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Chapter 7. OFDM Communications over Time... > 7.4 Concluding Remarks - Pg. 327

7.4 Concluding Remarks 327 all the MM T M R MIMO channel paths have the same statistics and hence share the same set of linear combining coefficients. Similarly to Zhao et al. (2008), the iterative channel estimator of Zhao, Shi, & Reed (2007) uses a time-domain preamble, frequency-domain pilots, and soft-decoded data. To deal with the MIMO sce- nario, space-time processing and IAI cancelation are included. Since the estimation process is carried out on a per-subcarrier basis, the estimation quality can be improved by a low-pass filter that exploits the frequency-domain channel correlation (Zhao et al., 2007). 7.4 CONCLUDING REMARKS We now summarize some important issues about multicarrier systems transmitting over LTV channels. First, we stress that when the scattering function is separable, the ICI power only depends on the shape of the Doppler power profile and on the normalized maximum Doppler shift max . On the other hand, the ICI power depends neither on the delay power profile of the channel (provided that the CP is sufficiently long) nor on the absolute maximum Doppler shift max . Second, we have shown that many options are available for channel estimation and ICI mitigation, with different performance levels and complexity requirements. In most cases, the use of statistical CSI