Constant envelope enhanced FQPSK and its performance analysis

• Published in: Journal of communications and networks Vol. 13; no. 5; pp. 442 - 448
• Main Authors: Xie, Zhidong, Zhang, Gengxin, Dongming Bian
• Format: Journal Article
• Language: English
• Published: Séoul Editorial Department of Journal of Communications and Networks 01.10.2011; Korean Institute of Communication Sciences; 한국통신학회
• Subjects: Applied sciences; Bit error rate; Coding, codes; Constant envelope enhanced Feher quadrature phase shift keying (FQPSK); constant envelope modulation (CEM); Detectors; Exact sciences and technology; FQPSK; high power amplifier (HPA); Information, signal and communications theory; Performance analysis; Phase shift keying; Receivers; satellite and space communications; Satellite telecommunications. Space telecommunications; Satellites; Signal and communications theory; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Viterbi algorithm; 전자/정보통신공학; Performance evaluation; High performance; satellite and space communications; Input signal; Bit error rate; Space telecommunication; constant envelope modulation (CEM); high power amplifier (HPA); Quadrature phase shift keying; Viterbi code; High power; Viterbi algorithm; Simulation; Power amplifier; Constant envelope enhanced Feher quadrature phase shift keying (FQPSK); FQPSK; Signal distortion
• ISSN: 1229-2370; 1976-5541
• DOI: 10.1109/JCN.2011.6112300

It's a challenging task to design a high performance modulation for satellite and space communications due to the limited power and bandwidth resource. Constant envelope modulation is an attractive scheme to be used in such cases for their needlessness of input power back-off about 2~3 dB for avoidance of nonlinear distortion induced by high power amplifier. The envelope of Feher quadrature phase shift keying (FQPSK) has a least fluctuation of 0.18 dB (quasi constant envelope) and can be further improved. This paper improves FQPSK by defining a set of new waveform functions, which changes FQPSK to be a strictly constant envelope modulation. The performance of the FQPSK adopting new wave- form is justified by analysis and simulation. The study results show that the novel FQPSK is immune to the impact of HPA and outperforms conventional FQPSK on bit error rate (BER) performance. The BER performance of this novel modulation is better than that of FQPSK by more than 0.5 dB at least and 2 dB at most.