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Riaz, Bilal. "EXIT chart analysis for compressive turbo codes". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66782.
Pełny tekst źródłaLes turbo codes ont atteint des performances près de la limite de Shannon dans la communication de données sur des canaux bruités. Les diagrammes EXIT (EXtrinsic Information Transfer) [15] récemment proposés sont devenus une partie essentielle de la conception de turbo codes et ont été utilisés en tant que substituts aux simulations traditionnelles du taux d'erreur binaire. Il a été démontré que les turbo codes compressés atteignent des performances près de l'entropie dans différents problèmes de codage de source [1], [46], [74]. L'objectif principal de cette thèse est d'étendre les diagrammes EXIT des turbo codes pour canaux aux turbo codes pour sources et également étendre cette technique aux décodeurs itératifs de taille fixé.Après une revue initiale de littérature et recherche pertinent, la technique de EXIT charts est augmenté à l'analyse de performance de codes turbo compressés. Au contraire de la dernière tentative d'une telle augmentation [24] et [32], l'augmentation dérivée dans cette thèse donne des résultats fiables qui correspondents à la performance simulée de codes turbo compréhensives. De plus, une borne inferieure est obtenue pour illustrer la connexion et les différences entre la technique de EXIT charts de cette thèse et de celle proposé dans [32]. Finalement, la technique de EXIT charts est augmenté à l'analyse de performance de décodeurs analogues itératifs et l'implémentation numérique de décodage turbo basée sur l'arithmétique de précision finie.Plusieurs résultats numériques ont été obtenus pour illustrer l'application réussie des dérivés de la technique du graphe EXIT. Premièrement, l'analyse de la performance du graphe EXIT dérivées est utilisée pour plusieurs seules sources de compression basée sur des encodeurs concaténés en parallèle et en série. En conséquence, la technique des graphes EXIT développée dans ce
Hsu, Teh-Hsuan. "Robust concatenated codes for the slow Rayleigh fading channel". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2723.
Pełny tekst źródłaKarjalainen, J. (Juha). "Broadband single carrier multi-antenna communications with frequency domain turbo equalization". Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514295027.
Pełny tekst źródłaTiivistelmä Tässä työssä tutkitaan edistyksellisten moniantennivastaanotto- ja lähetysmenetelmien käyttöä radioresurssien tehokkuuden parantamiseen laajakaistaisessa yhden kantoaallon kommunikaatiossa. Työssä keskitytään erityisesti laskennallisesti tehokkaiden taajuustasossa suoritettavien iteratiivisten kanavakorjaintekniikoiden kehittämiseen yhden ja usean käyttäjän multiple-input multiple-output (MIMO) -kommunikaatiossa taajuusselektiivisen radiokanavan yli. Toinen tutkimuksen painopiste on lähetystehon optimointi yhden käyttäjän MIMO-kommunikaatiossa, jossa iteratiivisen kanavakorjaimen konvergenssiominaisuudet otetaan huomioon. Työssä ehdotetaan uudenlaista iteratiivista taajuustasossa suoritettavaa soft-cancellation (SC) ja minimum mean square error (MMSE) -suodatukseen pohjautuvaa joint-over-antenna (JA) monen käyttäjän ilmaisumenetelmää nousevan siirtokanavan tiedonsiirtoon taajuusselektiivisessa radiokanavassa. Ehdotettu tajuustasossa suoritettava usean käyttäjän MIMO-lähetyksen ilmaisumenetelmä vaatii selvästi vähemmän laskentatehoa verrattuna aikatason menetelmään. Tämän lisäksi ehdotetulla menetelmällä voidaan saavuttaa merkittävää suorituskykyhyötyä verrattuna antenna-by-antenna (AA) -pohjaiseen iteratiiviseen vastaanottimeen kun lähetysantennien ja käyttäjien kokonaislukumäärä on suurempi kuin vastaanotinantennien. Suorituskykyhyöty pätee myös tilakorrelaation tapauksessa. Työssä tutkitaan lisäksi olemassa olevien lineaaristen esikoodaustekniikoiden, esim. maximum information rate (MaxRate) and minimum sum mean square error (MinSumMSE), vaikutusta taajuustasossa suoritettavaan iteratiivisen