Agence Spatiale Europeenne

European Space Agency

Other

Agence Spatiale Europeene

Riccardo De Gaudenzi

Oscar Del Rio Herrero

Alberto Ginesi

Luca Fanucci

Marco Luise

Roberto Viola

Domenico Fittipaldi

Alan Bigi

Piero Angeletti

Carlo Elia

Beatrice Ponticelli

Emiliano Re

Nicolas Jeannin

Alfonso Martinez Vicente

Alfredo Vernucci

Javier Romero Garcia

Fillippo Giannetti

Enrico Casini

Edoardo Letta

Daniel Maurice Eliane Delaruelle

Jean-Pierre Georges Joseph Ghislain Choffray

Filippo Giannetti

Albert Guillen I Fabregas

This application relates to a method of performing wireless communications between a hub station and a plurality of user terminals. The method comprises transmitting radio signals to subsets of user terminals among the plurality of user terminals with sets of active beams, wherein the active beams have beam centers that are determined based on locations of the user terminals. The method further comprises, for each of a plurality of radio resource blocks: selecting a subset of user terminals among the plurality of user terminals; for each user terminal among the subset of user terminals, determining a beam center based on a location of the respective user terminal; and transmitting, using the respective radio resource block, radio signals to the user terminals among the selected subset of user terminals, in beams corresponding to the determined beam centers. The method further relates to a corresponding hub station for performing wireless communications with a plurality of user terminals, and to a method of determining antenna parameters and a beam pattern for a hub station.

Pragmatic solutions for massive MIMO for broadband telecommunication systems

A method of transmitting data packets from a terminal (T) to a gateway receiver (GWR) over a channel shared with other terminals using an unslotted spread spectrum random access protocol, characterized in that transmission is performed at a transmit power level given by the sum of a deterministic term, function of a communication link budget, and of a random term, following a predetermined probability distribution. A method of operating a communication system, based on the method of transmitting data packets. A communication system and a terminal for implementing the methods.

Transmit power control in a spread-spectrum unslotted random access communication system

A method of transmitting data packets over a transmission channel shared by transmitters on the basis of a first unit of transmission of fixed length subdivided into second units of transmission of fixed length, includes: associating, at a first transmitter, for each packet to be transmitted at least two packet replicas with respective second units within a current first unit; generating, at the first transmitter, the replicas, in each of which signaling information is included, the signaling information indicating relative positions of the other replicas of the same packet within the current first unit with respect to the given replica; setting, at the first transmitter, a start timing for beginning transmission of the current first unit independently of the other transmitters of the transmitters sharing the transmission channel; and transmitting the replicas at respective timings in accordance with their association with the respective second units within the current first unit.

Method and apparatus for transmitting data packets over a transmission channel shared by a plurality of users

A satellite communication system including a multibeam satellite for generating a plurality of feeder beams and a plurality of user beams over a region of interest, a plurality of spatially-separated gateway stations for providing feeder links to said multibeam satellite via respective feeder beams; and a control for operating said gateway stations and multibeam satellite such that: in nominal conditions, Ngateway stations exchange data with K user beams, each of the gateway stations allocating a fraction of its bandwidth to each of the user beams; and in case of fading, data are switched from faded to unfaded gateway stations, whereby none of said user terminals experiences service outage. A method of performing satellite communication using the satellite communication system, and a multibeam communication satellite payload for carrying out the method are provided.

Multibeam satellite communication system and method, and satellite payload for carrying out such a method

A first aspect of the invention is a method of transmitting data packets over a transmission channel shared by a plurality of users, based on the time and/or frequency diversity slotted Aloha technique, in which at least two replicas of each packet to be transmitted are sent over said transmission channel, wherein each replica transports signaling information enabling the other replica(s) of the same packet to be located in the time and/or frequency domain. A second aspect of the invention is a method of recovering packets in the receiver, the method exploiting said signaling information to execute an interference cancellation algorithm for recovering packets corrupted by collisions caused by access conflicts. Other aspects of the invention are a transmitter equipment and a receiver packet recovery equipment adapted to use said methods.

Method of packet mode digital communication over a transmission channel shared by a plurality of users

A method of receiving data packets asynchronously transmitted by a plurality of user terminals using a spread-spectrum medium access protocol, comprises a step of cancelling interferences between colliding packets according to an innovative 'sliding window' processing algorithm. A gateway receiver is adapted for carrying out interference cancellation using this algorithm. Asynchronous packet transmission from a user terminal is controlled by estimating a parameter indicative of the quality of information transmission through a communication channel; and inhibiting or allowing data transmission depending on a comparison between said estimated parameter and an adaptively varying threshold. A user terminal comprises transmission control means adapted for carrying out such a method. A communication system comprises a plurality of mobile user terminal communicating with a gateway through a satellite channel using an asynchronous spread-spectrum medium access protocol without closed-loop power control, wherein the user terminals and said gateway are of the kind described above.

Methods, apparatuses and system for asynchronous spread-spectrum communication

A process for providing a phase synchronization of a pilot aided carrier of an input digital signal z(k), the signal z(k) having signal fields of Lsymbol signals, namely a block of Lpilot symbol signals Zand a data field of (L&#x2212;L) data symbol signals Z, and characterized for each signal field (l) by:

Process for providing a pilot aided phase synchronization of carrier

Providing a pilot aided phase recovery of a carrier of an input digital signal Zhaving signal fields of Lsymbol signals, Lpilot symbol signals Zand (L&#x2212;L) data symbol signals Z, by for each signal field:

Process for providing a pilot aided phase recovery of a carrier

A new class of 16-ary Amplitude and Phase Shift Keying (APSK) coded modulations, called double-ring APSK modulation, based on an amplitude and phase shift keying constellation in which the locations of the digital signals to be encoded are placed on two concentric rings of equally spaced signal points. The APSK constellation parameters are optimised so as to pre-compensate the impact of non-linearities. The new modulation scheme is suited for being used with different coding schemes. It is shown that, for the same coding scheme, pre-distorted double-ring APSK modulation significantly outperforms classical 16-QAM and 16-PSK over a typical satellite channel, due to its intrinsic robustness against the high power amplifier non-linear characteristics. The proposed coded modulation scheme is shown to provide a considerable performance advantage for future satellite multi-media and broadcasting systems.

Coded digital modulation method for communication system

An adaptive signal receiver comprising at least one blind detection unit arranged to be robust to asynchronous multiple access interference (MAI). The useful signal is detected using a user signature sequence comprised of a fixed term and a complex adaptive part having a length that extends over a number of samples within a defined observation window. Provision is made for updating automatically and periodically the complex adaptive part of the signature sequence.

Low complexity adaptive interference mitigating CDMA detector

The invention relates to the recognition of a spread spectrum data signal transmitted in code division multiple access communication systems. The invention provides a receiver whose code acquisition and detection circuit includes circuitry configured for detecting the signal received by using an audio adaptive detection threshold generated locally from the output signal of the detection circuit itself. The invention is used for example, in terrestrial or satellite radio communication systems.

Growing community of inventors

The Hague, Netherlands

Riccardo De Gaudenzi