Public Safety Networks Research Articles

QoS-Aware Frequency-Based 4G+Relative Authentication Model for Next Generation LTE and Its Dependent Public Safety Networks

Increasing demands for high-speed broadband wireless communications with voice over long term evolution (LTE), video on demand, multimedia, and mission-critical applications for public safety motivate 4th-generation (4G) and 5G communication development. The flat IP-based LTE and LTE-Advanced technologies are the expected key drivers for 5G. However, LTE, with its elapsed security mechanism and open nature, leaves a huge loophole for intruders to jeopardize the entire communication network. The time-and bandwidth-consuming authentication procedure in LTE leads to service disruptions and makes it unfit for public safety applications. To cater the prevailing LTE security and service requirements, we propose the 4G plus relative authentication model (4G+RAM), which is composed of two dependent protocols: 1) Privacy-protected evolved packet system authentication and key agreement protocol for the initial authentication (PEPS-AKA) and 2) 4G plus frequency-based re-authentication protocol for the re-authentication of known and frequent users (4G+FRP). The 4G+RAM supports seamless communication with a minimum signaling load on core elements and conceals users’ permanent identifiers to ensure user privacy. We simulate the proposed protocols for formal security verification with the widely accepted automated validation of Internet security protocols and applications tool. A comparative analysis of bandwidth consumption is also performed and proved that the proposed 4G+RAM outperforms the existing solutions.

Analytical Modeling of LTE-based Network Capacity for Public Safety Communications

In this paper, an analytical approach for estimating the network capacity for voice communications on LTE-based public safety networks is presented. The network is modeled using Markov birth and death process. In order to provide the required Grade of Service for LTE-based public safety users, the minimum number of channels required for different levels of users' priority is calculated. The results for some performance metrics such as throughput, delay probability, and channel utilization are obtained. The results obtained from the simulation is compared with the existing network model such as Erlang C. Results show that the existing network model show similarities and differences in predicting the channel estimation of the deployed LTE networks for public safety communications. The results can help the network designer in the proper dimensioning of LTE-based public safety network.

ORACE-Net: A novel multi-hop body-to-body routing protocol for public safety networks

With the growing increase of disasters worldwide, in terms of frequencies, intensities and unpredictability, there is currently a growing need for novel ubiquitous communication systems enabling public safety networks (PSN). Disaster operations require real-time and low latency data communication, in live video and audio streaming, as well as in integration with social networks. In this context, existing network infrastructures might be either damaged or overloaded. Thus, it is expected that wireless Body-to-Body Networks (B2Bs) could play a key role in setting-up tactical PSN deployments enabling effective and reliable disaster response and management. In addition to the challenges with radio technologies and their inter-operability, coexistence and energy consumption issues, routing is also an important and critical challenge for the PSN. In this paper we propose a novel wireless B2B routing protocol, called “Optimized Routing Approach for Critical and Emergency Networks (ORACE-Net)” to enhance routing performance in disaster relief. ORACE-Net aims to exploit dynamic B2B communications between wearable networks to establish and maintain a mobile dynamic communication backbone. Analytical evaluations are conducted to analyze the communication overheads of ORACE-Net in comparison to existing routing standards, including Ad hoc On-Demand Distance Vector version 2 (AODVv2), Optimized Link State Routing Protocol version 2 (OLSRv2) and Greedy Perimeter Stateless Routing (GPSR). Extensive simulations are then performed under realistic assumptions and synthetic mobility models, and show that ORACE-Net outperforms conventional routing approaches in terms of packet reception rate, energy consumption and fairly performed in terms of delay compared to the other approaches.

A novel geometric handover model for aerial 4G networks with WiFi‐based X2 interface

AbstractGiven the temporary nature of radio communications for mission critical scenarios, the existing dedicated public safety network lacks the flexibility of cutting edge technologies to leverage on packet data services. In this context, new challenges arise such as high‐capacity demand and low‐latency flexible backhaul connection for public safety users. In this paper, we consider a scenario in which 4G LTE radio coverage is provisioned by aerial eNodeBs installed on low‐altitude platforms raised in the sky and interconnected through WiFi links. We focus our attention on the critical aspect of theThird Generation Partnership Project handover mechanism studying the handover performance using a X2 interfaces over WiFi links. We develop a novel geometric model of the handover in the context of public safety communications but extensible also to other contexts. Relying on such a model, the handover failure probability is computed taking into account the different handover phases. The coverage area of an aerial eNodeB is studied using a suitable air‐to‐ground propagation model, while the average handover duration is computed taking into account the delay introduced by the WiFi communication dynamics. Copyright © 2016 John Wiley & Sons, Ltd.

