Performance evaluation of modified HPSK for wideband CDMA

In mobile communications, power is a very important factor and non-linear amplification of the power amplifier cannot be avoided due to their high power efficiency. An HPSK (hybrid phase shift keying) modulation scheme has been proposed as the spreading technique for W-CDMA and cdma2000. HPSK is a complex spreading scheme that is designed to minimize the zero-crossing signal transition. However, there is a possibility that signal transition of HPSK go through zero. We propose a new modulation scheme for W-CDMA and cdma2000. The scheme is based on HPSK, but we modified the complex scrambling to avoid zero-crossing. We call it as modified HPSK (m-HPSK). It is shown that m-HPSK outperforms HPSK in the presence of non-linear amplification.