Papers by Graciela Corral-Briones
2017 XVII Workshop on Information Processing and Control (RPIC), 2017
The development of air-to-ground multiple-input multiple-output (MIMO) channel models is required... more The development of air-to-ground multiple-input multiple-output (MIMO) channel models is required to design high throughput and efficient signal communication schemes, in order to satisfy the communication demands on a new challenging air-to-ground scenarios. To this objective, a deep understanding of communication channel behavior is required. In this context, this paper analyzes a propagation-motivated MIMO metrics on a recently proposed three-dimensional (3D) reference MIMO channel model originally designed for high altitude platforms. We present results of ergodic capacity, effective diversity, and eigenvalue distribution for an Unmanned Aerial Vehicle (UAV) air-to-ground communication link in a circularly flight mission, showing that there is some multiplexing gain even with persistent Line-Of-Sight (LOS) signal presence, besides the expected MIMO power gain.
We investigate the performance of channel-aware scheduling algorithms designed for the downlink o... more We investigate the performance of channel-aware scheduling algorithms designed for the downlink of a wireless communication system. Our study focuses on a two-transmit antenna cellular system, where the base station can only rely on quantized versions of channel state information to carry out scheduling decisions. The motivation is to study the interaction between throughput and fairness of practical spatial multiplexing schemes when implemented using existing physical layer signaling, such as the one that exists in current wideband code division multiple access downlink. Virtual MIMO system selects at each time instant a pair of users that report orthogonal (quantized) channels. Closed-form expressions for the achievable sum-rate of three different channelaware scheduling rules are presented using an analytical framework that is derived in this work. Our analysis reveals that simple scheduling procedures allow to reap a large fraction (in the order of 80%) of the sum-rate performan...
El proyecto esta basado en la investigacion y desarrollo de sistemas de comunicaciones digitales ... more El proyecto esta basado en la investigacion y desarrollo de sistemas de comunicaciones digitales inalambricos, dentro del campo de las telecomunicaciones, encarando como aspecto distintivo la prestacion de servicios integrados es decir, la posibilidad de acceder a voz, video y datos a traves de un solo medio. Este tipo de comunicaciones se denomina multimedio y es posible debido a adelantos tecnologicos en el area de integracion de circuitos, la difusion en el uso de computadoras y el creciente avance de los servicios de las empresas prestadoras. Los sistemas inalambricos de comunicaciones multimedio requieren frecuentemente la transmision de senales codificadas, las cuales pueden representar audio, video, imagenes estaticas, datos, etc. (...) El desvanecimiento de Rayleigh y las multitrayectorias de la senal en un sistema inalambrico de comunicaciones, causa la perdida de componentes de esa senal. Tecnicas tales como el uso de codigos de correccion de errores, requisicion automatic...
IEEE International Conference on Communications, 2005. ICC 2005. 2005
Previous works have shown that in case of multiple transmit antenna broadcast channels, the total... more Previous works have shown that in case of multiple transmit antenna broadcast channels, the total system throughput can be greatly improved by combining spatial prefiltering (SP) with multiuser scheduling (MS) [G. Caire et al., 2003], [D. Samardzija et al., 2003]. However, most of the studies assume full channel state information at the transmitter (CSIT). In this paper, we study the
2007 IEEE International Conference on Communications, 2007
We study the performance of fair physical layer schedulers that select a pair of orthogonal users... more We study the performance of fair physical layer schedulers that select a pair of orthogonal users for simultaneous transmission. The schemes rely on partial channel state information compatible with 3GPP specifications and differ with respect to their usage of channel quality indicator in scheduling decisions. Closed-form expressions for the achievable sum-rate of three practical scheduling algorithms are derived.
