Showing papers by "Orange S.A. published in 2008"

A Dynamic Clustering Approach in Wireless Networks with Multi-Cell Cooperative Processing

Abstract: Multi-cell cooperative processing (MCP) has recently attracted a lot of attention because of its potential for co-channel interference (CCI) mitigation and spectral efficiency increase. MCP inevitably requires increased signaling overhead and inter-base communication. Therefore in practice, only a limited number of base stations (BSs) can cooperate in order for the overhead to be affordable. The intrinsic problem of which BSs shall cooperate in a realistic scenario has been only partially investigated. In this contribution linear beamforming has been considered for the sum-rate maximisation of the uplink. A novel dynamic greedy algorithm for the formation of the clusters of cooperating BSs is presented for a cellular network incorporating MCP. This approach is chosen to be evaluated under a fair MS scheduling scenario (round-robin). The objective of the clustering algorithm is sum-rate maximisation of the already selected MSs. The proposed cooperation scheme is compared with some fixed cooperation clustering schemes. It is shown that a dynamic clustering approach with a cluster consisting of 2 cells outperforms static coordination schemes with much larger cluster sizes.

Channel estimation methods for preamble‐based OFDM/OQAM modulations

Abstract: In this paper, OFDM/OQAM is proposed as an alternative to conventional OFDM with cyclic prefix (CP) for transmission over multi-path fading channels. Two typical features of the OFDM/OQAM modulation are the absence of a guard interval (GI) and the fact that the orthogonality property only holds in the real field and for a distortion-free channel. Thus, the classical channel estimation (CE) methods used for OFDM cannot be directly applied to OFDM/OQAM. Therefore, we propose an analysis of the transmission of an OFDM/OQAM signal through a time-varying multi-path channel and we derive two new CE methods. The first proposed method only requires the use of pair of real pilots (POP). In a second method, named interference approximation method (IAM), we show how the imaginary interference can be used to improve the CE quality. Several preamble variants of the IAM are compared with respect to the resulting instantaneous power. Finally, the performance results obtained for the transmission of an OFDM/OQAM signal through an IEEE 802.22 channel using the POP method and three variants of IAM are compared to those obtained with CP-OFDM. Copyright © 2008 John Wiley & Sons, Ltd.

RD Optimized Coding for Motion Vector Predictor Selection

Abstract: The H.264/MPEG4-AVC video coding standard has achieved a higher coding efficiency compared to its predecessors. The significant bitrate reduction is mainly obtained by efficient motion compensation tools, as variable block sizes, multiple reference frames, 1/4-pel motion accuracy and powerful prediction modes (e.g., SKIP and DIRECT). These tools have contributed to an increased proportion of the motion information in the total bit- stream. To achieve the performance required by the future ITU-T challenge, namely to provide a codec with 50% bitrate reduction compared to the current H.264, the reduction of this motion information cost is essential. This paper proposes a competing framework for better motion vector coding and SKIP mode. The predictors for the SKIP mode and the motion vector predictors are optimally selected by a rate-distortion criterion. These methods take advantage from the use of the spatial and the temporal redundancies in the motion vector fields, where the simple spatial median usually fails. An adaptation of the temporal predictors according to the temporal distances between motion vector fields is also described for multiple reference frames and B-slices options. These two combined schemes lead to a systematic bitrate saving on Baseline and High profile, compared to an H.264/MPEG4-AVC standard codec, which reaches up to 45%.

Behavioral detection of malware: from a survey towards an established taxonomy

Abstract: Behavioral detection differs from appearance detection in that it identifies the actions performed by the malware rather than syntactic markers. Identifying these malicious actions and interpreting their final purpose is a complex reasoning process. This paper draws up a survey of the different reasoning techniques deployed among the behavioral detectors. These detectors have been classified according to a new taxonomy introduced inside the paper. Strongly inspired from the domain of program testing, this taxonomy divides the behavioral detectors into two main families:simulation-basedandformaldetectors.Insidethese families, ramifications are then derived according to the data collection mechanisms, the data interpretation, the adopted model and its generation, and the decision support.

