# Opportunistic DF-AF Selection Relaying in Hybrid Wireless and Power Line Communication for Indoor IoT Networks

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## Abstract

**:**

## 1. Introduction

- The $ST\mathcal{P}$ for the direct link and ODF-AF relay-aided links of the dual-hop HD EH HWP over log-normal fading channels is analytically expressed.
- The $ST\mathcal{P}$ and throughput performance of the ODF-AF selection relaying scheme in the HWP are analyzed and validated with Monte Carlo simulation results.

## 2. System Model

**Remark**

**1.**

**Remark**

**2.**

## 3. Performance Analysis

#### 3.1. Opportunistic Decode-and-Forward (ODF) Relaying Scheme

**Theorem**

**1.**

**Proof.**

#### 3.2. Opportunistic Amplify-and-Forward (OAF) Relaying Scheme

**Theorem**

**2.**

**Proof.**

#### 3.3. Opportunistic Decode-and-Forward and Amplify-and-Forward (ODF-AF) Relaying Scheme

#### 3.4. Throughput Performance

## 4. Numerical Results and Discussion

**${\chi}_{k}=0.4$**and has remarkably raised from 0.07 to approximately 0.67. This means that up to 40% of the power transmission ${P}_{S}=1$ (dB) can be allocated to the EH module to obtain the optimized performance. Indeed, the power transmission values used in Figure 2 and Figure 3 are rather small, −10 (dB) and 1 (dB). Given that the input power can be set to a higher value, the $ST\mathcal{P}$ could accordingly raise to its maximum.

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

5G | Fifth generation of cellular networks |

EH | Energy harvesting |

RF | Radio frequency |

SWIPT | Simultaneous wireless information and power transfer |

PLC | Power line communication |

SG | Smart grids |

IoT | Internet of Things |

HWP | Hybrid wireless and power line communication |

EE | Energy efficiency |

SE | Spectrum efficiency |

PT | Power transmission |

PS | Power splitting |

PSR | Power splitting-based relaying |

TSR | Time splitting-based relaying |

(O)DF | (Opportunistic) decode-and-forward |

(O)AF | (Opportunistic) amplify-and-forward |

ODF-AF | Opportunistic DF-AF |

HD | Half-duplex |

FD | Full-duplex |

RS | Relay selection |

SDP | Signal decision processor |

SNR | Signal-to-noise ratio |

CSI | Channel state information |

AWGN | Additive white Gaussian noise |

i.i.d. | independently and identically distributed |

Probability density function | |

CDF | Cumulative distribution function |

$\mathcal{OP}$ | Outage probability |

$ST\mathcal{P}$ | Successful transmission probability |

ACK | Acknowledgement signal |

RV | Random variable |

TDMA | Time division multiple access |

SC | Selection combining |

S | The source node |

D | The destination node |

${R}_{i}$ | The i-th relay of K relays, ($1\le i\le K$) |

X, Y, Z | The channel coefficients of S–${R}_{i}$, ${R}_{i}$–D, S–D links |

${\left|X\right|}^{2}$, ${\left|Y\right|}^{2}$ and ${\left|Z\right|}^{2}$ | The i.i.d. log-normal RVs with $LN\left(\right)open="("\; close=")">2{\omega}_{X},4{\Omega}_{X}^{2}$, $LN\left(\right)open="("\; close=")">2{\omega}_{Y},4{\Omega}_{Y}^{2}$ and $LN\left(\right)open="("\; close=")">2{\omega}_{Z},4{\Omega}_{Z}^{2}$ |

${\omega}_{j}$, ${\Omega}_{j}^{2}$ | The mean and the standard deviation of $10{log}_{10}\left(j\right),j\in \{X;Y;Z\}$ |

${d}_{X}$, ${d}_{Y}$, ${d}_{Z}$ | The S–${R}_{i}$, ${R}_{i}$–D, S–D distances |

${P}_{S}$ | The power of S |

${P}_{{R}_{i}}$ | The energy of i-th R |

${n}_{j}$ | Additive white Gaussian noise (AWGN), ($j\in \left(\right)open="\{"\; close="\}">{r}_{k},d$) |

${N}_{0}$ | The zero mean and variance at the i-th R and D |

${\chi}_{i}$ | The decoding state of ODF-AF ${R}_{i}$, $i\in 1,\cdots ,K$ |

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**Figure 1.**A typical HWP system with relaying nodes having both wireless and PLC interfaces. The relays scatter on different floors and rooms, and PLC relays are installed in electrical devices, which are connected with the power line.

**Figure 6.**$ST\mathcal{P}$ versus SNR with two different threshold values ${R}_{0}=1$ and ${R}_{0}=2$ (bps/Hz).

**Figure 8.**$ST\mathcal{P}$ versus different S–R distance values, ${d}_{X}$, on condition that ${d}_{Z}=10$ (m), ${d}_{Y}={d}_{Z}-{d}_{X}$.

Primary Parameters | Description | Values |
---|---|---|

W | frequency bandwidth | 5 (W) |

${R}_{0}$ | transmission rate threshold | 1 (bps/Hz) |

${P}_{S}$ | traditional stabilized power source | −10 (dB) |

${N}_{0}$ | overall AWGNs | 1 |

$\eta $ | energy harvesting efficiency | 1 |

$\delta $ | power splitting fraction | 0.2 |

m | path-loss | 2.7 |

${d}_{X}$ | S to R distance | 1 (m) |

${d}_{Y}$ | R to D distance | 1 (m) |

${d}_{Z}$ | S to D distance | 2 (m) |

${\Omega}_{X}$ | S to R channel mean, log-normally distributed | 4 (dB) |

${\Omega}_{Y}$ | Rto D channel mean, log-normally distributed | 4 (dB) |

${\Omega}_{Z}$ | S to D channel mean, log-normally distributed | 4 (dB) |

${\omega}_{X}$ | S to R channel variance, log-normally distributed | 3 (dB) |

${\omega}_{Y}$ | R to D channel variance, log-normally distributed | 3 (dB) |

${\omega}_{Z}$ | S to D channel variance, log-normally distributed | 3 (dB) |

K | Number of relays | 3 |

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## Share and Cite

**MDPI and ACS Style**

Van, H.T.; Van, Q.-N.; Le, D.H.; Van, H.-P.; Jalowiczor, J.; Nguyen, H.-S.; Voznak, M.
Opportunistic DF-AF Selection Relaying in Hybrid Wireless and Power Line Communication for Indoor IoT Networks. *Sensors* **2021**, *21*, 5469.
https://doi.org/10.3390/s21165469

**AMA Style**

Van HT, Van Q-N, Le DH, Van H-P, Jalowiczor J, Nguyen H-S, Voznak M.
Opportunistic DF-AF Selection Relaying in Hybrid Wireless and Power Line Communication for Indoor IoT Networks. *Sensors*. 2021; 21(16):5469.
https://doi.org/10.3390/s21165469

**Chicago/Turabian Style**

Van, Hoang Thien, Quyet-Nguyen Van, Danh Hong Le, Hoang-Phuong Van, Jakub Jalowiczor, Hoang-Sy Nguyen, and Miroslav Voznak.
2021. "Opportunistic DF-AF Selection Relaying in Hybrid Wireless and Power Line Communication for Indoor IoT Networks" *Sensors* 21, no. 16: 5469.
https://doi.org/10.3390/s21165469