The Software Defined Radio for Wireless Systems

International audienceThe Software Defined Radio (SDR) paradigm aims at replacing most of analog functions of radio transceivers by digital processing blocks. This approach enables to tend to more flexible and reconfigurable terminals. But up to now, actual SDR systems are mostly applicable for basestations or access points, while it’s still problematic to implement small form factor solutions for mobile terminals.The INRIA Socrate team aims at addressing the challenges of SDR in practical devices, considering technical issues from the viewpoint of flexible radio front-ends, agile resource allocation and efficient programming of such devices.This presentation will focus on the main challenges of designing an SDR system depending on the application scenario and the kind of wireless standards available in the environment. These techniques, currently developed for classical long range wireless systems, could find some new constraints in the field of RFID, from the reader side for example

Analysis of a Spatial Modulation System over Time-varying Rician Fading Channel with a CSI Detector

International audienceSpatial Modulation (SM) is proposed in the literature as a new Multiple-Input Multiple-Output (MIMO) transmission scheme. The advantage of the SM consists in using only one RF (Radio Frequency) chain in the transmitting end which helps to increase the energy efficiency and the performance of the transmission. The related work in the literature is mostly based on the study of the SM transmission under the simple channel models. Moreover, it is assumed that the perfect Channel State Information (CSI) is known by the receiving end. This article discusses a CSI detector for the channel estimation and analyzes the performance of the proposed system over the time-varying Rician fading channel. The ADS-Matlab co-simulation results demonstrate that the bit error rate (BER) can be kept at an acceptable level with a realistic CSI detector, and in this case the system offers better performance with a small Rician factor

Full Duplex Spatial Modulation System Performance Depending on Self-interference Cancellation Accuracy

International audienceSpatial modulation (SM) as a new Multiple-Input Multiple-Output (MIMO) technique is based on transmitting part of the information by activating different emitting antennas. SM increases spectral efficiency and uses only one radio frequency chain. For full-duplex (FD) communication systems, self-interference (SI) is always a central problem. Therefore, combining FD and SM can drastically reduce the difficulty of Self-interference Cancellation (SIC) because of the single SI chain. A Full Duplex Spatial Modulation (FDSM) system is proposed and an active analog SIC is highlighted in this paper. Moreover, the impact of SIC accuracy on the system performance is studied. The results demonstrate that the accuracy requirement will increase as the INR (Self-interference-to-noise Ratio) increases. The FDSM system is less sensitive than the FD system in presence of high estimated error value. Furthermore, an SI detector is presented to resolve the influence of the number of detect symbols

Analyse comportementale d'un circuit récupérateur d'énergie en présence de signaux complexes

International audienceThis paper shows the incidence of the modulation scheme and of the input power on the RF to DC rectifier conversion efficiency. A commercial energy harvesting (EH) P21XXCSR-EVB evaluation board from Powercast Corporation is used as measurement target and several waveforms are employed to evaluate the rectification efficiency. With a continuous wave as reference, QPSK, QAM and OFDM waveforms usage demonstrates that digital modulated signals can lead to a better efficiency. Thus, by selecting a high peak to average power ratio (PAPR), and under certain conditions, the performances of the energy harvesting circuit are enhanced.Cet article montre l'incidence du choix de la modulation et de la puissance du signal d'entrée sur l'efficacité d'une conversion RF-DC d'un circuit récupérateur d'énergie. Un circuit commercial de la société Powercast, le convertisseur P21XXCSR-EVB, est utilisé comme système récupérateur d'énergie RF et plusieurs formes d'onde sont générées afin de tester l'efficacité du redresseur. Avec comme référence une onde sinusoïdale, l'utilisation des formes d'ondes de type QPSK, QAM et OFDM montrent qu'un signal modulé permet d'atteindre une meilleure efficacité. Ainsi, en choisissant un rapport PAPR élevé, et sous certaines conditions, les performances du redresseur sont améliorées

Smart Anything - Comment alimenter des milliards d'objets connectés ?

