Topic
Keying
About: Keying is a research topic. Over the lifetime, 6598 publications have been published within this topic receiving 82943 citations.
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TL;DR: Close-form expressions for the bit error probability of two non-coherent transmission schemes over L diversity branches being subject to generalized κ-fading are derived and an interesting interplay between the two fading parameters κ and m is revealed.
Abstract: The generalized κ-fading model, characterized by two parameters, κ and m, is a very versatile model and was recently shown to accurately capture the effects of composite shadowing and multipath fading in wireless communication systems. Furthermore, it can be used to model cascade multipath fading, which is relevant in, e.g., mobile-to-mobile communication scenarios. In this paper, we derive closed-form expressions for the bit error probability of two non-coherent transmission schemes over L diversity branches being subject to generalized κ-fading. Specifically, focus is on binary differential phase-shift keying (DPSK) and binary non-coherent frequency-shift keying (FSK) modulation with (post-detection) equal-gain combining at the receiver. We also discuss the extension of our results to M-ary modulation schemes. Considering both independent and correlated fading across the L branches, we derive expressions for the asymptotic diversity order, which reveal an interesting interplay between the two fading parameters κ and m. Moreover, we show that the diversity order of the considered non-coherent transmission schemes is the same as in the case of a coherent transmission scheme. Finally, numerical performance results are presented, and our analytical results are corroborated by means of Monte-Carlo simulations.
38 citations
19 May 1991
TL;DR: An efficient technique for co-channel interference suppression in multi-user indoor radio communication systems is presented and makes use of an antenna array in conjunction with an adaptive combiner that employs a training sequence to adjust the receiver to the desired co-user.
Abstract: An efficient technique for co-channel interference suppression in multi-user indoor radio communication systems is presented. The proposed approach makes use of an antenna array in conjunction with an adaptive combiner that employs a training sequence to adjust the receiver to the desired co-user. A different training sequence known to the receiver is transmitted periodically with the information sequence of each co-user. Signals received at the diversity antennas are weighted and summed to produce a combined signal. The weight coefficients are adjusted such that the reception of the desired signal is enhanced and all interfering signals are attenuated. A complex least-mean-square algorithm based on the method of steepest descent is used for weight adjustment. Computer simulations are presented for a two-antenna system with coherent QPSK (quadrature phase-shift keying) signaling over frequency-nonselective Rayleigh fading channels, and in the presence of a single interferer. >
38 citations
TL;DR: A reconfigurable dual-channel all-optical logic gate is proposed and experimentally demonstrated using four-wave mixing in a silicon waveguide for polarization encoding signals.
Abstract: A reconfigurable dual-channel all-optical logic gate is proposed and experimentally demonstrated using four-wave mixing in a silicon waveguide for polarization encoding signals Six logic functions, XNOR, AND, NOR, XOR, AB¯, and A¯B are implemented at two different wavelength channels by adjusting the polarization states of two 10 Gb/s non-return-to-zero polarization-shift keying (NRZ-PolSK) signals modulated by 10-bit on–off keying (OOK) sequences The eye diagrams of the logic signals are clearly observed, and the logic functions are well demonstrated as the two incident NRZ-PolSK signals are both modulated by the OOK sequences, which originate from 231−1 pseudo-random binary sequences
38 citations
TL;DR: In this paper, the authors apply optical steganography to public differential phase-shift keying (DPSK) transmission by transmitting a stealth amplitude-modulated signal through a DPSK link.
Abstract: We propose to apply optical steganography to public differential phase-shift keying (DPSK) transmission by transmitting a stealth amplitude-modulated signal through a DPSK link. The secretly transmitted signal is temporally stretched with chirped fiber-Bragg gratings (CFBGs), and therefore, can be hidden under public DPSK signals. The stealth signal is successfully recovered and detected asynchronously, without clock synchronization with the transmitter.
37 citations
TL;DR: It is demonstrated that a few iterations are sufficient to approach the optimal ML detection performance obtained with the perfect channel state information.
Abstract: A low-complexity semi-blind joint channel estimation and data detection scheme is proposed for space-time shift keying (STSK) based multiple-input multiple-output systems. The minimum number of STSK training blocks, which is related to the number of transmitter antennas, is first utilized to provide a rough initial least square channel estimate (LSCE). Then low-complexity single-stream maximum likelihood (ML) data detection is carried out based on the initial LSCE and the detected data are employed to refine the decision-directed LSCE. It is demonstrated that a few iterations are sufficient to approach the optimal ML detection performance obtained with the perfect channel state information.
37 citations