7
sizes, and Orthogonal Frequency Division Multiplexing
(OFDM) [4] can enhance communication robustness.
Smaller packet sizes improve transmission success rates by
reducing the amount of data vulnerable to errors, which
lowers the need for repeated transmissions and increases
overall system efficiency. OFDM, widely adopted in
modern wireless communication systems like Wi-Fi and
4G/5G, provides a robust solution by splitting the signal
across multiple subcarriers, each transmitted on different
frequencies. This technique effectively combats interference
and multipath fading—common issues in underground
tunnels where signals may reflect off walls and equipment.
By spreading the data across multiple frequencies, OFDM
ensures that errors affecting one subcarrier do not disrupt
the entire transmission.
Additionally, diversity communication technologies,
which use multiple antennas or transmission paths, further
enhance signal reliability by selecting the strongest signal or
combining multiple signals to minimize the effects of fad-
ing and interference. By employing a combination of these
strategies, the robustness of wireless communication sys-
tems in underground mines can be significantly improved,
maintaining high-quality and reliable communication
despite challenging conditions.
CONCLUSION
Our experiments demonstrate that wireless communica-
tion in underground mining tunnels can be significantly
affected by interference from adjacent wireless communica-
tion channels within the same frequency band. Specifically,
smaller frequency spacing between channels leads to
increased interference, and higher adjacent communication
power intensifies this effect. Additionally, human activity
within the tunnel disrupts the line of sight, causing insta-
bility in signal communication we anticipate that vehicular
movement will have a similar or even greater impact.
We also found that smaller packet sizes result in a lower
packet error rate, enhancing the likelihood that packets suc-
cessfully reach their targets. In noisy environments, larger
packet sizes are more vulnerable to errors, where even one
or two bit errors can cause a packet to fail. The number of
consecutive lost or errored packets indicates the duration
of communication interruptions. Depending on the critical
functions reliant on this communication, extended inter-
ruption times could result in serious consequences—such
as uncontrollable machine actions or unexpected shut-
downs—as observed in the aforementioned mine.
LIMITATIONS
The two CC112x evaluation boards do not fully replicate
the communication system between the machinery and the
remote controller because we lack access to the confidential
specifics of the system. Additionally, the interference signals
generated by our signal generator do not accurately reflect
those found in the actual wireless system in the underground
mine, due to both hardware limitation and confidentiality
issues. Furthermore, the test location in the Safety Research
Coal Mine contains metal mesh in the ceiling and other
nearby metal objects that could affect electromagnetic sig-
nal propagation. Additionally, the simulated human activi-
ties in our tests do not represent the movements of miners
at all in an underground mine. As a result, our test result
only serves as an example of how wireless communication
systems can be impacted by interference from other wireless
sources and human activities.
DISCLAIMER
The findings and conclusions in this paper are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health, Centers for Disease Control and Prevention.
Mention of any company name or product does not consti-
tute endorsement by NIOSH.
REFERENCES
[1] Zhou, C., M. Reyes, and M. Girman, Electromagnetic
Interference (EMI) In Underground Coal Mines: a
Literature Review and Practical Considerations. Mining,
Metallurgy &Exploration, 2022. 39: p. 421–431.
[2] Zhou, C., et al., RF Propagation in Mines and Tunnels:
Extensive measurements for vertically, horizontally, and
cross-polarized signals in mines and tunnels. IEEE
Antennas and Propagation Magazine, 2015. 57(4):
p. 88–102.
[3] Joe Manchin III, G. Mine Safety Information Notice
0808-2010. 2010 Available from: https://minesafety.
wv.gov/wp-content/uploads/2020/12/MSIN-0608-
2010-2.pdf.
[4] Molisch, A.F., Wireless Communications: From
Fundamentals to Beyond 5G, 3rd Edition. 2022: Wiley.
sizes, and Orthogonal Frequency Division Multiplexing
(OFDM) [4] can enhance communication robustness.
Smaller packet sizes improve transmission success rates by
reducing the amount of data vulnerable to errors, which
lowers the need for repeated transmissions and increases
overall system efficiency. OFDM, widely adopted in
modern wireless communication systems like Wi-Fi and
4G/5G, provides a robust solution by splitting the signal
across multiple subcarriers, each transmitted on different
frequencies. This technique effectively combats interference
and multipath fading—common issues in underground
tunnels where signals may reflect off walls and equipment.
By spreading the data across multiple frequencies, OFDM
ensures that errors affecting one subcarrier do not disrupt
the entire transmission.
Additionally, diversity communication technologies,
which use multiple antennas or transmission paths, further
enhance signal reliability by selecting the strongest signal or
combining multiple signals to minimize the effects of fad-
ing and interference. By employing a combination of these
strategies, the robustness of wireless communication sys-
tems in underground mines can be significantly improved,
maintaining high-quality and reliable communication
despite challenging conditions.
CONCLUSION
Our experiments demonstrate that wireless communica-
tion in underground mining tunnels can be significantly
affected by interference from adjacent wireless communica-
tion channels within the same frequency band. Specifically,
smaller frequency spacing between channels leads to
increased interference, and higher adjacent communication
power intensifies this effect. Additionally, human activity
within the tunnel disrupts the line of sight, causing insta-
bility in signal communication we anticipate that vehicular
movement will have a similar or even greater impact.
We also found that smaller packet sizes result in a lower
packet error rate, enhancing the likelihood that packets suc-
cessfully reach their targets. In noisy environments, larger
packet sizes are more vulnerable to errors, where even one
or two bit errors can cause a packet to fail. The number of
consecutive lost or errored packets indicates the duration
of communication interruptions. Depending on the critical
functions reliant on this communication, extended inter-
ruption times could result in serious consequences—such
as uncontrollable machine actions or unexpected shut-
downs—as observed in the aforementioned mine.
LIMITATIONS
The two CC112x evaluation boards do not fully replicate
the communication system between the machinery and the
remote controller because we lack access to the confidential
specifics of the system. Additionally, the interference signals
generated by our signal generator do not accurately reflect
those found in the actual wireless system in the underground
mine, due to both hardware limitation and confidentiality
issues. Furthermore, the test location in the Safety Research
Coal Mine contains metal mesh in the ceiling and other
nearby metal objects that could affect electromagnetic sig-
nal propagation. Additionally, the simulated human activi-
ties in our tests do not represent the movements of miners
at all in an underground mine. As a result, our test result
only serves as an example of how wireless communication
systems can be impacted by interference from other wireless
sources and human activities.
DISCLAIMER
The findings and conclusions in this paper are those of the
authors and do not necessarily represent the official posi-
tion of the National Institute for Occupational Safety
and Health, Centers for Disease Control and Prevention.
Mention of any company name or product does not consti-
tute endorsement by NIOSH.
REFERENCES
[1] Zhou, C., M. Reyes, and M. Girman, Electromagnetic
Interference (EMI) In Underground Coal Mines: a
Literature Review and Practical Considerations. Mining,
Metallurgy &Exploration, 2022. 39: p. 421–431.
[2] Zhou, C., et al., RF Propagation in Mines and Tunnels:
Extensive measurements for vertically, horizontally, and
cross-polarized signals in mines and tunnels. IEEE
Antennas and Propagation Magazine, 2015. 57(4):
p. 88–102.
[3] Joe Manchin III, G. Mine Safety Information Notice
0808-2010. 2010 Available from: https://minesafety.
wv.gov/wp-content/uploads/2020/12/MSIN-0608-
2010-2.pdf.
[4] Molisch, A.F., Wireless Communications: From
Fundamentals to Beyond 5G, 3rd Edition. 2022: Wiley.