Title :
An improvement of nonlinear characteristics in DS-SSMA communication systems using equalizers
Author :
Kusaka, Hiroji ; Kominami, Masanobu ; Kitai, Daisuke ; Chen, Ling ; Takara, Tadarnasa
Author_Institution :
Dept. of Electr. & Electron. Syst., Osaka Prefectural Univ., Sakai, Japan
Abstract :
This paper proposes an improvement method of the deteriorated characteristics on account of the nonlinearity in direct sequence spread spectrum multiple access (DS-SSMA) communication systems. Where, a traveling wave tube (TWT) is adopted as nonlinear circuit in which the amplitude nonlinearity and AM/PM conversion are assumed to be relatively small. The transmission signal is expressed in two quadrature components and an equalizer of feed-forward transversal type is used to improve the nonlinear characteristics. The calculation results show that the significant improvement can be obtained from a simple equalizer using the least mean square algorithm
Keywords :
adaptive equalisers; feedforward; least mean squares methods; multi-access systems; nonlinear network analysis; pseudonoise codes; spread spectrum communication; travelling wave amplifiers; travelling wave tubes; AM/PM conversion; DS-SSMA communication systems; TWT amplifier; adaptive equalizers; amplitude nonlinearity; direct sequence spread spectrum multiple access; feedforward transversal equalizer; least mean square algorithm; nonlinear characteristics; nonlinear circuit; quadrature components; transmission signal; traveling wave tube amplifier; Band pass filters; Envelope detectors; Equalizers; Feedforward systems; Least mean square algorithms; Linear circuits; Nonlinear distortion; Signal to noise ratio; Spread spectrum communication; Tin;
Conference_Titel :
Spread Spectrum Techniques and Applications Proceedings, 1996., IEEE 4th International Symposium on
Conference_Location :
Mainz
Print_ISBN :
0-7803-3567-8
DOI :
10.1109/ISSSTA.1996.563214
