Abstract: The invention relates to transmission from a base station to a receiver, the base station comprising first radiating means arranged for transmitting according to an antenna pattern with respect to the receiver and further comprising second radiating means arranged for transmitting according to the same antenna pattern as the first radiating means with respect to the receiver, the transmissions of the first and second radiating means being time shifted by a determined duration.

Abstract: The invention relates to transmission from a base station to a receiver, the base station comprising first radiating means arranged for transmitting according to an antenna pattern with respect to the receiver and further comprising second radiating means arranged for transmitting according to the same antenna pattern as the first radiating means with respect to the receiver, the transmissions of the first and second radiating means being time shifted by a determined duration.

Abstract: A method for transmitting a signal carrying information elements over a plurality of frequency subcarriers simultaneously. The method comprises: identifying a set of at least one frequency subcarrier of the plurality particularly subjected to attenuation; and transmitting the signal simultaneously over said plurality of frequency subcarriers by assigning respective information elements to the frequency subcarriers of the plurality not belonging to said set and assigning to each frequency subcarrier of said set a respective coefficient set so that an envelope of the transmitted signal is less than an envelope of the signal that would be transmitted by assigning respective information elements to all the frequency subcarriers of the plurality.

Abstract: An antenna system includes at least one antenna and one X-Y mount, said mount being composed of at least three mechanical elements, the first element being a base, the second element being a lower box, the third element being a upper box, the antenna of the system being fixed to the upper box. The components of the antenna downlead are distributed in the various elements composing the X-Y mount, an OMT type junction included in the upper box enabling separation of the components of the downlead into two separate paths, a first path called the ascending path comprising components for amplifying and processing signals to be transmitted by the antenna, a second path called the descending path comprising components for processing and amplifying signals received by the antenna, the components associated with these paths being placed on either side of the various elements of the X-Y mount.

Abstract: A method includes controlling security in a communication system that involves a node capable of routing traffic according to one or more security algorithms with respective security levels. The node is adapted to estimate at least one safety degree relating to the node, to select at least one security algorithm of the one or more security algorithms, depending on the estimated safety degree; and to activate the at least one security algorithm.

Abstract: The invention relates to a method of estimating symbols carried by a digital signal that is received by a receiver over a communication channel (5), said symbols being multiplexed on orthogonal frequency sub-carriers. The inventive method comprises the following steps in relation to each symbol carried by the digital signal, consisting in: performing at least two transforms towards the frequency domain (8,9) on a portion of the received signal essentially corresponding to the symbol, said transforms being performed with a determined time lag (10) therebetween; estimating the parameters (r0, r1, . . . , rn, r?0, r?1, . . . , r?n) of the communication channel from pre-determined binary information contained in the digital signal; and estimating the symbol from a combination of the result of each of the transforms performed and the estimated communication channel parameters.

Abstract: A method includes controlling security in a communication system that involves a node capable of routing traffic according to one or more security algorithms with respective security levels. The node is adapted to estimate at least one safety degree relating to the node, to select at least one security algorithm of the one or more security algorithms, depending on the estimated safety degree; and to activate the at least one security algorithm.

Abstract: The invention relates to transmission from a base station to a receiver, the base station comprising first radiating means arranged for transmitting according to an antenna pattern with respect to the receiver and further comprising second radiating means arranged for transmitting according to the same antenna pattern as the first radiating means with respect to the receiver, the transmissions of the first and second radiating means being time shifted by a determined duration.

Abstract: A system is provided for communications between at least two telecommunications devices, at least one being onboard an aircraft, said devices comprising means for sending and/or receiving digital data, said data being classed in at least two categories, the first category corresponding to critical data, the second category corresponding to non-critical data. The data are sent on M antennas and received on N antennas. A matrix H of dimension M×N representative of the multi-antenna propagation channel is estimated and the data are sent according to a mode of transmission selected from among at least two multi-antenna modes. A first robust mode uses a scheme of Alamouti type, a second high-speed mode uses a scheme of BLAST type. The critical data are transmitted using the robust mode, the non-critical data being transmitted using one of the two multi-antenna modes. The high-speed mode is selected when the rank RH of the matrix H exceeds a previously chosen threshold value SR.

Abstract: The invention relates to transmission from a base station to a receiver, the base station comprising first radiating means arranged for transmitting according to an antenna pattern with respect to the receiver and further comprising second radiating means arranged for transmitting according to the same antenna pattern as the first radiating means with respect to the receiver, the transmissions of the first and second radiating means being time shifted by a determined duration.

