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James L Garrison - One of the best experts on this subject based on the ideXlab platform.

  • remote sensing of snow water equivalent using coherent reflection from Satellite signals of opportunity theoretical modeling
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2017
    Co-Authors: Simon Yueh, Rashmi Shah, James L Garrison, Yunjin Kim, Abi Komanduru, Kelly Elder
    Abstract:

    A model for the remote sensing of snow water equivalent (SWE) using coherent detection of reflected Communication Satellite “signals of opportunity” is described in this paper. We modeled the snowpack by a layered medium and compute the phase of specularly reflected signals from the snowpack. Phase change of the reflected signal is predicted to be strongly dependent on SWE for dry snow and on snow depth for wet snow. Phase sensitivity to SWE increases with frequency. Reflected signals with frequencies above S-band, however, will experience rapid phase wrapping (360° change) and become more susceptible to fringe washing due to spatial variability of SWE across the footprint. We also examined the impact of snow grain size, snow density, snow layering, ground surface scattering, and incoherent scattering from ice grains embedded in the snowpack, concluding that these factors do not have a substantial impact on the phase-SWE relationship. However, the snow wetness of more than a few percent can make the reflection from air–snow interface dominant, leading to a correlation between phase change and snow depth. To address the path delay due to the ionosphere, dual-frequency observations would have to be considered. Modeling analysis indicates that the coherent change detection is a promising technique for remote sensing of SWE.

  • recent results on soil moisture remote sensing using p band signals of opportunity
    International Conference on Electromagnetics in Advanced Applications, 2017
    Co-Authors: James L Garrison, B Nold, Jeffrey R Piepmeier, Manuel Vega, Matthew Fritts, Yc Lin, Garett Pignotti, C Dutoit, Joseph Knuble
    Abstract:

    Root zone soil moisture (RZSM) is an essential variable in meteorology, hydrology, and agriculture. Current methods in passive and active microwave remote sensing at L-band (e.g. SMOS or SMAP) are limited to a sensing depth of less than 10 cm. Observing RZSM (water in the top meter of soil) will require lower frequencies (P-band), presenting significant difficulties for a spaceborne instrument, due to the required antenna size, the presence of radio-frequency interference (RFI), and competition for spectrum allocations (in the case of active radar). Bistatic radar using Signal of Opportunity (SoOp) (e.g. digital Satellite transmitters) offers the possibility of remote sensing using powerful signals already occupying bands allocated for Communications. This paper will present early results from the first airborne campaign to study P-band reflectometry for soil moisture, conducted in Oklahoma between October 17–26, 2016. A geosynchronous Communication Satellite, transmitting a 25 KHz data signal on a 260.375 MHz carrier was uses at the signal source. Preliminary assessment of the data showed high reflectivity over a lake and consistent results between subsequent overflights of the watershed. Recently, a tower experiment has started using a 20 MHz wide signal centered at 370 MHz. Linearly polarized measurements were made over bare soil between 25-May-2017 and 8-June-2017 observing a strong reflected signal. Corn is being planted on the field and measurements will be made throughout the growing season.

  • remote sensing of soil moisture using p band signals of opportunity soop initial results
    International Geoscience and Remote Sensing Symposium, 2017
    Co-Authors: James L Garrison, Yaocheng Lin, B Nold, Jeffrey R Piepmeier, Manuel Vega, Matthew Fritts, Cornelis Du Toit, Joseph Knuble
    Abstract:

    Initial results from the first airborne campaign to evaluate P-band reflectometry for soil moisture remote sensing are presented. P-band radiation has a penetration depth of 10–20 cm, compared to around 5 cm for L-band. This offers the possibility of measuring Root-Zone Soil Moisture (RZSM), a capability that does not presently exist in spaceborne remote sensing. Signals of Opportunity Airborne Demonstrator (SoOp-AD) is a brassboard P-band reflectometry demonstration instrument, developed under the NASA Instrument Incubator Program (IIP-13). Soil reflectivity is estimated from the cross-correlation of direct and reflected signals from a geostationary Communication Satellite. SoOp-AD will demonstrate key technological advancements on the roadmap to a spaceborne instrument, including an FPGA-based correlator array and “smart antenna” nullsteering in the post-processing stage. The first airborne tests of SoOp-AD were conducted around the ARS Micronet in Little Washita, OK. Initial results confirm the assumption of coherent scattering, show the water-land transition over Lake Ellsworth, and present reasonable values for reflectivity over the instrumented area.

