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1
Kodikara, Patabandi C. K. "Multimedia communications over 3G wireless communication systems". Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/844270/.
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This thesis addresses the transmission of video over third generation radio access networks. The first part of the thesis investigates the capabilities of Universal Terrestrial Radio Access Networks (UTRAN) in terms of the provision of multimedia communications. The error performance and traffic requirements of real-time video transmission over circuit switched and packet switched connections are examined. The effect of network parameter settings upon video performances is evaluated, and optimum radio bearer configurations for the transmission of video are derived. A method of estimating received video quality after transmission over error prone environments is developed. The quality estimation is based on a distortion model, which accurately models the overall distortion seen in decoder frame reconstruction. This includes quantisation distortion, concealment distortion, and error propagation. Based on the developed performance model, optimum MTU (Maximum Transfer Unit) size for efficient wireless video communications over a packet switched access network is derived. The second part of the thesis investigates quality enhancement techniques for multimedia traffic transmitted over wireless channels. Quality enhancement is achieved at three levels of the transmission process: link level, application level and system level. Link level quality enhancement techniques are designed to optimise the allocation of link level parameter values according to the media characteristics. A novel Unequal Error Protection scheme and a novel Unequal Power Allocation scheme are designed to exploit the inherent diversity in the subjective importance of different sections of compressed media. The algorithms are developed and analysed for transmission of video over 3G wireless systems. The effectiveness of these algorithms is demonstrated through the results of simulated transmission over a UMTS channel. Application level quality enhancement techniques are designed to explore the time-varying nature of the wireless channel. A number of link adaptation schemes are proposed for real time video communication and real-time video streaming over 3G wireless systems. These algorithms are designed to enhance the perceptual video quality, and the system utilisation. This is achieved by adapting the allocated radio network parameters and the source parameters, according to a feedback channel condition. Simulation results show a significant performance improvement compared to non-adaptive schemes. Finally, system level adaptation techniques are designed for efficient radio resource allocation in multi-user scenarios. Two adaptive resource allocation schemes are proposed and analysed for real-time video communications in a UMTS system. The proposed algorithms are shown to provide improved performances in terms of average received video quality and user satisfaction. Key words: Wireless Communication, Multimedia communication. Video Transmission.
2
Muhovic, Admir. "Secure Wireless Communication". Thesis, KTH, Kommunikationssystem, CoS, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92023.
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The need for and requests for utilization of wireless equipment are growing rapidly. Advantages of using wireless communication are easy to realize. Having access to electronically stored information no matter where you are is a big advantage. Furthermore, wireless communication is increasingly utilized in everyday work and there is a constant development of new wireless equipment. Today, utilization of wireless communication is very practical as well as effective. On the other hand, using wireless equipment and communication entails risk unless efforts are made to secure this communication. Some wireless protocols exist and are used, despite their being vulnerable to attacks. Additionally, the traffic can easily be eavesdropped. Incorrect installation of wireless equipment contributes to the vulnerabilities of wireless communication. Some of the IT-equipment available on the market today offers wireless communication. This equipment is increasingly used within FMV. Such equipment includes: laptops, PDAs, cellular phones, etc. This wireless equipment, according to FMV’s information security policy, must be approved from a security viewpoint before it can be used at FMV. Thus an analysis of risks associated with usage of wireless equipment must take place and the mechanisms necessary to ensure adequate security must be identified. The document “Requirements on Security Functions (Kraven på SäkerhetsFunktioner, KSF)” identifies the technical and/or administrative requirements for such equipment.</p> The aim of this thesis was to analyze if it is possible to utilize wireless equipment at FMV, specifically, if it can be connected to the internal LAN at FMV. In other words, the wireless equipment must be able to offer security protection corresponding to the information security class: HEMLIG/RESTRICTED. The thesis contains an analysis of which security functions are available on the market today and evaluates whether these security functions meet the requirements given in KSF. The result is a proposal for the best security mechanism(s) within the constraints of KSF and the available equipment. The thesis proposes a technical solution along with suitable security mechanisms. The advantages and drawbacks of each has been analyzed. Additionally, the thesis presents a number of (administrative) security policies in order to be able to handle security aspects which are not covered by the KSF.Behoven och efterfrågan av mobil och trådlös utrustning är i dagsläget allt större. Fördelarna med att använda sig av trådlös kommunikation är enkla att inse. Att kunna ha tillgång till elektroniskt lagrad information oavsett var man än befinner sig är en stor fördel. Vidare implementeras trådlös kommunikation allt mer i det vardagliga arbetet samtidigt som utrustning för denna sorts kommunikation är i ständig utveckling. I slutändan är användandet av trådlös kommunikation väldigt praktiskt samtidigt som det är effektivt. Användandet av trådlös utrustning och kommunikation medför ett risktagande då denna typ av kommunikation allmänt är osäker. Detta eftersom teknologin fortfarande är i utvecklingsfasen. De i dagsläget aktuella trådlösa protokollen är sårbara för attacker och det är dessutom enkelt att avlyssna trafiken. Felaktig installation av utrustning bidrar dessutom också till att den trådlösa kommunikationen blir sårbar. En del av den IT-utrustning som idag finns tillgänglig ute på marknaden och som alltmer används inom FMV har möjlighet att kommunicera trådlöst med omgivningen. Exempel på sådan utrustning är bärbara datorer, PDA:er, mobiltelefoner mm. Denna typ av utrustning, dvs. trådlös utrustning, skall enligt FMVs informationssäkerhetspolicy godkännas från säkerhetssynpunkt innan den får tas i bruk på FMV. Det innebär att man utför en analys av vilka risker som är förknippade med användandet av trådlös utrustning samt att man identifierar adekvata skyddsåtgärder. Till sin hjälp använder man sig av Kraven på SäkerhetsFunktioner (KSF) som består av tekniska och/eller administrativa krav. Syftet med detta examensarbete var att undersöka om det finns möjlighet att använda trådlös utrustning på FMV, dvs. att denna används på interna LAN på FMV. Med andra ord skall den trådlösa utrustningen kunna erbjuda ett skydd motsvarande högst informationssäkerhetsklassen HEMLIG/RESTRICTED (H/R). Examensarbetet innefattar en analys av vilka säkerhetsfunktioner idag finns tillgängliga ute på marknaden och utvärderar huruvida dessa säkerhetsfunktioner uppfyller kraven givna i Kraven på SäkerhetsFunktioner (KSF). Resultatet är ett förslag på de bästa säkerhetsmekanismerna inom restriktionerna av KSF och den tillgängliga utrustningen. Examensarbetet föreslår en teknisk lösning med lämpliga säkerhetsmekanismer. Dess för- och nackdelar har analyserats. Examensarbetet presenterar dessutom ett antal (administrativa) säkerhets policies som hanterar säkerhetsaspekter som inte omhändertas av KSF.
3
Cottingham, David Naveen. "Vehicular wireless communication". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611258.
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Dagne, Carl, Johan Bengtsson i Ingemar Lindgren. "Microwave Wireless Communication System". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-232.
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The purpose of the project was to develop the hardware to a microwave wireless system working
at the frequency 2.45 GHz. The functionality of the system should also be easy to understand
since the system is to be used in an educational purpose. Much time has been spent impedance
matching components, a task that proved to be harder than we expected. Other work that has been
is layout of all parts, filter construction and the writing of an easy to understand thesis. After the
parts had been completed, they were tested in a network analyzer and/or spectrum analyzer.
