The MC-CDMA System Using LS Codes and Nonorthogonal Subcarriers

In this paper, the integration of large-area-synchronized code division multiple access (LAS-CDMA) technology and multicarrier technology is studied. Single cell LAS-CDMA system takes LS codes as its spread spectrum code which have good correlation property, so that the inter-symbol interference (ISI) and multiple access interference (MAI) can be eliminated by finely designing the LS codes. The system model is given in this paper. The received signal especially the interference is well analyzed. Simulational performance and their comparison are given. By integrating multicarrier technology into LAS-CDMA system, much better capacity or performance than that of ordinary multicarrier code division multiple access (MC-CDMA) system can be achieved. In addition, nonorthogonal subcarriers are possible to be applied to LAS-CDMA system as long as most of the interference is removed. As a result, the frequency space between two neighbor subcarriers decreases and the spectrum efficiency of such kind of LAS-CDMA system increases greatly