SSBSC uses 1/2 of the bandwidth and 1/6 as much RF power as AM modulated 100% .

A low bandwidth signal does not have more power.

digital bandwidth = analogue bandwidth * log2 (1+ SNR)

where SNR = strenthe of signal power/ strength of noise

larger the SNR it is better.

no,because generally the lower frequency side existed for lower bandwidth,and higher frequency side existed higher bandwidth,so thus we can say that lower bandwidth has generally has lower power as compared to higher bandwidth.

"3 dB" is a nickname for "1/2 power".

"1/2 power" in dB = 10 log(1/2) = 10 (-0.30103) = -3.01 dB