FQPSK, power and spectral efficient family of modulations for wireless communication systems

A family of power and spectrally efficient modulations is proposed for wireless mobile, and personal communications services (PCS). This family of modulations is based on the FQPSK processor. The main focus of this paper is to present the latest developments and results of FQPSK modulation with 4 signal states. FQPSK which is a constant envelope modulation has been shown to increase the spectral efficiency and capacity by up to 92% over GMSK which is the current modulation for the DECT European standard in mobile cellular communications. It also outperforms PI/4-DEQPSK which is the current modulation standard used in the USA, under IS-54, and Japan, in power efficiency, battery lifetime, and reduced radiation while maintaining equal capacity. To improve further the spectral efficiency of FQPSK, simple baseband processing and filtering strategies are applied. Such baseband processing leads to a spectral efficiency of 1.6 b/s/Hz, and has BER performance of 1*10-2 for a C/I of 18.5 dB in a hardlimited Rayleigh fading channel. To achieve higher spectral efficiency, FQPSK-4/spl times/4 which is a 16 state modulation is proposed. This modulation can be nonlinearly amplified, and is compatible with 16 QAM. FQPSK has been also shown to be compatible with OQPSK, GMSK, and can be demodulated with their receivers with less than 0.5 dB degradation.<
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