TOKYO GAS TOP > Technical development > Smart society > Development of a gas smart meter system

Development of a gas smart meter system

Tokyo Gas is developing gas smart meter systems comprising U-Bus equipped Ultrasonic Meters, wide-area wireless networks, U-Bus Air networks, and center systems.
Eight other companies collaborated with Tokyo Gas to evaluate technical specifications, creating industry standards within Japan. Work is also being done to standardize internationally through measures such as proposing IEEE802.15.4-2015 as a communications specification for U-Bus Air and incorporating this proposal in a planning document.
 

Purpose


Tokyo Gas performs meter reading once a month in order to calculate gas rates. Once a month, meter readers visit customers’ homes to read the indication values on their gas meters in order to confirm the amount of gas they have used. 
However, carrying out such home visits is becoming increasingly challenging due to such factors as self-locking apartment buildings and other increased home security measures, as well as projected challenges like how to ensure meter reading is performed more efficiently and thoroughly in the face of a declining population which will mean a shortage of meter readers. These and other factors are driving a growing need for remote meter reading performed via smart meters. Also, the introduction of smart meters is expected to contribute to greater pipeline network safety and disaster resilience through the use of remote shut-off functionality, as well as foster the creation of new energy efficiency services and services which use remotely obtained gas usage data to help relatives and caregivers of elderly residents keep track of their daily wellbeing.
 
Gas smart meter systems contiguration image
Gas smart meter systems contiguration image
U-Bus-equipped Gas Meters, wide-area wireless, U-Bus Air networks, and center systems
 

U-Bus


U-Bus is a new communications interface that utilizes a packet transmission method with a higher transmission speed than the existing city gas meter transmission specification (A line). Tokyo Gas has evaluated specifications together with LP Gas businesses, and is standardizing these specifications, along with the U-Bus Air (detailed below), with the NPO  Japan Utility Telemetering Association (JUTA). Information on the U-Bus next-generation gas meter for residential use is listed here: This gas meter is being developed in conjunction with U-Bus communications terminal devices.
 
U-Bus specification
Layer Main specifications Characteristics
Physical
layer
Bus connection method
  • Shared use with devices of different kinds possible
Increased baud rate (9,600bps)
  • High speed transmission (30x faster than currently in use) allows for use in a wider variety of fields, and improves service levels.
Data link
layer
Packet transmission
  • Improved intercommunication with terminals with different baud rates
  • Improved line use efficiency
  • Improved resistance to damage
Fixed packet length (104characters/packet)
  • Improved processing efficiency of terminal devices
  • Improved responsiveness
    (1packet:0.12seconds)
Network
layer
Meter gateway function
  • Implementation of addressing that is compatible with wide area and relay wireless networks
Easy addressing
  • Less restriction on construction when installing terminals
Security Use of standard encryption
  • Improved authorization and confidentiality

 
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Wide Area Network gateway


The Wide Area Network gateway is a terminal fitted with a U-bus communications interface which connects customers’ home smart meters with Tokyo Gas’ central system via an LTE network.
 
System configuration image
System configuration image


 

U-Bus Air


U-Bus Air is a short-distance wireless radio communication system with extremely low power consumption which utilizes the 920 MHz band to provide relays between gas meters via multi-hop transmission. U-Bus Air utilizes the IEEE802.15.4-2015  standard and is used in accordance with standard NPO  Japan Utility Telemetering Association (JUTA) specifications. U-Bus Air devices are able to operate for 10 years on battery power, and can connect to meters outside the area of wide-area wireless coverage.  
 
U-Bus Air specification summary 
Frequency 920MHz band(ARIB STD-T108 standard)
Output 20mW、10mW、1mW
Baud rate 100kbps
Network topology Mesh. 50 units per network
Multistage 5 stages on average, with a maximum of 15 stages

 
U-Bus Air terminal characteristics
U-Bus Air terminal characteristics

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