Abstract: An onboard device for receiving a signal coming from an aircraft at a distance d from the device, said signal resulting from the combination of multiple propagation paths, one of the paths corresponding to the main echo of the transmitted signal, said device including an equalizer of processing depth T. The device includes means for estimating the distance covered by the second path, means for deducing therefrom a delay value ? associated with it, means for estimating when ? is greater than or equal to T the interfering signal associated with the main echo and for reducing the contribution of said signal to the total level of interference received. Also a system of communication between aircraft using the onboard device.

Abstract: The present invention relates to a method for establishing a secured communication session in a communication system between a user using an untrusted device and a server. According to the present invention the user first obtains an authentication algorithm and an encryption algorithm and then creates a session key. Next the user obtains a public key of the server and sends a personal identity number to the server for authentication by using the authentication algorithm, the personal identity number being encrypted by using the encryption algorithm and the public key of the server. The user also sends the session key to the server for encrypting purpose between the user and the server, the session key being encrypted by using the encryption algorithm and the public key of the server.

Abstract: A method for authenticating a first party with a second party, the first and second parties having means for communicating with each other, the first party having secret information and supporting a plurality of authentication modes for authenticating the first party with another party, using said secret information, the authentication modes of said plurality being arranged for protecting the first party's privacy with respective degrees. A degree with which the first party's privacy must be protected when authenticating the first party with the second party is negotiated between the first party and the second party. If the negotiation is successful, the first party is authenticated with the second party according to the authentication mode of said plurality having the negotiated degree of protection of the first party's privacy.

Abstract: Parameters for the propagation channels between each mobile terminal (14, 14A, 14B) and several fixed transceivers (13) are measured and a report message transmitted to a radio network controller (12), indicating at least one part of the measured parameters. The radio network controller processes the report messages. The parameters measured for each fixed transceiver are a propagation profile, including at least one propagation path associated with a reception energy and the parameters given in the report messages for at least one transceiver, comprise data on the energetic distribution in the propagation profile, taken into account by the radio network controller in processing.

Abstract: The invention relates to a method of estimating symbols carried by a digital signal that is received by a receiver over a communication channel (5), said symbols being multiplexed or orthogonal frequency sub-carriers. The inventive method comprises the following steps in relation to each symbol carried by the digital signal, consisting in: performing at least two transforms towards the frequency domain (8,9) on a portion of the received signal essentially corresponding to the symbol, said transforms being performed with a determined time lag (10) therebetween: estimating the parameters (r0, r1, . . . , rn, r?0, r?1, . . . , r?n) of the communication channel from pre-determined binary information contained in the digital signal; and estimating the symbol from a combination of the result of each of the transforms performed and the estimated communication channel parameters.

Abstract: The invention proposes a method for securing an interaction between a first node and a second node, wherein a security algorithm belonging to both a first set of security algorithms held by the first node and a second set of security algorithms held by a third node is selected to secure the interaction between the first and second nodes, the selection of said security algorithm taking account of capacities of both the first and third nodes.

Abstract: In a system comprising a broadcasting subsystem and a radiocommunication subsystem each connected to a mediation platform, said transmission being ciphered and arranged for being deciphered by using a key, the following steps are performed at the mediation platform, relatively to a user or group of users having terminals: determining one first and at least one second sets of values from said key, so that the knowledge of all the determined sets of values is required to retrieve the key; and controlling the broadcasting subsystem so that it transmits the first set of values to the user or group of users and the radiocommunication subsystem so that it transmits the at least one second set of values to the user or group of users.

Abstract: A method includes controlling security in a communication system that involves a node capable of routing traffic according to one or more security algorithms with respective security levels. The node is adapted to estimate at least one safety degree relating to the node, to select at least one security algorithm of the one or more security algorithms, depending on the estimated safety degree; and to activate the at least one security algorithm.

Abstract: A telecommunications system comprises a number of remote subnetworks, a subnetwork comprising at least one tactical radio node NRT serving as gateway between said subnetwork and a backbone network consisting of at least one airborne communication node. An NRT node communicates with the airborne communication node by converting the wave form of the signals to be transmitted outside the subnetwork being associated with it into a wave form used by the airborne communication node, said airborne communication node transmitting the duly received signal without modifying its wave form to at least one NRT node belonging to another subnetwork. A tactical radio communication node and an airborne communication node are also disclosed.

Abstract: The present invention relates to a method for securing a radio communication link establishment in a radio communication network comprising a local network and a secured network. The local network comprises at least a first terminal and a second terminal and at least the first terminal is capable of communicating with the secured network. The radio communication network implements layered protocol functions, comprising at least Layers 1, 2 and 3, the terminals being identifiable by their Layer 2 and 3 addresses. The secured network comprises a database comprising address correspondence information between Layer 2 and 3 addresses of terminals. In the method the first terminal authenticates itself with the secured network and then by using the Layer 3 address of the second terminal, obtaining the address correspondence information provided by the database and thereby determining the corresponding Layer 2 address of the second terminal.