An improved design of chip waveforms for band-limited DS-CDMA systems |
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Authors: | Nguyen H.H. |
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Affiliation: | Dept. of Electr. Eng., Univ. of Saskatchewan, Saskatoon, Sask., Canada; |
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Abstract: | This paper introduces an efficient and improved design of chip waveforms to minimize the multiple-access interference in band-limited direct-sequence code-division multiple-access (DS-CDMA) systems. For ease of implementation, the DS-CDMA system employs a time-limited chip waveform, whereas its band limitation is ensured by the low-pass filters at both the transmitter and receiver ends. The design uses sinusoids to synthesize the time-limited chip waveform so that the portion of its spectrum across the specified bandwidth is as flat as possible. It is shown that by using a simple series expansion (with only a few terms) the synthesized chip waveforms significantly outperform the spreading/despreading waveforms previously proposed, particularly for large values of the chip duration-bandwidth product. |
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