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  • Rian Sullings

NB-IoT Water Metering


New opportunities are being created for digital water metering through the emergence of NB-IoT technology. This enables ‘things’ such as water meters and other sensors to communicate wirelessly with existing cellular infrastructure while keeping energy consumption low enough to operate on batteries for 10 years or more.

Following Telstra’s official announcement of the commercial release of NB-IoT and their support for water utilities and digital water metering, water suppliers and their communities stand to realise far greater benefits, reliability, and performance from digital metering to improve water security, water network and operational optimisation, and customer insights.

NB-IoT (Narrow Band - Internet of Things), is a globally standardised wireless communication technology operated by traditional telcos around the world and in Australia by Telstra, Optus, and Vodafone. The standard was frozen in 2016 and the technology has been rigorously tested and is now rolling out across the country by each telco in the lead up to their fast approaching commercial launches. This will bring tremendous benefits to the water industry where many assets have no local power supplies therefor must operate on batteries and at low cost. Many Australian water utilities have been involved in digital water metering and other NB-IoT pilot projects for the past 2 years as they realise the value and rush to adopt innovative solutions to long standing problems of water security and a lack of data on their network operations.

The key benefits of NB-IoT for digital water metering over 3G/4G and other wireless technologies include:

  • Existing coverage from major telco infrastructure

  • Greater range and signal penetration than 3G/4G

  • Lower energy consumption than 3G/4G for 10+ year battery life

  • Open standard based wireless and data format protocols

  • ‘Message received’ acknowledgements for high reliability

  • Greater data packet sizes to enable additional functionality over other LPWANs

  • Integrity of licenced radio spectrum

  • Configuration over the air

  • High level of security on the air and in the cloud

  • Lower connectivity and total operating costs than 3G/4G

NB-IoT can be categorised as an LPWAN (Low Power Wide Area Network), which is a wireless technology type that caters to applications where small amounts of data are needed to be delivered over the air with high efficiency. While 4G on our phones is great for high speed video streaming, the high energy consumption makes it impractical for digital water metering. This is where NB-IoT and other LPWANs come in. I’ve covered new LPWAN technologies for digital water metering more broadly here (link).

Perhaps the most closely related technology to NB-IoT is Cat-M1 which serves as a precursor to NB-IoT and has seen success in smart electricity metering. The trend towards increasingly more energy efficient and low data volume networks continues from 4G/3G to Cat-M1, and now on to NB-IoT.

Coverage, Range, and Penetration

One of the greatest advantages of NB-IoT over other LPWAN technologies is that it operates on existing cell towers, usually requiring only a software update to be enabled. With over 20,000 3G/4G basestations (a.k.a cell towers) across Australia, this instantly makes the major telco networks the largest LPWANs in the country and among the largest in the world at around 2.5 million square kilometres. At around $5,000 to $10,000+ each to establish basestations for other LPWAN technologies, NB-IoT is a challenge to match.

In addition to the quantity of basestations, NB-IoT also offers greater range and penetration than the 3G and 4G networks that we’re accustomed to. To give an indication of this, let’s use the town of Birdsville, Queensland as an example. Why Birdsville? It’s a small regional town, with very few cell towers and is mostly flat which makes it easy to directly compare radio technologies. We can use the publically published Telstra 3G/4G and Cat-M1 coverage maps. NB-IoT offers even greater range than Cat-M1 as we will see clearly once the detailed and navigable coverage maps are officially released by the telcos. By overlaying the maps of the Birdsville 3G/4G coverage with Cat-M1, we can see the significant advantage that Cat-M1 / NB-IoT offers.

The overlay above shows that in a largely flat and unobstructed environment, LPWAN networks such as Cat-M1 and NB-IoT offer significantly greater range and areas of coverage than traditional 3G and 4G networks using the same basestations. In this example, we can see that the radius of 4G coverage extends around 20kms from the basestation, 3G extends 20-40kms, and Cat-M1 (similar to NB-IoT) extends 60 to 80kms. This provides additional coverage to rural and outer-urban areas and enables larger deployments of digital water meters. In higher population areas this also means that there is more overlapping coverage from multiple basestations which further enhances quality and reliability of connectivity.

In addition to further range, NB-IoT also has greater signal penetration through physical obstructions thanks to its 20dB margin improvement over 3G/4G. In real world terms this means that if you are in a building with floors below ground, and your phone losses connectivity on the 1st basement floor down, an NB-IoT water meter may still have connectivity down to the 2nd basement floor or further.

