Analysis on the application of narrowband Internet of Things (NB-IoT) in traffic infrastructure safety monitoring

Safety monitoring of transportation infrastructure should be a new and broad application scenario for NB-IoT. From the perspective of traffic management needs, safety monitoring of transportation infrastructure is an inevitable requirement for the comprehensive "measurability" of smart transportation, and it is also an inevitable requirement for the high-quality development of transportation. From the perspective of the industry, this is obviously a blue ocean and an undeveloped virgin land. It is a new battlefield and new growth pole for the large-scale development of the NB-IoT industry. There is demand from both the supply and demand sides, and it is technically feasible. Therefore, we have reason to be full of confidence and expectations for this.

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1. Introduction to Low Power Wide Area Network (LPWAN)

The emergence of LPWAN fills the gap in the communication layer of the Internet of Things (IoT) era. The network and the devices connected to it have the following characteristics:

1. Ultra-low power consumption

When the device communicates with the network, due to the small number of transmissions, low frequency, and the device is usually in sleep mode, the device battery power consumption is low, ensuring that the battery can continue to supply power for more than 10 years to meet the long-term maintenance-free needs. For example, the city's smart water meter is generally only awakened when the meter is read remotely at the end of the month. The data it transmits at a time is only a few KB, which has the characteristics of small data and low frequency.

2. Wide coverage and deep coverage

Regarding the network requirements, the connection coverage range of a single base station can reach more than ten kilometers. Through enhanced coverage, better signal penetration can be achieved in harsh environments, and the signal can be transmitted into the air and into the ground, basically eliminating the problem of signal coverage blind spots.

3. Large connection capacity

The device connection capacity of a single base station reaches tens of thousands or even hundreds of thousands. Compared with traditional cellular networks, the connection capacity has been greatly improved, which can effectively support the needs of the Internet of Everything.

4. Low cost and low bandwidth

On the one hand, the simplified design of terminal device chips reduces the overall cost of devices with built-in LPWAN standard communication modules. On the other hand, the small amount and low frequency of data transmission result in low traffic fees (connection fees) paid by application parties to network operators. For example, the world's first NB-IoT package launched by China Telecom costs only 105 yuan for 8 years. The average annual device connection fee of more than 10 yuan is only a fraction of the current 4G traffic fees of hundreds of yuan per year.

It should be said that low-power wide-area networks (LPWANs) make the vision of "Internet of Everything" possible.

The technical standards of LPWAN can be divided into two types, namely, licensed spectrum and unlicensed spectrum, depending on whether they are based on authorized use of radio spectrum. Among them, the famous licensed spectrum standards include NB-IoT and eMTC standards led by the 3GPP standardization organization, and the well-known unlicensed spectrum standards include LoRa and Sigfox standards.

2. Focus on Narrowband Internet of Things (NB-IoT)

Among many LPWAN technology standards, NB-IoT can stand out in my country and even take the lead, mainly based on the following reasons.

1. Strong support from national policies

On June 16, 2017, the Ministry of Industry and Information Technology issued the "Notice on Comprehensively Promoting the Construction and Development of Mobile Internet of Things (NB-IoT)", which clearly stated that 14 measures will be taken to comprehensively promote the construction and development of NB-IoT, and by 2020, 1.5 million NB-IoT base stations will be built and more than 600 million NB-IoT connections will be developed. The notice clearly stated that the construction of wide-coverage, large-connection, low-power mobile Internet of Things (NB-IoT) infrastructure and the development of applications based on NB-IoT technology will help promote the construction of a strong network and manufacturing country, and promote the development of "mass entrepreneurship, mass innovation" and "Internet +". This shows that NB-IoT has risen to the level of national strategic layout, and will surely lead the NB-IoT industry into a fast lane of comprehensive development.

2. Active layout of the three major operators

First, China Telecom has completed the deployment of the NB-IoT network, and 310,000 base stations across the network have been upgraded synchronously, building the world's largest NB-IoT network. At the same time, in terms of implementation, China Telecom has greatly improved the reporting success rate of water, electricity, gas and other meter readings in smart cities through the linkage optimization of the NB-IoT network and the Internet of Things platform, and reduced the low latency and other problems in the reporting process.

