Diversity Analysis of Time-Indexed Media-Based Modulation

Time-indexed media-based modulation (TI-MBM) is a block transmission scheme, where a block of N time-slots forms a frame of which only K time-slots are used for data transmission (active slots) and the remaining N - K time-slots are left vacant (inactive slots). The choice of the active timeslots conveys additional information bits along with the bits conveyed by the MBM signals transmitted in the active timeslots. It has been shown that TI-MBM can achieve improved bit error performance compared to the conventional MBM scheme. However, a mathematical diversity analysis of TI-MBM has not been reported in the literature so far. In this paper, we view the time-slot indexing as coding across time (since the choice of active and inactive time-slots are dependent on each other) and carry out a mathematical analysis of the diversity performance of TIMBM. Our analytical results show that, while conventional MBM can not extract the multipath diversity of the channel, TI-MBM can achieve higher diversity orders by extracting the channel multipath diversity for suitable choice of system parameters. We provide simulation results that support the analytically predicted diversity orders.