The FFT-based multiuser detection for DS-CDMA ultra-wideband communication systems

With increasing interest in ultra-wideband impulse radio (UWB-IR) for wireless communication systems, the challenges of dealing with the multiple access interference (MAI) and the inter-symbol interference (ISI) become significant. A multiuser detection scheme for UWB-IR systems is demonstrated, based on block-spread code-division multiple-access (BS-CDMA). By inserting the cyclic prefix at the beginning of the data block, the proposed data transmission strategy not only maintains the code orthogonality at the receiver, but also the UWB channel model can also be represented as a block-circulant matrix. With this feature, fast Fourier transform (FFT) based equalization schemes are applied to mitigate the ISI to such an extent that the system performance approaches that of an AWGN channel. It is important to note that the computation complexity of the proposed scheme is significantly less than that of the conventional DS-CDMA UWB schemes.