Frequency domain equalization techniques for multicode DS-CDMA in frequency selective Rayleigh Fading channel

Abstract EN

Orthogonal multimode direct sequence code division multiple access (DS-CDMA) has the flexibility in offering high data rate services.

However, in a frequency-selective fading channel, the bit error rate (BER) performance is severely degraded since the orthogonality among spreading codes is partially lost.

In this paper, frequency-domain equalization (FDE) and space antenna diversity combining are applied to orthogonal multimode DS-CDMA in order to restore the code orthogonality and improve the BER performance of the system.

Two methods of FDE are considered, the first method based on fast Fourier transform (FFT), while the second method based on circulate matrices.

Moreover, a channel interleaving method, called chip interleaving is used to improve the performance of multimode DS-CDMA system.