Prerequisites & Notation

Before This Chapter

Chapter 16 is the practical counterweight to the theory of the preceding chapters. You should be comfortable with the RIS hardware primitives of Chapter 2 (PIN/varactor phase shifters, amplitude-phase coupling), the cascaded channel model of Chapter 3 ( $\mathbf{H}_2 \boldsymbol{\Phi} \mathbf{H}_1$ ), and the joint beamforming framework of Chapter 5.

Notation for This Chapter

Measurement-specific notation on top of the single-RIS conventions. Calibration errors are random variables; performance is a distribution over realizations of those errors.

Symbol	Meaning	Introduced
$\tilde{\boldsymbol{\Phi}}$	Measured (imperfect) phase-shift matrix
$\delta_n$	Phase error at element $n$ : $\tilde\theta_n = \theta_n + \delta_n$
$\sigma_\phi^2$	Variance of per-element phase error
$\Gamma$	Reflection coefficient (complex, per element)
$\eta_{\text{cal}}$	Calibration efficiency: fraction of ideal SNR retained
$\mathbf{S}$	S-parameter matrix (VNA output)

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