M.Phil / MS
Permanent URI for this collectionhttps://repository.cuilahore.edu.pk/handle/123456789/42
This collection archives the complete set of theses produced by students of the COMSATS University Islamabad, Lahore Campus.
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Item Wavelet Transform Based Sparse Code Multiple(Publisher COMSATS University Islambad Lahore Campus, 2020) Muhammad Sajid Sarwar,; SP17-REE-010; Dr. Amjad Hussain, Assistant Profesor; LHR TP 5633Fifth Generation (5G) of wireless communications that incorporates very high data rates, massive connectivity and very low latency can be fundamental part of 4th Industrial revolution. As far as, physical layer is concerned, Multiple Access (MA) techniques are significant in accommodating users on frequency and time resources for an efficient spectrum utilization, least Multi-Access Interference (MAI) and greater throughput. 5G is transforming user access techniques from orthogonal to non-orthogonal resource sharing methods. Non-Orthogonal Multiple Access (NOMA) technique is the transmission of superimposed signal of multi-users on shared frequency band simultaneously instead of utilizing separate frequency & time slot for each user. NOMA is categoried into Power Domain (PD) NOMA & Code Domain (CD) NOMA. Sparse Code Multiple Access (SCMA), a type of CD-NOMA that facilitates greater user connectivity for 5G. SCMA utilizes sparse resource allocation and non-orthogonal three dimensional codebooks to increase spectrum efficiency. Superimposed encoded data of all users employs a complex receiver such as Message Passing Algorithm (MPA) to extract user specific signal. In this research work, MAI for overloaded SCMA will be examined and different signal processing techniques will be employed to reduce it. Multi-Carrier (MC) communication techniques such as Fast Fourier Transformed Orthogonal Frequency Division Multiplexing (FFT-OFDM) combined with SCMA are analysed in literature and offers satisfactory performance for wireless communications. Recently proposed MC modulation schemes such as Wavelet Transformed OFDM (WT-OFDM) remained relatively unexplored with reference to SCMA. WT provides better decomposition & reconstruction as compared to FFT which is helpful for interference mitigation in a signal. Therefore, Wavelet Transform (WT) is expected to improve Signal to Interference and Noise Ratio (SINR) for SCMA users. Simulation models of SCMA and MC-SCMA schemes are presented that utilize MPA receiver to decode data of all superimposed users and show that WT-SCMA is superior to FFT-SCMA in the context of BER performance. Analytical models are derived for SINR employing Maximal Ratio Combining (MRC) to examine MAI for a particular user in the SCMA/MC-SCMA systems. SINR comparison shows that WT-SCMA outperforms FFT-SCMA.Item Voltage And Frequency Regulation For Distribution(Publisher COMSATS University Islambad Lahore Campus, 2021) Muhammad Zubair; , SP17-REE-007; : Dr. Sobia Baig, Assistant Profesor [Supervisor]; LHR TP 5632Microgrids comprising the renewable energy resources are the new face of modern elec tricity infrastructure. These grids work autonomously, have their own control architecture and give support to the utility grid in case of any failure. Most of the energy resources in microgrids are renewable like solar, wind etc. These resources have an intermittent nature making the control architecture an essential tool for its better performance. The induction of excessive renewable resources in the utility grid causes serious stability problems as these resources have intermittent nature. Therefore, an efficient control system is the main priority in these types of grids. The control system that is designed for microgrids requires to control some important parameters like voltage and frequency, active/reactive power bal ancing, power flow etc. Regulation of voltage and frequency within its nominal values is the most important parameter that ensures the stability of microgrid. The disturbance in voltage and frequency occurs due to variation in both generation and load. A centralized control approach is adopted in this research work using classical PID con troller to tackle this problem of voltage and frequency regulation. An isolated microgrid model is integrated in a Simulink interface tool using solar, wind and battery as resources. The centralized PID controller is implemented on load bus bar of 0.4 KV. This PID con troller is then tuned with closed loop PID autotuner block in real time as load and gen eration of the isolated microgrid are not constant. A detailed comparison of simple PID and PID with autotuner block is done using the frequency and voltage response of both techniques in constant and varying load scenarios. Results and calculation of various pa rameters shows that the PID working with closed loop autotuner has better performance compared to the simple PID whose gains are calculated at the start using conventional technique like Ziegler-Nichols method. This is because the PID used with autotuner block has its gains updated by observing the real time response of the system whereas simple PID tries to tackle the constantly varying load conditions based on its initial gain values. The performance of control strategy is also observed using real site data of solar and wind for Nooriabad, a city of Sindh Province in PakistanItem Design And Implementation Of A Simulation Tool For(Publisher COMSATS University Islambad Lahore Campus, 2021) Ruqia Fatima,; SP17-REE-025; Dr. Mujtaba Jaffery, Assistant Profesor [Supervisor]Solar power is a feasible source of renewable energy. Solar cars are becoming alternatives to cleaner emissions in transportation sector. Therefore, this field is becoming of great interest for the researches. To develop, analyze and implement the system, a necessity of a simulation tool comes in front. A tool that can analyze the design of a mathematical model, associated with different electrical and mechanical components in a system, plays a vital role to study their characteristics. This project is about modeling of different components of a solar powered electric car mathematically, to evaluate the characteristics of various components of the solar car along with its capability of determining the overall performance. The basic components, which are the part of this project, are: solar panel, battery, traction motor, charge controller and speed controller. The simulation tool selected for the project is SIMULINK, a graphical programming tool used with MATLAB, for plotting the graphs to study the dynamic behavior of different subsystems. Finally, all the mathematical models of components used in the system are integrated together to represent a complete dynamic model of a solar car, which is tested for three different environmental conditions that include sunny day, partially cloudy day and mostly cloudy day. The performance of the system is observed under these conditions.