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(j/spl omega/). The Hilbert transform is used to calculate the phase of H(j/spl omega/) from its magnitude. Inverse discrete Fourier transformation (IDFT) of H(j/spl omega/) yields h(t). The Hilbert transform relation is applicable provided H(j/spl omega/) 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.