88 research outputs found
Paving the Path of LTE Toward 5G: Physical Layer Assurance and Operation in the Unlicensed Spectrum
No full textLong-Term Evolution (LTE) is the fourth generation (4G) wireless communications standard and its evolution is paving the path for the fifth generation (5G) technology. LTE is also considered for supporting public safety networks, Machine-to-Machine (M2M) communications, and many other applications. Hence, it is critical to ensure that the LTE system performs effectively even in harsh signaling environments. Unfortunately, LTE is vulnerable to intentional interference at the physical layer. We define the term LTE control channel spoofing, which refers to the case when an adversary sets a fake LTE-like base station (evolved NodeB or eNodeB) that transmits a partial or full LTE downlink frame to deceive LTE devices and hinder them from attaching to a real cell. Based on analyzing the initial cell selection process in the LTE specifications, we identify three different level of LTE control channel spoofing. We have built a testbed to demonstrate the feasibility of such an attack. The experimental results show that LTE control channel spoofing can cause permanent denial of service for LTE devices during the cell selection process. We propose effective mitigation techniques to enhance the immunity of LTE systems against all the three forms of LTE control channel spoofing, and ensure that it is secure and available when and where needed.
Moreover, the commercial success of LTE and the resulting growth in mobile data demand have motivated cellular network operators to strive for new innovations. LTE-Unlicensed has been recently proposed to allow cellular network operators to offload some of their data traffic by accessing the unlicensed 5 GHz frequency band. There are three variants of LTE-Unlicensed that have been proposed in the industry. These variants differ in their operational features, but they enhance the capacity of LTE and represent a big milestone in its evolution toward 5G. However, LTE-Unlicensed faces several challenges when operating in the 5 GHz bands, as this spectrum is mainly occupied by Wi-Fi and by various radar systems. Therefore, we analyze the algorithms proposed in the industry for the LTE-Unlicensed and Wi-Fi coexistence, and we develop a new spectrum sharing technique for the coexistence between LTE-Unlicensed and radar systems.
In order to analyze LTE-Unlicensed and Wi-Fi coexistence, we first explain the technical details of each of the three variants of LTE-Unlicensed, and we provide a comparative analysis of them in terms of their operational features. Then we develop an unbiased and objective evaluation of their proposed coexistence mechanisms with Wi-Fi systems, and numerically compare their performance.
In order to emphasize the need for developing a new spectrum sharing technique for the coexistence between LTE-Unlicensed and radar systems, we first present the different regulatory requirements for the 5 GHz unlicensed bands in several world regions, and we perform a comprehensive survey on the different radar types within the 5 GHz sub-bands. Then we develop a novel spectrum sharing technique based on chance-constrained stochastic optimization to allow the LTE-Unlicensed eNodeB to share the spectrum efficiently with a radar system. The optimization problem is formulated to guarantee the minimum performance criteria for the radar operation, and at the same time allows the LTE-Unlicensed eNodeB to control its transmit power to maximize the performance for the serving LTE-Unlicensed device. A mathematical model is used to transform the stochastic optimization problem into a deterministic one, and an exhaustive search is used to solve the resulting optimization problem. Due to the power control mechanism resulting from the proposed algorithm, numerical results show a significant reduction in the protection distance required between the radar and the LTE-Unlicensed network for the two to coexist, as the proposed algorithm can allow the two systems to operate effectively with a protection distance of only 3.95% of the one imposed by the regulations
Post-Quantum Cryptography
No full textIn this thesis work, I will be presenting the idea of quantum computing and technology, and the future of cryptography and how it will be affected by powerful quantum computers, and the impact of post-quantum cryptography on hardware and software scale. Moreover, what we have reached in this technology and problems we currently facing and their algorithmic solutions. In the first step, I focused on gaining some theoretical knowledge about quantum computers, as it is a new topic for me, the more I dive into this field, the more interesting it became. Following the first step, I went through cryptography and its algorithms, and what scientists and engineers have reached to have some security against the supercomputers, from the very beginning and the first cryptography algorithms to the post-quantum or AES 256. Here I started to reach the point to work on the third aspect, which is to code and apply quantum resistance cryptography. I will gain my practical knowledge, considering some experience and knowledge from my studies in the past couple of years in the university. The ultimate aim of this project was to demonstrate the impact of quantum technology on cryptography, to develop a safe cryptosystem, this project was achieved by properly understanding the principles like cryptography, cryptosystems, quantum mechanics, qubits, AES, encryption, and decryption, hardware evaluation, etc.BSc/BAComputer science engineering BS
3D Finite element analysis of a scaled trapezoidal 3-story reinforced concrete structure on a shaking table
No full textThis master thesis is about finite element analyses of a 3D model of a 1/4th scaled trapezoidal 3-story reinforced concrete mock-up on a shaking table which is part of Smart 2013 international benchmark. The idea of this benchmark is to asses and predict the dynamic behavior of the reinforced concrete mock-up with respect to seismic loading using finite element method software. In this master thesis, the finite element method software Diana is used to asses and predict the dynamic behavior of the scaled mock-up with respect to seismic loading.Structural MechanicsStructural EngineeringCivil Engineering and Geoscience
A fundamental study on mechanical & physical properties of polymer-modified self-healing mortars using bacteria
No full textA polymer-modified self-healing mortar is a mixture of Portland cement, water, sand, polymer and self-healing material. The polyacrylic ester emulsion (PAE) is used as polymer and as self-healing material bacterial spores from genus Bacillus + calcium lactate is used. The reason why this type of bacteria is used as a component of self-healing material is because of the high alkaline environment inside the mortar. A mortar has a pH value of between 9 and 11. As far as known, only this kind of bacteria can be used as a self-healing agent for mortars. Why a polymer-modified self-healing mortar? This polymer- modified self-healing mortar has an autonomous self-healing mechanism with, a high workability, a high flexural strength and also a high adhision. The experiments that has been performed in this study show that a polymer- modified self-healing mortar is a strong material with and active self-healing. This bacterial self-healing mechanism can heal cracks up to 0.46mm in contrast to the autogenous self-healing (of conventional mortar) of cracks up to 0.18mm. Beside this the fresh mortar showed a high workability. These properties make the polymer-modified self-healing mortar a strong and a more durable mortar. This concept can also be used to produce polymer-modified self-healing concrete.Materials and EnvironmentCivil Engineering and Geoscience
Essay : The hologenome theory of evolution
No full textDe begeleider en/of auteur heeft geen toestemming gegeven tot het openbaar maken van de scriptie.
The supervisor and/or the author did not authorize public publication of the thesis.
Research Report 2 : Analysis of replication stress in genomically instable cancers
No full textDe begeleider en/of auteur heeft geen toestemming gegeven tot het openbaar maken van de scriptie.
The supervisor and/or the author did not authorize public publication of the thesis.
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