# Low-Power LoRa Signal-Based Outdoor Positioning Using Fingerprint Algorithm

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## Abstract

**:**

## 1. Introduction

## 2. Related Work

#### 2.1. RSSI Proximity and Path-Loss-Model-Based Positioning

#### 2.2. TDoA-Based Positioning

#### 2.3. Fingerprint-Algorithm-Based Positioning

## 3. Proposed Fingerprint Algorithm

#### 3.1. LoRa-Based Positioning

#### 3.2. LoRa Fingerprint Map Generation

#### 3.3. Probability Map Generation and Positioning

## 4. Experimental Results

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Telecommunication methods [2].

**Figure 2.**Comparison of positioning technologies [6].

**Figure 3.**Link budget calculation to measure RSSI values [2].

**Figure 4.**Semtech Corporation’s TDoA-based geolocation architecture [6].

**Figure 5.**Comparisons of packet flow between Wi-Fi and LoRa positioning methods: (

**a**) downlink packet from AP to smartphone and (

**b**) uplink packet from end-device to LoRa gateways.

**Figure 8.**Interpolation of f(x,y) using Gaussian RBF with 25 sample points: (

**a**) Random data points. (

**b**) the RBF centered at the collocation points (

**c**) shows the interpolated surface [21].

**Figure 9.**Comparison of interpolated fingerprint maps: (

**a**) cubic, (

**b**) Gaussian, (

**c**) quintic, (

**d**) linear, and (

**e**) thin plate interpolation methods.

**Figure 11.**Comparison of candidate regions. We filter candidate regions with 3 dBm. Dark areas represent candidates region with (

**a**) strong and (

**b**) weak RSSI signals.

**Figure 12.**Signal-strength distribution at a fixed location. [22].

**Table 1.**Average and Standard Deviation of Absolute Residual between interpolated and test value (dBm).

Gateway | Algorithm | AVG | STD | Gateway | Algorithm | AVG | STD |
---|---|---|---|---|---|---|---|

GW1 | cubic | 11.65 | 9.98 | GW3 | cubic | 5.12 | 6.44 |

Gaussian | 41.70 | 23.82 | Gaussian | 19.71 | 27.90 | ||

quintic | 14.75 | 5.55 | quintic | 7.27 | 10.49 | ||

linear | 7.03 | 1.60 | linear | 2.36 | 1.57 | ||

thin plate | 8.65 | 1.96 | thin plate | 3.32 | 2.95 | ||

GW2 | cubic | 3.11 | 2.45 | GW4 | cubic | 4.24 | 3.70 |

Gaussian | 19.61 | 23.82 | Gaussian | 29.69 | 59.20 | ||

quintic | 5.87 | 5.55 | quintic | 14.43 | 32.36 | ||

linear | 2.43 | 1.60 | linear | 2.52 | 1.78 | ||

thin plate | 2.44 | 1.96 | thin plate | 3.00 | 2.10 |

Point Number | Algorithm | Point Number | Algorithm | Point Number | Algorithm | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|

1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | |||

1 | 49.2 | 18.4 | 14.8 | 17 | 26.1 | 32.6 | 39.3 | 33 | 5.8 | 5.8 | 17.5 |

2 | 15 | 15 | 12.2 | 18 | 107.1 | 107.1 | 8 | 34 | 7.2 | 7.2 | 8.1 |

3 | 37.4 | 37.4 | 29.4 | 19 | 91.9 | 91.9 | 56.8 | 35 | 53.1 | 42.4 | 13 |

4 | 9.4 | 5.8 | 5.1 | 20 | 50.8 | 50.8 | 50.8 | 36 | 100.1 | 24.3 | 19 |

5 | 51.2 | 71.3 | 49.2 | 21 | 7.1 | 7.1 | 10.8 | 37 | 9.8 | 9.8 | 13.2 |

6 | 19.4 | 19.4 | 15.7 | 22 | 15.3 | 17 | 15 | 38 | 27 | 27 | 25 |

7 | 42.4 | 42.4 | 42 | 23 | 21 | 21 | 10.3 | 39 | 16.8 | 9.4 | 15.5 |

8 | 85.3 | 39.2 | 15 | 24 | 5 | 5 | 8.5 | 40 | 20.4 | 25.7 | 26.1 |

9 | 7.2 | 7.2 | 7.2 | 25 | 40.5 | 40.5 | 40.5 | 41 | 14.6 | 14.6 | 12.4 |

10 | 55.7 | 88.1 | 19.7 | 26 | 7.1 | 7.1 | 6.3 | 42 | 15.7 | 13.9 | 28.3 |

11 | 32 | 28.1 | 23.5 | 27 | 29.2 | 9.4 | 9.4 | 43 | 11.3 | 15.7 | 15.2 |

12 | 22.8 | 22.8 | 22.8 | 28 | 61.2 | 63.1 | 63.1 | 44 | 59.1 | 59.1 | 40.9 |

13 | 84 | 34.5 | 32.6 | 29 | 23.4 | 28 | 33 | 45 | 17.5 | 17.5 | 16 |

14 | 16 | 6.1 | 7.3 | 30 | 27.5 | 27.5 | 26.1 | 46 | 6.3 | 58.7 | 51 |

15 | 24.3 | 24.3 | 91.7 | 31 | 34.2 | 41.1 | 15.3 | AVG | 32.5 | 29.8 | 24.1 |

16 | 11.3 | 11.3 | 9.2 | 32 | 18.4 | 18.4 | 18.6 | STD | 26.5 | 24.1 | 17.8 |

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**MDPI and ACS Style**

Choi, W.; Chang, Y.-S.; Jung, Y.; Song, J. Low-Power LoRa Signal-Based Outdoor Positioning Using Fingerprint Algorithm. *ISPRS Int. J. Geo-Inf.* **2018**, *7*, 440.
https://doi.org/10.3390/ijgi7110440

**AMA Style**

Choi W, Chang Y-S, Jung Y, Song J. Low-Power LoRa Signal-Based Outdoor Positioning Using Fingerprint Algorithm. *ISPRS International Journal of Geo-Information*. 2018; 7(11):440.
https://doi.org/10.3390/ijgi7110440

**Chicago/Turabian Style**

Choi, Wongeun, Yoon-Seop Chang, Yeonuk Jung, and Junkeun Song. 2018. "Low-Power LoRa Signal-Based Outdoor Positioning Using Fingerprint Algorithm" *ISPRS International Journal of Geo-Information* 7, no. 11: 440.
https://doi.org/10.3390/ijgi7110440