kanavakorjaimen konvergenssiominaisuuksiin xtrinsic information transfer (EXIT) -analyysin avulla. Työssä ehdotetaan uudenlaista EXIT-analyysi-pohjaista lähetystehon minimointimenetelmää yhden kantoaallon MIMO-lähetykseen käyttäen iteratiivista taajuustason SC-MMSE-kanavakorjainta. Menetelmä ottaa huomioon iteratiivisen kanavakorjaimen konvergenssiominaisuudet. Ehdotettu convergence constrained power allocation (CCPA) -menetelmä erottaa tilatason häiriön lähetteiden välillä hyödyntäen singular value decomposition (SVD) -tekniikkaa ja minimoi lähetystehon ja saavuttaa samalla keskinäisinformaatiotavoitteet jokaiselle lähetteelle iteraatioiden jälkeen vastaanottimessa. Lähetystehon minimointiongelma voidaan muotoilla konveksiksi optimointiongelmaksi. Kahden keskinäisinformaatiorajoitteen erityistapaukselle johdetaan Lagrangen duaalifunktio ja ratkaistaan sen duaalifunktio. Työssä kehitetään lisäksi kaksi CCPA-pohjaista heuristista menetelmää. Numeeriset tulokset osoittavat ehdotettujen CCPA-pohjaisten menetelmien suoriutuvan paremmin verrattuna olemassa oleviin menetelmiin
Shepherd, David Peter, i RSISE [sic]. "Optimisation of Iterative Multi-user Receivers using Analytical Tools". The Australian National University. Research School of Information Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20081114.221408.
Pełny tekst źródłaBenaddi, Tarik. "Sparse graph-based coding schemes for continuous phase modulations". Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/16037/1/Benaddi_Tarik.pdf.
Pełny tekst źródłaYlioinas, J. (Jari). "Iterative detection, decoding, and channel estimation in MIMO-OFDM". Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514262203.
Pełny tekst źródłaTervo, V. (Valtteri). "Joint multiuser power allocation and iterative multi-antenna receiver design". Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207292.
Pełny tekst źródłaTiivistelmä Väitöskirjassa tutkitaan lähettimessä tapahtuvan tehoallokoinnin sekä vastaanottimessa tapahtuvan signaalin suodatuksen yhteisoptimointia monikäyttöön suunnatussa langattomassa moniantennikommunikaatiossa. Langattomien laitteiden lukumäärän kasvaessa energiatehokkuuden merkitys tiedonsiirtolinkkien suunnittelussa korostuu. Soluihin perustuvassa langattomassa tietoliikenteessä keskimääräisen tehonkulutuksen pienentäminen ylälinkkilähetyksessä (käyttäjältä tukiasemaan) on tärkeää käyttäjän kannalta, sillä se pidentää laitteen akun kestoa. Lähettimen tehovahvistimen (high power amplifier (HPA)) tehonkulutus on kuitenkin verrannollinen lähetyksen huipputehoon. Väitöskirjassa luodaaan uusia menetelmiä sekä vertaillaan tehoallokointia yhden kantoaallon taajuustason monikäyttöön (single carrier frequency division multiple access (SC-FDMA)) ja ortogonaalisen taajuustason monikäyttöön (orthogonal FDMA (OFDMA)) perustuvissa lähetysteknologioissa. Työn ensimmäisessä osiossa tavoitteena on keskimääräisen tehonkulutuksen pienentäminen monen käyttäjän ylälinkkikommunikaatiossa suunnittelemalla tehoallokointimenetelmä, joka ottaa huomioon iteratiivisen vastaanottimen konvergenssiominaisuudet. Työssä ehdotettu menetelmä takaa vastaanotetun informaation halutun laadun (quality of service (QoS)) riittävän monen vastaanottimessa tehdyn iteraation jälkeen. Huipputehon ja keskitehon suhteen (peak to average power ratio (PAPR)) pienentäminen missä tahansa lähetyksessä on hyödyllistä, sillä sen ansiosta voidaan käyttää energiatehokkaampia ja halvempia tehovahvistimia. Työn jälkimmäisessä osiossa tavoitteena on kontrolloida lähetetyn signaalin huipputehon ja keskitehon suhdetta. Työn ensimmäisessä osiossa esitetyn QoS-rajoitteen lisäksi tehoallokointia rajoitetaan symbolisekvenssikohtaisella PAPR-rajoitteella SCFDMA- ja OFDMA-lähetyksessä. Lisäksi esitetään tilastollinen menetelmä, jossa rajoitetaan lähetetyn signaalin tehon varianssia. Kun käytetään yhtäaikaisesti QoS- ja PAPR-rajoitteita, voidaan tiedonsiirtokanavaan suunnitella optimaalinen tehoallokointi ottaen huomioon tehovahvistimen epälineaarisuudet. Työssä esitetty PAPR-rajoite on kuitenkin