Anais do XX Simpósio Brasileiro de Telecomunicações最新文献

{"title":"The lambda-mi General Fading Distribution","authors":"G. Fraidenraich, M. Yacoub","doi":"10.14209/sbrt.2003.180","DOIUrl":"https://doi.org/10.14209/sbrt.2003.180","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131098226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Semi-Blind Beamspace-Time Interference Cancellation for a Multi- Code WCDMA System","authors":"I. Casella, P. Jeszensky, E. Sousa","doi":"10.14209/sbrt.2003.497","DOIUrl":"https://doi.org/10.14209/sbrt.2003.497","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127714114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Limites em Amplificadores Raman com Fibras Compensadoras de Dispersão","authors":"P. N. Cani, M. Freitas, R. T. R. Almeida, L. C. Calmon","doi":"10.14209/sbrt.2003.354","DOIUrl":"https://doi.org/10.14209/sbrt.2003.354","url":null,"abstract":"— This work investigates the limits of Raman amplification in counter-pumped systems with dispersion compensated fibers (DCF). Amplifiers in links with different lengths and in tandem are investigated. The length limits are obtained through signal to noise ratio and eye penalty analysis","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133596324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential Semi–Blind Spatial-Temporal Beamforming for DS–WCDMA Systems in Frequency Selective Time -Varying Channels","authors":"I. Casella, P. Jeszensky, E. Sousa","doi":"10.14209/sbrt.2003.515","DOIUrl":"https://doi.org/10.14209/sbrt.2003.515","url":null,"abstract":"In this paper , we propose a new differential semi-blind spatial-temporal beamforming receiver for asynchronous direct sequence wideband code division multiple access (DS-WCDMA) systems. The new receiver presents improved robustness to phase var iations and reduction of the effects of nonlinear distor tion. I . INTRODUCTION Although the main problem arising from high data rate DSWCDMA systems is the severe inter-symbol interference (ISI), in addition to the multiple access interference (MAI), the presence of a time-varying fading channel, even with a relative small Doppler spread (compared to the symbol duration), may also reduce overall system performance. In this situation, it may be convenient to employ differential encoding/decoding schemes. Using this simple approach, phase fluctuations in the received signal do not affect system performance as long as they can be considered negligible within a symbol interval. We note, however, that this robustness to channel variability is achieved at the expense of a higher signal-to-noise ratio (SNR). As we address the problem of differential detection, the method of data modulation considered is the π/4 shifted DQPSK, which eliminates the needs for accurate carrier recovery and greatly simplifies the implementation of the receiver. The choice is motivated by the efficiency of the method with respect to traditional QPSK or OQPSK, which require coherent detection [1]. Another advantage is that transitions in the signal constellation do not pass through the origin that reduces the effects of nonlinear distortion caused by the R.F. amplifier. This is obtained by the superposition of two QPSK signal constellations offset by 45 degrees relative to each other, resulting eight phases. The phases are alternatively selected from one of the two QPSK constellations [2]. In [3], a semi-blind spatial-temporal beamforming receiver (BST-SBCMACI) based on the SBCMACI (semi-blind constant modulus algorithm with channel identification) [4] was initially presented. The algorithm uses the constant modulus property of the transmitted signal and performs semi-blind subspace channel identification as a precursor to semi-blind equalization. The resulting receiver allows for coherent combination of the desired signal multipath, cancellation of the interfering users, removal of phase ambiguities present in blind algorithms and significant reduction of the required number of training symbols. In spite of all the advantages of this receiver, stationary conditions frame by frame are necessary. In order to relieve this requirement, we propose in this paper a new differential BST-SBCMACI receiver (BST-SBCMACI-DIFF) that presents improved robustness to phase variations and reduction of the effects of nonlinear distortion by employing π/4 shifted DQPSK data modulation and differential detection [2]. The paper is organized as follows: The system model is presented in section II; LS optimization and semi-blind subspace channel identificat","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116112250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of MIMO Systems with a Hybrid of Transmit Diversity and Spatial Multiplexing","authors":"J. Mota, A. Almeida, W. C. Freitas Jr., F. Cavalcanti","doi":"10.14209/sbrt.2003.639","DOIUrl":"https://doi.org/10.14209/sbrt.2003.639","url":null,"abstract":"Spatial multiplexing or BLAST (Bell Labs Layered Space-Time) and space-time block-coding (STBC) are promise approaches that exploits the MIMO channel to provide higher data rates and diversity gains with no sacrifice in bandwidth. In this work we evaluate the performance of a MIMO system that combines transmit diversity and spatial multiplexing schemes. We also propose two effective receiver structures for this hybrid transmission scheme. Our simulation results show that the performance of the hybrid scheme along with the proposed receivers is excellent, outperforming pure BLAST-based systems and with higher data rates than a pure STBC system. Keywords— Downlink, MIMO, transmit diversity and spatial multiplexing.","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114072581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Filtro de Partículas Ótimo para Rastreamento de Alvos Balísticos","authors":"A. Pavlov, M. G. D. S. Bruno","doi":"10.14209/sbrt.2003.722","DOIUrl":"https://doi.org/10.14209/sbrt.2003.722","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126307207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interference Managementfor WCDMA Systems Using SINR-Based Soft Handover and Smart Antennas","authors":"C. Lima, E. Rodrigues, V. Sousa Jr., F. Cavalcanti, A. Braga","doi":"10.14209/sbrt.2003.755","DOIUrl":"https://doi.org/10.14209/sbrt.2003.755","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130252014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Análise do Algoritmo LMS sujeito a uma Não-Linearidade do tipo Zona-Morta no Caminho Secundário","authors":"M. H. Costa, J. Bermudez","doi":"10.14209/sbrt.2003.704","DOIUrl":"https://doi.org/10.14209/sbrt.2003.704","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130536641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Greedy Algorithm for Reducing FWM Impairments in Dynamic Optical Networks","authors":"I. Fonseca, R. Almeida Jr., M. Ribeiro, H. Waldman","doi":"10.14209/sbrt.2003.121","DOIUrl":"https://doi.org/10.14209/sbrt.2003.121","url":null,"abstract":"(cid:151)This work presents a study on impact of Four Wave Mixing in dynamic optical networks. A simple algorithm is proposed in order to manage Four Wave Mixing impairments. Numerical results regarding blocking probability suggest that wavelength assignment should favor the wavelength with the smallest amount of noise. The limits for the use a simple greedy algorithm are tested. Although the algorithm clearly fails when network is severely impaired by FWM , signi(cid:2)cant improvements are achieved for low and moderate levels of FWM .","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124072768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Desempenho de Anéis WDM com Número Limitado de Transceptores por Nó","authors":"F. G. Lins, H. Waldman","doi":"10.14209/sbrt.2003.634","DOIUrl":"https://doi.org/10.14209/sbrt.2003.634","url":null,"abstract":"","PeriodicalId":325953,"journal":{"name":"Anais do XX Simpósio Brasileiro de Telecomunicações","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130625974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}