EXIT chart analysis of iteratively detected and SVD-assisted broadband MIMO-BICM schemes

In this contribution the number of activated MIMO layers and the number of bits per symbol are jointly optimized under the constraint of a given fixed data throughput and integrity. In general, non-frequency selective MIMO links have attracted a lot of research and have reached a state of maturity. By contrast, frequency selective MIMO links require substantial further research, where spatio-temporal vector coding (STVC) introduced by Raleigh seems to be an appropriate candidate for broadband transmission channels. In analogy to bit-interleaved coded irregular modulation, a broadband MIMO-BICM scheme is introduced, where different signal constellations and mappings are used within a single codeword. Extrinsic Information Transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. Our results show that in order to achieve the best bit-error rate, not necessarily all MIMO layers have to be activated

Modulation-mode assignment for SVD-assisted and iteratively detected downlink multiuser MIMO transmission schemes

In this contribution we jointly optimize the number of multiple-input multiple-output (MIMO) layers and the number of bits per symbol within an iteratively-detected multiuser MIMO downlink (DL) transmission scheme under the constraint of a given fixed data throughput and integrity. Instead of treating all the users jointly as in zero-forcing (ZF) multiuser transmission techniques, the investigated singular value decomposition (SVD) assisted DL multiuser MIMO system takes the individual user's channel characteristics into account. In analogy to bit-interleaved coded irregular modulation, we introduce a MIMO-BICM scheme, where different user-specific signal constellations and mapping arrangement were used within a single codeword. Extrinsic information transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. Our results show that in order to achieve the best bit-error rate, not necessarily all user-specific MIMO layers have to be activate

Modulation-mode and power-assignment for SVD-assisted downlink multiuser MIMO systems

Multiuser multiple-input multiple-output (MIMO) downlink (DL) transmission schemes experience both multiuser interference as well as inter-antenna interference. However, instead of treating all the users jointly as in zero-forcing (ZF) multiuser transmission techniques, the investigated singular value decomposition (SVD) assisted DL multiuser MIMO system takes the individual user's channel characteristics into account. The performed joint optimization of the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers has to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput

Performance Analysis of SVD-assisted Downlink Multiuser MIMO Systems

Multiuser multiple-input multiple-output (MIMO) downlink (DL) transmission schemes experience both multiuser interference as well as inter-antenna interference. Instead of treating all the users jointly as in zero-forcing (ZF) multiuser transmission techniques, the investigated singular value decomposition (SVD) assisted DL multiuser MIMO system takes the individual user’s channel characteristics into account. This translates to a choice of modulation constellation and transmitter power and, in our proposed system, to a choice of number of activated user-specific MIMO layers. The performed joint optimization of the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers has to be activated in both frequency-selective and non-frequency selective MIMO channels in order to minimize the overall BER under the constraint of a given fixed data throughput

Modulation-mode and power-assignment for SVD-and GMD-assisted downlink MIMO systems

Multiuser multiple-input multiple-output (MIMO) downlink (DL) transmission schemes experience both multiuser interference (MUI) as well as inter-antenna interference. However, instead of treating all the users jointly as in zero-forcing (ZF) multiuser transmission techniques, the investigated singular value decomposition (SVD) and geometric mean decomposition (GMD) assisted DL multiuser MIMO systems take the individual user's channel characteristics into account. The performed joint optimization of the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers have to be activated in order to minimize the overall BER under the constraint of a fixed data throughpu

Nuevas implementaciones digitales de sincronismos de BIT y portadora en Módem CPM

