In this paper, we propose a novel on-line blind demodulation algorithm for Quadrature Amplitude Modulation (QAM). The proposed approach can demodulate QAM signal without constellation knowledge, and reach the theoretical optimal performance under the constraint of sequential detection. Numerical simulations are provided to validate the analytical results. Results show that when iterations are l...

Optical quadrature amplitude modulation (QAM) is experimentally demonstrated with a low-complexity modulator based on a semiconductor optical amplifier and electroabsorption modulator. Flexible amplitude/phase format transmission is achieved. The applicability of octary QAM for coherent optical access networks with sustainable 3 Gb/s per-user bandwidth is investigated for a long reach of 100 km...

For quadrature amplitude modulation (QAM) systems, the joint blind equalization (JBE) algorithm, concatenation of two di erent equalization modes, has been widely used. After the eye is opened by the blind equalization mode, the decision-directed (DD) mode follows to improve the equalization performance with fast convergence. This paper proposes a shell partition-based CMA (SPCMA) which acts as...

This paper proposes hardware architectures of adaptive equalizers applicable to both the quadrature amplitude modulation (QAM) and vestigial sideband modulation (VSB) systems. This paper presents digitization methods for QAM and VSB systems requiring a low hardware cost with the performance comparable to that of the algorithm employing oating-point operations. To reduce the hardware cost of the...

An automatic method for classifying frequency shift keying (FSK), minimum (MSK), phase (PSK), quadrature amplitude modulation (QAM), and orthogonal division multiplexing (OFDM) is proposed by simultaneously using normality test, spectral analysis, geometrical characteristics of in-phase-quadrature (I-Q) constellation diagram. Since the extracted features are unique each modulation, they can be ...

The paper proposes a novel spread quadrature amplitude modulation (S-QAM) technique with high SNR improvement for high-order QAM channels. Simulated and experimental bit error rate (BER) performance analyses of the proposed technique in blind and non-blind equalizers are obtained by using single carrier (SC) WiMAX (IEEE 802.16-2004) radio. Instead of using any one particular type of channel pro...

A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-polarization (DP)-16-QAM transmission systems. By combining QPSK partitioning, maximum likelihood (ML) detection and phase offset estimation between signals in different polarizations, simulation and experimental results for a 200 Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best...

12. Considering discrete-time channels, sketch a chart showing the following plots: (a) Continuous-valued AWGN channel capacity (bits/symbol) as a function of SNR (b) Maximal conveyed information as a function of SNR for the following alphabets: 2-PSK, 4-PSK, 16-QAM, 64-QAM The characteristic shapes of the curves and asymptotic behaviors are essential. 13. The capacity per symbol for a continuo...