Obtaining Diversity Gain for DTV by Using MIMO Structure in SFN

Abstract

In Digital TV Broadcasting, the Scheme of Single Frequency Network (SFN) has nontrivial advantages. By forming a SFN, a broadcasting system is able to serve an arbitrary large area with the same program within the same frequency block. At the mean time, the SFN structure provides the receiver with a potential of yielding the space diversity gain, while the power in every single transmitter is not increased. However, there are heavy artificial multipath propagation in the area covered by the SFN broadcasting. Traditionally, a transversal equalizer is used at the receiver to remove the SFN interference. The equalizer always cannot converge properly due to the over-long time delay and the over-large magnitude of the different paths from each transmitter of the SFN. To solve the problem, a new model based on the MIMO structure of the SFN is proposed in this paper, where the signal's space information is exploited. With the model in mind, a new receiving scheme is derived. By using a beamformer, signals with different incident angles are separated, so the problem caused by the over-long delay and the over-large magnitude is avoided. A bank of parallel sub-filters are used to remove the residual multipath spread. The space diversity gain is obtained at the output of a combiner.