Orange S.A.

About: Orange S.A. is a company organization based out in Paris, France. It is known for research contribution in the topics: Terminal (electronics) & Signal. The organization has 6735 authors who have published 9190 publications receiving 156440 citations. The organization is also known as: Orange SA & France Télécom.

Discovering Chronicles with Numerical Time Constraints from Alarm Logs for Monitoring Dynamic Systems

Abstract: We address the problem of knowledge acquisition for alarm correlation in a complex dynamic system like a telecommunications network. To reduce the amount of information coming from telecommunications equipment, one needs to preprocess the alarm stream and we propose here a way to acquire some knowledge to do that. The key idea is that only the frequent alarm sets are relevant for reducing the information stream: we aggregate frequent relevant information and suppress frequent noisy information. We propose algorithms for analysing alarm logs: first stage is to discover frequently occurring temporally-constrained alarm sets (called chronicles) and second stage is to filter them according to their interdependency level. We also show experimental results with an actual telecommunications ATM network.

Inter-cell scheduling in wireless data networks

Abstract: Over the past few years, the design and performance of channel-aware scheduling strategies have attracted huge interest. In the present paper we examine a somewhat different notion of scheduling, namely coordination of transmissions among base stations, which has received little attention so far. The inter-cell coordination comprises two key elements: (i) interference avoidance; and (ii) load balancing. The interference avoidance involves coordinating the activity phases of interfering base stations so as to increase transmission rates. The load balancing aims at diverting traffic from heavily-loaded cells to lightly-loaded cells. We consider a dynamic scenario where users come and go over time as governed by the arrival and completion of random data transfers, and evaluate the potential capacity gains from inter-cell coordination in terms of the maximum amount of traffic that can be supported for a given spatial traffic pattern. We also show that simple adaptive strategies achieve the maximum capacity without the need for any explicit knowledge of the traffic characteristics. Numerical experiments demonstrate that inter-cell scheduling may provide significant capacity gains, the relative contribution from interference avoidance vs. load balancing depending on the configuration and the degree of load imbalance in the network.

Sporadic frame dropping impact on quality perception

Abstract: Over the past few years there has been an increasing interest in real time video services over packet networks. When considering quality, it is essential to quantify user perception of the received sequence. Severe motion discontinuities are one of the most common degradations in video streaming. The end-user perceives a jerky motion when the discontinuities are uniformly distributed over time and an instantaneous fluidity break is perceived when the motion loss is isolated or irregularly distributed. Bit rate adaptation techniques, transmission errors in the packet networks or restitution strategy could be the origin of this perceived jerkiness. In this paper we present a psychovisual experiment performed to quantify the effect of sporadically dropped pictures on the overall perceived quality. First, the perceptual detection thresholds of generated temporal discontinuities were measured. Then, the quality function was estimated in relation to a single frame dropping for different durations. Finally, a set of tests was performed to quantify the effect of several impairments distributed over time. We have found that the detection thresholds are content, duration and motion dependent. The assessment results show how quality is impaired by a single burst of dropped frames in a 10 sec sequence. The effect of several bursts of discarded frames, irregularly distributed over the time is also discussed.