geneerinen, ja se voidaan sovittaa mihin tahansa SCFDMA- tai OFDMA- optimointikehykseen. Työssä esitettävien optimointiongelmien tavoitteena on käyttäjien summatehon minimointi. Suurin osa työssä esiintyvistä ongelmista on ei-konvekseja, joten siinä esitetään kaksi vaihtoehtoista peräkkäinen konveksi approksimaatio (successive convex approximation (SCA)) -menetelmää kaikille ei-konvekseille rajoitteille. Numeeriset tulokset osoittavat, että esitetyt tehoallokointimenetelmät pienentävät merkittävästi keskimääräistä tehonkulutusta mahdollistaen lisäksi adaptiivisen PAPR-kontrolloinnin. Väitöskirjassa esitettyjen menetelmien avulla voidaan pidentää mobiilikäyttäjien akun kestoa sekä erityisesti parantaa solun reunakäyttäjien palvelun laatua
Gilra, Deepak. "A class of non-binary LDPC codes". Texas A&M University, 2003. http://hdl.handle.net/1969/67.
Pełny tekst źródłaHuusko, J. (Jarkko). "Communication performance prediction and link adaptation based on a statistical radio channel model". Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211473.
Pełny tekst źródłaTiivistelmä Työn tavoitteena on kehittää luotettava semianalyyttinen suorituskyvyn ennustusmenetelmä tehokkaalle iteratiiviselle vastaanottimelle, joka käsittelee taajuusselektiivisen, vastaanotinpäässä tilakorreloituneen moniantennikanavan kautta kulkeneita tilakanavoituja signaaleja. Toisessa vaiheessa esitettyjä ennustusmenetelmiä hyödynnetään mukauttamalla lähetystehoa tai modulaatioastetta ja koodisuhdetta (adaptive modulation and coding [AMC]), samalla säilyttäen tavoitteeksi asetetun kehysvirhesuhteen (frame error rate [FER]). Suorituskyvyn ennustusmenetelmä hyödyntää kanavan tilastollisia ominaisuuksia – kohinan varianssia, eroteltavien etenemispolkujen lukumäärää sekä vastaanottimen korrelaatiomatriisin ominaisarvoja – ennustaakseen signaali–kohina-plus-interferenssisuhteen (signal-to-interference-plus-noise ratio [SINR]) jakauman taajuustasossa toimivan, häiriötä poistavan pienimmän keskineliösumman kanavakorjaimen lähdössä. SINR-jakaumasta johdetaan pehmän symboleista biteiksi -muunnoksen jälkeisten logaritmisten bittitodennäköisyyksien suhdelukujen (log-likelihood ratio [LLR]) jakauma. Keskinäisinformaation siirroskartat perustuvat LLR:ien varianssin sekä keskinäisinformaation väliseen bijektiivisyyteen. Informaatio on kanavakoodattu 3rd Generation Partnership Project -standardin mukaisella turbokoodilla. Turbodekooderin toiminta on kanavasta riippumatonta, joten dekooderin lisäinformaation siirroskartat (extrinsic information transfer [EXIT] charts) voidaan simuloida itsenäisesti. Hyödyntämällä kanavakorjaimen lähdön pehmeiden bittipäätösten LLR:ien varianssin jakaumaa, on mahdollista arvioida millä todennäköisyydellä korjaimen satunnaisen kanavarealisaation siirroskartta leikkaa dekooderin siirroskartan. Tämä todennäköisyys voidaan tulkita kehysvirhesuhteeksi. Koska suorituskyvyn ennustusmenetelmä ei vaadi hetkellistä tietoa kanavan tilasta, sitä voidaan hyödyntää lähetyksen mukautuksessa. Mukautuvassa tehonsäädössä modulaatio ja koodisuhde eivät muutu. Lähetin pyrkii iteratiivisella tehonsäädöllä löytämään korjaimen lähdölle LLR-jakauman, joka tuottaa halutun kehysvirhesuhteen. Mukautuvassa modulaation ja koodisuhteen valinnassa lähetysteho säilyy vakiona. Modulaatioaste vaikuttaa korjaimen lähdön LLR-jakaumaan ja koodisuhde dekooderin siirroskartan muotoon. Iteratiivisesti koodisuhdetta säätämällä lähetin pyrkii löytämään modulaation ja koodisuhteen yhdistelmän, joka saavuttaa tavoitellun kehysvirhesuhteen. Vertikaalisesti tilakanavoiduissa järjestelmissä mukautuvaa tehonsäätöä täydennetään lähetystehoa mukauttavilla uudellenlähetyksillä, kun taas mukautuvaa modulaation ja koodisuhteen valintaa täydennetään puolestaan koodisuhdetta pienentävillä automattisilla uudelleenlähetyspyynnöillä (hybrid automatic repeat request [HARQ])
Mothi, Venkatesan Sabaresan. "Exit charts based analysis and design of rateless codes for the erasure and Gaussian channels". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1924.
