In-building wireless radio channel characterization based on energy measurements and the Hilbert transform

A simple, cost-effective means is developed to estimate the impulse response h(t) for wireless radio channels using only the magnitude of the channel transfer function, H(jω). The Hilbert transform is used to calculate the phase of H(jω) from its magnitude. Inverse discrete Fourier transformation (IDFT) of H(jω) yields h(t). The Hilbert transform relation is applicable provided H(jω) is a minimum phase transfer function, and provides a useful lower bound on the time-spread of a non-minimum phase impulse response. An experimental in-building wireless testbed was used to confirm analytical results, for line-of-sight (LOS) and non-LOS (NLOS) transmission in the 1000-2500 MHz range. The minimum phase assumption yields impulse response values which are close to those measured, and simplifies considerably the measurement process