Performance Analysis of DWDM-CDD- MC-CDMA System with Space Time Coding

In the micro or pico cellular fiber-radio access system, more than 1000 Base stations (BSs) are likely to be located under the coverage of a single Central office (CO). It would be desirable to accommodate a large number of base-stations under the coverage of a single CO and the promise for support will be Dense wavelength division multiplexing (DWDM). In wireless communications, high data rate with low probability of error can be achieved by using channel coding technique with spatial multiplexing. Space- time block code (STBC) is the best choice for transmit diversity in narrow band environments. However, when used in conjunction with an MultiCarrier Code Division Multiple Access (MC-CDMA) system they achieve full spatial diversity and variable multipath diversity. Cyclic Delay diversity (CDD) benefits from spreading and channel coding that makes it very competitive with STBC's, particularly since it is applicable to any number of transmit antennas with no loss in rate In this article, we present a DWDM-CDD-MC-CDMA system transmitter based on space-time block code. It is shown that for a DWDM-MC-CDMA system, DWDM achieves high data rate and ST-block codes provide maximum spatial diversity. This hybrid architecture makes full use of the high capacity achievement of DWDM system with frequency domain spreading of MC-CDMA system and provides excellent spatial and frequency diversity which is otherwise impossible to realize with standalone CDD or block codes. The simulation and performance analysis of DWDM-CDD-MC-CDMA system reveals that the system performance improves in combination with channel coding which can also provide diversity.