LTE developments not until 2018-20

The TETRA & Critical Communications Association has advised the timescales for critical communications services over LTE.

Despite the ongoing rollout of consumer LTE networks, LTE-based data services for mission-critical communications will not be available until 2018 at the earliest, and acceptable quality voice services over LTE for mission-critical users are not expected until at least 2020. These timescales have been published by the Critical Communications Broadband Group (CCBG), a working group of the TETRA & Critical Communications Association (TCCA).

Implementation of critical mobile communications services over LTE demands standardisation both from 3GPP and ETSI. The TCCA CCBG is contributing to these standardisation processes to ensure global consensus for critical mobile communications standards that fully meet users’ requirements while allowing a migration and interoperability strategy for existing technologies in different regions.

"As the world moves to LTE, it is essential that the communications industry operates in a coordinated and coherent way to bring to maturity standards relevant to public safety and other critical users," said Tony Gray, Chair of the CCBG. "We are working to ensure that such requirements are incorporated into the LTE standards effectively.”

Standards due in 2014

There are currently four key areas to be addressed within the LTE standards to enable a suitable foundation for critical communications services. These are group communications system enablers for LTE (3GPP GCSE_LTE); proximity-based services (3GPP ProSe); public safety networks resiliency; and the push-to-talk (PTT) voice application standard over LTE and its evolution toward multimedia (voice, data, video, etc) group communications.

The CCBG and its partner stakeholders around the world have achieved a significant breakthrough in having the first two of these accepted by 3GPP as work item descriptions (WIDs) that will be incorporated into Release 12 of the 3GPP LTE standards specification, planned for publication at the end of 2014.

Group communications system enablers for LTE are designed to address the 3GPP standards evolutions needed to support group communications of various media (voice, video, messaging, etc) over LTE. They are based on input requirements provided by the major international public safety and critical communications user organisations including APCO, EUTC, LEWP-RCEG1, NPSTC, PSCE, UIC and others. Proximity-based services are designed to address both critical communications and commercial requirements for direct mode or proximity (‘device-to-device’) services on LTE.

Critical networks resilience is an additional area of weakness in existing LTE network design. Compared with current critical communications technologies, there is no capacity for ‘graceful degradation of service’ should the connection between the base station and the core network be lost. The objective is to include this evolution in Release 13 of the 3GPP LTE standards specification, planned for publication at the end of 2016.

Still under discussion

Although the first commercial LTE deployments are operational, these are for data-only services. The consumer voice evolution for LTE is still under discussion. Open mobile alliance (OMA) push to talk over cellular (PoC) is a group communication service defined for 2G/3G networks built on top of 3GPP IMS specifications. This does not provide an adequate solution for the delivery of mission-critical voice group communications and a new critical mobile communications application standard has to be produced for new multimedia group communications services. This is expected to be incorporated into the LTE standards post 2020.

“Achieving industry synergy is crucial to ensure uninterrupted availability of mission-critical communications services," said Phil Kidner, CEO of the TCCA. "LTE is currently designed for commercial use. There is no viable replacement on the horizon for the current technologies employed by critical communications users.”

“The work of the CCBG will help to ensure that LTE standards develop to enable a broadband data-only bearer that will initially complement, but not replace, existing critical voice services.”