|Protection ratio is the minimum acceptable single entry C/I
for a wanted carrier.
This is defined by ITU-R Recommendations. Recommendation ITU-R S.741 summarises the
protection ratios for different wanted carrier types. Protection ratios are generally
defined in terms of an "allowable" interference level as a proportion of the
thermal noise in a link.
Examples for different wanted carrier types:
- 6% of thermal noise
- PR = C/N + 12.2 dB
- 4% of thermal noise
- PR = C/N + 14 dB
FDM/FM (multiplexed telephony) carrier
- 800 pW0p in 7500 pW0p noise budget, i.e. 10.67% of thermal noise
- PR = C/N + 9.7 dB