Panelists note public-safety benefits in LTE standard, cite work that needs to be done
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Panelists note public-safety benefits in LTE standard, cite work that needs to be done
Public-safety representatives understand that FirstNet needs to sell unused capacity on its broadband network to generate revenues that will allow it to offer lower-cost services to first responders, but it is critical that the proposed broadband system be available to public safety when an emergency occurs, Burchnell said.
“It is public safety’s network, and the expectation is going to be ruthless preemption of secondary users that are not public safety,” Burchnell said. “That expectation is non-negotiable from a public-safety standpoint. So, how do you do that in real time—on the fly—as events evolve? I think that’s the value in the system.”
But Olbrich said that—unlike LMR preemption, in which other users lose all ability to use the network—there is a much greater likelihood that commercial users sharing the FirstNet system would see significantly slower data speeds during times when public safety needs additional capacity in a given cell sector. While such service-degradation is built into the LTE standard, actually kicking a commercial customer off of the network entirely would be reserved only extreme cases, he said.
“In LTE, preemption is very different; you have multiple bearers,” Olbrich said. “Think about your phone: You may have a Facebook session going on; you may have Netflix that you’re watching; you may have a voice call; and you may be texting someone. If you have an Android or Apple phone, you can see all of your applications running in the background.
“Preemption in the LTE world means that I preempt one of those bearers. So, the bearer that [commercial customers] are perhaps using for Netflix goes to a lower precedence, and now my public-safety application takes precedence.”
In those cases that outright preemption is used, public-safety officials should establish clear policies to ensure that such actions do not have negative unintended consequences, according to audience member Claudio Lucente, a consultant for the Centre for Security Science-Defense Research and Development Canada.
“How do you know that, in preempting a session, that you’re not preempting a 911 call that’s happening in the same area or the same cell sector, or [a session] between a medical specialist and somebody providing advice for a cardiac arrest?” Lucente said. “You don’t want to preempt that. So, you have to be able to distinguish that [kind of] session from other public sessions that are going on.
“Then, how do you also use that mechanism when there are uncorrelated public-safety events occurring in the same sector. Do the incident commanders check with each other? I think this issue of preemption and priority needs to be taken beyond just the incident-specific event. It should be looked at from the perspective of what could be impacted—what are the domino effects of utilizing this trump card?”