstration period: December 2023 to January 2024: Data measurement; February to July 2024: Analysis and verification of usefulness).

Figure 3: Wide-Area Monitoring Results of Traffic Flow

Traffic flow meters on ordinary roads are installed at intervals of several kilometers only on major lines, requiring the permanent installation and operation of a huge number of sensors. However, optical fiber sensing linked to APN-G can flexibly monitor arbitrary points on optical fiber routes that extend to every corner of a city. It is expected to be used as a new social infrastructure, such as traffic congestion detection and prediction using traffic information collected from a wide area and application to urban traffic planning.The connection configuration of the optical fiber sensing device to the APN-G used in this study was adopted in the IOWN Global Forum publication [6].

4. Role of each company

NTT: Devising and constructing a connection configuration to provide sensing functions to IOWN APNsNTT EAST: Calibration of vehicle speed and vehicle count positionNTT WEST: Selection of traffic vibration monitoring sites and selection and provision of facilities for demonstration testsNEC: Provision of APN-G and implementation of optical fiber vibration measurement and vehicle speed analysis

5. Outlook

Based on these achievements, we will continue developing the optical fiber sensing market using APNs collaborating with other companies, including discussions at the IOWN Global Forum. In addition, along with the nationwide expansion of APN, we aim to realize low-cost, wide-area urban monitoring that enables flexible sensing at arbitrary locations as long as it is connected with optical fiber, and does not require the installation and construction of permanent outdoor devices. In the future, we will promote R&D and co-creation activities aiming to solve social and regional issues through the social implementation of optical fiber sensing, with a perspective of various applications through urban monitoring, such as infrastructure monitoring, disaster prevention, and the realization of infrastructure design incorporating nature in urban planning.

Reference
(1) NTT EAST News Release, “NEC, Kashima, and NTT EAST succeeded in detecting construction vibration using the world's first optical fiber for communication," August 2023 https://www.ntt-east.co.jp/release/detail/20230824_01.html
(2) NTT News Release, “World's first vibration sensing technology using telecommunication optical networks for making road snow removal decisions in heavy snowfall areas,” November 2023 https://group.ntt/en/newsrelease/2023/11/09/pdf/231109aa.pdf
(3) NTT EAST News Release, “Start of the operation of communication facility maintenance using optical sensing technology toward the IOWN era," May 2022 https://www.ntt-east.co.jp/release/detail/20220516_01.html
(4) IOWN Global Forum Functional Architectures “Fiber Sensing for Open APN 1.0" https://iowngf.org/wp-content/uploads/2023/04/IOWN-GF-RD-FS_for_Open_APN-1.0.pdf
(5) NEC News Release, " NEC provides AI-based traffic monitoring system with fiber-optic sensing technology for NEXCO CENTRAL," May 2022 www.nec.com/en/press/202205/global_20220524_01.html
(6) IOWN Global Forum Functional Architectures “Fiber Sensing for Open APN 2.0" https://tinyurl.com/4ywj7bem

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