Impact of the channel estimation onto the BER-performance of PSAM-OFDM systems in mobile radio channels

Pilot symbol assisted modulation (PSAM) of the subcarriers of an OFDM system seems to be very attractive for high data rate radio systems. It is used, or will be in the near future, in broadcast systems like DVB-T and DRM. Nevertheless, for highly time- and frequency-dispersive radio channels, the channel estimation based on the interpolation between the pilot symbols in time and frequency is very critical. We derive expressions for the gross BER as a function of channel correlation and interpolation filter in time and frequency. Also adjacent channel interference due to Doppler effects is taken into account. Example results are given for the European DVB-T system, which is also a system candidate for the broadband downlink of a new platform concept to enable asymmetric IP-based mobile multimedia services. This concept is under investigation within the German research project UMT-Splus/COMCAR