Pre-equalization Schemes for MIMO CC-CDMA Systems Over Frequency-Selective Fading Channels

Complementary coded code-division multiple access (CC-CDMA) system offers many attractive features over traditional CDMA systems due to its potential to provide ideal correlation properties and interference resistance feature in multiuser communication. However, the presence of multiple access interference (MAI) is one of the main drawbacks in reducing system performance under frequency-selective fading channels. In this paper, time domain pre-equalization (TDPE) is considered for downlink CC-CDMA systems to resist MAI over frequency-selective fading channels with perfect knowledge of channel state information. Pre-equalization shifts the complicated signal processing to the base station reducing the receiver complexity and improving the battery lifetime at the mobile station. We perform a comparison study between multiple-input multiple-output CC-CDMA (MIMO CC-CDMA) with pre-equalization and traditional equalization schemes towards overcoming MAI. The comparison study revealed that TDPE at the transmitter enriches diversity gain and reduces MAI in MIMO CC-CDMA systems with less receiver complexity.