22 research outputs found

    Techniques in secure chaos communication

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    In today's climate of increased criminal attacks on the privacy of personal or confidential data over digital communication systems, a more secure physical communication link is required. Chaotic signals which have bifurcation behavior (depending on some initial condition) can readily be exploited to enhance the security of communication systems. A chaotic generator produces disordered sequences that provide very good auto- and cross- correlation properties similar to those of random white noise. This would be an important feature in multiple access environments. These sequences are used to scramble data in spread spectrum systems as they can produce low co-channel interference, hence improve the system capacity and performance. The chaotic signal can be created from only a single mathematical relationship and is neither restricted in length nor is repetitive/ cyclic. On the other hand, with the progress in digital signal processing and digital hardware, there has been an increased interest in using adaptive algorithms to improve the performance of digital systems. Adaptive algorithms provide the system with the ability to self-adjust its coefficients according to the signal condition, and can be used with linear or non-linear systems; hence, they might find application in chaos communication. There has been a lot of literature that proposed the use of LMS adaptive algorithm in the communication arena for a variety of applications such as (but not limited to): channel estimation, channel equalization, demodulation, de-noising, and beamforming. In this thesis, we conducted a study on the application of chaos theory in communication systems as well as the application of adaptive algorithms in chaos communication. The First Part of the thesis tackled the application of chaos theory in com- munication. We examined different types of communication techniques utilizing chaos theory. In particular, we considered chaos shift keying (CSK) and mod- ified kind of logistic map. Then, we applied space-time processing and eigen- beamforming technique to enhance the performance of chaos communication. Following on, we conducted a study on CSK and Chaos-CDMA in conjunction with multi-carrier modulation (MCM) techniques such as OFDM (FFT/ IFFT) and wavelet-OFDM. In the Second Part of the thesis, we tried to apply adaptivity to chaos com- munication. Initially, we presented a study of multi-user detection utilizing an adaptive algorithm in a chaotic CDMA multi-user environment, followed by a study of adaptive beamforming and modified weight-vector adaptive beam- forming over CSK communication. At last, a study of modified time-varying adaptive filtering is presented and a conventional adaptive filtering technique is applied in chaotic signal environment. Twelve papers have been published during the PhD candidature, include two journal papers and ten refereed conference papers

    Proceedings of the Mobile Satellite Conference

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    A satellite-based mobile communications system provides voice and data communications to mobile users over a vast geographic area. The technical and service characteristics of mobile satellite systems (MSSs) are presented and form an in-depth view of the current MSS status at the system and subsystem levels. Major emphasis is placed on developments, current and future, in the following critical MSS technology areas: vehicle antennas, networking, modulation and coding, speech compression, channel characterization, space segment technology and MSS experiments. Also, the mobile satellite communications needs of government agencies are addressed, as is the MSS potential to fulfill them

    3G migration in Pakistan

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    The telecommunication industry in Pakistan has come a long way since the country\u27s independence in 1947. The initial era could be fairly termed as the PTCL (Pakistan Telecommunication Company Limited) monopoly, for it was the sole provider of all telecommunication services across the country. It was not until four decades later that the region embarked into the new world of wireless communication, hence ending the decades old PTCL monopoly. By the end of the late 1990\u27s, government support and international investment in the region opened new doors to innovation and better quality, low cost, healthy competition. Wireless licenses for the private sector in the telecommunication industry triggered a promising chain of events that resulted in a drastic change in the telecommunication infrastructure and service profile. The newly introduced wireless (GSM) technology received enormous support from all stakeholders (consumers, regulatory body, and market) and caused a vital boost in Pakistan\u27s economy. Numerous tangential elements had triggered this vital move in the history of telecommunications in Pakistan. Entrepreneurs intended to test the idea of global joint ventures in the East and hence the idea of international business became a reality. The technology had proven to be a great success in the West, while Pakistan\u27s telecom consumer had lived under the shadow of PTCL dominance for decades and needed more flexibility. At last the world was moving from wired to wireless! Analysts termed this move as the beginning of a new era. The investors, telecommunication businesses, and Pakistani treasury prospered. It was a win-win situation for all involved. The learning curve was steep for both operators and consumers but certainly improved over time. In essence, the principle of deploying the right technology in the right market at the right time led to this remarkable success. The industry today stands on the brink of a similar crossroads via transition from second generation to something beyond. With the partial success of 3G in Europe and the USA, the government has announced the release of three 3G licenses by mid 2009. This decision is not yet fully supported by all but still initiated parallel efforts by the operators and the vendors to integrate this next move into their existing infrastructure