Secondly, China Unicom completed the construction of the NB-IoT core network in the third quarter of last year. By May this year, the scale of NB-IoT base stations exceeded 300,000, which can basically achieve nationwide coverage. This is the second NB-IoT network covering the whole country after China Telecom. In June last year, China Unicom released a new generation of IoT connection management platform. At present, the platform has exceeded 80 million connections and nearly 20,000 industry customers, with about 3-4 million new connections per month. It has become the world's largest single connection management platform. It is expected that by the end of this year, China Unicom's IoT connections will exceed 130 million.

Thirdly, China Mobile's NB-IoT network has been launched in 346 cities in 2017, achieving end-to-end large-scale commercial use. It is expected that in 2018, China Mobile's NB-IoT network will continue to expand its coverage to counties and cities across the country.

3. Dominance of mainstream telecom operators

First of all, NB-IoT is a technical standard promoted by the 3GPP standardization organization. Secondly, the world's mainstream communication operators such as Huawei, Vodafone, Qualcomm, Ericsson, Nokia, and ZTE participated in the formulation of the NB-IoT standard. The NB-IoT standard was finalized by the 3GPP organization based on the integration of the NB-CIoT technical solutions led by Huawei, Vodafone, and Qualcomm and the NB-LTE technical solutions led by Ericsson, Nokia, and ZTE. It can be said that NB-IoT is currently one of the most mainstream technologies in the field of low-power wide area networks.

4. Industry’s enthusiastic investment

After the issuance of the Notice by the Ministry of Industry and Information Technology in 2017, the development of China's narrowband Internet of Things is in full swing. The China NB-IoT Industry Alliance was established, bringing together the forces of NB-IoT industry chain chips, modules, equipment, platforms, operators and other parties to jointly build the NB-IoT industry chain ecosystem, jointly build a mature end-to-end industry chain, promote the rapid development and commercial deployment of the NB-IoT industry, and incubate business models in new ecosystems. Over the past year, according to the NB-IoT Industry Development Research Report released by the China Academy of Information and Communications Technology in April 2018, NB-IoT has been widely used or piloted in smart homes, smart agriculture, smart street lights in smart cities, parking lots, bus stops, water meters, gas meters, water service detection, gas monitoring, fire protection and other fields, showing a good development momentum. Huawei predicts that by the end of 2018, there will be 150 million connections in China's narrowband Internet of Things. As the scale of the Chinese market continues to expand, it will help reduce the cost of NB-IoT equipment and services, forming a long-term healthy development trend.

III. Demand for Transportation Infrastructure Safety Monitoring

The Ministry of Transport's 2017 Statistical Bulletin on the Development of the Transportation Industry shows that by the end of 2017, the national railway operating mileage reached 127,000 kilometers, and the total mileage of national highways reached 4,773,500 kilometers; at the end of the year, the national mileage of Grade IV and above highways reached 4,338,600 kilometers, the mileage of Grade II and above highways reached 622,200 kilometers, and the mileage of expressways reached 136,500 kilometers. At the end of the year, the national highways reached 358,400 kilometers, and the provincial highways reached 333,800 kilometers. The rural highway mileage reached 4,009,300 kilometers, including 550,700 kilometers of county roads, 1,157,700 kilometers of township roads, and 2,300,800 kilometers of village roads. At the end of the year, there were 832,500 highway bridges with a total length of 52,256,200 meters, including 4,646 super-large bridges with a total length of 8,267,200 meters, and 91,777 large bridges with a total length of 24,243,700 meters. There are 16,229 highway tunnels with a total length of 15.2851 million meters across the country, including 902 extra-long tunnels with a total length of 4.0132 million meters and 3,841 long tunnels with a total length of 6.5993 million meters.

