Ivana Raos - Academia.edu (original) (raw)

Papers by Ivana Raos

ABSTRACT This deliverable presents a detailed specification of the signal processing functions in... more ABSTRACT This deliverable presents a detailed specification of the signal processing functions involved in the advanced {MC-CDMA} physical layer simulation chains that are considered as advanced chains (V1) within the MATRICE project i.e. with advanced algorithms but without channel estimation, synchronisation and system impairments. For each advanced function, a description of algorithms is proposed. These advanced chains will be used for the performance evaluation and may be improved during the project life.

International Conference on Software, Telecommunications and Computer Networks, 2012

A system for simultaneous 2D estimation of rectangular room and transceiver localization is propo... more A system for simultaneous 2D estimation of rectangular room and transceiver localization is proposed. The system is based on two radio transceivers, both capable of full duplex operations (simultaneous transmission and reception). This property enables measurements of channel impulse response (CIR) at the same place the signal is transmitted (generated), commonly known as self-to-self CIR. Another novelty of the proposed system is the spatial CIR discrimination that is possible with the receiver antenna design which consists of eight sectorized antennas with 45° aperture in the horizontal plane and total coverage equal to the isotropic one. The dimensions of a rectangular room are reconstructed directly from spatial radio impulse responses by extracting the information regarding round trip time (RTT). Using radar approach estimation of walls and corners positions is derived. Tests using measured data were performed, and the simulation results confirm the feasibility of the approach.

(Max 400 word) Starting in May 2008, N4C is a 36 month research project in the Seventh Framework ... more (Max 400 word) Starting in May 2008, N4C is a 36 month research project in the Seventh Framework Programme (www.cordis.lu/fp7). In cooperation between users in northern Sweden and Kočevje region in Slovenian mountain and partners, the project will design and experiment with an architecture, infrastructure and applications in field trials and build two test beds in order to improve the living conditions of some remote communities. Therefore, this is clearly a user-oriented project. This particular document describes the main activity carried out in WP6 regarding the animal tracking application. Two partners, Tannak and UPM, have been working in a coordinated way as final users and designers in order to propose, validate and test different approaches. On one hand, there exists an initiative from Tannak providing one tracking system whose main developments were carried out before the start of the current project. In this document, we label this system as battery-powered secondary nodes. This deliverable comprises the technical description and also some preliminary tests carried out in the winter 2009 where the system was initially checked, minor modifications were required and some improvements regarding the user " s point of view were performed. On the other hand, UPM has developed a different alternative named self-powered secondary nodes where we are using a kinetic generator in order to avoid the massive deployment of batteries. This system, completely developed within this project, has a very different performance because transmissions occur according to the animal movement. Several prototypes and tests are described. Dissemination level Level PU = Public PP = Restricted to other programme participants (including the Commission Services). RE = Restricted to a group specified by the consortium (including the Commission Services). CO = Confidential, only for members of the consortium (including the Commission Services).

Las secuencias esferoidales prolongadas (SEP) forman conjunto de secuencias ortonormales y con bu... more Las secuencias esferoidales prolongadas (SEP) forman conjunto de secuencias ortonormales y con buenas propiedades de concentracion de energia en intervalo o en una banda de frecuencia. Estas secuencias se han aplicado en varios sistemas de banda ancha para proponer soluciones viables a diversos tipos de problemas MC/OQAM: la concentracion de pulsos en sistemas multiportadora favorece su robustez frente a la dispersion temporal y frecuencial del canal, igual que por el nivel de interferencia que puede causar en los sistemas adyacentes en banda de frecuencia. La senal OFDM/OQAM se puede interpretar como una transmision en dos rejillas que se solapan, pero son ortogonales, ya que una tiene los datos modulados estrictamente reales y otra imaginarios. Por lo tanto, se manda la misma cantidad de informacion como en el caso de OFDM sin tiempo de guarda, pero por las formas de ondas bien concentradas, y por lo tanto, mas resistentes a la dispersion temporal y frecuencial del canal. Las form...

A heterogeneous network, mainly based on nodes that use harvested energy to self-energize, is pre... more A heterogeneous network, mainly based on nodes that use harvested energy to self-energize, is presented, and its use is demonstrated. The network, mostly kinetically powered, has been used for the localization of herds in grazing areas under extreme climate conditions. The network consists of secondary and primary nodes. The former, powered by a kinetic generator, take advantage of animal movements to broadcast a unique iden-tifier. The latter are battery-powered and gather secondary-node-transmitted information to provide it, along with position and time data, to a final base station in charge of the animal monitoring. Because a limited human interaction is desirable, the aim of this network is to reduce the battery count of the system.

2008 16th European Signal Processing Conference, 2008

Virtual MIMO configuration, a common model for cooperation in sensor networks, trades off coopera... more Virtual MIMO configuration, a common model for cooperation in sensor networks, trades off cooperation cost in front of MIMO gains. Most of proposed approaches rely mainly on the fact that cooperation at transmitter side alone seems to be much more powerful than receiver cooperation alone. The scenario that is analysed in this contribution includes the effect of interference of other clusters located closely that clearly degrades whatever cooperation type aforementioned. Under these circumstances, the use of additional sensors at receiver side helps creating a set of virtual beamformers, optimally designed to cancel the undesired signal. So, transmitter cooperation based on Dirty Paper Coding (DPC) strategies to minimize intra-cluster interference and virtual beamformers to minimize inter-cluster interference seems to be a very satisfactory combination.

