An Efficient Hierarchical Modulation based Orthogonal Frequency Division Multiplexing Transmission Scheme for Digital Video Broadcasting

Due to the increase of users the efficient usage of spectrum plays an important role in digital terrestrial television networks. In digital video broadcasting, local and global content are transmitted by single frequency network and multifrequency network respectively. Multifrequency network support transmission of global content and it consumes large spectrum. Similarly local content are well supported by single frequency network. In order to provide better spectral efficiency both local and global contents are transmitted in single constellation using hierarchical modulation. Hierarchical modulated OFDM system provides good spectral efficiency and robustness to the fading environment. In this paper a hierarchical modulated OFDM system for local service insertion is analyzed and its performance under various channels is been discussed. Convolutional encoder is used in this paper.