Abstract
This paper considers Low Earth Orbit (LEO) satellite- and cache-assisted unmanned aerial vehicle (UAV) communications for content delivery in terrestrial networks, which shows great potential for next-generation systems to provide ubiquitous connectivity and high capacity. Specifically, caching is provided by the UAV to reduce backhaul congestion, and the LEO satellite supports the UAV’s backhaul link. In this context, we aim to maximize the minimum achievable throughput per ground user (GU) by jointly optimizing cache placement, the UAV’s resource allocation, and trajectory while cache capacity and flight time are limited. The formulated problem is challenging to solve directly due to its non-convexity and combinatorial nature. To find a solution, the problem is decomposed into three sub-problems: (1) cache placement optimization with fixed UAV resources and trajectory, followed by (2) the UAV resources optimization with fixed cache placement vector and trajectory, and finally, (3) we optimize the UAV trajectory with fixed cache placement and UAV resources. Based on the solutions of sub-problems, an efficient alternating algorithm is proposed utilizing the block coordinate descent (BCD) and successive convex approximation (SCA) methods. Simulation results show that the max-min throughput and total achievable throughput enhancement can be achieved by applying our proposed algorithm instead of other benchmark schemes.
Highlights
Fifth-generation (5G) wireless systems are being deployed around the world [1], the explosive growth of mobile data traffic still poses significant challenges for future networks, i.e., beyond 5G or sixth-generation (6G)
Satellites are installed in geostationary earth orbit (GEO), medium earth orbit (MEO), and/or low earth orbit (LEO), which can complement and support terrestrial communication networks
Our work proposes a novel system model in satellite- and cache-assisted unmanned aerial vehicle (UAV) wireless networks that further explores the impact of data transmission latency for backhaul link from satellite-to-UAV due to large distance and limited resource allocation, which makes the problem design even more challenging to solve and has not been investigated before
Summary
Fifth-generation (5G) wireless systems are being deployed around the world [1], the explosive growth of mobile data traffic still poses significant challenges for future networks, i.e., beyond 5G or sixth-generation (6G). Aimed to minimize the total energy consumption of GEO satellite and UAV but did not solve the problem of maximizing the minimum throughput of GUs. In [27], the authors investigated a satellite-UAV mobile edge caching system in Internet-of-Things (IoT) networks, where they considered limited storage capacity for the IoT users but not as a caching model for content-based networks. This work considers that the UAV can serve multiple GUs simultaneously to improve network performance, i.e., max-min throughput Motivated by these observations, our work proposes a novel system model in satellite- and cache-assisted UAV wireless networks that further explores the impact of data transmission latency for backhaul link from satellite-to-UAV due to large distance and limited resource allocation, which makes the problem design even more challenging to solve and has not been investigated before. E[x] denotes the expected value of x. x and x define a ceiling and nearest integer function of a number x, respectively
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