Poly-Harmonic Distortion Model Extraction in Charge-Controlled One-Port Devices

A charge-controlled, one-port device is used to describe and discuss the extraction procedure of a Poly-Harmonic Distortion (PHD) model in detail. For this case, both voltage and current waveforms are shown to be enough to fully characterize the PHD model. It is also shown that all the information specifically required for this PHD model definition can be stored in the Fourier coefficients of the incremental conductance and capacitance. The results are validated by comparing them with those obtained using a commercial circuit simulation tool.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Caracterización no-lineal de dispositivos de un puerto basada en el principio de distorsión poli-armónica

In this contribution the computation of a nonlinear diode model based on the Poly-Harmonic Distortion principle is described. The diode is composed of a non-linear conductance shunt connected to a non-linear capacitance, both of them quasistatic. The procedure used to extract these parameters only requires port-voltage and -current waveforms. The computed parameters of the model at different frequencies and power levels are presented and have been validated by comparing them with those obtained using a commercial circuit simulation tool (specifically with X-parameters). Unlike commercial CAD tools or conventional measurement set-ups the proposed technique can easily provide all the sensitivities related to DC components.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Adaptive SOVA for 3GPP-LTE Receivers

Turbo codes are extensively used in wireless communication systems and have been adopted as the channel coding scheme for next generation cellular standards. The complexity associated with the decoding process is an important issue. In this paper, we propose an adaptive Soft Output Viterbi Algorithm (adSOVA) based turbo decoder which is proved to reduce complexity without experiencing a degradation in error correction performance. The proposed adSOVA is evaluated in a long term evolution (LTE) downlink scenario and compared with the SOVA and the Max-Log-MAP algorithms. Simulation results show that a complexity reduction of 40% can be achieved with respect to the conventional SOVA with no BLock Error Rate (BLER) degradatio

Inversión aproximada de matrices en sistemas Massive MIMO correlados en tiempo o frecuencia

Massive multiple-input multiple-output (MIMO) is expected to be one of the keys in 5G. In this technology, the base station is equipped with a big number of antennas serving multiple users simultaneously to improve spectral efficiency, coverage, and range. Zero-Forcing and Minimum Mean Square Error have been considered potential practical precoding and detection methods for large scale MIMO systems but require much larger dimensions of matrix inversion. This paper presents an architecture for approximate matrix inversion based on Neumann Series, thereby reducing the cost of hardware. In addition, we propose a solution for systems with time or frequency correlation among different channels where we are able to reach a much higher throughput.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Further Improvements in SOVA for High-Throughput Parallel Turbo Decoding.

In this letter, we present two mechanisms based on soft-output Viterbi algorithm (SOVA) technique that achieve a performance close to maximum a-posteriori (MAP) decoding. First, we propose a new technique called alternating direction SOVA, which allows for improving the performance of SOVA in similar terms as bidirectional SOVA while barely affecting the area complexity. Then, we introduce the idea of parallel turbo decoding based on path metric/state border exchange. Unlike other techniques, overlapping between adjacent subblocks is not required, thus reducing the decoding latency dramatically. We evaluate their performance in the context of 3GPP-LTE, showing that the combination of both mechanisms achieves a BER performance close to parallel MAP decoding while having a lower complexit

Throughput-based quality adaptation for DASH in 5G mobile networks

Video streaming in mobile networks is currently the most widely used service and its usage is expected to grow exponentially in the next years. Due to the changing conditions of the radio interface, techniques likes Dynamic Adaptive Streaming over HTTP (DASH) allows the user equipment to request the video coding rate that better matches the instantaneous network capacity. There are three types of algorithms to select the appropriate video coding rate based on different types of quality of service metrics: throughput-based, buffer-based and hybrid. In this paper we present three different versions of a throughput-based algorithm, comparing their performance in terms of mean and mode of the video quality index as well as the number of overlapping video chunks. We focus on the end-user quality of experience to evaluate which is the implementation that optimizes the performance.Universidad de Málaga, Plan Nacional I+D (Ministerio de Economía y Competitividad) bajo el proyecto TEC2016-80090-C2-1-R. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

WM-SIMA: Herramienta de simulación para el enlace descendente LTE-Advanced

In this paper, we present a novel and efficient link level simulation framework for the donwlink (DL) of Long Term Evolution Advanced (LTE-A) cellular networks. The tool, called Wireless Mobile SIMulator Advanced (WM-SIMA), is available to be downloaded so that researchers can use it to evaluate the performance for different network configurations. In this work, the main characteristics of WM-SIMA are presented. As a case of use, the Average Spectral Efficiency (ASE) is obtained for the DL of a two-tier network, composed of Macro Access Points (MAPs) and Pico APs (PAPs). Simulation results confirms that there exist an optimal Cell Range Expansion (CRE) bias in the cell association that maximizes the ASE. Interestingly, it is confirmed that this optimal bias does not depend on the number of PAPs, while increasing the number of PAPs leads to a higher ASE for the same bias.Ministerio de Economía y Competitividad (TEC2013-44442-P). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Link abstraction models for multicarrier systems: A logistic regression approach

Evaluation of complex wireless systems through simulations is commonly tackled with an abstraction of physical link behavior. This procedure is performed in 2 phases: Firstly, training is performed at the link level, resulting in a mapping function from signal-to-interference-plus-noise ratio (SINR) to block error rate (BLER); and secondly, physical layer signal processing is replaced by the resulting link-level mapping function. Several methods have been proposed in the literature for link abstraction. The well-known exponential effective SINR mapping (EESM) is likely to be the most extensively used procedure for multicarrier transmission. In short, EESM estimates an effective SINR from the whole set of SINRs of useful subcarriers by means of a single parameter mapping function, which must be previously optimized through training. Later on, BLER is assumed as that of the effective SINR over an additive white Gaussian noise channel. In this paper, we propose a novel method for BLER prediction named as logistic regression-based link method (LRLM). Mean and standard deviation of the SINR set can accurately capture BLER behavior for wideband multicarrier systems through a simpler function, thus reducing the amount of information to be stored compared to EESM. Moreover, LRLM is very flexible and may include extra predictors to reduce the number of different models to be stored. Performance results show that LRLM is able to predict accurately the BLER for all modulation and coding schemes and transport block sizes defined for Long-Term Evolution technolog

Adaptación de enlace en comunicaciones móviles

Se describen las diferentes técnicas de adaptación de enlace empleadas principalmente en los sistemas de comunicaciones móviles. Modulación y codificación adaptativas (AMC). Prestaciones y comparación con sistemas sin adaptación Adaptación del esquema MIMO. Retrasmisión híbrida (H-ARQ). Corresponde al Tema 6 de la asignatura "Técnicas de tratamiento de señal y comunicaciones" del Máster en Ingeniería de Telecomunicación

Transmisión en canales con desvanecimientos

Se describen las características de los canales de comunicaciones inalámbricas y las técnicas de transmisión digital adecuadas para ellos. Modelo de canal inalámbrico sin visión directa de banda estrecha Rayleigh. Prestaciones de las técnicas clásicas sobre el canal Rayleigh. Transmisión en bloques entrelazados y sus prestaciones. Técnicas de diversidad espacial en recepción y transmisión. Multiplexación espacial (MIMO). Corresponde al Tema 5 de la asignatura "Técnicas de tratamiento de señal y comunicaciones" del Máster en Ingeniería de Telecomunicació