Officials for AT&T, Nokia outline capabilities of upcoming MCPTT-compliant solutions

Voice services meeting the mission-critical-push-to-talk (MCPTT) standard developed by 3GPP—the body that oversees LTE development—will provide greater voice quality, performance and reliability than any push-to-talk-over-cellular (PoC) offering available on the market today, officials from AT&T and Nokia said yesterday.

Dharmesh Tyagi, Nokia Networks’ head of special solutions for public safety and private LTE, said that all current PoC solutions are over-the-top applications, although carrier-integrated offerings—for instance the offering from Kodiak, which is now owned by Motorola Solutions—provide a level of optimization at the application layer. In contrast, the Nokia MCPTT solution is designed to be embedded in the carrier’s LTE evolved packet core (EPC), so it also can optimize performance at the network layer, he said.

“Compared to enhanced (PoC), MCPTT is a completely different ballgame,” Tyagi said yesterday during an IWCE webinar sponsored by AT&T and Nokia (listen to the archive with free registration). “You’re talking about way less latencies and very high … voice quality.

Indeed, multiple report and studies indicate that the voice quality possible with MCPTT on an LTE network is much better than typical LMR push-to-talk communications. At the heart of the heart of this difference is that MCPTT utilizes an advanced codec, according to Tyagi.

“With mission-critical push to talk, we are using Wideband AMR [Adaptive Multi-Rate Wideband], which is high-definition voice quality, he said. “So, when someone makes a push-to-talk call using MCPTT, they’re getting the highest quality available on the market.”

Nokia does not have a PoC product on the market today, but the company has developed an MCPTT solution that has been tested in AT&T’s laboratories and is being trialed by carriers in South Korea and Europe.

Tyagi said the tests have gone well, with the Nokia MCPTT solution performing much better than the 3GPP standard requires. Particularly notable is the fact that total call-setup time for the Nokia MCPTT offering is “about 200 milliseconds,” well below the 1-second threshold included in the standard, Tyagi said.

Although the MCPTT standard does not specify that a solution must be embedded or integrated tightly in the carrier’s network, Tyagi and many other industry experts believe such integration is needed to meet the performance criteria in the MCPTT standard.

Igor Glubochansky, assistant vice president of mobility management for AT&T—the carrier contracted to build FirstNet’s nationwide public-safety broadband network (NPSBN)—echoed this sentiment.

“When it comes to mission-critical push to talk, there are going to be specific mission-critical capabilities that the MCPTT solution will need to tap in the network that allow the solution to [meet] the KPIs prescribed in the standard,” Glubochansky said during the webinar. “With that requirement to meet those KPIs—from a laws-of-physics perspective—network-integrated solutions with tight integration with devices … will be most likely imperative for moving forward.”