WCNC. 1999 IEEE Wireless Communications and Networking Conference (Cat. No.99TH8466)
ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)
We propose a new reduced-complexity multiuser receiver for asynchronous trellis-coded CDMA system... more We propose a new reduced-complexity multiuser receiver for asynchronous trellis-coded CDMA systems in AWGN channels. Based on the coding information of a subset of users and the set partitioning principles inherent in TCM, reduced-state trellises are constructed. The Viterbi algorithm is thus used to jointly decode the trellis codes of this subset of users and equalize the multiuser interference of
Proceedings IEEE 56th Vehicular Technology Conference
Optimal multiuser detection of trellis coded signals has prohibitive complexity. A suboptimal con... more Optimal multiuser detection of trellis coded signals has prohibitive complexity. A suboptimal concatenated scheme consisting of a maximum a posteriori (MAP) multiuser interference (MUI) detector followed by a deinterleaver and a soft trellis decoder has recently received considerable attention in the literature. We call this scheme concatenated multiuser detector and trellis decoder (CMDTD). An alternative to CMDTD is joint multiuser
2002 IEEE Wireless Communications and Networking Conference Record. WCNC 2002 (Cat. No.02TH8609)
Space-time coding (STC) is an efficient technique to combat severe fading effects and improve sys... more Space-time coding (STC) is an efficient technique to combat severe fading effects and improve system capacity in wireless communications. However, for CDMA communications, multi-antenna transmission increases the multiuser interference (MUI). In addition, if the data rate is high, the processing gain can be quite small, and thus the MUI is further enhanced. In this paper we propose a new non-iterative
IEEE Transactions on Communications, 2006
Reduced-complexity multiuser interference equalization and group decoding (ME-GD) is an attractiv... more Reduced-complexity multiuser interference equalization and group decoding (ME-GD) is an attractive way to improve performance of multiuser transmissions for narrowband additive white Gaussian noise channels. ME-GD receivers have been investigated in the past for convolutionally coded synchronous multiple-access channels (MACs). In this paper, we propose a new ME-GD for trellis-coded asynchronous MACs. The coding information of a subset of users and the multiuser interference are jointly taken into account in the branch metric computation using per-survivor processing. The novel approach leads to a family of Viterbi decoders which offers a good tradeoff between performance and complexity. As a second contribution of this paper, we derive theoretical bounds for the performance of ME-GD considering the effect of error propagation, which is critical for asynchronous MACs. Numerical results show the excellent accuracy of the proposed bounds. Finally, based on the novel theoretical analysis, we derive a new criterion to achieve good tradeoffs between performance and complexity. Index Terms-Equalizers, multiuser channels, trellis codes, Viterbi decoding. I. INTRODUCTION M ULTIUSER detection and error-control coding are used to improve performance of multiple-access channels (MACs). For the case of bandlimited code-division multiple-access (CDMA) channels, it has been shown that multiuser receivers with convolutional codes achieve little performance improvement over an uncoded system [1], [2]. This is because convolutional codes require a spreading-gain reduction in order to keep the same bandwidth as an uncoded system, thus increasing the effective interference. Conversely, trellis codes (which do not require a reduction of the spreading ratio) perform very well, and have been proposed as the best choice for fixed bandwidth multiuser CDMA systems [1]-[3].
IEEE Photonics Technology Letters, 2013
Frequency fluctuations caused by mechanical vibrations, power supply noise, and other mechanisms ... more Frequency fluctuations caused by mechanical vibrations, power supply noise, and other mechanisms are detrimental to the phase estimator performance in high speed intradyne coherent optical receivers. In this letter, we propose the use of a low-latency parallel digital phase lock loop in combination with common feed-forward carrier phase recovery algorithms in order to compensate both the phase noise and laser frequency fluctuation effects on 16-quadrature amplitude modulation receivers. Numerical results demonstrate the excellent behavior of the proposed two-stage carrier recovery scheme.
The 5th International Symposium on Wireless Personal Multimedia Communications
The combination of space-time coding (STC) techniques and multiuser detection is a promising appr... more The combination of space-time coding (STC) techniques and multiuser detection is a promising approach to increase the spectral efficiency of multiple-access channels. We present a theoretical performance analysis of multiuser receivers for space time coded DS-CDMA systems. We study the performance of the maximum-likelihood multiuser receiver (MLMR) for a set of asynchronous independent users communicating with the base station. The
2019 XVIII Workshop on Information Processing and Control (RPIC)
In this paper we analyze the integration of a digital clock and data recovery with a Viterbi deco... more In this paper we analyze the integration of a digital clock and data recovery with a Viterbi decoder and propose a new interface module that minimizes the detrimental effects of clock jitter on decoded data. The proposed interface avoids decoder idle times and the utilization of a faster clock, optimizing the power consumption. A detailed performance analysis shows that jitter effects on decoding data can be practically eliminate with an appropriate design of the proposed interface.
2017 XLIII Latin American Computer Conference (CLEI), 2017
As small satellites become more capable through miniaturized electronics and on-board processing,... more As small satellites become more capable through miniaturized electronics and on-board processing, constellations of low-cost satellites lunched in Low-Earth Orbit (LEO) become feasible. The increase in the number of LEO satellites drives the need for frequency coexistence between the LEO constellation systems with the already existing geostationary (GSO) satellite networks. In this context, it is crucial to design the communication links paying special attention to interference analysis. This is particularly true when the LEO satellite constellation exploit inter-satellite communication links (ISL). In this paper, a radio frequency interference analysis based on simulation of the dynamic satellite constellation is presented and the design parameters of the inter-satellite links are analyzed. The results suggest that carefully choosing the design parameters of the intersatellite links, spectrum coexistence of LEO and GSO networks may be possible.
