Open Topics

Vol. 67, n° 1-2, January-February 2012
Content available on Springerlink

Toward automatic GIS–video initial registration

Gaël Sourimant1, Thomas Colleu1, Vincent Jantet1, Luce Morin2  and Kadi Bouatouch3
INRIA Rennes Bretagne Atlantique
2 IETR/INSA Rennes
3 Université Rennes 1

Abstract In the context of registration between videos and geographic information system (GIS)-based 3D building models — for instance in augmented reality applications — we propose a solution to one of the most critical problems, namely the registration initialization. Successful automatic 2D/3D matching is achieved by combining two context-dependent improvements. On one hand, we associate semantic information to the low-level primitives we used to reduce the problem complexity. On the other hand, we avoid false initial registration solutions by analyzing the convergence of the iterative pose computation in a RANSAC framework. We require that videos are acquired together with global positioning system measures. We also present how such a registration can be exploited, once it has been performed for the whole video. Textures of visible buildings are extracted from the images. A new algorithm for façade texture fusion based on statistical analysis of the texels color is presented. It allows us to remove from the final textures all occluding objects in front of the viewed building façades.

Keywords Data registration – Urban modeling – Texture synthesis – GPS – GIS – Ransac

On the optimality of max–min fairness in resource allocation

Angelo Coluccia1, Alessandro D’Alconzo2 and Fabio Ricciato1,2
Universita del Salento, Lecce, Italy
2 Forschungszentrum Telekommunikation Wien (FTW), Austria

Abstract In this work, a basic resource allocation (RA) problem is considered, where a fixed capacity must be shared among a set of users. The RA task can be formulated as an optimization problem, with a set of simple constraints and an objective function to be minimized. A fundamental relation between the RA optimization problem and the notion of max–min fairness is established. A sufficient condition on the objective function that ensures the optimal solution is max–min fairness is provided. Notably, some important objective functions like least squares and maximum entropy fall in this case. Finally, an application of max–min fairness for overload protection in 3G networks is considered.

Keywords  Resource allocation – Max–min fairness – Optimization problems

Performances of chaos-coded modulation concatenated with Alamouti’s space–time block code

Naim Khodor, Jean-Pierre Cances, Vahid Meghdadi and Raymond Quere
XLIM Dept C2S2 UMR CNRS 6172, France

Abstract Recently, some works have shown that it was possible to obtain quite good bit error rate performances over an additive white Gaussian noise channels with chaotic systems. In this research field, this paper proposes new insights for the chaos-coded modulation (CCM) schemes originally proposed by Kozic et al. (2003; IEEE Trans Circuits Syst Regul Pap 53:2048–2059, 2006). A detailed study of the distance spectrum of such schemes is proposed and an approximation of its distribution by means of Gaussian or Rayleigh mixtures is given. Furthermore, using these approximate distributions, a complete study of the performances of these CCM schemes when they are concatenated with a space–time block code is proposed. Accurate bounds are obtained even in the case of time-selective channels.

Keywords  Chaos-coded modulation – Expectation maximization – Gaussian or Rayleigh mixtures – Space–time block codes – Diversity gain – Pairwise error probability – Time-selective fading channels

Spatio-temporal channel characterization: theoretical framework and applications in MIMO system design

Viet-Ha Pham1, Jean-Yves Chouinard1, Dominic Grenier1, Huu-Tue Huynh2, Xianbin Wang3 and Yiyan Wu4
1 Université Laval, Québec, Canada
2 Bac Ha International University, Hanoi, Vietnam
3 University of Western Ontario, London, Canada
4 Communications Research Centre Canada, Ottawa

Abstract The utilization of multiple antennas and space–time codes in multiple-input and multiple-output (MIMO) communication systems significantly improves the transmission channel capacity without using additional bandwidth and power. The improvement is achieved by decomposing the spatial structure of transmission channels and performing appropriate temporal and spatial multiplexing. In this paper, we propose a novel theoretical framework for MIMO channel modeling and characterization in order to facilitate the MIMO system design and performance evaluation. The channels are represented in space, time, wave vector, and frequency domains while the space–time and wave vector–frequency interdependences are considered. A realization of the theoretical framework, in a form of a practical framework, is also proposed to address the channel modeling and characterization at both transmitter and receiver sides. The utilization of the practical framework in MIMO communication system design is discussed to illustrate its applications in realistic scenarios. The angle of arrival estimation based on the proposed practical framework using field test measurement data is also presented as illustrative examples.