Successful full system test has been done up to 400 meters, the length the system is to be used
for.
5
Herbert, Steven John. "Wireless communication in vehicles". Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/280675.
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There is an increasing interest in the deployment of wireless communication systems in vehicles. The motivation for this work is to provide a fundamental characterisation of the in-vehicle Electromagnetic (EM) wave propagation environment, and to demonstrate how this can be used to aid the deployment of wireless communication systems in vehicles. The fundamental characterisation of the in-vehicle EM wave propagation environment presented in this dissertation yields a number of useful outcomes. The instantaneous impulse response of the in-vehicle channel is characterised, which is presented in the form of a statistical model for arriving rays. Noticing that it is impractical to undertake a full statistical characterisation of the time-varying impulse response, the time variation of the in-vehicle channel is instead characterised as a Doppler spread. This approach provides parameters which are sufficient to perform an information theoretic analysis to lower bound the capacity of the in-vehicle channel. For typical operating conditions, it is found that the channel capacity is approximately equal to that of the same channel with perfect channel state information available at the receiver. Having established the fundamental EM wave propagation characteristics for a single in-vehicle wireless channel, the EM properties of the cavity itself are characterised. This is achieved through a thorough investigation into the analogy between vehicle cavities and reverberation chambers, specifically considering the quality factor (and hence time constant), EM isolation, and electric field uniformity of typical vehicle cavities. This approach yields the important insight that the root mean square delay spread is approximately the same for all wireless links in a typical vehicle cavity. Also, that the angular spread of energy received at any given location (away from the cavity boundaries) is approximately uniform, and that over short distances the coherence distance is well defined, and hence Multiple Input Multiple Output antenna arrays should work well in vehicles. To what extent a typical wireless system can exploit this characterisation depends on how well the parameters can be estimated by a typical wireless communication system. This is also addressed, specifically investigating the estimation of the cavity time constant, and channel time variation. It is found that both of these can be estimated well using a typical wireless sensor network system.
6
Jiang, Junyi. "Optical wireless communication systems". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/387239/.
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In recent years, Optical Wireless (OW) communication techniques have attracted substantial attention as a benefit of their abundant spectral resources in the optical domain, which is a potential solution for satisfying the ever-increasing demand for increased wireless capacity in the conventional Radio Frequency (RF) band. Motivated by the emerging techniques and applications of OW communication, the Institute of Electrical and Electronics Engineers (IEEE) had released the IEEE standard 802.15.7 for short-range optical wireless communications, which categorised the Physical layer (PHY) of the OW communication into three candidate-solutions according to their advantages in different applications and environments: 1) Physical-layer I (PHY I): Free Space Optical (FSO)communication employs high-intensity Light Emitting Diodes (LEDs) or Laser Diodes (LDs) as its transmitter. 2) Physical-layer II (PHY II) uses cost-effective, low-power directional white LEDs for the dual function of illumination and communication. 3) Physical III (PHY-III) relies on the so-called Colour-Shift Keying (CSK) modulation scheme for supporting high-rate communication. Our investigations can be classified into three major categories, namely Optical Orthogonal Frequency Division Multiplexing (OFDM) based Multiple-Input Multiple-Output (MIMO) techniques for FSO communications in the context of PHY I, video streaming in PHY-II and the analysis and design of CSK for PHY-III. To be more explicit, in Chapter 2 we first construct a novel ACO-OFDM based MIMO system and investigate its performance under various FSO turbulence channel conditions. However, MIMO systems require multiple optical chains, hence their power consumption and hardware costs become substantial. Hence, we introduced the concept of Aperture Selection (ApS) to mitigate these problems with the aid of a simple yet efficient ApS algorithm for assisting our ACO-OFDM based MIMO system. Since the channel conditions of indoor Visible Light Communication (VLC) environments are more benign than the FSO-channels of Chapter 2, directional white LEDs are used to create an “attocell” in Chapter 3. More specifically, we investigate video streaming in a multi-Mobile Terminals (MTs) indoor VLC system relying on Unity Frequency Reuse (UFR) as well as on Higher Frequency Reuse Factor based Transmission (HFRFT) and on Vectored Transmission (VT) schemes. We minimise the distortion of video streaming, while satisfying the rate constraints as well as optical constraints of all the MTs. In Chapter 4 we analyse the performance of CSK relying both on joint Maximum Likelihood (ML) Hard-Detection (HD), as well as on the the Maximum A posteriori (MAP) criterion-based Soft-Detection (SD) of CSK. Finally, we conceive both two- stage and three-stage concatenated iterative receivers capable of achieving a substantial iteration gain, leading to a vanishingly low BER.
7
Du, Hao. "Optical wireless MIMO communication". Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/70945/.
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This thesis provides an in-depth investigation and evaluation of infrared optical wireless MIMO communication systems to be applied in both indoor and outdoor environment. The principle objective of the research is to demonstrate both the advantages and disadvantages of the optical wireless MIMO systems using different modulation types. The first part provided analyses of important OW configurations using APD receivers using WMC model and SISO, MISO, SIMO and MIMO configuration. Thus, an analytical expression for 2-1 MISO, 1-2 SIMO and MIMO was successfully developed. This part also illustrates the coding gains possible using diversity schemes for APD OW systems. In the presence of strong fading, the SISO approach is rendered virtually useless, whereas diversity offers acceptable BER values. The results underpin the approach of this thesis, where indoor PIN diode based experimental measurements confirm the gains offered by diversity. In the second part of the work, several optical wireless MIMO systems applicable for the indoor environment are developed for three different modulation types, OOK modulation, PPM modulation and SIR-RZI modulation. These modulations are used in optical MIMO systems are studied for which, mathematical models that evaluate the BER performance of the MIMO system for different axis displacement and for different distances between transmitters and receivers. Based on the results, the PPM system has been shown to present the best BER performance, including high interference-resistance capability. A group of new mathematical models have been evaluated, which demonstrates a high level of correlation with the results derived from empirical models at 93%. Thus, the mathematical models developed and used for the specified evaluation appear to correspond reasonably well, and can be applied in future research on these aspects.
8
Кovalenko, Viktoriya, i Oksana Tykhenko. "Wireless communication safety analysis". Thesis, Proceedings the Seventh World Congress «Aviation in the XXI-st Century», September 19 – 21, 2016. – P. 5.4.46 – 5.4.48, 2016. http://er.nau.edu.ua/handle/NAU/29355.
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Gao, Zihao. "Wireless Powered Communication Networks". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17169.
