ON THE PERFORMANCE OF SINGLE-FREQUENCY NETWORKS IN CORRELATED SHADOW FADING

All transmitters in a Single Frequency Network (SFN) simultaneously tr ansmit the same information within the same frequency block. Simulcast ing provides a diversity gain which has been shown to yield good cover age. In traditional analysis uncorrelated shadow fading is used. In so me cases this assumption does not capture the behaviour of the shadow fading, e.g. when several transmitters are shadowed by a large obstacl e. In this paper we investigate the changes in coverage due to correla tion among the received signals field strength from different transmit ters. A spatial shadow fading correlation model is proposed and valida ted using the Blomquist-Ladell [13] prediction method on a digital ter rain data base. Results for both wide area and local SFN show that the coverage properties depends on the correlation in the shadow fading. This will affect the planning process since strong correlation, due to the structure of the terrain, yields better coverage for high transmi tter powers (interference limited systems) and worse coverage for low transmitter powers (noise limited systems).