Method of transmitting signals via RF link using non-orthogonal multiple access for transmitting signals via satellites.

Abstract

A method for transmitting signals via RF link using non-orthogonal multiple access for satellite signal transmission. A method for transmitting signals via RF link using NOMA for satellite signal transmission, in a communication system comprising a transmitter (E), a satellite (SAT), and at least two heterogeneous receivers (R1, R2, R3), forming at least two sets of receivers, named the favored set and the disadvantaged set, in which: when the signal-to-noise ratio (SNR) of a receiver (R1, R2, R3) of the communication system is greater than a first threshold (S1), the receiver (R1, R2, R3) is assigned to the favored set, and otherwise it is assigned to the disadvantaged set, and a primary symbol and a secondary symbol are superimposed on the signal transmitted by the transmitter during the same symbol time, the primary symbol being intended for both the favored and disadvantaged sets.and the secondary symbol being intended for the favored set and configured to be demodulable by the favored set, but indemodulable by the disadvantaged set. Figure for the abbreviation: Figure 1,

Description

Title of the invention: Method for transmitting signals via RF link using non-orthogonal multiple access for satellite signal transmission

[0001] The present invention relates to a method of transmitting signals by RF link by non-orthogonal multiple access for transmitting signals by satellites.

[0002] Document EP3672105 B1, which discloses a non-orthogonal multiple access method for satellite transmission, is known. This document discloses that NOMA (Non-Orthogonal Multiple Access) is a network access technique derived from 5G standards and used in the context of the Internet of Things, which is described, for example, in Anas Benjebbour, "An overview of Non-Orthogonal Multiple Access," dated June 6, 2017. This document mentions that the NOMA network access technique aims to increase the spectral efficiency of a terrestrial communications network by multiplexing user pairs in the power plane. The proper reception of each of these signals requires the implementation, on the receiver side, of a source separation algorithm known as the SIC algorithm (Successive Interference Cancellation).To this end, a resource planner (or "scheduler") identifies pairs of users whose transmissions can be power-multiplexed, and assigns sufficiently different transmission power levels to the equipment constituting these pairs so that a receiver can separate the signals transmitted by each piece of equipment. At the receiver, a signal separation process is implemented to separate the signals.

[0003] This document discloses a method of non-orthogonal multiple access RF link signal transmission for transmitting signals by satellite or NOMA from a plurality of transmitters to a single receiver, wherein a symbol superposition with a power delta is performed in the transmission channel.

[0004] Also, this document does not allow the transmission of signals from a transmitter to several receivers via a satellite, by separating the receivers into two categories of receivers.

[0005] One object of the invention is to be able to overcome the problems mentioned above, and to increase the flow rates for all types of receivers.

[0006] According to one aspect of the invention, a method for transmitting signals via RF link using non-orthogonal multiple access for transmitting signals via satellites is proposed, in a communication system comprising a transmitter, a satellite, and at least two heterogeneous receptors, forming at least two sets of receptors, named the favored set and the disfavored set,

[0007] wherein when the signal-to-noise ratio of a receiver in the communication system is greater than a first threshold, the receiver is assigned to the favored set, and otherwise it is assigned to the disfavored set; and

[0008] in which, superimposed on the emission of the signal by the transmitter, during the same time symbol, is a primary symbol and a secondary symbol, the primary symbol being intended for the favored set and the disadvantaged set, and the secondary symbol being intended for the favored set and configured to be demodulable by the favored set, but indemodulable by the disadvantaged set.

[0009] According to one embodiment, the favored set includes encryption keys unknown to the disadvantaged set, allowing the decryption of the secondary symbol, and the disadvantaged set includes encryption keys known to the favored set, allowing the decryption of the primary symbol.

[0010] According to one embodiment, a tertiary symbol is superimposed, in addition, during the same symbol time, on the primary and secondary symbols, the tertiary symbol being intended for a highly favored set comprising at least one receiver of the communication system and configured to be demodulable by the highly favored set but indemodulable by the favored and disadvantaged sets,

[0011] in which, when the signal-to-noise ratio of a receiver in the communication system is greater than a second threshold that is greater than the first threshold, the receiver is assigned to the highly favored set.

