Optimization of Wireless Communication Coverage in Underground Tunnels Based on Zone Division

Table 1

Examples of wireless coverage optimization scheme in underground tunnels.

Research group	Optimization scheme	Characteristics	Limitations
Li and Wang [9]	Antenna beam width and antenna deployment	(1) Use antennas with narrow beam width	Optimal configuration of antenna parameters is not given
		(2) Deploy antennas on proper locations
Zhao et al. [10]	Antenna diversity	Use spatial and polarization diversities of two antennas	(1) Optimization is limited by antenna locations
			(2) Scheme cannot be adjusted dynamically as the user moves
Zhou et al. [11]	Antenna polarization	Use the horizontally polarized antenna to communicate	(1) Scheme cannot be adjusted dynamically as the user moves
			(2) Optimization is restricted to the case where the receiver is in the far-field region of the transmitter
Bashir [12]	Antenna deployment	Consider the interaction of the effects of antenna polarization and location on field propagation	(1) Optimization is limited by antenna locations
			(2) Scheme cannot be adjusted dynamically as the user moves
			(3) Optimization is restricted to the case where the receiver is in the near-field region of the transmitter
Huo et al. [13]	Antenna deployment	Consider the different effects of antenna polarization on field propagation in the near-field and far-field zones	(1) Optimization is limited by antenna locations
			(2) Scheme cannot be adjusted dynamically as the user moves