Sub-GHz Communication System

We offer IoT communication systems using Sub-GHz (e.g. 920 MHz band) communication modules. The IoT communication system enables the customization of communication specifications for various applications and is able to configure a system that integrates with multiple sensors without contracting for communication services.

Sub-GHz Communication System Overview

The system sends data from sensors paired with Sub-GHz communication modules to the cloud via gateways.

Sensor -> Gateway in each area -> Cloud

Features

01 Unique communication protocol

SMK's original communication protocol uses the 920 MHz band. This communication protocol can customize the amount and rate of data transmission and develop software that is compatible with existing systems.

02 Communication range

With a transmission rate of 100 kbps, it is possible to communicate over a range of several tens to several hundreds of meters. An additional gateway allows data communication over even longer ranges.

03 Stable network connection

Radio waves have desirable diffraction properties and immunity to interference. This means that they bend around obstacles and are less likely to be affected by other radio waves.

Use Cases

Cart Location, Temperature and Humidity Control for Warehouses

The approximate locations of the carts and the temperature in a warehouse can be controlled by receiving data from the communication units via the gateway. Each communication unit has an embedded temperature and humidity sensor built into each cart to send data using the gateway's MAC address.

Store Refrigerator Temperature Control

The data collected by the temperature sensors inside the refrigerators or freezers that are made of metal or other materials can be sent periodically to the gateway outside these appliances.

Collective Control of Office Lighting

Collective control of office lighting, such as illuminance and on/off, is enabled by embedding a communication module in each luminaire.

Street Light/Street Lamp Failure Detection

Maintenance vehicles can collect abnormal signals from street lights or lamps with built-in communication modules via the individual vehicle gateway while driving.

Product Specifications

External dimensions WｘDｘH (mm)	13.0ｘ13.0ｘ2.3
Radio frequency	920.6 - 928.0MHz
Transmission rate	100kbps
Transmission power (Max.)	+13dBm
Receiver sensitivity (Typ.)	-85dBm＠PER1％
Interface	UART
Current consumption (Typ.)	Transmit mode:38mA Receive mode:25mA
Operating temperature	-30 to +85℃
Power supply voltage	1.8 to 3.6V
Antenna	Can be chosen from 90 or more different types of antennas.

What is Sub-GHz?

Sub-GHz is a unit of frequency and indicates frequencies below 1 GHz. In general, Sub-GHz bands are between 100 MHz and 1 GHz. Frequencies in this range are not susceptible to noise or other radio waves, and are used in various communications technologies and electronic devices.

	Sub-GHz Module （920MHz）	Bluetooth LE （2.4GHz）	Wi-Fi （2.4 / 5GHz）	LTE
Communication range	Positive (several hundred m)	Negative (10m)	Positive (several hundred m)	Positive (several dozens of km)
^*Radio wave diffraction	Positive	Negative	Negative	Positive
Amount of data transmission and reception	Small (several kB)	Large	Large	Large
Usage limits (including communication fees, registration fees, and other fees)	Positive (None)	Negative (Alliance certification is required.)	Negative (Alliance certification is required.)	Negative (A flat communication fee is required.)
Customization of communication specifications	Positive (Can be customized upon request.)	Negative (Must comply with specifications.)	Negative (Must comply with specifications.)	Negative (Must comply with specifications.)

*

Diffraction is the property of radio wave propagation that radio waves travel through space where there is no line of sight due to building corners or columns (see figure below).
When radio waves are sent from behind a building where there is no visibility, they will bend around the corners of the building to be received.