Increasing the Bandwidth Efficiency of OFDM-N/MFSK

Based on noncoherent transmission schemes using subspaces, we propose a method for OFDM-MFSK, which combines subspaces of different dimensions. The assumed channel is a Rayleigh block fading channel. We show, how to combine subspaces of different dimensions and define a criterion for the mapping. The combination of subspaces of different dimensions offers the possibility to increase the bandwidth efficiency of OFDM-MFSK. An upper bound of 1 bit / s Hz can be approached.