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From the statistical information, the transportation industry presents the characteristics of many points, long lines and wide areas. At the same time, it is also a pillar industry for the development of the national economy. Many transportation infrastructures are built through mountains and across water. The geographical environment, geological conditions, topography and landforms are complex. When natural disasters such as floods and rainstorms occur, it is very easy to have dangerous situations such as landslides and collapses of slope protection slopes and subsidence of road surfaces and subsidence. Some highway pavements have been crushed by overweight and overloaded vehicles for a long time, and overloaded operation has caused premature damage to the road surface. The safety problems of transportation infrastructure generally do not occur suddenly. There are advance signs. They are gradually accumulated from small risks and finally become major risks, causing economic losses such as traffic blockage and road property damage. If the safety status of transportation infrastructure can be monitored in real time, and hidden dangers can be discovered, warned and dealt with in time through sensor monitoring equipment deployed on the roadside, roadbed, bridges, tunnels and other locations, it is possible to prepare for a rainy day and prevent them before they happen. It can effectively prevent the occurrence of dangerous situations such as landslides and collapses, and ensure that on the basis of the safety of transportation infrastructure, people and goods can flow smoothly throughout the transportation process.

However, the current situation is obviously not optimistic. Except for highways, important bridges, and long tunnels with relatively complete electromechanical facilities, most facilities cannot realize the comprehensive deployment of sensor equipment for real-time monitoring. Instead, they rely solely on routine inspections by maintenance departments to discover hidden dangers, which is inevitably inefficient, and some hidden dangers are not easy to be discovered. One of the important reasons why a large number of sensor equipment cannot be deployed to monitor transportation infrastructure in real time is that the cost is too high. First, the equipment cost is high, second, the deployment cost is high, and third, the operation and maintenance cost is high, especially in ordinary national and provincial trunk roads, county and rural roads, which have neither power supply conditions nor network conditions (using mobile operator network traffic fees is too expensive, and signal coverage is blind spots), which makes it even more difficult.

IV. Application of NB-IoT in traffic infrastructure safety monitoring

At the 2017 Communications Exhibition, a demonstration of NB-IoT applied to landslide monitoring and early warning was carried out. Once a geological disaster occurs, multiple sensors with built-in NB-IoT communication modules monitor abnormal conditions in the mountain, trigger data upload, and provide real-time information warnings to users near the disaster area through community broadcasts, and remotely inform government, meteorological, public security and other industry authorities. The feasibility of related applications of NB-IoT+Beidou to monitor mountain conditions has also been discussed in the industry.

Inspired by this, the author believes that it should be technically feasible to apply NB-IoT technology to the safety monitoring of transportation infrastructure. Sensor equipment based on NB-IoT communication modules is low-cost, easy to deploy, and long-term maintenance-free. NB-IoT base stations have strong coverage capabilities, and connections are not restricted by geographical conditions. The connection capacity is large, which can meet the requirements of densely deployed sensor equipment. Relying on the operator's NB-IoT network for data transmission, the connection cost is low. Therefore, a large number of sensor devices with built-in NB-IoT communication modules can be deployed in transportation infrastructure such as road embankment slopes, bridges and tunnels to monitor their deformation. Once the sensor equipment detects that the safety status of these transportation infrastructures has reached the warning value, it will immediately trigger the sensor to issue a warning to the monitoring platform, and then take corresponding disposal measures.

At present, although the industry is enthusiastic about NB-IoT, the application scenarios are still too limited, mostly focusing on smart water meters, smart street lights, smart trash cans, smart smoke detectors, etc. Traffic infrastructure safety monitoring should be a new and broad application scenario for NB-IoT. From the perspective of traffic management needs, traffic infrastructure safety monitoring is an inevitable requirement for the comprehensive "measurability" of smart transportation and the high-quality development of transportation. From the perspective of the industry, this is obviously a blue ocean, an undeveloped virgin land, and a new battlefield and new growth pole for the scale-up of the NB-IoT industry. There is demand from both the supply and demand sides, and it is technically feasible. Therefore, we have reason to be full of confidence and expectations for this.