Zero Noise Figure...............
No, not exactly. What it means is essentially no intermodulation product produced.
In cell and PCS worlds the key to keeping interference from degrading individual channels from causing problems on others via intermodulation products, the capacity for the entire ‘circuit’ to produce intermods is measured. Thus the -153 dBc....decibels below carrier...start with at least two 10 watt in-band tones and measure all INBAND (3rd order) intermod products that fall within the desired band. Too high products and you get interference. A very important measure of performance especially with equipment and tiers on a cell tower.