Post-disaster Communications Research Articles

Emergency communications after earthquake reveal social network backbone of important ties.

Social networks provide a basis for collective resilience to disasters. Combining the quasi-experimental context of a major earthquake in Ya'an, China, with anonymized mobile telecommunications records regarding 91,839 Ya'an residents, we use initial bursts of postdisaster communications (e.g. choice of alter, order of calls, and latency) to reveal the "important ties" that form the social network backbone. We find that only 26.8% of important ties activated during the earthquake were the strongest ties during normal times. Many important ties were hitherto latent and weak, only to become persistent and strong after the earthquake. We show that which ties activated during a sudden disaster are best predicted by the interaction of embeddedness and tie strength. Moreover, a backbone of important ties alone (without the inclusion of weak ties ordinarily seen as important to bridge communities) is sufficient to generate a hierarchical structure of social networks that connect a disaster zone's disparate communities.

Mobility-Aware Resource Allocation in IoRT Network for Post-Disaster Communications with Parameterized Reinforcement Learning.

Natural disasters, including earthquakes, floods, landslides, tsunamis, wildfires, and hurricanes, have become more common in recent years due to rapid climate change. For Post-Disaster Management (PDM), authorities deploy various types of user equipment (UE) for the search and rescue operation, for example, search and rescue robots, drones, medical robots, smartphones, etc., via the Internet of Robotic Things (IoRT) supported by cellular 4G/LTE/5G and beyond or other wireless technologies. For uninterrupted communication services, movable and deployable resource units (MDRUs) have been utilized where the base stations are damaged due to the disaster. In addition, power optimization of the networks by satisfying the quality of service (QoS) of each UE is a crucial challenge because of the electricity crisis after the disaster. In order to optimize the energy efficiency, UE throughput, and serving cell (SC) throughput by considering the stationary as well as movable UE without knowing the environmental priori knowledge in MDRUs aided two-tier heterogeneous networks (HetsNets) of IoRT, the optimization problem has been formulated based on emitting power allocation and user association combinedly in this article. This optimization problem is nonconvex and NP-hard where parameterized (discrete: user association and continuous: power allocation) action space is deployed. The new model-free hybrid action space-based algorithm called multi-pass deep Q network (MP-DQN) is developed to optimize this complex problem. Simulations results demonstrate that the proposed MP-DQN outperforms the parameterized deep Q network (P-DQN) approach, which is well known for solving parameterized action space, DQN, as well as traditional algorithms in terms of reward, average energy efficiency, UE throughput, and SC throughput for motionless as well as moveable UE.

Cooperative aerial and ground vehicle trajectory planning for post-disaster communications: An attention-based learning approach

The ground infrastructures are highly susceptible to disruption after disasters, which causes the paralysis of communication. In this case, solutions besides original architecture are needed to meet the requirements of communication. Since unmanned aerial vehicle (UAV) can be quickly sent to disaster events to provide temporary connection due to its agility and mobility, it is suitable for performing disaster relief. Nevertheless, the limited onboard energy restricts the UAVs from fulfilling such persistent tasks. To this end, we introduce a ground vehicle carrying backup batteries to handle the energy issue of the UAV. Considering a time-constrained disaster-affected area, we propose a cooperative trajectory planning scheme to provide emergency communications swiftly and timely. The goal of our optimization task is to minimize the total cost of the mission, which consists of the operation cost for mission completion and the penalty cost for latency. We show that the task can be regarded as an extension of traveling salesman problem with soft time window constraints, which is NP-hard in general, and we propose a novel attention-based deep reinforcement learning with a sequential model strategy to learn the policy for the UAV's visiting order, based on which the trajectories of the UAV and ground vehicle are jointly designed. Numerical results show that our proposed attention-based trajectory planning scheme is effective and efficient, providing a guideline for the system design of post-disaster communications.

