Abstract
OFDM is expected to be a suitable modulation method for digital terrestrial broadcasting systems. One of the reasons is that it makes it possible to construct single frequency networks (SFNs) and effective use of the frequency bands. In a SFN environment, however, some receivers will obtain their signals from more than one transmitter, and the reception quality is degraded by the inter-symbol interference, when the delay spread reaches over guard-interval length of the OFDM systems. This paper studies methods to improve SFN coverage by inserting suitable initial delays in each transmitter and by optimizing the FFT window position of the OFDM demodulator.