2006 14th European Signal Processing Conference, 2006

OFDM/OQAM is spectrally efficient multicarrier (MC) system, robust to mobile channel (time and fr... more OFDM/OQAM is spectrally efficient multicarrier (MC) system, robust to mobile channel (time and frequency) variability thanks to pulse shaping. In this contribution, pulse shaping with discrete non-orthogonal pulse based on Discrete Prolate Spheroidal Sequence (DPSS), is proposed. DPSS, being the most concentrated pulse out of all sequences of the same length, is the natural choice for pulse shaping. The novelty of the analysis lies in the discovery of quasi-orthogonality property of DPSS to its time and frequency shifts. DPSS pulse analysis shows that this property is valid in the case of short pulse of the single MC symbol length. MC/OQAM system performance with DPSS and other pulses types is analyzed by simulation confirming the quasi-orthogonality of DPSS. The advantage of using the most concentrated pulse is shown in terms of interference that two MC/OQAM systems in adjacent frequency bands cause one to another. Simulations also show that DPSS permits smaller frequency separatio...

ABSTRACT A system for anchor-less self-positioning and simultaneous 2D estimation of rectangular ... more ABSTRACT A system for anchor-less self-positioning and simultaneous 2D estimation of rectangular room dimensions is proposed. The system is based on narrowband transceiver capable of simultaneous transmission and reception. The transmission is generated at omnidirectional antenna, while eight sectorized antennas with 45deg apertures in horizontal are used for reception. The full duplex property enables measurements of spatially discriminated channel impulse response (CIR) at the same place where the signal is originated. Hence, by using radar approach, the presence of walls and corners can be evaluated based on round trip time (RTT) measurements. The novel contribution of this paper includes position estimation confidence indicator defined as instantaneous received power of the CIR??s strongest element. Additionally, it is assumed that a transceiver is a part of an ??intelligent?? mobile robot platform capable of moving, updating its position, and keeping track of past positions along with the corresponding measurement data. We propose a new mobility model, focused on efficient exploration of an unknown environment by moving towards the walls according to the corresponding confidence indicators values. Simulations inside narrowband synthetic test environment are performed and the performances of localization and room dimension estimates, as a function of number of observations, are evaluated. Index Terms ?? full duplex antennas, channel impulse response, indoor, mapping, mobility model, radar approach estimation, ray tracing, rectangular rooms, round trip time, simultaneous localization and mapping, sectorized narrowband antennas, selfpositioning, spatial CIR discrimination, transceiver localization

IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009), 2009

This paper deals with the design of an integrated system that is able to transmit data with high ... more This paper deals with the design of an integrated system that is able to transmit data with high data rate and also high quality. However, the main feature is not the enhanced performance but the objective of providing a nearly permanent and reliable communication over time. In order to overcome the long term fading, a probe modem is simultaneously monitoring all the available channels and ranking them in terms of feasibility. A general manager named ALMA (Automatic Link MAnagement) detects when the current transmission is being degraded and in a transparent way to the user, decides when and how the channel change happens. To make this approach feasible, we have developed our own broadband transceiver that is able to transmit / receive simultaneous streams. In this paper we will describe the performance of the probe modem, the criteria and strategy for channel changing and the performance of the stable data modem.

2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)., 2000

Modified digital prolate functions (DPF) are addressed in this paper, applied as waveforms for do... more Modified digital prolate functions (DPF) are addressed in this paper, applied as waveforms for downlink MC-CDMA systems and providing higher transmission rates. Those waveforms, thanks to their double orthogonality and energy concentration in restricted interval properties, enable specific processing at the receiver. Design and analysis of advanced receivers exploiting the abovementioned DPF properties and computer simulations that demonstrate their performance improvement compared to MC-CDMA system with Hadamard codes are presented.

12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012), 2012

The reliability of bidirectional communication link can be guaranteed with Automatic Repeat Reque... more The reliability of bidirectional communication link can be guaranteed with Automatic Repeat Request Procedures (ARQ). The standard STANAG 5066 describes the ARQ procedure for HF communications that can either be applied to existing HF physical layers modems or adapted to future physical layer designs. In this contribution the physical layer parameters of an HF modem (HFDVL), developed by the authors over the last decade, are chosen to optimize the performance of the ARQ procedure described in STANAG 5066. Besides the interleaving length, constellation size and coding type, the OFDM-based HFDVL modem permits the selection of the number of receiver antennas. It will be shown that this parameter gives additional degrees of freedom and permits reliable communication over low SNR HF communication links.

12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012), 2012

Multi-carrier modulations are widely employed in ionospheric communications to mitigate the adver... more Multi-carrier modulations are widely employed in ionospheric communications to mitigate the adverse effects of the HF channel. In this paper we show how performance achieved by these modulations can be further increased by means of CSIbased precoding techniques in the context of our research on interactive digital voice communications. Depending on communication constraints and channel parameters, we will show which of the studied modulations and precoding techniques to select so that to maximise performance.

International Conference on Software, Telecommunications and Computer Networks, 2012

2008 16th European Signal Processing Conference, 2008

2006 14th European Signal Processing Conference, 2006

IET 11th International Conference on Ionospheric Radio Systems and Techniques (IRST 2009), 2009

2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)., 2000

12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012), 2012