Pełny tekst źródłaCleyet-Marel, Julien. "Le développement du système politique tibétain en exil". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM1010.
Pełny tekst źródłaThis public law thesis deals with the development of the Tibetan political system in exile. The objective was to carry out a detailed research on roots texts and commentaries on law and other relevant documents passed in the Tibetan refugee community, in order to explain the functioning of the Central Tibetan Administration, which for all practical purposes functions as the Tibetan-government-in-exile, although not formally recognized as such by the world at large and in particular by the host government. This work covers the various institutions of political representation, decision-making and governance within the Tibetan Refugee Community. Considering all this elements, we reached at the conclusion that the basics fundamentals laid down by this Charter, and the substantive and procedural laws and other rules, are inevitable for the immediate and long-term functioning of the Tibetan government in exile
Chehade, Tarek. "Optimisation d'un précodeur MIMO-OFDM dans le contexte de l'estimation aveugle et semi-aveugle du canal de communication". Thesis, Brest, 2015. http://www.theses.fr/2015BRES0077/document.
Pełny tekst źródłaChannel estimation plays an important role in wireless mobile communications, especially in MIMO systems. Unlike conventional channel estimation techniques based on training sequences or pilot symbols, blind techniques does not require the insertion of training symbols and allow higher throughput. The main problems of the blind lies in the ambiguity over the estimated channel. Based on the same methods as the blind estimation, the semi-blind estimation techniques are more robust. They exploit the blind information along with information provided by a small number of training symbols. The channel estimation is useful in MIMO systems and allows the precoding of the MIMO-OFDM signal by applying a pre-mixture in order to improve performance. Many types of precoders exist and their performance varies depending not only on the optimization criteria (Water-Filling, MMSE, Equal Error, max-SNR, max-d min ...), but also on the estimated channel. In this thesis we study the impact of using the channel information (CSI) from the blind and semi-blind estimation techniques to apply MIMO linear precoders. We also present a statistical study of the estimation error of these methods. The optimization of these precoders leads eventually to use another process allowing more performance improvement: the error correcting codes. We are particularly interested in non-binary LDPC codes and their association with linear MIMO precoders. We show that a matching is possible, and is beneficial in some cases. The optimization of this combination has allowed us to propose a new robust and more efficient precoder based on the maximization of mutual information
Nhan, Nhat-Quang. "Optimisation de précodeurs linéaires pour les systèmes MIMO à récepteurs itératifs". Thesis, Brest, 2016. http://www.theses.fr/2016BRES0062/document.
Pełny tekst źródłaThe long-term evolution (LTE) and the LTE-Advanced (LTE-A) standardizations are predicted to play essential roles in the future fifth-generation (5G) mobile networks. These standardizations require high data rate and high quality of service, which assures low error-rate and low latency. Besides, as discussed in the recent surveys, low complexity communication systems are also essential in the next 5G mobile networks. To adapt to the modern trend of technology, in this PhD thesis, we investigate the multiple-input multiple-output (MIMO) wireless communication schemes. In the first part of this thesis, low-complex forward error correction (FEC) codes are used for low complexity and latency. By considering iterative receivers at the receiver side, we exploit MIMO linear precoding and mapping methods to optimize the error-rate performance of these systems. In the second part of this thesis, non-binary low density parity check (NB-LDPC) codes are investigated. We propose to use MIMO precoders to reduce the complexity for NB-LDPC encoded MIMO systems. A novel low complexity decoding algorithm for NB-LDPC codes is also proposed at the end of this thesis
Uhlemann, Elisabeth. "Adaptive Concatenated Coding for Wireless Real-Time Communications". Doctoral thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-369.
