{"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}
P. N. Cani, M. Freitas, R. T. R. Almeida, L. C. Calmon
— 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
{"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}
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
本文提出了一种用于异步直接序列宽带码分多址(DS-WCDMA)系统的差分半盲时空波束形成接收机。该接收机对相位变化具有较强的鲁棒性，减少了非线性失真的影响。我。虽然高数据速率DSWCDMA系统产生的主要问题是严重的码间干扰(ISI)，但除了多址干扰(MAI)之外，时变衰落信道的存在，即使具有相对较小的多普勒扩频(与码长相比)，也可能降低系统的整体性能。在这种情况下，采用差分编码/解码方案可能比较方便。使用这种简单的方法，接收信号中的相位波动不会影响系统性能，只要它们在符号间隔内可以被认为是可以忽略不计的。然而，我们注意到，这种对信道可变性的鲁棒性是以更高的信噪比(SNR)为代价实现的。当我们解决差分检测问题时，考虑的数据调制方法是π/4移位DQPSK，它消除了对精确载波恢复的需求，并大大简化了接收机的实现。选择的动机是相对于传统的QPSK或OQPSK方法的效率，这需要相干检测[1]。另一个优点是信号星座中的过渡不经过原点，从而减少了射频放大器引起的非线性失真的影响。这是通过两个QPSK信号星座相互相对偏移45度的叠加得到的，结果是8个相位。相位可以从两个QPSK星座中选择一个[2]。文献[3]初步提出了一种基于SBCMACI(半盲恒模算法与信道识别)[4]的半盲时空波束形成接收机(BST-SBCMACI)。该算法利用传输信号的常模特性，进行半盲子空间信道识别，作为半盲均衡的先导。所得到的接收机允许所需信号多径的相干组合，消除干扰用户，消除盲算法中存在的相位模糊，并显着减少所需的训练符号数量。尽管这种接收机有种种优点，但是一帧一帧的固定条件是必要的。为了缓解这一需求，我们在本文中提出了一种新的差分BST-SBCMACI接收器(BST-SBCMACI- diff)，该接收器通过采用π/4位移DQPSK数据调制和差分检测，提高了对相位变化的鲁棒性，减少了非线性失真的影响[2]。本文的组织结构如下:第二节给出了系统模型;第三节LS优化与半盲子空间信道识别SBCMACI在第四节;第五节的模拟结果，最后是第六节的结束语。我们考虑异步DS-CDMA系统的反向链路，采用复杂扩频[5]和π/4-DQPSK数据调制来降低峰均比，并获得更好的相位变化鲁棒性。系统中有M个用户，在假设的平稳条件下，每个用户每包可以传输Nb个数据符号。还假设接收机采用由相同单元组成的天线阵列，其间隔为2个蚂蚁λ，其中蚂蚁λ为载波频率波长。假设逆信号带宽相对于在阵列上的传播时间较大，则在给定路径上，不同天线单元接收到的信号的复杂包络除了相位和幅度的差异(取决于路径到达角(AOA)、阵列几何形状和单元方向图)外是相同的[6]。第m个用户的第l个多径信号的AOA为l m θ， () l m θ a是阵列对从l m θ方向到达的多径信号的响应向量(空间特征向量)，其中()()()[]l m al m m a a θ θ θ，， 1 = a。我们可以用下面的矢量形式表示反向链路基带复信号:
{"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}
J. Mota, A. Almeida, W. C. Freitas Jr., F. Cavalcanti
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.
{"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}
C. Lima, E. Rodrigues, V. Sousa Jr., F. Cavalcanti, A. Braga
{"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}
I. Fonseca, R. Almeida Jr., M. Ribeiro, H. Waldman
(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 .
{"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}
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