Since the frantic race towards the Shannon bound [1] commenced in the early 1950’s, linear block codes have become integral components of most digital communication systems. Both binary and non-binary linear block codes have proven themselves as formidable adversaries against the impediments presented by wireless communication channels. However, prior to the landmark 1974 paper [2] by Bahl et al. on the optimal Maximum a-Posteriori Probability (MAP) trellis decoding of linear block codes, practical linear block code decoding schemes were not only based on suboptimal hard decision algorithms, but also code-specific in most instances. In 1978 Wolf expedited the work of Bahl et al. by demonstrating the applicability of a block-wise Viterbi Algorithm (VA) to Bahl-Cocke-Jelinek-Raviv (BCJR) trellis structures as a generic optimal soft decision Maximum-Likelihood (ML) trellis decoding solution for linear block codes [3]. This study, largely motivated by code implementers’ ongoing search for generic linear block code decoding algorithms, builds on the foundations established by Bahl, Wolf and other contributing researchers by thoroughly evaluating the VA decoding of popular binary and non-binary linear block codes on realistic narrowband and wideband digital communication platforms in lifelike mobile environments. Ideally, generic linear block code decoding algorithms must not only be modest in terms of computational complexity, but they must also be channel aware. Such universal algorithms will undoubtedly be integrated into most channel coding subsystems that adapt to changing mobile channel conditions, such as the adaptive channel coding schemes of current Enhanced Data Rates for GSM Evolution (EDGE), 3rd Generation (3G) and Beyond 3G (B3G) systems, as well as future 4th Generation (4G) systems. In this study classic BCJR linear block code trellis construction is annotated and applied to contemporary binary and non-binary linear block codes. Since BCJR trellis structures are inherently sizable and intricate, rudimentary trellis complexity calculation and reduction algorithms are also presented and demonstrated. The block-wise VA for BCJR trellis structures, initially introduced by Wolf in [3], is revisited and improved to incorporate Channel State Information (CSI) during its ML decoding efforts. In order to accurately appraise the Bit-Error-Rate (BER) performances of VA decoded linear block codes in authentic wireless communication environments, Additive White Gaussian Noise (AWGN), flat fading and multi-user multipath fading simulation platforms were constructed. Included in this task was the development of baseband complex flat and multipath fading channel simulator models, capable of reproducing the physical attributes of realistic mobile fading channels. Furthermore, a complex Quadrature Phase Shift Keying (QPSK) system were employed as the narrowband communication link of choice for the AWGN and flat fading channel performance evaluation platforms. The versatile B3G multi-user multipath fading simulation platform, however, was constructed using a wideband RAKE receiver-based complex Direct Sequence Spread Spectrum Multiple Access (DS/SSMA) communication system that supports unfiltered and filtered Complex Spreading Sequences (CSS). This wideband platform is not only capable of analysing the influence of frequency selective fading on the BER performances of VA decoded linear block codes, but also the influence of the Multi-User Interference (MUI) created by other users active in the Code Division Multiple Access (CDMA) system. CSS families considered during this study include Zadoff-Chu (ZC) [4, 5], Quadriphase (QPH) [6], Double Sideband (DSB) Constant Envelope Linearly Interpolated Root-of- Unity (CE-LI-RU) filtered Generalised Chirp-like (GCL) [4, 7-9] and Analytical Bandlimited Complex (ABC) [7, 10] sequences. Numerous simulated BER performance curves, obtained using the AWGN, flat fading and multi-user multipath fading channel performance evaluation platforms, are presented in this study for various important binary and non-binary linear block code classes, all decoded using the VA. Binary linear block codes examined include Hamming and Bose-Chaudhuri-Hocquenghem (BCH) codes, whereas popular burst error correcting non-binary Reed-Solomon (RS) codes receive special attention. Furthermore, a simple cyclic binary linear block code is used to validate the viability of employing the reduced trellis structures produced by the proposed trellis complexity reduction algorithm. The simulated BER performance results shed light on the error correction capabilities of these VA decoded linear block codes when influenced by detrimental channel effects, including AWGN, Doppler spreading, diminished Line-of-Sight (LOS) signal strength, multipath propagation and MUI. It also investigates the impact of other pertinent communication system configuration alternatives, including channel interleaving, code puncturing, the quality of the CSI available during VA decoding, RAKE diversity combining approaches and CSS correlation characteristics. From these simulated results it can not only be gathered that the VA is an effective generic optimal soft input ML decoder for both binary and non-binary linear block codes, but also that the inclusion of CSI during VA metric calculations can fortify the BER performances of such codes beyond that attainable by classic ML decoding algorithms. / Dissertation (MEng(Electronic))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