  • application of the icf coherence time method for ocean remote sensing using digital Communication Satellite signals
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014
    Co-Authors: Rashmi Shah, James L Garrison
    Abstract:

    This paper applies an ocean remote sensing method, first developed for reflected Global Navigation Satellite System (GNSS-R) signals, to reflected digital Communication Satellite signals. The fundamental observation is the time series of the Interferometric Complex Field (ICF) of the reflected signal. A relationship is derived between the coherence time of the ICF time series and the significant wave height (SWH) and mean wave period (MWP) of the ocean. Direct and reflected signals from the S-band Satellite transmissions providing the commercial XM radio service were recorded at Platform Harvest over a 65-day period. In situ measurements from a nearby buoy were used to calibrate this measurement by determining coefficients of a semi-empirical model. SWH retrievals using this model on 1 min of reflected signal observations were found to have a standard deviation of 0.38 m over the range from 1 to 4.5 m. An error analysis was done to show that the primary contribution to this error was uncertainty in the relationship between MWP and SWH, and to quantify the retrieval error from different forward models.

  • demonstration of bistatic radar for ocean remote sensing using Communication Satellite signals
    IEEE Geoscience and Remote Sensing Letters, 2012
    Co-Authors: Rashmi Shah, James L Garrison, Michael S Grant
    Abstract:

    Remote sensing of ocean roughness using reflected signals from digital Communication Satellites is demonstrated in an airborne experiment. Transmitted data are approximated as an infinitely long sequence of random bits, which is experimentally a hypothesis confirmed for the S-band XM radio signal. On July 2, 2010, a signal recorder was flown at an altitude of 3.17 km off the coast of Virginia, collecting ocean-reflected signals from both geostationary Satellites identified as “Rhythm” and “Blues,” which were broadcasting the XM radio signal. Direct and reflected signals from the same channel were cross-correlated, producing a waveform that agreed well with a model generated at the 7.5-m/s wind speed reported from the Chesapeake Lighthouse. Adjusting this model to fit the experimental data produced an optimal estimate of 6 m/s. A Monte Carlo approach predicted errors of 0.5% from the simulated reflected XM radio signals and 2%-10% from simulated reflected Global Navigation Satellite System (GNSS-R) signals. This improvement was attributed to the higher ( ~ 30 dB) power in the XM radio signal. The availability of Communication Satellite transmissions, in all frequency bands used for remote sensing, opens the possibility of using signals of opportunity as low-cost alternatives to radiometry or scatterometry.

Rashmi Shah - One of the best experts on this subject based on the ideXlab platform.

  • remote sensing of snow water equivalent using coherent reflection from Satellite signals of opportunity theoretical modeling
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2017
    Co-Authors: Simon Yueh, Rashmi Shah, James L Garrison, Yunjin Kim, Abi Komanduru, Kelly Elder
    Abstract:

    A model for the remote sensing of snow water equivalent (SWE) using coherent detection of reflected Communication Satellite “signals of opportunity” is described in this paper. We modeled the snowpack by a layered medium and compute the phase of specularly reflected signals from the snowpack. Phase change of the reflected signal is predicted to be strongly dependent on SWE for dry snow and on snow depth for wet snow. Phase sensitivity to SWE increases with frequency. Reflected signals with frequencies above S-band, however, will experience rapid phase wrapping (360° change) and become more susceptible to fringe washing due to spatial variability of SWE across the footprint. We also examined the impact of snow grain size, snow density, snow layering, ground surface scattering, and incoherent scattering from ice grains embedded in the snowpack, concluding that these factors do not have a substantial impact on the phase-SWE relationship. However, the snow wetness of more than a few percent can make the reflection from air–snow interface dominant, leading to a correlation between phase change and snow depth. To address the path delay due to the ionosphere, dual-frequency observations would have to be considered. Modeling analysis indicates that the coherent change detection is a promising technique for remote sensing of SWE.

