Nyquist pulses for zero inter-symbol interference (ISI)
Bandwidth: Rectangular pulses have infinite bandwidth (sinc spectrum). Pulse shaping limits bandwidth for efficient spectrum use.
Nyquist Criterion: p(nT) = 1 for n=0, 0 for n≠0. Ensures zero ISI at sampling instants!
Roll-off Factor (α): 0 = minimum bandwidth (ideal sinc), 1 = maximum bandwidth (smooth time response).
Raised Cosine: The practical choice. Excess bandwidth = α × symbol rate.
Root Raised Cosine: Split between TX and RX filters for matched filtering.