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The limited life time of batteries is a crucial issue in energy-constrained wireless communications. Recently, the radio frequency (RF) wireless energy transfer (WET) technique has been developed as a new practical method to extend the life time of wireless communication networks. Inspired by this, wireless-powered communication network (WPCN) has attracted much attention. Therefore, in this thesis, we consider practical WET and wireless-powered information transmission in WPCNs. First we investigate a WPCN with two nodes, in which an access point (AP) exchanges information with a wireless-powered user. The user is assumed to have no embedded energy supply and needs to harvest energy from RF signals broadcast by the AP. Differing from existing work that focuses on the design of wireless-powered communication with one-way information flow, we deal with a more general scenario where both the AP and the user have information to transmit. Considering that the AP and user can work in either half-duplex or full-duplex mode as well as having two practical receiver architectures at the user side, we propose five elementary communication protocols for the considered system. Moreover, we define the concept of a throughput region to characterize the tradeoff between the uplink and downlink throughput in all proposed protocols. Numerical simulations are finally performed to compare the throughput regions of the proposed five elementary protocols. To further the study on WPCN, we investigate a wireless-powered two-way relay system, in which two wireless-powered sources exchange information through a multi-antenna relay. Both sources are assumed to have no embedded energy supply and thus first need to harvest energy from the radio frequency signals broadcast by the relay before exchanging their information via the relay. We aim to maximize the sum throughput of both sources by jointly optimizing the time switching duration, the energy beamforming vector and the precoding matrix at the relay. The formulated problem is non-convex and hard to solve in its original form. Motivated by this, we simplify the problem by reducing the number of variables and by decomposing the precoding matrix into a transmit vector and a receive vector. We then propose a bisection search, a 1-D search and an iterative algorithm to optimize each variable. Numerical results show that our proposed scheme can achieve higher throughput than the conventional scheme without optimization on the beamforming vector and precoding matrix at the relay. Due to the high attenuation of RF energy over a long distance, RF based wireless-powered communication is usually designed for low-power scenarios, e.g., wireless-powered sensor networks. Recently, magnetic induction (MI) based WET has been proposed to wirelessly transfer a large amount of energy. Inspired by this, we investigate MI based WET in WPCN. Specifically, we study a MI based wireless-powered relaying network, in which a MI source transmits information to a MI destination, with the help of a MI based wireless powered relay. We propose four active relaying schemes, which consider different relaying modes and different energy harvesting receiver architectures at the relay. We then aim to maximize the end-to-end throughput of each scheme by using a bisection search, a water-filling algorithm, a Lagrange multiplier, quasi-convex programming and an iterative algorithm. We compare the proposed active relaying schemes with passive relaying. Numerical results show that the proposed relaying schemes with a decode-and-forward relaying mode significantly improve the throughput over passive relaying.
10
Yamashita, Shota. "Coexistence of Wireless Communication and Non-communication Systems". Kyoto University, 2018. http://hdl.handle.net/2433/232420.
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Krause, Wolfram O. "Wireless communication networks : structure and dynamics of wireless multi-hop ad hoc communication networks /". Lichtenberg (Odenw.) : Harland media, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015507583&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Schuster, Ulrich G. "Wireless communication over wideband channels /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17565.
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Lee, Kah Ping. "Turbo equalization in wireless communication". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5844.
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Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 11, 2006) Includes bibliographical references.
14
Pakravan, Mohammad Reza. "Indoor infrared wireless communication channels". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/NQ57061.pdf.
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Ray, Adam A. Roppel Thaddeus A. "Cooperative robotics using wireless communication". Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/RAY_ADAM_44.pdf.
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Lu, Yang. "UWB antennas for wireless communication". Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569654.
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Ultra-wideband (UWB) technology is a promising solution to provide high data-rate transmission of the future wireless communication systems. The rapid development of UWB wireless communication systems has brought both challenges and: opportunities to novel UWB antenna designs. This thesis is concentrated on the analysis, design and measurement of compact antennas for UWB devices, which can be divided into three areas. / The first area investigated is small planar broadband antennas for wearable and positioning applications where the antennas with unidirectional radiation patterns may be preferred, since the energy will be focused on the desired direction. Furthermore, the interference from the environment behind the antenna can also be greatly minimised. Two low-profile broad band antennas with unidirectional radiation patterns are presented in this work. Their performance in terms of impedance bandwidth and radiation patterns is studied. Results show that they have a very broadband (>50% fractal bandwidth) and constant broadside unidirectional radiation patterns. Hence, they are good candidates and suitable for the in-body and radar applications The second research area is about the planar UWB monopole antennas. The radiation behaviour of the planar UWB monopole antenna is first investigated. It is found that an ultra-wide bandwidth of this type of antenna is achieved by both well-matched travelling wave modes and smooth transients between different higher order modes. However, there exists a common problem for the current planar UWB monopole antennas that their performance is heavily affected by the size of the ground plane. It is found that dimensional changes will influence the characteristic modes excited on the ground plane which directly affects the impedance and radiation of the antenna. A technique of cutting slots on the ground plane is then proposed to resolve the ground plane effect problem. The presence of the slots will introduce slot modes. Optimal slots can produce a strong coupling between the slot mode and the ground plane modes. This coupling makes the characteristic modes of planar UWB monopole insensitive to the size change of the ground plane, hence it effectively minimises the ground plane dependence of the antenna. Two different UWB monopole antennas are investigated using this technique. Both the simulated and measured results demonstrate that this method can indeed minimise the ground plane effects on the impedance matching and have very little effect on the other antenna parameters, such as radiation pattern, gain and I time domain performance. Additionally, a parametric study on the major geometric parameters related to the slots is performed to achieve an optimised design. The third area of my study is the measurement of UWB antenna radiation efficiency. Antenna radiation efficiency is one of the most important parameters when evaluating its performance. In the past, many different antenna efficiency measurement methods were proposed. However, how to measure the UWB antenna efficiency effectively is still a challenging issue. A novel source-stirred chamber/cap (SSC) method is proposed and developed to overcome the limitations of the existing methods. Different types of UWB antennas are employed as examples to demonstrate the usefulness of this new method. Promising results are obtained which prove the SSC method is very effective in measuring the UWB antenna efficiency. It is evident that this method has the potential to become a general antenna efficiency measurement approach.
17
Liu, Luyan. "Wireless Communication in Smart Housing". Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-37631.
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With the development of computer and information technology, information and network will be the inevitable trend of smart home which aims to offer a comfortable, efficient, and convenient home. In this thesis, the background, developments and limitations of smart home systems will be described. Wired and wireless technologies applied on the smart home network will be analyzed and a comparison of them will be made. Finally, the ZigBee technology is selected to design the wireless communication network. For the system design, the thesis describes an idea where cluster topology is chosen to design the smart home system and demonstrates the process of networking as well. Based on the Labview platform, a smart home system will be simulated to achieve the functions included in data acquisition, analysis, display and storage. More specially, I will focus on temperature monitoring and control of heating and cooling systems. Finally, an analysis of the advantages and disadvantages of the smart home system is given.
18
Bourget, Marc A. (Marc Anthony) 1979. "Expanding the wireless communication paradigm". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87185.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002."June 2002."
Includes bibliographical references (leaves 44-45).
by Marc A. Bourget.
M.Eng.
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Music, Craig 1978. "Expanding the wireless communication paradigm". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8077.
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Ding, Yuan. "Directional modulation secured wireless communication". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676283.
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The main objective of this work was the development of the directional modulation (DM) technique, which is a promising keyless physical layer security means for securing wireless communication in free space. It is realized, from a summary of the state-of-the-art OM systems, that although the OM concept appears to be a competitive candidate to enhance the secrecy performance of the next generation of wireless communication, it suffers various fundamental problems, which makes the OM research carried out in an unsystematic and inefficient manner. In order to integrate the previous scattered OM efforts and further pave the path for its applications, in this thesis a theoretical OM framework has been established and some key concepts and OM architectures have been validated via well designed experiments.
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Schuster, Ulrich G. "Wireless communication over wideband channels". Konstanz Hartung-Gorre, 2008. http://d-nb.info/993286984/04.
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Alhartomi, Mohammed. "Collaborative optical wireless communication systems". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/13153/.