  • application of the icf coherence time method for ocean remote sensing using digital Communication Satellite signals
    IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014
    Co-Authors: Rashmi Shah, James L Garrison
    Abstract:

    This paper applies an ocean remote sensing method, first developed for reflected Global Navigation Satellite System (GNSS-R) signals, to reflected digital Communication Satellite signals. The fundamental observation is the time series of the Interferometric Complex Field (ICF) of the reflected signal. A relationship is derived between the coherence time of the ICF time series and the significant wave height (SWH) and mean wave period (MWP) of the ocean. Direct and reflected signals from the S-band Satellite transmissions providing the commercial XM radio service were recorded at Platform Harvest over a 65-day period. In situ measurements from a nearby buoy were used to calibrate this measurement by determining coefficients of a semi-empirical model. SWH retrievals using this model on 1 min of reflected signal observations were found to have a standard deviation of 0.38 m over the range from 1 to 4.5 m. An error analysis was done to show that the primary contribution to this error was uncertainty in the relationship between MWP and SWH, and to quantify the retrieval error from different forward models.

  • demonstration of bistatic radar for ocean remote sensing using Communication Satellite signals
    IEEE Geoscience and Remote Sensing Letters, 2012
    Co-Authors: Rashmi Shah, James L Garrison, Michael S Grant
    Abstract:

    Remote sensing of ocean roughness using reflected signals from digital Communication Satellites is demonstrated in an airborne experiment. Transmitted data are approximated as an infinitely long sequence of random bits, which is experimentally a hypothesis confirmed for the S-band XM radio signal. On July 2, 2010, a signal recorder was flown at an altitude of 3.17 km off the coast of Virginia, collecting ocean-reflected signals from both geostationary Satellites identified as “Rhythm” and “Blues,” which were broadcasting the XM radio signal. Direct and reflected signals from the same channel were cross-correlated, producing a waveform that agreed well with a model generated at the 7.5-m/s wind speed reported from the Chesapeake Lighthouse. Adjusting this model to fit the experimental data produced an optimal estimate of 6 m/s. A Monte Carlo approach predicted errors of 0.5% from the simulated reflected XM radio signals and 2%-10% from simulated reflected Global Navigation Satellite System (GNSS-R) signals. This improvement was attributed to the higher ( ~ 30 dB) power in the XM radio signal. The availability of Communication Satellite transmissions, in all frequency bands used for remote sensing, opens the possibility of using signals of opportunity as low-cost alternatives to radiometry or scatterometry.

Michael S Grant - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of bistatic radar for ocean remote sensing using Communication Satellite signals
    IEEE Geoscience and Remote Sensing Letters, 2012
    Co-Authors: Rashmi Shah, James L Garrison, Michael S Grant
    Abstract:

    Remote sensing of ocean roughness using reflected signals from digital Communication Satellites is demonstrated in an airborne experiment. Transmitted data are approximated as an infinitely long sequence of random bits, which is experimentally a hypothesis confirmed for the S-band XM radio signal. On July 2, 2010, a signal recorder was flown at an altitude of 3.17 km off the coast of Virginia, collecting ocean-reflected signals from both geostationary Satellites identified as “Rhythm” and “Blues,” which were broadcasting the XM radio signal. Direct and reflected signals from the same channel were cross-correlated, producing a waveform that agreed well with a model generated at the 7.5-m/s wind speed reported from the Chesapeake Lighthouse. Adjusting this model to fit the experimental data produced an optimal estimate of 6 m/s. A Monte Carlo approach predicted errors of 0.5% from the simulated reflected XM radio signals and 2%-10% from simulated reflected Global Navigation Satellite System (GNSS-R) signals. This improvement was attributed to the higher ( ~ 30 dB) power in the XM radio signal. The availability of Communication Satellite transmissions, in all frequency bands used for remote sensing, opens the possibility of using signals of opportunity as low-cost alternatives to radiometry or scatterometry.

James D Moore - One of the best experts on this subject based on the ideXlab platform.

