A hardware detector for constant envelope quadrature-quadrature phase-shift keying (CEQPSK) is proposed. It uses appropriate hard decisions; yet, it achieves optimum probability of bit error performance, unlike the suboptimum detector of Saha and Birdsall. This optimum performance is verified through Monte Carlo computer simulations. Additionally, a more correct expression is given for the prob...

This paper presents new visualization techniques for 4D Quadrature-Quadrature Phase Shift Keying (QPSK), Saha’s Constant Envelope (CE) QPSK, and Cartwright’s CEQPSK in ideal bandlimited channels. The signal diagrams analyzed are: time-signal eye patterns for 4D passband signals, 2D complex trajectory diagrams of baseband signals, and time-signal eye patterns for the 1D outputs of the baseband m...

Traditionally, carrier synchronization (sync) techniques have been developed assuming that the modulation format and signal constellation characteristics are known a priori. By modulation format we mean that the modulation index is chosen so that either the carrier is fully suppressed or a residual carrier component remains. By constellation characteristics we refer to the shape of the constell...

The bit error rate (BER) performance of an M branch maximal-ratio combiner (MRC) for the detection of signals in a correlated Nakagami-fading channel is analyzed. Coherent and incoherent detection of frequency shift-keying (FSK) and phase-shift keying (PSK) signals are considered. It is assumed that the fading parameters in each diversity branch are identical. The effect of correlation is studi...

OFDM (Orthogonal Frequency Division Multiplexing) transmissions are arising as important modulation techniques because of its robustness against interference. Various modulation schemes have been used to implement OFDM. In this paper, the OFDM transceiver system is implemented using MATLAB. Gaussian Minimum Shift Keying modulation technique has been implemented in the proposed OFDM. The bit err...

Spectral, and energy-efficient, communication is essential for the current future wireless generations. Therefore a novel OFDM with double quadrature signed index shift keying (OFDM-DQSISK) proposed. Double levels of (ISK) system proposed to enhance spectral efficiency modulation (OFDM-IM) system. In DQSISK level one, variable α its jα are exploited differentiate between indices active in-phase...

Differential-quadrature phase-shift-keying (DQPSK) can, unlike on-off-keying (OOK), be impaired by nonlinear phase noise (NPN). It has been shown that optical phase conjugation (OPC) is an effective compensation scheme for NPN resulting from the ASE of EDFAs (ASE-NPN). In this paper we discuss the influence of NPN resulting from modulator imperfections (MI-NPN). We show that MI-NPN can be compe...

A cognitive radio (CR) is a transceiver which automatically detects the available unused channels in the wireless spectrum. A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) to coexist with the primary users (PUs) or enabling the SUs to use the unoccupied portion of the spectrum. In this paper, the ergodic capacity maximization problem is studied in Rayleigh...

We present a technique to derive -quadrature amplitude modulation (QAM) signals from quaternary phase-shift keying (QPSK) constellations when = 2 and is an even number. By utilizing QPSK Golay sequences, we have constructed -QAM sequences with low peak-to-mean envelope power ratios. Several upper bounds for these -QAM sequences were derived.

This paper presents the advantage of using a new modulation scheme called dual carrier Modulation (DCM) compared to classical Quadrature Phase Shift Keying (QPSK) modulation. This comparison is done at data transmission broadband in Multiband OFDM system (MBOFDM) based on Ultra Wide Band UWB. Simulation results show that the use of the modulation DCM for high data rates is more efficient compar...