()dBm is the recommended radius of a cell for a voice-ready wireless network.  
A、 4
B、 6
C、 7
D、 10
A、 4
B、 6
C、 7
D、 10
A、A. -40dBm signal and -90dBm noise B、B. -50dBm signal and -90dBm noise C、C. -30dBm signal and -90dBm noise D、D. -20dBm signal and -90dBm noise
A、A. Signal strength 0dBm, noise level 6dBm B、B. Signal strength 8dBm, noise level 9dBm C、C. Signal strength 4 dBm, noise level 4 dBm D、D. Signal strength 6dBm, noise level 5 dBm