Amaia Arrinda

Digital terrestrial television (COFDM 8K system) field trials and coverage measurements in Spain

This article presents the results of the first digital terrestrial television field trials and coverage measurements in Spain. First of all the VIDITER project is presented. The main objective of this work is to study the behavior of a whole digital terrestrial television network, from source coding up to the final signal reception. At this point, the experimental network installed in Madrid is described. Next, the measurement campaign is explained, first, by describing the network configuration used for these first field trials, and then, paying attention to the criteria used to select the measurement points and the parameter set to be tested. Some of the results obtained are shown as a first approach to the figures needed to develop and plan a fully operational digital terrestrial television service.

Medium Wave Digital Radio Mondiale (DRM) Field Strength Time Variation in Different Reception Environments

This paper examines the temporal variability in fixed reception of the ground-wave propagated DRM (Digital Radio Mondiale) signal. This field strength analysis in the medium wave band has been performed using the first Spanish DRM field trial. Several fixed reception points located along radial routes provided the field strength sample distributions in rural and suburban areas. Additionally a second measurement campaign was carried out in several dense and open areas of downtown Madrid. The maximum likelihood estimations and logarithmic functions were used to analyse the fit of the experimental data with theoretical statistical distributions. A deep analysis of the most important parameters of the distribution has been carried out in order to characterize the field strength behavior in the different reception situations. It has been taken into account the influence of environment, measurement time interval, distance to the transmitter and the presence of critical reception impairments. The most remarkable result of this study has shown that the time variability of the ground-wave medium wave DRM channel is well approximated by a Log Normal and also by a Nakagami process. The Log Normal distribution is preferred as it is the one considered by the analog medium wave broadcasts for the ground-wave propagation case

DTV (COFDM) SFN signal variation field tests in urban environments for portable outdoor reception

The paper presents the measurement results obtained in an extensive field test campaign developed in two large cities of Spain (Madrid and Bilbao) with the aim of characterizing the portable outdoor reception of digital terrestrial television (COFDM - coded orthogonal frequency division multiplexed) and continue the studies carried out by the authors during the past years.

Field measurement based characterization of the wideband urban multipath channel for portable DTV reception in single frequency networks

This paper presents a study developed to obtain several parameters of the small scale fading of the wideband propagation channel applied to the portable and mobile reception of Digital Terrestrial Television (DTV) services in an urban Single Frequency Network (SFN) environment. The study is focused on the calculation of some relevant parameter values related to the multipath behavior of the channel, using field data collected in a real network. Mean values for the Root mean square Delay Spread (RDS) and the frequency domain Level Crossing Rate (LCR) are given, together with an analysis of the influence of the specific environment and network (SFN) features.

Optimization of the Coverage Area for DVB-T Single Frequency Networks Using a Particle Swarm Based Method

Single frequency networks (SFN) are usually considered to deploy OFDM modulation based digital broadcast systems, exploiting the multipath tolerance of the OFDM receivers, which are capable of combining signals coming from several transmitters with different propagation delays. In this work, a planning tool is proposed to improve the coverage area in SFN networks, optimizing transmission parameters such as the transmitters delay or power, using 3D digital terrain maps along with a propagation prediction tool to estimate the power received at each location inside the coverage area. A heuristic particle swarm optimization algorithm is used (PSO) to optimize transmission parameters. The approach proposed makes it possible to consider several configurations regarding both transmitters and receivers. Preliminary test results are shown for a SFN with eighteen transmitters and omnidirectional radiators at both sides that demonstrate the usefulness of the approach. Furthermore, results considering receivers with directive antennas as well as transmitters with sectored antennas are also included and discussed.

External Noise Measurements in the Medium Wave Band

This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems

MIMO Performance of the Next Generation DVB-T

This paper analyses the performance of a DTT (digital terrestrial television) broadcasting system that includes MIMO-OFDM techniques. The benefits of these techniques are studied comparing the results for different MIMO 2 x 2 (multiple input multiple output), MISO 2 x 1 (multiple input single output) and SISO (single input single output) system configurations. Different propagation channel models and configurations are considered for each diversity scheme. This study has been carried out in the context of development of the next generation DVB-T, called DVB-T2.

Digital-Radio-Mondiale (DRM) Measurement-System Design and Measurement Methodology for Fixed and Mobile Reception

This paper presents measurement-system design and measurement techniques developed to study digital-radio-mondiale signal behavior and system performance. The solution proposed considers different reception conditions and environments. Some aspects, like antenna selection and both internal and external noise measurements, have turned out to be key factors and are also presented.

SFN-SISO and SFN-MISO Gain Performance Analysis for DVB-T2 Network Planning

In DVB-T2, the single frequency network (SFN) mode is an attractive planning alternative to the well-known multiple frequency network (MFN) mode. SFN networks provide augmented spectrum efficiency as well as a quality of service improvement due to a more homogeneous distribution of the received signal strength over the coverage area. Nevertheless, some areas will also show degradation in practice. In order to improve the performance of the SFN operation, the second generation broadcast system DVB-T2 standard incorporates multiple input single output (MISO) antenna diversity mechanisms. Based on empirical analyses and system level simulations, this paper analyzes the key factors affecting the SFN operation. This paper analyzes SFN effects as well as the corresponding MISO gain margins for commercial and custom software defined radio (SDR) receiver implementations. The results show that the MISO gain is restricted only to the overlapping areas of an SFN where a small power imbalance between MISO groups, is present being the achievable MISO gain higher with high modulation code rates. The results also address that degradation arises in the non-overlapping regions of an SFN. This paper provides also updated C/N thresholds for DVB-T2 network planning.

DVB-T2 performance in presence of multipath laboratory tests

This paper presents the results of laboratory tests carried out to study the performance of DVB-T2 in presence of multipath in fixed reception with rooftop antenna. The typical multipath cause in this scenario is a Single Frequency Network (SFN) reception. A range of relative levels and delays between the main path and one echo are tested to obtain the C/N requirements for each case. DVB-T2 supports a large number of options that can be chosen to optimize the system. Some of those options (Pilot Patterns, Guard Interval Fraction, Rotated Constellations, FFT sizes) are tested to evaluate their performance. The results are compared with the simulation results available in the implementation guidelines for the extreme cases of Gaussian channel (no echo) and 0 dB echo channel (main path and echo at same level).