Power efficiency, phase noise, and DC offset in constant envelope OFDM transceivers

AbstractThis paper considers constant envelope orthogonal frequency‐division multiplexing (CE‐OFDM) that is an attractive candidate for the future Long Term Evolution over satellite and device‐to‐device communications in merging public safety and commercial networks. The constant envelope modulation allows power amplifier (PA) to operate near saturation levels thus maximizing power efficiency. Because the phase noise transforms just into an additive noise term after the phase detector, the CE‐OFDM has significant advantage compared with phase noise sensitive OFDM. The transceiver power efficiency is evaluated by measuring the bit error rate as a function of average PA input signal‐to‐noise ratio so that the effects of the PA nonlinearities are taken into account in the performance evaluation. Our simulation results show that with a typical nonlinear satellite amplifier, the CE‐OFDM has up to 6.0dB gain compared with the OFDM. This is beneficial especially in a channel having high attenuation. The consistent gains for the ideally linearized amplifier and common terrestrial three‐way Doherty amplifiers are 2.2 and 2.5dB, respectively. The enhanced PA efficiency enables battery to be smaller or last longer in mobiles devices. For CE‐OFDM implementation, a simple transmitter and receiver structure with novel direct current offset removal is presented by keeping in mind that the key factor for the rapid uptake of the future fifth generation systems is the maximization of technology commonalities with existing systems. Copyright © 2016 John Wiley & Sons, Ltd.

Reliable low-energy group formation for infrastructure-less public safety networks

In this paper, we study an infrastructure-less public safety network (IPSN) where energy efficiency and reliability are critical requirements in the absence of cellular infrastructure, i.e., base stations and wired backbone lines. We formulate the IPSN group formation as a clustering problem. A subset of user equipments (UEs), called group owners (GOs), are chosen to serve as virtual base stations, and each non-GO UE, referred to as group member, is associated with a GO as its member. We propose a novel clustering algorithm in the framework of affinity propagation, which is a state-of-the-art message-passing technique with a graphical model approach developed in the machine learning field. Unlike conventional clustering approaches, the proposed clustering algorithm minimizes the total energy consumption while guaranteeing link reliability by adjusting the number of GOs. Simulation results verify that the IPSN optimized by the proposed clustering algorithm reduces the total energy consumption of the network by up to 31 % compared to the conventional clustering approaches.

A Priority-Based Bandwidth Management Method in Public Safety Networks

After Sewol ferry disaster occurred in April 2014, Korean government began investing to deploy LTE-based public safety network until the year of 2017. In order to reduce the operating and capital costs, resource sharing scheme among public safety network and commercial LTE networks is considered as one of the viable approaches. This thesis proposes a method of allocating bandwidth of public safety network based on various priorities required for disaster scenarios and stages in a resource sharing environment. In order to obtain the highest efficiency, we formulate the bandwidth allocation problem as a Fractional Knapsack Problem. Greedy algorithm was applied to solve the problem. For performance evaluation, we created several disaster scenarios and set suitable parameters for each scenario based on a disaster manual. The proposed method is compared with two typical methods, which are Class-based bandwidth allocation and Uniform bandwidth allocation. The results showed that the better performance in terms of the sum of the values and the amount of lost bytes.

Cloud-centric multi-level authentication as a service for secure public safety device networks

With the advances in IoT, future public safety responders will be well armed with devices that pump data between on-site responders and command centers, carrying useful information about the event scene, the status of a mission, and helping critical decisions to be made in real time. In addition, wearable and on-body sensors will monitor the vital signals and well being of the responders. These connected devices or the so-called IoT surrounding public safety responders generate highly vulnerable data, where security breaches may have life threatening consequences. Authentication of responder devices is essential in order to control access to public safety networks. Most of the existing authentication schemes do not scale well with the large number of devices of IoT, and are not fast enough to work during time-critical public safety missions. On the other hand, for general IoT services, cloud-based solutions provide unlimited resources for storing and accessing IoT data. However, the cloud may have some implications for sensitive data that are collected for public safety. Therefore, authentication solutions are desired to integrate well into the cloud environment. In this article, we propose cloud-centric, multi-level authentication as a service approach that addresses scalability and time constraints, and demonstrate its effectiveness. We draw future research directions for secure public safety networks in the presence of IoT devices and the cloud.

Critical communications and public safety networks, part 2: technical issues, security, and applications [Guest Editorial

As we mentioned in the Guest Editorial of Part 1 of this Feature Topic, which was published in March 2016, due to a high number of high quality submissions, we divided the accepted papers into two parts. While the articles in Part 1 focused on general topics such as overview, spectrum policies, and economics, the articles of Part 2 in this issue of the magazine focus on more technical issues and solutions.