Pełny tekst źródłaDoktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, 2198, Technical report. D, 29,
CORRÊA, Fernanda Regina Smith Neves. "Mapeamento de bits para adaptação rápida a variações de canal de sistemas QAM codificados com LDPC". Universidade Federal do Pará, 2017. http://repositorio.ufpa.br/jspui/handle/2011/9457.
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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
Os codigos com matriz de vericação de paridade de baixa densidade (LDPC) tem sido adotados como estrategia de correção de erros em diversos padrões de sistemas de comunicação, como nos sistemas G.hn (padrão que unifica as redes domesticas) e IEEE 802.11n (padrão para redes sem o locais). Nestes sistemas com modulação de amplitude em quadratura (QAM) codicados com LDPC, mapear propriamente os bits codificados para os diferentes sub-canais, considerando o fato de os sub-canais terem diferentes qualidades, garante uma melhora no desempenho geral do sistema. Nesse sentido, esta Tese apresenta uma nova técnica de mapeamento de bits, baseada na suposição de que bits transmitidos em sub-canais \bons" ajudam bits transmitidos em sub-canais \ruins". Isto e possível através de algumas restrições impostas ao grafo de Tanner associado, semelhantes aos códigos Root-LDPC. A otimização deste mapeamento de bits utilizando curvas de transferência de informação extrínseca (EXIT charts) também e apresentada. Observa-se que esse mapeamento tem a vantagem de um espaço de busca de otimização reduzido quando aplicado ao sistema com modo de transmissão de portadora única. Além disso, em situações nas quais o espaço de busca não e tão reduzido, como em aplicações baseadas em multiplexação por divisão de frequência ortogonal (OFDM), chegou-se a uma simples regra pratica associada as restrições do mapeamento de bits que praticamente elimina a necessidade de uma otimização. Por fim, um estudo do impacto do nível de desequilíbrio de contabilidade através dos sub-canais sobre o desempenho do mapeamento de bits e apresentado. Os resultados das simulações mostram que a estratégia de mapeamento de bits melhora o desempenho do sistema, e que, na presença de variações do canal, o sistema pode, adaptativamente, aplicar um novo mapeamento de bits sem a necessidade de recorrer a uma otimização complexa, podendo ser muito útil em sistemas práticos.
Low-Density parity-check (LDPC) codes are being adopted as the error correction strategy in di erent system standards, such as the G.hn (home networking standard) and the IEEE 802.11n (wireless local standard). In these LDPC-coded quadrature amplitude modulation (QAM) systems, mapping the LDPC coded bits properly to the di erent sub-channels considering the fact that sub-channels have di erent qualities ensures an improved overall system performance. Accordingly, this thesis presents a new bit mapping technique based on the assumption that bits transmitted in \good" sub-channels, help bits transmitted in \bad" sub-channels. This can be made possible through some restrictions to be imposed on the associated Tanner graph, akin to Root-LDPC codes. An optimization of the root-like bit mapping through extrinsic information transfer (EXIT) charts analysis is also presented. We show that this mapping has the advantage of a reduced optimization search space when applied to single-carrier based systems. Moreover, in situations where the search space is not só reduced, such as in orthogonal frequency division multiplexing (OFDM)-based applications, we arrive at a rule of thumb associated with the bit mapping constraints that practically eliminates the need for an optimization. Finally, a study of the impact of the level of reliability imbalance across the sub-channels on the performance of the root-like bit mapping is presented. Simulation results show that the new bit mapping strategy improves performance, and that in the presence of channel variations, the system can, adaptively, apply a new bit mapping without the need of a complex optimization, which can be very useful in practical systems.
Wang, Chenxi. "EXIT chart analysis of coded multiple antenna systems /". 2005. http://wwwlib.umi.com/dissertations/fullcit/3189306.
Pełny tekst źródłaSu, Chia-Wei, i 蘇佳偉. "Research and analysis of EXIT chart for MIMO-OFDM system". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/76657729443945938285.
