A novel channel estimation based on spread pilots for terrestrial digital video broadcasting

International audienceIn this paper, we propose a novel channel estimation technique based on spread pilots for digital video broadcasting. This technique consists in adding a linear preceding function before the OFDM modulation and dedicating one of the preceding sequence to transmit the pilot symbols for the channel estimation. The merits of this technique are its simplicity, its flexibility, and the gains in terms of spectral efficiency and useful bit rate obtained compared to the classical pilot based estimation schemes used in DVB standards. The performance evaluated over realistic channel models, shows the efficiency of this technique which turns out to be a promising channel estimation technique for the future terrestrial video broadcasting systems

2D Linear Precoded OFDM for future mobile Digital Video Broadcasting

International audienceIn this paper, we propose a novel channel estimation technique based on 2D spread pilots. The merits of this technique are its simplicity, its flexibility regarding the transmission scenarios, and the spectral efficiency gain obtained compared to the classical pilot based estimation schemes used in DVB standards. We derive the analytical expression of the mean square error of the estimator and show it is a function of the autocorrelation of the channel in both time and frequency domains. The performance evaluated over a realistic channel model shows the efficiency of this technique which turns out to be a promising channel estimation for the future mobile video broadcasting systems

Efficient MIMO-OFDM Schemes for Future Terrestrial Digital TV with Unequal Received Powers

International audienceThis article investigates the effect of equal and unequal received powers on the performances of different MIMO-OFDM schemes for terrestrial digital TV. More precisely, we focus on three types of non-orthogonal schemes: the BLAST scheme, the Linear Dispersion (LD) code and the Golden code, and we compare their performances to that of Alamouti scheme. Using two receiving antennas, we show that for moderate attenuation on the second antenna and high spectral efficiency, Golden code outperforms other schemes. However, Alamouti scheme presents the best performance for low spectral efficiency and equal received powers or when one antenna is dramatically damaged. When three antennas are used, we show that Golden code offers the highest robustness to power unbalance at the receiving sid

Efficient 3D Space Time Space Block Code for Future Terrestrial Digital TV

International audienceThis article introduces a 3D space-time-space block code for future terrestrial digital TV in single frequency networks. The proposed 3D code is based on a double layer structure designed for inter-cell and intra-cell space time coded transmissions. We show that this new structure is particularly efficient for SFN environments regardless of the location of the receiver. It is then suitable for fixed, portable and mobile receptions

Optimisation de systèmes de télévision numérique terrestre : Estimation de canal, Synchronisation et Schémas multi-antennes distribués

The first digital terrestrial TV system developed in Europe is DVB-T standard. OFDM modulation has been adopted by this standard. Some receiver algorithms associated to DVB-T system are based on pilot subcarriers which carry symbols known in advance by the receivers. In our study, we propose to spread each pilot symbols over several subcarriers using a precoding function. Hence, we develop a channel estimation method based on these pilots. Besides, an extension of this algorithm to space dimension is proposed. In a second part, carrier frequency offset and sampling frequency offset estimation algorithms processed before and after deprecoding function are developed. The last part focuses on the optimization of multiple antennas (MIMO) schemes in a single frequency network context. We introduce a 3D MIMO scheme which results from the combination of two different MIMO codes. An analysis on the choice of the codes constituting the 3D MIMO scheme distributed on two and three transmitters.Le premier système de TV numérique utilisant la modulation OFDM à avoir été standardisé est le système DVB-T. Ses algorithmes d'estimation de canal et de synchronisation fréquentielle sont basés sur l'exploitation de symboles pilotes qui sont connus à l'avance par les récepteurs et sont transmis sur certaines sous-porteuses. Dans notre étude, nous proposons d'étaler chaque symbole pilote sur plusieurs sous-porteuses. De nouveaux algorithmes de réception basés sur ces pilotes étalés sont développés et analysés. Aussi, un nouveau schéma MIMO appelé Space Code Block Code est proposé pour l'estimation de canal. La dernière partie de cette thèse est consacrée à l'optimisation de schémas MIMO dans un réseau mono-fréquence (SFN). Un nouveau schéma MIMO appelé Space Time Space Block Code ou MIMO 3D est proposé. Une analyse sur le choix des différents codes constituant le schéma MIMO 3D est effectuée pour un réseau SFN avec deux sites puis trois sites d'émission

A Correlation Model for Nonstationary Time-Variant On-Body Channels

The temporal variation of spatial correlation between on-body radio links is empirically characterized for different walking scenarios. Nonstationary behaviors are highlighted, and a model is proposed for the long-term fading correlation

Efficient Spread Pilot based Synchronization Method for Linear Precoded OFDM Systems

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