The present invention relates to an earth station transmitter device (1) arranged for generating a signal to be transmitted to an earth station receiver device (3) of a satellite communication system. The earth station transmitter device comprises - shaping encapsulation means (5) for shaping and encapsulating downlink data traffic based on a modulation and coding decodable by an earth station receiver device, said shaping encapsulation means arranged to output downlink baseband frames, - further encapsulation means (7) arranged to receive said downlink baseband frames and to generate uplink baseband frames by segmenting said downlink baseband frames based on a modulation and coding decodable by a satellite receiver device, - encoding and modulation means (9) for converting said uplink baseband frames into an uplink transmission signal using said modulation and coding decodable by said satellite receiver device.
The present invention relates to an earth station transmitter device (1) arranged for generating a signal to be transmitted to a plurality of earth station receiver devices (3) of a satellite communication system. The earth station transmitter device comprises - a plurality of shapers (100), each arranged for shaping and encapsulating data traffic to a different subset of earth station receiver devices, so obtaining for each subset a virtual carrier outputting at a virtual carrier symbol rate a plurality of virtual carrier baseband frames, - a modulator (104) comprising a time slice selector (102) arranged for receiving and storing said virtual carriers outputted by said plurality of shapers, for selecting a stored virtual carrier baseband frame from a list of allowable virtual carriers as next frame to be multiplexed on a single stream, and for assigning to said selected virtual carrier baseband frame, from a list of allowable time slice numbers, a time slice number associated to the virtual carrier to which said selected virtual carrier baseband frame belongs, said modulator further comprising encoding and modulation means (103) to convert said single stream into symbols of a continuous physical carrier to be transmitted at a physical carrier symbol rate greater than or equal to the sum of said virtual carrier symbol rates, - a central unit (107) arranged for conveying to each shaper of said plurality its virtual carrier symbol rate and for conveying to said modulator a list of possible time slice numbers for each of said virtual carriers.
The present invention relates to an earth station transmitter device (1) arranged for generating a set of data to be transmitted to an earth station receiver device (3) of a satellite communication system, said earth station transmitter device comprising : - encoding and modulation means (10) for mapping a plurality of baseband frames, each associated with a modulation and coding type, to a plurality of frames of encoded and modulated symbols, - physical layer framing means (20) arranged for inserting in front of each frame of encoded and modulated symbols, a physical layer frame header, so obtaining a plurality of physical layer frames, - converter means (30) for converting a super-frame preamble, said super-frame preamble comprising a start of super-frame (SOSF) and a super-frame format indicator (SFFI), and said plurality of physical layer frames into a plurality of capacity units, each capacity unit having a length of 90 symbols, - super-frame generator means (40) arranged to prepend a first subset of capacity units corresponding to said super-frame preamble to a second subset of capacity units of said plurality corresponding to said plurality of physical layer frames, and to insert a pilot field of 36 super-frame pilot symbols type A in between each pair of consecutive blocks of 16 capacity units of said subsets, thereby obtaining a pilot segment, and arranged to generate a super-frame by collecting a number of said pilot segment, said number being smaller than 415.
The present invention relates to a satellite communication system arranged for consecutively illuminating a plurality of contours on earth and comprising : - a transmitter device arranged for generating a signal to be transmitted and comprising - one or more hopping framers each arranged for receiving a sequence of bits and for organizing said sequence into a hopping frame according to a hopping plan indicating an order in which said plurality of contours is to be illuminated, - encoding means per hopping framer, - modulation means per hopping framer arranged for receiving said sequence of digital symbols and for modulating said digital symbols on a waveform at a symbol rate, - a satellite comprising a beam hopping transponder arranged for receiving said modulated signal and for outputting a version of said modulated signal to an illumination circuit arranged in said satellite for steering illumination from one contour to another particular contour according to said hopping plan, - one or more receiver devices in said particular contour of said plurality of contours to be illuminated and arranged for receiving said output signal, - a central controller having an established communication link with at least one of said receiver devices and arranged for receiving via an established link information on observed illumination transitions.
