# Received Signal Strength Indication (RSSI) of 2.4 GHz and 5 GHz Wireless Local Area Network Systems Projected over Land and Sea for Near-Shore Maritime Robot Operations

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Path Loss Models

#### 2.2. Experiment Description

## 3. Results

- The full two-ray path loss model from Equation (5)
- The approximate region-two, two-ray path loss model (${h}_{t}\le d\le {d}_{c}$). This is identical to the free space path loss model
- the approximate region-three, two-ray path loss model ($d>{d}_{c}$). The respective frequencies and transmitting antenna heights are labeled in their respective subplots.

## 4. Discussion

## Supplementary Materials

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Appendix A

**Figure A1.**Mean (green for land data, blue for sea data), standard deviation (translucent magenta), and 95% confidence interval (translucent cyan) of raw RSSI versus distance data with a bin size of 2.5 m.

Experiment | $\overline{\mathit{\sigma}}\left[\mathbf{d}\mathbf{B}\mathbf{m}\right]$ | $\overline{95\mathit{\%}\mathit{C}\mathit{I}}\text{}$ | |
---|---|---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | 2.00 | 1.68 |

Sea | 1.34 | 0.93 | |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | 2.07 | 1.82 |

Sea | 0.99 | 0.87 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | 1.44 | 1.64 |

Sea | 1.04 | 0.80 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | 1.57 | 1.42 |

Sea | 1.46 | 1.08 |

## References

- Balkees, S.; Sasidhar, K.; Rao, S. A survey based analysis of propagation models over the sea. In Proceedings of the 2015 International Conference on Advances in Computing, Communications and Informatics (ICACCI); IEEE: Kochi, India, 2015; pp. 69–75. [Google Scholar]
- Reyes-Guerrero, J.C.; Bruno, M.; Mariscal, L.A.; Medouri, A. Buoy-to-ship experimental measurements over sea at 5.8 GHz near urban environments. In Proceedings of the Mediterranean Microwave Symposium (MMS), 2011 11th; IEEE: Hammamet, Tunisia, 2011; pp. 320–324. [Google Scholar] [Green Version]
- Lee, J.H.; Choi, J.; Lee, W.H.; Choi, J.W.; Kim, S.C. Measurement and Analysis on Land-to-Ship Offshore Wireless Channel in 2.4 GHz. IEEE Wirel. Commun. Lett.
**2017**, 6, 222–225. [Google Scholar] [CrossRef] - Reyes-Guerrero, J.C.; Mariscal, L.A. 5.8 GHz propagation of low-height wireless links in sea port scenario. Electron. Lett.
**2014**, 50, 710–712. [Google Scholar] [CrossRef] - Yee Hui, L.E.E.; Dong, F.; Meng, Y.S. Near sea-surface mobile radiowave propagation at 5 GHz: Measurements and modeling. Radioengineering
**2014**, 23, 825. [Google Scholar] - Choi, D.Y. Measurement of radio propagation path loss over the sea for wireless multimedia. In Proceedings of the International Conference on Research in Networking; Springer: Heidelberg, Germany, 2006; pp. 525–532. [Google Scholar]
- Le Roux, Y.-M.; Ménard, J.; Toquin, C.; Jolivet, J.-P.; Nicolas, F. Experimental measurements of maritime radio transmission channels. In Proceedings of the 9th International Conference on Intelligent Transport Systems Telecommunications (ITST); IEEE: Lille, France, 2009. [Google Scholar]
- Joe, J.; Hazra, S.K.; Toh, S.H.; Tan, W.M.; Shankar, J.; Hoang, V.D.; Fujise, M. Path loss measurements in sea port for WiMAX. In Proceedings of 2007 IEEE Wireless Communications and Networking Conference; IEEE: Kowloon, China, 2007; pp. 1873–1878. [Google Scholar]
- Sim, C.Y.D. The propagation of VHF and UHF radio waves over sea paths. Ph.D. Thesis, University of Leicester, Leicester, UK, November 2002. [Google Scholar]
- Friis, H.T. A note on a simple transmission formula. Proc. IRE
**1946**, 34, 254–256. [Google Scholar] [CrossRef] - Mathuranathan, V. (Ed.) Wireless Communication Systems in MATLAB; 2018; independently published; ISBN 9781720114352. [Google Scholar]
- Rappaport, T.S. Wireless Communications: Principles and Practice; Prentice Hall: Upper Saddle River, NJ, USA, 2001; ISBN 978-0130422323. [Google Scholar]
- Hubert, W.; Le Roux, Y.-M.; Ney, M.; Flamand, A. Impact of ship motions on maritime radio links. Int. J. Antennas Propag.
**2012**, 2012, 1–6. [Google Scholar] [CrossRef] - Zhao, Y.; Ren, J.; Chi, X. Maritime mobile channel transmission model based on ITM. In Proceedings of the 2nd International Symposium on Computer, Communication, Control and Automation; Atlantis Press: Singapore, 2013. [Google Scholar]
- Ang, C.-W.; Wen, S. Signal strength sensitivity and its effects on routing in maritime wireless networks. In Proceedings of the 2008 33rd IEEE Conference on Local Computer Networks (LCN); IEEE: Montreal, QC, Canada, 2008; pp. 192–199. [Google Scholar]
- Google Maps & Google Earth GeoGuidelines. Available online: https://www.google.com/permissions/geoguidelines/ (accessed on 20 June 2019).
- Riplaboratory Kanaloa Wireless Benchmarking. Available online: https://github.com/riplaboratory/wireless_benchmarking (accessed on 20 June 2019).
- Venator, E. Ros Developers ROS nmea_navsat_driver. Available online: http://wiki.ros.org/nmea_navsat_driver (accessed on 20 June 2019).
- ROS. ROS Bags. Available online: http://wiki.ros.org/Bags (accessed on 20 June 2019).
- Spiwak, R.R. Equations for Calculating the Dielectric Constant of Saline Water. IEEE Trans. Microw. Theory Tech.
**1970**, 19, 733–736. [Google Scholar] - Timmins, I.J.; O’Young, S. Marine communications channel modeling using the finite-difference time domain method. IEEE Trans. Veh. Technol.
**2009**, 58, 2626–2637. [Google Scholar] [CrossRef] - Benhmammouch, O.; Caouren, N.; Khenchaf, A. Influence of sea surface roughness on electromagnetic waves propagation in presence of evaporation duct. In Proceedings of the Radar Conference-Surveillance for a Safer World; IEEE: Bordeaux, France, 2009; Volume 1, pp. 1–6. [Google Scholar]

