### Instruction:

Extract the cause and effect entities from the following sentence:
At the same time, “it is a challenging environment for aeronautical communications due to the aeronautical channel characteristics and the current usage of the band” (Ref

### Assistant:

NOT_RELEVANT: (Ref.
VARIABLE: the current usage of the band
CONDITION: is a challenging environment for aeronautical communications
KEYWORD: due to
AND: and
EFFECT_1: it is a challenging environment for aeronautical communications
CAUSE_1: the aeronautical channel characteristics
CAUSE_2: the current usage of the band

