Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol

Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol

Introduction to Random Signals and Noise

Random signals and noise are present in many engineering systems and networks. Signal processing techniques allow engineers to distinguish between useful signals in audio, video or communication equipment, and interference, which disturbs the desired signal. With a strong mathematical grounding, this text provides a clear introduction to the fundamentals of stochastic processes and their practical applications to random signals and noise. With worked examples, problems, and detailed appendices, Introduction to Random Signals and Noise gives the reader the knowledge to design optimum systems for effectively coping with unwanted signals.\ud \ud Key features:\ud • Considers a wide range of signals and noise, including analogue, discrete-time and bandpass signals in both time and frequency domains.\ud • Analyses the basics of digital signal detection using matched filtering, signal space representation and correlation receiver.\ud • Examines optimal filtering methods and their consequences.\ud • Presents a detailed discussion of the topic of Poisson processed and shot noise.\u

Approaching the ultimate capacity limit in deep-space optical communication

The information capacity of an optical channel under power constraints is ultimately limited by the quantum nature of transmitted signals. We discuss currently available and emerging photonic technologies whose combination can be shown theoretically to enable nearly quantum-limited operation of a noisy optical communication link in the photon-starved regime, with the information rate scaling linearly in the detected signal power. The key ingredients are quantum pulse gating to facilitate mode selectivity, photon-number-resolved direct detection, and a photon-efficient high-order modulation format such as pulse position modulation, frequency shift keying, or binary phase shift keyed Hadamard words decoded optically using structured receivers.Comment: 9 pages, 4 figures. Presented at Free-Space Laser Communications XXXI, 4-6 February 2019, San Francisco, C

Transmit Diversity Assisted Space Shift Keying for Colocated and Distributed/Cooperative MIMO Elements

Space Shift Keying (SSK) modulation is a recently proposed MIMO technique, which activates only a single transmit antenna during each time slot and uses the specific index of the activated transmit antenna to implicitly convey information. Activating a single antenna is beneficial in terms of eliminating the inter-channel interference, and mitigates the peak-to-mean power ratio, while avoiding the need for synchronisation among transmit antennas. However, this benefit is achieved at a sacrifice, since the transmit diversity gain potential of the multiple transmit antennas is not fully exploited in existing SSK assisted systems. Furthermore, a high SSK throughput requires the transmitter to employ a high number of transmit antennas, which is not always practical. Hence, we propose four algorithms, namely open-loop Space Time Space Shift Keying (ST-SSK), closed-loop feedback-aided phase rotation, feedback-aided power allocation, and cooperative ST-SSK, for the sake of achieving a diversity gain. The performance improvements of the proposed schemes are demonstrated by Monte-Carlo simulations for spatially independent Rayleigh fading channels. Their robustness against channel estimation errors is also considered. We advocate the proposed ST-SSK techniques, which are capable of achieving a transmit diversity gain of about 10 dB at a BER of 10-5, at a cost of imposing a moderate throughput loss dedicated to a modest feedback overhead. Furthermore, our proposed ST-SSK scheme lends itself to efficient communication, because the deleterious effects of deep shadow fading no longer impose spatial correlation on the signals received by the antennas, which cannot be readily avoided by co-located antenna elements

Retrodirective transponder feasibility experiment

Test program on feasibility of digital phase measuring subsystem of pulse-coherent retrodirective transponde

Adaptive Subcarrier PSK Intensity Modulation in Free Space Optical Systems

We propose an adaptive transmission technique for free space optical (FSO) systems, operating in atmospheric turbulence and employing subcarrier phase shift keying (S-PSK) intensity modulation. Exploiting the constant envelope characteristics of S-PSK, the proposed technique offers efficient utilization of the FSO channel capacity by adapting the modulation order of S-PSK, according to the instantaneous state of turbulence induced fading and a pre-defined bit error rate (BER) requirement. Novel expressions for the spectral efficiency and average BER of the proposed adaptive FSO system are presented and performance investigations under various turbulence conditions and target BER requirements are carried out. Numerical results indicate that significant spectral efficiency gains are offered without increasing the transmitted average optical power or sacrificing BER requirements, in moderate-to-strong turbulence conditions. Furthermore, the proposed variable rate transmission technique is applied to multiple input multiple output (MIMO) FSO systems, providing additional improvement in the achieved spectral efficiency as the number of the transmit and/or receive apertures increases.Comment: Submitted To IEEE Transactions On Communication