2. Focused Research (1)IIJ’s Efforts to Promote LoRaWAN® in
Agricultural IoT
2.1 Introductionsin the field, which has involved installing base stations, eval-

IoT initiatives are expanding rapidly across a whole range ofuating data link performance, and the like.

fields. As the use cases multiply in manufacturing, healthto agriculture. Agriculture is a core industry and backbone

2.2 Testing IoT-based Paddy Field Water Managementof the nation, yet it is plagued by issues including serious

With support from the National Agriculture and Food

workforce aging and a lack of successors as well as poor

Research Organization’s special scheme project on vi-

profitability. To address these issues, Japan’s Ministry oftalizing management entities of agriculture, forestry andAgriculture, Forestry and Fisheries has made “smart agricul-

fisheries, IIJ has been developing and testing a low-costture” a keyword and is actively engaged in demonstration

ICT water-management system that facilitates labor saving

testing nationwide.

in the area of paddy field water management. This year,

care, automobiles, and other areas, IIJ has turned its eye

we launched Mizukanri Pack S [Water Management Pack
Against this backdrop, IIJ is looking at whether it can lendS], which packages together the results of these efforts asa hand to ease the burden on Japanese agriculture and help

a set of paddy field sensors that measure water levels andmake it more economically viable. Our track record so far in-temperature, a wireless base station, a smartphone water

cludes developing paddy field sensors that use LoRaWAN®,

management app, and cloud services (Figure 1). The paddy

a new wireless communications technology that IIJ is fo-

field sensors and wireless base station use LoRaWAN® to

cused on.

communicate. A package that automates water management is also available, comprising the Mizukanri Pack S

The biggest issue facing IoT for agriculture is enabling data

paddy field sensors and base station as well as a valve that

communications. Here, we take a deep dive into the know-

automatically controls water volume based on water levels

how we have amassed through experience and trial-and-error

measured by the sensors.

M onitor water level & tem perature remotely from home,
workshop, etc.

IIJ water
management
platformfor paddy fields
Mizukanri app

Sensors collect paddy field
wa te r l eve l / te m p e r a t u r e
data.

LTE

Easily installed in home orworkshop. Listens to multiple
sensors.

LoRaWAN®

Wireless base station(LoRaWAN®)

Figure 1: Mizukanri Pack S Saves Labor in Paddy Field Water Management

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2. Focused Research (1)IIJ is a communications carrier, so working in an unfamiliar

2.3 A Single Base Station Can Cover Several kmwith LoRaWAN®

area like agricultural IoT and venturing outside of our area

2.3.1 About LoRaWAN®

of expertise to develop new devices like paddy field sensors

LoRaWAN® is a wireless networking specification that uses

was challenging and a constant struggle. We detail thesea spread spectrum modulation technique called LoRa®,

efforts in “The IIJ Stories” .

developed by Semtech. Although LoRa® communication*1

speeds are slower than Wi-Fi and BLE, it can cover an evenIn this report, we focus on the wireless base stations, part of​​wider range than LTE, as illustrated in Figure 2. It also

IIJ’s business domain, and describe efforts to promote use

makes it possible to create low-power devices that canof LoRaWAN® in agricultural IoT. Although it is part of ourcommunicate for several years on battery power alone.

business domain, we were inexperienced in many respects

Mizukanri Pack S paddy field sensors take advantage ofand faced a range of challenges. In particular, we travelledthese characteristics to cover an area of several kilometers

frequently to measure data link status, from Hokkaido inwith a single base station and operate throughout an entire

the north down to Kyushu in the south. Before delving into

growing season on two AA batteries, with no need for thethe knowhow those efforts produced, we first provide somebatteries to be replaced.

background knowledge on LoRaWAN® and how it is distinct
from other LPWA standards.