It’s also common for water meters to be installed in pits just below ground level with concrete or steel checker-plate lids, and in the core of apartment buildings where there is a lot of concrete and steel reinforcement. NB-IoT is designed specifically to address these challenges and early pilots have shown results of 99.5% and higher success rates for delivery of meter readings from pits and apartment buildings.

Energy Consumption

NB-IoT is intended specifically to deliver small data packets with ultra-low energy consumption to achieve 10+ years of battery life. This is vastly different in principal to the 3G and 4G networks that we use for smartphones and are intended for high data volumes and high speeds. While a smartphone with average use will consume 7 to 8 Watt hours per day, an NB-IoT water meter will consume less than 0.01 Watt hours per day.

This new level of low energy consumption is one of the key factors in making NB-IoT an economically viable solution for digital water metering. Short battery life has made 3G impractical for large scale metering deployments, but now with NB-IoT this barrier is removed. An NB-IoT device will consume 2 to 5 times less energy than an equivalent 3G device when undertaking the same tasks, in the same environments and therefor achieves significantly longer battery life.

The operation of the radio components is the highest energy consumption task of an NB-IoT water meter so minimising the work load is the key to achieving long battery life. NB-IoT has many features which accomplish this.

When a smartphone makes first contact with a cell tower, the phone and the tower exchange a series of messages to introduce themselves before they can move on to the general sending and receiving of emails, Facebook feeds, and other data. The phone and the towers continue to introduce themselves over and over again to check that they are still in contact. This handshaking processes, also known as ‘attaching to the network’, consumes energy. NB-IoT addresses this with Power Save Mode. Instead of spending precious energy on attaching to the network every time data needs to be sent, NB-IoT devices are able to simply wake up and start talking.

Another benefit of greater range and penetration is that all sending and receiving of data requires less time and energy. Just like how smartphones transfer data faster when they have full signal bars, NB-IoT devices also run more efficiently where the quality of connectivity is greater. Wherever signal is lower, more energy is required for the device to connect with the network which increases the rate of battery decline. As NB-IoT has generally superior range and penetration than 3G / 4G and many other LPWAN technologies, it benefits from the reduced work required of the radio components and there for less energy consumption.

Open Standards

Many past wireless technologies for digital water metering have been proprietary, and often only supported single-vendor solutions. This has been favourable for the technology vendors, but not so much for the water utilities and the end users.

The 3rd Generation Partnership Project (3GPP) facilitates the global standardisation of mobile technologies including 3G, 4G, and now 5G. The 3GPP has also standardised NB-IoT since 2016 with the involvement of telecommunication giants such as Ericsson, Nokia, and Huawei. Since standardisation, NB-IoT has been piloted extensively, including Australia’s own South East Water, who were among the first utilities in the world to deploy the technology for water metering and cite the open standard nature as a key attraction.

In addition to the wireless network being open standard, there are also open standards for the data that the meters deliver. The leading protocol for digital water metering on NB-IoT is Light-weight Machine to Machine (LwM2M). LwM2M is open standard an application protocol, meaning it is a publically published set of conventions on the way data is arranged when it delivered between devices and software applications. Anyone can visit the Open Mobile Alliance website to see the full details of the protocol and utilise it to develop devices and software.

Licenced Spectrum

Wireless frequencies for LPWANs can be placed broadly into two categories; licenced, and un-licenced. Each country or region in the world has local regulations on which frequency bands require a licence to operate on and which do not. In Australia, the regulatory body ACMA provides licences to telecommunication providers to use certain frequencies. These licences are acquired by each telco for 6, 7, and 8 figure sums of money, often through auction processes, and are used for multiple technologies including 3G, 4G, Cat-M1 and now NB-IoT. Licenced spectrums are more tightly regulated and managed to ensure reliability, making them less susceptible to interference.

The most common un-licenced frequency for LPWAN networks in Australia is the 915MHz band which is used by Sigfox, LoRaWAN, and other smart water metering technologies. NB-IoT however, is most commonly operated on the licenced 700MHz band as used by Telstra and Optus. As a rule of thumb, the lower the frequency, the greater the range and the penetration of the wireless communication will be. Couple this with licence protected spectrum and the result is a highly robust communication network.

