In this paper, a multiple-access spread-spectrum communication system using binary frequency shift keying (BFSK) or M -ary frequency shift keying (MFSK) and noncoherent demodulation is considered. In contrast to previous work typically assuming that the frequency shift keying (FSK) tones are nonoverlapping after direct-sequence (DS) spreading, here we consider a spread-spectrum multiple-access ...

The frequency shift of the ultra-narrow frequency shift keying (UNFSK) is far less than the ordinary binary frequency shift keying (FSK) method. Because the two frequencies of UNFSK are extremely close, the traditional demodulation method cannot separate them successfully. This study aims to successfully demodulate the UNFSK signals by applying cycle extension and notch filter. The signal proce...

AbstmctThis paper proposes new multiuser detectors for frequency-hopped spread spectrum multiple-access (FHSSMA) based on binary frequency shift keying (BFSK) modulation and channelized frequency hopping. With knowledge of hopping sequences and envelopes of active users, the proposed scheme is a sub-optimal detector under maximum likelihood test. Diversity combining is employed as an anti-multi...

This article presents a novel algorithm based on the cross-Wigner-Ville Distribution (XWVD) for optimum phase estimation within the class of phase shift keying signals. The proposed method is a special case of the general class of cross time-frequency distributions, which can represent the phase information for digitally phase modulated signals, unlike the quadratic time-frequency distributions...

In this paper, we investigate the bit error rate (BER) performance of Orthogonal frequency division multiplexing (OFDM)-Binary phase shift keying (BPSK) OFDM-Quadrature phase shift keying (QPSK), OFDM-Quadrature amplitude shift keying (QAM) over different fading channels. The performance of transmission modes are evaluated by calculating the BER versus signal to noise ratio (SNR) under the Addi...

Channel estimation is usually needed to compensate for the amplitude and phase distortions associated with a received orthogonal frequency-division multiplexing (OFDM) waveform. This paper presents a systematic approach for analyzing the bit-error probability (BEP) of equalized OFDM signals in Rayleigh fading. Closed-form expressions for BEP performance of various signal constellations [phase-s...

In this paper we describe a multiple-access protocol in which different users are assumed to share the same bandwidth and the same pulse. Users employ the same modulation (binary-phase shift keying, quadrature-phase shift keying, and rectangular-phase shift keying are considered) with different transmitted magnitude, and are discriminated on the basis of the corresponding magnitude at receiver ...