Continuing evolution of SCADA

In October 2023, I wrote about what future SCADA systems should look like and some of their requirements. Not surprisingly, the largest  was data management, including multiple types from multiple sources. Last year, I described how SCADA makes connections to get data to the right place and the right time. This time, the conversation is about how the backhaul network connects geographically distributed nodes to a central control room, and distributes their data to run facilities more safely, efficiently and securely.

My first exposure to SCADA was  supporting oil and gas production facilities in Alberta, Canada. They relied on private radios and plain, old telephone (POT) lines to connect individual wells to their treatment facility and back to the head office. Private radio is still used today, though in some cases it’s a collection of private, 5G networks. 

However, not all of Canada has cellular coverage, especially in the arctic. I worked on a project about 10 years ago to provide SCADA to communities in Nunavut, which is along the Arctic Ocean, from 105°  west latitude to a central control facility in a community at 68° west. They shared an uplink with the hamlet over the only connection to the rest of the world via a geostationary, Earth-orbit (GEO) satellite. Interestingly, a few years ago we were asked to integrate another community into this same system. It was in Hudson Bay, below the Arctic Circle and a little further south, but we were no longer talking about GEO. During those few years, low-Earth orbit (LEO) satellites shifted the landscape of satellite connectivity and now provide coverage with more bandwidth and lower latency than previously possible. 

You can imagine the bandwidth and latency challenges we faced with the original GEO solution. Fortunately, these projects only require remote monitoring and reporting, with local controllers responsible for real-time responses, and setpoint changes made infrequently by local operators. If changes were required when the station was unstaffed, the central control room contacted a local operator to adjust. 

A GEO signal must travel 35,000 km up to a high-orbit satellite, and 35,000 km back down, with a bandwidth of 25-100 Mbps. Even at the speed of light, this takes roughly 240 milliseconds one-way, so uploads from these arctic communities, and downloads to the control facility introduces a minimum delay of nearly half a second. However, LEO signals only need to travel 300-600 km, so latencies of 20-50 milliseconds with bandwidths of 500 Mbps are possible.

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Our original solution was designed for GEO’s longer latencies and anticipated dropped messages by only transmitting change-of-state information to reduce  data amounts sent and using a protocol that automatically manages lost transmissions with an inherent-buffer capability. We then sent transmissions in a compressed file at the end of each day via alternate means. This relayed all the data to the central repository with an associated algorithm to check for and fill any data gaps.

LEO’s flat performance profile addresses the problems we faced earlier because the local barrens don’t have trees blocking  clear views of the sky. This lets each station get the same 200 Mbps capability. LEO satellites change SCADA backhaul options, but integrating 6G also makes  data-intense applications possible, such as autonomous transportation, real-time updates to manage traffic flows in smart cities, or smart energy to match supply and demand, including fluctuations in modern grids’ renewable energy elements.

With 6G deployment expected around 2029-30, the distinction between satellite and cellular will likely disappear for the end user. Your devices, whether for personal communications or data transmission between control nodes, will simply stay connected to the best available node, whether it's 100 meters away on a pole or 400 kilometers away in orbit with minimal latency or bandwidth concerns. This will certainly help make future backhaul options less daunting.