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.

Preamble-based channel estimation techniques for OFDM/OQAM over the powerline

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 guard interval, it has the advantage of a theoretical higher spectral efficiency. Furthermore, if the pulse shape is well-localized in frequency, the resulting OFDM/OQAM signal satisfies stringent spectrum requirements. 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 describe a method for perfect channel estimation in OFDM/OQAM. Then we introduce two new realistic preamble-based channel estimation methods. The performance results are obtained by considering the transmission of an OFDM/OQAM signal over a multi-path power line communication (PLC) channel model. The proposed channel estimation methods are compared to the ones obtained with CP-OFDM.

Reduction of the Peak-to-Average Power Ratio for the OFDM/OQAM Modulation

Abstract: OFDM/OQAM is now a recognized alternative to conventional OFDM for the transmission of signals over multipath fading channels. Indeed with OFDM/OQAM an appropriate pulse-shaping can be introduced to fight against time and frequency dispersion. In order to reduce the occurrence of large peak-to-power ratios (PAPR) that are inherent to multicarrier modulations, a PAPR reduction method is proposed. The proposed technique is an adaptation to OFDM/OQAM of the selective mapping (SLM) technique already used for OFDM. It is shown that, as with OFDM, the performance increases with the number of SLM codes, but is also dependent upon the length of the OFDM/OQAM pulse shape.

Dynamic distributed method for local protection of a label-switching path

Abstract: The invention relates to a method for protection of a label-switching path in an MPLS network, comprising a plurality of nodes connected by means of IP connections, said path beginning at an entry node and terminating at a network exit node, passing through a determined series of nodes and connections in the network called pathway elements. When said entry node requires the protection of a pathway element, in a first phase, a node of said pathway called PLR point, upstream of said element to be protected, determines a rescue path, called a bypass tunnel, rejoining the pathway downstream of said element for protection, at a node called PM point and, in a second phase, network resources are reserved from each connection of the bypass tunnel to ensure said pathway in case of failure of said element.