Pełny tekst źródła國立臺灣科技大學
電子工程系
98
In this thesis, we worked on the architecture of 4G wireless communication systems. Our research was focused on iterative detection and decoding algorithms in MIMO-OFDM systems. Since the popularity of wireless online and wireless communications is increasing, the number of users has also increased. For the finite wireless spectrum, we have to divide wireless spectrum effectively and maximize spectrum efficiency. Then we can generate multiple independent parallel channels and transmit data simultaneously by using the multi-input multi-output (MIMO). Therefore using MIMO improves spectrum efficiency without increasing bandwidth. We can obtain the physical layer for 4G wireless communications by combining MIMO with orthogonal frequency-division multiplexing (OFDM). Then we used IRA code on the MIMO-OFDM system, and analyzed the detector and decoder characteristics by using EXIT charts. Furthermore, we employed curve fitting techniques to approach channel capacity. In addition to we observed that the PDF of its extrinsic information does not approach a Gaussian distribution, and the mean-to-variance ratio of the PDF is not what we expected. The two events described above caused inaccuracies in the trajectory and characteristic curves. So, we propose a method to solve the problem and also modify the curve fitting technique to analyze the behavior of the detector and decoder accurately. Then we can know if the detector matches the decoder and make their trajectory curves to convergence.
Liu, Yi-Chang, i 劉益彰. "On the Design of the BICM-ID Systems with EXIT Chart". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/22440013649520426481.
Pełny tekst źródła國立交通大學
電信工程系所
94
In the bit-interleaved coded modulation systems with iterative decoding (BICM-ID), a good labeling (bit mapping) is one of the key factors that dictate the system performance. In this thesis, Extrinsic Information Transfer (EXIT) chart, a popular tool to analyze the convergence behavior of an iterative decoding system, is employed for the labeling design. By changing the slopes of the detector transfer curves and selecting the most suitable labeling for the outer code, we show that the system performance can be significantly improved. In addition, EXIT chart is employed to design good trellis-pruned and punctured convolutional codes in BICM-ID systems to provide different levels of performance and code rate trade off.
Su, Jing-Fang, i 蘇敬方. "The Implementation of Exit Chart with Log-MAP Algorithm in Turbo Decoding". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/05108357626229536157.
Pełny tekst źródła國立中正大學
通訊工程研究所
95
In nowadays, Turbo codes have already been widely applied to many wireless communication systems and yield a remarkable performance approaching Shannon Limit. The turbo encoder consists of two or more traditional convolutional encoders that are connected in parallel or in cascade and then sends out the codeword. Decoding of the received coded messages is based on BCJR algorithm published in 1974. Later on, a log-MAP algorithm derived from BCJR algorithm is published to simplify the decoding computation such that the decoding procedure becomes faster and easier for implementation. To analyze the convergence behavior of turbo decoding based on iterative log-MAP algorithm, mutual information transfer characteristics of soft in/soft out decoders are proposed as a tool to better understand the convergence behavior of iterative decoding schemes. The exchange of extrinsic information is visualized as a decoding trajectory in the extrinsic information transfer chart (EXIT chart). In this thesis, we will build up the aforementioned tools following the work by Stephan ten Brink. And then we will simulate the transfer characteristics and the decoding trajectories. We use it to verify that the behavior of decoding trajectories will be predicted appropriately by the transfer characteristics curve.
Lee, Yao-Nan, i 李曜男. "Design and Analysis of Wireless Systems with Factor Graph and EXIT Chart". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/00866603033792064443.
