http://hdl.handle.net/123456789/114 2026-07-16T13:07:20Z 2026-07-16T13:07:20Z Muhammad, Fazal Enroll # 02-281191-001 http://hdl.handle.net/123456789/21530 2026-07-16T05:53:20Z 2025-01-01T00:00:00Z

DESIGN OF MODULAR MULTILEVEL CONVERTER FOR ENHANCEMENT OF ELECTRICAL ENERGY EFFICIENCY IN SMART GRID SYSTEM Muhammad, Fazal Enroll # 02-281191-001 Power distribution networks frequently experience power quality issues due to transient voltage sag originating from the upstream grid. Voltage sag is one of the major concerns of modern industry, as it can interrupt sensitive electrical loads and in the worst case cause production problems. Various technologies are used to mitigate power quality issues due to transient voltage sag such as DVR, SVC, and UQPC but they increased the complexity and cost of the system. MMC is a state-of-the-art power electronics- based technology with outstanding features of power quality and low cost. The aim of this thesis is to explore the feasibility of the power quality conditioning system based on a back-to-back Modular Multilevel Converter (MMC) to overcome voltage sag and ensure satisfactory power delivery to the distribution network. In this thesis, an MMC is designed to mitigate voltage sag due to symmetrical and asymmetrical faults in the upstream AC grid using the integrated energy of its sub-modules. In addition, the designed MMC is highly scalable and reliable, having low harmonic distortion and reactive power support. The significant outcomes of the proposed MMC-based voltage sag mitigation are cross-referenced with the other methods adapted for voltage sag mitigation in the literature. The designed converter is also one of the best options for future DC grids due to its many advantages. The designed converter is fault-tolerant and meets the challenges of Fault Ride-through (FRT) capability to avoid short-term outages caused by faults in AC or DC networks. In this research, a Fault Ride-through (FRT) strategy is proposed by converting 10% redundant submodules to full-bridge submodules during a fault scenario. The proposed strategy is framed in conjunction with the DC circuit breaker to accomplish economically viable operations and respond quickly to the system during the pole-to-pole and pole-to-ground DC faults. It is concluded that the proposed FRT strategy is economically viable. Moreover, the power loss of semiconductor devices within the submodules of the designed MMC, losses of the IGBT module, and the free-wheeling diode are analyzed when the switching frequency, power factor (p.f) and modulation index of the system are changed. The power losses of MMC have been examined for the four-quadrant operations i.e. inverter (inductive), rectifier (inductive), rectifier (capacitive), and inverter (capacitive). The evaluation of the power losses has been carried out employing PLECS to examine the losses of the designed MMC. In addition, the power loss of the designed MMC is compared with the power loss of the other conventional MMCs. It is concluded that the power losses of the designed MMC are less than those of the other conventional MMCs. Finally, it is concluded that the contributions of this research can be used in many practical and industrial applications. In terms of industrial specifications, this research meets the power quality requirements of industrial load for its efficient and economical operation meeting power quality standards. It provides a FRT strategy that economically overcomes the short-term outages caused by faults in AC and DC distribution networks. It can also be used for HVDC Back-to-back systems operating in islanded mode. Supervised by Dr. Haroon Rasheed

2025-01-01T00:00:00Z Akhter, Muhammad Ovais Enroll # 02-281192-001 http://hdl.handle.net/123456789/21528 2026-07-16T05:50:12Z 2024-01-01T00:00:00Z