Analysis of RF exposure in the head tissues of children and adults

Abstract: This paper analyzes the radio frequencies (RF) exposure in the head tissues of children using a cellular handset or RF sources (a dipole and a generic handset) at 900, 1800, 2100 and 2400 MHz. Based on magnetic resonance imaging, child head models have been developed. The maximum specific absorption rate (SAR) over 10 g in the head has been analyzed in seven child and six adult heterogeneous head models. The influence of the variability in the same age class is carried out using models based on a morphing technique. The SAR over 1 g in specific tissues has also been assessed in the different types of child and adult head models. Comparisons are performed but nevertheless need to be confirmed since they have been derived from data sets of limited size. The simulations that have been performed show that the differences between the maximum SAR over 10 g estimated in the head models of the adults and the ones of the children are small compared to the standard deviations. But they indicate that the maximum SAR in 1 g of peripheral brain tissues of the child models aged between 5 and 8 years is about two times higher than in adult models. This difference is not observed for the child models of children above 8 years old: the maximum SAR in 1 g of peripheral brain tissues is about the same as the one in adult models. Such differences can be explained by the lower thicknesses of pinna, skin and skull of the younger child models.

Variability analysis of SAR from 20 MHz to 2.4 GHz for different adult and child models using finite-difference time-domain

Abstract: This paper deals with the variability of body models used in numerical dosimetry studies. Six adult anthropomorphic voxel models have been collected and used to build 5-, 8- and 12-year-old children using a morphing method respecting anatomical parameters. Finite-difference time-domain calculations of a specific absorption rate (SAR) have been performed for a range of frequencies from 20 MHz to 2.4 GHz for isolated models illuminated by plane waves. A whole-body-averaged SAR is presented as well as the average on specific tissues such as skin, muscles, fat or bones and the average on specific parts of the body such as head, legs, arms or torso. Results point out the variability of adult models. The standard deviation of whole-body-averaged SAR of adult models can reach 40%. All phantoms are exposed to the ICNIRP reference levels. Results show that for adults, compliance with reference levels ensures compliance with basic restrictions, but concerning children models involved in this study, the whole-body-averaged SAR goes over the fundamental safety limits up to 40%.

Distribution of RF energy emitted by mobile phones in anatomical structures of the brain.

Abstract: The rapid worldwide increase in mobile phone use in the last decade has generated considerable interest in possible carcinogenic effects of radio frequency (RF). Because exposure to RF from phones is localized, if a risk exists it is likely to be greatest for tumours in regions with greatest energy absorption. The objective of the current paper was to characterize the spatial distribution of RF energy in the brain, using results of measurements made in two laboratories on 110 phones used in Europe or Japan. Most (97–99% depending on frequency) appears to be absorbed in the brain hemisphere on the side where the phone is used, mainly (50–60%) in the temporal lobe. The average relative SAR is highest in the temporal lobe (6–15%, depending on frequency, of the spatial peak SAR in the most exposed region of the brain) and the cerebellum (2–10%) and decreases very rapidly with increasing depth, particularly at higher frequencies. The SAR distribution appears to be fairly similar across phone models, between older and newer phones and between phones with different antenna types and positions. Analyses of risk by location of tumour are therefore important for the interpretation of results of studies of brain tumours in relation to mobile phone use.

Indoor Power-Line Communications Channel Characterization Up to 100 MHz—Part I: One-Parameter Deterministic Model

Abstract: Advanced communication technologies have allowed the power-line-communication (PLC) channel to be a transmission medium that enables the transfer of high-speed digital data over the classical indoor electrical wires. The development of PLC systems for Internet, voice, and data services requires measurement-based models of the transfer characteristics of the mains network suitable for performance analysis by simulation. This paper presents a deterministic model describing the magnitude and phase of complex transfer functions of power-line networks using only one parameter. First, a PLC channel classification is realized, and an average magnitude and phase channel model by class is proposed. Second, the multipath characteristic of PLC channels is introduced. A statistical-based channel magnitude generator is built, and a group delay-based phase model is suggested.

Automated Diagnosis for UMTS Networks Using Bayesian Network Approach

Abstract: This paper presents an automated diagnosis in troubleshooting (TS) for Universal Mobile Telecommunications System (UMTS) networks using a Bayesian network (BN) approach. An automated diagnosis model is first described using the Naive Bayesian Classifier. To increase the performance of the diagnosis model, the entropy minimization discretization (EMD) method is incorporated into the model to select optimal segments for the discretization of the input symptoms. In the first phase, the diagnosis model is constructed using a dynamic simulator. The simulator TS platform allows generation of a large amount of data required to study the relations between faults and symptoms. In the second phase, the diagnosis model is adapted to a real UMTS network using counters and key performance indicators (KPIs) recovered from an Operations and Maintenance Center (OMC). Results for the automated diagnosis using both network simulator and real UMTS network measurements illustrate the efficiency of the proposed TS approach and its importance to mobile network operators.

