Intercarrier and intersymbol interference analysis of OFDM systems on time-varying channels

Intersymbol interference (ISI) and intercarrier interference (ICI) for OFDM systems with insufficient guard length was analyzed (Nguyen et al. (2002)) in the case of time-invariant radio channels. This was carried out by truncating the channel impulse response (CIR) in mathematical analysis into two parts, the so-called truncated channels. The same technique is used in this paper to compute the ISI and ICI components for the case of time-varying channels, where again the WSSUS assumption (wide sense stationary uncorrelated scattering) is applied. The exact expression of the ICI power is obtained in dependence of the time correlation function of the channel and the multipath channel profile. Moreover, this ICI power can be well approximated by the sum of the ICI power caused by the insufficient guard interval effect obtained in Nguyen and ICI power caused by the effect of time variations of the channel obtained in Russell et al. (1995). The ISI power is not dependent on the time variations of the channel.