Orientador: Jaime Portugheis / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-03T15:25:23Z (GMT). No. of bitstreams: 1 Cunha_DanielCarvalhoda_M.pdf: 3453050 bytes, checksum: 13fe48dc7912e447d190ba1ba03e67dd (MD5) Previous issue date: 2003 / Resumo: Neste trabalho desenvolvemos um estudo sobre a aplicação de um algoritmo de de-codificação iterativa (turbo) de códigos produto em sistemas de transmissão que utilizam dois tipos de canais não-gaussianos: o canal CDMA de salto rápido em freqüência e o canal com ruído impulsivo juntamente com modulação BPSK. Para ambos os casos, propusemos uma maneira de calcular a confiabilidade das decisões tomadas após cada iteração, que leva em conta as densidades de probabilidade dos canais considerados. No caso do canal CDMA, os resultados mostraram que, para códigos de taxas baixa, média e alta, o desempenho do sistema melhora com o aumento do número de iterações de decodificação, o que comprova a validade da proposta. No caso de canais com ruído impulsivo, além da validade da proposta, ve-rificamos que o conhecimento da relação sinal-ruído do canal pelo decodificador pode melhorar o desempenho do sistema. Entretanto, para alguns valores dos parâmetros do ruído impulsivo, verificamos que uma escolha antecipada dos fatores a e ? do algoritmo iterativo que garanta a convergência do mesmo, pode se tornar uma tarefa bastante árdua / Abstract: In this work we develop a study of iterative (turbo) algorithms for product codes applied to transmission systems which utilize two types of non-Gaussian channels: a fast frequency hopping CDMA channel and impulsive noise channels with BPSK modulation. In both cases, we propose a way to calculate the reliability of decisions made after each iteration taking into account the probability density functions of the considered channels. In the case of a CDMA channel, for low, medium and high rate codes, the results showed that the performance of the systems becomes better as the number of decoding iterations increases, a result that validates the proposal. In the case of impulsive noise channels, we verified not only the validity of the proposal but also that the decoder knowledge of channel signal-to-noise ratios can improve the performance of the system. However, for some specific values of impulsive noise parameters, we verified that to give a predefined value to a and ? factors for the iterative algorithm which guarantees its convergence, can become a considerable difficult task / Mestrado / Mestre em Engenharia Elétrica

The museum of the twenty-first century is operating against the backdrop of ongoing social concerns pertaining to climate change, gender inequalities and racial tensions, and often exhibitions become the contact zones where those expressions are formulated. This research analyses how a democratic and inclusive philosophical perspective such as the Tigens Metod (or method of the thing) is executed by museum professionals. In doing so, Stuart Hall’s model of encoding/decoding is applied as the theoretical framework in investigating the process of exhibition production. It is argued that occasionally resistant positions can emerge from the museum’s ideological discourse and that key actors within the museum field yield different codes according to their own framework of knowledge and relations of production. This challenges the basic assumption in Hall’s model that media institutions yield one singular preferred code into the system. Overall, it is argued that an object-oriented democracy has the potential of challenging power structures, albeit still contingent upon the choices made by museum professionals.

Error-corecting codes are used during most of data transmissions these days. To save space, we would like to use codes which are able to correct enough errors without extending the message too much. The expander codes look promising - they are asymptotically optimal, however, in practice they are just too long. Better expander constructions could be achieved via randomness con- ductors. In this thesis, we explain what conductors are and which constructions are possible for them. In the end we will convert them to expanders and almost get expander codes which are short enough for practical use but nevertheless good. 1

This thesis deals with processing of video content on Android platform. Libraries for video encoding and decoding usable on this platform are described first. One of these libraries - FFmpeg - is used as core to design and implement middleware video-processing library. This library will provide simple but e fective API for multimedia Java applications.

The thesis deals with reverse techniques in software engineering. It presents practical application of software reverse engineering, used tools and approaches. The topic of instruction decoding is discussed in detail. Two basic methods are presented-linear sweep and recursive descent. Their strengths and weaknesses are highlighted. Subsequently a decompiler developed by AVG Technologies is introduced. The decompiler is retargetable. This feature allows to decompile applications of multiple platforms into various target languages. The aim of  the thesis is to design and implement algorithm for  decoding binary files into high-level representation. The designed algorithm is based on modified recursive descent algorithm, which uses control flow information. In order to achieve more accurate decoding results, symbol table records and other additional information are used. The proposed algorithm was implemented for the AVG Technologies retargetable decompiler. The tests showed that the implemented algorithm improved the function detection in decoded programs. Furthermore, the implemented solution allows to decode files that could not be analysed using the previous version of the decompiler.

