Southern Linc turns to Ericsson for MCPTT with eMBMS, replacing Motorola Solutions WAVE 7000

Southern Linc—the southeast U.S. regional carrier that also provides communications for the Southern Company utility—is deploying Ericsson’s mission-critical-push-to-talk (MCPTT) solution with eMBMS broadcast capability that is scheduled to be used by utility workers by the end of the year, according to a Southern Linc official.

Southern Linc’s network operates on 3 MHz of 800 MHz spectrum, providing the primary communications supporting Southern Company utility personnel, as well as commercial service to consumers in the southeast U.S. Southern Linc utilizes Ericsson’s end-to-end LTE system, which was selected to succeed the carrier’s legacy iDEN network supported by Motorola Solutions that was shut down completely last year.

A similar transition is occurring in the push-to-talk-over-LTE space for Southern Linc. Ericsson’s Group Radio MCPTT solution is slated to replace the WAVE 7000 push-to-talk technology from Motorola Solutions within two years, according to Alan McIntyre, Southern Linc’s director of engineering.

“We’re going to [deploy Ericsson MCPTT] in stages,” McIntyre said during an interview with IWCE’s Urgent Communications. “It’s really a developmental effort with Ericsson. We provided them with close to 500 feature requirements, and we’re working with them to incorporate all of that functionality into their product.

“We have a set of features that will get our operating companies within Southern Company—Alabama Power, Georgia Power and Mississippi Power—to start using the product. We can start focus groups or test groups pretty soon with the version [of MCPTT] we have right now.”

Based on the feedback received from these initial tests and updates from Ericsson, Southern Linc believes the MCPTT service will be ready to serve as the primary communications technology for these utility workers, McIntyre said. Ericsson’s MCPTT expected to be offered for use outside Southern Company in 2021, he said.

“We’ve got a few other features that we want to include during the first part of next year that really will kind of hit the mark for our public-safety users,” McIntyre said. “It will probably be the middle of next year before we go fully commercial live with it [to include commercial enterprise use]. So, we’ve got a little over a year of testing and implementation to go.”

One key characteristic in the Ericsson MCPTT platform is the integration of evolved Multimedia Broadcast Multicast Service (eMBMS), which is a 3GPP standard to support broadcast communications that can support group calls efficiently, rather than utilizing traditional one-to-one LTE communications.

Given the fact that Southern Linc’s LTE network operates on just 3 MHz of spectrum—compared to more than 150 MHz below 6 GHz licensed to AT&T—having eMBMS was a “table-stakes requirement” for an MCPTT solution, according to McIntyre.

“Think about large generating plants; there may be 500 users there,” he said. “If there’s an emergency, they have an emergency group, and they want to be able to communicate with everybody at the plant at one time. So, from a capacity standpoint, eMBMS is critical in those situations.”

This group-call capability enabled by eMBMS is even more important during power outages, construction periods or in the aftermath of natural disasters, such as a hurricane, McIntyre said.

“Our operating companies in those cases will set up staging areas … with a large number of users,” McIntyre said. “They can set up a tent city overnight and have a thousand or more linemen in that tent city.

“Having eMBMS when you have that kind of collection of folks in a very, very small area is critical to us.”

Rishi Bhaskar, Ericsson’s vice president of utilities and the public sector, said the Ericsson Group Radio MCPTT features are compliant with LTE Release 14.

“From what we can tell, [the Southern Linc deployment] would be the first full eMBMS integration in the world for MCPTT,” Bhaskar said during an interview with IWCE’s Urgent Communications. “We’re very excited about it, and we’re looking forward to building on this momentum in the market.

“It’s an industry first, and it takes a leader like Southern to really push the envelope and a partner like Ericsson to deliver it. We’re excited about the opportunity.”

AT&T has announced plans to unveil an MCPTT offering to FirstNet users by the end of March, but no details have been released yet about the vendor—or vendors—supplying MCPTT or the specific features associated with it.

AT&T, Verizon and U.S. Cellular have all said that priority and preemption are available to first responders on their networks—functionality that is also supported on the Southern Linc LTE system, according to Bhaskar.

“Priority and preemption capability is available, and it ties into the network,” he said. “MCPTT over LTE—and 5G forthcoming—is a huge stride for the industry, but the real enabler is the network.

“The policies and controls that we put in the network to enable priority goes through to the PTT application, because we are an integrated solution. Really, what this does is put this on a path for our mission-critical customers to be a true one-network solution for voice, video and data.”

Both McIntyre and Bhaskar said that the Ericsson MCPTT solution has performed well in the Southern Linc laboratory, meeting the demanding 3GPP specifications for characteristics like call-setup times.

McIntyre said he believes Southern Linc users will be pleased with the voice quality of MCPTT, which he expects to improve as higher-level vocoder technology can be integrated in the future.

“People loved iDEN, but it had a VSAT vocoder,” McIntyre said. “With WAVE, we’ve been able to go to AMR. I think we’ll have even more capabilities with Ericsson’s Group Radio platform. We want to really evolve into an EVS vocoder—that’s what we’re using on our VoLTE system now with an Ericsson IMS, and people love the voice quality on our VoLTE side right now.”

“Directionally, we’re continuing to get better on voice quality with push to talk. That’s the other positive about Ericsson—I think they’ll continue to evolve the product, providing enhancements and updates.”

Other key features of the Ericsson MCPTT platform for Southern Linc are a web-based portal to manage talk groups, and a playback feature that lets users replay the audio of PTT calls they have missed or simply want a repeat of instructions provided in a call, McIntyre said.

Ericsson’s Group Radio MCPTT also has a “very nice dispatcher client” with mapping capabilities that is promising, according to McIntyre.

“There’s a dispatcher client for [Ericsson] Group Radio—a PC-based client—and we really think it has the ability to displace consoles,” he said. “So, where we traditionally have done consoles with donor radios, we really think this has the potential to replace a lot of that out in the field.

“Again, Ericsson is working with us and our operating companies. The folks that are using console radios now are involved in providing input, so we really think that’s going to be beneficial, as well.”

Most public-safety industry experts believe MCPTT can meet or exceed the mission-critical PTT when the user is able to access the LTE network, but there are significant concerns about the MCPTT when LTE is not available. The 3GPP standard includes a direct-mode standard known as Proximity Services (ProSe), but chipsets supporting the technology are not widely available. Even if ProSe is implemented and works, the lack of power and external antennas in typical LTE devices mean that that the signal range of this direct-mode option likely will be limited.

With this in mind, Southern Linc has been working with Sonim Technologies on the development of an direct-mode accessory that attaches to the top of rugged Sonim devices and uses LoRaWAN—a low-power, wide-area networking protocol—that operates on unlicensed 900 MHz spectrum.

“It provides about a mile of coverage,” McIntyre said. “We’re testing it now. We haven’t really released it full scale.

“It was a development effort with Sonim … We’ve been working with them and going through several iterations. Right now, it looks like we finally hit the mark, so we’re excited about it.”