Pełny tekst źródła國立清華大學
通訊工程研究所
96
To satisfy the demand for ubiquitously accessing multimedia data services, researchers have been continuing to develop various techniques which aim at pushing the overall system throughput to its limit. From the literature, research challenges towards this end include the developments of 1) an efficient space-time encoding and modulation scheme to raise the transmission rate, 2) a practical iterative receiver to recover the corrupted transmit-signals, and 3) a brand-new network architecture with an efficient scheduling algorithm to exploit the possible reuse of spatial resources without mutual interference. Each of the three challenges is not an easy-to-deal-with obstacle, for example, designing an efficient scheduling algorithm involves a complex multi-dimensional optimization which in nature is an NP-complete problem. However, thanks to the recent celebrated break-through in the EXtrinsic Information Transfer (EXIT) chart and the Graph theory, this thesis presents the progress we have made toward solving the three challenges with the help of the EXIT chart and Graph techniques. First, a close-to-Shannon-limit space-time encoding and modulation scheme for multiple-input multiple-output (MIMO) system is developed with the help of the EXIT chart by researchers at Bell Lab in 2004, which maps the coded bits of an irregular low-density parity-check (LDPC) code directly onto a modulation signal set. Instead of further searching for more capacity-approaching LDPC codes for all the practical MIMO system configuration, we develop several universal-good LDPC codes by investigating the relationship between the LDPC codes and the underlying MIMO system configuration through the EXIT chart and the large-system performance analysis technique. We demonstrate that the ratio of the numbers of the transmit and the receive antennas plays a crucial role in such LDPC-Coded MIMO systems, and the rewards for redesigning LDPC codes are not so much when the antenna ratio is unchanged. Second, since the channel estimation techniques through Wiener filtering are believed to be efficient methods for receivers to recover the corrupted transmit-signals, it is especially desired to know whether the promising idea of iterative processing can be applied to the receivers consisting of soft-information-aided Wiener-filter-based channel estimators and error-correction decoders. Therefore, we wish to investigate 1) how different variants of the two functional blocks interact, and 2) whether such iterative interactions can improve or degrade the system performance through a unified EXIT chart analysis. It is shown that the iterative processing between Wiener-filter-based channel estimator and error-correction decoder does not always improve the receiver performance, depending on 1) which family the error-correction code is from, and 2) how we utilize the soft information of the coded bits at the Wiener-filter-based channel estimator. Third, the cellular relay network capable of multi-hop data transmission seems to be a promising network architecture to boost the overall system throughput. However, since simultaneous data transmissions are allowed in such network, it needs an efficient scheduling algorithm to avoid the frequent data collisions problem. Otherwise, significantly higher data packet throughput in a relay network can never be achieved. A novel distributed algorithm tackling with this NP-complete scheduling problem is developed through the recent modeling and computational methodology of factor graphs. Numerical experiments show that the proposed distributed scheduling algorithm not only obtains average packet throughput comparable or even better than some exhaustive-search-based algorithms, but also takes care of the throughput fairness issue among all the MSs.
Wang, Chu-Yan, i 王楚硯. "EXIT-Chart Based Labeling Design for Bit-interleaved Coded Modulation with Iterative Decoding". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/r3sgr6.
Pełny tekst źródła國立交通大學
電信工程系所
95
In this thesis, constellation labeling is jointly designed with the outer code by using an EXIT-chart based analysis to improve the performance of bit-interleaved coded modulation with iterative decoding (BICM-ID). A systematic design method is proposed to obtain a set of labelings with good EXIT-chart characteristics for the regular one-dimensional (complex) modulation. Given an outer code, the best matched labeling can be employed to improve the BER performance. Furthermore, the method is extended to the multi-dimensional modulation case, where a group of bits are mapped to a vector of one-dimensional complex symbols. This general mapping strategy allows for more flexibility and potential performance improvements. Verified by the simulation results, our design provides a significant SNR gain over the conventional ones.
Chen, Kuo-Sheng, i 陳國勝. "EXIT chart analysis of bit interleaving binary code in FFH/MFSK systems under multitone jamming". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/7zn55d.
Pełny tekst źródła國立臺北科技大學
電腦與通訊研究所
102
In this paper, we focus on FFH/MFSK communication systems. After adding multitone jamming and passing through the channel, we compare the performance in different error correcting codes. In our system, the channel we used are Additional White Gaussian Noise channel and Rayleigh selective fading channel. In the use of error correcting codes, we select using convolutional codes and turbo codes. And the decoder is iterative decoding. In order to compare with the performance of different encoder and decoder, so our performance analysis is use the method named Extrinsic Information Transfer (EXIT) chart. And in this paper, we simulate the performance of bit interleaving binary code. From the simulation result, the concatenated non-binary code is better than the without concatenated non-binary code. And the convolutional codes will have better performance than turbo codes.
Shepherd, David Peter. "Optimisation of Iterative Multi-user Receivers using Analytical Tools". Phd thesis, 2008. http://hdl.handle.net/1885/49357.
Pełny tekst źródłaZhang, Zeyang. "Coarsely quantized Massive MU-MIMO uplink with iterative decision feedback receiver". Thesis, 2020. http://hdl.handle.net/1828/11719.
Pełny tekst źródłaGraduate
Wan, Ping. "Channel estimation for OFDM in fast fading channels". Thesis, 2011. http://hdl.handle.net/1828/3413.
