The Best Networks & Technologies for Advanced Metering Infrastructure
AMI, Advanced Metering Infrastructure, has been a hot topic in the utility industry since the late 2000’s. AMI is defined as an integrated system of smart meters, communications networks, and data management systems that enables two-way communication between utilities and customers.
The Drivers of AMI
Although AMI can be used in Water, Gas, and Electric Metering, it is typically associated with Electric Metering. A primary driver for AMI was the economic stimulus package during the 2008 Obama administration to incentivize investment in the electric smart grid. Another major economic driver was the 2011 Fukushima disaster in Japan, which greatly reduced the electric power generation capability and increased the need for efficient distribution and consumption of energy in that country. Since that time, AMI has proven itself and has been adopted as mainstream by utility industries in both developed and emerging markets.
AMI communications networks are driven by the need for low-cost, low-bandwidth, delay-insensitive metering. It is important that both the network and the communications module in each meter be as low cost as possible. The early days of AMI saw narrow-band Power-Line-Communication (PLC) and RF-Mesh as the primary communication technologies driving the adoption of AMI. As Communication technology has advanced, newer technologies, such as Broadband PLC and Low-Power-Wide-Area networks (LPWAN), have become more the trend.
In PLC, the electric utility uses their own power lines to connect the meters (usually on the order of 10-1000 meter) to a concentrator. The concentrator is then connected to the utilities cloud data center with 3G, 4G, or fiber optic backhaul. Huawei’s AR530 is a good example of a concentrator for PLC type communications.
Because electric utilities can “own” the network of power lines connecting meters to concentrators, this is the typical preference. Since water meters and gas meters do not have power lines coming in to the meter, PLC is not an option for water metering or gas metering. In many cases PLC is not practical due to excessive noise on the power lines, or excessive signal loss over long reaches between the meter and concentrator. (Remember the power lines were made for transmitting power, not signals!) In other cases, even if PLC is technically workable, it may not be the lowest cost choice, due to the low density of meters per concentrator.
There are many “flavors” of PLC. Huawei supports PLC-IoT (standardized as IEEE1901.1) which is primarily used in China. Other major versions of PLC are G3-PLC and PRIME-PLC. The chart below shows a comparison trade-off. From a purely technical standpoint, PLC-IoT is superior to G3-PLC and PRIME-PLC. However powerful industry players promote G3 and PRIME, and their ecosystems are much larger and more international, so currently they both hold powerful positions in the market outside of China (especially G3-PLC).
In addition to PLC-type communication, there is also wireless communication for AMI. The wireless type is used in water, gas, and electricity metering. In water metering, an earlier “one-way” type of communication was called “Automatic Meter Reading” (AMR). In AMR the meter reader could walk-by or drive-by the meter location usually on a monthly basis, and uplink the meter consumption data. This would be stored on a local collection device (usually a laptop) and then uploaded to the utility cloud data center off-line at a later time.
Mesh & Star
In wireless communications for AMI, RF-Mesh, and Star topology are the two main choices. RF-Mesh usually works in the 920 MHz unlicensed ISM band and is deployed by the utility as an in-house network. ISM band is stands for “Industry Science Medicine” and is unlicensed. Unlicensed is “free”, but there can also be other users which cause unpredictable interference. Also there is a very low transmit power limitation: 1 Watt in North America (30 dBM), down to .010 Watt (10dBM) in Japan. In RF-mesh there are many proprietary standards usually controlled by the larger metering companies such as Landis+Gyr or Itron. There are also several standardized versions the main one which is Wi-SUN (deployed in Japan). Due to being promoted by the two largest metering companies and thanks to rich deployment use cases in USA and Japan, RF-Mesh is a very popular solution for electric utility.
Another wireless choice is star topology. Star Topology can include Cellular IoT (GPRS, 3G, NB-IoT, and LTE-M) as well as proprietary solutions like LoRA. For Cellular IoT, NB-IoT is the optimal choice due to low cost of NB-IoT networks and low-cost of NB-IoT enabled meters. Since meters are typically deployed for long periods of time (ten years is normal) operators want to avoid encumbering 10 year service contracts on GPRS networks that may soon be retired. 3G has a similar issue and many more expensive network and terminal costs than NB-IoT. For electric metering, LTE-M is another valid choice in addition to NB-IoT. The choice between NB-IoT and LTE-M is one of connectivity vs bandwidth. Typical electric meters for residential purpose send about 5-10 KB per day, with update intervals of between 15 minutes and 4 hours. Commercial and Industrial meters (C&I) have update intervals of between 1 and 15 minutes, and may send 50-100 KB information per day. NB-IoT is preferred for water and gas metering, and both NB-IoT and LTE-M are used for electric metering.
The Case for NB-IoT
LoRA was a LPWAN network designed and deployed mostly in the 2010-2016 period before the advent of NB-IoT in 2016. Since 2016, in most carrier markets (with the notable exception of Orange and KPN), NB-IoT has replaced LoRA as the LPWAN of choice. This is due to much larger ecosystem of devices and much easier deployment and management of NB-IoT by carriers using their existing base station hardware with only software upgrade required. LoRA uses the unlicensed ISM band so suffers from limited transmit power and unpredictable interference from other unlicensed users.
In summary, AMI networks for water, gas, and especially electric utilities offer a huge growth market for communication systems providers, especially carriers, with NB-IoT. Huawei has developed a leading ecosystem of water meter, gas meter, and electric meter partners for NB-IoT (and also PLC-IoT for electric meters). AMI is (arguably) the largest B2B use case for carriers to deploy to very large utility customers. On a smaller scale, AMI can also be deployed to large property owners for managing tenants’ electricity, water, and gas usage.