Yazar "Ali, Muhammad" seçeneğine göre listele

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    Analysis of interconnected configuration for penetration of distributed generation
    (Accent Social and Welfare Society, 2021) Farooqi, Bilal Asghar; Ahmad, Mohamad Radzi Bin; Ali, Muhammad
    This paper visualizes the feasibility of the proposed interconnected distributed power system configuration, which aims at incorporating the electricity generation from renewables and to cater to low voltage areas of radial distribution network. The shortcoming of existing traditional radial systems is inconsistent load distribution and technical viability in incorporating renewable sources without disturbing the power system. Sustainable development is achieved with improvement in the prevailing distribution system. Maximum potential benefits in terms of demand-supply balance and integrating renewables can be achieved by selecting properly placed and optimally sized distributed generation sources in a distribution network. The generation facility is selected as per the geographical profile of the location and placed on the weakest node. The weakest node is the low voltage profile region where the maximum output of the integration of power sources is beneficial. In this paper, the ZIP model-based methodology is applied to feeder loads on the data set of the distribution grid of the National University of Science & Technology (NUST), Islamabad, Pakistan. The comparative analysis is performed on a radial network of NUST distribution grid and compared with a simulated interconnected distribution system of the same distribution network on MATLAB software as a case study to observe the performance of interconnected power systems. This analysis results in better voltage profiles for interconnected networks, compared to radial networks. That said, incorporating a Distributed Generation (DG) source in the interconnected network builds a substantial impact on the distribution system voltage profile. The efficacy of the proposed interconnected system confirms the performance improvement of the distribution power system. The VSI values for interconnected systems give better results which is further justified by the machine learning algorithm, Logistic regression. The simulation results indicate that the Interconnected system encourages penetrations of solar, wind, gas turbine, and other renewable sources near the low voltage end in the distribution system. © 2021 Bilal Asghar Farooqi et al.
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    Downlink Performance Evaluation of NOMA Systems Based on Different OFDM Waveforms
    (IEEE, 2019) Kabalci, Yasin; Ali, Muhammad
    Non-orthogonal multiple access (NOMA) schemes have emerged as an inspiring technology for next generation mobile communication systems. This paper firstly confirms the superiority of NOMA systems over orthogonal multiple access (OMA) schemes by considering orthogonal frequency division modulation (OFDM) waveform. Further, it is verified that coded NOMA systems based on low-density parity-check (LDPC) coding outperform uncoded NOMA systems in terms of bit error rate (BER) performance metric with respect to transmit power. To show the performance of OMA and NOMA systems, two cells each having a single base station (BS) are constructed. For simplicity, two devices are considered in OMA cell while four devices are used in NOMA cell which utilize multiple user superposition transmission (MUST) technique (downlink power-domain version of NOMA). Later, performance of the system is analyzed in terms of throughput and peak-to-average power ratio (PAPR) for downlink scenario. Lastly, performance of the considered system for different waveforms such as OFDM, weighted over lap and add (WOLA) and filtered OFDM (F-OFDM) is compared. According to obtained simulation results, WOLA waveform generally outperforms OFDM and F-OFDM waveforms in throughput, however, slight better results are being shown by F-OFDM waveform in high PAPR values.
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    Emerging LPWAN Technologies for Smart Environments: An Outlook
    (IEEE, 2019) Kabalci, Yasin; Ali, Muhammad
    Low-power wide-area network (LPWAN) technologies are emerging communication systems that aim to present a new concept supporting wide area communication with low power requirements for smart environments such as smart grids (SGs), smart cities, smart meters (SMs) and Internet of Things (IoT). This study presents a systematical analysis for popular LPWAN technologies such as Ultra Narrowband (UNB), Long Range (LoRa), Long Term Evolution for Machines (LTE-M) and Narrow Band IoT (NB-IoT). Technical structures, advantages and drawbacks of these communication technologies are detailed examined by considering their operating spectrum, where UNB and LoRa technologies operate on unlicensed spectrum while LTE-M and NB-IoT technologies work on licensed spectrum. Consequently, it is shown that it is not yet clear which one of these technologies will be winner since there currently exist several challenges to be solved such as battery life, capacity and cost.
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    Energy Internet: A Novel Vision for Next-Generation Smart Grid Communications
    (IEEE, 2019) Kabalci, Yasin; Ali, Muhammad
    Energy Internet (EI) is a novel concept that can be thought of transformation of smart grids into the Internet where different energy forms can be integrated to provide more efficient and resilient power grid. Deployment of modern communication techniques are expected to serve as backbone for EI. However, designing advanced and robust communication infrastructures for enabling effective EI systems is a very critical and complex task. The key aim of this study is to provide an analysis to address present status of EI systems. Firstly, the key idea of EI systems along with its essential components is presented. Later on, latest developments in energy routers, information and network systems that are essential for concept of EI are discussed. At last, the threats and their possible solutions subjected to the EI systems are discussed.
