# Resource Allocation of UAV-Assisted IoT Node Secure Communication System

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## Abstract

**:**

## 1. Introduction

## 2. System Model and Problem Formulation

#### 2.1. System Model

#### 2.2. Problem Formulation

## 3. Proposed Optimization Algorithm

**Lemma**

**1.**

#### 3.1. Optimal Transmit Power of UAV

**Q**and PSR, the UAV transmit power optimization problem ${P}_{1.1}$ is given as

#### 3.2. Optimal UAV Trajectory

#### 3.3. Optimal Power Splitting Ratio

#### 3.4. Overall Algorithm

Algorithm 1 Alternative optimization algorithm for P_{1.1} |

1. Setting:T, N, ${E}_{min},{E}_{sen},{V}_{max},{P}_{max},{\mathbf{q}}_{0},{\mathbf{q}}_{F}$, and the tolerance error $\u03f5$ 2. Initialization:The iteration index $m=1$, ${\mathbf{q}}^{m}\left[n\right]$. 3. Repeat:3.1. Calculate ${p}^{opt}\left[n\right]$ according to (12) with the given ${\mathbf{q}}^{m}\left[n\right],\xi \left[n\right]$. Update $\mathsf{\mu}$, $\omega $, ${f}_{k}$, ${\lambda}_{k}$ by the subgradient algorithm3.2. Calculate ${\xi}^{opt}\left[n\right]$ according to (19) with the given ${\mathbf{q}}^{m}\left[n\right],{p}^{opt}\left[n\right]$. Update ${l}_{k},v$ and ${m}_{k}$ by the subgradient algorithm3.3. Solve P3 by CVX with given ${p}^{opt}\left[n\right]$ and ${\xi}^{opt}\left[n\right]$if $\sum m-\sum m-1\le \u03f5$ where $\sum m={\sum}_{n=1}^{N}\tau \left[n\right]$ Break; else Update the iterative number m = m + 1; End if Until $\sum m-\sum m-1\le \u03f5$ 4. Obtain solutions: ${p}^{opt}\left[n\right]$, ${\xi}^{opt}\left[n\right]$ and ${\mathbf{q}}^{opt}\left[n\right]$ |

_{4}is solved optimally with solution ${\mathbf{P}}^{m+1}$, ${\Xi}^{m+1}$, and (b) holds since the objective value of ${P}_{4}$ is the lower bound of the original problem. Based on (22)–(25), we can obtain that

## 4. Simulation Results and Numerical Analysis

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 2.**Trajectories of a UAV with a different location of $ENs$. H = 5.0 m, ${P}_{max}$ = 2 W. The coordinates of the UAV’s initial and final location are set as ${q}_{i}$ = (0, 10) and ${q}_{F}$ = (20, 10).

**Figure 4.**The harvesting energy versus the time slot. H = 5.0 m. The coordinates for $EN1$, $EN2$, and $DN$ are (5, 9), (15, 9), and (10, 15), respectively.

Parameters | Values [10] |
---|---|

Mission time T | 20 s |

Time slots N | 40 |

Maximum transmit power ${P}_{max}$ | 2 W |

Average transmission power $\overline{P}$ | $0.5$ W |

Noise power ${\delta}^{2}$ | −50 dBm |

Channel power gain $\overline{\beta}$ | −30 dBm |

Power conversion efficiency factor $\eta $ | $0.5$ |

Collecting energy threshold ${E}_{min}$ | 70 $\mathsf{\mu}$W |

Information coding threshold ${E}_{sen}$ | 50 $\mathsf{\mu}$W |

Maximum speed of UAV ${V}_{max}$ | 5 m/s |

Indices | Baseline [10] | Proposed Optimal Method |
---|---|---|

Maximum transmit power W | 0.5984 | 0.6207 |

Stable harvesting energy of $DN$ (W) | 1.176 × ${10}^{-5}$ | 7.322 × ${10}^{-6}$ |

Stable harvesting energy of $EN1$, $EN2$ (W) | 3.171 × ${10}^{-6}$ | 1.867 × ${10}^{-6}$ |

Maximum $DN$ and $ENs$ receive energy ratio | 1.8547 | 1.9612 |

Maximum instantaneous secrecy rate (bits/s/Hz) | 4.292 | 4.747 |

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**MDPI and ACS Style**

Ma, B.; Xu, D.; Ren, X.; Wang, Y.; Liu, J.
Resource Allocation of UAV-Assisted IoT Node Secure Communication System. *Signals* **2023**, *4*, 591-603.
https://doi.org/10.3390/signals4030031

**AMA Style**

Ma B, Xu D, Ren X, Wang Y, Liu J.
Resource Allocation of UAV-Assisted IoT Node Secure Communication System. *Signals*. 2023; 4(3):591-603.
https://doi.org/10.3390/signals4030031

**Chicago/Turabian Style**

Ma, Biyun, Diyuan Xu, Xinyu Ren, Yide Wang, and Jiaojiao Liu.
2023. "Resource Allocation of UAV-Assisted IoT Node Secure Communication System" *Signals* 4, no. 3: 591-603.
https://doi.org/10.3390/signals4030031