High

LTE
Wi-Fi
BLE

Mission critical Outdooruse caseHigher Power

Video / Voice
Consumer IoT

Bandwidth

Sensors, Actuators and Tags
Lowest Power and Lowest Cost
Low
Short

Range

Long

Figure 2: LoRa® Relative to Other Standards*1

The IIJ Stories | IoT is changing the future of Japanese agriculture by supporting rice farmer work-style reforms (https://www.iij.ad.jp/interview/03.html, in Japanese).

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Some LoRa® wireless networks use proprietary proto-

used within the coverage areas without the need to installcols, but the standard is LoRaWAN®, specified by the

your own base station.

LoRa Alliance®, comprising over 400 member companies
including IIJ. LoRaWAN® certificated devices are intercon-

Sigfox is very inexpensive, with usage fees as low as 100

nectable, opening up a wide range of choice with respect

yen per device per year (depending on the number of de-to sensors and other connected devices from different

vices under contract), and covers 95% of the population as

manufacturers.

of January 2020. In basic terms, it allows for uplink onlywith payloads limited to 12 bytes and the number of mes-

Figure 3 shows the structure of a LoRaWAN® system. The

sages per day limited to 14. Yet it is the leader in Japan indevices communicate via gateways and LoRaWAN®. The

terms of number of devices deployed, with, for example,

gateways connect to a network management server, called

850,000 compatible devices that use these features for tak-a network server, via LTE, Wi-Fi, or wired Ethernet. The

ing gas meter readings already slated for installation.

network server provides management capabilities, including device activation, elimination of duplicate data received

The LTE-M standard is developed by 3GPP, and three mo-from the same device via multiple gateways, control ofbile carriers provide LTE-M services in Japan: NTT Docomo,

communication routes to the application server for eachKDDI, and SoftBank. Using a bandwidth of 1.4MHz allows

data payload, and variable data rate control. The application

bidirectional communication of up to 1Mbps, and it also

server communicates with the network server via a REST

supports FOTA (Firmware Over-The-Air) remote device firm-

API or the like, and stores data received from end-devices,

ware updates. It also supports handover switching of baseprovides application-based visualizations, and controls de-stations when on the move, so it can be used in much thevices according to user command or automatically according

same way as regular LTE. However, if used only on carrier

to preset criteria.

networks, the data charges are 100–150 yen per device up
to 10,000 devices, which is far more expensive than Sigfox.

2.3.2 Features Compared with Other LPWA Standards
LoRaWAN® is a type of LPWA (low-power wide-area) net-

Some carriers provide their own LoRaWAN® base stations

work. These networks are characterized by low powerand base stations shared among users, but generally you

consumption, low bit rates, and wide area coverage. Many

need to install your own base station. Low-price LoRaWAN®

other LPWA wireless networks exist, including Sigfox andgateways are available that are similar to mass-mar-

LTE-M. Communications carriers operate base stations na-

ket LTE-capable IoT gateways, like the Kiwi Technology

tionwide for Sigfox and LTE-M, and the networks can be

TLG3901BLV2 included in Mizukanri Pack S.

Ordinary network server model

Generally built in the cloudDeviceGateway

Application

DeviceNetwork server
DeviceApplication
serverGateway

Application

DeviceFigure 3: Overview of a LoRaWAN®-based System

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2. Focused Research (1)Having to install your own base station puts LoRaWAN®

2.4 Challenges in Promoting LoRaWAN®
for Agricultural IoT

at a disadvantage to Sigfox and LTE-M in terms of equip-

So far we have discussed:

2.3.3 Applications Suited to LoRaWAN®

ment and installation costs. But an advantage is the ability
to add base stations to reach areas not covered by out-

• Features of LoRaWAN® and suitable applications

door base stations, such as basements and inside buildings.

