By Todd Ellis
Like all providers in the Southwest, the Albuquerque Bernalillo County Water Utility Authority is constantly looking for new ways to balance source supply with costs.
To gauge how and when people use water and how much the authority's losing to leaky pipes, managers began upgrading their automated meter reading (AMR) system to advanced metering infrastructure (AMI). Having deployed one-way communication to lower the potential for inaccurate readings due to simple human error, they've moved to the next step: using two-way communication to develop time-of-use pricing programs and other peak shifting programs.
They began with commercial customers, which represent 13% of demand and provide 20% of revenue, replacing 850 meters with radio-equipped iPearl meters. In January, they began rolling out the program to 200,000 residential customers. The communications network is called FlexNet, provided by Sensus, an open-source protocol that provides fixed-base (meaning the equipment's permanently installed) remote meter reading.
Mesh: Groups of meters communicate to each other before communicating with a transmitter that signals back to a base station.
Point/multipoint: Meters individually transmit to base station.
“The business case was clear,” says Policy Manager Frank Roth. “Two-way communications increases meter reading accuracy, improves service, reduces data collection costs, and quickly gathers critical information that provides insight to utility decision-makers.”Two communications options
Although the two types of radio-based communications technology differ in architecture and signal type, both are used for AMR, AMI, distribution automation (DA), and supervisory control and data acquisition (SCADA):
- Privately licensed spectrum signals carried over a point-to-multipoint network architecture (for definitions, see box on this page)
- Publicly available spectrum signals carried over a mesh network architecture.
Most utilities don't combine the two approaches, but it's one way to accommodate service area geography. For example, a small metering mesh network in a rural setting may connect to an urban point-multipoint communications network to send data to a centralized control center, or base station, in a process known as “back haul.”
Both approaches are based on American National Standards Institute open standards (C12 for smart metering and X9.112-2009 for wireless management and security) and can be scaled to grow — extremely important considerations for maximizing return on investment. The standards ensure asset interoperability, while the scalability allows you to test out a system and stop there or continue building out. To select a network that fits current and future community and budget needs and delivers equal or improved reliability, also avoid equipment and networks that:
- Require all-proprietary communications
- Lack interoperability with other vendor solutions.
Mesh and point-to-multipoint are the two distinct architectural approaches to two-way radio communication networks. In a mesh network, many radios (also referred to as endpoints) talk to each other, peer-to-peer. Each point on the network can receive, store, and transmit signals to other points in many directions. In a point-to-multi-point network, there is a “master/slave” relationship in which a single point can talk to all the other points individually and they can talk back to it — but not to each other.
Signal transmission characteristics
All mesh networks use unlicensed spectrum for their communications channel. They operate on public, not private, channels. Often referred to as the industrial, scientific, and medical (ISM) frequency band, this spectrum is shared with a wide range of devices including cordless telephones, baby monitors, and wireless Internet access modems.
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Like the IRS, technology makes it difficult to exploit loopholes. Private radio spectrum offers greater privacy, security, range, signal-to-noise ratio, and latency — but all those benefits require a higher upfront investment.
Public spectrum is free and, when more than one wireless provider serves a geographic area, redundant — but its limited range requires buying and installing more equipment to make the system work.