Syed Safwan Khalid

A Non-data-aided SNR Estimation Method for Square-QAM System

Envelop-based (EVB) SNR estimators are robust to carrier offset and phase jitter. The performance of such estimators however, degrades with increasing SNR for nonconstant modulus constellations. In this work, we consider the SNR estimation as an optimum scale-invariant rank discrimination testing problem and propose an EVB algorithm that does not fail at high SNR. The performance of this algorithm is evaluated for 16 and 64 square-QAM and compared with popular EVB algorithms, i.e., M_2M_4 and M_6. Under the assumption of no phase/frequency offset errors, the simulation results show comparable performance at low SNR with existing algorithms and a significant improvement at higher SNR.

Analysis of modulation classification techniques using Goodness of Fit testing

Modulation classification is a signal processing technique which can estimate the modulation format of the received signals using multiple hypotheses test In this paper, we have presented an overview of modulation classification techniques based on Goodness-of-Fit tests. We have discussed the classification performance of modulation classification method based on Anderson Darling (AD) test, Cramer Von Mises(CVM) test and Kohnogorov-Smirnov (K-S) test. The results have been evaluated using Quadrature Amplitude Modulation (QAM) for AWGN channel using Monte Carlo simulations.

Robust stochastic integration filtering for nonlinear systems under multivariate t-distributed uncertainties

Abstract Bayesian filtering solutions that are developed under the assumption of heavy-tailed uncertainties are more robust to outliers than the standard Gaussian ones. In this work, we consider robust nonlinear Bayesian filtering in the presence of multivariate t-distributed process and measurement noises. We develop a robust stochastic integration filter (RSIF) based on stochastic spherical-radial integration rule that achieves asymptotically exact evaluations of multivariate t-weighted integrals of nonlinear functions that arise in nonlinear Bayesian filtering framework. The superiority of the proposed scheme is demonstrated by comparing its performance against the cubature Kalman filter (CKF), a robust CKF, and the standard SIF in a representative example concerning bearings-only target tracking.

Modulation classification based on modified Kolmogorov-Smirnov test

A modulation classification method based on modified Kolmogorov-Smirnov (K-S) test is proposed. Unlike modulation classification based on K-S test, the proposed method evaluates the sum of the difference between the empirical distribution obtained from the features extracted from received signals and the hypothesized distribution for each modulation candidate in pool. The results have been evaluated using Quadrature Amplitude Modulation (QAM) for AWGN channel using Monte Carlo simulations. Extensive simulation results demonstrate that the proposed modulation classification method based on modified K-S test offers superior performance as compared to the method based on K-S test.

Area under the ROC Curve of Enhanced Energy Detector

The area under the Receiver-Operating-Characteristic (ROC) curve of a detector is a simple and suitable figure-of-merit of its detection capability. However the problem of determining the Area-Under-the-Curve (AUC) of an ROC is a non-trivial exercise and hence it has gone usually unnoticed in literature. In this report we analyze the AUC of the recently proposed enhanced energy detector for spectrum sensing. We derive a simple expression for the AUC which can also be applied to determine the AUC of the conventional energy detector as a special case.

Angle Differential Modulation Scheme for Odd-Bit QAM

In this paper, a method for differential encoding of odd-bit quadrature amplitude modulation (QAM) is presented. Differential encoding would allow QAM to be transmitted over media where coherent detection is not possible owing to phase ambiguity; it would allow such a transmission without the expense of the overhead incurred in data aided transmission. An example 32-QAM constellation is proposed and the algorithms for differential encoding and decoding of the proposed constellation are presented. The analytical performance of the given scheme is also discussed and is verified using simulation results. Results of differentially encoded detection scheme are also compared with those of coherent detection.