Security

With the scale of digital metering increasing and the high value of the data being used for billing, fault identification, and network planning, security is a critical aspect of any digital water metering system. NB-IoT makes use of multiple layers of telco grade security tools and features similar to 3G/4G smartphones to ensure that the data and infrastructure is protected.

In addition to authentication and encryption throughout the various layers of the stack, digital water meters can be deployed using a private Access Point Name (APN). This means that meters are not connected via the public internet like most consumer devices, but rather communicate with the telco network via a private system. The benefit of this is that only devices with prior authorisation can connect and interface with the meters, preventing unauthorised access over the internet. The data is then delivered from the telco system to the utility or users’ applications and data storage via a Virtual Private Network (VPN), which uses encryption methods to provide a secure pathway for data to travel between the two locations.

While IoT devices generally have less processing power and communicate with much smaller data-packets than smartphones, computers, and other devices, the ability to achieve the appropriate high level of security is not compromised.

Bi-Directional Communications

Bi-directional communications means that devices can deliver data to the network, and the network can also deliver data back to the devices. This enables both advanced functionality and high reliability. Some of the benefits of bi-directional communications include;

Acknowledgment of Successful Transmissions: each time the meter successfully transmits its payload of meter readings to the network, the network will send a small message back to notify the device that the readings were received. The device can therefor reattempt to send its payload if it does not receive an acknowledgement after any transmission.

With acknowledgements, it is readily possible to achieve 100% successful receipt of meter readings, even in very low or inconsistent signal scenarios. Without acknowledgements, digital water meters cannot ‘know’ if their meter readings have been successfully received and therefor are not ‘smart enough’ to attempt to retransmit data if required.

Let’s use a real world example to demonstrate the difference between two meters recording the same water use. Meter 1: Generic LPWAN meter recording readings at 1 hour intervals, uploading each reading each hour. This system does not have acknowledgements and the meter therefor does not have retransmission capabilities.

Meter 2: NB-IoT meter recording readings at 30 minute intervals, uploading all intervals in a batch once per day, and also uploading upon events that the local CPU recognises such as leaks or high flow. This meter waits for acknowledgements and reattempts uploads whenever it is unsuccessful.

The below graphs show the water use of an office building over a 4 day period. A below-ground leak starts on the morning of the Tuesday at a rate of 20L/min (equivalent to three taps running full bore, and a water cost rate of $3,300 per month). The NB-IoT water meter sends a leak alert to the facility manager. The leak runs until Thursday morning when it is physically found and rectified.

The meter using NB-IoT experiences a 30% unsuccessful transmission rate, however the meter ‘knows’ this and retransmits its data at pre-set intervals until it receives an acknowledgment. The result is that even with only a 70% success rate, all data is back-logged and then successfully delivered.

The generic LPWAN meter also experiences a 30% unsuccessful transmission rate but it is not looking for acknowledgments and does not attempt to retransmit lost data. The readings in these unsuccessful transmissions are lost forever. When the data is shown on a graph, it’s clear that water use increased on Tuesday compared to Monday but with 30% of the data missing, it is difficult to tell if the increased water use is due to a base flow such as a leak, or if it’s due to short periods of ON/OFF high flows.

The office also has much smaller leak which has been running for some time. Maybe this leak is not enough in terms of water cost to call a plumber, but maybe it’s causing mould to spread under carpet somewhere in the building. This is obvious on the NB-IoT graph but is practically undetectable on the generic LPWAN graph.

With greater detail and reliability of data comes greater understanding and insights into water use. With these greater insights, it is easier to make informed decisions towards real-world actions to achieve outcomes and improvements.

Configuration Changes Over the Air: commands to change configuration can be placed on the device management server for the meter to receive when it connects to the server to deliver its meter readings and other data. These commands can be used to change various parameters and settings such as the meter reading interval, the transmission interval, the transmission schedule (what time of day it reports), leak alarm thresholds, turn auxiliary sensors on/off, change network settings, and more.

Firmware Over the Air: send new firmware files to the device over the air to enable remote updates. This can be used to address network changes or issue security patches. This can prove advantageous, especially for devices which will operate remotely for 10+ years.

Higher Data-rate Enables Detailed Data and Additional Sensors

Many technologies used for digital water metering offer extremely low data-rates and are therefore constrained by limitations on how much data can be transmitted at a time. A generic LPWAN meter may only support 1, 2, or 3 meter readings per transmission. For this reason, many metering systems are only capable of delivering hourly interval meter readings and very little else.

