PTT-over-cellular solutions make compelling case for LMR replacement, webinar speakers say
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PTT-over-cellular solutions make compelling case for LMR replacement, webinar speakers say
Newburn said that Fairfax County has experienced no latency problems and realized “better fidelity” with the PoC solution. Olbrich said the voice-quality assessment is consistent with industry tests of mean opinion scores (MOS) associated with PoC applications, noting that LMR systems use lower-level codecs that are critical to determining voice quality.
“Wideband AMR codec [the codec used for PoC] MOS scores, on average, are 4.1 or 4.2 out of 5,” Olbrich said. “With LMR P25, you can maybe get to 3—and that’s under ideal conditions.
“So, it’s not even a contest, with regard to voice quality. Even under duress and under poor conditions, you have a much wider frequency-response range—typically, the codec just operates better, even under bad conditions.”
PTT also is integrated much better into devices today than in the past, with many boasting dedicated PTT buttons like those found on LMR subscribers, Olbrich said.
“So, it’s not like before, where you had to swipe your phone, put in your code, run the app and then push to talk,” he said. “These phone have dedicated buttons that are just like a LMR radio, insomuch as they’re always on—you push a button, you talk, it works.
“They are highly integrated and optimized for call-setup time and for battery life.”
Olbrich noted that carriers are providing prioritization and quality of service to PoC solutions in an effort to deliver greater reliability and performance to PoC users, but PoC traffic does rank behind voice-over-LTE (VoLTE) traffic in carriers’ prioritization schemes today. That will not be the case with MCPTT, which will be given the higher prioritization than VoLTE traffic, he said.
In March, 3GPPP—the standards body that oversees LTE technology—approved most of the MCPTT standard, which is designed to PoC services that would meet public-safety standards for performance and reliability, including off-network direct-mode capabilities and the ability for an LTE cell site to continue local operation even if connectivity to the evolved packet core is lost, Olbrich said.
Existing PoC offerings already meet the MCPTT standard, from a functionality standpoint, Olbrich said. The big difference is that MCPTT will have additional network requirements that are designed to provide the kind of performance and reliability that public-safety users demand, he said.
With the deployments of public-safety LTE systems such as FirstNet in the United States and Safenet in South Korea, real-world experience with MCPTT should begin as early as next year, Olbrich said.
“One thing to note is that MCPTT is here; there are early trials going on,” he said. “[South Korea] started in 2015; in 2016, they’ll be nearly done with the entire country; and by the end of next year, the entire country—plus 200 kilometers off the coast of Korea—will have mission-critical-push-to-talk LTE coverage for first responders.
“So, this is not something that is way off in the future, is difficult to instantiate, is impossible to do, or will take many, many years to happen. It’s happening now, as we see it.”
Oh, how I read this and
Oh, how I read this and wonder where these people come from? I just can’t wait for the first time a storm blows through the fairfax county area and all heck breaks loose. The poc server fails, cells go down, fiber on poles get damaged, and the entire team of dpw is sitting there playing pre loaded word games on their cell phones because the system is down and they can’t talk.
Let’s further this crazy argument. “These” people that have slithered out from under the rocks to tout the digital best codec, best audio quality are insane. Who ever said that analog audio wasn’t the best for voice quality. Why is p25 even being discussed for local government functions? I get it, you want to take advantage of spectrum efficiency and other digital features, but to sacrifice voice quality, maybe not? It was these same people who stood on their soap boxes and said, p25 must be for public safety, must be for interoperability. We all know know that is complete BS, as p25 had little to do with furthering any interop. It was a cleaver and clean way for the manufactures and our friends, the government to forcefully line their pockets. They even went so far as to lobby and push the government to extort public safety users with withholding vital grant monies if equipment purchased wasn’t p25 capable. Oh, how history repeats itself. Please, just go away and leave public safety alone. Go pedal the cell phones to the kiddies.
Anonymousradiousers clearly
Anonymousradiousers clearly has an ax to grid and the facts don’t matter because he/she knows that the facts presented by Fairfax just can’t be real.
Has very little to do with
Has very little to do with “fairfax county” other than they were used in the article. Rather, this is an industry wide trend being pushed by media, sales people, and the industry fat cats to line their pockets with the next big thing. The entire thing is sickening, especially when public safety is being used as the pawn. I have the facts, I have the real world experience. What I lack is the used car salesman sliminess that allows me to fully understand all the underlying motives.
p25 is now a waste of time,
p25 is now a waste of time, most if not all major networks are so integrated with telco networks they are bound to fail, on top of that the hub and spoke technology stacks used are just setting it up to fail more in the event of a major issue.
With First responder they are sick of caring to much oversized, over priced single service crap.,…. your comment ‘Go pedal the cell phones to the kiddies’ just goes to show how out of touch you are.
P25 was a waste of time the
P25 was a waste of time the minute it rolled out to the market.
I am far from out of touch. What is out of touch is private industry colluding with the federal government to build a network that is technically not feasible, and provide coverage that commercial carriers aren’t even willing to or want to provide to charge public safety users to use, but will make the spectrum and system available back to the commercial carriers on devices and technology that doesn’t yet exist, and by the time it does the entire platform will be replaced twice over. All on the taxpayers dime. And I’m out of touch, I don’t think so. Oh, by the way another strong arm by the private industry and government, those frequencies you are currently on, we are gonna take them away from you and force you to go on our system, for a fee of course.
I totally agree. I think most
I totally agree. I think most industry players would be surprised at how many in the PS community would support these sentiments – or they’re too greedy to care.
Im curious, what makes
Im curious, what makes backhaul on a PS network any better than a commercial network? Maybe PS uses microwave but so do commercial networks. Yes commercial networks use fibre, but so does PS – sometimes leased from commercial carriers other times they use their own (purpose built or municipal). Commercial carriers have the expertise to recover their networks quickly – they’re losing millions $$ per day if they go down. For the same reason they have the same level of redundancies built in that PS does – sometimes better.PTT on commercial networks supports QoS so during times of congestion, PTT has a good chance of getting through. PS networks also suffer from congestion during major incidents as users react to the situation. I’m not an advocate of commercial or P25 networks but each has its own benefit and at the end of the day the network you choose is based upon what you can afford. It’s up to the decision makers to determine if the chosen network meets their operational and emergency preparedness requirements.