Collaboration vendor Mutualink recently released a white paper that encourages FirstNet officials to consider what application functionality should be included in various parts of the network—particularly as they relate to deployable systems—to enhance efficiency of the fixed-infrastructure system.

“People are putting the pipes first—and understandably so,” Mutualink CTO Joe Boucher said during an interview with IWCE’s Urgent Communications. “What they’re currently focused on is building out the pipes, with the theory being, ‘We’ll build out the pipes, because—without the pipes—we can’t put any applications on it, so it’s worthless thinking about those [applications].

 “One of the things that I wanted people to take away from that white paper is that architecting the pipes does require some thinking about the applications that are going to ride on those pipes. Because the capabilities you would like to enable with applications will influence how the pipes are built out.”

In particular, LTE architecture requires connectivity to an evolved packet core (EPC) to support application functionality, Boucher said.

“So, if you don’t put a core at the deployable level, you can’t put applications at that level that are using LTE,” he said. “If you only put the cores in the fixed infrastructure, then what you’re saying is that, to get any LTE application-level functionality on scene, I require a certain amount of bandwidth backhaul to reach my core and my application gateways.”

Currently, the 3GPP standards body that oversees LTE technology specifications is in the process of developing peer-to-peer functionality specifically for public safety to support various applications, including mission-critical voice. However, such functionality means that the ability for applications to work is dependent on the capabilities of the devices being used—and often, the capabilities of the devices are not homogenous, Boucher said.

Having an application server and EPC at an incident scene would change that situation and allow applications to function normally, Boucher said. This is significant as FirstNet officials determine what kind of deployable systems should be used in a given circumstance—cells on wheels (COWs) or more-expensive systems on wheels (SOWs), he said.

“SOWs are fully functional systems,” Boucher said. “They can be dropped from a helicopter in remote areas, provide LTE services—as well as application services—to an entire incident area. COWs, however, require backhaul to do anything. They require connectivity to the packet core, wherever it be located.

“And, if you’re backhaul is something like a satellite, which anticipated for the rural areas—you’re going to be able to do only very limited things over that backhaul. So, if public-safety folks think they’re going to be able to do video sharing from a helicopter … with a cell on wheels and satellite backhaul, that’s going to be a rude awakening.”

From a big-picture perspective, Boucher said that COWs make sense in dense, urban environments “where you’re almost guaranteed to get connectivity to the core network,” while SOWs are more appropriate in rural environments and in disaster areas, where broadband backhaul connectivity is an issue.