In this paper, we discuss some applications of adaptive filters in asynchronous DS/CDMA using spreading sequences of different code length. In asynchronous DS/CDMA with same code length, the adaptive filter can suppress the interferences because it operates to orthogonalize to them. In a different code length system, perfect orthogonalization to the interferences is difficult, however, some suppression effect by the adaptive filter is expected. Then we examine the effect by using the adaptive filter on time domain or the adaptive filter on frequency domain. Further, we propose a novel method of interference suppression by using power spectrum and show the effect.
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