Browsing by Author "Lukman A, Olawoyin"
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Item Economics of Dynamic Spectrum Access(Faculty of CIS, University of Ilorin, Nigeria, 2017-05) Lukman A, Olawoyin; Oloyede, Abdulkarim A; Faruk, Nasir; Adediran, Yinusa ADynamic Spectrum Access (DSA) was introduced to enhance spectral efficiency as a result of increasing demand for the use of the radio spectrum and to combat the inefficiencies associated with static spectrum allocation. However, it is envisaged that the DSA would result in a drop in revenue, increase in operational costs and could leads to congestion of the network as a result of interference imposed due to secondary usage of the spectrum. Moreover, there is also a need to reduce the energy consumption of the system which could combat the climate change. This therefore, necessitates, the need to examine the social-economic aspect of the DSA systems. The paper investigates the appropriateness of an auction process in DSA networks. Game theory was used to propose a model that helps solving the pricing challenges expected of an auction-based DSA network. The results presented show that, if properly implemented, the DSA can help in congestion management, increase in revenue generation, decrease in operational costs and reduction in in energy consumption.Item Path Loss Predictions in the VHF and UHF Bands Within Urban Environments: Experimental Investigation of Empirical, Heuristics and Geospatial Models(Institute of Electrical and Electronics Engineers, 2019-06-01) Nasir, Faruk; Segun, Popoola; Bakinde, Surajudeen; Abdulkarim, Oloyede; Lukman A, Olawoyin; Mudathir, Akorede; Adulkader, Madugu; J.D, Morrow; Yinusa, AdediranDeep knowledge of how radio waves behave in a practical wireless channel is required for effective planning and deployment of radio access networks in urban environments. Empirical propagation models are popular for their simplicity, but they are prone to introduce high prediction errors. Different heuristic methods and geospatial approaches have been developed to further reduce path loss prediction error. However, the efficacy of these new techniques in built-up areas should be experimentally verified. In this paper, the efficiencies of empirical, heuristic, and geospatial methods for signal fading predictions in the very high frequency (VHF) and ultra-high frequency (UHF) bands in typical urban environments are evaluated and analyzed. Electromagnetic field strength measurements are performed at different test locations within four selected cities in Nigeria. The data collected are used to develop path loss models based on artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and Kriging techniques. The prediction results of the developed models are compared with those of selected empirical models and field measured data. Apart from Egli and ECC-33, the root mean squared error (RMSE) produced by all other models under investigation are considered acceptable. Specifically, the ANN and ANFIS models yielded the lowest prediction errors. However, the empirical models have the lowest standard deviation errors across all the bands. The findings of this study will help radio network engineers to achieve efficient radio coverage estimation; determine the optimal base station location; make a proper frequency allocation; select the most suitable antenna; and perform interference feasibility studies.Item Reliability Study of Stand-alone Hybrid Renewable Energy Microgrids(Iran J Sci Technol Trans Electr Eng, 2018-10-18) Bakinde, Surajudeen; Faruk, Nasir; Segun, Popoola; Muhammad, Salman; Abdulkarim, Oloyede; Lukman A, Olawoyin; C.T, CalafateThis paper proposed new indices for investigating the reliability of the microgrid at different levels. The microgrid used has been developed in DigSILENT software and is comprised of wind, solar, battery storage and a diesel generator. The software was used to observe the effect of system demand and the failure rate of each component at three indices levels. Different simulations had shown that an increase in the system demand affects average energy not supplied, EIC, and average customer curtailment index. Also, at load point, LPIC and load point energy not supply among others are sensitive to system demand. This work proposes a new approach to study the effect of network structure on the reliability of a microgrid. The proposed method employs the prioritization of component importance on microgrid configuration. The results obtained show that the contribution of components to the system’s reliability depends on the network structure. This could be used in identifying direction, priority, and upgrading and suggests the most efficient way to operate and maintain a microgrid.Item Secure transmission in an unfriendly environment(Published by Elsevier BV, 2019-10-01) Lukman A, Olawoyin; Faruk, Nasir; Abdulkarim, Oloyede; Segun, Popoola; Temitayo, Adeniran; Bakinde, Surajudeen; Abdulkarim, AbubakarThis work investigates and show the performance of destination assisted node in ensuring secure communication in a dual-hop broadcast system. The information transmission occurs between the transmitters which are assumed to be equipped with single antenna through a number of intermediate untrusted relays to the receiver in the presence of multiple passive eavesdroppers. This work assumes that there is no direct link between the transmitter and the receiver and hence, the relay node, receives either the information or noise signal at every transmission processes. Since the transmission occurs in a two-phase, the legitimate receiver is contributing a degrading noise to both the eavesdropper and relay node channels during the first phase while it receives information from the transmitter through the relay during the second phase. Simulation results are used to illustrate the performance of the proposed scheme.