LTE/LTE-A jamming, spoofing, and sniffing: threat assessment and mitigation

LTE is currently being proposed for use in a nationwide wireless broadband public safety network in the United States as well as for other critical applications where reliable communication is essential for safety. Unfortunately, like any wireless technology, disruption of these networks is possible through radio jamming. This article investigates the extent to which LTE is vulnerable to RF jamming, spoofing, and sniffing, and assesses different physical layer threats that could affect next-generation critical communication networks. In addition, we examine how sniffing the LTE broadcast messages can aid an adversary in an attack. The weakest links of LTE are identified and used to establish an overall threat assessment. Lastly, we provide a survey of LTE jamming and spoofing mitigation techniques that have been proposed in the open literature.

Public safety networks evolution toward broadband: sharing infrastructures and spectrum with commercial systems

Nowadays, efficient communication technologies are of paramount importance to provide effective and reliable emergency management systems. New wireless communications engineering approaches and value-added services could lead to great benefits, improving situational awareness and enhancing life-saving capabilities. For these reasons, governments and organizations involved in public safety and security (PSS) are devoting great interest in the transition from existing narrowband wireless systems toward broadband. For this purpose, a viable solution is to adapt the new LTE-A technology in order to provide IP-based broadband services with security and reliability characteristics typical of PSS networks. However, the migration of these systems to LTE-A is currently a critical issue. Costs, timing, and spectrum availability for the deployment of a PSS-dedicated network are demanding. In addition, providing mission-critical services on an LTE-based PSS system needs a proper network architecture solution in order to achieve and maintain required performance and reliability levels. To fully accomplish this task, research efforts can result in significant improvements and adjustments of future releases of the LTE-A standard. This article focuses on critical issues that impact PSS communications evolution toward new technologies and describes the related possible steps, starting from the exploitation of the already deployed LTE-A commercial networks up to a fully PSS-dedicated network infrastructure. Finally, advanced solutions are described and critically discussed.

Multiple preemptive EDCA for emergency medium access control in distributed WLANs

The increasingly use of wireless local area networks (WLANs) in public safety and emergency network services demands for a strict quality of service (QoS) guarantee especially a large number of users report an emergency for immediate channel access. Unfortunately, the traditional IEEE 802.11e-based enhanced distributed channel access (EDCA) does not support a strict QoS guarantee for life saving emergency traffic under high loads. Previous studies have attempted to enhance the performance of EDCA called the Channel Preemtive EDCA (CP-EDCA) which is a promising idea to support emergency traffic in WLANs. However, CP-EDCA supports a single emergency traffic only (i.e. no emergency service differentiation) with high delays for increased traffic loads. To overcome this problem, we propose a class of EDCA protocol called Multiple Preemption EDCA (MP-EDCA) as a candidate to support multiple emergency traffics under high loads. Each MP-EDCA node can support up to four emergency traffics (life, health, property and environment) with different priorities in addition to support background (non-emergency) traffic. The proposed protocol privileged the high priority life-saving emergency traffic to preempt the services of low priority ones without much starvation in the network to maintain a strict QoS guarantee. The paper evaluates the performance of MP-EDCA through an extensive analysis of simulation outcome. The results obtained show that MP-EDCA outperforms CP-EDCA in achieving lower medium access control and emergency node delays.

3GPP device-to-device communications for beyond 4G cellular networks

Since 2012, 3GPP Release 12 (the beyond fourth generation (B4G) network) has been adopted as the next generation public safety network to be deployed in 2015. In addition to conventional high data rate transmissions in LTE-A, a public safety network is required to further support communications for users out of base station (BS) coverage. Avoiding any signal relay via BSs, direct data exchanges among users, known as deviceto- device (D2D) communications, have consequently emerged as the most crucial innovation and the mandatory technology for a public safety network. However, due to the tight schedule for standardization, a special form of broadcasting communications has been adopted by D2D communications in Release 12. To fully comprehend such an unprecedented technology in cellular networks, this article provides a comprehensive overview of D2D operations in Release 12. From the system architecture to the radio interface, the provided insights boost the knowledge to practice D2D communications over cellular networks.

Toward moving public safety networks

Fourth generation LTE has been selected by U.S. federal and EU authorities to be the technology for public safety networks that would allow first responders to seamlessly communicate between agencies and across geographical locations in tactical and emergency scenarios. From Release 11 on, 3GPP has been developing and specifying dedicated nationwide public safety broadband networks that will be scalable, robust, and resilient, and can address the specific communication needs of emergency services. In this realm, the requirements and scenarios for isolated E-UTRAN with no or limited backhaul access to the core network are still in progress. In this article, we survey possible public safety use cases with the induced network topologies, discuss the current status of the 3GPP standards, and highlight future challenges. We further elaborate on the need to support mobile backhauling in moving-cell scenarios and describe two LTEbased solutions to enable dynamic meshing among the base stations.

