Bit Error Rate vs Signal-to-Noise Ratio for various modulation schemes
Eb/N0: Energy per bit to noise power spectral density ratio. The fundamental SNR measure.
BER: Bit Error Rate - fraction of bits received incorrectly. Target: 10⁻⁶ or better.
Waterfall Region: Where BER drops rapidly with increasing SNR. Want to operate here.
Error Floor: Some systems show BER leveling off at high SNR (due to implementation issues).
Coding Gain: How much less SNR needed with error correction for same BER.
Trade-off: Higher-order modulation = more bits/symbol but needs more SNR for same BER.