http://hdl.handle.net/2117/3926 Thu, 23 May 2013 09:38:20 GMT 2013-05-23T09:38:20Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19377 Title: Designing national IP/MPLS networks with flexgrid optical technology Authors: Velasco Esteban, Luis Domingo; Wright, Paul; Lord, Andrew; Junyent Giralt, Gabriel Abstract: We propose a two-step procedure to design flexgrid-based national networks. Locations are first partitioned into a set of metro areas interconnected through a flexgrid optical network. Next, each network is designed separately. Optimal results show a future large (>200 nodes) flexgrid core network inter-connecting small (~10 nodes) metro regions. Thu, 23 May 2013 08:06:25 GMT http://hdl.handle.net/2117/19377 2013-05-23T08:06:25Z Velasco Esteban, Luis Domingo; Wright, Paul; Lord, Andrew; Junyent Giralt, Gabriel no Flexgrid optical networks We propose a two-step procedure to design flexgrid-based national networks. Locations are first partitioned into a set of metro areas interconnected through a flexgrid optical network. Next, each network is designed separately. Optimal results show a future large (>200 nodes) flexgrid core network inter-connecting small (~10 nodes) metro regions. http://hdl.handle.net/2117/19353 Title: A procedure to design wide-band electromagnetically-coupled stacked microstrip antennas based on a simple network model Authors: Anguera Pros, Jaume; Puente Baliarda, Carles; Borja, C. Abstract: It is well known that microstrip patch antennas have a poor bandwidth due to the small spacing between the patch and the ground plane. A stacked patch configuration has been demonstrated experimentally as a feasible solution, but little information on the design procedure is available. Here, a systematic design procedure based on a single network model is shown. Fri, 17 May 2013 16:31:23 GMT http://hdl.handle.net/2117/19353 2013-05-17T16:31:23Z Anguera Pros, Jaume; Puente Baliarda, Carles; Borja, C. no Antenna radiation patterns, electromagnetic coupling, microstrip antennas It is well known that microstrip patch antennas have a poor bandwidth due to the small spacing between the patch and the ground plane. A stacked patch configuration has been demonstrated experimentally as a feasible solution, but little information on the design procedure is available. Here, a systematic design procedure based on a single network model is shown. http://hdl.handle.net/2117/19352 Title: Iterative network models to predict the performance of Sierpinski fractal antennas and networks Authors: Borja, C.; Puente Baliarda, Carles Abstract: Two simple, fast numerical models to predict the input parameters of antennas and networks whose topologies are that of the Sierpinski gasket and carpet fractal shape, are introduced. These models are based on the same recursive principle used to generate fractal structures. Fri, 17 May 2013 16:28:53 GMT http://hdl.handle.net/2117/19352 2013-05-17T16:28:53Z Borja, C.; Puente Baliarda, Carles no Two simple, fast numerical models to predict the input parameters of antennas and networks whose topologies are that of the Sierpinski gasket and carpet fractal shape, are introduced. These models are based on the same recursive principle used to generate fractal structures. http://hdl.handle.net/2117/19350 Title: ONU optimal gain and position of the distribution element in Rayleigh-limited WDM and TDM PONs with reflective ONU Authors: López Pastor, Eduardo Tommy; Lázaro Villa, José Antonio; Arellano Pinilla, Cristina; Polo Querol, Víctor; Prat Gomà, Josep Joan Abstract: The influence of the distribution element position in PONs is reported. Best Crosstalk-to-Signal ratio (C/S) is achieved if it is placed either in the ONU or OLT vicinity with optimum ONU gain depending of the MUX position Fri, 17 May 2013 14:55:56 GMT http://hdl.handle.net/2117/19350 2013-05-17T14:55:56Z López Pastor, Eduardo Tommy; Lázaro Villa, José Antonio; Arellano Pinilla, Cristina; Polo Querol, Víctor; Prat Gomà, Josep Joan no The influence of the distribution element position in PONs is reported. Best Crosstalk-to-Signal ratio (C/S) is achieved if it is placed either in the ONU or OLT vicinity with optimum ONU gain depending of the MUX position http://hdl.handle.net/2117/19341 Title: Real time 100 GHz MST imaging retina Authors: Alonso del Pino, María; Garg, V.; Garcia Guerra, Carlos Enrique; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís Abstract: A real time tomographic imaging system at 100 GHz based on a retina and Modulated Scattered Technique (MST) is presented in this paper. It consists in applying a low frequency modulation to each probe of an array