60-GHz Photonic Millimeter-Wave Link for Short- to Medium-Range Wireless Transmission Up to 12.5 Gb/s

Abstract: In this paper, a 60-GHz photonic millimeter-wave link system for short- to medium-range broadband wireless data transmission is investigated. The system employs advanced mm-wave photonic components and radio-over-fiber (RoF) techniques for the generation of a DSB-SC optical mm-wave carrier and its subsequent on-off-keying modulation and transmission. For short-range applications, we have constructed a compact wireless RoF transmitter consisting of a high-frequency photodiode and a mm-wave antenna only. This system achieved error-free (BER=10-9, 231-1 PRBS, NRZ) in-door transmission of 12.5-Gb/s signals over wireless distances up to 3.1 m with a receiver sensitivity as low as - 45.4 dBm . For fixed wireless access (FWA) requiring a bit error rate of 10-4, the maximum transmission distance for 12.5 Gb/s is increased up to 5.8 m. For medium-range broadband wireless transmission an electrical radio-frequency (RF) amplifier was employed in the RoF transmitter. Here we achieved 7.5-Gb/s error-free transmission in out-door line-of-sight experiments over wireless distances of up to 36 m. Based upon the experimental results, we expect that the maximum wireless distance the system could accommodate for 12.5 Gb/s is in the kilometer range when using high-gain antennas and an RF transmitter amplifier with a sufficient bandwidth.

System and method for managing widgets

Abstract: The invention relates to method for managing a set of widgets displayed on the graphical user interface (GUI) of a device, said method comprising the acts of receiving contextual data from the device, querying with the received contextual data a repository of widget configurations for the set of widgets, said widgets configurations being described in said repository as functions of the possible contextual data values, displaying the set of widgets using the configuration that match the received contextual data.

Designing Specific Weighted Similarity Measures to Improve Collaborative Filtering Systems

Abstract: The aim of collaborative filteringis to help usersto find itemsthat they should appreciate from huge catalogues. In that field, we can distinguish user-basedfrom item-basedapproaches. The former is based on the notion of user neighbourhoods while the latter uses item neighbourhoods. The definition of similaritybetween users and items is a key problem in both approaches. While traditional similarity measures can be used, we will see in this paper that bespoke ones, that are tailored to type of data that is typically available (i.e. very sparse), tend to lead to better results. Extensive experiments are conducted on two publicly available datasets, called MovieLensand Netflix. Many similarity measures are compared. And we will show that using weighted similarity measures significantly improves the results of both user- and item-based approaches.

End-to-End Quality of Service Over Heterogeneous Networks

Abstract: The EuQoS (End-to-End QoS over Heterogeneous Networks) IST Integrated European Project aimed to define a Next Generation Network architecture that builds, uses and manages end-to-end QoS across different administrative domains and heterogeneous networks (UMTS, xDSL, Ethernet, WiFi, Satellite and IP/MPLS). The EuQoS architecture preserves the openness and the decentralized decision model of the actual Internet, runs on off-the-shelf hardware and network equipment, and allows end users to request various services without changing the Application Signaling protocol, while meeting regulators' and users' Net Neutrality requirements. This paper presents the key elements of the EuQoS architecture and describes the main results obtained in field trials performed on a fully-functional EuQoS system prototype developed over a pan-European testbed. Furthermore, the paper discusses the main strengths of the system and the issues related to its actually deployment on a large scale, from both technical and market points of view.

Opportunistic interference alignment in MIMO interference channels

Abstract: We present two interference alignment techniques such that an opportunistic point-to-point multiple input multiple output (MIMO) link can reuse, without generating any additional interference, the same frequency band of a similar pre-existing primary link. In this scenario, we exploit the fact that under power constraints, although each radio maximizes independently its rate by water-filling on their channel transfer matrix singular values, frequently, not all of them are used. Therefore, by aligning the interference of the opportunistic radio it is possible to transmit at a significant rate while insuring zero-interference on the pre-existing link. We propose a linear pre-coder for a perfect interference alignment and a power allocation scheme which maximizes the individual data rate of the secondary link. Our numerical results show that significant data rates are achieved even for a reduced number of antennas.

