FREQUENCY DOMAIN EQUALIZATION TECHNIQUES FOR MULTICODE DS-CDMA IN FREQUENCY SELECTIVE RAYLEIGH FADING CHANNEL
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Abstract
Orthogonal multicode 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 multicode 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 circulant matrices. Moreover, a channel interleaving method, called chip interleaving is used to improve the performance of multicode DS-CDMA system.
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References
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