F-QPSK-A superior modulation for future generations of high-capacity microcellular PCS systems

A coherent F-QPSK modem radio technique is proposed for future generations of high-capacity personal communication services (PCSs) systems. F-QPSK is a constant envelope modulation that is 6 to 8 dB more power efficient than non-constant envelope signalings like the /spl pi//4 DQPSK as used in the US IS-54 digital cellular mobile radio and the Japanese Handyphone standards. A comprehensive evaluation of F-QPSK's adjacent channel interference (ACI) characteristics, spectral efficiency in b/s/Hz/m/sup 2/ and bit error rate (BER) performance in a PCS cellular environment is presented. The results are compared with Gaussian minimum shift keying (GMSK), which is the modulation format adopted in the current PCSs standards DECT and DCS1800. It is demonstrated that F-QPSK has an attainable spectral efficiency of 1.42 b/s/Hz, which is 51% higher than GMSK as used in DECT. The BER performance of F-QPSK is also more robust in both Rayleigh fading and CCI controlled environments.