Search results for "Channel estimation"
showing 7 items of 7 documents
MUSIC-based modal channel estimation for wideband OFDM-OQAM
2008
Orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM) over wideband frequency selective multipath channels suffers from inter-symbol interference (ISI) and inter-carrier interference (ICI) that degrade its performance. Channel estimation and equalization are needed to combat these interferences. In this paper a novel channel estimator for passband OFDM-OQAM signaling over wideband multipath channels, which is based on multiple signal classification (MUSIC) with the Spatial Smoothing technique is presented. Numerical simulation results are presented in the low number of subcarriers, i.e. wideband, scenario.
Communication cost of channel estimation interpolation for group-based vehicular communications in cellular networks
2020
Las comunicaciones inalámbricas para aplicaciones vehiculares en sistemas celulares de quinta generación (5G) deben ser de baja latencia y alta fiabilidad. Entre otros factores, la cantidad de información de control que debe intercambiarse entre cada vehículo y la estación base puede penalizar la latencia de la comunicación. Varios casos de uso vehicular 5G implican comunicaciones dentro de grupos de vehículos, por ejemplo el pelotón de vehículos. Este trabajo se centra en explotar la estructura y características de este servicio vehicular particular basado en grupos para disminuir el intercambio de información de control relacionado con la etapa de estimación del canal necesaria para las c…
A Channel-Aware Adaptive System for Underwater Acoustic Communications
2021
In recent years, underwater communications have seen a growing interest pushed by marine research, oceanography, marine commercial operations, offshore oil industry and defense applications. Generally, underwater communications employ audio signals which can propagate relatively far. However, acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solution…
A Channel-Aware Adaptive Modem for Underwater Acoustic Communications
2021
Acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solutions. Indeed, the design of environment-specific solutions is especially critical for modulations with high spectral efficiency, which are very sensitive to channel characteristics. In this paper, we design and implement a software-defined modem able to dynamically estimate the acoustic channel c…
A simple joint estimation-detection technique for OFDM systems
2005
In this work a simple approach for the joint estimation-detection in a frequency selective severe fading environment of OFDM signals adopting PSK constellations is presented. A linear predictor of suitable order is adopted for the channel estimation in the frequency domain. The predictor coefficients are estimated on the basis of a sample estimation of the autocorrelation of the channel frequency response, aided by a preliminary differential decoding, in a blockwise manner. The detection technique proposed here is based on a simple tree search where a small number of best survivor paths are maintained at each step. Despite the simplicity of above detection approach, the simulation results s…
A Kalman Filter Approach for Distinguishing Channel and Collision Errors in IEEE 802.11 Networks
2008
In the last years, several strategies for maximizing the throughput performance of IEEE 802.11 networks have been proposed in literature. Specifically, it has been shown that optimizations are possible both at the medium access control (MAC) layer, and at the physical (PHY) layer. In fact, at the MAC layer, it is possible to minimize the channel waste due to collisions and backoff expiration times, by tuning the minimum contention window as a function of the network congestion level. At the PHY layer, it is possible to improve the transmission robustness, by selecting a suitable modulation/coding scheme as a function of the channel quality perceived by the stations. However, the feasibility…
Low-complexity AoA and AoD estimation in the transformed spatial domain for millimeter wave MIMO channels
2021
La estimación del ángulo de llegada (AoA) y del ángulo de salida (AoD) es fundamental para la búsqueda de celdas, las comunicaciones estables y el posicionamiento en los sistemas celulares de ondas milimétricas (mmWave). Además, el diseño de algoritmos de estimación de AoA/AoD de baja complejidad resulta también de gran importancia en el despliegue de sistemas prácticos para permitir un cálculo rápido y eficiente de la conformación de haz. La estimación paramétrica del canal en ondas milimétricas permite describir la matriz del canal como una combinación de trayectorias de señales dependientes de la dirección, explotando la característica de dispersión de los canales mmWave. En este context…