• Advantages of LoRaWAN® in agricultural IoT

And because there are no data charges for communications
between devices and the gateway, the cost benefits are

So what challenges do we face in popularizing LoRaWAN®

considerable if only a few base stations are used to serve a

for agricultural IoT?

large number of devices. LoRaWAN® is particularly suitable
for low-cost applications that involve multiple battery-pow-

2.4.1 Installing Inexpensive Outdoor Base Stations

ered devices installed in large buildings, such as factories,

I was involved mainly in base station design as part of the

shopping centers, and offices.

three-year paddy field water management IoT demonstration
testing project, and based on my experience, the biggest is-With no downlink restrictions, LoRaWAN® is also effective

sues are finding places to install base stations and obtaining

in agricultural IoT, including paddy field water management,a power supply.

when there is a need to control devices like water supply
valves. Ensuring profitability in agricultural IoT can be dif-

The TLG7921M is a waterproof outdoor LoRaWAN® gateway

ficult if expensive devices and services are used, so thewith strong wireless performance, so a single unit can coveradvantages of LoRaWAN® and inexpensive equipment comea wide area if installed in an elevated spot, such as a rooftop

into play here to enable low-cost services even when using

or mountain. But it is more expensive than indoor LoRaWAN®

multiple devices of different types. A range of LoRaWAN®-

gateways, and the cost of installation, including wiring, iscompatible devices from different manufacturers are alreadyalso high, so it is an expensive option unless installed on aavailable for agricultural IoT, including paddy field sensors

decent scale (e.g., rolled out across an entire region).

and water supply valves for paddy field water management,
weather sensors for measuring rainfall and temperature, andKiwi Technology’s TLG3901BLV2 is a very cheap LoRaWAN®

soil sensors for measuring soil temperature and moisture.

gateway included in the Mizukanri Pack S. It is an indoor

These can all be accommodated by a single LoRaWAN®

device intended for installation in homes or offices of ag-

base station. Another advantage is the ability to set up

ricultural businesses, but offices and homes are often far

your own base stations to provide coverage in areas wherefrom the paddy fields where the sensors are installed, andcarrier-operated base stations can struggle, such as moun-the data links can be unstable. Installing them in private

tainous terrain.

homes with a power source near the fields would work, but

Figure 4: Kiwi Technology’s TLG3901BLV2© Internet Initiative Japan Inc.

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this is not all that realistic since users themselves would

2.5 Solutions to the Issues

have to negotiate with property owners about how much

So far, we have explained that promoting the use of

to pay for the electricity used by the LoRaWAN® gateway

LoRaWAN® for agricultural IoT will be difficult unless weand so forth.

can achieve either of the following:

2.4.2 Simple Pre-installation Data Link Tests• Install inexpensive base stations outdoors

Even if you are able to install inexpensive base stations out-

• Easily assess data link performance before installation

doors, you may need to relocate them or add additional units
if you are unable to easily determine beforehand that they

To solve these issues, our aim was to make the system

can link to devices without any issues.

as DIY-friendly as possible for agricultural businesses. I describe our solutions below.

Several companies offer commercial wireless simulators that
let you enter base station latitude, longitude, and installation
height to simulate data links with peripheral devices. We

2.5.1 DIY Solar-powered Base Stations to Expand Installation
Options and Cut Installation Costs

actually tried one of these, but while the simulator included

If the TLG3901BLV2 indoor LoRaWAN® gateway included in

topographical data, it did not include data on buildings andMizukanri Pack S could be waterproofed and made to run

trees, so we were unable to determine the effect of suchon a cheap solar panel and battery, obviating the need for

objects on data links. When we compared the results of thea power supply, then it could be installed on the edge of

wireless simulator with real-world measurements taken in

paddy fields where it was previously not possible to do so

the vicinity of the paddy field water management IoT test

and thereby provide stable data links. So we decided to makesite, the simulation tended to match the real world in places

available a DIY solar-powered base station package that ag-

with few buildings, but even then, when testing close to

ricultural businesses can easily set up themselves, consistinga building, we found that small changes in device positionof a cheap solar panel and battery and materials readily avail-can greatly affect data transfer success rates. Even if data

