I. Banerjee
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Scale choices shape species adaptation predictions
Improving conservation modeling under global change
This paper addresses the challenge of establishing a resilient disaster communication system that transitions seamlessly from a phone-based ad hoc network to any portable infrastructure and back. For this purpose, this paper presents a value-based design of an autonomous and self-organized protocol (SOS-hybrid). This design ensures seamless integration between various communication networks taking local context into account to increase inclusion and continuity of connectivity. SOS-hybrid has two benefits. First, local self-organization can adapt to the local situation in a disaster area. Second, context-awareness can fill in the spatial gaps of coverage associated with top-down approaches. An agent-based modelling approach was used to develop the simulation of the proposed communication network to evaluate the impact of introducing SOS-hybrid in the aftermath of a disaster. SOS-hybrid allows phones to simultaneously provide the benefits of (i) ad hoc mobile networking, allowing hard-to-reach people to connect, and (ii) infrastructure-based communication, allowing phones to more efficiently send messages over long distances. Benefits include two-way communication between community and rescue operators, inclusion and continued connectivity for immobile citizens stuck in isolated out of coverage areas, and seamless transition without loss of messages.
Participatory resilience of disaster-struck communities requires reliable communication for self-organized rescue, as conventional communication infrastructure is damaged. Disasters often lead to blackouts preventing citizens from charging their phones, leading to disparity in battery charges and a digital divide in communication opportunities. We propose a value-based emergency communication system based on participatory fairness, ensuring equal communication opportunities for all, regardless of inequality in battery charge. The proposed infrastructure-less emergency communication network automatically and dynamically (i) assigns high-battery phones as hubs, (ii) adapts the topology to changing battery charges, and (iii) self-organizes to remain robust and reliable when links fail or phones leave the network. The novelty of the proposed mobile protocol compared to mesh communication networks is demonstrated by comparative agent-based simulations. An evaluation using the Gini coefficient demonstrates that our network design results in fairer participation of all devices and a longer network lifetime, benefiting the community and its participants.
When physical communication network infrastructures fail, infrastructure-less communication networks such as mobile ad-hoc networks (MANET), can provide an alternative. This, however, requires MANETs to be adaptable to dynamic contexts characterized by the changing density and mobility of devices and availability of energy sources. To address this challenge, this paper proposes a decentralized context-adaptive topology control protocol. The protocol consists of three algorithms and uses preferential attachment based on the energy availability of devices to form a loop-free scale-free adaptive topology for an ad-hoc communication network. The proposed protocol has a number of advantages. First, it is adaptive to the environment, hence applicable in scenarios where the number of participating mobile devices and their availability of energy resources is always changing. Second, it is energy-efficient through changes in the topology. This means it can be flexibly combined with different routing protocols. Third, the protocol requires no changes on the hardware level. This means it can be implemented on all current phones, without any recalls or investments in hardware changes. The evaluation of the protocol in a simulated environment confirms the feasibility of creating and maintaining a self-adaptive ad-hoc communication network, consisting of multitudes of mobile devices for reliable communication in a dynamic context.
Disaster communication has made immense progress in the last thirty years. At present, disaster research focuses on bottom-up approaches such as civilian inclusion in disaster response. With the advent of smartphones, citizen-based emergency communication has become possible. Present ad hoc communication technologies typically form a fully connected mesh network, which connects all phones that are within each other's transmission range. This facilitates low-latency direct communication between citizens, but it quickly drains the battery of phones. Alternative ad hoc communication networks form an adaptive energy-efficient network topology, that is most draining to batteries of phones that have a higher charge, while low-energy phones are spared from relaying messages, thereby preserving battery and thus maintaining their connection with the rescue communication network. Both of these approaches have their own advantages. Which one is best for communication needs depends on the context. This position paper discusses the possibility of a decision model as an approach to automatically switch between the two alternative ad hoc communication networks. This ensures that citizens in disasters can make use of the optimal communication system at all times.