LAPS-and-D2D Enabled Maritime Emergency Communications: Deployment Optimization and Resource Management

This paper investigates the application of low altitude platform station (LAPS) and device-to-device (D2D) techniques in maritime emergency communications. The hovering LAPS acts as an aerial base station to provide emergency telecommunications services, and the D2D technique is used to improve spectrum utilization. To make full use of the advantages of LAPS-and-D2D enabled networks, we formulate a sum rate maximization problem by jointly considering the deployment optimization and resource management (DORM). The formulated problem is constrained by the reliability and minimum capacity requirements. To solve this problem, an iterative optimization algorithm (IOA) is designed. First, by using the graphical method, the closed-form solution of optimal power allocation is derived. Next, we transform the spectrum reuse problem into a min-cost max-flow problem, and the Ford-Fulkerson algorithm is employed to solve it. Then, we present a meta-heuristic algorithm to optimize the LAPS deployment. Finally, the simulation results indicate that the proposed DORM scheme outperforms the state-of-the-art works in term of the sum rate. In addition, the convergence and performance gap of the designed IOA are demonstrated.

I. Introduction

In the oceans, it is challenging to achieve maritime emergency communications (ECs), especially when emergency telecommunications services cannot be provided through fixed infrastructures, e.g., satellites and on-shore base stations (BSs) [1]. Facing this challenge, it is a promising approach to adopt the low altitude platform station (LAPS) with flexible deployment and timely response as an aerial BS to support maritime ECs [2]. Meanwhile, considering the harsh maritime environments and the limitations of full-service access capability, the device-to-device (D2D) technique can be applied in maritime ECs to improve spatial reuse by performing local data exchange [3]. Specifically, using the D2D communication can establish a communication link directly between unmanned surface vessels (USVs) without the need for traditional BSs or central nodes [4]. In the event of maritime disasters, the BSs may be damaged or the communication may be interrupted. In this situation, we can adopt the D2D techniques to ensure independent communication connection and improve the reliability and stability of ECs. In addition, considering the complex maritime environments and shortage of electricity and fuel supplies, the maritime network for ECs should be energy-efficient [5]. Compared with the satellite-BS-USV transmissions, the D2D-enabled transmissions reduce the energy consumption required for transmission through remote BSs and satellites.