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    Improved Hybrid Precoder Design for Secure mmWave MIMO Communications
    (Kaunas Univ Technology, 2020) Kabalci, Yasin; Ali, Muhammad
    Key challenges of emerging mobile communication systems are to provide higher data rates, diverse device connectivity, low latency, higher system capacity, and low energy consumption. The communication systems exploiting the millimeter-wave (mmWave) band are realized to resolve thereof inevitable issues. However, security is considered as one of the challenging issues in mmWave communication in addition to unavoidable problems (e.g., propagation loss, penetration loss, and fading). This study aims to construct efficient secure hybrid precoder with low-resolution phase shifters that can protect legitimate information from eavesdropping by employing coordinated analog precoder and combiner algorithms and improve the secrecy rate. Moreover, in order to further enhance the secrecy rate, hybrid precoder are obtained using an efficient channel. This work compares its results with the recent approach reported in the literature, which indicates that our proposed model outperforms at high signal-to-noise ratio (SNR) values, while our model provides similar performance at low SNR values. Simulation studies also confirm the effectiveness of the proposed hybrid precoder to achieve maximum secrecy rate.
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    Investigation of Inter-User Interference Effect on 5G Uplink Communications
    (IEEE, 2019) Kabalci, Yasin; Ali, Muhammad
    Manifold connected devices are expected in Fifth Generation (5G) wireless communication systems that may lead to serious interference issues among the User Equipments (UEs). This inter-user(s) interference certainly degrade the performance of devices in terms of Bit Error Rate (BER) and throughput. This paper investigates the impact of different modulation waveforms such as Orthogonal Frequency Division Modulation (OFDM), Filtered OFDM (F-OFDM) and Filtered Bank Multiple Carrier (FBMC) on the performance of devices in 5G uplink communications and sorts out which waveform provides optimal results in the presence of inter-user interference. To analyze the effect of inter-user interference, a general model is constructed consists of two cells each having single UE and a Base Station (BS) for simplicity. Pedestrian A channel model is chosen in this study, whereas Low-Density Polarity-Check (LDPC) coding scheme is considered for channel coding for all the considered waveforms. The performance of the system in terms of BER, throughput and Peak-to-Average Power Ratio (PAPR) for the aforementioned waveforms are analyzed through simulation studies. According to simulation results, FBMC waveform generally outperforms OFDM and F-OFDM in all the performance metrics (i.e., BER, throughput and PAPR).
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    Iterative geometric mean decomposition based secure hybrid precoder design for mmWave massive MIMO communication systems
    (Elsevier Gmbh, 2021) Kabalci, Yasin; Ali, Muhammad
    Physical layer security (PLS) is one of the major concerns in modern mobile communication systems and has got special attention in millimeter-wave (mmWave) communication systems. The principal objective of this study is to construct a hybrid precoder that can secure the mmWave communication systems by incorporating the finest techniques to obtain a secure precoder and combiner for the legitimate receiver and to ensure minimum information leakage towards illegal-user. In this context, firstly, a traditionally coordinated precoder and combiner design algorithm is exploited in the analog domain to protect the legitimate receiver, and then, iterative geometric mean decompositions (IGMD) scheme is applied to obtain a digital precoder and combiner. Moreover, artificial noise (AN) is also transmitted towards illegal-user that further alleviates the privacy of the system. Finally, we compared our results with our latest proposed algorithm for a secure hybrid precoder system based on the generalized triangular decomposition (GTD) method and a recent algorithm presented in the literature. The simulation studies confirmed that the IGMD based approach considerably degrades the eavesdropping capabilities of the undesired user and provides significantly better secrecy rate performance as much as 3.5 bps/Hz than its counterparts.
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    Optimal hybrid precoder design for millimeter-wave massive MIMO systems
    (Pergamon-Elsevier Science Ltd, 2022) Kabalci, Yasin; Ahmadi, Mustafa; Ali, Muhammad
    Millimeter-waves (mmWave) have emerged as a promising candidate for next-generation communication systems. However, they have severe degradation issues that can be overcome by multiple-input multiple-output (MIMO) technology. Still, high-power consumption and budget issues are associated with multiple antennas. Therefore, hybrid precoders are exploited to combat these inevitable issues. The prime objective of this manuscript is to develop a hybrid precoder for massive MIMO systems that can provide better performance than the existing ones in terms of bit error rate (BER) versus signal-to-noise ratio (SNR). In this context, we exploit iterative geometric mean decomposition (IGMD) method that presents asymptotically optimum performance not only in traditional MIMO systems but also in massive MIMO systems. Later, the outcomes of the proposed scheme are compared with a recent design exploiting generalized triangular decomposition (GTD) scheme. The simulation studies show that the proposed method provides more than 7 dB improvement according to other designs.
