Chip waveform shaping for band-limited MC-DS-CDMA

This paper jointly optimizes the chip waveform and the carrier spacing in order to minimize the multiple access interference (MAI) in band-limited asynchronous multicarrier direct sequence code-division multiple access (MC-DS-CDMA) systems. The methodology uses a polynomial to synthesize the elementary density function, which characterizes the band-limited chip waveform. It is shown that using a simple polynomial representations for the elementary density functions (with only a few terms) the proposed chip waveforms and carrier spacings considerably reduce the MAI compared to the existing chip waveforms, particularly the commonly used raised cosine waveform, when the roll-off factor is large