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Toni, Laura <1982>. "Adaptive wireless multimedia communication systems". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/2117/1/Laura_Toni_tesi.pdf.
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In recent years, due to the rapid convergence of multimedia services, Internet and wireless communications, there has been a growing trend of heterogeneity (in terms of channel bandwidths, mobility levels of terminals, end-user quality-of-service (QoS) requirements) for emerging integrated wired/wireless networks. Moreover, in nowadays systems, a multitude of users coexists within the same network, each of them with his own QoS requirement and bandwidth availability. In this framework, embedded source coding allowing partial decoding at various resolution is an appealing technique for multimedia transmissions. This dissertation includes my PhD research, mainly devoted to the study of embedded multimedia bitstreams in heterogenous networks, developed at the University of Bologna, advised by Prof. O. Andrisano and Prof. A. Conti, and at the University of California, San Diego (UCSD), where I spent
eighteen months as a visiting scholar, advised by Prof. L. B. Milstein and Prof. P. C. Cosman. In order to improve the multimedia transmission quality over wireless channels, joint source and channel coding optimization is investigated in a 2D time-frequency resource block for an
OFDM system. We show that knowing the order of diversity in time and/or frequency domain can assist image (video) coding in selecting optimal channel code rates (source and channel code rates). Then, adaptive modulation techniques, aimed at maximizing the spectral efficiency, are investigated as another possible solution for improving multimedia transmissions. For both slow and fast adaptive modulations, the effects of imperfect channel estimation errors are evaluated, showing that the fast technique, optimal in ideal systems, might be outperformed by the slow adaptive modulation, when a real test case is considered. Finally, the effects of co-channel interference and approximated bit error probability (BEP) are evaluated in adaptive modulation techniques, providing new decision regions concepts, and showing how the widely used BEP
approximations lead to a substantial loss in the overall performance.
24
Toni, Laura <1982>. "Adaptive wireless multimedia communication systems". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/2117/.
Pełny tekst źródłaStreszczenie:
In recent years, due to the rapid convergence of multimedia services, Internet and wireless communications, there has been a growing trend of heterogeneity (in terms of channel bandwidths, mobility levels of terminals, end-user quality-of-service (QoS) requirements) for emerging integrated wired/wireless networks. Moreover, in nowadays systems, a multitude of users coexists within the same network, each of them with his own QoS requirement and bandwidth availability. In this framework, embedded source coding allowing partial decoding at various resolution is an appealing technique for multimedia transmissions. This dissertation includes my PhD research, mainly devoted to the study of embedded multimedia bitstreams in heterogenous networks, developed at the University of Bologna, advised by Prof. O. Andrisano and Prof. A. Conti, and at the University of California, San Diego (UCSD), where I spent
eighteen months as a visiting scholar, advised by Prof. L. B. Milstein and Prof. P. C. Cosman. In order to improve the multimedia transmission quality over wireless channels, joint source and channel coding optimization is investigated in a 2D time-frequency resource block for an
OFDM system. We show that knowing the order of diversity in time and/or frequency domain can assist image (video) coding in selecting optimal channel code rates (source and channel code rates). Then, adaptive modulation techniques, aimed at maximizing the spectral efficiency, are investigated as another possible solution for improving multimedia transmissions. For both slow and fast adaptive modulations, the effects of imperfect channel estimation errors are evaluated, showing that the fast technique, optimal in ideal systems, might be outperformed by the slow adaptive modulation, when a real test case is considered. Finally, the effects of co-channel interference and approximated bit error probability (BEP) are evaluated in adaptive modulation techniques, providing new decision regions concepts, and showing how the widely used BEP
approximations lead to a substantial loss in the overall performance.
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Cavallari, Riccardo <1986>. "Human-Centric Wireless Communication Networks". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7444/1/tesi.pdf.
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This thesis covers two main topics: the design and performance
evaluation of Wireless Body Area Networks (WBANs), and the simulation
and mathematical modeling of Delay Tolerant Networks (DTNs).
Different Medium Access Control (MAC) protocols for WBANs are
implemented on dedicated hardware in order to evaluate, through
extensive measurement campaigns, the performance of the network in
terms of packet loss rate, delay and energy consumption. Novel
solutions to cope with body shadowing and to improve the coexistence
with other wireless technologies, are presented and evaluated. An
analytic model for the CSMA/CA protocol defined in the IEEE 802.15.6
standard is also presented.
The benefits of offloading part of the traffic carried by a wireless
backbone to a DTN composed of mobile nodes in a urban environment, is
also investigated. A more analytic approach, mainly using tools from
stochastic geometry and Markov chains theory, is used to develop a
mathematical framework for the evaluation of the performance of
routing rules for DTNs.
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Cavallari, Riccardo <1986>. "Human-Centric Wireless Communication Networks". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7444/.
Pełny tekst źródłaStreszczenie:
This thesis covers two main topics: the design and performance
evaluation of Wireless Body Area Networks (WBANs), and the simulation
and mathematical modeling of Delay Tolerant Networks (DTNs).
Different Medium Access Control (MAC) protocols for WBANs are
implemented on dedicated hardware in order to evaluate, through
extensive measurement campaigns, the performance of the network in
terms of packet loss rate, delay and energy consumption. Novel
solutions to cope with body shadowing and to improve the coexistence
with other wireless technologies, are presented and evaluated. An
analytic model for the CSMA/CA protocol defined in the IEEE 802.15.6
standard is also presented.
The benefits of offloading part of the traffic carried by a wireless
backbone to a DTN composed of mobile nodes in a urban environment, is
also investigated. A more analytic approach, mainly using tools from
stochastic geometry and Markov chains theory, is used to develop a
mathematical framework for the evaluation of the performance of
routing rules for DTNs.
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ZHANG, LINCHAO. "Reliable Communication in Wireless Networks". Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2537290.
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Wireless communication systems are increasingly being used in industries and infrastructures since they offer significant advantages such as cost effectiveness and scalability with respect to wired communication system. However, the broadcast feature and the unreliable links in the wireless communication system may cause more communication collisions and redundant transmissions. Consequently, guaranteeing reliable and efficient transmission in wireless communication systems has become a big challenging issue. In particular, analysis and evaluation of reliable transmission protocols in wireless sensor networks (WSNs) and radio frequency identification system (RFID) are strongly required.
This thesis proposes to model, analyze and evaluate self-configuration algorithms in wireless communication systems. The objective is to propose innovative solutions for communication protocols in WSNs and RFID systems, aiming at optimizing the performance of the algorithms in terms of throughput, reliability and power consumption. The first activity focuses on communication protocols in WSNs, which have been investigated, evaluated and optimized, in order to ensure fast and reliable data transmission between sensor nodes. The second research topic addresses the interference problem in RFID systems. The target is to evaluate and develop precise models for accurately describing the interference among readers. Based on these models, new solutions for reducing collision in RFID systems have been investigated.
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Barros, João. "Reachback communication in wireless sensor networks". [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973065753.
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Acharya, Om Nath, i Sabin Upadhyaya. "Space Time Coding For Wireless Communication". Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19424.
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As the demand of high data rate is increasing, a lot of research is being conducted in the field of wireless communication. A well-known channel coding technique called Space-Time Coding has been implemented in the wireless Communication systems using multiple antennas to ensure the high speed communication as well as reliability by exploiting limited spectrum and maintaining the power. In this thesis, Space-Time Coding is discussed along with other related topics with special focus on Alamouti Space-Time Block Code. The Alamouti Codes show good performance in terms of bit error rate over Rayleigh fading channel. The performance of Altamonte’s code and MIMO capacity is evaluated by using MATLAB simulation.
