The MC-CDMA multi-carrier spread spectrum scheme is a potential candidate for the air interfaces of future mobile radio systems. This scheme benefits from the robustness of OFDM multi-carrier transmission to multi-path propagation on one hand and on the other hand from the flexibility of CDMA code division multiple access technique. This thesis investigates the system level performance of MC-CDMA scheme in the downlink. The goal is to validate at the system level the concepts and algorithms of MC-CDMA physical layer. The thesis addresses two connected themes. The first theme concerns the abstraction of the physical layer at the system level. This theme is also referred to as the link to system level interfacing. The main objective of the physical layer abstraction is to define an adequate measure that allows to predict the transmission quality at the system level. In this thesis, we consider the physical layer abstraction with respect to two time scales. The first time scale is macroscopic and averages the transmission of several data frames experiencing independent channel fading realizations. The second time scale is microscopic and includes only one data frame experiencing a particular channel fading realization. The macroscopic abstraction is appropriate for evaluating the system level performance through static system level simulations, whereas the microscopic abstraction is more appropriate for more accurate evaluation of the system level performance and for proper investigation of link adaptation algorithms through dynamic system level simulations. In our study, we analyze the problems raised by the two types of abstraction and propose novel and appropriate solutions. The second theme concerns the evaluation of the cellular capacity performances of the MC-CDMA physical layer for different algorithms and configurations. Using the macroscopic abstraction, we develop a semi-analytical methodology for evaluating the cellular capacity. The capacity is evaluated at both the link level through a novel capacity indicator and at the system level through Monte Carlo static system simulations. The methodology developed here is a pragmatic and efficient tool to identify the physical layer configurations that are best suited for a given environment. Keywords - MC-CDMA, interference modelling, link to system interface, cellular capacity, system level simulations.
On the System Level Performance of MC-CDMA Systems in the Downlink