of antennas in order to coherently detect the electric field by a collector. This system just requires low frequency wiring and reduces the RF equipment necessary for each pixel for a planar surface. The aim of this paper is to analyze the performance of different tomographic imaging processes for the imaging system described. Fri, 17 May 2013 13:52:47 GMT http://hdl.handle.net/2117/19341 2013-05-17T13:52:47Z Alonso del Pino, María; Garg, V.; Garcia Guerra, Carlos Enrique; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís no antenna design, imaging reconstruction, imaging system, MST, Real time, Retina, THz, tomography A real time tomographic imaging system at 100 GHz based on a retina and Modulated Scattered Technique (MST) is presented in this paper. It consists in applying a low frequency modulation to each probe of an array of antennas in order to coherently detect the electric field by a collector. This system just requires low frequency wiring and reduces the RF equipment necessary for each pixel for a planar surface. The aim of this paper is to analyze the performance of different tomographic imaging processes for the imaging system described. http://hdl.handle.net/2117/19340 Title: Stability of the MIRAS amplitude calibration Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. Fri, 17 May 2013 13:43:19 GMT http://hdl.handle.net/2117/19340 2013-05-17T13:43:19Z Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel no Radiometer calibration, Accurate modeling, Amplitude calibration, Antenna temperature, Internal calibration, Radiometer calibration, Receiver front-ends Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. http://hdl.handle.net/2117/19330 Title: Optimal linear correction in LMMSE estimation using moments of the complex inverse Wishart distribution Authors: Serra, Jordi; Nájar Martón, Montserrat Abstract: The conventional linear minimum mean square error esti- mator (LMMSE) suffers a severe performance degradation whenever the sample size is comparable to the observation dimension. In order to tackle this problem, we propose an optimal linear correction of the conventional LMMSE, which minimizes the average mean square error (MSE) by using the moments of the complex inverse Wishart distribution. Numerical simulations highlight that the proposed estimator dramatically outperforms the conventional LMMSE in the small sample size regime Fri, 17 May 2013 12:04:30 GMT http://hdl.handle.net/2117/19330 2013-05-17T12:04:30Z Serra, Jordi; Nájar Martón, Montserrat no Complex Inverse Wishart, LMMSE, Shrinkage, Small sample size The conventional linear minimum mean square error esti- mator (LMMSE) suffers a severe performance degradation whenever the sample size is comparable to the observation dimension. In order to tackle this problem, we propose an optimal linear correction of the conventional LMMSE, which minimizes the average mean square error (MSE) by using the moments of the complex inverse Wishart distribution. Numerical simulations highlight that the proposed estimator dramatically outperforms the conventional LMMSE in the small sample size regime http://hdl.handle.net/2117/19329 Title: Licensing open spectrum systems Authors: Vázquez, Miguel Angel; Pérez Neira, Ana Isabel; Lagunas Hernandez, Miguel A. Abstract: This paper studies how the spectrum regulation could change in the future open spectrum communication systems. Due to their huge success in short-range communication systems (WiFi, Zigbee, ...), broader area telecommunication providers might mimic the open spectrum philosophy to their systems. Nevertheless, current wireless open spectrum systems are not designed for wide areas and they do not provide QoS to their users. This work proposes an alternative to the nowadays open spectrum systems in order to fulfill those requirements. Optimal power transmission strategies are derived. Numerical results show the performance of our proposal. Fri, 17 May 2013 12:00:36 GMT http://hdl.handle.net/2117/19329 2013-05-17T12:00:36Z Vázquez, Miguel Angel; Pérez Neira, Ana Isabel; Lagunas Hernandez, Miguel A. no Numerical results, Optimal power, Short-range communication, Spectrum communications, Spectrum regulation, Spectrum systems, Telecommunication providers, Transmission strategies, Wide area This paper studies how the spectrum regulation could change in the future open spectrum communication systems. Due to their huge success in short-range communication systems (WiFi, Zigbee, ...), broader area telecommunication providers might mimic the open spectrum philosophy to their systems. Nevertheless, current wireless open spectrum systems are not