Linear receivers on MIMO channels: a comparison between DS/CDMA and MC-DS/CDMA

This paper is aimed at presenting a comparison between Direct-Sequence CDMA (DS/CDMA), employing only one carrier, and Multi-Carrier DS/CDMA (MC-DS/CDMA), for information transmission over a Multiple-Input Multiple- Output (MIMO) frequency selective channel with a global bandwidth constraint. Assuming a linear structure at the receiver end, results indicate that MC-DS/CDMA is superior as Channel State Information (CSI) is available. Conversely, for No Channel State Information (NCSI), DS/CDMA exhibits better performance in heavily loaded networks, while MC-CDMA is preferable for low users’ number: since this effect is tied to a more restrictive identifiability condition for the MC-DS/CDMA, its global superiority may be eventually restored by increasing the number of receive antennae. It is also shown that a third modulation format, referred to as hybrid MC-DS/CDMA, seems capable of compromising between the former two.