The data-rate of NB-IoT is multiple times higher than other LPWAN technologies which allows it to send detailed meter reading data. For example, NB-IoT meters can easily deliver a full day of 30 minute interval data in one packet, along with many other parameters.

This ability to send greater volumes of data also enables the use of additional sensors such as water pressure. By fitting these additional sensors to digital water meters, further value can be realised by utilities and other users. Pressure sensors can be used to ensure compliance with customer pressure requirements, and also to determine the location of pipe breaks in the water distribution network.

The above image shows a drop in pressure in a specific area identified by digital water meters equipped with pressure sensors. With even just a small percentage of meters fitted with pressure sensors, network issues such as breaks and bursts can readily be identified. Deploying dedicated pressure sensing devices throughout a water supply network would require significant investment. By fitting these sensors into digital water meters and strategically placing them throughout the network, high value data can be acquired with minimal effort and cost.

Pricing of Connectivity

The cost of connectivity is a key factor of the business case for digital water metering, especially for utility-scale deployments. As NB-IoT moves from pilot to production, operators around the world have started publically releasing pricing for connectivity.

T-Mobile (USA) – USD 6.00 (AU$8.22) per year

Telkomsel (Indonesia) – IDR 15,000 (AU$1.39) per year

Deutsche Telekom / 1NCE (Germany) - € 1.00 (AU$1.61) per year

China Telecom (China) – CNY 20.00 (AU$4.00) per year

Some of these announcements have conditions attached such as minimum order quantities, multi-year contracts, or expiry dates on introductory offers. All include sufficient data volumes to support digital water metering with meter readings logged more often than hourly. While the Australian telcos are expected to start openly announcing commercial pricing later this year, perhaps even this month, international pricing shows that NB-IoT will meet the expectations of ultra-low connectivity. The low connectivity costs can even be embedded in the capital investment in the meter, similar to how car makers like BMW and Tesla include 4G connectivity for in-car entertainment in the price of their vehicles.

Keep in mind that previous digital water metering technologies usually have on-going costs too and also required investment in the procurement, installation, and on-going management of radio infrastructure, often based on single-vendor and proprietary technologies. This has left water utilities and end-users holding the responsibility for radio infrastructure which is outside their core focus and often outside their skillsets. With NB-IoT, the connectivity fee per device covers all costs associated with the radio infrastructure, leaving the user free to focus on meaningful data-based decisions and actions.

With all digital metering, the connectivity cost is only one component. Other costs must be considered for hardware, installation, project management, data hosting, software, analytics, and taking actions from the data-driven insights.

Future of NB-IoT

With the 2G sunset still in recent memory, and a rapidly evolving world of technology, it’s fair to question what the future of NB-IoT will look like. Unlike 2G, NB-IoT is intended specifically for use cases where devices must operate with little or no maintenance for 10 years or more. Unlike consumer tech like mobile phones, most NB-IoT devices will be deployed for commercial and industrial purposes with simple, long-term use cases. There is therefore no driver to replace the device or network every few years simply because a newer model with a shiny new feature or a faster internet speeds comes along. It is also intended to enable the connectivity of billions of everyday objects from council waste bins to streetlights, and of course smart water meters, with the later categorised as ‘critical infrastructure’. To this extent, the telcos are obligated to maintain the network for as long as their customers, including government and water utilities, will require it and pay to use it.

In much the same way as we’ve seen 4G speeds increase as the technology matures, NB-IoT will also continue to be refined while maintaining standards and compatibility. Future generations of radio modules from global suppliers such as u-blox and Quectel will bring improvements in energy consumption and serve to further improve the battery life and consequentially many business cases for digital water metering in the coming years.

With most technologies, as they mature, industry becomes better equipped and more efficient at delivering solutions that make use of them. NB-IoT, which is designed with low cost and simplicity in mind, will as a whole become even lower cost and simpler to deploy and manage as time goes on.

NB-IoT has come a long way since standardisation in 2016 to multiple commercial releases around the world in 2018. After building up for the past few years, it is now rapidly gaining traction in digital water metering as highly reliable no-compromise solution for low cost, high volume deployments.

Original article by Rian Sullings, posted on rian.tv.

rian@rian.tv

#2018 #AMI #AMR #IoT #SmartWaterMetering #LPWAN #NBIoT #SmartWater

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rian@rian.tv

Melbourne, Australia

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