The Lattice-reduction aided MIMO receiver with virtual channels has been proposed that can increase transmission speed for a user in downlinks. Although the proposed receiver achieves superior performance even when the number of receive antennas is much less than that of spatially multiplexed streams, however, the receiver has more computational complexity than conventional lattice reduction-aided MIMO receivers. Then, this paper proposes novel techniques to reduce computational complexity for lattice-reduction aided MIMO receivers with virtual channels. In fact, the proposed techniques are shown to reduce the computational complexity to about 40 % of the original configuration in 8 × 2 MIMO-OFDM systems. Even if the proposed techniques are applied, the MIMO receiver is also shown to achieve superior performance in 10×2 MIMO-OFDM systems.