Low complexity Frequency Domain Turbo Equalization based on single frequency tone in MIMO systems

A novel Frequency Domain Turbo Equalization (FD-TE) is proposed in multiple input multiple output (MIMO) systems, in which equalization is executed on Single Frequency Tone (SFT). It is proposed that received data from all receive antennas on one frequency tone are considered jointly, and then minimum mean square error (MMSE) equalization is implemented. This algorithm can reduce the calculation complexity greatly, and has the same performance as the conventional algorithms. After equalization, data from one transmit antenna on all frequency tones are processed together and transformed into time domain. Later, extrinsic Log-likelihood ratio (LLR) is calculated and sent to Soft-In Soft-Out (SISO) decoder. Theoretical deduction and simulation prove that it can obtain the same performance with a low complexity.