Over the past year, there has been an outcry within the metering industry for standardized AMI. This effort is being pushed in the electric and water industries, with the hopes that buying one manufacturer’s system would not tie an organization down to that manufacturer’s meter, transmitter, or collector. While there is the possibility of opening the market, if a standard exists that everyone follows, where is the need for innovation and outside of the box thinking? Similarly, do the standards inhibit this innovation at a technical level as well? Certainly it can be argued that a standard can cause the technical approach to be stifled based on the restrictions of the approach itself.
During the IFAT conference in Munich, Germany I was exposed to the M-bus (Meter Bus) standard created for the purpose of standardizing a meter communications protocol. This protocol supports both wired and wireless specifications (more on wireless later) that define how a meter should communicate. M-bus was originally created to provide an easy means for retrieving readings for heating and cooling meters in an apartment complex. These radiator service meters are prevalent outside of the US market where central HVAC is not common. To simplify the reading of these meters, the wired M-bus standard calls for a gateway device that is wired in a circuit to each meter in the building; from there the gateway provides TCP/IP communication to any computer. The total baud rate for this circuit is 9.6 Kbps (that’s kilobits per second).
Wireless M-bus has since become an option. This allows for data transmission over the M-bus protocol through any wireless network. Obviously the options are greatly expanded and allow M-bus to utilize 802.11 and LORA, but you’re limited to a 115.2 Kbps baud with this version of the protocol. You must also use a wireless M-bus gateway that has no repeating capability as the standard calls for meter to collector to head end only. This means that no collector to collector and no meter to meter communication can be utilized to retrieve messages using M-bus protocol, according to the standard definitions.
Now let’s compare the M-bus protocol to a cellular AMI solution using CDMA 1x (or EV-DO). These solutions could potentially be at minimum 153.2 Kbps baud, but peak at over 3Mbps and allow for two way communications. To be fair, that is a cellular network managed by a for-profit company, so let’s compare to a solution utilizing the ISM band. The ISM band is the open license band between 902 and 928 MHz. Many US AMI vendors utilize this band for their networks. This band offers about 128Kbps on the low end and around 6Mbps on the upper end, but would be restricted by the vendor’s specific protocol, typically around 200 kbps baud. The third solution is a licensed network solution, which can offer around 16KBps (that’s bytes per second) baud on average; comparing that to the cellular solution, that comes out to about .128 of the cellular total data but still 13 kbps better than maximum bandwidth on the M-bus protocol. See image below.
So why does any of this matter? If M-bus can utilize LORA for wireless transmission, the network isn’t a major factor; rather the protocol is limiting the max transmission speed. Several manufacturers have moved back to licensed networks after utilizing ISM for many years; a couple have moved to LORA. If the manufacturer has the option to build a non-standard protocol within the confines of their own network, they are able to expand and innovate on that without issue. If a manufacturer is limited to one protocol with limitations to allow for homogenization, what opportunity is there for innovation?
In closing, I believe with the exception of adoption of TCP/IP (currently used in computer networks) as the protocol, standardization only limits what can be done on a metering network and slows the ability for a vendor to innovate if they have to report back to a consortium for a standard. While others want standardization, I believe it is better for all to allow non-standard competition.
Do you think the U.S. should standardize it’s AMI market?