［ Basic Technologies ］

Development of Data
Communication Terminals
Applicable to Low Power WideArea (LPWA)
Keywords

IoT, LPWA, Low power consumption technology, Energy harvesting technology

Abstract

As a result of the recent proliferation of the Internet of Things (IoT) devices,various equipment and apparatus are connected to the Internet and a variety ofgathered data and information are exchanged. Part of the gathered data is information not formerly available or too difﬁcult to collect. As the result, new business opportunities are increasing with managing the analysis of suchinformation.
According to the type of monitoring tool and kind of information being gathered, these newly developed systems deal with different timing and volume ofdata gathering. In addition, the market calls for cheaper communication costs
and cost-effective data communication terminals that cost less in system installation and maintenance.
We realized a lower communication cost by adopting Long Term Evolution(LTE) and Low Power Wide Area (LPWA) communications conforming to relevant
communication standards. In so doing, we realized a long-term battery drive anddeveloped data communication terminals with minimum cost for the cablingwork.

1 Preface
In recent times, information actively utilized invarious maintenance work or services was formerly
acquired manually by people, not collected automatically with the use of machines. A businesscalled “sign diagnostic service” by which equipment
temperature, vibration, and operating conditions aremeasured, compares the acquired values with thedata of normal conditions and analyzes them toyield a ﬁnal judgment. Such technical trends areexpected to continue in the future. It is generally
believed that information can be accumulated frommany different directions and sources.
In order to acquire these data, measures taken
must be easily realized. Since a variety of objects
can be predicted for gathering data, the market calls
for the omission of construction work for a power
supply system and the elimination of cabling work.
In order to meet such market needs, we developed a data communication terminal that is a combination of an ultra-low power consumption micro-02

Hiroto Hideshima,
Toshiyuki Okitsu,
Masahiko Kudo,
Yuki Ota

MEIDEN REVIEW Series No.181 2021 No.1

computer technology and a Low Power WideArea (LPWA) communication system that realizes
long-distance communications with low power consumption. Fig. 1 shows an external appearance of
this terminal. This paper introduces the features ofour data communication terminal.

Fig. 1

Our Data Communication Terminal

Our data communication terminal is shown.

2 Low Power Consumption Type
Microcomputer

3 Low Power Consumption
Communications

Fig. 2 shows the outline of the monitoring system expected to be in demand in the future. For
microcomputers adopted for our embedded typecomputer systems, the market calls for features
such as high-speed processing and multiple functions.
These microcomputers tend to increase theirpower consumption. Practically, some hundreds ofmilliwatts (mW) is consumed. For this reason, it isindispensable to install a large-capacity battery cellfor extended computer operation under the conditions of no source of power. Such a feature is notsuitable for a data communication terminal. Unlike
technical achievements in the past, a low power
consumption microcomputer is based on a designconcept to lower the power consumption thoughother functions are limited. The adopted Central
Processing Unit (CPU) can lower the power consumption down to 10 mA during operation andapproximately 1μA in sleep mode. Using such alow power consumption microcomputer, we havedeveloped a data communication terminal that canbe used for an extended amount of time with minimal power consumption.

Data communication terminals released in thepast were based on the communication standard formobile phones. At an early stage, a communication
module conforming to the Code Division Multiple
Access (CDMA) Standard was adopted. Because ofrecent trend changes in mobile phone networks,
however, modules conforming to the Long Term
Evolution (LTE) Standard have been adopted.
Communication charges initially based on a datavolume charging system have been changed to ﬂatrates. Consequently, large-capacity and high-speed
communication has been realized assuring a
reduced communication cost.
In the case of communications through theInternet of Things (IoT) devices, however, there is
not always the necessity for securing large capacity
and high speed performance according to the information gathering device. Instead, lower power consumption and lower communication costs may be
more important. As such, we have adopted theLPWA communication system featuring low power
consumption, low bit rate, and a wide-area coverage. When the LPWA system is adopted, power
consumption during communication can be reduced
to 1/3 compared with conventional LTE and to 1/100
or lower during waiting period for some modes.
There are multiple communication standards
deﬁned to correspond to LPWA. Our data communication terminal is capable of accommodating communication modules belonging to various communication systems that conform to LoRa, SIGFOX andCat-M1.

Demanded monitoring
systemVisualization ofinformation
Omission of power
supply and battery
Anytime andanywhere・High speed・Multiple functions
Power consumption:
Hundreds of mW
Present built-in typecomputer system

3.1 Communication Standard “LoRa”

Various data
gathering
Automation andlabor saving
Installation without
construction work
Simplified
maintenanceFig. 2・Low power
consumption
・Reduced to necessary functions only
Power consumption:
Hundreds of μW
Built-in type computer systemapplied with low power
consumption techniques

Outline of Monitoring System Expected to be in
Demand in the Future

The outline of the monitoring system demanded to realize an IoTsociety and the application to our built-in type computer systems
are shown. Since a conventional built-in type computer system
consumes very much electric power, it is not suitable for use in
the IoT-based monitoring system.