able online or at home centers. Agricultural business owners

on buildings and trees is incorporated into the simulator inare used to DIY, with many building their own greenhouses

the future, covering all buildings and trees is likely to be

for instance, and they often have a decent set of tools, so we

difficult, as is keeping the data up to date, so disparities be-believe they will be able to install the DIY solution themselves

tween simulation and real-world testing seem inevitable. In

as long as we provide a clear set of instructions. Finding an

the real-world tests, the data links were also sometimes un-

installation spot along the side of a field should also be easy,stable near busy roads. Assessing such time-based changes

and the cheap price means that the system can easily bein data link status is also likely to be difficult in wirelessrestored if it is, say, damaged by natural events or stolen.

simulators, even in the future.
We expect the package we are putting together to proSo simulation-based pre-installation checks of connectivity

vide a solar-powered base station that runs year rounddo have their limitations, and you need to do real-world tests

at an additional cost of about 70,000 yen on top of theto say anything with certainty. However, there are limits to

TLG3901BLV2. To evaluate the package, we have alreadythe extent to which we, or a contractor, can measure con-obtained materials and built a DIY solar-powered base sta-

nectivity every time a base station or device is installed, andtion ourselves (Figure 5), and I blogged about the process.

this would also be costly.

See my posts for more details*2.

*2

IIJ Engineers Blog, “We set up a solar-powered LoRaWAN® base station for smart agriculture (Parts 1 & 2)” (https://eng-blog.iij.ad.jp/ archives/5567, in Japanese)(https://eng-blog.iij.ad.jp/archives/5599, in Japanese).

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2. Focused Research (1)Four of us installed the first solar-powered base station, but

2.The measurement process will take 5 minutes and con-

we believe we need to make improvements as we develop

sist of 30 individual measurements taken at 10-second

the package so that two people or fewer can install it in ashorter amount of time. So we recently arranged to use alocation relatively close to our workplace for a day, and undeterred by rain, ten of us tested out a number of installationintervals.
3.The wireless survey tool will have an LCD screen todisplay measurements in real time.
4.The TLG3901BLV2 will be usable without a SIM.

patterns using various tools and materials. I hope to write
the experience up in a blog post soon. And we look forward

We decided on Requirement 1 to make it easy to conduct

to launching a package that embodies what we learned.

testing anywhere. If we created a smartphone app, users
would need to learn how to operate it, but some agricul-

2.5.2 Simple Data Link Tests via a Wireless Survey Tooltural businesses are not all that familiar with smartphones.

To enable agricultural businesses to easily measure data

Mizukanri Pack S includes a smartphone app, so users needlink performance themselves, we decided to develop ato acquaint themselves with its use once they decide to

wireless survey tool, a device that measures data link per-install the system, but we wanted to make the bar as low

formance. We started out with the following development

as possible in the initial pre-installation survey stage. Making

requirements.

the devices battery powered not only eliminated the need tobe near a power source, it also made it possible to eschew

1.We will not create a smartphone testing app. The
system will consist of only the TLG3901BLV2 and aa power button and have tests start automatically when thebattery is connected.

wireless survey tool. Both will run on a mobile battery
or dry-cell battery.

Figure 5: DIY Solar-powered Base Station© Internet Initiative Japan Inc.

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Requirement 2 is in line with devices we have used for test-shows the number of successes over the total number ofing so far. Although the LoRaWAN® specification allows fortries (Figure 6). Displaying the test results in real time wasshorter intervals, we selected our interval in light of poten-

also a good idea because the user can disconnect the bat-tial interference in the case of multiple devices using thetery and stop the test if no data is being received at all.

same 920MHz band being nearby as well as the potentiallystrong effect of environmental noise from, for example,

Requirement 4 is there because otherwise, if we were to

moving vehicles.

create several sets of the TLG3901BLV2 and wireless survey tool to lend out to people, we would need the same

