Prerequisites

Before You Begin

This chapter builds on propagation fundamentals, antenna array theory, OFDM waveform design, MIMO spatial multiplexing, and RF hardware impairment modelling to develop the theory and practice of millimeter-wave and sub-THz wireless communications.

  • Large-scale propagation and path-loss models(Review ch05)

    Self-check: Can you apply the log-distance path-loss model PL(d)=PL(d0)+10nlog⁑10(d/d0)+XΟƒPL(d) = PL(d_0) + 10n\log_{10}(d/d_0) + X_\sigma and interpret the path-loss exponent nn for different environments?

  • Small-scale fading and multipath channel models(Review ch06)

    Self-check: Can you describe Rayleigh and Rician fading, define coherence bandwidth BcB_c and coherence time TcT_c, and explain the tapped-delay-line channel model?

  • Antenna arrays and beamforming fundamentals(Review ch07)

    Self-check: Can you compute the array factor for a uniform linear array (ULA), derive the half-power beamwidth ΞΈ3dBβ‰ˆ0.886Ξ»/(Nd)\theta_{3\text{dB}} \approx 0.886\lambda/(Nd), and explain how phased arrays steer their beams?

  • OFDM waveform structure and resource grid(Review ch14)

    Self-check: Can you describe the OFDM signal model, define the cyclic prefix length relative to the channel delay spread, and explain subcarrier spacing and numerology in 5G NR?

  • MIMO spatial multiplexing and precoding(Review ch15)

    Self-check: Can you write the MIMO signal model y=Hx+n\mathbf{y} = \mathbf{H}\mathbf{x} + \mathbf{n}, explain SVD-based precoding, and compute the achievable rate with water-filling power allocation?

  • Multi-user MIMO and beamforming(Review ch16)

    Self-check: Can you explain zero-forcing and MMSE precoding for the multi-user MIMO downlink and describe how spatial degrees of freedom are shared among users?

  • RF hardware impairments: phase noise, PA nonlinearity, ADC quantisation(Review ch23)

    Self-check: Can you model phase noise as a Wiener process, describe the impact of PA nonlinearity on OFDM signals (PAPR, EVM), and quantify the effect of low-resolution ADCs on receiver performance?

Notation for This Chapter

Symbols introduced in this chapter. See also the NGlobal Notation Table master table.

SymbolMeaningIntroduced
PLCI(f,d)PL^{CI}(f,d)Close-in free-space reference distance path loss (dB)s01
nnPath-loss exponent (PLE) in the CI models01
XΟƒX_\sigmaShadow fading, XΟƒβˆΌN(0,Οƒ2)X_\sigma \sim \mathcal{N}(0,\sigma^2) (dB)s01
FRF\mathbf{F}_{\mathrm{RF}}Analog (RF) precoding matrix with unit-modulus entriess02
FBB\mathbf{F}_{\mathrm{BB}}Digital (baseband) precoding matrixs02
Nt,NrN_t, N_rNumber of transmit and receive antennass02
NRFN_{\mathrm{RF}}Number of RF chainss02
NsN_sNumber of data streamss02
dFd_FFraunhofer (far-field) distance: dF=2D2/Ξ»d_F = 2D^2/\lambdas05
Ξ±atm(f)\alpha_{\mathrm{atm}}(f)Atmospheric absorption coefficient (dB/km) at frequency ffs05
TcT_cChannel coherence times03
NBN_BNumber of beams in the codebooks03