designed for wide areas and they do not provide QoS to their users. This work proposes an alternative to the nowadays open spectrum systems in order to fulfill those requirements. Optimal power transmission strategies are derived. Numerical results show the performance of our proposal. http://hdl.handle.net/2117/19328 Title: Simulation of LTE IR H-ARQ at system level using MIESM error prediction Authors: Olmos Bonafé, Juan José; Serra, Albert; García Lozano, Mario; Ruiz Boqué, Sílvia; Pérez Díaz de Cerio, David Fri, 17 May 2013 11:30:15 GMT http://hdl.handle.net/2117/19328 2013-05-17T11:30:15Z Olmos Bonafé, Juan José; Serra, Albert; García Lozano, Mario; Ruiz Boqué, Sílvia; Pérez Díaz de Cerio, David no http://hdl.handle.net/2117/19327 Title: Cooperative communications: from theory to experimental implementation Authors: Alonso-Zárate, Jesús; Sanchez Recacha, Javier; Zorba, Nizar; Pérez Neira, Ana Isabel; Verikoukis, Christos Abstract: Over the last years, cooperative communications have been studied from both fundamental and practical points of view. However, most of the existing studies of cooperative communications rely on math or computer simulation. In this paper, we describe the implementation of a cooperative communication strategy for wireless networks in a testbed based on Click Modular Router. We describe the methodology we have followed to reprogram the drivers controlling the data layer functions of off-the-shelf commercial Wireless Network Interface Cards (NICs). More precisely, we have implemented a Cooperative Automatic Retransmission (C-ARQ) scheme to show that the performance of wireless communications can be boosted by using an intermediate relay when the wireless channel between the source and the destination is in bad conditions. The results presented in this paper are promising, as they show that previous theory and simulation results presented in the literature can become true in a real implementation. Fri, 17 May 2013 10:46:10 GMT http://hdl.handle.net/2117/19327 2013-05-17T10:46:10Z Alonso-Zárate, Jesús; Sanchez Recacha, Javier; Zorba, Nizar; Pérez Neira, Ana Isabel; Verikoukis, Christos no Over the last years, cooperative communications have been studied from both fundamental and practical points of view. However, most of the existing studies of cooperative communications rely on math or computer simulation. In this paper, we describe the implementation of a cooperative communication strategy for wireless networks in a testbed based on Click Modular Router. We describe the methodology we have followed to reprogram the drivers controlling the data layer functions of off-the-shelf commercial Wireless Network Interface Cards (NICs). More precisely, we have implemented a Cooperative Automatic Retransmission (C-ARQ) scheme to show that the performance of wireless communications can be boosted by using an intermediate relay when the wireless channel between the source and the destination is in bad conditions. The results presented in this paper are promising, as they show that previous theory and simulation results presented in the literature can become true in a real implementation. http://hdl.handle.net/2117/19326 Title: Performance of a spatial error correction technique in SMOS brightness temperature images Authors: Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. Fri, 17 May 2013 10:19:57 GMT http://hdl.handle.net/2117/19326 2013-05-17T10:19:57Z Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel no Performance of a spatial error correction technique in SMOS brightness temperature images Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. http://hdl.handle.net/2117/19297 Title: Cramer-rao bound for time-delay estimation in the frequency domain Authors: Serra, Jordi; Blanco, Luis; Nájar Martón, Montserrat Abstract: In this paper a measure of performance of time delay estimators arising from a frequency model of the received signal is presented. The aim is to derive theoretical analysis of the Cramer-Rao bound (CRB) for time delay estimation under realistic wireless channel propagation conditions. The derivation of the CRB is considered from the frequency domain signal model yielding a closed-form expression without imposing any constraints on the different propagation paths. Thu, 16 May 2013 12:45:41 GMT http://hdl.handle.net/2117/19297 2013-05-16T12:45:41Z Serra, Jordi; Blanco, Luis; Nájar Martón, Montserrat no In this paper a measure of performance of time delay estimators arising from a frequency model of the received signal is presented. The aim is to derive theoretical analysis of the Cramer-Rao bound (CRB) for time delay