Time-frequency scrambling scheme for improving cell-edge performance in multi-Cell multimedia broadcast multicast service

In this paper, we propose a novel transmission structure with the time-frequency scrambling scheme. The major concept of this technique is coming from combining the Toshiba's approach and our proposed time-dimension group scrambling scheme. In this technique, several OFDM symbols and several sub- carriers can be grouped into a grid structure and then scrambled by a scrambling pattern, the time- frequency dimension diversity gains are both increased after channel decoder. The time-frequency scrambling scheme uses the random behaviors of transmitted signals from multiple cells to create the plentiful time and frequency channel diversity, indeed, control the coherent time and the interleaver length. Hence, the burst error due to the flat fading and the long-term shadowing fading can be mitigated and channel coding will work more efficiently. The simulation results show that the destructive interference can be improved at the cell-edge by the proposed scheme. The SNR gains can be derived by the proposed scheme for mutli-cell MBMS environments (5 dB and 1.5 dB for two equal-gain and TU6 channels, respectively).