On double chip waveforms for asynchronous DS-CDMA systems

In an asynchronous DS-CDMA system using random signature sequences and correlation receivers, the signal-to-interference ratio (SIR) at the output of each correlation receiver depends on the shape of the chip waveform employed. In this paper, the use of double chip waveforms instead of a single chip waveform is proposed in order to increase the SIR performance. An analytical expression for the SIR when double chip waveforms are used is obtained. Numerical examples are also given to demonstrate the advantage of using double chip waveforms over single chip waveform.