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Nordberg, Jörgen. "Signal enhancement in wireless communication systems /". Ronneby : Department of Telecommunications and Signal Processing, Blekinge Institute of Technology, 2002. http://www.bth.se/fou.
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Ren, Kui. "Communication security in wireless sensor networks". Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-040607-174308/.
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Yu, Qiang. "Frequency synchronization techniques in wireless communication". Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54596/.
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In this thesis various iterative channel estimation and data detection techniques for time-varying frequency selective channels with multiple frequency offsets are proposed. Firstly, a maximum likelihood approach for the estimation of complex multipath gains (MGs) and real Doppler shifts (DSs) for a single input "single output (SISO) frequency selective channel is proposed. In a time di vision multiple access (TDMA) system, for example the third-generation global system, or mobile GSM communications, the pilot symbols are generally inadequate to provide enough resolution to estimate frequency offsets. Therefore, our approach is to use the pilot sequence for the estimation and equalization of the channel without consideration to frequency offsets, and then to use the soft estimates of the transmitted signal as a long pilot sequence to determine iteratively the multiple frequency offsets and refine the channel estimates. Inter-symbol interference (ISI) is removed with a linear structure turbo equalizer where the filter coefficients are chosen based on the minimum mean square error (MMSE) criterion. The detection performance is verified using the bit error rate (BER) curves and the frequency offset estimation performance through comparison with appropriate Cramer-Rao lower bounds. This work is then extended for a multi-user transmission system where the channel is modelled as a multi input multi output (MIMO) TDMA system. For the iterative channel estimation, the MIMO frequency selective channel is decoupled into multiple SISO flat fading sub-channels through appropriately cancelling both inter-symbol-interference (ISI) and inter-user-interference (IUI) from the received signal. The refined channel estimates and the corresponding frequency offset estimates are then obtained for each resolved MIMO multipath tap. Simulation results confirm a superior BER and estimation performance. Finally, these iterative equalization and estimation techniques are ex tended to orthogonal frequency division multiplexing (OFDM) based SISO and MIMO systems. For OFDM, the equalization is performed in two stages. In the first stage, the channel and the frequency offsets are estimated in the time domain, while in the second stage, the transmitted symbols are estimated in the frequency domain and the mean values and the variances of the symbols are determined in the frequency domain. These two procedures interact in an iterative manner, exchanging information between the time and frequency domains. Simulation studies show that the proposed iterative scheme has the ability to track frequency off sets and provide a superior BER performance as compared to a scheme that does not track frequency offsets.
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Yuen, Hector. "An ad-hoc wireless communication system". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37398.
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Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2006.Includes bibliographical references (p. 77-79).
This thesis studies the challenges of providing load balancing and fault-tolerant external links between ad-hoc multicast mesh networks. The work is the gateway component of a research platform called FluidVoice, a wireless audio communication system. This system consists of nodes forming a broadcast mesh based on 802.11. Some of these nodes called Stargates have the capability to communicate to the external world. The problem is that these gateways can fail or lose capacity unexpectedly. In this work we explore the ways to provide communications to the external world under unexpected gateway node failures, and variance of load. We propose and evaluate a distributed algorithm designed to form this robust and balanced interconnection. The algorithm is designed with robustness in mind, and takes into account failures in the outbound links as well as between the gateways, and it is focused to support real-time applications running over it. In this thesis we show that by adopting this algorithm, we can provide a reliable connection to the end-user even as gateways presence or capacity varies. The prototype version has about 20ms of additional transmission time in average, with an overhead of about 5% to 35% depending on the packet size, and a recovery time of 1 to 3 seconds. The redundant traffic generated in intermediate steps of the optimization problem can grow up proportionally to the number of participating gateway nodes, and reduces quickly to only the required amount of traffic.
by Hector Yuen.
S.M.
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Min, Rex K. (Rex Kee) 1976. "Energy and quality scalable wireless communication". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28272.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 165-171).
Nodes for emerging, high-density wireless networks will face the dual challenges of continuous, multi-year operation under diverse and challenging operating conditions. The wireless communication subsystem, a substantial consumer of energy, must therefore be designed with unprecedented energy efficiency. To meet this challenge, inefficiencies once overlooked must be addressed, and the system must be designed for energy scalability, the use of graceful energy vs. quality trade-offs in response to continuous variations in operational conditions. Using a comprehensive model framework that unifies cross-disciplinary models for energy consumption and communication performance, this work explores multi-dimensional trade-offs of energy and quality for wireless communication at all levels of the system hierarchy. The circuit-level "knob" of dynamic voltage scaling is implemented on a commercial microprocessor and integrated into a power aware, prototype microsensor node. Power aware abstractions encourage collaboration between the hardware, which fundamentally dissipates the energy, and software, which controls how the hardware behaves. Accurate models of hardware energy consumption reveal inefficiencies of routing techniques such as multihop, and the models are fused with information-theoretic limits on code performance to bound the energy scalability of the hardware platform. An application-specific protocol for microsensor networks is evaluated with a new, interactive Java simulation tool created expressly for energy-conscious, high density wireless networks. Close collaboration between software and hardware layers, and across the research disciplines that compose wireless communication itself, are crucial enablers for energy-efficient wireless communication.
by Rex Kee Min.
Ph.D.
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Johnson, Brent, Colin Madrid, Kevin Yiin, Hanwen Wang, Chengxi Li i Xizhi Tan. "3D Printed Antennas for Wireless Communication". International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596460.
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ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVThis paper describes the details of design and critical analysis of the process of 3D printing antennas for wireless communications applications. The subjective testing methods utilized were chosen specifically based on project scope and researcher capability. Our results indicate that more work is necessary in this field but that the basic idea is feasible.
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Lacerda, Neto Raul Liberato de. "Exploiting the wireless channel for communication". Nice, 2008. http://www.theses.fr/2008NICE4049.
