Synthesized-Isotropic Narrowband Channel Parameter Extraction from Angle-Resolved Wideband Channel Measurements

TL;DR

This work tackles the problem of obtaining antenna-independent large-scale channel parameters from angle-resolved wideband measurements by addressing the bias introduced by non-orthogonal, overlapping scan beams. It introduces a synthesized-isotropic power framework with a unified matrix form and a beam-accumulation correction factor, including an offset-averaged variant to mitigate scalloping without off-grid angle estimation. The method is validated through SV-model simulations and 154 GHz corridor measurements, showing improved accuracy in omni-equivalent power recovery and consistent PL estimates across directional configurations. The practical outcome is a robust, implementable approach for estimating isotropic path loss and related parameters from realistic directional sounding setups at mmWave/THz bands, facilitating antenna-independent channel characterization.

Abstract

Angle-resolved channel sounding using antenna arrays or mechanically steered high-gain antennas is widely employed at millimeter-wave and terahertz bands. To extract antenna-independent large-scale channel parameters such as path loss, delay spread, and angular spread, the radiation-pattern effects embedded in the measured responses must be properly compensated. This paper revisits the technical challenges of path-gain calculation from angle-resolved wideband measurements, with emphasis on angular-domain power integration where the scan beams are inherently non-orthogonal and simple power summation leads to biased omni-equivalent power estimates. We first formulate the synthesized-isotropic narrowband power in a unified matrix form and introduce a beam-accumulation correction factor, including an offset-averaged variant to mitigate scalloping due to off-grid angles. The proposed framework is validated through simulations using channel models and 154~GHz corridor measurements.

Figures (9)

• Figure 1: Omnidirectional measurement vs angle-scanning measurement.
• Figure 2: Radiation patterns of Gaussian beams given by $G \cdot a(\theta, \phi)$ ($\phi_\mathrm{3dB}=\theta_\mathrm{3dB}$).
• Figure 3: Variation of the 1D beam-accumulation factor versus HPBW and ASI for Gaussian beam models. The on-grid accumulation factor is computed by the discrete summation in \ref{['eq:zeta_1d_discrete']} (markers) and by the exact series expression in \ref{['eq:zeta_1d_discrete_bessel']} for uniform full-azimuth scans (solid lines). Furthermore, the within-bin averaged factor is given by \ref{['eq:zeta_delta_avg']} (markers) and by the exact series expression in \ref{['eq:zeta_psi_delta_series']} (dashed lines).
• Figure 4: Radiation patterns of pyramidal horn antenna ($G=26$ dBi, $\theta_\mathrm{3dB}\approx 8^\circ, \phi_\mathrm{3dB}\approx 9^\circ$) Corridor300GHz.
• Figure 5: Illustration of scalloping loss and offset-dependent beam accumulation: normalized received power versus angular index for the on-grid and half-bin-offset AoA cases, and the resulting accumulation factor $\zeta_{\phi_\mathrm{R}}(\delta)$ as a function of the within-bin angular offset $\delta$; the averaged value is $\bar{\zeta}_{\phi_\mathrm{R}}=1.21$.