**Figure 1.**Over-land data collection path on Sand Island access road (green), and over-seawater data collection path in the Sand Island channel (blue). Map data © 2018 Google. Reproduced with permission from Google Maps Geoguidelines, 2019 [16].

**Figure 2.**Over-land experimental setup. Ground station transmitting antenna (mounted on tripod, right), and trailered rigid tender serving as mobile station with receiving antenna (left).

**Figure 3.**Over-seawater experimental setup. Ground station transmitting antenna mounted on tripod (

**a**), and rigid tender serving as mobile station with receiving antenna (

**b**).

**Figure 4.**Compiled raw received signal strength indication (RSSI) data over land (green) and seawater (blue) plotted against distance for all eight experiments. RSSI versus distance measurements from all eight experiments (f = frequency, ${h}_{Tx}$ = transmitting antenna height).

**Figure 5.**RSSI data over land (green), RSSI data over and seawater (blue), full two-ray model prediction (cyan), approximate region two, two-ray model prediction (magenta), and approximate region-three, two ray model (red), all plotted against distance. Subplot a plots the $f=2.412\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot b plots the $f=5.240\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot c plots the $f=2.412\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data, and subplot d plots the $f=5.240\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data. Model predictions assume RF system specifications given in Table 2, and perfect ground reflection coefficient ($R=-1$ ).

**Figure 6.**RSSI data plotted with unconstrainted single-variable least squares minimization against the two-ray, region two model, assuming a variable generalized path loss, ${P}_{l}$. Subplot a plots the $f=2.412\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot b plots the $f=5.240\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot c plots the $f=2.412\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data, and subplot d plots the $f=5.240\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data.

**Figure 7.**RSSI data plotted with constrained multi-variable nonlinear least squares minimization against the full two-ray model, assuming a variable generalized path loss, $-25<{P}_{l}<0$ dBm, ground reflectivity, $-1<R<0$, and transmitting antenna height, $1.7<{h}_{Tx}<2.3$ m for the 2 m antenna experiments and $4.7<{h}_{Tx}<5.3$ m for the 5 m antenna experiments. Subplot a plots the $f=2.412\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot b plots the $f=5.240\mathrm{GHz},{h}_{Tx}=2\mathrm{m}$ data, subplot c plots the $f=2.412\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data, and subplot d plots the $f=5.240\mathrm{GHz},{h}_{Tx}=5\mathrm{m}$ data.