2 dB Better Than CP-OFDM with OFDM/OQAM for Preamble-Based Channel Estimation

Abstract: OFDM/OQAM is a special type of multi-carrier modulation that can be considered as an alternative to conventional OFDM with cyclic prefix (CP) for transmission over multi-path fading channels. Indeed, as it requires no CP, it has the advantage of a theoretically higher spectral efficiency. Furthermore, efficient pulse shaping can also be easily implemented with OFDM/OQAM. However, the classical channel estimation methods used for OFDM cannot be directly applied to OFDM/OQAM. In this paper we present an analysis of this problem and we introduce a new preamble-based channel estimation method. The performance results are obtained either by considering an IEEE802.22 channel model or regarding to the channel delay spread variation of a two-tap channel. The proposed OFDM/OQAM channel estimation method is evaluated, in both scenarios, using different pulse shaping and taking conventional CP-OFDM as reference.

Automatic profile-based avatar generation

Abstract: A System, method nd device for providing an avatar for interaction in a virtual environment. A user provides a user identifier and a user profile not associated with an avatar is retrieved based on the user identifier. Avatar characteristics are determined based on the retrieved user profile. The virtual environment is rendered with an avatar based on the determined avatar characteristics. The retrieved user profile may include at least one of a default profile, an advertiser supplied profile, a profile associated with a given user and a profile associated with the virtual environment.

Tracking Web spam with HTML style similarities

Abstract: Automatically generated content is ubiquitous in the web: dynamic sites built using the three-tier paradigm are good examples (e.g., commercial sites, blogs and other sites edited using web authoring software), as well as less legitimate spamdexing attempts (e.g., link farms, faked directories).Those pages built using the same generating method (template or script) share a common “look and feel” that is not easily detected by common text classification methods, but is more related to stylometry.In this work we study and compare several HTML style similarity measures based on both textual and extra-textual features in HTML source code. We also propose a flexible algorithm to cluster a large collection of documents according to these measures. Since the proposed algorithm is based on locality sensitive hashing (LSH), we first review this technique.We then describe how to use the HTML style similarity clusters to pinpoint dubious pages and enhance the quality of spam classifiers. We present an evaluation of our algorithm on the WEBSPAM-UK2006 dataset.

Analytical Analysis of the Coverage of a MBSFN OFDMA Network

Abstract: In this paper, we develop a novel analytical model to examine the coverage and capacity of MBSFN (MBMS over a single frequency network) OFDMA, proposed to deliver TV services to mobile users in forthcoming 3G LTE networks. First, analytical expression for SINR at a given point in a cell is derived, which takes into account the SFN gain and propagation delay values. Next, the shadowing effect of propagation on MBSFN is considered. In addition, dynamic MBSFN, an advanced MBSFN technique, in which the network cells are dynamically activated based on user traffic, is modelled. Finally, the performance of MBSFN is evaluated based on the proposed analytical model. This includes the investigation of MBSFN related parameters such as the modulation and coding scheme (MCS) values and the length of cyclic prefix, as well as the verification on the accuracy of the proposed model and the impact of shadowing. Dynamic MBSFN is also analyzed and we show its effect on the coverage for different traffic scenarios.

Channel estimation with scattered pilots in OFDM/OQAM

Abstract: OFDM/OQAM is a multi-carrier modulation scheme that can be considered as an alternative to conventional OFDM with cyclic prefix (CP) for transmission over multi-path fading channels. As it requires no CP, it has the advantage of a theoretically higher spectral efficiency. Furthermore, efficient pulse shaping can also be easily implemented. However, the classical channel estimation methods used for OFDM cannot be directly applied to OFDM/OQAM. In this paper, we present an analysis of this problem and we introduce a channel estimation method using scattered pilots. The performance results are evaluated for a slow varying multi-path channel model. For both scenarios, the results of OFDM/OQAM, using 2 different pulse shaping, are compared to those of CP-OFDM.