A transmitter device comprises a first predistortion circuit and a second predistortion circuit having at least one correction stage provided with a correction path for determining a correction term. The correction term for each source signal is a function of a corresponding symbol of a predefined constellation for each source signal and of the output of a model having a circuit to emulate modulation means and the second predistortion circuit, a circuit to emulate a non-linear transmission link over which a predistorted version of an aggregate pulse-shaped signal is to be transmitted for amplitude levels before saturation of an AM/AM characteristic of the transmission link occurs and to emulate the non-linear transmission link for amplitude levels beyond saturation of the AM/AM characteristic, and a circuit to emulate demodulation means.
The present invention relates to a transmitter device arranged for receiving one or more 5 source signals, each containing a sequence of source data symbols. The transmitter device comprises a first predistortion circuit and a second predistortion circuit. The first predistortion circuit comprises at least one correction stage provided with a correction path for determining a correction term. The correction term for each source signal is a function of a corresponding symbol of a predefined constellation for each source signal 10 and of the output of a model. This model comprises a circuit to emulate modulation means and the second predistortion circuit, a circuit to emulate a non-linear transmission link over which a predistorted version of an aggregate pulse-shaped signal is to be transmitted for amplitude levels before saturation of an AM/AM characteristic of the transmission link occurs and to emulate the non-linear transmission link for amplitude levels beyond saturation of the 15 AM/AM characteristic and a circuit to emulate demodulation means. The first predistortion circuit is arranged for adding, for each source signal, the correction term to a digital symbol applied to the first predistortion circuit or to a digital symbol output by a preceding correction stage of the first predistortion circuit.
A receiver device for a communication system is arranged for receiving a signal comprising a plurality of transponder signals each containing a plurality of carrier signals and comprises: an adjustable spectral filter configurable for selecting a desired transponder signal. Means for performing a non-linear transformation on the selected desired transponder signal, whereby the non-linear transformation is represented by a set of parameter values. At least one receive filter configurable to select at least one desired carrier signal of the non-linearly transformed selected desired transponder signal and, performance measuring means for determining one or more performance metrics on at least one carrier signal of the plurality of carrier signals contained in the desired transponder signal to obtain the set of parameter values.
H04J 3/17 - Systèmes multiplex à division de temps dans lesquels le canal de transmission attribué à un premier utilisateur peut être repris et assigné à un second utilisateur si le premier devient non actif, p. ex. TASI
H04B 1/10 - Dispositifs associés au récepteur pour limiter ou supprimer le bruit et les interférences
H04B 1/12 - Montages de neutralisation, d'équilibrage ou de compensation
A predistortion circuit for countering interference affecting a digital signal during transmission over a transmission link comprises a path of the digital signal between a mapper at a transmitter side and a demapper at a receiver side. The predistortion circuit is arranged for receiving a version of a digital symbol selected from a predefined constellation used for mapping a bit stream, and includes at least one correction stage provided with a correction path arranged for determining a correction term as a function of the output of a model equivalent to the transmission link and a corresponding symbol of a target constellation. The position of the target constellation points is determined using a measure accounting for the transmission link. The predistortion circuit is arranged for adding the correction term to the received version of the digital symbol and outputting the result of adding as an updated version of the digital symbol.
The present invention relates to a receiver device for a communication system. The receiver device is arranged for receiving a signal comprising a plurality of transponder signals each containing a plurality of carrier signals and comprises : - an adjustable spectral filter (262) configurable for selecting a desired transponder signal (270), - means (263) for performing a non-linear transformation on the selected desired transponder signal, whereby the non-linear transformation is represented by a set of parameter values, - at least one receive filter (264) configurable to select at least one desired carrier signal of the non- linearly transformed selected desired transponder signal, - performance measuring means for determining one or more performance metrics on at least one carrier signal of the plurality of carrier signals contained in the desired transponder signal to obtain the set of parameter values.
