The performance analysis of a multi-carrier CDMA system in mobile environment

Abstract

In this paper, several detection schemes are studied for a multi-carrier code division multiple access (MC-CDMA) system in the downlink case. Both analytical methods and system simulations are used to examine the performance of those detection schemes. The inter-symbol interference (ISI) can be absorbed by guard intervals, so the data in each subcarrier can be well equalized in slowly fading environment in case of coherent detection. Since each individual subcarrier of an MC-CDMA system is flat fading, it is possible to apply differential modulation schemes with non-coherent reception at subcarrier level. In the ideal case, the non-coherent reception provides worse performance than the coherent reception. However, the performance gap between coherent and differential reception reduces with increasing channel estimation and equalization errors. In the extreme cases, in fast-fading environment, the performance of differential detection may even exceed that of a coherent receiver with practical channel estimation methods. This is proved by the simulation results when a simple coherent detection scheme and a differential phase detection scheme are compared. It is also shown in this paper that with a simple equalizer, an MC-CDMA system can provide good performance in multi-user and multipath fading environments. Copyright © 2004 AEI.