IEEE Open Journal of the Communications Society, 2021
Increasing the availability of Unmanned Aerial Vehicles (UAV's) platforms leads to a variety of a... more Increasing the availability of Unmanned Aerial Vehicles (UAV's) platforms leads to a variety of applications for aerial exploration, surveillance, and transport. Many of these applications rely on the communication between the UAV and the ground receiver which is subjected to high mobility that may lead to restrictions on link connectivity and throughput. In order to design high throughput and efficient communication schemes for these scenarios, a deep understanding of the communication channel behavior is required, especially taking into account measurement data from flight experiments. Channel propagation in urban environments involves diffraction effects which modify the Line-of-Sight (LoS) contribution of the total received signal, especially when the receiver is located on the ground. This process leads to scenarios where Multiple-Input Multiple-Output (MIMO) signal processing can take advantage from this situation. In this context, the goal of this paper is to study the diffraction effects of the LoS component through spatial correlation metrics of the signal. To accomplish this, we propose the use of a geometric stochastic technique to model the channel behavior which lies between High Altitude Platforms (HAP) and terrestrial link communications. INDEX TERMS MIMO, unmanned aerial vehicles, channel model, air-to-ground. HORACIO A. MENDOZA received the Electronic Engineering degree from the National University of Misiones (UnaM), Misiones, Argentina, in 2004, and the Master of Science in Engineering degree from the National University of Cordoba, Argentina, in 2012. He is currently serving as a Professor and Researcher with the Digital Communication Laboratory (LCD), Universidad Nacional de Córdoba. Also is currently serving as a Researcher of the Grupo de Investigación y Desarrollo en Ingeniería Electrónica (GIDIE) with the Department of Electronic Engineering of the UNaM. His research interests lie in the fields of channel modeling and measurements and advanced digital modulation/reception techniques for MIMO Wireless Communication.
El crecimiento exponencial del trafico de datos es uno de los mayores desafios que enfrentan actu... more El crecimiento exponencial del trafico de datos es uno de los mayores desafios que enfrentan actualmente los sistemas de comunicaciones, debiendo los mismos ser capaces de soportar velocidades de procesamiento de datos cada vez mas altas. En particular, el consumo de potencia se ha transformado en uno de los parametros de diseno mas criticos, generando la necesidad de investigar el uso de nuevas arquitecturas y algoritmos para el procesamiento digital de la informacion. Por otro lado, el analisis y evaluacion de nuevas tecnicas de procesamiento presenta dificultades dadas las altas velocidades a las que deben operar, resultando frecuentemente ineficiente el uso de la simulacion basada en software como metodo. En este contexto, el uso de electronica programable ofrece una oportunidad a bajo costo donde no solo se evaluan nuevas tecnicas de diseno de alta velocidad sino tambien se valida su implementacion en desarrollos tecnologicos. El presente proyecto tiene como objetivo principal ...
2018 IEEE 23rd International Conference on Digital Signal Processing (DSP), 2018
Data dissemination using Unmanned Aerial Vehicles (UAVs) is currently emerging as an alternative ... more Data dissemination using Unmanned Aerial Vehicles (UAVs) is currently emerging as an alternative to effectively integrate remote devices to Internet of Things core networks. This paper proposes the use of a closed loop transmission diversity scheme in order to disseminate information toward almost static and battery-limited devices typically unable to communicate over long distances. We present results that show the multiplexing gain that is possible to get in UAV scenarios, which are characterized by the presence of a strong Line-of-Sight (LOS) component. Moreover, we show that in presence of a large amount of users or devices, data separation can be significantly improved by the use of low complexity blind receivers.
2017 XVII Workshop on Information Processing and Control (RPIC), 2017
The vision of a software defined radio (SDR) is to implement in different software systems of com... more The vision of a software defined radio (SDR) is to implement in different software systems of communications using the same hardware platform. An advanced SDR system consists of two fundamental components: a programmable RF component and another reconfigurable FPGA-based component in charge of performing high-speed signal processing. Since the sampling rate of the ADC and DAC converters is generally fixed and well above the rates required for the baseband processing of different communications systems, the SDRs employ programmable modules that perform the real-time processing rate changes. This article describes in detail the design and implementation in FPGA of a programmable CIC interpolator filter. By selecting the number of steps, the rate change and the delay factor, the frequency rejection is also configured, which could generate intermodulation problems in the RF step. It also describes the validation test and the analysis of resources used in FPGA.
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Papers by Graciela Corral-Briones