Public Safety Networks

  • 07 Dec 2018
  • Chris Hogg - GCF Office

Public Safety Networks (PSNs) play a key role in supporting first responder agencies such as police officers, firefighters, and ambulances. Historically these networks have been based on dedicated infrastructures, with systems and equipment designed to meet the specific communications needs of the emergency services. Although economically and socially important, the market for public safety systems is small in comparison to commercial wireless networks and lacking economies of scale, does not attract the same levels of global investment and R&D. Consequently, PSNs have not enjoyed the same levels of innovation as commercial networks and existing technologies such as TETRA and P25 that have been in use for over 20 years. Whilst mature, reliable and cost-effective in supporting mission-critical voice, these technologies were not designed to support higher bandwidth applications such as video and data.

Public Safety Agencies (PSAs) tend to be highly mobile and being exposed to the benefits of mobile broadband in their private lives, have unsurprisingly found ways of supplementing their voice communications through private networks with carrier network voice and mobile broadband data. Regular consumer devices such as smartphones, tablets and notebooks have tended to be used by PSAs to access this broadband functionality, leading to the less than satisfactory situation where operators often need to carry multiple devices.

This growing reliance by PSAs on broadband services is creating pressure to consolidate all the required functionality for voice and data communications, as well as the specific capabilities of the two-way radio devices into a single device; such a device operating on a Public Safety Mobile Broadband (PSMB) network would satisfy all PSA communications needs.

With this evolving demand from the PSAs, it has become attractive to leverage existing public carrier networks for the provision of mission critical services. However, until recently, commercial wireless networks have not been a viable alternative, with consumer LTE networks needing several upgrades to handle the specific needs of first responders and associated government agencies, which include:

  • Push-to-Talk - the “walkie-talkie” calling model between two or more parties where one speaker at a time has the ability to transmit voice. 
  • Voice intelligibility - critical communication devices must be able to deliver clear audio (i.e. high MOS). Noise cancellation and other techniques may also be required in loud or windy environments.
  • Group calling & messaging - one-to-many, many-to-many and dispatcher modes allowing communications among various emergency services teams.
  • Prioritization & pre-emption of first responder traffic, and the corresponding pre-emption of other traffic are key to LTE’s ability to support mission critical communications. In crowded networks, consumers can be dropped while first responders are recognized and given the highest priority access.
  • Proximity services (PoSe) & device-to-device (D2D) communication allow devices to discover each other, to communicate directly and to form meshes. These capabilities enable communication where there is no network coverage.
  • Mission critical video calling allows two-way real-time person-to-person calling, (3GPP’s R14 Mission Critical Video (MCVideo) over LTE also provides for multi-party calls).

Despite the inherent limitations of commercial LTE networks, a number of countries including the United States, United Kingdom, South Korea, Australia and Finland have gone ahead and developed public safety over LTE (PS-LTE) network solutions for mission critical services. 

In parallel, 3GPP- the standardization body governing world-wide cellular networks, has actively supported these developments by rolling out new specifications to support mission critical communications in the R13 (2016), R14 (2017) and R15 (2018) releases of the LTE specifications, as summarised in Table 1. The initial focus, in Release 13, was on MCPTT providing enhanced voice-based push-to-talk communication based on the 3GPP Evolved Packet System (EPS), leveraging Group Communication System Enablers (GCSE) and Proximity-based Services (ProSe). 

Release Release 13 Release 14 Release 15
Date March 2016 September 2017 June 2018
Functionality MCPTT MCPTT enhancements
MC Data
MC Video
MCPTT enhancements
MC Data enhancements
MC Video enhancements

Table 1: Overview of MC functionality in 3GPP releases

Given that life is often at stake, it is of critical importance that the emerging range of mission critical devices for LTE networks inter-operate correctly with the networks. In this regard, the importance of conformance to standards and interoperability is well recognised in the wireless industry and GCF has been providing trusted certification services to the industry for over 20 years.

In January of this year, GCF announced the extension of its certification scheme to cover LTE-based critical communications devices with a new Work Item covering MCPTT over LTE being approved by GCF’s Steering Group in December 2017. This work item is currently well underway and MCPTT certification will be included in the GCF portfolio as soon as the relevant tests are validated and available on commercial test equipment.

The advantages in terms of quality and service reliability of ensuring the interoperability of mobile devices is well understood, with data proving that GCF members’ products have up to 20% fewer dropped calls than non-certified products. In an emergency situation, where human life depends on it, communication simply cannot fail and therefore, with mission critical devices, certification against 3GPP standards is paramount.

The emergency services network operators, device suppliers and the test industry are therefore strongly encouraged to join GCF, certify their products and use GCF-certified products in their networks as part of a wider strategy to build reliable, high-quality services for critical communications users.


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Chris Hogg - GCF Office

Chris Hogg - GCF Office