World's first Small-sized, Low-power “Smart Meter Radio Device” compliant with IEEE 802.15.4g/4e standards for Japan’s new 920 MHz band allocation

Recently, reducing excessive energy consumption by controlling meters of electricity, gas and water in homes and buildings has been of great importance to environmentally-friendly technologies. NICT has conducted research and development on the smart meter system with radio communication technologies that effectively and surely realizes automatic and autonomous control, data reading and monitoring on each meter. Such NICT’s efforts have been reflected on standardization activities in IEEE 802 committee and been successfully adopted in IEEE 802.15.4g/4e drafts.

In Japan, “950 MHz band” allocation for RFID system was originally considered to be suitable for the allocation of smart meter utilities. However, MIC (Ministry of Internal affairs and Communications, Japan) officially announced “920 MHz band” allocation for smart meter usage in Jan. 2012 for the benefit of the international cooperation and competitiveness. Accordingly, NICT, domestic users and manufacturer companies have submitted a unified proposal for clear and effective 920 MHz utilization to IEEE 802.15.4g/4e task groups. As a result, those task groups have finalized IEEE 802.15.4g/4e drafts (to be finalized as standards in Mar. 2012) defining such “920 MHz band” allocation. Although significance of standardization and realization of the smart meter system is confirmed with the establishment of "Wi-SUN alliance" in Jan. 2012, any radio device compliant to such finalized IEEE 802.15.4g/4e standards has not been developed yet.

The standardization in IEEE 802 committee is to be completed in Mar. 2012. NICT is going to create a safe and relieved society by ICT, with the standardization basements by way of Wi-SUN alliance. NICT is also seeking an opportunity of this device’s technology transfer.

Fig. 1 shows a system image of SUN.

In Fig. 1(a), a radio device equipping gas/ electricity/ water meter is allocated to each home and transmits the timely data read on the meter. Such meter data are collected to the collection/ control station in a SUN service area that is equivalent to an apartment building or a portion of residential area with several houses. As in the figure, multi-hop transmission among radio devices guarantees the required communication range and eliminates radio blind spots caused by obstacles. The collected data by SUN can be relayed in the wide area networks (WAN) and further collected in the collection/ control station in the WAN.

On the other hand, Fig. 1(b) shows an application image where the smart meters as dosimeters or climate sensors have conducted monitored data collection by exploiting radio links among meters. In this case, multi-hop transmission capability is effectively utilized in order to conduct operations of distributed meters in multi-point, and low-power performance capability enables continuous and long-term monitoring.

Fig. 2 shows the developed radio device for the smart meter and Table 1 shows its specifications.

Fig. 3 shows a concept of access control employed in the developed radio device. The beacon signal is usually turned off in order to avoid excessive power consumption owing to periodical transmission and it is transmitted only when requested. There are two types of periods; the active period and the sleep period as in Fig. 3. Only the active period includes receiving or standing by state of the device. In contrast, the sleep period indicates sleeping state of the device except for the case the device continuously receive a data frame from the last active period as in Fig. 3, which can decrease the average power consumption by exploiting the existence of sleep period. The developed radio device automatically and autonomously constructs a tree topology as in Fig. 3 after turned-on, then conducts an effective collection of data relaying as depicted in Fig. 3.

IEEE 802 committee is a committee engaged in standardization for communication systems such as LAN in IEEE (Institute of Electrical and Electronic Engineers) that is a non-profit professional association dedicated to advancing technological innovation related to electricity. In the committee, a working group (WG) named IEEE 802.15 deals with the standardization for wireless personal area networks (WPAN). This WG accommodates several task groups (TGs) as depicted below, each of which is organized according to its goal.

• IEEE 802 committee web site: http://www.ieee802.org/
• IEEE 802.15WG web site including anchors to other related TGs: http://www.ieee802.org/15/

PHY (PHYsical) layer means a concept that expresses subdivided communication functions by assuming hieratical layers as well as MAC layer. PHY layer defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a transmission medium, such as a copper or optical cable and connector types for the cables.

MAC (Medium Access Control) layer means a concept that expresses subdivided communication functions by assuming hieratical layers as well as PHY layer. MAC layer provides addressing and channel access control that enable several terminals or network nodes to communicate within a multi-point network, which is represented by the MAC addresses peculiar to communication devices or by the time divided access scheme; TDMA.

A certification for a radio device referred in "Enforcement Ordinance of the Radio Law" by MIC, which certifies the device to conform to the technical standards regulated by Radio Law. With this certification, a radio device can be practically used in every region of Japan.

An organization that supports certification and promotion for smart meter radio communications by assuming IEEE 802.15.4g standards adoption for low-power smart meter radio systems. Wi-SUN alliance is established on Jan. 24th, 2012. NICT is a promoter member of Wi-SUN alliance.

Please refer to the press release below:

Multi-hop transmission means a transmission that includes more than one relaying by other radio device(s) than transmitter and receiver devices, which is different from the direct transmission between devices. The reachable range of the multi-hop transmission can be proportionally expanded to the number of relaying. Moreover, the multi-hop transmission enables the same reachable range as a direct transmission with lower transmission power for each device than that for the direct transmission. Furthermore, the multi-hop transmission can also provide relaying route avoiding obstacles for radio waves thereby eliminates radio blind spots.