Keying

About: Keying is a research topic. Over the lifetime, 6598 publications have been published within this topic receiving 82943 citations.

Performance Analysis of Decode-and-Forward Multi-Hop Communication: A Difference Equation Approach

Abstract: The performance of decode-and-forward multi-hop communication is analyzed in a Rayleigh fading environment. Analytical expressions for the end-to-end symbol error probability are derived in the cases of M-ary phase-shift keying with coherent detection and orthogonal M-ary frequency-shift keying with non-coherent detection using a difference equation approach. When the path loss exponent is greater than one, each node transmits with the same power as that of a direct transmission source, and the relays are equispaced along the line joining the source and the destination, the performance improves with increasing number of hops. Furthermore, for fixed average signal-to-noise ratio per hop, the incremental degradation in performance when adding more hops decreases with each extra hop.

Layered Multi-Group Steered Space-Time Shift-Keying for Millimeter-Wave Communications

Abstract: We propose a novel multi-user multiple-input multiple-output (MIMO) technique termed the layered multi-group steered space-time shift keying (LMG-SSTSK) for the downlink of millimeter wave (mmWave) communications, which combines the concepts of multi-user MIMO, space-time shift keying, beamforming and orthogonal frequency-division multiplexing to simultaneously convey information to multiple users. The LMG-SSTSK tackles the propagation challenges of the high-attenuation mmWave frequencies by sub-dividing the users into multiple groups. The proposed system allows more users to be served simultaneously in the downlink over the same time- and frequency-resources than a system dispensing with the proposed grouping technique.

Multitone frequency-hopped MFSK system for mobile radio

Abstract: A digital spread spectrum technique employing frequency hopping and multilevel frequency-shift keying has recently been examined for possible application in mobile radiotelephony. Two system parameters, the number of bits per message and the number of tones in the frequency-hopping sequence, are determined by the available bandwidth and the data rate of each user. These parameters in turn determine the tone duration, which strongly influences the vulnerability of the system to transmission distortions. In this paper we describe a generalization of the MFSK scheme that allows users to transmit more than one tone simultaneously. Multitone transmission makes it possible for designers to increase the duration of each tone by increasing the total number of system frequencies. This flexibility slightly increases maximum efficiency and makes the system less vulnerable to multipath delay spread. It could also have implementation advantages.

Chip Averaging Chaotic ON–OFF Keying: A New Non-Coherent Modulation for Ultra Wide Band Direct Chaotic Communication

Abstract: This letter proposes a new adaptive threshold modulation scheme, called chip averaging chaotic ON–OFF keying (CA-COOK). This new scheme is applied to non-coherent modulations in ultra-wideband direct chaotic communication. Mainly, the proposed method deals with the “estimation problem” caused by the bit energy variation of the chaotic carrier signal. This is completed by adopting the Cell Averaging Constant False Alarm Rate paradigm used in radar, and each bit period is divided into several chips, where one of those chips is bearing the information. Bit-error-rate performance in additive-white-Gaussian-noise, two-path Rayleigh, and IEEE802.15.4a office NLOS channel models, is analyzed and compared with well-known and challenging chaos-based communication systems. Simulation results show the effectiveness of the proposed CA-COOK.

Optical communication system using correlation receiver

Abstract: The present invention provides for a system and method for an optical communication system that utilizes an optical modulator as an optical correlator in a receiver. The present invention may be used as a correlator in a receiver for an On-Off Keying (OOK) system or for a Differential Phase Shift Keying (DPSK) system. A correlation modulator is followed by a low pass filter, which together act as a correlator to determine the correlation of the received waveform with possible transmitted waveforms to produce a maximized signal-noise ratio. The result is a high data rate communication system and method that approaches the theoretical performance limit.