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The recent development in digital communications has made wireless networks one of the most promising areas of research. Fueled by the advances in digital processing, high data rate connections have recently become the focus of research in the communication domain. The growth of the Internet and the introduction of a multitude of applications culminated in a new era of communications in which wireless networks play a very important role. However, the wireless environment still offers some challenges that need to be addressed before meeting next generation mobile requirements. Due to imperfect channel characterization and modeling, much of the potential of the wireless environment is wasted. Furthermore, the need of multiple simultaneous connections lead to the use of multiple access schemes that were not designed to cope with some of the wideband/multiple antenna wireless characteristics. The objective of the thesis is to treat these two points. The first part of this thesis is dedicated to the use of bayesian probability theory tools that enable the derivation of models based only on partial knowledge of the environment. Using Jaynes' maximum entropy principle, we present a framework that allows us to infer on the channel characteristics by choosing probability distributions that maximize entropy under the constraints that represent the actual state of knowledge. This technique is at the heart of scientific inference and has applications in many other fields. Probabilistic channel Models for two different types of environment are derived: wideband channels and multiple-input multiple-output (MIMO) channels. In the second part, the multiple access problem for ultra wideband (UWB) systems is considered. Despite the large amount of work conducted during recent years on UWB technology, no scheme can cope with the high dispersion of UWB channels and still offer reasonable spectral efficiency. An innovative scheme that exploits the users' channels to guarantee multiple access is introduced, entitled channel division multiple access (ChDMA)Le récent développement des communications mobiles a fait des réseaux sans fil un des secteurs technologiques les plus prometteurs. Stimulé par les avancées en traitement de l'information, le haut débit est récemment devenu le centre de la recherche dans le domaine des communications. La croissance des flux Internet et l'introduction d'une multitude d'applications ont abouti à une nouvelle ère des communications dans lesquelles les réseaux sans fil jouent un rôle très important. Cependant, l'environnement sans fil offre toujours quelques défis qui doivent être adressés avant d'atteindre les pré-requis nécessaires pour les futurs réseaux sans fils. En raison de la caractérisation imprécise du canal de transmission, une grande partie du potentiel du canal sans fil est gaspillé. En outre, les schémas de communications multi-utilisateurs actuels n'exploitent pas convenablement les différents degrés de liberté (espace et bande) du canal. Le but de cette thèse est de traiter précisément ces deux points. La première partie de cette thèse est consacrée à l'utilisation des outils de théorie des probabilités bayésiens qui permettent de générer des modèles basés seulement sur la connaissance partielle de l'environnement. A partir du principe de maximisation d'entropie, nous présentons une approche qui permet d'inférer sur les caractéristiques des canaux en choisissant les distributions de probabilité qui maximisent l'entropie sous des contraintes qui représentent l'état de la connaissance de l'environnement. Cette technique est à la base des procédés d'inférences et a connu un large succès dans différentes disciplines. Des modèles pour deux différents types d'environnement sont analysés et proposés: canaux à large bande et canaux multi-antennes (MIMO). Dans la deuxième partie, le problème d'accès multiple pour les systèmes ultra large bande (UWB) est étudié. Malgré la grande quantité de travaux effectués ces dernières années sur la technologie d'UWB, aucune technique d'accès multiple n'exploite actuellement la dispersion élevée des canaux d'UWB, ce qui engendre une faible efficacité spectrale. Un schéma innovant qui exploite les canaux des utilisateurs s'intitulant "Channel Division Multiple Access" (ChDMA) est proposé. Ce schéma fournit une solution très simple tout en obtenant une efficacité spectrale élevée
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Sepasian, Mojtaba. "Multibiometric security in wireless communication systems". Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/5081.
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This thesis has aimed to explore an application of Multibiometrics to secured wireless communications. The medium of study for this purpose included Wi-Fi, 3G, and WiMAX, over which simulations and experimental studies were carried out to assess the performance. In specific, restriction of access to authorized users only is provided by a technique referred to hereafter as multibiometric cryptosystem. In brief, the system is built upon a complete challenge/response methodology in order to obtain a high level of security on the basis of user identification by fingerprint and further confirmation by verification of the user through text-dependent speaker recognition. First is the enrolment phase by which the database of watermarked fingerprints with memorable texts along with the voice features, based on the same texts, is created by sending them to the server through wireless channel. Later is the verification stage at which claimed users, ones who claim are genuine, are verified against the database, and it consists of five steps. Initially faced by the identification level, one is asked to first present one’s fingerprint and a memorable word, former is watermarked into latter, in order for system to authenticate the fingerprint and verify the validity of it by retrieving the challenge for accepted user. The following three steps then involve speaker recognition including the user responding to the challenge by text-dependent voice, server authenticating the response, and finally server accepting/rejecting the user. In order to implement fingerprint watermarking, i.e. incorporating the memorable word as a watermark message into the fingerprint image, an algorithm of five steps has been developed. The first three novel steps having to do with the fingerprint image enhancement (CLAHE with 'Clip Limit', standard deviation analysis and sliding neighborhood) have been followed with further two steps for embedding, and extracting the watermark into the enhanced fingerprint image utilising Discrete Wavelet Transform (DWT). In the speaker recognition stage, the limitations of this technique in wireless communication have been addressed by sending voice feature (cepstral coefficients) instead of raw sample. This scheme is to reap the advantages of reducing the transmission time and dependency of the data on communication channel, together with no loss of packet. Finally, the obtained results have verified the claims.
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Fan, Ho Yin. "MIMO detection schemes for wireless communication /". View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20FAN.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 64-66). Also available in electronic version. Access restricted to campus users.
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Kennedy, B. Scott. "Reconfigurable multi-node wireless communication testbed". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004832.
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Li, Ziyi. "Wireless-Powered Communication with Energy Accumulation". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16123.
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In this thesis, I focus on the system design and performance analysis of wireless communication networks with radio frequency (RF) energy harvesting. Battery re-placement/recharging has always been a challenging issue in wireless communication networks, especially in large-scale networks like wireless sensor networks (WSNs). Recently, RF energy harvesting (EH) technology has been developed as a new viable solution to extend the lifetime of wireless networks via enabling wireless devices to harvest energy from RF signals. Inspired by this technique, wireless-powered communication networks (WPCNs) have attracted an upsurge of research interest. According to the protocols proposed in current literature, an EH user will exhaust all the energy it harvests straightway during this transmission block. This may be a sub-optimal solution, since this little amount of energy may not be able to contribute to an effective transmission. Therefore, in this thesis, I consider energy accumulation at each EH node by providing an energy storage (e.g. a rechargeable battery), so that it can an accumulate sufficient amount of harvested energy before transmission and wait to transmit in an appropriate time slot. To begin with, I first investigate wireless energy harvesting (WEH) technique in cooperative communication networks where the source and relay can both communicate with the destination. I refer to this kind of network as wireless-powered cooperative communication networks (WPCCNs). This WEH technique offers a new cooperation manner for wireless devices since the relay node is now able to harvest energy from the source’s information. In this thesis, I consider the relay as a wireless-powered node that has no external power supply; but it is equipped with an EH unit and a rechargeable battery so that it can harvest and accumulate energy from RF signals broadcast by the source. By fully incorporating the EH feature of the relay, an opportunistic relaying protocol was developed, termed accumulate-then-forward (ATF), for the considered WPCCN with a direct link. The discrete Markov chain is adopted to model the dynamic charging and discharging behaviors of the relay battery. Based on this, I derive a closed-form expression for the exact system outage probability of the proposed ATF protocol. Numerical results show that the ATF scheme can outperform the direct transmission one, especially when the amount of energy consumed by the relay for information forwarding is optimized. In order to further take advantage of the direct link between the source and destination, an incremental accumulate-then-forward (IATF) scheme was proposed to the considered WPCCNs. In the IATF protocol, the source sends its information to the destination via the direct link and requests the relay to cooperate only when it is necessary, such that the relay has more chances to accumulate energy. By modelling the charging/discharging behaviors of the relay battery as a finite-state Markov chain, I derive a closed-form expression for the system outage probability of the proposed IATF. Numerical results validate my theoretical analysis and show that the IATF scheme can significantly outperform the direct transmission scheme without cooperation and the ATF scheme. A comparison of these two schemes is also given to show examples of their advantages and disadvantages. One of the key features of WEH technique is one-to-many, where multiple EH nodes can harvest energy simultaneously from one single RF signal. The energy from broadcasted RF signals can thus be transferred to several EH nodes rather than only one EH node, which can increase the energy transfer efficiency of the whole communication network. Contrast to the single EH node previously, in the last chapter of this thesis, I investigate a WPCN with multiple EH nodes and focus on the multi-user scheduling problem. I assume a power beacon (PB) is deployed in WPCN dedicating to charge the EH nodes by broadcasting RF energy signals. With this PB-assisted WEH technique, the considered WPCN consists of a PB, an access point (AP) and multiple EH users attempting to transmit information toward the AP. In this thesis, I consider that only one EH user can be selected to forward its information, and the rest of the nodes will continue to harvest energy. In order to harvest energy effectively and transmit information efficiently, I proposed several types of multi-user scheduling schemes based on the availability of the channel state information (CSI), i.e. multi-user scheduling scheme without CSI, multi-user scheduling scheme using channel state information at the receiver (CSIR), and multi-user scheduling scheme using channel state information at the transmitter (CSIT). Two more Proportional Fairness scheduling schemes are proposed in order to achieve the fairness among all the EH users. Simulation results show that the availability of CSI can significantly improve the access outage probability, where the average probability of the user successfully connect to the AP is shown. Moreover, the fairness among different users can be dramatically improved by two Proportional Fairness schemes.
