A Multipath Fading Channel Model for Terrestrial Digital Radio Systems

The frequency transfer function of a multipath fading channel is examined in terms of its effects on digital radio signals. The transfer function is expanded into a power series about the channel center frequency and the coefficients are related to the multipath structure. It is then shown that, in the channelized common carrier bands below 15 GHz, the first two (complex) terms of the power series are usually sufficient for characterizing multipath effects. This demonstration is based on a mean-square error-of-fit measure which is applied to the multipath fading response and evaluated under some worst-case assumptions.