This is a communication system utilizing communication bands that donʼt need any license. A
nonproﬁt organization by the name of LoRa Allianceis promoting the activities for spreading this standard. The communication rate is some tens of kbps
and the perspective communication distance isbelieved to be around 15km at the maximum.

3.2 Communication Standard “SIGFOX”
As for LoRa, this standard similarly does not
require any license and is managed by SIGFOX Inc.
in France. A featuring characteristic is that communication is repeated three times with different frequencies. The communication rate is 100bps andMEIDEN REVIEW Series No.181 2021 No.103

the communication distance is said to be around50km at the maximum.

3.3 Communication Standard “Cat-M1”
This system uses a frequency band that
requires a license. It is standardized by the 3rdGeneration Partnership Project (3GPP) that is astandardization unit of communication systems formobile phones. In Japan, services are offered byKDDI Corporation and other organizations. Thecommunication rate is said to secure 1 Mbps andthe communication distance is around several kilometers. This system is rich in the power-saving
property by providing a sleep function in the communication module. Compared with versions ofother standards, in many cases, communication
cost is lower.

4 Development Concept for Data
Communication Terminal
Fig. 3 shows the development concept. In
order to reduce power consumption, power saving
parts inclusive of microcomputer are adopted. Inaddition, power consumption is reduced by a function that produces a sleep mode while the device isout of service. Table 1 shows speciﬁcations of thedata communication terminal. In order to make thisterminal applicable as a data communication termiUltra-low power consumption
type microcomputer

nal, it is provided with a Digital Input (DI) circuit,
Digital Output (DO) circuit, and an Analog Input (AI)circuit so that various kinds of sensors can be connected. Since the data communication terminal isprimarily assumed to permit intermittent operation,a periodic startup operation is carried out with theaid of a built-in calendar Integrated Circuit (IC). In
addition, there is a function to enable the starting ofa microcomputer at the time of a status change inthe DI and variations in analog values of the AI.
As a means of transferring the gathered information, a wireless communication function is accommodated. On the assumption that operation is conducted with a power supply of the primary battery,
the working period of several years with a built-in
primary battery cell is realized, though this depends
on the period of intermittent operation. For software,
the T-Kernel of the built-in type real-time OS isadopted.

Table 1 Specifications of Data Communication Terminal
Speciﬁcations of our data communication terminal are shown.
ItemCPUBattery cellWireless/wiredSpecifications

CPU

32 bit RISC 48 MHz

Built-in flash
memory1024 KB

Built-in SRAM

128 KB

SRAM512 KB

FRAM256 KB

A/D converter

12 bit 8 ch

Cat-M1 communications

Cat-M1 communication module

Specific lowLoRaWAN communication module,
power wireless SIGFOX communication module

or storage
battery
Wireless technology

Serial port for
maintenanceLight

Monitoring AI
and control

Heat
Charging
deviceDI・DO・AI

Vibration

Various sensors
Energy Harvesting Technology

Fig. 3Development Concept for Data Communication
Terminal

A development concept for a data communication terminal developed by us is shown. In order to enable application to a monitoring system demanded by an IoT society, ultra-low power consumption type microcomputer and low power consuming devices
are adopted. By making intermittent operation, system operation
is made possible only with a primary battery. As a measure taken
to eliminate a power supply, energy saving technology is utilized
to make it possible to charge up the secondary battery (storagebattery).

04

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PrimarysourceOS

4 ch (0〜5 V or 4〜12 mA),
Source voltage monitoring

DI8 chDO

4 chI2C

1 chPower source circuit
EnergyharvestingsourceCPU built-in UART

3.3 VA・3.3 VB・3.65 V・24 V

Thermal power 30〜500 mVgeneration
Vibration
2.6〜23 V
power generation
Photovoltaicgeneration

0.3〜4.75 V, 2.6〜23 V

Secondarybattery

Various lithium batteries

14.4 V, 5 V

Lithium battery 3.6 V, 4-serialpack
T-Kernel2.0

5 Energy Harvesting Technology

6 Postscript

The “Energy Harvesting Technology” is a technique to “collect” minute energy in a variety ofmodes available in the surrounding environment,and convert the collected energy into electric power.
Since the electric power obtained from this expertise is substantially feeble, this method is not suitable for actuating large equipment. It is, however,possible to utilize this power for equipment that isdesigned to realize reduced power consumption. If
this method is realized, no cost is required for power
generation and cabling for power supply can beomitted. As a result, the degree of freedom isincreased in terms of equipment installations. For
our data communication terminals also, we havedevised a power source conﬁguration by whichenergy (of light, heat, and vibration) scattered in thesurrounding environment is selected and converted
into electric power to charge up the secondary battery for use.

Data communication equipment of the low
power consumption type is considered an indispensable tool in an IoT society in the future and various kinds of developments are anticipated to arise
accordingly.
While our applications are promoted to thesystems of reduced power consumption and energy
harvesting technologies, we will continue to promote the development of products by incorporating
new technologies meeting the needs of industrialmarkets.
・LoRa is the trademark of Semtech Corporation.
・SIGFOX is the trademark of SIGFOX S.A.
・All product and company names mentioned in this paper are
the trademarks and/or service marks of their respective owners.

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