A device for predistortion and pulse shaping filtering in a communication system includes input scaling means arranged for scaling an applied transmit symbol with an adaptable input gain scaling factor, and a pulse shaping filter and a predistortion unit arranged for applying on the input gain scaled transmit symbol in either order a filtering operation and a non-linear predistortion operation to obtain a predistorted signal. The non-linear predistortion operation is represented by a set of parameter values selectable among a plurality of given sets of parameter values. The predistortion unit is arranged for selecting the set of parameter values exploiting a given performance measure. The device includes output scaling means arranged for scaling the predistorted signal with an output gain scaling factor to obtain a transmit signal. The adaptable input gain scaling factor and the output gain scaling factor are precalculated values corresponding to the selected set of parameter values.
H04L 25/49 - Circuits d'émissionCircuits de réception à conversion de code au transmetteurCircuits d'émissionCircuits de réception à pré-distorsionCircuits d'émissionCircuits de réception à insertion d'intervalles morts pour obtenir un spectre de fréquence désiréCircuits d'émissionCircuits de réception à au moins trois niveaux d'amplitude
The present invention is related to a device for generating waveguide modes for use in a feed horn of a satellite antenna system, said waveguide modes comprising at least one excitation mode of higher order than the fundamental mode, said device comprising a waveguide containing a first waveguide section with at least three longitudinal slots extending in the inner side of said waveguide, characterized in that said waveguide contains a second waveguide section with at least three longitudinal slots extending in said inner side of said waveguide.
H01P 1/16 - Sélecteurs de mode, p. ex. pour empêcher ou favoriser la propagation suivant un mode donnéConvertisseurs de mode
H01P 3/123 - Guides d'ondes creux présentant une section complexe ou en forme d'échelons, p. ex. guides d'ondes striés ou rainurés
H01P 3/02 - Guides d'ondesLignes de transmission du type guide d'ondes à deux conducteurs longitudinaux
H01Q 19/13 - Combinaisons d'éléments actifs primaires d'antennes avec des dispositifs secondaires, p. ex. avec des dispositifs quasi optiques, pour donner à une antenne une caractéristique directionnelle désirée utilisant des surfaces réfléchissantes où les surfaces sont concaves la source rayonnante primaire étant un élément rayonnant unique, p. ex. un dipôle, une fente, une terminaison de guide d'onde
H04B 14/00 - Systèmes de transmission non caractérisés par le milieu utilisé pour la transmission
12.
MODULATION WITH AN APSK CONSTELLATION HAVING ONE RING WITH UNEQUALLY SPACED POINTS
The present invention relates to a method of digital modulation comprising: generating a stream of modulation symbols in order to produce a modulated signal, where said modulation symbols belong to a multi- ring digital signal constellation (200, 201, 202, 203), said multi-ring digital signal constellation having all signal points placed on at least two concentric rings (200, 201, 202, 203), whereby • a) the total number of signal points is larger than 8, • b) at least one ring has unequally spaced points (201), and • c) said at least one ring with unequally spaced signal points is constructed to form together with at least one neighbouring ring a subset of neighbouring rings (202), whereby each signal point of said subset has a unique angular coordinate modulo 2 π and whereby the angular spacing of the signal points of said subset is uniform (Δ θ).
