So, although PTT over LTE is not yet fully mission-critical, the gap is closing fast.For carriers looking to own the future of their distribution channels, having a reputational advantage with downstream agencies and their producers is mission critical. In the US, FirstNet will be a powerful promoter and proving ground for MCPTT and provide the necessary experience for future improvements to PTT over LTE. LMR radios, with higher transmission power, external antennas, and use of lower frequencies (with superior propagation) do a lot better in Direct Mode. However, typical LTE devices are designed to transmit at low power (generally around a quarter of a watt) at high frequencies through internal antennas, so the range of ProSe is quite limited. To meet this 3GPP created a specification for LTE Proximity Services (ProSe) that define how to achieve device-to-device communications for voice (MCPTT), data (MCDATA) and video (MCVIDEO). While FirstNet provides interoperable communications for all of its subscribers, the ability of FirstNet subscribers to MCPTT outside of FirstNet, either to other LTE networks or to legacy LMR systems is a point of continuing discussion.įinally, Direct Mode for LTE is still a challenge. Third, there is the question of interoperability between LTE networks and between LTE and legacy LMR.

FirstNet does have the right features, but many public networks do not. Second, unless MCPTT runs over LTE networks that support quality of service, call prioritization and call pre-emption, the reliability and availability of communication will still not meet public safety expectations.

Not public safety grade, not rugged, and not built with dedicated PTT or emergency alert buttons. Deployments of MCPTT to public safety have begun, so MCPTT will be tested in real life situations.ĭoes this mean that the issue has been settled about whether PTToC is mission-critical? Not quite.įirst, let’s remember that most of the devices available today for MCPTT are standard consumer products. In response, both carrier-based and OTT PTToC vendors have announced plans to modify or upgrade their own offerings to the MCPTT standard and FirstNet/AT&T has insisted that its PTT will be fully compliant. by the National Public Safety Telecommunications Council (NPSTC), including a plan for integrating LMR and LTE. MCPTT is 3GPP’s answer to the issues discussed in the previous topic, namely, an open standard PTT over LTE specification that meets the mission-critical requirements as identified in the U.S.

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