Experimental demonstration of 10 Gbit/s upstream transmission by remote modulation of 1 GHz RSOA using Adaptively Modulated Optical OFDM for WDM-PON single fiber architecture

Abstract: We experimentally demonstrate the use of AMOOFDM format for remote modulation of low-bandwidth RSOA as a cost effective solution for 10 Gbit/s upstream transmission in 20 km single fiber WDM-PON architecture.

SStreaMWare: a service oriented middleware for heterogeneous sensor data management

Abstract: Smart sensors are already being used in various application domains such as medical, environmental, urban, domestic and industrial. These applications mostly need data from sensors of different types (temperature, pressure, location, camera, etc.) that may be managed by different software, e.g., proprietary software from manufacturers. Heterogeneous distributed sensor data should then be aggregated in order to obtain more accurate and complete information on real world events. This paper proposes SStreaMWare, a service-oriented middleware for heterogeneous sensor data management. SStreaMWare's simple data schema allows data representation of various types of sensors in a common generic way. Declarative queries can then be formulated according to this schema. Thanks to the service-oriented approach of SStreaMWare, heterogeneity of sensor software is hidden by generic query services, which can be discovered and used dynamically.

Solipsis: A Decentralized Architecture for Virtual Environments

Abstract: Lack of scalability is a key issue for virtual-environment technology, and more generally for any large-scale online experience because it prevents the emergence of a truly massive virtual-world infrastructure (Metaverse) The Solipsis project tackles this issue through the use of peer-to-peer technology, and makes it possible to build and manage a world-scale Metaverse in a truly distributed manner Following a peer-to-peer scheme, entities collaborate to build up a common set of virtual worlds In this paper, we present a first draft of the \sol architecture as well as the communication protocol used to share data between peers The protocol is based on Raynet, an n-dimensional Voronoi-based overlay network Its data-dissemination policy takes advantage of the view-depedent representation of 3D contents Moreover, the protocol effectively distributes the execution of computationally intensive tasks that are usually executed on the server-side, such as collision detection and physics computation Finally, we also present our web component, a 3D navigator that can easily run on terminals with scarce resources, and that provides solutions for smooth transitions between 3D Web and Web 20

Scalable Extended Reach PON

Abstract: Extended reach highly-scalable, fully passive WDM/TDM-PON allows reaching >1000 users along protected 100 km by colorless ONUs, centralized light-generation and control, single-fiber access and remote amplification. ONUs are based on 1.25/2.5/5Gbps-capable RSOA and downstream at 10 Gbps.

Enhanced multiuser random beamforming: dealing with the not so large number of users case

Abstract: We consider the downlink of a wireless system with an M-antenna base station and K single-antenna users. A limited feedback-based scheduling and precoding scenario is considered that builds on the multiuser random beamforming (RBF). Such a scheme was shown to yield the same capacity scaling, in terms of multiplexing and multiuser diversity gain, as the optimal full CSIT-based (channel state information at transmitter) precoding scheme, in the large number of users K regime. Unfortunately, for more practically relevant (low to moderate) K values, RBF yields degraded performance. In this work, we investigate solutions to this problem. We introduce a two-stage framework that decouples the scheduling and beamforming problems. In our scenario, RBF is exploited to identify good, spatially separable, users in a first stage. In the second stage, the initial random beams are refined based on the available feedback to offer improved performance toward the selected users. Specifically, we propose beam power control techniques that do not change the direction of the second-stage beams, offering feedback reduction and performance tradeoffs. The common feature of these schemes is to restore robustness of RBF with respect to sparse network settings (low K), at the cost of moderate complexity increase.

Power control in distributed cooperative OFDMA cellular networks

Abstract: This paper addresses downlink cooperation at a system level. Cooperation between base stations is an alternative to macrodiversity to provide QoS continuity in case of mobility. We propose a radio resource management strategy for the relay channel, made of relayed users identification, resource allocation and power control in an OFDMA-based system. Four scheduling methods are tested for power allocation in inter-cell interference environment: globally optimal, proportional fair, harmonic mean fair and max-min fair. Cooperation brings additional gain, both in terms of throughput and fairness, with all fair schedulers.