estimation under realistic wireless channel propagation conditions. The derivation of the CRB is considered from the frequency domain signal model yielding a closed-form expression without imposing any constraints on the different propagation paths. http://hdl.handle.net/2117/19296 Title: A unifying approach to transmit beamforming for the MISO interference channel Authors: Vázquez, Miguel Angel; Pérez Neira, Ana Isabel; Lagunas Hernandez, Miguel A. Abstract: This paper addresses the problem of optimal beam- forming in the MISO interference channel. Different approaches are known to obtain the Pareto rate region. In this paper, several frameworks are thoroughly analyzed and compared. It is shown that there is an equivalence between all methods. Indeed, we show that they are different scalarization techniques of the same vector objective optimization problem. The results provide a bridge between the frameworks which were studied separately in the literature. Numerical simulations validate our theoretical findings Thu, 16 May 2013 12:39:31 GMT http://hdl.handle.net/2117/19296 2013-05-16T12:39:31Z Vázquez, Miguel Angel; Pérez Neira, Ana Isabel; Lagunas Hernandez, Miguel A. no Interference channels, Objective optimization, Optimal beamforming, Scalarization, Transmit beamforming This paper addresses the problem of optimal beam- forming in the MISO interference channel. Different approaches are known to obtain the Pareto rate region. In this paper, several frameworks are thoroughly analyzed and compared. It is shown that there is an equivalence between all methods. Indeed, we show that they are different scalarization techniques of the same vector objective optimization problem. The results provide a bridge between the frameworks which were studied separately in the literature. Numerical simulations validate our theoretical findings http://hdl.handle.net/2117/19292 Title: MM-wave scattering measurements for imaging and channel characterization Authors: Toda, A.P.; de Flaviis, Franco; Jofre Roca, Lluís; Romeu Robert, Jordi Abstract: In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained. Thu, 16 May 2013 12:23:28 GMT http://hdl.handle.net/2117/19292 2013-05-16T12:23:28Z Toda, A.P.; de Flaviis, Franco; Jofre Roca, Lluís; Romeu Robert, Jordi no imaging, Lens antenna, mm-wave, scatterer mapping, V-Band In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained. http://hdl.handle.net/2117/19290 Title: Mitigation of the finger loading effect in handset antennas Authors: Anguera Pros, Jaume; Andujar, Aurora; Camps, Albert; Puente Baliarda, Carles; Picher, Cristina Abstract: The effect of the human body over the radiation of handset antennas is a critical issue that have to be considered to ensure a good handset antenna performance. Among the human body effect, the finger is of particular interest since it is usually placed over the antenna area which may cause detuning and/or reduction of the efficiency. To mitigate the finger loading effects, a novel handset antenna consisting of two small antennas distributed along the ground plane is proposed. The distributed antenna system is compared with a single antenna having a broadband matching network, so both designs feature enough bandwidth to cover the GSM850 (824-890MHz) and GSM900 (880-960MHz) communication systems. The finger effect is analyzed in terms of efficiency using a phantom hand. Efficiency is measured for different finger locations concluding that the distributed antenna system is more robust to the finger loading effect. Thu, 16 May 2013 12:13:24 GMT http://hdl.handle.net/2117/19290 2013-05-16T12:13:24Z Anguera Pros, Jaume; Andujar, Aurora; Camps, Albert; Puente Baliarda, Carles; Picher, Cristina no The effect of the human body over the radiation of handset antennas is a critical issue that have to be considered to ensure a good handset antenna performance. Among the human body effect, the finger is of particular interest since it is usually placed over the antenna area which may cause detuning and/or reduction of the efficiency. To mitigate the finger loading effects, a novel handset antenna consisting of two small antennas distributed along the ground plane is proposed. The distributed antenna system is compared with a single antenna having a broadband matching network, so both designs feature enough bandwidth to cover the GSM850 (824-890MHz) and GSM900 (880-960MHz) communication systems. The finger effect is analyzed in terms of efficiency using a phantom hand. Efficiency is measured for different finger locations concluding that the distributed antenna system is more robust to the finger loading effect.