Post-Disaster Communications: Enabling Technologies, Architectures, and Open Challenges

The number of disasters has increased over the past decade where these calamities significantly affect the functionality of communication networks. In the context of 6G, airborne and spaceborne networks offer hope in disaster recovery to serve the underserved and to be resilient in calamities. Therefore, our paper reviews the state-of-the-art literature on post-disaster wireless communication networks and provides insights for the future establishment of such networks. In particular, we first give an overview of the works investigating the general procedures and strategies for facing any large-scale disaster. Then, we present technological solutions for post-disaster communications, such as the recovery of the terrestrial infrastructure, installing aerial networks, and using spaceborne networks. Afterwards, we shed light on the technological aspects of post-disaster networks, primarily the physical and networking issues. We present the literature on channel modeling, coverage and capacity, radio resource management, localization, and energy efficiency in the physical layer part, and discuss the integrated space-air-ground architectures, routing, delay-tolerant/software-defined networks, and edge computing in the networking layer part. This paper also includes interesting simulation results which can provide practical guidelines about the deployment of ad hoc network architectures in emergency scenarios. Finally, we present several promising research directions, namely backhauling, cache-enabled and intelligent reflective surface-enabled networks, placement optimization of aerial base stations (ABSs), and the mobility-related aspects that come into play when deploying aerial networks, such as planning their trajectories and the consequent handovers (HOs).

Cooperative Aerial and Ground Vehicle Trajectory Planning for Post-Disaster Communications: An Attention-Based Learning Approach

Cooperative Aerial and Ground Vehicle Trajectory Planning for Post-Disaster Communications: An Attention-Based Learning Approach

On the Topological Aspects of UAV-Assisted Post-Disaster Wireless Communication Networks

In the context of sixth-generation (6G) networks, emergency management systems based on wireless communications have recently gained increasing interest. Hereby, fundamentals and open problems of post-disaster communications are discussed, especially focusing on their topological aspects. The motivation behind this choice is that whenever a natural or man-made disaster occurs, there is a high chance that the terrestrial communication infrastructure is compromised, and therefore alternative networks need to be deployed efficiently in order to enable the majority of the civilians and first responders to communicate. In this article, we first provide a brief review of existing aerial ad hoc networks for post-disaster communications. Next, we shed light on some new aspects of this problem, which are related to the topology of the network supporting the impacted area. Finally, with the aid of selected simulation results, we show how the cellular infrastructure requirements for a disaster-struck region significantly depend on its location and extension.

An Efficient Energy Harvesting and Optimal Clustering Technique for Sustainable Postdisaster Emergency Communication Systems

The energy consumption and coverage range of unmanned aerial vehicles (UAVs) are major challenges in UAV-based postdisaster communications. To address these challenges, energy harvesting is employed to power communication devices and prolong the lifetime of the wireless communication network during a disaster. In addition, clustering techniques and device-to-device (D2D) communication are needed to increase the overall network coverage and provide sustainable connectivity during the disaster and postdisaster phases. We have proposed a novel emergency communication system (ECS) using the optimal cluster head (CH) technique to improve the energy transfer efficiency for sustainable network connectivity. We have developed a UAV deployment model assisted by the clustering technique and D2D links that is capable of harvesting energy to increase the network lifetime. This new approach is expected to enhance the reliability of the network in disaster situations. The proposed methods have been evaluated by measuring the energy efficiency performance and the network outage probability. The simulation results demonstrate improved performance with the deployment of optimal CHs, while the outage probability has been effectively reduced. Moreover, the proposed approach has been proven to reduce the computational complexity. In conclusion, UAV deployment with the optimal CH algorithm is a suitable network design to recover from natural disasters and potentially save many lives.