  • fabrication and deployment testing of solar sail quadrants for a 20 meter solar sail ground test system demonstration
    41st AIAA ASME SAE ASEE Joint Propulsion Conference & Exhibit, 2005
    Co-Authors: Greg Laue, David Case, James D Moore
    Abstract:

    A 20-meter Scalable Square Solar Sail (S(sup 4)) System was produced and successfully completed functional vacuum testing in NASA Glenn's Space Power Facility at Plum Brook Station Ohio in May 2005. The S(sup 4) system was designed and developed by ATK Space Systems, and the design and production of the Solar Sails for this system was carried out by SRS Technologies. The S(sup 4) system consists of a central structure with four deployable carbon fiber masts that support four triangular sails. SRS has developed an effective and efficient design for triangular sail quadrants that are supported at three points and provide a flat reflective surface with a high fill factor. This sail design is robust enough for deployments in a one atmosphere, one gravity environment and incorporates several advanced features including adhesiveless seaming of membrane strips, compliant edge borders to allow for film membrane cord strain mismatch without causing wrinkling and low mass (3% of total sail mass) ripstop. This paper will outline some of the sail design and fabrication processes and the mature production, packaging and deployment processes that have been developed. This paper will also detail the successful ambient and vacuum testing of the sails and the ATK spacecraft structure. Based on recent experience and testing, SRS is confidant that high Technology Readiness Level (TRL) 5-6 solar sails in the 40-120-meter size range with areal density in the 4-5 grams per square meters (sail minus structure) range can be produced with existing technology. Additional film production research will lead to further reductions in film thickness to less than 1 micron enabling production of sails with areal densities as low as 2.0 grams per square meters using the current design, resulting in a system areal densities as low as 5.3 grams per square meters (sail and structure). These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community. The fundamental technologies required to produce these systems has been demonstrated on the 20-meter S(sup 4) sails that have recently completed ground testing demonstrating a mature and technology suitable for incorporation into future flight validation and future mission. Solar Sails can support NASA's Vision for Space Exploration by allowing Communication Satellite orbits that can maintain continuous Communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

  • fabrication end deployment testing of meter solar sail quadrants for a scaleable square solar sail ground test system
    46th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference, 2005
    Co-Authors: Greg Laue, David Case, James D Moore
    Abstract:

    2 . These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community and the fundamental technology required to produce these sails has been demonstrated on the ground test sails that have recently been built. These demonstrations have shown that the technology is maturing enough to enable solar sails to be built to support critical science missions. Solar Sails will support NASA's Vision for Space Exploration by allowing Communication Satellite orbits that can maintain continuous Communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

Rendón Morales Elizabeth - One of the best experts on this subject based on the ideXlab platform.

  • Contributions based on cross-layer design for quality-of-service provisioning over DVB-S2/RCS broadband Satellite system
    Universitat Politècnica de Catalunya, 2013
    Co-Authors: Rendón Morales Elizabeth
    Abstract:

