A multiple input multiple output orthogonal frequency division multiplexing with index modulation (MIMO-OFDM-IM) communications system, comprising:
- at least two transmit antennas in a transmitter side for transmitting signals obtained after orthogonal frequency division multiplexing with index modulation, wherein each transmit antenna transmits OFDM-IM frames;
- at least two receive antennas in a receiver side for receiving the signals transmitted from the transmit antennas for detection and demodulation;
- a block interleaver in the transmitter side, wherein said block interleaver interleaves the OFDM-IM frames to minimize the correlation between channel coefficients corresponding to different OFDM-IM subcarriers;
- a successive minimum mean square error (MMSE) detector followed by a plurality of log-likelihood ratio (LLR) detectors in the receiver side to detect and demodulate the OFDM-IM frames transmitted from said each transmit antenna, wherein the successive minimum mean square error (MMSE) detector in the receiver side is configured to eliminate interference between OFDM-IM frames transmitted from said each transmit antenna by performing a filtering process, wherein the successive MMSE detector in the receiver side is configured to have an enhanced operation mode based on ordered successive interference cancellation (OSIC) algorithm and calculates a quality measure for each transmit antenna and starts the detection from the one that has a maximum signal-to-noise ratio;
- a wherein a plurality of outputs from the successive MMSE detector are provided as inputs to the plurality of log-likelihood ratio (LLR) detector in the receiver side to perform a search over possible realizations of data symbols for said each subcarriers to calculate a posterior probability ratio, wherein the posterior probability ratio is used as a benchmark for determining whether the corresponding subcarrier of a given transmit antenna is active or not;
- a block deinterleaver in the receiver side which deinterleaves the OFDM-IM frames;
- wherein each branch of the transmitter side uses reference look-up tables or combinatorial number theory for selection of indices of active subcarriers according to index selection data bits;
- wherein a cyclic prefix addition is performed after an inverse fast Fourier transform (IFFT) process on the signals in the transmitter section and a cyclic prefix subtraction is performed after the signals are received at the receive antennas followed by a fast Fourier transform process for the decoupling of the received signals without inter-carrier interference.