We decided on 3 instead of a smartphone app. The wirelessnumber of SIMs. As Figure 3 shows, LoRaWAN® systems

survey tool sends an ACK request via uplink to the Kiwi

normally need to connect to a network server in the cloudTechnology LoRaWAN® gateway. If an ACK is returned,

and thus need a mobile line accessed via a SIM or the like.

it is counted as a success; if no ACK is returned, this is

Fortunately, Kiwi Technology LoRaWAN® gateways fea-a failure. Successes and failures are displayed as 0 and X

ture their own built-in network server. Figure 7 illustrates aon screen. Once the data link test is complete, the screen

LoRaWAN® system using the built-in network server.
The built-in network server enables the gateway alone toprovide almost the same level of functionality as network
servers usually available in the cloud. The gateway can store
data received from devices in internal storage for a period,
allowing for its retrieval externally at any time via a REST
API. You can also request control of devices via the REST
API. When an ACK is received from a device, you can return
an ACK from the unit. This allows for bidirectional communication with devices even if the application server cannot
be reached. The built-in server was originally intended tofacilitate PoC in the absence of a network server contract,
but we were also able to make effective use of this featurein the wireless survey tool.
Figure 8 shows the prototype wireless survey tool that wedeveloped. We have actually already lent it to a number ofpeople to use, and in addition to the expected outcome ofusers being able to perform a preliminary survey of wirelessperformance, some also expressed surprise at the system’s
range: “It picks it up from this far away?!” So the tool also

Figure 6: The Wireless Survey Tool’s LCD Screen

The gateway has a built-in network server feature
DeviceGateway

Network server

Application
server

Application

Gateway

Network server

Application
server

Application

DeviceDeviceDeviceFigure 7: Overview of a LoRaWAN® System Using the Built-in Network Server

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2. Focused Research (1)turns out to be an effective way for people to experienceof the LoRaWAN® gateway by adding SACM zero-config

the long range LoRaWAN® offers before installing a system.

support, for instance.

It is also an effective way of collecting real-world test datafrom a whole range of locations, something we could not do

SACM is a next-generation management system service foralone, so we hope to continue utilizing the wireless survey

routers and IoT gateways, developed by IIJ based on SMF

tool while making additional improvements going forward.

technology, which enables the automatic connection andcentralized management of devices, and offered on an OEM

2.6 Conclusionbasis. With zero-config support, a device will automatically

We have discussed the features and suitable applications

connect to SACM when powered on, acquire its settings,

of LoRaWAN® compared with other LPWA wireless net-and start running. This eliminates any need to operate aworks and the advantages of LoRaWAN® in agricultural

device directly. The user interface allows SACM adminis-

IoT. We also looked at challenges to promoting the use of

trators to centrally configure, monitor, and manage a large

LoRaWAN® in agricultural IoT along with solutions.

number of devices. See our Focused Research report in IIR
Vol. 36 for details of SACM*3.

However, solving the issues we discussed merely means
we have done the minimum groundwork necessary to put

The features we have developed for agricultural IoT and the

Mizukanri Pack S on the market. If sales volumes rise, wesales and operating knowhow we have built will also be

will have to address issues including simplifying pre-ship-

effective in deploying LoRaWAN® solutions for other appli-

ment kitting and making it easy to diagnose the situation

cations. By continuing to develop this technology and buildwhen problems arise after a product is shipped. To that end,a knowledge base, IIJ aims to lower the bar to implementing

IIJ is working with Kiwi Technology to extend the features

LoRaWAN® and see it deployed in a range of different fields.

Figure 8: Wireless Survey Tool Prototype

Moto Onishi
Product Manager, New Business Promotion, IoT Business Division, IIJ
Mr. Onishi joined IIJ in June 2016. He handles project planning for IoT and camera solutions.

*3Internet Infrastructure Review (IIR) Vol.36 (https://www.iij.ad.jp/en/dev/iir/036.html).

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