Correlated Scrambling Scheme for Time-Frequency Diversity in OFDM Single-Frequency-Network Systems

For orthogonal frequency division multiplexing based single frequency network systems, such as the terrestrial digital broadcasting systems, the performance of a static/quasistatic receiver at cell edge can be severely degraded by the slow and flat fading effect due to a destructive combination of signals from adjacent transmitters. Recently, the Cyclic Delay Diversity (CDD) and Group-wise Scrambling Diversity (GSD) schemes have been presented to address this issue. However, both the CDD and GSD schemes provide no time diversity against the slow fading nature. Moreover, discontinuities of composite channel responses inherent in the GSD scheme make channel estimation even more difficult.