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Morshed, M. (Munim). "Wireless backhaul in future cellular communication". Master's thesis, University of Oulu, 2018. http://jultika.oulu.fi/Record/nbnfioulu-201809292841.
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Abstract. In 5G technology, huge number of connected devices are needed to be considered where the expected throughput is also very ambitious. Capacity is needed and thus used frequencies are expected to get higher (above 6 GHz even up to 80 GHz), the Cell size getting smaller and number of cells arising significantly. Therefore, it is expected that wireless backhaul will be one option for Network operators to deliver capacity and coverage for high subscriber density areas with reduced cost. Wireless backhaul optimization, performance and scalability will be on the critical path on such cellular system. This master’s thesis work includes connecting a base station by using the wireless backhaul by introducing a VPN in the proposed network. We find the bottleneck and its solution. The network is using 3.5 GHz wireless link instead of LAN wire for backhaul link between the EnodeB and the core network (OpenEPC). LTE TDD band 42 acting as a Wireless Backhaul (Link between EnodeB and Band 42 CPE Router). The status and attachment procedure are observed from different nodes of the openEPC and from the VPN machine. Step by step we have established a tunnel between the CPE device and the VPN server using PPTP and L2TP with IPSec tunneling protocol. The progression towards the final implementation brings in step by step all difficulties and bottlenecks are documented in the study.
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Abbas, Waqas Bin. "Energy Efficient Communication in Wireless Networks". Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3424869.
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This thesis investigates energy efficient communication in wireless networks. The work considers energy efficiency from both a device and a network perspective.
Firstly, we investigate the energy efficiency (EE) of a receiver equipped with large antenna arrays. In a receiver architecture, operating either at millimeter wave (mmWave) or at microwave (massive multiple input multiple output (MIMO)), the use of a high resolution analog-to-digital converter (ADC) is traditionally considered as a main bottleneck to achieve an energy efficient design. To address this issue, in contrast to previous works, we compared
the performance of analog, hybrid and digital beamforming (ABF, HBF and DBF) based receiver architectures with low resolution ADCs, and show that when power consumption of all receiver components is taken into account DBF results in a better spectral, power and energy efficiency than ABF and HBF in most scenarios for both control plane and data plane communication. Results also show that based on the ADC power consumption model there is an optimal number of ADC bits that results in a maximum EE (defined as
capacity/total power consumption). To further reduce the power consumption of DBF, a novel variable resolution ADC architecture is proposed, which motivates the use of variable resolution ADCs instead of conventional fixed resolution ADCs. To address the issue of energy consumption related to the directional cell search associated with a large antenna array system, we propose to exploit the availability of context information to reduce the
search delay associated with ABF and propose a low power phase shifters network based receiver architecture which compares and selects the best beam in analog hardware and requires only a single RF chain. We also propose a higher sub-carrier bandwidth based control plane structure to reduce the energy consumption of the directional cell discovery process.
Secondly, we study energy efficient communication in a multi-hop flooding network. Particularly, we study and analyze how in a multi-hop network a hybrid automated repeat request (HARQ) scheme based on fountain codes can reduce the probability of failure at the destination. The analysis is performed for both unrestricted and restricted flooding scenarios, and
results verify that below a certain minimum link failure probability restricted flooding performs similar to unrestricted flooding but with fewer transmissions compared to unrestricted flooding. This reduction in number of transmissions is directly related to an improvement in energy efficiency of an overall network. Moreover, we also proposed two practical restricted flooding policies; 1) Predetermined restriction, which performs similar to restricted flooding, and 2) Adaptive restriction, which adapts its number of transmissions according to the link failure probability and performs similar to unrestricted flooding. Furthermore, we also study the performance of a network in the presence of helping nodes which can decode and generate
extra redundancy packets in the network. Results show that the inclusion of helping nodes can further reduce the number of transmissions compared to a case where only the source is transmitting.Questa tesi indaga la comunicazione ad alta efficienza energetica nelle reti wireless. Il lavoro considera l'efficienza energetica sia da un dispositivo ed un prospettiva di rete. In primo luogo, si indaga l'efficienza energetica (EE) di un ricevitore dotato di grandi schiere di antenne. In un'architettura ricevitore, operando sia a onde millimetriche (mmWave) oa microonde (massiccia Multiple Input Multiple Output (MIMO)), l'uso di una alta risoluzione convertitore analogico-digitale (ADC) è tradizionalmente considerata come un collo di bottiglia principale ottenere un design ad alta efficienza energetica. Per risolvere questo problema, a differenza di precedenti lavori, abbiamo confrontato le prestazioni dei analogiche, ibride e beamforming digitale (ABF, HBF e DBF) architetture ricevitore based con ADC a bassa risoluzione, e mostrano che, quando il consumo di energia di tutti i componenti del ricevitore si tiene risultati considerazione DBF in una migliore efficienza spettrale, potenza ed energia rispetto ABF e HBF nella maggior parte degli scenari sia per piano di controllo e comunicazione dei dati aereo. I risultati mostrano anche che sulla base del modello di consumo energetico ADC c'è un numero ottimale di bit ADC che si traduce in un EE massimo (definito come Capacità / potenza totale assorbita). Per ridurre ulteriormente il consumo di energia di DBF, una nuova architettura di risoluzione ADC variabile viene proposto, che motiva l'uso di ADC risoluzione variabili anziché le convenzionali ADC risoluzione fissa. Per affrontare il problema del consumo energetico legato alla ricerca di cellule direzionale associato ad un grande sistema di antenne, si propone di sfruttare la disponibilità di informazioni di contesto per ridurre la Ritardo di ricerca associato con ABF e proporre un'architettura di ricevitore rete basata variatori di fase a bassa potenza che si confronta e seleziona il miglior trave in hardware analogico e richiede solo una singola catena RF. Si propone inoltre una struttura piana controllo basata banda sottoportante superiore per ridurre il consumo energetico del processo di rilevamento cellule direzionale. In secondo luogo, si studia la comunicazione ad alta efficienza energetica in una rete inondazioni multi-hop. In particolare, studiamo e analizziamo come in una rete multi-hop di un sistema ibrido automatizzato richiesta di ripetizione (HARQ) sulla base di codici a fontana in grado di ridurre la probabilità di guasto a destinazione. L'analisi viene eseguita per entrambi gli scenari di allagamento senza restrizioni e ristrette, e risultati verificare che al di sotto di un certo errore di collegamento minima probabilità inondazioni limitato esegue simile a inondazioni senza restrizioni, ma con un minor numero di trasmissioni rispetto alle inondazioni senza restrizioni. Tale riduzione del numero di trasmissioni è direttamente correlata ad un miglioramento dell'efficienza energetica di una rete complessiva. Inoltre, abbiamo anche proposto due pratiche politiche inondazioni restrizioni; 1) restrizione predeterminato, che svolge simili a inondazioni ristretta, e 2) restrizione adattivo, che adatta il suo numero di trasmissioni in base alla probabilità di guasto collegamento ed esegue simile a inondazioni senza restrizioni. Inoltre, abbiamo anche studiare le prestazioni di una rete in presenza di nodi che possono aiutare decodificare e generare pacchetti di ridondanza supplementare della rete. I risultati mostrano che l'inserimento di nodi contribuendo può ridurre ulteriormente il numero di trasmissioni rispetto al caso in cui solo la sorgente sta trasmettendo.