ULP POWER AMPLIFIER USING 65nm CMOS TECHNOLOGY Akhter, Muhammad Ovais Enroll # 02-281192-001 Power amplifier (PA) is the most power-hungry component of RF transceiver, portraying design issues. These include insufficient connectivity, power distribution, bandwidth, linearity and efficiency parameters that did not match system requirements. The primary challenge in a PA design is achieving higher efficiency while maintaining linearity over a bandwidth with wide range of output power levels. The power-added efficiency (PAE) is a figure-of-merit (FoM) that indicates how well the PA transfonns DC power to RF power. Designers have raised concerns about PA in the front-end of wireless radios because of the system's significant power consumption. There has been a lot of study on PA methods for optimizing PA efficiency. It is a challenging measure in the design of PAs for various low-power IEEE 802 wireless standards. The result to this study's primary concern and problem is this issue, that presents the design and optimization of two ultra-low power (ULP) PA architectures using 65-nm CMOS technology. The first part of the dissertation is ULP Doherty PA (DPA) architecture with fixed interstage capacitances. The main amplifier and the peaking amplifier have been designed and optimized with power divider & combiner models using equivalent lumped parameters. Due to 40 MHz narrowband communication (2.4 - 2.44 GHz ISM band), it offers fixed capacitances before the input-impedance stages, for a perfect impedance matching at both stages. The novel design shows 2.1mW ultra-low DC power consumption, 29.2% PAE, and 4 dBm Pl-dB compression point. The post-lay out simulations show an extremely high gain of 10.14 dB, very low input-insertion loss of- 11.9 dB, very strong drive current capability of 547pA & 663 p A for main & peaking PAs respectively. Impedance matching is acquired to achieve the desired harmonic suppression at the output of DPA design, the consequences are all in comparison to state-of-the-art PA architectures for ZigBee and similar devices under short-range and low-power IEEE 802.15.4 WPAN standards. The second part of dissertation is class-F architecture with ET supply biasing to increase efficiency of overall PA design. The ET consists of a pre amplifier before the envelope detector (ED) in a cascaded linear model, to increase efficiency and to reduce DC power consumption. The gate-to-drain feedback in the PA's two cascode cells, terminated as class-F, helps to improve linearity and reduce harmonic content in the input signal. The novel design meets the requirements of the IEEE 802.11 ah standard for long-range low power WLAN by using a DC power consumption of 3.75mW, a PAE of 37.1%, and an operating frequency in the unlicensed 915-931 MHz band in the United States. The chip layout size is reduced to just 0.13mm2 by the ET inductor-less supply bias design. Supervised by Dr. Aurangzeb Rashid Masud

2024-01-01T00:00:00Z Tanveer, Arshee Ahmed Enroll # 02-281171-001 http://hdl.handle.net/123456789/21529 2026-07-16T05:51:55Z 2024-01-01T00:00:00Z

MILLIMETER WAVE FOR VEHICULAR COMMUNICATION USING EFFICIENT CODING TECHNIQUE Tanveer, Arshee Ahmed Enroll # 02-281171-001 A promising technology for vehicular ad-Hoc Networks (VANETs) is Millimeter- wave (mmWave). mmWave is, however, susceptible to path loss and fading, which degrades system performance. Error-free data between Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) in the context of fading and mobility of vehicles calls for in-depth research. In addition to the above-mentioned limitations, challenging issues degrading the reliability of VANET are the problems of high penetration loss and blocking. To establish effective communication in mmWave networks in context of vehicles, a detailed understanding of the VANET communication channel is necessary, which differs significantly from those explored at frequencies lower than 6 GHz. When a vehicle’s speed exceeds 50 km/h, Doppler shifts can have adverse affects on the reliability of V2V communication. The transmission becomes impossible in VANET because of the increasing mobility of the nodes. This research presents three tractable channel models for VANET in which system performance degradation due to error is addressed. The operating frequency is 60 GHz. In the first model, concatenated Bose-Chaudhuri-Hocquenghem (BCH) and Alamouti Space-Time Block Coding (ASTBC) and coding are used. The two Bit Error Rate (BER) closed-form approximations, one for BCH in Rayleigh fading and the other for BCH with ASTBC, are obtained. Signal to Noise Ratio (SNR) and code rate are included in these expressions, which can be used to create VANET systems. The findings demonstrate that the BER obtained by concatenating ASTBC and BCH is 10"5 thus outperforming the traditional BER obtained by ASTBC expression. The code rate (127,36), (127,64) and (255,251) are used to evaluate the performance of the proposed expressions. The second model is designing a comprehensive tractable model for VANET over millimeter waves that combines Reed Solomon (RS) coding with Space-Time Block Coding (STBC). The closed-form approximations for BER of RS in the Addi tive White Gaussian Noise (AWGN) channel and Rayleigh fading are derived. The performance of RS closed-form expressions is compared with previous BER com putation approaches. The results shows that the BER lies between 10'7 to 10'6. Furthermore, the model’s performance has been compared with the current VANET communication systems, specifically the IEEE 802.11bd and 3GPP V2X communi cation systems. Results are comparable with V2X NR and demonstrate that our suggested approach works better than IEEE 802.11bd. As metrics for performance, throughput, Packet Error Rate (PER) and Packet Reception Ratio (PRR) are em ployed. The model has also been evaluated with vehicles moving at faster velocities. Further, the simulation and numerical findings show that the AWGN approxima tion for STBC-RS model outperforms Reed Solomon - Mary Phase Shift Keying (RS-MPSK) traditional system i.e. the achieving the BER of 1CT7. These derived expressions can be adopted in designing various VANET architectures targeting re liability in the network. The path loss and fading are reduced since the directivity of the transmitter has increased using beamforming. The analytical and numerical results are compared, demonstrating the accuracy of our closed-form expressions. In the third model, the impact of the Doppler shift using BCH and RS coding is also analyzed in VANET communication. Since Orthogonal Frequency Division Multiplexing (OFDM), which is highly susceptible to Doppler shift, is used by the IEEE 802.lip PHY layer. It is seen that the results of the suggested model surpass those of earlier models, including 802.lip. Considering there exhibits a strong dependence of 5G/6G communication on both the molecular composition of the medium and the transmission distance. The closed-form expressions of BER are simulated in the Terahertz (THz) channel. A detailed analysis of relative humidity dependency on code rate is conducted. Further, the relation between code rate and relative humidity is analyzed. The results are analyzed at different code rates. Moreover, we have compared our results with the performance of existing ASTBC technique in the THz channel. The results depict that the proposed model surpasses the behavior of the ASTBC equation in THz. The findings presented here are expected to pave the way for ultra-reliable vehicular communication networks Supervised by Dr. Haroon Rasheed

