Performance improvement of CDMA/QPSK systems with nonlinear channel using decision feedback equalizers

Abstract

This paper proposes an improvement method of the performance characteristics of quadriphase phase-shift-keyed code-divisoin multiple-access ( C D M A I Q P S K ) system with nonlinear channel such as the satellite repeater which consists of traveling-wave tube (TWT). Where, two adaptive decision feedback equalizers are used to improve the system performance degraded by the nonlinear channel. From calculation results, it is shown that the degradations are improved considerably.

Analysis, Synthesis, and Classification of Nonlinear Systems Using Synchronized Swept-Sine Method for Audio Effects

“…In this section, the frequency responses H i ( f ) described in the previous section are used for a nonlinear model based on a multiple-input single-output (MISO) model [3]. The structure of this model is shown in Figure 2.…”

“…Digital emulations of nonlinear audio effects can be obtained when using a suitable nonlinear model. Such nonlinear models are available in the literature, for example, Volterra model [1], neural network model [2], MISO model [3], NARMAX model [4], hybrid genetic algorithm [5], extended Kalman filtering [6], or particle filtering [7].…”

Quadrature Phase Shift Keying Direct Sequence-Spread Spectrum Code Division Multiple Access with Disparate Quadrature Chip and Data Rates

“…Also, Kusaka et. al., in their paper [9] have proposed a method to improve the performance characteristics of a quadrature phase shift key codedivision multiple-access (CDMA/QPSK) system in a nonlinear channel, for example a satellite repeater which contains a traveling-wave tube amplifier.…”