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.

A study of OFDM parameters for high data rate radio LANs

Abstract: This paper presents the technical advantages of using a multicarrier OFDM modulation for high data rate wireless LANs. It investigates a way of choosing the key parameters of a coded-OFDM (COFDM) system dedicated to such networks. As an example, the broadband radio access network called HIPERLAN/2 is studied. The comparison of two differential subcarrier modulation schemes specific to OFDM modulation, in the frequency domain and in the time domain, is more particularly detailed, through simulations and a theoretical analysis. Furthermore, considering the necessity for the system to be robust to noise as well as to frequency offset, turbo-codes are proposed. Information on FFT complexity is finally provided.

Optical fiber design for strong gratings photoimprinting with radiation mode suppression

Abstract: The performances of fiber gratings can be impaired by coupling to cladding modes, especially for applications in multiplexed systems. This coupling is due to a non-zero weighted overlap integral between the guided mode and the cladding modes. It can generate transmission losses larger than 3 dB over more than 20 nm on the blue side of the resonance wavelength and are commonly observed in high reflectivity gratings (> 50%) (see for example transmission curves of figures 2 and 7 of reference [1]). From a perturbation theory, it comes that, for a tensorial perturbation Δe of the permittivity, the coupling coefficient is proportionnai to the quantity ∬ E g Δ e E c * d S, where Eg is the guided mode field and Ec a cladding mode field. In the case of a circularly symmetrical perturbation (generally assumed in photowritten gratings), the coupling is limited to cladding modes of LP0 symmetry. The above integral can be nulled if Δe is constant over the area where the guided mode field is confined [2]. This is not usely the case of the refractive index difference associated to gratings, since the cladding is far less photorefractive than the germanium-doped core. One way to solve the problem is to obtain the same refractivity in a region of a few core diameters and to ensure a constant UV illumination intensity in the same volume. This implies to modify the dopant concentration profiles of the fiber.

Adaptive data rate TDMA/CDMA communications system

Abstract: Method and apparatus for adapting a rate of communicating data via digital user signals communicated on a communication link in a digital mobile communication system The rate of communicating data via user signals communicated on a communication link between a transmitting and a receiving station in a TDMA/CDMA digital mobile communication system is adapted by selecting at least one spreading factor and a number of time slots according to the required rate of communicating data and the receiving capabilities concerning the TDMA/CDMA feature. An appropriate number of sequences of bits of the user signal is allocated to at least one time slot. The sequences are spread individually and arranged for a burstwise transmission of a transmit signal.

La presse de consommation et le marché. Enquête sur le tiers consumériste

Abstract: Les essais comparatifs constituent sur le marche des biens de consommation un vecteur determinant dans l’ajustement entre l’offre et la demande. Apres avoir examine les differentes manieres dont, jusqu’a present, les sciences sociales ont tente de rendre compte de la production d’informations consumeristes, l’auteur analyse la construction concrete des essais comparatifs : cadrage du marche, elaboration des epreuves, fixation de criteres d’excellence, rapport avec les industriels concernes. L’auteur utilise a cette fin le travail de test et de prescription realise, dans deux grands periodiques francais, a propos de produits de telecommunication. Il apparait, au total, que les acteurs consumeristes sont loin d’etre les simples porte-parole d’une offre deja constituee. Ils contribuent a l’inverse a la mise en forme de cette offre selon des normes differentes de celles fournies au depart par les industriels.