Critical communications and public safety networks part 1: Standards, spectrum policy, and economics

Public safety networks have been utilized by first responder agencies in emergency situations, such as police officers, firefighters, and ambulances. Critical communications networks have been used in various sectors such as construction, transportation, utilities, factories, and mining operations.

Next generation public safety networks: A spectrum sharing approach

Wireless communications play a critical role in national security and disaster relief and are extensively utilized by first responder teams, such as police officers, firefighters, and ambulances. The first responders in emergency situations need to always be connected with one another and with the remote service centers for effective cooperation and coordination. However, the existing public safety (PS) services fail to satisfy the PS user requirements in many emergency scenarios, which usually leads to exceptionally high traffic loads. As a result, increasing the network capacity is one of the primary concerns, and spectrum sharing has been deemed the key solution. With appropriate spectrum sharing partnerships among PS agencies and commercial networks, PS users can access licensed PS spectrum, shared spectrum, as well as commercial networks when the need arises. In this article we present different initiatives undertaken by Wireless @ Virginia Tech toward the next generation PS network. We also discuss our vision of a flexible, rapidly deployable, and reconfigurable PS system to meet imminent and future demands on critical communications infrastructure and discuss the value of spectrum sharing for supporting this long-term vision.

Enabling Device to Device Broadcast for LTE Cellular Networks

In recent years, the public safety community has been aligning behind Long Term Evolution (LTE) technology as the basis for next generation public safety networks. Correspondingly, the 3rd Generation Partnership Project (3GPP) standards body has started multiple technical work initiatives on LTE enhancements to better support public safety use cases and requirements. Of particular importance to the public safety community is the addition of direct device-to-device (D2D) broadcast capability that can enable off-network push-to-talk (PTT) group communications in a manner equivalent to existing public safety communication systems. In this paper, we briefly explore the design objectives for, and challenges associated with, providing a D2D broadcast service. We then present and analyze a new distributed media access control (MAC) scheme for interference-aware coordination of both unicast and broadcast transmission. System-level simulation results are provided to validate the performance and the effectiveness of our approach, using a CSMA-based approach as a basis for comparison.

An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than of the theoretical optimal throughput and of fairness index especially in dynamic and dense networks.

How and why network governance evolves: evidence from a public safety network

Public sector organizations increasingly form interorganizational networks that rely on technology to achieve what they cannot achieve independently. The governance of these public sector networks is complex due to the nature of interorganizational relationships and technology. This paper aims to increase our understanding of network governance by exploring the evolution of governance over the 40+ year lifespan of a public sector network. The historical case study is based on the technology affordance and organizational actualization concepts applied to three critical incidents in the history of a public safety network. The incidents provide evidence that technology and governance do interact, that timing matters and that future research is needed to understand more fully how and why network governance evolves and the implications of governance evolution on network performance.

Profiling of Radio Propagation in VHF Band

The Very high frequency (VHF) band spans from 30 MHz to 300 MHz and is designated for public safety and disaster relief networks, FM radio broadcasting, TV broadcasting, air traffic control and many other mission critical services.  Most of these services often utilize the lower part of the VHF band and the coverage areas of such systems could be above hundreds of kilometers, which may require several transmitters operating in a quasi-synchronous mode. In addition, frequency reuse within this band for example, in the case of FM radio could result in excessive boarder area interference. Therefore, to minimize interference, even with the coexistence of these systems, there is a need to examine the behaviour of radio wave propagation in the band. Radio propagation models have been used extensively in interference analysis, coverage prediction and optimization. Most of the widely used models are location dependent, which, therefore, calls for continued efforts to ensure that location specific measurements are taken and used as planning tools, towards understanding the limitations arising from specific environmental conditions. In this work, Electromagnetic field (EM) strength measurements  were  conducted in Ilorin (Long 4o 36’ 25”E, Lat 8o 25’ 55’’N) and its environs within Kwara State, Nigeria, along some predefined routes, using dedicated Agilent N943C 100 Hz - 7 GHz spectrum analyzer. For each route, the measured received signal levels (RSLs) were obtained, profiled over the terrain and compared with simulated signal values obtained for COST 231, Egli, Hata and ILORIN models. A total of three transmitters were utilized; two in the lower VHF (LVHF) and one in the upper VHF (UVHF) bands. Results obtained showed that there is severe fading along all the routes considered, for all the broadcasting stations, with the highest signal level estimation observed for Egli, followed by COST 231, Hata and ILORIN model in that order. Measurements results also indicate that the received signal level is found to follow the terrain elevation for the models considered. However, the ILORIN model, which is a localized model was found to provide better predictions, despite the fact that the signal follows the terrain profile.