Patent number 8750934 is assigned to Thales (Neuilly sur Seine, FR).
The following quote was obtained by the news editors from the background information supplied by the inventors: "When designing digital telecommunications systems, it is important to find a compromise between transmission reliability and transmission speed. As a function of the nature of the processed data, it may be preferable to transmit with a very low error rate but a likewise low speed for given physical resources, whereas in another case, for the same physical resources, the speed will be favored to the detriment of the error rate, that is to say of the robustness.
"Concerning telecommunications systems used to transmit data between aircraft and terrestrial stations, between satellites and aircraft, or systems allowing aircraft to communicate directly with one another, the search for the best speed/robustness compromise must therefore be taken into account.
"Telecommunications systems customarily have to send and receive a plurality of data streams, each type of stream having constraints in terms of service quality specific thereto. Moreover, the transmission channel varies in the course of time. Techniques make it possible today to adapt the way in which the digital data are transmitted as a function of the type of data, that is to say of the desired service quality, and of the state of the transmission channel. The estimated properties of the transmission channel and the result of this estimation makes it possible to choose a given mode of transmission for a given stream type while taking account of the state of said channel. A mode of transmission corresponds, for example, to the choice of a digital modulation and to the choice of a coding rate if a channel coder is used.
"Furthermore, a way of improving speed and/or reliability is to use techniques exploiting transmission diversity. Today, multi-antenna techniques are being increasingly used, whether in mobile telephony or else to install high-speed wireless Internet access points. These techniques rely on M sending antennas and N receiving antennas and make it possible to use the propagation properties not only related to spatial diversity but also related to temporal diversity by installing notably codes of spatial-temporal type, this technique also being called time-space multiplexing. These techniques are customarily designated by the acronym
"Today, the potential of multi-antenna communications for improving the performance of digital communications in terms of robustness and/or increase in speeds is not used within the context of telecommunications systems involving one or more aircraft."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "An aim of the invention is notably to alleviate the aforementioned drawbacks.
"For this purpose the subject of the invention is a system for communications between at least two telecommunications devices, at least one of these devices 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.times.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 so-called robust mode uses a scheme of Alamouti type, a second so-called 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.
"According to one embodiment, the M sending antennas and the N receiving antennas are arranged in orthogonal polarization diversity.
"According to one aspect of the invention, at least one of the telecommunications devices is onboard a pilotless aircraft.
"According to another aspect of the invention, at least one of the telecommunications devices is onboard a terrestrial control station.
"A terrestrial control station comprises, for example, at least N sub-stations, a sub-station comprising one of the N receiving antennas, said antennas being aligned according to a receiving axis such that they are spaced a distance d.sub.r apart.
"For a given sending device, the M sending antennas are, for example, aligned according to a sending axis and spaced a distance d.sub.t apart such that the following expression is complied with:
"L represents the distance between the sender and the receiving axis;
".lamda. represents the wavelength of the signals to be transmitted;
".theta. represents the angle between the receiving axis and the sending axis.
"According to one embodiment, telecommunications devices are onboard at least two aircraft, said devices allowing them to exchange critical and non-critical digital data by selecting one of the multi-antenna modes.
"According to another embodiment, the transmission of data in multi-antenna mode is activated when the aircraft are flying in formation.
"The sending and receiving devices comprise, for example, means for estimating their locations, this estimation allowing said devices to deduce the presence or the absence of an exploitable direct path between them, the robust mode being activated in the case of absence."
URL and more information on this patent, see: Lucidarme, Thierry. Multi-Antenna Communication System for Communicating between at Least Two Telecommunications Devices. U.S. Patent Number 8750934, filed
Keywords for this news article include: Thales, Telecommunications.
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