On Computing Shannon’s Sphere Packing Bound and Applications

file: :home/zaki/.local/share/data/Mendeley Ltd./Mendeley Desktop/Downloaded/Ahmed, Ambroze, Tomlinson - 2007 - On Computing Shannon’s Sphere Packing Bound and Applications.pdf:pdf keywords: SPB mendeley-tags: SPBA new method to numerically evalu- ate Shannon’s lower bound is presented in this pa- per. This new method is based on the Incomplete Beta function and permits the exact evaluation of the Sphere Packing Bound for a large range of code sizes, rates and probability of error. Comparisons with cur- rent standards (DVB–RCS, DVB–S2 and 3GPP) are also presented and discussed. It is shown that cur- rent standard coding schemes are about 0.6dB from the Shannon Limit corrected for Binary Signalling

Optimizing the Decoding Complexity of PEG-Based Methods with an Improved Hybrid Iterative/Gaussian Elimination Decoding Algorithm

This paper focuses on optimizing the decoding complexity of the progressive-edge-growth-based (PEG-based) method for the extended grouping of radio frequency identification (RFID) tags using a hybrid iterative/Gaussian elimination decoding algorithm. To further reduce the decoding time, the hybrid decoding is improved by including an early stopping criterion to avoid unnecessary iterations of iterative decoding for undecodable blocks. Various simulations have been carried out to analyse and assess the performance achieved with the PEG-based method under the improved hybrid decoding, both in terms of missing recovery capabilities and decoding complexities. Simulation results are presented, demonstrating that the improved hybrid decoding achieves the optimal missing recovery capabilities of full Gaussian elimination decoding at a lower complexity, as some of the missing tag identifiers are recovered iteratively

Multi-user indoor ultra-wideband wireless communication using polyphase spreading sequences.

http://digital-library.theiet.org/content/journals/10.1049/iet-com.2014.0131In this paper, we design a multi-user ultra-wideband system for indoor wireless communication. The proposed system is useful in multipath radio reception as the full multipath diversity gain is achieved. The system has multiple transmitters and receivers. They use polyphase spreading waveforms which feature low levels of mutual interference and enable each of the channel impulse responses to be measured free from distortion continuously with each data symbol transmission. A key feature of the proposed system is that transmitted waveforms are used which produce outputs from the receiver cross correlators, which are zero on both sides of the main correlation peak, for each radio path. This zero response lasts for a duration in excess of the expected delay spread of the radio channel enabling full Rake processing of the multipath signal. The effects of the low levels of mutual interference are reduced further by using time and frequency hopping, forward error correction and soft decision decoding

Inflammatory bowel diseases: principles of nutritional therapy Doenças inflamatórias intestinais: princípios da terapia nutricional

Inflammatory Bowel Diseases - ulcerative colitis and Crohn's disease- are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Total parenteral nutrition has been used to correct and to prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission in adults and promoting growth in children. Due to its low complication rate and lower costs, enteral nutrition should be preferred over total parenteral nutrition whenever possible. Both present equal effectiveness in primary therapy for remission of active Crohn's disease. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted, especially in patients presumed to need total parenteral nutrition. Recent research has focused on the use of nutrients as primary treatment agents. Immunonutrition is an important therapeutic alternative in the management of inflammatory bowel diseases, modulating the inflammation and changing the eicosanoid synthesis profile. However, beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these and other nutrients (glutamine, short-chain fatty acids, antioxidants) still need further evaluation through prospective and randomized trials.<br>As doenças inflamatórias intestinais - retocolite ulcerativa inespecífica e doença de Crohn - são afecções inflamatórias gastrointestinais crônicas de causa ainda desconhecida. Caracterizam-se por diarréia crônica, malabsorção, síndrome do intestino curto, disfunção da barreira mucosa e processo inflamatório intestinal, fatores que determinam deficiências nutricionais e funcionais que ressaltam a importância da terapia nutricional em seu tratamento. As diversas formas de terapia nutricional visam corrigir os distúrbios nutricionais e modular à resposta inflamatória, podendo, desta forma, influir na atividade da doença. A nutrição parenteral total tem sido usada para corrigir os distúrbios nutricionais e proporcionar repouso intestinal na doença ativa. Seu uso deve ser reservado a pacientes que não podem tolerar a nutrição enteral. A nutrição enteral é efetiva em induzir remissão clínica da doença em adultos e promover crescimento em crianças. Devido à baixa incidência de complicações e menor custo, a nutrição enteral deve ser opção preferencial à nutrição parenteral total quando possível. Ambas apresentam igual efetividade na terapia primária na remissão da Doença de Crohn ativa. Embora a terapia nutricional possa melhorar a evolução de muitos pacientes, é necessária uma seleção criteriosa devido a seus custos e complicações, especialmente naqueles que requerem nutrição parenteral total. Recentes pesquisas têm se dedicado ao uso de nutrientes como agentes terapêuticos primários. A imunonutrição com ácidos graxos ômega-3 se constitui numa importante alternativa terapêutica no manuseio das doenças inflamatórias intestinais, modulando o processo inflamatório e modificando o perfil de produção de eicosanóides. Entretanto, a real eficácia deste e outros nutrientes (glutamina, ácidos graxos de cadeia curta) ainda necessitam de novas avaliações por estudos prospectivos, controlados e randomizados