DMR Tier III for Internet of Things Applications
28 Sep. 2016 Information
DMR Tier III is making headway with utilities. However, it faces competition from other wireless technologies. Vaughan O’Grady investigates whether its combination of voice capacity, resilience, coverage and IoT applications could be a winning hand.
Wireless technologies have long played a part in the work of UK utilities – some of it via staff using public cellular networks on their smartphones and tablets. However, where mission-critical voice communications are involved private two-way radio
(most commonly the analogue MPT1327 system) has often been UK utilities’ method of choice. But both wireless communication and the utilities it serves are changing.
As Adrian Grilli, managing director of the Joint Radio Company, an industry-owned spectrum management consultancy and spectrum management organisation, explains: “At the moment it’s the old MPT1327; that’s the critical voice communications network we use.” But he adds: “You wouldn’t put in a new analogue system now that there is a digital alternative. DMR Tier III is mature, effectively doubles the capacity that you get in the band, and holds out the opportunity of more data and duplex voice.”
Data capability also potentially makes DMR Tier III useful for Internet of Things (IoT) applications. However, only Simoco Group and Tait Communications have a sizeable DMR Tier III utility customer base in the UK at the moment.
In any case, both agree that voice is still the mission-critical need. Mike Norfield, CEO of TTG (Simoco Group’s parent company), points out: “Whether it’s water, gas or electricity, they need to have voice communications first. It’s nice to say ‘I’ve got broadband’ but when an electricity network goes down the only way to get it up and running is communicating directly via a mission-critical network such as DMR.”
DMR so far
In isolated areas where DMR can deliver better coverage than cellular voice is especially important. “The safety-critical use [for voice] is to be able to do repairs and report problems,” says Grilli. “If you’re in the Lake District and the power goes down a guy will go out there and use two-way radio. He can report he’s on- site and what the problem is, give an update of how long it’s likely to take to repair and whether he needs extra equipment. Then, when it’s all repaired, he will speak to the control room to request reconnection or to get permission to re-energise the circuits. Finally, he can tell the control room that the circuit is now live.”
A higher capacity potentially duplex DMR Tier III offering could in theory be justified on this basis alone, but utilities have other needs – tracking workers on big sites as part of safety and security efforts, for example. Thames Water’s Walton treatment works uses location monitoring solution CALM+ from Chatterbox – a supplier of bespoke integrated two-way radio systems. CALM+ is a good example not only of health and safety applications, but also of changing utility approaches to communications technology.
It replaces an unwieldy amalgam of analogue radios, cellular devices and pagers with one compact, robust, two-way DMR-based radio
that supports voice, text and GPS (with a little help from Bluetooth beacons in internal areas where GPS may not be effective).
And it’s already evolving. “We have now provided CALM+ systems to the other three clean water sites in the Thames west London region; Hampton, Kempton and Ashford,” says Chatterbox MD Gary Leatherby. “The customer is currently upgrading its SCADA system and we have written new software so that our system integrates with it. We are now quoting for CALM+ systems for other regions within the clean water division, and have started discussions on how the customer might wish to integrate CALM+ within the sewage division. Each deployment is roughly the same, but with slight variations to work with the customer’s operational requirements at each site.”
But it’s in much larger areas where DMR will probably come into its own. Like its analogue predecessor it’s a low-band technology, so coverage is good. Norfield says: “Simoco’s Pulse DMR telemetry solution, which is being rolled-out in Western Power Distribution’s central region, will involve more than 100 sites moving to DMR. This will be followed by 116 sites in southwest England. It will give us 100 per cent coverage in these areas, which you don’t get from cellular.” And this is a private, fully redundant network so capacity issues and power outages aren’t a worry. Battery backups will last at least 48 hours, or longer with generators.
DMR and data
DMR Tier III’s data offering is more than just a useful extra. Guaranteed data is the second most important requirement for utilities after voice. “They need to know where on the network a fault actually is,” explains Norfield. “And that’s where they need telemetry and low-band data.”
This is partly why DMR’s reach and data capability are seen as useful in enabling wireless M2M/IoT applications – to report faults and monitor equipment.
Norfield says: “We developed Simoco Pulse, which allows you to put all of your telemetry – all of your SCADA [supervisory control and data acquisition] data – over your DMR network. It’s the most cost-effective way of doing that and the most efficient: you’ve got better coverage and all your technology in one network. At the moment a lot of utility companies are using three, four or five different technologies to get their SCADA data back to control rooms.”
A mix of cellular, unlicensed radio, PMR, microwave and/or Wi-Fi can thus be replaced by a DMR network. “The way we’ve been able to do that is not just to design the RTU [remote terminal unit], but to design how the infrastructure works to actually cope with tens of thousands of devices,” adds Norfield. The Western Power Distribution network will grow to about 250 sites covering a vast area, with some 30,000 RTU devices on that network. “It gives them the ability to have all that technology running on one efficient, cost-effective network.”
