Future evolution of public safety communications in the 5G Era

Abstract

Public Safety (PS) or Professional Mobile Radio (PMR) communications technologies are undergoing significant transformation towards broadband. The Terrestrial Trunked Radio (TETRA) as one of the earliest critical communication systems has evolved from narrowband data in its first release to the current wideband data Tetra Enhanced Data Service (TEDS). TEDS gives higher data rates with up to several hundred kbit/s and very well fits into the existing PMR frequency landscape. The APCO25 suite of standards in North America had a similar evolution. While still providing essential PMR services like voice, group calls and messaging, the evolution of Public Safety communication must include data-rich broadband services to support a wide range of applications to enhance the operational capability of PMR users. Examples of services and applications include remote healthcare, video-streaming and health monitoring of the first responders. In comparison to mobile applications in the consumer market, PMR applications have severe requirements in terms of signal quality, security, reliability, and coverage. In addition, the usage patterns can be significantly different from the consumer market, as public safety officers must often face unexpected situations (e.g. emergency crisis) and still be able to rely on full traffic capacity and high Quality of Service (QoS) from the networks. The design of future PMR communications must take into consideration these requirements and needs. Significant advances have been achieved in the last years and are still under development focusing on the use of advanced signal processing techniques using flexible mul-ticarrier waveforms in PMR bands to satisfy emerging new data service needs in cohabitation with existing networks in the same frequency bands, to facilitate a smooth migration towards broadband systems and to increase spectrum efficiency. One example is Spectrum sharing, which is expected to bring substantial benefits for a better use of the radio spectrum, helping to mitigate the severe spectrum scarcity problem (mainly in the EU PS band). However, there are several issues that put a question mark on the deployment of PMR systems and their integration with fifth generation (5G) communication technologies and vision. First of all, the integration of PS system in LTE-Advanced (LTE-A) is still not optimized for voice calls (and especially not for the group calls), meaning that it will have to coexist for some time with the PMR conventional networks (e.g. TETRA) for basic voice services. Moreover, LTE-A is still not designed as a mission critical system. High availability and security features are not inherent in all the aspects – so some add-ons to the LTE-A standard or implementation scenarios have to be made, especially in the case of future interoperability and usage of commercial 5G networks for PS scenarios. In addition, standards for direct communications, like LTE Device to Device (D2D) or ad-hoc networks, must be still validated on the basis of the requirements of security and reliability. With proper implementation of these concepts, PMR users may rely on future 5G systems in the same manner they rely on the current narrowband PMR systems. Meanwhile, the design and integration of parallel or complementary usage of traditional PMR systems for voice communication and next generation PMR users in 5G systems for mission critical broadband data transfer still remain as open challenges. In particular, the research and standardization for internetworking of heterogeneous networks for PMR is still not completed. This special issue aims to investigate all aspects relevant to the development of the PMR communications systems and networks and their future evolvement in the fifth generation (5G) communication environment. We received over this special issue ten submissions altogether; out of which, eight were accepted through a rigorous peer review process. Note that in the following sections, the terms PMR and PS are used with the same meaning. In this context, the work presented in the paper Analysis of strategies for progressive 5G emergency network deployment by Vilhar et al. provides an analysis on network deployment strategies. It is evident that the temporary communication systems for emergency situations have traditionally been provided by a single communication technology. They are typically based on the 2G technologies for mobile radio that cannot meet the data rate requirements of contemporary applications. Emergency systems based on the 3GPP LTE technology are presently under investigation, and there is an increasing interest in including new 5G concepts. 5G may enable the employment of multiple heterogeneous communication systems such as fast deployable areal platforms, ad-hoc portable terrestrial stations and satellite communications, all of which integrated with the preserved part of the existing wireless infrastructure. Such an integrated approach is studied and evaluated in this work, based on the simultaneous use of the remaining terrestrial systems and additional LAPs (Low Amplitude Platforms). Simulations of the system were performed using the GRASS-RaPlaT tool, augmented