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Wang, Shendi. "Efficient transmission design for machine type communications in future wireless communication systems". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23647.
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With a wide range of potential applications, the machine type communication (MTC) is gaining a tremendous interest among mobile network operators, system designers, MTC specialist companies, and research institutes. The idea of having electronic devices and systems automatically connected to each other without human intervention is one of the most significant objectives for future wireless communications. Low data rate transmission and the requirement for low energy consumption are two typical characteristics for MTC applications. In terms of supporting low cots MTC devices, industrial standards will be more efficient if designers can re-use many features of existing radio access technologies. This will yield a cost effective solution to support MTC in future communication systems. This thesis investigates efficient MTC waveform and receiver designs for superior signal transmission quality with low operational costs. In terms of the downlink receiver design, this thesis proposes a novel virtual carrier (VC) receiver system for MTC receivers, which aims to reduce the maximum bandwidth to improve the data processing efficiency and cost-efficiency by using analogue filters to extract only sub-carriers of interest. For the VC receiver systems, we thus reduce the sampling rate in order to reduce the number of subsequent processing operations, which significantly reduces the analogue-to-digital converter (ADC) cost and power consumption while providing high signal to interference noise ratio (SINR) and low bit to error rate (BER) to support low data rate MTC devices. Our theoretical equations account for the interference effect of aliasing on the sub-carrier location, and this helps the system designer to evaluate what kind of filters and receiver sampling rate can be used to balance the energy cost and detection performance. In terms of the uplink waveform design, considering the enhanced number of MTC devices in the future communication systems, i.e. the fifth generation (5G) communications, the same tight synchronisation as used in today appears not to be cost-effective or even possible. Synchronisation signals, which aim to provide a perfect time or frequency synchronisation in the current fourth generation (4G) communication systems (known as the long-term evolution, LTE), is much more costly for low data rate MTC transmissions. The system bandwidth will be significantly reduced if a base station tries to synchronise all received signals among hundreds or thousands MTC devices in one transmission time period. In terms of relaxing the synchronisation requirements, this thesis compares and analyses the side-lobe reduction performance for several candidate multi-carrier waveforms to avoid these problems. We also propose the infinite impulse response universal filtered multi-carrier (UFMC) system and the overlap and add UFMC system, which significantly reduce the processing complexity compared with the state of the art UFMC techniques. This thesis derives closed-form expressions for the interference caused by time offsets between adjacent unsynchronised MTC users. Our analytical equations can be used in both simple and complex time-offset transmission scenarios, and enable the system designer to evaluate the SINR, the theoretical Shannon capacity and the BER performance.
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Sohaib, Sarmad. "Energy efficient cooperative wireless communications". Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/energy-efficient-cooperative-wireless-communications(a852e1e2-04ad-4311-8004-53babe529e1b).html.
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Cooperative diversity exploits the broadcast nature of wireless channels and uses relays to improve link reliability. Most cooperative communication protocols are assumed to be synchronous in nature, which is not always possible in wireless communication. Also the relay nodes are assumed to be half duplex which in turn reduces the spectral efficiency. In this thesis, we first present a novel asynchronous cooperative communication protocol exploiting polarization diversity, which does not require synchronization at the relay node. Dual polarized antennas are employed at the relay node to achieve full duplex amplify-and-forward (ANF) communication. Hence the transmission duration is reduced which results into an increased throughput rate. Capacity analysis of the proposed scheme ascertains the high data rate as compared to conventional ANF. Bit error rate (BER) simulation also shows that the proposed scheme significantly outperforms both the non-cooperative single-input single-output and the conventional ANF schemes. Considering channel path loss, the proposed scheme consume less total transmission energy as compared to ANF and non-cooperative scheme in more practical distance range. Thus the proposed scheme is suitable for high rate and energy efficient relay-enabled communication. In addition to that, we also present a novel power allocation scheme for multiple relay nodes that results in efficient cooperative multiple-input multiple-output (MIMO) communication. Considering channel path loss, the total transmission energy is distributed between the source and the relay nodes. The energy distribution ratio between the relay and direct link is optimized such that the quality of received signal is maintained with minimum total transmission energy consumption. We calculate the energy distribution ratio analytically and verified it through computer simulation. With the new power allocation scheme, the system also obtains an increased channel capacity as compared to cooperative scheme with conventional equal power allocation and non-cooperative scheme. Optimal relay positioning with proposed energy allocation scheme is also explored to maximize the capacity.
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Sun, Zhi. "Reliable and efficient communication in wireless underground sensor networks". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41150.
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Wireless Underground Sensor Networks (WUSNs) are the networks of wireless sensors that operate below the ground surface. These sensors are either buried completely in soil medium, or placed within a bounded open underground space, such as underground mines and tunnels. WUSNs enable a wide variety of novel applications, including intelligent irrigation, underground structure monitoring, and border patrol and intruder detection.
This thesis is concerned with establishing reliable and efficient communications in the network of wireless sensor nodes that are deployed in either soil medium or underground mines and tunnels. In particular, to realize WUSNs in soil medium, two types of signal propagation techniques including Electromagnetic (EM) waves and Magnetic Induction (MI) are explored. For EM wave-based WUSNs, the heterogeneous network architecture and dynamic connectivity are investigated based on a comprehensive channel model in soil medium. Then a spatio-temporal correlation-based data collection schemes is developed to reduce the sensor density while keeping high monitoring accuracy. For MI-based WUSNs, the MI channel is first analytically characterized. Then based on the MI channel model, the MI waveguide technique is developed in order to enlarge the underground transmission range. Finally, the optimal deployment algorithms for MI waveguides in WUSNs are analyzed to construct the WUSNs with high reliability and low costs. To realize WUSNs in underground mines and tunnels, a mode-based analytical channel model is first proposed to accurately characterize the signal propagation in both empty and obstructed mines and tunnels. Then the Multiple-Input and Multiple-Output (MIMO) system and cooperative communication system are optimized to establish reliable and efficient communications in underground mines and tunnels.
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Xia, Bin, i 夏斌. "Enhanced techniques for broadband wireless communications". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29144231.
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Yin, Hujun. "Cross layer design and optimization of wireless networks /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5904.
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Zhang, Mingliu. "Wireless communication for sparse and rural areas". Diss., Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/zhang/ZhangM0807.pdf.
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Liu, Lingjia. "On delay-sensitive communication over wireless systems". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2725.
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Ali, Omar Ahmed. "Delay-sensitive communication over wireless multihop channels". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2715.
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