Specification | RF System | |
---|---|---|

2.4 GHz WLAN | 5 GHz WLAN | |

IEEE 802.11 channel | 1 | 48 |

Center frequency | 2412 MHz | 5240 MHz |

Channel width | 20 MHz | 20 MHz |

Access point model | Ubiquiti BulletAC-IP67 | Ubiquiti BulletAC-IP67 |

WLAN protocol | Ubiquiti Airmax | Ubiquiti Airmax |

Transmitting power | 18 dBm (63.1 mW) | 16 dBm (39.8 mW) |

Antenna model | Trendnet TEW-AO57 | Trendnet TEW-AO57 |

Antenna type | Omnidirectional | Omnidirectional |

Antenna gain | 5 dBi | 7 dBi |

Antenna vertical beam width | 30° | 15° |

Antenna polarization | Vertical | Vertical |

Transmit EIRP | 23 dBm | 23 dBm |

Experiment | $\mathbf{Crossover}\text{}\mathbf{Distance},\text{}{\mathit{d}}_{\mathit{c}}\left[\mathbf{m}\right]$ |
---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | $404$ |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | 1011 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | 879 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | 2196 |

Experiment | ${\mathit{P}}_{\mathit{l}}\left[\mathbf{d}\mathbf{B}\mathbf{m}\right]$ | r-Squared Fit | |
---|---|---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | −8.7 | 0.82 |

Sea | −11.9 | 0.94 | |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | −10.0 | 0.55 |

Sea | −11.7 | 0.87 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | −3.4 | 0.82 |

Sea | −5.1 | 0.81 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | −8.8 | 0.74 |

Sea | −8.3 | 0.75 |

Experiment | ${\mathit{P}}_{\mathit{l},\mathit{l}\mathit{a}\mathit{n}\mathit{d}}-{\mathit{P}}_{\mathit{l},\mathit{s}\mathit{e}\mathit{a}}\left[\mathbf{d}\mathbf{B}\mathbf{m}\right]$ |
---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | −3.0 |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | −1.7 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | −1.7 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | +0.5 |

Experiment | ${\mathit{P}}_{\mathit{l}}\left[\mathbf{d}\mathbf{B}\mathbf{m}\right]$ | $\mathit{R}[]$ | ${\mathit{h}}_{\mathit{t}}\left[\mathbf{m}\right]$ | r-Squared Fit | |
---|---|---|---|---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | −0.49 | −0.49 | 1.9 | 0.86 |

Sea | −0.33 | −0.33 | 1.8 | 0.96 | |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | −0.48 | −0.48 | 4.9 | 0.76 |

Sea | −0.39 | −0.39 | 5.1 | 0.94 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | Land | −0.45 | −0.45 | 1.9 | 0.89 |

Sea | −0.50 | −0.50 | 2.1 | 0.94 | |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | Land | −0.45 | −0.45 | 4.7 | 0.86 |

Sea | −0.51 | −0.51 | 4.7 | 0.91 |

Experiment | ${\mathit{P}}_{\mathit{l},\mathit{l}\mathit{a}\mathit{n}\mathit{d}}-{\mathit{P}}_{\mathit{l},\mathit{s}\mathit{e}\mathit{a}}\left[\mathbf{d}\mathbf{B}\mathbf{m}\right]$ |
---|---|

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | −2.0 |

$\{\begin{array}{c}f=2.412\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | −1.8 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=2\mathrm{m}\end{array}$ | −2.0 |

$\{\begin{array}{c}f=5.240\mathrm{GHz}\\ {h}_{t}=5\mathrm{m}\end{array}$ | +0.1 |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Yamamoto, B.; Wong, A.; Agcanas, P.J.; Jones, K.; Gaspar, D.; Andrade, R.; Trimble, A.Z.
Received Signal Strength Indication (RSSI) of 2.4 GHz and 5 GHz Wireless Local Area Network Systems Projected over Land and Sea for Near-Shore Maritime Robot Operations. *J. Mar. Sci. Eng.* **2019**, *7*, 290.
https://doi.org/10.3390/jmse7090290

**AMA Style**

Yamamoto B, Wong A, Agcanas PJ, Jones K, Gaspar D, Andrade R, Trimble AZ.
Received Signal Strength Indication (RSSI) of 2.4 GHz and 5 GHz Wireless Local Area Network Systems Projected over Land and Sea for Near-Shore Maritime Robot Operations. *Journal of Marine Science and Engineering*. 2019; 7(9):290.
https://doi.org/10.3390/jmse7090290

**Chicago/Turabian Style**

Yamamoto, Brennan, Allison Wong, Peter Joseph Agcanas, Kai Jones, Dominic Gaspar, Raymond Andrade, and A Zachary Trimble.
2019. "Received Signal Strength Indication (RSSI) of 2.4 GHz and 5 GHz Wireless Local Area Network Systems Projected over Land and Sea for Near-Shore Maritime Robot Operations" *Journal of Marine Science and Engineering* 7, no. 9: 290.
https://doi.org/10.3390/jmse7090290