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.

Best-effort networks: modeling and performance analysis via large networks asymptotics

Abstract: We introduce a class of Markov models, termed best-effort networks, designed to capture performance indices such as mean transfer times in data networks with best-effort service. We introduce the so-called min bandwidth sharing policy as a conservative approximation to the classical max-min policy. We establish necessary and sufficient ergodicity conditions for best-effort networks under the min policy. We then resort to the mean field technique of statistical physics to analyze network performance deriving fixed point equations for the stationary distribution of large symmetrical best-effort networks. A specific instance of such networks is the star-shaped network which constitutes a plausible model of a network with an overprovisioned backbone. Numerical and analytical study of the equations allows us to state a number of qualitative conclusions on the impact of traffic parameters (link loads) and topology parameters (route lengths) on mean document transfer time.

Blind equalization in the cepstral domain for robust telephone based speech recognition

Abstract: An adaptive filter in a blind equalization scheme has recently been proposed to reduce telephone line effects for speech recognizers. The implementation of the blind equalization scheme using a circular-convolution frequency domain adaptive filter has been described in a previous paper. This paper presents a new implementation of this blind equalization scheme in the cepstral domain. The property of a constant long-term cepstrum of speech helps to compute the gradient used for adapting the weights. The performances of the spectral domain and the cepstral domain implementations are then compared. These filters prove to be efficient for the channel equalization task. Furthermore, speech recognition experiments show that the cepstral domain on-line adaptive filter outperforms the cepstral trajectories high-pass filter (on-line approach). This technique offers almost the same performance as the conventional cepstral substraction technique (off-line approach).

320 Gbit/s soliton WDM transmission over 1300 km with 100 km dispersion-compensated spans of standard fibre

Abstract: Soliton WDM transmission of four signals at 20 Gbit/s over 2000 km of standard fibre is achieved, with 100 km dispersion-compensated spans using polarisation multiplexing and pre-chirping. Single-wavelength transmission was performed over 2400 km. Without polarisation multiplexing, the transmission was limited to 1500 km.

Novel unsymmetrically substituted push–pull phthalocyanines for second-order nonlinear optics

Abstract: The γ (3 ω ; ω , ω , ω ) and γ (2 ω ; ω , ω , 0) hyperpolarizabilities of some novel unsymmetrically substituted phthalocyanines (Pcs) have been measured at λ =1.34 μm and λ =1.9 μm, respectively. The EFISH values are positive as expected from a strong orientational contribution. By using a two-level model including the ground and the Q-excited levels, the off-resonant dipolar β v (0) component of the β tensor has been evaluated. Values are quite significant and reach 46.7×10 −30 esu for the free molecule with an extended conjugated path to the NO 2 acceptor group. The molecules containing a transition metal yield similar values that increase with the sequence Co, Ni, Cu in correlation with the magnitude of the ground state dipole moment. THG susceptibilities are negative and much larger than those measured for similar symmetric compounds. This has been related to a dominant asymmetric contribution associated to the Q-band which is resonant at the second-harmonic frequency.

Multiuser Diversity - Multiplexing Tradeoff in MIMO Broadcast Channels with Limited Feedback

Abstract: We consider joint scheduling and beamforming in a broadcast channel with multiple antennas at the transmitter and a single antenna at the mobile receiver Perfect channel knowledge is assumed to be available at the receiver while the transmitter is provided with partial channel state information (CSIT) through a limited rate feedback channel Each user feeds back quantized information regarding the channel vector direction (from a codebook) and a quantized (scalar) channel quality indicator We identify the tradeoff between multiuser diversity and spatial multiplexing gain given a limited amount of feedback bits Scaling laws of the above parameters are derived in order to achieve a target rate performance Our results reveal useful design guidelines for the split of feedback bits for channel quantization and channel quality