Abstract
Currently, deploying fixed terrestrial infrastructures is not cost-effective in temporary circumstances, such as natural disasters, hotspots, and so on. Thus, we consider a system of caching-based UAV-assisted communications between multiple ground users (GUs) and a local station (LS). Specifically, a UAV is exploited to cache data from the LS and then serve GUs’ requests to handle the issue of unavailable or damaged links from the LS to the GUs. The UAV can harvest solar energy for its operation. We investigate joint cache scheduling and power allocation schemes by using the non-orthogonal multiple access (NOMA) technique to maximize the long-term downlink rate. Two scenarios for the network are taken into account. In the first, the harvested energy distribution of the GUs is assumed to be known, and we propose a partially observable Markov decision process framework such that the UAV can allocate optimal transmission power for each GU based on proper content caching over each flight period. In the second scenario where the UAV does not know the environment’s dynamics in advance, an actor-critic-based scheme is proposed to achieve a solution by learning with a dynamic environment. Afterwards, the simulation results verify the effectiveness of the proposed methods, compared to baseline approaches.
Highlights
Wireless communication has been evolving for high throughput, and for ultra-reliability, efficient energy consumption, and to support highly diversified applications with heterogeneous requirements for quality of service (QoS) [1]
We aim to optimize the transmission power allocated to the GUs and the content caching by unmanned aerial vehicles (UAVs) F such that the sum cumulative data rate of ground users can be maximized in a long-term operation
We present the numerical simulation results regarding the performance of the two proposed schemes and those of other benchmark schemes based on the Myopicmethod [48]: a Myopic-non-orthogonal multiple access (NOMA) scheme, a Myopic-NOMA-RCscheme, and a Myopic-orthogonal multiple access (OMA) scheme
Summary
Wireless communication has been evolving for high throughput, and for ultra-reliability, efficient energy consumption, and to support highly diversified applications with heterogeneous requirements for quality of service (QoS) [1]. To this end, extensive research efforts have mainly been devoted to fixed terrestrial infrastructures such as ground base stations (BSs), access points, and relays, which generally restrict their capability to cost-effectively meet the ever-increasing multifarious traffic demand. By leveraging low-altitude UAVs (i.e., less than about one kilometer above the ground [5]), the wireless communication system can provide swift deployment and high flexibility in mobility [2]. The UAV can provide additional aid as either a stand-alone aerial BS [4,8], or it can serve as a part of a heterogeneous network in a multi-tier
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