Applicable AU/BU only.
Defines the minimum desired level of the average SNR at the AU/BU.
Below this level, if *AtpcOption is enabled, the AU/BU will transmit
ATPC Power-Up messages to the applicable SU/RB.
The *MinimumSNRLevel cannot be higher than *MaximumSNRLevel.
Range: 4 to 60 (dB).