Effective emergency and natural disaster management depend on the efficient mission-critical voice and data communication between first responders and victims. Land mobile radio system (LMRS) is a legacy narrowband technology used for critical voice communications with limited use for data applications. Recently, long term evolution (LTE) emerged as a broadband communication technology that has a potential to transform the capabilities of public safety technologies by providing broadband, ubiquitous, and mission-critical voice and data support. For example, in the United States, FirstNet is building a nationwide coast-to-coast public safety network based on LTE broadband technology. This paper presents a comparative survey of legacy and the LTE-based public safety networks, and discusses the LMRS-LTE convergence as well as mission-critical push-to-talk over LTE. A simulation study of LMRS and LTE band class 14 technologies is provided using the NS-3 open source tool. An experimental study of APCO-25 and LTE band class 14 is also conducted using software-defined radio to enhance the understanding of the public safety systems. Finally, emerging technologies that may have strong potential for use in public safety networks are reviewed.
There have been relatively limited studies in the literature on PSC that present a comprehensive survey on public safety LMRS and LTE systems. In @cite_186 , authors present a discussion on voice over LTE as an important aspect of PSC and then provide a high-level overview of LMRS and LTE technologies for their use in PSC scenario. @cite_211 @cite_271 , authors survey the status of various wireless technologies in public safety network (PSN), current regulatory standards, and the research activities that address the challenges in PSC. The ability of LTE to meet the PSN requirements, and classifying possible future developments to LTE that could enhance its capacity to provide the PSC is discussed in @cite_194 @cite_226 .
@cite_226 @cite_271 @cite_186 @cite_211 @cite_194
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Effective emergency and natural disaster management depend on the efficient mission-critical voice and data communication between first responders and victims. Land mobile radio system (LMRS) is a legacy narrowband technology used for critical voice communications with limited use for data applications. Recently, long term evolution (LTE) emerged as a broadband communication technology that has a potential to transform the capabilities of public safety technologies by providing broadband, ubiquitous, and mission-critical voice and data support. For example, in the United States, FirstNet is building a nationwide coast-to-coast public safety network based on LTE broadband technology. This paper presents a comparative survey of legacy and the LTE-based public safety networks, and discusses the LMRS-LTE convergence as well as mission-critical push-to-talk over LTE. A simulation study of LMRS and LTE band class 14 technologies is provided using the NS-3 open source tool. An experimental study of APCO-25 and LTE band class 14 is also conducted using software-defined radio to enhance the understanding of the public safety systems. Finally, emerging technologies that may have strong potential for use in public safety networks are reviewed. Public Safety (PS) organizations bring value to society by creating a stable and secure environment. The services they provide include protection of people, environment and assets and they address a large number of threats both natural and man-made, acts of terrorism, technological, radiological or environmental accidents. The capability to exchange information (e.g., voice and data) is essential to improve the coordination of PS officers during an emergency crisis and improve response efforts. Wireless communications are particularly important in field operations to support the mobility of first responders. Recent disasters have emphasized the need to enhance interoperability, capacity and broadband connectivity of the wireless networks used by PS organizations. This paper surveys the outstanding challenges in this area, the status of wireless communication technologies in this particular domain and the current regulatory, standardization and research activities to address the identified challenges, with a particular focus on USA and Europe. Public safety communications users in the United States are living in times of unprecedented change. From the challenges associated with the FCC's recent LMR narrowbanding mandate, which limited mobile radio channel bandwidths to 12.5 kHz, to the creation of FirstNet, the world's first, all-LTE public safety broadband network, public safety practitioners are changing the way they react and communicate during times of need. Though the network architecture for FirstNet has yet to be defined, an IMS-based VoLTE solution is the likely voice application successor to LMR push-to-talk and group calling. However, it remains to be seen whether or not VoLTE can provide the features and quality of service that public safety professionals have come to expect and rely on. And the problem is not confined to emergency responders in the United States - the worldwide community of P25 and TETRA users are evaluating the value of migrating to an LTE-based emergency communications network as well. This paper offers a high level discussion on the history of LMR, the basics of LTE and VoLTE, and implementation and testing recommendations based on possible FirstNet architectures. As society continues to integrate information-based technologies into daily life, there is an increased need for small, powerful mobile phones. Recently, relaying technologies have been researched for standardization of the next generation of mobile communication systems, including third-Generation Partnership Project (3GPP) LTE-Advanced, IEEE 802.16j, and IEEE 802.16m. Especially, LTE-Advanced is an evolutionary version of IMT-2000 defined by the ITU. To satisfy these requirements, relaying technology is considered as a powerful candidate scheme with carrier aggregation, MIMO, and CoMP. Relaying technology has been introduced to guarantee high data rates to multiple users. It can also extend cell coverage or effectively increase the average throughput of the cell by installing relay nodes at cell edges or in shadow areas. Thus, in this paper, we propose a method for boosting reception performance using the downlink transmission method of the LTE system, which is the next-generation mobile communication technology standard currently underway in 3GPP. At the moment, orthogonal frequency division multiplexing (OFDM), which is suitable for high-speed data transmission and multipath, is commonly used in an LTE downlink system. However, the OFDM method has a disadvantage of displaying a relatively higher PAPR at the terminal since it basically uses a multi-carrier. To this end, single carrier division multiple access (SC-FDMA) is used in an LTE uplink system in order to compensate for this defect related to high PAPR of OFDM at such an important terminal where power efficiency is important. However, when the channels in the frequency domain deteriorate signals, SC-FDMA reveals a defect in that the impact of deteriorated parts spreads and causes performance degradation. To this end, we propose that a relay be installed between the station and terminal, the distance between BS and RS be set at 500 or 1,000 m, and orthogonal frequency division multiple access (OFDMA) and SC-FDMA be chosen as transmission methods of RS. This paper found SC-FDMA to be a better choice when RS is closer to BS, whereas OFDMA is a better choice when the distance between BS and RS is farther. The system's reception performance improved when the transmission method fit the circumstances in the middle between BS and MS.