The present invention relates to a receiver for a digital communication system comprising - a demodulator arranged for receiving a quadrature amplitude modulated stream of digital symbols and for outputting a sequence of demodulated digital symbols, - a bit demapper arranged for being fed with the sequence of demodulated symbols and for determining a three-bit representation for the demodulated symbols associated with points of a predefined constellation, said three-bit representation being a set of probability values for each bit position, said predefined constellation having a first and second point of different amplitude and zero reference phase, a third point having an amplitude equal to the amplitude of the first point and a 180 degree reference phase, a fourth point having an amplitude equal to the amplitude of the second point and a 180 degree reference phase, and - a decoder arranged for receiving the set of probability values and for determining values for each bit, characterised by said predefined constellation further having a fifth and a sixth point having real magnitudes substantially larger than the amplitude of the first point and equal imaginary magnitudes of opposite sign, and seventh and eighth points having substantially equal to a negation of the amplitude of the fifth and sixth points and equal imaginary magnitudes of opposite sign. The present invention relates to transmitter and a receiver for a digital communication system, the transmitter comprising: • - an encoder for encoding a sequence of information bits and for outputting a sequence of coded bits, • - a bit mapper arranged for being fed with said sequence of coded bits and for mapping said coded bits three-by-three to digital symbols, said digital symbols being a point of a predefined quadrature amplitude modulation constellation, said constellation having a first (B) and second point (H) of different amplitude and zero reference phase, a third point (A) having an amplitude equal to the amplitude of said first point and a 180 degree reference phase, a fourth point (G) having an amplitude equal to the amplitude of said second point and a 180 degree reference phase, • - a modulator arranged for receiving said sequence of said digital symbols and for applying a linear modulation to said sequence of said digital symbols, so that a transmit waveform is obtained, characterised by said predefined con said predefined constellation further having a fifth (D) and a sixth point (F) having real magnitudes larger than the real amplitude of said first point and equal imaginary magnitudes of opposite sign, and seventh (C) and eighth (E) points having real values equal to a negation of the real amplitude of said fifth and sixth points and equal imaginary magnitudes of opposite sign.
H04L 27/34 - Systèmes à courant porteur à modulation de phase et d'amplitude, p. ex. en quadrature d'amplitude
H04L 1/00 - Dispositions pour détecter ou empêcher les erreurs dans l'information reçue
14.
SIGNAL PREDISTORTION BY ADDITION OF A CORRECTION TERM DEPENDING ON A PREDEFINED CONSTELLATION SYMBOL, A TRANSMISSION MODEL AND A TARGET CONSTELLATION SYMBOL
The present application relates to a predistortion circuit (1) for countering non-linear interference affecting a digital signal during transmission over a transmission link between a mapper at a transmitter side and a demapper at a receiver side, wherein the predistortion circuit is arranged for receiving a digital symbol selected from a predefined constellation used for mapping a bit stream, and comprises: one correction stage (2) arranged for: - determining the output value (5) of a transmission link model receiving the digital symbol as input; - determining a correction term (4) as a function of said output value (5) and a target constellation symbol; and one adder arranged for adding said correction term (4) to the digital symbol and for outputting the result of said adding as an updated version of the digital symbol, wherein: the target constellation is derived from said predetermined constellation and said transmission link model, and the target constellation symbol is the symbol of the target constellation corresponding to said digital symbol.
The present invention is related to a device for generating waveguide modes for use in a feed horn of a satellite antenna system, said waveguide modes comprising at least one excitation mode of higher order than the fundamental mode, said device comprising a waveguide containing a first waveguide section with at least three longitudinal slots extending in the inner side of said waveguide, characterised in that said waveguide contains a second waveguide section with at least three longitudinal slots extending in said inner side of said waveguide.
A wireless multiple access communication system (5) comprises a forward link (31) to a terminal (40) and a return link (32) from a terminal (40). The return link (32) uses a medium which is shared between terminals (40) on the basis of time and frequency. A terminal (40) transmits a return link signal (32) from the terminal comprising a sequence of transmission slots (51, 52, 53), each transmission slot being defined as a time slot and, carrier frequency, wherein carrier frequency and symbol rate can change between transmission slots. The return link signal (32) is transmitted continuously across the sequence of transmission slots (51, 52, 53). The terminal can transmit a return link signal (32) which is phase continuous across the transmission slots.
An FDM-CPM multi-user detector (30) jointly detects the received symbols for all users by determining from the received multi-user signal an a-posteriori probability mass function (pmf) of a time-sequence of states and transmitted symbols of all users, by iterative message passing corresponding to a specific factorisation of the pmf. The factorisation involves a combined variable representing possible transmitted symbols and CPM states of each user for each symbol time interval, so as to make the iterative process convergent. Non exponential complexity is enabled by disregarding multiple access interference (MAI) from at least some of the other users. Applications can include hubs for satellite communication ground stations.
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