Increasing the symbol rate in QAM system using a new set of orthonormal basics functions

This paper proposes a new technique to increase the symbol rate in Quadrature Amplitude Modulation (QAM) using a new set of orthonormal functions. The proposed technique increases the rate of QAM symbols without increasing the bandwidth of the modulated signal or increasing the modulation order of the QAM symbol. The set of orthonormal functions consists of four shaped-sinusoidal functions. The shaping functions are Hilbert-Transform pair. The proposed QAM modulator modulates two independent complex symbols in the same time. Each modulated symbol uses two different functions from the proposed set. The paper shows the structure of the modulator and demodulator of the proposed system. The paper presents different shaping pulses, which can be used with the proposed system. Keywords: Quadrature amplitude modulation, Orthogonal shaping shapes, Hilbert transform, Complex exponential carriers, Inter-symbol interference