Keywords Spatio-temporal characterization – MIMO system design – Angle of arrival estimation – Multidimensional Fourier transform – MIMO channel characterization and modelin

Satellite image compression by concurrent representations of wavelet blocks

Xavier Delaunay1, Marie Chabert2, Vincent Charvillat2 and Géraldine Morin2
1 NOVELTIS, Ramonville-Saint-Agne, France
IRIT/ENSEEIHT, Toulouse, France

Abstract This paper proposes a complete compression and coding scheme for on-board satellite applications considering the main on-board constraints: low computational power and easy bit rate control. The proposed coding scheme improves the performance of the current Consultative Committee for Space Data Systems (CCSDS) recommendation for a low additional complexity. We consider post-transforms in the wavelet domain, select the best representation for each block of wavelet coefficients, and encode it into an embedded bit stream. After applying a classical wavelet transform of the image, several concurrent representations of blocks of wavelet coefficients are generated. The best representations are then selected according to a rate-distortion criterion. Finally, a specific bit-plane encoder derived from the CCSDS recommendation produces an embedded bit stream ensuring the easy rate control required. In this article, both the post-transforms and the best representation selection have been adapted to the low complexity constraint, and the CCSDS coder has been modified to compress post-transformed representations.

Keywords  Image coding – Satellite applications – Transform coding – Wavelet transforms – Hadamard transform

An analytical model for jitter in IP networks

Hamza Dahmouni1, André Girard2 and Brunilde Sansò3
1 Institut National des Postes et Télécommunications, Rabat, Morocco
2 INRS-EMT and GERAD, Montreal, Québec, Canada
3 Ecole polytechnique de Montreal and GERAD, Montreal, Québec, Canada

Abstract Traditionally, IP network planning and design is mostly based on the average delay or loss constraints which can often be easily calculated. Jitter, on the other hand, is much more difficult to evaluate, but it is particularly important to manage the QoS of real-time and interactive services such as VoIP and streaming video. In this paper, we present simple formulas for the jitter of Poisson traffic in a single queue that can be quickly calculated . It takes into account the packets delay correlation and also the correlation of tandem queues that have a significant impact on the end-to-end jitter. We then extend them to the end-to-end jitter of a tagged stream based on a tandem queueing network. The results given by the model are then compared with event-driven simulations. We find that they are very accurate for Poisson traffic over a wide range of traffic loads and more importantly that they yield conservative values for the jitter so that they can be used in network design procedures. We also find some very counter-intuitive results. We show that jitter actually decreases with increasing load and the total jitter on a path depends on the position of congested links on that path. We finally point out some consequences of these results for network design procedures.

Keywords  Jitter model – Traffic engineering – IP network planning

Design and implementation for integrated services orchestration bus using SCA over heterogeneous networks

Cheng Bo, Zhang Yang, Ye Bo, Zhou Peng and Chen Junliang
Beijing University of Posts and Telecommunications, Beijing, China

Abstract As the telecom and IT industries converge, pressure is mounting for convergence of service across the two domains, and future integrated services in the telecom domain are subject to specific requirements such as support for end-to-end communication sessions and mechanisms for service interaction across technological borders including telecom, enterprise, and Internet services. This paper provides an integrated services orchestration bus to handle the interoperation and compositions of services from the different domain and focus on the components lifecycle management, normalized message routing, normalized message parsing and mapping, events serialization processing, JNDI register management, and deploy unit. The multimedia conferencing-use case scenario is illustrated, and also the performance is measured and analyzed. Finally, we give the conclusions and future work.

Keywords  Integrated services – Orchestration bus – Service component architecture – Heterogeneous networks