Jamie Bishop, marketing director EMEA at Tait Communications, is also interested in the IoT potential of DMR. His company serves utilities with voice and workforce management solutions. “From our perspective the biggest growth area is the IoT space,” says Bishop. “We have a solution called GridLink that enables automation of the electricity grid at the medium voltage level – 11kV up to around 24kV. It allows the grid operator to have real-time sensoring but command and control over the assets in that grid as well.”
He continues: “The grid was designed in the early 1900s to have large centralised generation and to press electricity out. Now you have inputs [wind, solar, nuclear, coal, tidal] all over the place. The grid once went from high voltage transmission lines into a distribution grid. Now there’s lots of input into low voltage or medium voltage parts of the grid. That changes the demand in terms of monitoring and necessitates an ability to control the grid on a real-time basis. Which is where, in some cases, DMR Tier III and other licensed radio technologies are coming in.”
DMR Tier III-based monitoring could help with restoring a network quickly when it goes down or predicting outages – useful when downtime means fines and regulatory compliance metrics have to be met. Institute of Electrical and Electronics Engineers reliability indices SAIDI (System Average Interruption Duration Index), CAIDI (Customer Average Interruption Duration Index), and SAIFI (System Average Interruption Frequency Index) are just three of these.
Monitor and maintain
The IoT enables power network owners “to do things like measure temperatures, variations in voltage, and different factors of devices deployed on the network so you can do predictive maintenance,” says Bishop. “Gridlink enables you to increase the coverage of your wide area network IT operations: to see devices normally unreachable from an IP connection perspective that can now be monitored in real time using SNMP [simple network management protocol].”
He adds: “You’re probably looking at 15,000 to 25,000 points that that kind of utility needs to monitor at this level.” The Tait solution “has all of the advantages of the DMR Tier III network in terms of resilience and redundancy, but it also now caters for mission-critical IoT data provision”.
And this is well within DMR’s capabilities. “When you tell me that DMR data rate is about 2.4 kbits per second that’s adequate for knowing whether your supply is on or off, transformers are on or off, the switch positions at those transformers and voltage, current and temperature. We don’t need high data rates to know about this,” Grilli points out.
However, DMR has competition in the IoT space. But the lack of standardisation among low power wireless IoT options could be to its advantage. As Grilli says: “There are a plethora of different technologies out there – all the low power ones: LoRa, ZigBee, Sigfox, Weightless, Nuel. A user thinks ‘what if I put 10,000 sensors out there and that technology fails?’ There is that risk.”
He also suggests that these technologies would usually have different uses from DMR; in what he calls “low-critical IoT-type applications” such as rubbish bins or vending machines that signal being full or empty. “With DMR you’ve got control, so if a device tells me it’s off supply or a switch has tripped I can command that switch to close; [DMR is about] control as well as monitoring.”
DMR is also standardised, operates in licensed spectrum, and is powered by the network (rather than batteries). “For DMR equipment in licensed spectrum you have protection from interference. You can use higher powers because it’s licensed spectrum, and then you’re looking at guaranteed longer ranges.”
DMR’s competition is most likely to be from GPRS, cellular IoT and narrowband LTE, he suggests, although when any technology is on a public network then there’s no fallback when the network goes down. Also having DMR voice and data on the same network is useful and “remote and rural areas are not a problem for VHF”.
Nevertheless broadband LTE is attracting interest although, as Grilli says, if voice and low band telemetry can protect a power network why do we need LTE? “If I know what comes in and what comes out of a water pipe then I can work out if it’s leaking or not. Why do I want a video feed? It doesn’t tell me anything useful,” he adds.
Surely sending and streaming video, pictures or even a whole manual from one site to another is a ‘nice to have’? It is, Norfield agrees, but “if you wanted to put an LTE network in to cover the Western Power Distribution area for instance, it would be somewhere in the region of about 40 times the cost. You’re basically building your own cellular network. 4G is also quite power-hungry. And you still won’t have the coverage using LTE at 450 MHz that you would using just DMR.”
And in the real world, Grilli points out, when 450 MHz to 470 MHz networks ask for a price list for LTE there isn’t one. “No price list and no multiple suppliers. So if you’re rolling out a smart metering network today LTE in the 450 MHz band is not an option. CDMA 450 is.”
Part of the reason this is the case is that the use of LTE in the UHF2 band (450 MHz to 470 MHz) is “not feasible because of other sectors such as emergency services, business radio, PMSE, maritime, and scanning telemetry making extensive use of UHF2 spectrum on a narrowband basis,” according to Ofcom. However, as part of its UHF Strategic Review it is investigating “whether re-farming of UHF2 would permit sufficient spectrum to be released to accommodate a LTE channel, but there is also the consideration of the impact on adjacent narrowband use.” Ofcom is also exploring scenarios for the use of LTE in UHF at the European level as part of CEPT Working Group FM54, which is currently at the information-gathering stage.
Grilli does, however, suggest one useful application for private LTE. “One of the things we’re looking at is tunnels; quite a lot of electricity cables in urban areas now run in tunnels. And having your own private LTE means you can run it in tunnels where you will never get a public LTE service.”