Pub Date : 2019-11-01DOI: 10.1109/LATINCOM48065.2019.8937882
Washington Medina, Francisco Novillo, Eduardo Chancay, Juan M. Romero-Arguello
The future high demand for wireless services, especially inside smart buildings located in dense urban areas, and the possible saturation of the spectrum used by short-range wireless systems have allowed the search for solutions based on the Dynamic Spectrum Access model. Cognitive Radio system is a proposed solution; it works allowing that an incumbent operator share their available assigned spectrum with other service operator, in order to improve the efficiency on the spectrum use. To know only the availability of an electromagnetic spectrum segment is not enough so there are to check that their use by other operator does not affect to the surrounding incumbent users (e.g. a building inner incumbent users). The objective of this study is to characterize by simulation process the minimal effective spectral availability inside large buildings assuming a deployment of the incumbent system users in their inner, taking in account the shadowing phenomena influence too. The results show that the effective spectral availability is distributed on the 60% smart building inner area for large buildings, and it could decrease between 30% and 40% depending on the shadowing level and the distance from transmitter.
{"title":"Characterizing Effective Spectral Opportunities and Shadowing Influence Inside Large Buildings for Short Range CRWS Use","authors":"Washington Medina, Francisco Novillo, Eduardo Chancay, Juan M. Romero-Arguello","doi":"10.1109/LATINCOM48065.2019.8937882","DOIUrl":"https://doi.org/10.1109/LATINCOM48065.2019.8937882","url":null,"abstract":"The future high demand for wireless services, especially inside smart buildings located in dense urban areas, and the possible saturation of the spectrum used by short-range wireless systems have allowed the search for solutions based on the Dynamic Spectrum Access model. Cognitive Radio system is a proposed solution; it works allowing that an incumbent operator share their available assigned spectrum with other service operator, in order to improve the efficiency on the spectrum use. To know only the availability of an electromagnetic spectrum segment is not enough so there are to check that their use by other operator does not affect to the surrounding incumbent users (e.g. a building inner incumbent users). The objective of this study is to characterize by simulation process the minimal effective spectral availability inside large buildings assuming a deployment of the incumbent system users in their inner, taking in account the shadowing phenomena influence too. The results show that the effective spectral availability is distributed on the 60% smart building inner area for large buildings, and it could decrease between 30% and 40% depending on the shadowing level and the distance from transmitter.","PeriodicalId":120312,"journal":{"name":"2019 IEEE Latin-American Conference on Communications (LATINCOM)","volume":"519 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123412072","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}
Pub Date : 2019-11-01DOI: 10.1109/LATINCOM48065.2019.8938008
Nicolás M. Ortega, César A. Azurdia-Meza, C. Gutiérrez, C. A. Gómez-Vega
Vehicular communication networks that may improve road safety are generating wide interest. As some vehicular networks use the radio frequency medium, channel estimation is crucial. Most channel estimation techniques are designed assuming the Wide Sense Stationary Uncorrelated Scattering (WSSUS) condition for the channel model. However, several measurement campaigns carried out around the world suggest that the WSSUS assumption might not hold in a vehicular environment. In this paper, we use simulations to compare the performance of two IEEE 802.11p-based Channel Estimation techniques in terms of Bit Error Rate (BER) with a channel model that is non-WSSUS. The selected channel model allows velocity variations on the mobiles. We compare the BER results of the estimation schemes varying the value of parameters related to the Doppler effect, namely, acceleration of the mobiles and the distance between them. Our results show that the nonstationarities caused by the Doppler effect are the main cause of the degradation of the system performance. We use the Four-Dimensional Time-Frequency Correlation Function to give prior insights on how the BER performance behaves. Also, we show that the BER performance of time-frequency estimation schemes, such as that of the Spectral Time Averaging technique, is strongly affected by the distance between the mobiles, but not by the accelerations of or the trajectory of these. On the other hand, we show that the BER performance of time interpolation only schemes, such as the Least Square technique, is not affected by the distance between the mobiles or the accelerations of them.
