Multiple-Mode OFDM with Block-Wise Index Modulation

A modified multiple-mode orthogonal frequency division multiplexing with index modulation (MM-OFDM-IM), termed MM-OFDM with block-wise IM (MM-OFDM-BIM), is proposed for adjustable-reliability transmission and low-complexity IM detection. Different from the conventional phase-shift keying-based MM-OFDM-IM, the proposed scheme adopts the same mode for each subcarrier within an IM block and uses the two-stage detector, making the mode detection at receiver more robust and of block size-independent detection complexity. By changing the size of IM block, the simulation results show that the proposed scheme can improve the bit error rate performance of low signal-to-noise ratio environment over frequency-selective fading channel with the cost of improvement of spectral efficiency.