    Contributions based on cross-layer design for Quality-of-Service provisioning over DVB-S2/RCS Broadband Satellite Systems Nowadays, geostationary (GEO) Satellite infrastructure plays a crucial role for the provisioning of IP services. Such infrastructure can provide ubiquity and broadband access, being feasible to reach disperse populations located worldwide within remote areas where terrestrial infrastructure can not be deployed. Nevertheless, due to the expansion of the World Wide Web (WWW), new IP applications such as Voice over IP (VoIP) and multimedia services requires considering different levels of individual packet treatment through the Satellite network. This differentiation must include not only the Quality of Service (QoS) parameters to specify packet transmission priorities across the network nodes, but also the required amount of bandwidth assignment to guarantee its transport. In this context, the provisioning of QoS guarantees over GEO Satellite systems becomes one of the main research areas of organizations such as the European Space Agency (ESA). Mainly because, their current infrastructures require continuous exploitation, as launching a new Communication Satellite is associated with excessive costs. Therefore, the support of IP services with QoS guarantees must be developed on the terrestrial segment to enable using the current assets. In this PhD thesis several contributions to improve the QoS provisioning over DVB-S2/RCS Broadband Satellite Systems have been developed. The contributions are based on cross-layer design, following the layered model standardized in the ETSI TR 102 157 and 462. The proposals take into account the drawbacks posed by GEO Satellite systems such as delay, losses and bandwidth variations. The first contribution proposes QoSatArt, an architecture defined to improve QoS provisioning among services classes considering the physical layer variations due to the presence of rain events. The design is developed inside the gateway, including the specification of the main functional blocks to provide QoS guarantees and mechanisms to minimize de delay and jitter values experienced at the application layer. Here, a cross-layer design between the physical and the network layer has been proposed, to enforce the QoS specifications based on the available bandwidth. The proposed QoSatArt architecture is evaluated using the NS-2 simulation tool. In addition, the performance analysis of several standard Transmission Control Protocol (TCP) variants is also performed. This is carry out to find the most suitable TCP variant that enhances TCP transmission over a QoS architecture such as the QoSatArt. The second contribution proposes XPLIT, an architecture developed to enhance TCP transmission with QoS for DVB-S2/RCS Satellite systems. Complementary to QoSatArt, XPLIT introduces Performance Enhanced Proxies (PEPs), which breaks the end-to-end semantic of TCP connections. However, it considers a cross-layer design between the network layer and the transport layer to enhance TCP transmission while providing them with QoS guarantees. Here, a modified TCP variant called XPLIT-TCP is proposed to send data through the forward and the return channel. XPLIT-TCP uses two control loops (the buffer occupancy and the service rate to provide optimized congestion control functions. The proposed XPLIT architecture is evaluated using the NS-2 simulation tool. Finally, the third contribution of this thesis consists on the development of a unified architecture to provide QoS guarantees based on cross-layer design over broadband Satellite systems. It adopts the enhancements proposed by the QoSatArt architecture working at the network layer, in combination with the enhancements proposed by the XPLIT architecture working at the transport layer.Actualmente, los satélites Geoestacionarios (GEO) juegan un papel muy importante en la provisión de servicios IP. Esta infraestructura permite proveer ubicuidad y acceso de banda ancha, haciendo posible alcanzar poblaciones dispersas en zonas remotas donde la infraestructura terrestre es inexistente. Sin embargo, en la provisión de aplicaciones como Voz sobre IP (VoIP) y servicios multimedia, es importante considerar el tratamiento diferenciado de paquetes a través de la red satelital. Esta diferenciación debe considerar no solo los requerimientos de Calidad de Servicio (QoS) que especifican las prioridades de los paquetes a través de los nodos de red, si no también el ancho de banda asignado para garantizar su transporte. En este contexto, la provisión de garantías de QoS sobre satélites GEO es una de las Principales áreas de investigación de organizaciones como la Agencia Espacial Europea (ESA) persiguen. Esto se debe principalmente ya que dichas organizaciones requieren la explotación continua de sus activos, dado que lanzar un nuevo satélite al espacio representa costos excesivos. Como resultado, el soporte de servicios IP con calidad de servicio sobre la infraestructura satelital actual es de vital importancia. En esta tesis doctoral se presentan varias contribuciones para el soporte a la Calidad de Servicio en redes DVB-S2/RCS satelitales de banda ancha. Las contribuciones propuestas se basan principalmente en el diseño ”cross-layer” siguiendo el modelo de capas definido y estandarizado en las especificaciones ETSI TR 102 157 [ETS03] y 462 [10205]. Las contribuciones propuestas consideran las limitaciones presentes de los sistemas satelitales GEO como lo son el retardo de propagación, la perdida de paquetes y las variaciones de ancho de banda causados por eventos atmosféricos. La primera contribución propone QoSatArt, una arquitectura definida para mejorar el soporte a la QoS. Esta arquitectura considera las variaciones en la capa física debido a la presencia de eventos de lluvia para priorizar los niveles de QoS. El diseño se desarrolla en el gateway e incluye las especificaciones de los principales elementos funcionales y mecanismos para garantizar la QoS y minimizar el retardo presente en la capa de aplicación. Aquí, se propone un diseño ”cross-layer” entre la capa física y la capa de red, con el objetivo de reforzar las especificaciones de QoS considerando el ancho de banda disponible. La arquitectura QoSatArt es simulada y evaluada empleando la herramienta de simulación NS-2. Adicionalmente, un análisis de desempeño de diversas variantes de TCP (Transmission Control Protocol) es realizado con el objetivo de encontrar la variante de TCP más adecuada para trabajar en un ambiente con QoS como QoSatArt. La segunda contribución propone XPLIT, una arquitectura desarrollada para mejorar las transmisiones TCP con QoS en un sistema satelital DVB-S2/RCS. Complementario a QoSatArt, XPLIT emplea PEPs (Performance Enhanced Proxies), afectando la semántica end-to-end de las conexiones TCP. Sin embargo, XPLIT considera un diseño ”cross-layer” entre la capa de red y la capa de transporte con el objetivo de mejorar las transmisiones TCP considerando los parámetros de QoS como la ocupación de la cola y la tasa de transmisión (_i, _i). Aquí, se propone el uso de una nueva variante de TCP es propuesta llamada XPLIT-TCP, que usa dos bucles para proveer funciones mejoradas en el control de congestión. La arquitectura XPLIT es simulada y evaluada empleando la herramienta de simulación NS-2. Finalmente, la tercera contribución de esta tesis consiste en el desarrollo de un arquitectura unificada para el soporte a la QoS en redes satelitales de banda ancha basada en técnicas ”cross-layer”. Esta arquitectura adopta las mejoras propuestas por QoSatArt en la capa de red en combinación con las mejoras propuestas por XPLIT en la capa de transporte.Postprint (published version