{"title":"Second Order Statistics and BER Performance Analysis of a non-WSSUS V2X Channel Model that Considers Velocity Variations","authors":"Nicolás M. Ortega, César A. Azurdia-Meza, C. Gutiérrez, C. A. Gómez-Vega","doi":"10.1109/LATINCOM48065.2019.8938008","DOIUrl":"https://doi.org/10.1109/LATINCOM48065.2019.8938008","url":null,"abstract":"Vehicular communication networks that may improve road safety are generating wide interest. As some vehicular networks use the radio frequency medium, channel estimation is crucial. Most channel estimation techniques are designed assuming the Wide Sense Stationary Uncorrelated Scattering (WSSUS) condition for the channel model. However, several measurement campaigns carried out around the world suggest that the WSSUS assumption might not hold in a vehicular environment. In this paper, we use simulations to compare the performance of two IEEE 802.11p-based Channel Estimation techniques in terms of Bit Error Rate (BER) with a channel model that is non-WSSUS. The selected channel model allows velocity variations on the mobiles. We compare the BER results of the estimation schemes varying the value of parameters related to the Doppler effect, namely, acceleration of the mobiles and the distance between them. Our results show that the nonstationarities caused by the Doppler effect are the main cause of the degradation of the system performance. We use the Four-Dimensional Time-Frequency Correlation Function to give prior insights on how the BER performance behaves. Also, we show that the BER performance of time-frequency estimation schemes, such as that of the Spectral Time Averaging technique, is strongly affected by the distance between the mobiles, but not by the accelerations of or the trajectory of these. On the other hand, we show that the BER performance of time interpolation only schemes, such as the Least Square technique, is not affected by the distance between the mobiles or the accelerations of them.","PeriodicalId":120312,"journal":{"name":"2019 IEEE Latin-American Conference on Communications (LATINCOM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129837382","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}
Pub Date : 2019-11-01DOI: 10.1109/LATINCOM48065.2019.8937980
A. Ortega, R. Neto, R. David
We propose a hybrid precoder for downnlik mmWave massive MU-MIMO system designed through the maximization of the mutual information' upper bound. The methodology of a large number of the hybrid precoder proposed in the literature is focused on finding a hybrid approximation to a digital precoder. However, for our proposed design a known signal processing methodology for traditional MIMO is adapted to mmWave scenarios. Numerical results in terms of mutual information rate show a performance improvement obtained by our proposal in relation to others considered hybrid precoders.
{"title":"Novel hybrid precoder based on SVD for downlink mmWave massive MU-MIMO systems","authors":"A. Ortega, R. Neto, R. David","doi":"10.1109/LATINCOM48065.2019.8937980","DOIUrl":"https://doi.org/10.1109/LATINCOM48065.2019.8937980","url":null,"abstract":"We propose a hybrid precoder for downnlik mmWave massive MU-MIMO system designed through the maximization of the mutual information' upper bound. The methodology of a large number of the hybrid precoder proposed in the literature is focused on finding a hybrid approximation to a digital precoder. However, for our proposed design a known signal processing methodology for traditional MIMO is adapted to mmWave scenarios. Numerical results in terms of mutual information rate show a performance improvement obtained by our proposal in relation to others considered hybrid precoders.","PeriodicalId":120312,"journal":{"name":"2019 IEEE Latin-American Conference on Communications (LATINCOM)","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115023956","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}
Pub Date : 2019-08-16DOI: 10.1109/LATINCOM48065.2019.8937874
F. A. P. Figueiredo, C. Dias, E. Lima, G. Fraidenraich
Accurate channel estimation is of utmost importance for massive MIMO systems that allow providing significant improvements in spectral and energy efficiency. In this work, we investigate the spectral efficiency performance and present a channel estimator for multi-cell massive MIMO systems subjected to pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without prior knowledge of the inter-cell large-scale channel coefficients and noise power. The estimator approximates the performance of a linear Minimum Mean Square Error (MMSE) as the number of antennas increases. Following, we derive a lower bound closed-form spectral efficiency of the Maximum Ratio Combining (MRC) detector in the proposed channel estimator. The simulation results highlight that the proposed estimator performance approaches the linear minimum mean square error (LMMSE) channel estimator asymptotically.
{"title":"Performance Analysis of Large-Scale MU-MIMO with a Simple and Effective Channel Estimator","authors":"F. A. P. Figueiredo, C. Dias, E. Lima, G. Fraidenraich","doi":"10.1109/LATINCOM48065.2019.8937874","DOIUrl":"https://doi.org/10.1109/LATINCOM48065.2019.8937874","url":null,"abstract":"Accurate channel estimation is of utmost importance for massive MIMO systems that allow providing significant improvements in spectral and energy efficiency. In this work, we investigate the spectral efficiency performance and present a channel estimator for multi-cell massive MIMO systems subjected to pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without prior knowledge of the inter-cell large-scale channel coefficients and noise power. The estimator approximates the performance of a linear Minimum Mean Square Error (MMSE) as the number of antennas increases. Following, we derive a lower bound closed-form spectral efficiency of the Maximum Ratio Combining (MRC) detector in the proposed channel estimator. The simulation results highlight that the proposed estimator performance approaches the linear minimum mean square error (LMMSE) channel estimator asymptotically.","PeriodicalId":120312,"journal":{"name":"2019 IEEE Latin-American Conference on Communications (LATINCOM)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130287087","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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