Chip waveform design for DS/SSMA systems with aperiodic random spreading sequences
IEEE Transactions on Wireless Communications
Interference control and chip waveform design in multirate DS-CDMA communication systems
IEEE Transactions on Wireless Communications
An optimal signal design for band-limited asynchronous DS-CDMA communications
IEEE Transactions on Information Theory
An overview of air interface multiple access for IMT-2000/UMTS
IEEE Communications Magazine
Optimum Second Order Polynomial Nyquist Windows for Reduction of ICI in OFDM Systems
Wireless Personal Communications: An International Journal
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The conventional frequency domain square-root raised cosine (Nyquist) chip waveform has much poorer anti-multiple-access-interference (anti-MAI) capability than the optimal band- limited waveform in direct sequence code division multiple access (DS-CDMA) systems. However, the digital implementation of the optimal chip pulse is very costly due to the slow decaying rate of the time waveform. In addition, its eye diagram and envelope uniformity are worse than the Nyquist pulse for a wide range of roll-off factor, which will incur performance degradation due to timing jitters and post non-linear processing. In this paper, based on an elementary density function of a second-order polynomial, a class of second-order continuity pulses is proposed. From this class of pulses, we can find some members having faster decaying rate, bigger eye opening, more uniform envelope and stronger anti-MAI capability than the Nyquist waveform. The normalized-band-width-pulse-shape-factor product, the decaying rate of the tail of the time waveform, the opening of the eye diagram, and the envelope uniformity of the second-order continuity pulses are addressed in the paper that provide the basic information for the selection of the chip pulse for CDMA systems.