The Effectiveness of Post-Disaster Recovery Marketing Messages—The Case of the 2009 Australian Bushfires

ABSTRACT An understanding of how best to communicate with the tourism market in the wake of a disastrous event is essential for destination marketing organizations seeking to manage the misperceptions and media-imposed attitudes held by potential visitors. To date, the literature remains silent in terms of the types of messages destination marketing organizations are best to employ when a disaster has hit and consequently marketers often take an “ad hoc” approach to their post-disaster communications that may or may not be effective in terms of encouraging visitation. In response to this knowledge gap, the research presented in this article adopted an experimental methodology to examine the effectiveness of nine disaster recovery message themes commonly used by destination marketing organizations. The messages were presented to respondents via a print advertisement promoting the Victorian region of Gippsland—a tourism region severely affected by the 2009 Black Saturday Bushfires. The results revealed that a marketing message endorsed by a well-known and well-associated celebrity figure is likely to be most effective in encouraging tourists to return to or visit a disaster-affected destination 12 to 24 months following the event. The findings also revealed a significant relationship between past visitation and the time frame in which visitors will visit a disaster-affected region. Those who had visited the region four times or more were much more likely to return within 6 months of the event than less frequent visitors. A final important message revealed in this study was the fact that the tourism market is not averse to disaster recovery promotional activities, a concern often considered by destination marketers when planning their post-disaster recovery campaigns.

Web 2.0 for Disaster Response and Recovery

Successful disaster response is an exercise in managing human resources under very difficult conditions. Catastrophic disasters can disrupt both the physical communication networks and the social networks critical to efficient response and recovery. While a well-designed disaster plan serves as a framework, it often requires communication and collaboration between responders to adapt it to the situation at hand. Displacement of library staff adds to the chaotic nature of post-disaster communications, increasing the need for collaborative Web spaces to adapt to changing situations. Using case studies of catastrophic disaster response at libraries, this article begins with an analysis of human resource management problems common to disaster response coordinators worldwide. It then discusses Auburn University Libraries’ uses of free Web 2.0 applications in support of library disaster preparation, response, and recovery. While Auburn University's location on the coastal plain of Alabama is vulnerable to both hurricanes and tornadoes, Auburn has so far only needed to respond to small-scale disasters. The devastation suffered by libraries in the paths of Hurricanes Katrina and Rita served to propel Auburn toward a more comprehensive preparedness stance. Disaster planning at Auburn has embraced Web 2.0 applications, such as Google Documents and Google Talk, to introduce redundant communication channels and to allow for efficient collaboration regardless of the location of library responders. By identifying key Web 2.0 applications and properties that are useful for response and recovery efforts, the research in this article may assist other libraries in improving their disaster preparedness.

Cluster-based Communications System for Immediate Post-disaster Scenario

Communication facilities can totally be destroyed by natural and / or manmade disasters. A critical problem after disaster is getting the first hand knowledge of the destructions and also establishing some communication links among the survivors. This paper focuses on the vital need for providing communications facility to the victims, immediately after the disaster and prior to the arrival of rescue teams. The proposed novel approach in emergency communications enables survivors to communicate among themselves and help each other. Here, the idea of a selforganizing network is put forward, which makes use of available network resources formally occupied by the destroyed and / or damaged telecommunications’ infrastructure. In our post-disaster scenario, mobile nodes establish a self-organizing / ad hoc network which provides critical level of communications among disaster victims needed at that time and consequently tries to merge with some surviving telecommunications infrastructure and / or network deployed by rescue teams. The outcome of this paper is a fundamentally novel idea for immediate postdisaster communications. This idea is tested through some network survivability measures and hypothesis testing. We also test the working of this ad hoc network through simulation for post-disaster scenarios of partially and fully destroyed networks. The results obtained are found to be satisfactory and within acceptable limits of ad hoc networks.

Mobile Handsets as Sensing Nodes in an Auto-Configured Hierarchical Cognitive Radio Network Scheme for Immediate Post-Disaster Communications

A critical problem after a natural/manmade disaster is to provide immediate post-disaster communication links between the disaster victims and some overlay networks. This paper proposes a novel scheme that uses the surviving Mobile handSets (MS) as sensing nodes to form an auto-configured Hierarchical Cognitive Radio Network (H-CRN). The implementation of this H-CRN is explained through detailed problem scenario statement and step-by-step implementation of automatic identification of emergency situation by the MS nodes. An overview of the cross-layer framework used by the MS nodes is also presented. This novel scheme is tested through some hypothesis along with probability calculations for successful identification of emergency situation, formation of ad hoc group and Emergency Beacon Message (EBM) transmission.