Las técnicas digitales aplicadas a receptores y transmisores están imponiéndose a las convencionales técnicas analógicas por las diversas ventajas que supone. En este sentido se impone una investigación con el fin de desarrollar dichas técnicas o mejorarlas en algún aspecto. La idea principal que engloba esta Tesis Doctoral es precisamente la indagación en algunas de dichas técnicas, su análisis, caracterización y aplicación a dos casos concretos. En un primer momento se han caracterizado dos canales de comunicaciones donde se pretende hacer uso de las técnicas a desarrollar. Este es un aspecto importante para conocer las condiciones reales en que deberán operar los algoritmos y cómo pueden verse afectados. Los canales que se caracterizan corresponden al establecido para satélites de órbita baja y el formado por las líneas de distribución de media tensión. En segundo lugar se ha realizado una descripción del tipo de modulación que se pretende emplear en los canales (GMSK) y se ha tratado de obtener una estructura del receptor con la menor complejidad posible. Basándose en una descripción de la modulación mediante una aproximación que da lugar a un modelo lineal, se desarrolla un receptor lineal de estructura sencilla y con unas prestaciones razonables, suponiendo una gran ventaja. Una vez descrita la estructura del receptor en el cual se van a emplear los algoritmos, se tratan dos aspectos cruciales en los receptores: la sincronización de portadora y el sincronismo de bit. Las técnicas que se desarrollan parten de la idea de su integración en un receptor totalmente digital. Son técnicas de procesado digital de señales. Se aborda el problema de la sincronización de portadora dando como solución diversos algoritmos que operan basándose en diferentes principios y obtienen diferentes características. Se destacan las ventajas e inconvenientes de cada uno de ellos y se presentan resultados de su funcionamiento. Respecto a la sincronización de bit se aborda el caso del empleo de interpoladores basados en la interpolación matemática para tal fin. Se trata de una técnica de cambio de velocidad de muestreo de forma dinámica para que las muestras de salida estén situadas en los instantes de muestreo óptimos. El interpolador lleva asociados un detector de error de sincronismo de bit y un sistema de control del interpolador. En el caso del detector de error se ha partido de la premisa de obtener un detector sencillo, de baja carga computacional y eficiente. El algoritmo se ha basado en el cruce por cero de la señal en las alternancias

Modulation-mode assignment in SVD-assisted multiuser MIMO-OFDM systems

In order to comply with the demand on increasing available data rates in particular in wireless technologies, systems with multiple transmit and receive antennas, also called MIMO (multiple-input multiple-output) systems, have become indispensable for future generations of wireless systems. Due to the strongly increasing demand in high-data rate transmission systems, frequency non-selective MIMO links have reached a state of maturity and frequency selective MIMO links are in the focus of interest. In this field, the combination of MIMO transmission and OFDM (orthogonal frequency division multiplexing) can be considered as an essential part of fulfilling the requirements of future generations of wireless systems. However, single-user scenarios have reached a state of maturity. By contrast multiple users’ scenarios require substantial further research, where in comparison to ZF (zero-forcing) multiuser transmission techniques, the individual user’s channel characteristics are taken into consideration in this contribution. The performed joint optimization of the number of activated MIMO layers and the number of transmitted bits per subcarrier along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers per subcarrier have to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput

Advances in technologies and techniques for ambient intelligence

Human activity attracting a lot of research activity in several fields including the use of wireless sensors, positioning technologies and techniques, embedded computing, remote sensing and energy management among others. There are a number of applications where the results of those investigations can be applied, including ambient intelligence to support human activity, particularly the elderly and disabled people. Ambient intelligence is a new paradigm for the information and communications technologies where the electronic/digital environment takes care of the people presence and their needs, becoming an active, adaptive and responsive environment

Resource allocation in GMD and SVD-based MIMO System

Singular-value decomposition (SVD)-based multiple-input multiple output (MIMO) systems, where the whole MIMO channel is decomposed into a number of unequally weighted single-input single-output (SISO) channels, have attracted a lot of attention in the wireless community. The unequal weighting of the SISO channels has led to intensive research on bit- and power allocation even in MIMO channel situation with poor scattering conditions identified as the antennas correlation effect. In this situation, the unequal weighting of the SISO channels becomes even much stronger. In comparison to the SVD-assisted MIMO transmission, geometric mean decomposition (GMD)-based MIMO systems are able to compensate the drawback of weighted SISO channels when using SVD, where the decomposition result is nearly independent of the antennas correlation effect. The remaining interferences after the GMD-based signal processing can be easily removed by using dirty paper precoding as demonstrated in this work. Our results show that GMD-based MIMO transmission has the potential to significantly simplify the bit and power loading processes and outperforms the SVD-based MIMO transmission as long as the same QAM-constellation size is used on all equally-weighted SISO channels

Modulation-mode Assignment for SVD-assisted Multiuser MIMO Systems with Correlation.

Multiuser multiple-input multiple-output (MIMO) downlink (DL) transmission schemes experience both multiuser interference as well as inter-antenna interference. The singular value decomposition provides an appropriate mean to process channel information and allows us to take the individual user’s channel characteristics into account rather than treating all users channels jointly as in zero-forcing (ZF) multiuser transmission techniques. However, uncorrelated MIMO channels has attracted a lot of attention and reached a state of maturity. By contrast, the performance analysis in the presence of antenna fading correlation, which decreases the channel capacity, requires substantial further research. The joint optimization of the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers has to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput