M-ary differential phase shift keying with non-coherent detection in mobile channels

In this thesis the system performances of M-ary differential phase shift keying (DPSK) with limiter discriminator detector (LDD) and differential phase detector (DPD) are investigated. The average error probability for DPSK-LDD and DPSK-DPD is evaluated in the additive white Gaussian noise (AWGN) channel and fading channels which include the satellite mobile channel (Rician) and the land mobile channel (Rayleigh). The systems analysed in this thesis are narrow-band systems which use Nyquist filters as the system filters. The time domain representation of the signal is derived for the system. Non-coherent detection methods; limiter discrimination detection and differential phase detection are analysed. In the DPSK-LDD system there is intersymbol interference (ISI) at the optimum sampling time. We can use the roll-off (3 of the Nyquist filter to reduce the effect of ISI by increasing the value of (3. Expressions for the error probability of DPSK-LDD and DPSK-DPD are derived. The average error probability for binary, quaternary and octal symbols is computed as a function of various parameters such as energy to noise ratio, time delay, Doppler frequency shift and roll-off (3 of the Nyquist filters. In the DPSK-LDD system the best sampling time has a shift of T/2 (T is the symbol duration) from the point at which DPSK-DPD samples are optimal. The error probability for DPSK-LDD fluctuates against time delay for small value of the time delay while for DPSK-DPD it increases with time delay. In the presence of Doppler frequency shift the DPSK-LDD system performs better than the DPSK-DPD system. In the absence of Doppler frequency shift the DPSK-DPD system gives a lower error probability than the DPSK-LDD system. The error probability for both DPSK-LDD and DPSK-DPD decreases with increasing K (the ratio of energy in specular and diffuse components), energy to noise ratio and (3 and the error probability increases with increasing Doppler frequency shift and the number of symbols

Application of systems engineering to complex systems and system of systems

2017 Spring.Includes bibliographical references.This dissertation is an investigation of system of systems (SoS). It begins with an analysis to define, with some rigor, the similarities and differences between complex systems and SoS. With this foundation, the baseline concept is development for several different types of systems and they are used as a practical approach to compare and contrast complex systems versus SoS. The method is to use a progression from simple to more complex systems. Specifically, a pico hydro electric power generation system, a hybrid renewable electric power generation system, a LEO satellites system, and Molniya orbit satellite system are investigated. In each of these examples, systems engineering methods are applied for the development of a baseline solution. While these examples are complex, they do not rise to the level of a SoS. In contrast, a multi-spectral drone detection system for protection of airports is investigated and a baseline concept for it is generated. The baseline is shown to meet the minimum requirements to be considered a SoS. The system combines multiple sensor types to distinguish drones as targets. The characteristics of the drone detection system which make it a SoS are discussed. Since emergence is considered by some to be a characteristic of a SoS, it is investigated. A solution to the problem of determining if system properties are emergent is presented and necessary and sufficient conditions for emergence are developed. Finally, this work concludes with a summary and suggestions for additional work