2024-01-01T00:00:00Z Hussain, Muhammad Reg # 02-281151-001 http://hdl.handle.net/123456789/21527 2026-07-16T05:48:34Z 2023-01-01T00:00:00Z

RESOURCE ALLOCATION AND OPTIMIZATION OF MULTI USER COMMUNICATION FOR NEXT GENERATION NETWORK Hussain, Muhammad Reg # 02-281151-001 Existing wii eless networks use orthogonal access that serves users as per the number of available resources. On the other hand, Next Generation Networks (NGNs) use the concept of non-orthogonality that serves multiple users on a single resource which consequently enhances device connectivity and spectral efficiency. Non-Orthogonal Multiple Access (NOMA) scheme employs power division multiple access which is sensitive to interferences and noises. This research presents a composite multiple access scheme that is developed by a combination of Power Domain NOMA (PD- NOMA) and Orthogonal Beamforming (OBF) to improve the spectral efficiency and reduce the interference between beams in the presence of Impulse Noise (IN). Furthermore, a novel IN mitigation and classification technique is presented using deep learning methods which efficiently minimizes the harmful effects of IN from PD-NOMA-based communication systems. This research can be divided into three phases. The first phase of the research encompasses a new composite multiple access scheme based on PD-NOMA and OBF for exchanging information between smart grid, smart meters (SMs), and other communication units in the presence of IN. In the proposed scheme a cell is divided into sectors and OBF is implemented between sectors to reduce inter beams interference using orthogonalization. Within these sectors, the PD-NOMA scheme is implemented to utilize maximum bandwidth with the help of the successive interference cancellation scheme. According to the simu lation and numerical findings, the proposed scheme offers a 3 Mbit/sec higher data rate and 0.24 Mbit/joule greater energy efficiency than the traditional orthogonal | i frequency division multiple access scheme, leading to better system performance in the case of 10 SMs/users in a sector of a cell. Another significant achievement of the pioposed scheme is that it does not cause inter beam interference and provides 17 Mbit/sec higher data rate by using OBF compared to conventional beamforming in the case of 60 SMs/users in 12 sectors of a cell. The second phase deals with the analysis of performance degradation of the link due to the IN-contaminated wireless channel. Statistical formation i.e. the Probability Density Function (PDF) and Cumulative Distribution Function (CDF) is formulated for the channel to estimate the effect of IN. Moreover, two closed-form expressions are derived i.e. instantaneous Signal to Noise Ratio (SNR) by using the PDF and CDF for IN-contaminated wireless channel and Bit Error Rate (BER) by using instantaneous SNR for IN-contaminated PD-NOMA-based system. Finally, in the last phase of the research, a novel IN mitigation and classification technique is presented using deep learning methods for PD-NOMA-based commu nication systems. The IN detection is performed by first identifying the IN occur rences using a Deep Neural Network (DNN) that learns statistical traits of noisy samples, followed by removal of the harmful effect of IN in the detected occurrences. Compared to the existing IN detection methods, the proposed DNN provided an en hanced BER performance. The proposed method is further tested for high and low IN and weak and strong IN occurrence probabilities. The proposed DNN method detected approximately 0.1 Mbits more true symbols out of 1 Mbits compared to conventional methods. The DNN identified high IN in the incoming noisy PD- NOMA symbols with an accuracy of 99% and low impulses with an accuracy of 87% respectively. Supervised by Dr. Haroon Rasheed

2023-01-01T00:00:00Z