AbstractIn a multipath fading channel, the arrival time delay difference of multipath signals gives rise to an asymmetric transfer function of the channel, thereby causing cross‐channel‐interference (CCI) between in‐phase and quadrature channel components of a transmitted signal. This paper proposes the use of CCI for detecting multipath signals and roughly estimating multipath delay spread in a digital mobile communication environment.First, the relation between CCI and multipath signal delay time is analyzed under the assumption of static two‐ to three‐ray multipath signals, taking BPSK and QPSK as examples.Next, taking BPSK as an example, the existence of a close relation between CCI and delay time difference or between CCI and delay spread under quasi‐static and Rayleigh fading multipath signal conditions is shown by theoretical analysis and computer simulation. The correspondence between CCI and bit error rate (BER) performance also is studied by computer simulation, and good agreement is found.Finally, the relations obtained were confirmed by laboratory measurements. Accordingly, multipath signal can be detected from CCI. Moreover, rough estimation of delay spread and variation characteristic of BER can be obtained from CCI. Thus, CCI can be used as an effective piece of information for evaluating transmission quality in digital mobile co