A Framework for Dynamic Web Services Composition

Abstract: Dynamic composition of web services is a promising approach and at the same time a challenging research area for the dissemination of service-oriented applications. It is widely recognised that service semantics is a key element for the dynamic composition of Web services, since it allows the unambiguous descriptions of a service’s capabilities and parameters. This paper introduces a framework for performing dynamic service composition by exploiting the semantic matchmaking between service parameters (i.e., outputs and inputs) to enable their interconnection and interaction. The basic assumption of the framework is that matchmaking enables finding semantic compatibilities among independently defined service descriptions. We also developed a composition algorithm that follows a semantic graph-based approach, in which a graph represents service compositions and the nodes of this graph represent semantic connections between services. Moreover, functional and non-functional properties of services are considered, to enable the computation of relevant and most suitable service compositions for some service request. The suggested end-to-end functional level service composition framework is illustrated with a realistic application scenario from the IST SPICE project.

Downlink overhead reduction for Multi-Cell Cooperative Processing enabled wireless networks

Abstract: Multicell cooperative processing (MCP) has been recognised as an efficient technique for increasing spectral efficiency of future cellular systems. However the provided benefits come at the cost of increased overhead and computational complexity; Mobile Stations (MSs) need to feed back to their assigned Base Station (BS) their local channel state information (CSI) which in turn needs to be transmitted to the Control Unit that coordinates the cooperating BSs. Furthermore user data needs to be routed to and from all cooperating BSs on the downlink and uplink respectively. Therefore in order for the overhead to be affordable, it is admitted that cooperating BSs shall be organised in clusters of a limited size. Nevertheless, it is still crucial that CSI feedback and inter-base information exchange be reduced. In this paper linear precoding is considered with the target of overhead minimisation of the downlink. A novel technique is proposed which allows MSs not to feed back the channel coefficients related to the cluster BSs that provide weak channel quality. This is shown to provide a good trade-off between performance and overhead.

OMEGA ICT project: Towards convergent Gigabit home networks

Abstract: Gigabit home networks represent a key technology to make the future Internet success a reality. The OMEGA European project aims to define and demonstrate such networks. Consumers will require networks to be simple to install, without the need of any new wire. To achieve this, gigabit radio links and wireless optics communications will provide wireless connectivity within the home and its surroundings. Power-line communications potentially combined with robust RF will provides a home backbone ldquowithout new wires.rdquo To make this network ubiquitous, seamless and robust a technology-independent MAC layer will ensure its global control and provide connectivities to any number of devices the user wishes to connect to it in any room in a house or a flat. In order to make this vision come true, substantial progress is required in the fields of optical-wireless and RF physical layers, in protocol design, and in systems architectures.

Synchronous ethernet: a method to transport synchronization

Abstract: This article discusses the evolving transport architecture, covering some of the synchronization distribution problems to many endpoints where mobile backhaul and TDM emulation occur. It shows how synchronous Ethernet fits into both the Ethernet and synchronization architectures, and discusses how this helped development in standardization bodies. Standardization allows the key building blocks of Ethernet silicon and specific timing devices to be developed, which allows a robust system implementation to be constructed while allowing interworking with and migration from existing SONET/SDH-based transport infrastructure. Finally, results are shown that indicate a very high level of performance is achievable with Synchronous Ethernet not subject to the normal packet delay variation and traffic load conditions that can occur in packet based networks.

Enhancing GMPLS Signaling Protocol for Encompassing Quality of Transmission (QoT) in All-Optical Networks

Abstract: In this paper, quality of transmission (QoT)-aware lightpath provisioning schemes for transparent optical networks are proposed and assessed. The main idea is to overcome lightpath blocking due to excessive physical impairments (i.e., unacceptable QoT) by means of successive lightpath set up attempts performed by generalized multiprotocol label switching (GMPLS) signaling protocol along alternate routes. The schemes are enabled by the introduction into current GMPLS signaling protocol [i.e., resource reservation protocol with traffic engineering (RSVP-TE)] of extensions which encompass the QoT parameters that characterize the optical layer. Differently from previous approaches, the proposed GMPLS-based schemes are still distributed but they do not imply the introduction of additional extensions into the routing protocol (e.g., OSPF-TE). The QoT-aware provisioning schemes are first validated by simulations performed on a WDM mesh network. Results show that only few successive set up attempts are required to complete the lightpath establishment. In addition, an experimental demonstration where the proposed RSVP-TE extensions are implemented in the control plane of a transparent metro network is reported showing that impairment-aware lightpath provisioning is achieved on a time scale of few milliseconds.