The purpose of this thesis is to find out how young adults perceive gambling companies' video commercials in Sweden. A fast rise of commercials from gambling companies have evolved in recent years. As of January 2021, 102 companies have been approved for a Swedish gambling license. The total number of people gambling has not increased, but the total turnover has increased rapidly. Online casinos are considered one of the most addictive forms of gambling and therefore researchers claim that commercials from online casinos have the largest effect on people compared to other gambling forms. This makes it interesting to investigate video commercials in relation to young adults who are considered to be the biggest risk group to develop a gambling problem. To gain insight, we selected three video commercials and performed an in-depth analysis based on the method multimodal content analysis. Two focus group interviews were conducted with participants between the ages of 18-24 years. The focus groups were shown three commercials from three different gambling companies and were then asked about their opinion and interpretation of the commercials. The results were further analysed by the study’s theoretical framework of Stuart Hall's (1973) communication model encoding/decoding was used to analyse the video commercials and the answers from the focus groups.  The data from the focus group interviews indicated that gambling commercials could potentially have an impact on influencing young adults ages 18-24 years. The respondent's interpretation was generally negative since the majority of the participants disliked the video commercials and thought that the commercials were disturbing. Among the fifteen participants, three of them responded positively to some of the commercials and got more interested in wanting to start playing at online casinos after viewing the three video commercials. This suggests that gambling video commercials could have a negative influence.

From its introduction to its quindecennial, network coding have built a strong reputation in enhancing packet recovery process and achieving maximum information flow in both wires and wireless networks. Traditional studies focused on optimizing the throughput of the network by proposing complex schemes that achieve optimal delay. With the shift toward distributed computing at mobile devices, throughput and complexity become both critical factors that affect the efficiency of a coding scheme. Instantly decodable network coding imposed itself as a new paradigm in network coding that trades off this two aspects. This paper presents a survey of instantly decodable network coding schemes that are proposed in the literature. The various schemes are identified, categorized and evaluated. Two categories can be distinguished namely the conventional centralized schemes and the distributed or cooperative schemes. For each scheme, the comparison is carried out in terms of reliability, performance, complexity and packet selection methodology. Although the performance is generally inversely proportional to the computation complexity, numerous successful schemes from both the performance and complexity viewpoint are identified.

The purpose of this study is to investigate how Max Burgers construct themselves as an environmentally friendly company through their video advertisements. Additionally the purpose is to investigate how young, loyal customers can perceive Max’s attempt to portray  themselves as an environmentally friendly company, in the fast food industry through their advertisements. The two research questions are as follows: 1)   How does Max construct their advertisements in the campaign “Climate Positive Burgers”? 2)   How do Max’s young, loyal customers perceive Max’s video advertisements in the campaign “Climate Positive Burgers”?   The chosen theoretical framework incorporated into the study are Stuart Hall’s theory of Encoding/Decoding and Kenneth Burke’s theory of identification.  Data has been collected through an online survey, individual online semi-strucuted interviews and multimodal analysis. The study found that the way Max constructs their video advertisements can vary. With one video being constructed around being relatable and embracing humor, while the other was constructed on seriousness and artistic elements. In addition to this, it was found that all three types of readings according to Hall’s theory were perceived by the loyal customers interviewed. However, oppositional and dominant readings were more frequent. Finally, it was concluded that idealistic identification is present in consumers, due to loyal customers sharing some of the same values that Max are communicating in the video advertisements.

Syfte och frågeställningar: Studiens syfte är att studera hur publiken tolkar budskap och förhåller sig till information från företagen McDonalds och Max hamburgare när de kommunicerar miljömässig hållbarhet. Studiens frågeställningar är följande: • Hur ser publikens attityder gentemot snabbmatskedjorna ut? • Hur värderar publiken informationen från Max hamburgare och McDonalds? • Hur påverkar företagens marknadsföring konsumenters köpvanor och val för att stödja miljön? Metod och material: De metoder som använts i studien är fokusgruppsintervjuer och innehållsanalyser. Det empiriska materialet är genererat från deltagarnas samtal under fokusgruppsintervjuerna. Huvudresultat: Resultatet av fokusgruppsintervjuerna visar att deltagarna hade en negativ inställning till McDonalds, i synnerhet när McDonalds kommunicerar sitt arbete för miljön. Däremot förknippar många av deltagarna Max hamburgare med ett stort engagemang för miljön. Den negativa respektive positiva inställning speglade hur de förhöll sig till reklamfilmerna. Slutsatsen som studien kommit fram till är att publikens attityder och förutfattade meningar har stor betydelse för hur ett budskap från företagen tas emot av publiken, och trots att företagen kommunicerar miljömässig hållbarhet så är det inget som påverkar konsumentens köpbeslut. Köpbeslutet baseras på smak och vad personen i fråga är sugen på.