A Two-Dimensional Linear Pre-Transformed (2DLPT) MIMO-OFDM System

We propose an open-loop two-dimensional linear pre-transformed (2DLPT) multiple-input multiple- output (MIMO) orthogonal frequency division multiplexing (OFDM) system. The n _T N times n _T N 2DPLT, with n _T the number of transmit antennas and N the FFT size in the OFDM modulation, is applied in both spatial and frequency domains and is unitary in individual as well as both domains. While the spatial domain transform converts the transmit diversity from the other transmit antennas to frequency diversity, the frequency domain transform fully exploits the frequency domain diversity made available. More over, the unitary transform guarantees the same ergodic capacity as the non-transformed spatial division multiplexing MIMO-OFDM channel. Therefore, the proposed 2DLPT MIMO-OFDM system achieves full diversity of n _T n _R n _L with n _R and n _L representing the number of receive antennas and the number of multipaths in each transmit-receive antenna pair channel, and full capacity.