Study of Cyclic Delay Diversity for Single Frequency Network using DRM Standard

This paper presents a study of cyclic delay diversity (CDD) for a single frequency network (SFN) using digital radio mondiale (DRM) standard. Flat fading over the bandwidth can entirely disrupt the signal during several orthogonal frequency division multiplexing (OFDM) symbols. In such conditions, channel encoding can only partially recover the sent information. In order to overcome this problem, CDD artificially increases the frequency selectivity of the channel by adding a phase to the signal at the emitter side. We describe the principle in the case of two transmit antennas, and for a more complete network model, where three values of phase shifting are considered. We measure the gain provided by CDD for one process on one hand and in average on the other hand. In order to complete the study, we show the effect of the increase of frequency selectivity on the channel estimation performance.