    DRONE DELIVERY OF CBNRECy – DEW WEAPONS Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD)

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    Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD) is our sixth textbook in a series covering the world of UASs and UUVs. Our textbook takes on a whole new purview for UAS / CUAS/ UUV (drones) – how they can be used to deploy Weapons of Mass Destruction and Deception against CBRNE and civilian targets of opportunity. We are concerned with the future use of these inexpensive devices and their availability to maleficent actors. Our work suggests that UASs in air and underwater UUVs will be the future of military and civilian terrorist operations. UAS / UUVs can deliver a huge punch for a low investment and minimize human casualties.https://newprairiepress.org/ebooks/1046/thumbnail.jp

    Pulse shaping and sir-energy trade-off in chaos-based asynchronous DS-CDMA

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    We develop a general framework to assess the joint effect of pulse shaping and spreading sequence statistics on asynchronous DS-CDMA, which also allows pulse and sequence optimal design. For each pulse we also consider an implementation effort proportional to how much its energy is concentrated into a finite time interval. We are first able to show that, within the class of band-limited pulses, sine-shaped profile paired with i.i.d sequences are able to minimize Multiple Access Interference (MAI) but maximize implementation effort. We then introduce a family of pulses that generalizes raised cosine profiles and show that, leveraging on the possibility of jointly designing sequence statistics and pulse profile, they help addressing the trade-off between MAI and implementation effort

    Vulnerability assessment of modern ICT infrastructure from an information warfare perspective.

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    Ph. D. University of KwaZulu-Natal, Durban 2011.The overall objective of the study is to provide a vulnerability assessment of the mobile communications infrastructure to information warfare attacks; this study has a South African focus. The mobile infrastructure was selected as the infrastructure and mobile devices incorporate the majority of modern ICT technologies, namely social networking, wireless connectivity and mobility, mass storage, as well as the telecommunications elements. The objectives of the study are to: Propose a new information warfare model, and from this deduce a vulnerability assessment framework from the specific information warfare perspective. These are the guiding frameworks and model for the study. Gather information regarding threats and vulnerabilities, with particular focus on potential use in information warfare and relevance to South Africa. Establish the criticality of the mobile infrastructure in South Africa. Use the gathered information in the vulnerability assessment, to assess the vulnerability of the mobile infrastructure and related devices and services. The model and framework are generated through desk-based research. The information is gathered from research protocols that are relevant to both research and risk and vulnerability assessment, these include: expert input through interviews and a research workshop, incident and trend analyses through news and vendor reports and academic publishing, computer simulation, questionnaire survey, and mathematical analyses. The information is then triangulated by using it in the vulnerability assessment. The primary and secondary data shows that attacks on confidentiality are the most prevalent for both computer-based networks and the mobile infrastructure. An increase in threats and incidents for both computer and mobile platforms is being seen. The information security trends in South Africa indicate that the existing security concerns are likely to worsen, in particular the high infection rates. The research indicates that the mobile infrastructure is critical in South Africa. The study validates the proposed framework, which indicates that South Africa is vulnerable to an information warfare attack in general. Key aspects of vulnerability in the mobile infrastructure are highlighted; the apparent high load of the mobile infrastructure in South Africa can be seen as a high risk vulnerability. Suggestions to mitigate vulnerabilities and threats are provided

    European Information Technology Observatory 1995

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