  • Contributions based on cross-layer design for quality-of-service provisioning over DVB-S2/RCS broadband Satellite system
    Universitat Politècnica de Catalunya, 2013
    Co-Authors: Rendón Morales Elizabeth
    Abstract:

    Contributions based on cross-layer design for Quality-of-Service provisioning over DVB-S2/RCS Broadband Satellite Systems Nowadays, geostationary (GEO) Satellite infrastructure plays a crucial role for the provisioning of IP services. Such infrastructure can provide ubiquity and broadband access, being feasible to reach disperse populations located worldwide within remote areas where terrestrial infrastructure can not be deployed. Nevertheless, due to the expansion of the World Wide Web (WWW), new IP applications such as Voice over IP (VoIP) and multimedia services requires considering different levels of individual packet treatment through the Satellite network. This differentiation must include not only the Quality of Service (QoS) parameters to specify packet transmission priorities across the network nodes, but also the required amount of bandwidth assignment to guarantee its transport. In this context, the provisioning of QoS guarantees over GEO Satellite systems becomes one of the main research areas of organizations such as the European Space Agency (ESA). Mainly because, their current infrastructures require continuous exploitation, as launching a new Communication Satellite is associated with excessive costs. Therefore, the support of IP services with QoS guarantees must be developed on the terrestrial segment to enable using the current assets. In this PhD thesis several contributions to improve the QoS provisioning over DVB-S2/RCS Broadband Satellite Systems have been developed. The contributions are based on cross-layer design, following the layered model standardized in the ETSI TR 102 157 and 462. The proposals take into account the drawbacks posed by GEO Satellite systems such as delay, losses and bandwidth variations. The first contribution proposes QoSatArt, an architecture defined to improve QoS provisioning among services classes considering the physical layer variations due to the presence of rain events. The design is developed inside the gateway, including the specification of the main functional blocks to provide QoS guarantees and mechanisms to minimize de delay and jitter values experienced at the application layer. Here, a cross-layer design between the physical and the network layer has been proposed, to enforce the QoS specifications based on the available bandwidth. The proposed QoSatArt architecture is evaluated using the NS-2 simulation tool. In addition, the performance analysis of several standard Transmission Control Protocol (TCP) variants is also performed. This is carry out to find the most suitable TCP variant that enhances TCP transmission over a QoS architecture such as the QoSatArt. The second contribution proposes XPLIT, an architecture developed to enhance TCP transmission with QoS for DVB-S2/RCS Satellite systems. Complementary to QoSatArt, XPLIT introduces Performance Enhanced Proxies (PEPs), which breaks the end-to-end semantic of TCP connections. However, it considers a cross-layer design between the network layer and the transport layer to enhance TCP transmission while providing them with QoS guarantees. Here, a modified TCP variant called XPLIT-TCP is proposed to send data through the forward and the return channel. XPLIT-TCP uses two control loops (the buffer occupancy and the service rate to provide optimized congestion control functions. The proposed XPLIT architecture is evaluated using the NS-2 simulation tool. Finally, the third contribution of this thesis consists on the development of a unified architecture to provide QoS guarantees based on cross-layer design over broadband Satellite systems. It adopts the enhancements proposed by the QoSatArt architecture working at the network layer, in combination with the