Virtual MIMO Space Division Multiplexing for MC-CDMA

To increase the data rate without signal bandwidth expansion, a combination of MC system with multiple-input multiple-output (MIMO)-space division multiplexing (SDM) is attractive. MIMO-SDM transmission performance is governed by min {N_t, N_r}, where N_t and N_r are the numbers of transmit and receive antennas, respectively. For downlink transmission, many receive antennas cannot be equipped at a mobile station due to space limitation. Therefore, the achievable data rate is limited by the number of receive antennas. In this paper, we propose a virtual MIMO-SDM for multi-carrier-code division multiple access (MC-CDMA) that can use the signals received via different propagation paths as virtual receive antennas. The equivalent number of receive antennas can be increased by a factor of the number of distinct paths of the channel. We confirm, by computer simulation, the effectiveness of virtual MIMO-SDM in a frequency-selective fading channel.