Abstract
In mobile ad hoc networks (MANETs), asset-task assignment problems have been explored with vastly different approaches. Considering the unique characteristics of MANET environments, such as no centralized trusted entity, a lack of resources, and high-security vulnerabilities, resource allocation is not a trivial problem particularly for situations where a mobile team aims to successfully complete a common mission. The existing approaches have studied asset-task assignment problems by best matching a node's functionality and requirements of a given task. In this paper, we propose a task assignment protocol using the concept of multidimensional trust, namely, CompoSite Trust-based Assignment (COSTA), aiming to maximize the completion ratio of a common mission consisting of multiple tasks by balancing trust and risk in executing them. Based on the core concept of trust defined as the willingness to take the risk in performing a given task, COSTA selects qualified nodes for a given task while meeting an acceptable risk level for executing multiple tasks contributing to successful mission completion. Given a mission consisting of dynamic multiple tasks, we model each task with importance, urgency, and difficulty characteristics and use them for selecting qualified members. In addition, we model a node's risk behavior (i.e., risk-seeking, risk-neutral, and risk-averse) and investigate its impact on mission performance where a payoff is given for member selection and task execution. We formulate an optimization problem for the task assignment using integer linear programming (ILP). Our simulation results validated with ILP solutions demonstrate the existence of an optimal acceptable risk level that best balances trust and risk so as to maximize the mission completion ratio. We conduct a comprehensive comparative analysis and show that COSTA achieves a higher mission completion ratio while incurring a lower communication overhead compared with non-trust-based counterparts.
Highlights
In tactical or service-oriented mobile ad-hoc networks (MANETs), a common mission is often assigned where it has multiple tasks
A mission team is considered where the team is composed of different entities responsible for completing respective tasks to pursue a common mission in the tactical MANET environment
IDm is the identifier (ID) of task m, Lm is the location of the task leader, Im is the importance level, NTmmin is the minimum required node type, Nmmin and Nmmax are the minimum and maximum numbers of member nodes, execution timeframe (ETm) refers to the start and end time of task m, and Wm is a maximum workload required per time unit for each member to perform task m
Summary
In tactical or service-oriented mobile ad-hoc networks (MANETs), a common mission is often assigned where it has multiple tasks. In [24], they further investigated a similar model for mobile offloading but for mobile social platforms with the aim to balance data bidders and increase the income per unit time for sellers Their works [23], [24] didn’t consider mission-oriented tactical environment requiring a level of trust and security to ensure mission completion under hostility. While the above works [20]–[27] tackled different, important aspects for a mission-oriented task allocation in MANETs, none of the above provide a holistic solution for such a system based on the concept of trust Unlike these works, our work considers trust and risk, and explores the trade-off between them for an optimal task assignment.
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