enhancements proposed by the XPLIT architecture working at the transport layer.Actualmente, los satélites Geoestacionarios (GEO) juegan un papel muy importante en la provisión de servicios IP. Esta infraestructura permite proveer ubicuidad y acceso de banda ancha, haciendo posible alcanzar poblaciones dispersas en zonas remotas donde la infraestructura terrestre es inexistente. Sin embargo, en la provisión de aplicaciones como Voz sobre IP (VoIP) y servicios multimedia, es importante considerar el tratamiento diferenciado de paquetes a través de la red satelital. Esta diferenciación debe considerar no solo los requerimientos de Calidad de Servicio (QoS) que especifican las prioridades de los paquetes a través de los nodos de red, si no también el ancho de banda asignado para garantizar su transporte. En este contexto, la provisión de garantías de QoS sobre satélites GEO es una de las Principales áreas de investigación de organizaciones como la Agencia Espacial Europea (ESA) persiguen. Esto se debe principalmente ya que dichas organizaciones requieren la explotación continua de sus activos, dado que lanzar un nuevo satélite al espacio representa costos excesivos. Como resultado, el soporte de servicios IP con calidad de servicio sobre la infraestructura satelital actual es de vital importancia. En esta tesis doctoral se presentan varias contribuciones para el soporte a la Calidad de Servicio en redes DVB-S2/RCS satelitales de banda ancha. Las contribuciones propuestas se basan principalmente en el diseño ”cross-layer” siguiendo el modelo de capas definido y estandarizado en las especificaciones ETSI TR 102 157 [ETS03] y 462 [10205]. Las contribuciones propuestas consideran las limitaciones presentes de los sistemas satelitales GEO como lo son el retardo de propagación, la perdida de paquetes y las variaciones de ancho de banda causados por eventos atmosféricos. La primera contribución propone QoSatArt, una arquitectura definida para mejorar el soporte a la QoS. Esta arquitectura considera las variaciones en la capa física debido a la presencia de eventos de lluvia para priorizar los niveles de QoS. El diseño se desarrolla en el gateway e incluye las especificaciones de los principales elementos funcionales y mecanismos para garantizar la QoS y minimizar el retardo presente en la capa de aplicación. Aquí, se propone un diseño ”cross-layer” entre la capa física y la capa de red, con el objetivo de reforzar las especificaciones de QoS considerando el ancho de banda disponible. La arquitectura QoSatArt es simulada y evaluada empleando la herramienta de simulación NS-2. Adicionalmente, un análisis de desempeño de diversas variantes de TCP (Transmission Control Protocol) es realizado con el objetivo de encontrar la variante de TCP más adecuada para trabajar en un ambiente con QoS como QoSatArt. La segunda contribución propone XPLIT, una arquitectura desarrollada para mejorar las transmisiones TCP con QoS en un sistema satelital DVB-S2/RCS. Complementario a QoSatArt, XPLIT emplea PEPs (Performance Enhanced Proxies), afectando la semántica end-to-end de las conexiones TCP. Sin embargo, XPLIT considera un diseño ”cross-layer” entre la capa de red y la capa de transporte con el objetivo de mejorar las transmisiones TCP considerando los parámetros de QoS como la ocupación de la cola y la tasa de transmisión (_i, _i). Aquí, se propone el uso de una nueva variante de TCP es propuesta llamada XPLIT-TCP, que usa dos bucles para proveer funciones mejoradas en el control de congestión. La arquitectura XPLIT es simulada y evaluada empleando la herramienta de simulación NS-2. Finalmente, la tercera contribución de esta tesis consiste en el desarrollo de un arquitectura unificada para el soporte a la QoS en redes satelitales de banda ancha basada en técnicas ”cross-layer”. Esta arquitectura adopta las mejoras propuestas por QoSatArt en la capa de red en combinación con las mejoras propuestas por XPLIT en la capa de transporte