tal (ADC) maximum input of 532 mV is at or near the ADC clipping level. Because the minimum Rx sensitivity is associated with a quadrature phase-shift keying (QPSK) modulated signal that requires less Signal to Noise Ratio (SNR) performance as compared to the higher-order modulated signal for the "near" scenario with maximum Rx input levels, we can get away with not using the full dynamic range of the ADC by not achieving the maximum ADC input level. Carrier #1 Carrier #2 10MHz 10MHz IBW (CBRS: 145MHz) OBW = 10MHz + 10MHz = 20MHz FIGURE 3-15 Instantaneous bandwidth (IBW) and occupied bandwidth (OBW) examples. Chapter 3 Hardware system dimensioning Rx/Tx Antenna Switch Connector Primary VCTCXO PLL+VCO Bypass option Secondary Attenutator 0db 31dB FIGURE 3-16 Generic RF receiver block diagram with zero-Intermediate Frequency (IF) interface. Table 3-6 Example receiver sensitivity analysis. Minimum Rx sensitivity ("far") Maximum Rx input level ("near") Antenna Rx Sensitivity -90dBm (min) -25dBm (max) BPF Filter Insertion Loss - 1.5 dB Primary LNA gain 20 dB 20 dB Secondary LNA gain 20 dB 0 dB (bypassed) De-modulator gain/attenuation - -25dB De-modulator output (dBm/Vpp) = -43.5 dBm/6.7 mV = -31.5 dBm/27 mV Baseband gain 20x (13 dB) 20x (13 dB) ADC input (Vpp) 134 mV 532 mV We estimate the receiver SNR for the by looking at the overall received signal level, noise level and noise that is introduced by the receiver as characterized by the Noise Figure (NF). The NF is an indication of the performance reduction in the receiver chain caused by non- ideal components that introduce noise and is measured in dB. Together with gain, it is the key performance number in LNAs. Lower numbers imply better performance, typical values for LNAs being around 1-2 dB. The first LNA in the chain dominates as we know from Friis' equation for noise. As we showed in Chapter 1, O-RAN Overview, we count received SNR as: SNR = S (Signal) - NF 174dBm (Thermal Noise) + 10*LOG(used bandwidth) Assuming -90dB received signal (minimum sensitivity), 2 