Title :
Analysis of low-PAR modulation schemes for wideband-CDMA
Author :
Kellermann, Walter ; Granzow, Wolfgang
Author_Institution :
Ericsson Eurolab Deutschland GmbH, Nuremberg, Germany
Abstract :
This paper examines a class of PSK-based, linear modulation schemes for application in direct-sequence CDMA systems with respect to the variation of the (complex) baseband signal envelope. A minimum peak-to-average ratio (PAR) of the envelope reduces the linearity requirements of the power amplifier and increases the power amplifier efficiency, which is of great importance especially for mobile terminals. A generalization of the PAR-efficient π/4-QPSK, denoted as φ-QPSK, was proposed for a wideband-CDMA concept for UMTS/IMT-2000 and is investigated here: fundamental mechanisms determining PAR are identified for both real and complex chip sequences. Theoretical PAR values are derived and lead the way to the design of new concepts for PAR-optimal spread spectrum modulation
Keywords :
binary sequences; broadband networks; code division multiple access; land mobile radio; power amplifiers; quadrature phase shift keying; spread spectrum communication; φ-QPSK; π/4-QPSK; DS-CDMA; PSK; UMTS/IMT-2000; baseband signal envelope; binary input chip stream; complex chip sequences; direct-sequence CDMA systems; linear modulation; low-PAR modulation; minimum peak-to-average ratio; mobile terminals; power amplifier efficiency; power amplifier linearity; real chip sequences; spread spectrum modulation; spreading codes; wideband-CDMA; Baseband; Bit rate; Filters; Linearity; Multiaccess communication; Peak to average power ratio; Phase modulation; Pulse modulation; Pulse shaping methods; Spread spectrum communication;
Conference_Titel :
Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on
Conference_Location :
Sun City
Print_ISBN :
0-7803-4281-X
DOI :
10.1109/ISSSTA.1998.726249
