Abstract

In this paper, we consider a novel Internet of Things (IoT) system in smart city called unmanned aerial vehicle‐ (UAV‐) assisted cognitive backscatter network, where a UAV is employed as both a relay and a radio frequency source to help the data transmission between ground IoT backscatter devices (BDs) and a remote data center (DC). However, since the IoT applications are usually not assigned dedicated spectrum resource in smart cities, these data transmissions from BDs to the DC should share the licensed spectrum of cellular users (CUs). Therefore, we aim to maximize the minimum uplink throughput among all BDs while avoiding severe interference to CUs via joint spectrum management and UAV trajectory design. To solve the problem, we propose an iterative method utilizing block coordinated decent to partition the variables into two blocks. For the spectrum management problem, we first prove its convexity with the transmit power and time scheduling and then propose a two‐step method to solve the two variables sequentially. For the UAV trajectory design problem, we resort to the fractional programming method to handle it. Simulation results demonstrate that the proposed algorithm can significantly increase the average max‐min rate of the BDs while guaranteeing the acceptable interference to CUs with a fast convergence speed.

Highlights

  • The Internet of Things (IoT) is one of the most important application scenarios for the fifth-generation (5G) wireless communications

  • We summarize the proposed iterative algorithm as Algorithm 2, which handles joint time scheduling, transmit power control, and unmanned aerial vehicles (UAVs) trajectory design based on the block coordinated decent (BCD) and fractional programming (FP) methods

  • We consider a unmanned aerial vehicle- (UAV-)assisted cognitive backscatter network as shown in Figure 3, where the data center (DC) is located in the cell center, and 5 backscatter devices (BDs) are randomly distributed within the area with the radius of 200 m

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Summary

Introduction

The Internet of Things (IoT) is one of the most important application scenarios for the fifth-generation (5G) wireless communications. It enables different smart devices to connect with each other via wireless networks, has a great potential to remould vertical industries such as manufacturing, agriculture, urban-construction, and transportation [1, 2]. Since the IoT allows massive devices to access wireless networks, it faces various practical challenges in its deployment [3]. The IoT devices are usually too small to equip with high-capacity batteries. Massive deployed IoT devices may exacerbate spectrum scarcity problems [4]. Future widespread IoT applications highly require energy- and spectrum-efficient wireless communications techniques [5, 6]

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