Il est devenu évident depuis des années, même pour le simple amateur de nouvelles technologies, que le nombre des systèmes utilisant une connexion sans fil ne fait qu’augmenter. Les usages liés au nomadisme ou même simplement à la disparition de câblesjugés encombrants ou inesthétiques poussent à développer encore et toujours de nouvelles interfaces radio adaptées aux contraintes amenées par lesdits usages. Mais au-delà même des usages classiques de la connexion de l’humain au monde numérique, l’explosion de l’internetdes objets (plus souvent dénommé IoT, de l’anglais Internet of Things) voit une explosion du nombre d’équipements connectés, équipements ayant des caractéristiques de taille, coût, débit, cycle et autonomie extrêmement variées. Cette tendance se trouve d’ailleurs parfaitement illustrée au travers de l’initiative européenne Smart Everything Anywhere qui démontre cette volonté d’offrir une connectivité dans tous les domaines.La multitude et la diversité des objets connectés remettent en cause les méthodes classiques d’échange d’informations entre les nœuds. Le réseau devra composer avec un environnement changeant qui n’est pas maîtrisé en profondeur. L’interconnexion des objets connectés entraine des changements technologiques radicaux qui métamorphosent le cadre existant. Que ce soit dans le domaine grand public, dans le domaine médical, pour l’industrie 4.0, les bâtiments intelligents ou même les villes intelligentes, tous ces équipements ont au moins en commun une chose essentielle : pour communiquer, ils ont besoin d’énergie.Un enjeu majeur du Smart Anything sera donc de garantir l’alimentation énergétique de ces milliards d’objets connectés, tout en en minimisant l’impact économique et écologique. Il est dès lors indispensable de dimensionner au mieux le système global en fonction des besoins essentiels de l’application. Les métriques classiques de performance (débit, latence, portée, QoS...) doivent être pondérées par de nouveaux critères : coût énergétique de l’information, autonomie, type d’alimentation ou même possibilité de maintenance du système et analyse du cycle de vie

Theoretical BER Evaluation of Passive RFID Tag-To-Tag Communications

International audienceThe concept of UHF RFID passive tag-to-tag communication has been introduced and opens new promising perspectives in the field of Internet-of-Things. This concept enables two powerless tags to exchange information using an external source. Moreover, a simulation framework has been proposed as a tool allowing the performance evaluation of tag-to-tag radio links in terms of Bit Error Rate (BER). The aim of this paper is to provide a theoretical framework for BER estimation. The theoretical framework takes into account various parameters such as modulation rate, receivers topology and the electromagnetic coupling of the tags. Furthermore, in order to validate the obtained results, they are compared with the ones obtained by realistic simulations

Low complexity antenna diversity front-end: Use of code multiplexing

International audienceIn this paper, we address the architecture of an antenna diversity receiver and we aim to reduce the complexity of the analog front-end. To this end, an innovative architecture is introduced based on code multiplexing. This architecture uses the direct sequence spread spectrum technique in order to multiplex the different antennas contributions through a single demodulator. Simulation and measurement results show that, in a Gaussian case, the bit error rate does not increase so much with the multiplexing. The complexity evaluation shows that the proposed architecture significantly reduces the power consumption of the front-end

Combination of Digital Self-Interference Cancellation and AARFSIC for Full-Duplex OFDM Wireless

International audienceFull-Duplex radio provides many benefits beyond improving spectral efficiency. However, canceling the self-interference completely is a big challenge behind Full-Duplex wireless. Although many intelligent efforts devote to active analog radio frequency self-interference cancellation (AARFSIC), the power of the residual self-interference (SI) after the AARFSIC is still much stronger than that of the receiver thermal noise. In this paper, we first study deeply the AARFSIC and "dig" the core problem that causing the residual SI, and then propose a digital self-interference cancellation in time domain (DSICT) to complement AARFSIC for the Full-Duplex OFDM wireless. The ADS-Matlab co-simulation results demonstrate the actual performance and show that the residual SI after the AARFSIC can be canceled completely by employing the proposed DSICT

Power Consumption Optimization in Multi-mode Mobile Relay

International audienceMulti-mode is a common feature in current generation terminals, enabling the user to stay connected at any time. By selecting an appropriate standard, multi-mode can reduce terminal power consumption. Software Defined Radio is an enabler towards multi-mode for the next generation of terminals. In such a radio, communication modes are implemented by a general processor through digital functions, instead of dedicated chips. Providing access to users in bad conditions through relays, is another solution to reduce power consumption. We look at multi-mode relaying, where a mobile terminal, connected to an UMTS base station, acts as an 802.11g-relay for those users. In this paper, we evaluate the algorithmic complexity of 802.11g and UMTS to estimate the power consumption of a Software Defined Radio. We propose a multi-mode relay scheme using such terminals, with the purpose of minimizing the global power consumption. Finally, we enounce different rules to maximize the local and global power gain by implementing multi-mode relays

Low Power Multistandard Simultaneous Reception Architecture

International audienceIn this paper, we address the architecture of multistandard simultaneous reception receivers and we aim at improving both the complexity and the power consumption of the analog front-end. To this end we propose an architecture using the double orthogonal translation technique in order to multiplex two received signals. A study case concerning the simultaneous reception of 802.11g and UMTS signals is developed in this article