Pełny tekst źródłaGraduate
Brown, Raymond. "Design of low-density parity-check Codes for multiple-input multiple-output wireless systems". Thesis, 2009. http://hdl.handle.net/1959.13/41187.
Pełny tekst źródłaMobile telephony, wireless networks and wireless telemetry systems have gone from simple single-input single-output wireless architectures with low data transmission rates to complex systems employing multiple antennas and forward error correction algorithms capable of high data transmission rates over wireless channels. Claude Shannon provided the fundamental capacity limits for a communications system and it can be shown that the capacity for a single-input single-output systems is limited in it’s capability to provide for modern wireless applications. The introduction of multiple-input multiple-output systems employing multiple antenna elements and orthogonal coding structures proved beneficial and could provide the capacities required for modern wireless applications. This thesis begins with an introduction and overview of space-time coding and the codes of Tarokh, Jafarkhani and Alamouti. Further, this thesis provides an introduction and overview to the family of forward error correction codes known as low-density parity-check (LDPC) codes. LDPC codes, when employed over Gaussian channels, provide near-Shannon limit performance and the question is posed as to their suitability for a wireless multiple-input multiple-output system employing multiple antennas and space-time coding. This question is answered by the use and demonstration of LDPC codes as outer codes to a MIMO system employing space-time block codes and a modified maximum-likelihood decoder. By modifying the space-time block-code decoder to provide a soft-information output, iterative decoders such as the sum-product algorithm can be employed to provide significant performance gains over a Rayleigh flat-fading channel. Further the use of design tools such as EXIT charts can then be used to design codes. The key to allowing the use of EXIT charts is the observation that a MIMO system employing orthogonal transmissions in a Rayleigh flat-fading channel is the equivalent to a SISO channel employing Nakagami-m fading coefficients. The seemingly complex MIMO system can now be analyzed in the form of a simpler SISO equivalent allowing the use of techniques such as EXIT charts to be employed in order to design codes with known and predictable performance haracteristics. This thesis demonstrates this technique and shows by example the performance gains that can be achieved for MIMO systems and opens some further questions for future research.
Brown, Raymond. "Design of low-density parity-check Codes for multiple-input multiple-output wireless systems". 2009. http://hdl.handle.net/1959.13/41187.
Pełny tekst źródłaMobile telephony, wireless networks and wireless telemetry systems have gone from simple single-input single-output wireless architectures with low data transmission rates to complex systems employing multiple antennas and forward error correction algorithms capable of high data transmission rates over wireless channels. Claude Shannon provided the fundamental capacity limits for a communications system and it can be shown that the capacity for a single-input single-output systems is limited in it’s capability to provide for modern wireless applications. The introduction of multiple-input multiple-output systems employing multiple antenna elements and orthogonal coding structures proved beneficial and could provide the capacities required for modern wireless applications. This thesis begins with an introduction and overview of space-time coding and the codes of Tarokh, Jafarkhani and Alamouti. Further, this thesis provides an introduction and overview to the family of forward error correction codes known as low-density parity-check (LDPC) codes. LDPC codes, when employed over Gaussian channels, provide near-Shannon limit performance and the question is posed as to their suitability for a wireless multiple-input multiple-output system employing multiple antennas and space-time coding. This question is answered by the use and demonstration of LDPC codes as outer codes to a MIMO system employing space-time block codes and a modified maximum-likelihood decoder. By modifying the space-time block-code decoder to provide a soft-information output, iterative decoders such as the sum-product algorithm can be employed to provide significant performance gains over a Rayleigh flat-fading channel. Further the use of design tools such as EXIT charts can then be used to design codes. The key to allowing the use of EXIT charts is the observation that a MIMO system employing orthogonal transmissions in a Rayleigh flat-fading channel is the equivalent to a SISO channel employing Nakagami-m fading coefficients. The seemingly complex MIMO system can now be analyzed in the form of a simpler SISO equivalent allowing the use of techniques such as EXIT charts to be employed in order to design codes with known and predictable performance haracteristics. This thesis demonstrates this technique and shows by example the performance gains that can be achieved for MIMO systems and opens some further questions for future research.
Jeřábková, Kamila. "Česká folková scéna a politická persekuce po roce 1977". Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-370782.
Pełny tekst źródłaDeutschová, Kristýna. "Komparace pohledu exilového tisku na události v Československu na příkladu Národní politiky a Českého slova". Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-373021.
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