Multicarrier DS-CDMA systems with multiple chip waveforms

The influence of bandlimited multiple chip waveforms on the performance of asynchronous, multicarrier, direct sequence code-division multiple access (MC-DS-CDMA) systems is investigated for the downlink. The performance criterion is the average multiple access interference (MAI) at the output of a matched filter receiver. An additive white Gaussian noise channel is assumed. It is demonstrated that for carrier spacing c = 1/(1 + β), using the same chip waveform for all the carriers, minimizes the MAI, i.e, there is no need to assign different chip waveforms to different carriers.