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    Performance Assessment of Hybrid Precoders in the Presence of Artificial Noise
    (IEEE, 2020) Kabalci, Yasin; Ali, Muhammad
    The demands of users are gradually increasing with the passage of time and with the continuous evaluation in wireless communication technology (i.e., from first to fifth-generation (1G to 5G)). To acquire extreme capacity, extra-high data rates, massive connectivity, extremely low latency and energy consumption, the utilization of a suitable frequency band of the electromagnetic spectrum is inevitable. An appropriate solution is to utilize millimeter-waves (mmWaves) that can offer 200 times more bandwidth than the existing technology to meet the growing demands of applicants. However, these waves have certain degradation problems, which can be solved by deploying multiple-antenna technology owning to short wavelengths offered by mmWave bands. Still, security is one of the major problems associated with the mmWaves and has got a lot of attention from the researchers in recent times. The primary objectives of this study are to first present a secure hybrid precoder design in mmWave massive multiple-input multiple-output (MIMO) communication systems with the aid of artificial noise (AN), and then, compare the results with the most recent method in the literature. Extensive simulation studies confirm that the AN based hybrid precoder provides more secure communication than its counterpart in terms of secrecy rate versus signal-to-noise ratio (SNR).
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    Secrecy rate analysis of hybrid precoders for mmWave communication systems
    (Elsevier, 2020) Kabalci, Yasin; Ali, Muhammad
    Millimeter-wave (mmWave) communication systems are realized to play a key role in next-generation communication systems to achieve high data rate requirements, allowing manifold connected devices and efficient bandwidth utilization. Although mmWave communication has severe degradation problems, security is considered as one of the most important issues. The objective of this study is to analyze and compare the effectiveness of secure communication among the transmitter, legitimate receiver and illegal user using different hybrid precoding and combining algorithms (phase extraction alternate minimizing (PE-AltMin), manifold optimization (MO-AltMin), spatially sparse precoding (SSP) and most recent reported algorithm in the literature). In this study, standard PE-AltMin and MO-AltMin algorithms are also modified in digital baseband domain to achieve better results. The security is achieved in two steps. First, cooperative analog precoder and combiner design algorithms are utilized to get RF precoder and combiner, and then, digital precoder and combiner are attained based on effective baseband digital channel. The simulation studies validate the impact of modified PE-AltMin algorithm that realizes better secrecy rate results than the other hybrid algorithms and ensures the most protected transmission. In simpler words, the utilization of proposed PE-AltMin hybrid algorithm offers the least information leakage towards Eavesdropper than others. (c) 2020 Elsevier B.V. All rights reserved.
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    Secured Hybrid Precoder Design Based on Generalized Triangular Decomposition Method
    (IEEE, 2020) Kabalci, Yasin; Ali, Muhammad
    The researchers and scientists suggest the use of millimeter-waves (mmWaves) for upcoming communication systems that can provide 200 times more bandwidth than the existing technology to meet all the challenging demands of modern mobile users. Since the demands of mobile users are exponentially increasing with the passage of time, exploiting the upper part of electromagnetic spectrum become vital to attain high data rate, broadband device connectivity, extreme capacity and nominal latency for upcoming communication systems. However, certain degradation problems are realized by the higher frequency bands. Thanks to the shorter wavelengths of mmWaves, which allow the employment of multiple-antenna technology to generate narrow and directed beam, and enhance the propagation gain. Still security is considered as one of the primary issues and has got lot of attention from the researchers in the recent times. In this study we aim to develop a hybrid precoder design that can ensure secure mmWave massive multiple-input multiple-output (MIMO) communications by exploiting generalized triangular decomposition (GTD) method in digital domain. Our simulation studies also confirms the effectiveness of GTD scheme.
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    Throughput Analysis over 5G NR Physical Uplink Shared Channels
    (IEEE, 2020) Kabalci, Yasin; Ali, Muhammad
    The high throughput with low latency, massively connected devices, and effective utilization of spectrum for current wireless communication systems can be realized by adopting the fifth-generation (5G) new radio (NR) air interface. The key remarkable features that 5G NR presents are Ultra-Reliable Low-Latency Communications (URLLC), enhanced Mobile Broadband (eMBB), and massive Machine Type Communications (mMTC). To meet thereof features, 5G NR exerts different multiple access and modulation techniques. This paper addresses the physical layer of 5G NR and more explicitly explores the transmission of 5G NR over the physical uplink shared channel (PUSCH) considering several parameters. For example, different sub-carrier spacings (SCSs) are taken into account for analyzing the performance of PUSCH in terms of throughput versus Signal-to-Noise Ratio (SNR). Moreover, the effect of the well-known modulation techniques such as Quadrature Phase Shift Keying (QPSK), different order of Quadrature Amplitude Modulation (QAM) (i.e., 16, 64, and 256) on throughput is studied. Later on, the number of base station (BS) and user equipment (UE) antennas are varied. Lastly, the performance of PUSCH over different propagation channel models (clustered delay line (CDL) and tap delay line (TDL)) is also investigated in this paper. The extensive simulation studies have proved that QPSK exhibits finer outcomes in low SNR regions while 256-QAM shows remarkable results in high SNR regions. The maximum throughput can be realized even in low SNR regime if the number of BS antennas is increased. In addition, high throughput value can be attained by increasing SCS.