[0012] In one embodiment, the highly favored set includes encryption keys unknown to the favored and disadvantaged sets, allowing the decryption of the tertiary symbol, and including the encryption keys known to the favored and disadvantaged sets.

[0013] According to an implementation mode, in which the assemblies are dynamically modifiable, based on signal-to-noise ratio measurements of the receivers.

[0014] The invention will be better understood upon examination of some embodiments described by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0015] [Fig-1] schematically illustrates the method of signal transmission by RF link by non-orthogonal multiple access NOMA for transmission of signals by satellites, in a communication system, according to the state of the art;

[0016] [Fig.2] schematically illustrates the superposition, at emission, by the emitter, of the signal, during the same time symbol, according to one aspect of the invention;

[0017] [Fig.3] schematically illustrates the case of [Fig.2] for a TRANSEC application, according to one aspect of the invention;

[0018] [Fig.4] schematically illustrates a table of modulation possibilities for the primary symbol SP and secondary symbol SS, according to one aspect of the invention;

[0019] [Fig.5] schematically illustrates the use of a third modulation for a heterogeneous network with three groups (disadvantaged, favored and highly favored), according to one aspect of the invention;

[0020] [Fig.6] schematically illustrates the case of [Fig.5] for a TRANSEC application, according to one aspect of the invention; and

[0021] [Fig.7] schematically illustrates the use of a hidden channel, according to one aspect of the invention.

[0022] Compared to state-of-the-art methods, the present invention makes it possible to increase the data rates for all types of receivers by using the entire time frame for all receivers.

[0023] The present invention also makes it possible to meet the need for a hidden channel. The secondary symbol SS can be implemented for receivers unknown to the entire network.

[0024] Finally, this solution is compatible with existing waveforms and allows for interoperability. The idea is to keep the existing waveform with the primary symbol. A waveform can then be used on top of it for the secondary symbol SS.

[0025] Fig. 1 represents the method of transmitting a signal by RF link by non-orthogonal multiple access NOMA for transmitting signals by satellites, in a communication system.

[0026] The communication system includes a transmitter E transmitting signals via an uplink LM to a satellite S AT, which broadcasts it and it is received by, in this case three receivers, a first receiver RI, a second receiver R2 and a third receiver R3, via three respective downlinks LDI, LD2 and LD3.

[0027] In the example of [Fig. 1], the downlink L1 between the SAT satellite and the first receiver RI has a poor signal-to-noise ratio (SNR), or, in other words, a signal-to-noise ratio (SNR) less than or equal to a first threshold (SI). The two downlinks L2 and L3, between the SAT satellite and, respectively, the second receiver R2 and the third receiver R3, have a good signal-to-noise ratio (SNR), or, in other words, signal-to-noise ratios (SNR) greater than the first threshold (SL).

[0028] Thus, comparison with the first threshold SI of the signal-to-noise ratio makes it possible to assign a receiver to a favored or disfavored set. In this case, the first receiver RI is disfavored and the two receivers R2 and R3 are favored.

[0029] Figure 2 schematically represents the superposition, at the transmitter's emission, of the signal, during the same time symbol, of a primary symbol SP and a secondary symbol SS, the primary symbol SP being intended for the entire favoured and the disfavored set, and the secondary symbol SS being intended for the favoured set and configured to be demodulable by the favoured set, but indemodulable by the disfavored set.

[0030] As shown in [Fig.3] in the case of a TRANSEC application, the favored set includes encryption keys unknown to the disadvantaged set, allowing the decryption of the secondary symbol SS, and the disadvantaged set includes encryption keys known to the favored set, allowing the decryption of the primary symbol SP.

[0031] The value A represents the amplitude of the favored symbol before encryption via Transec, and the value a is calculated from Pseudo Randomnesses provided by an AES type generation function. This value must be within the interval [0; A].

[0032] The values ​​2A+a and 2A-a therefore represent the distances to the origin of the favored symbol after encryption. The value <p est également générée via Pseudo Aléas dans un intervalle [0 ; 2ir].

[0033] Fig. 4 represents a table of modulation possibilities for the primary symbol SP and the secondary symbol SS as a function of the SNR / CN0 ratio of the transmission channels, SNR being the signal-to-noise ratio and CN0 representing the normalized SNR signal-to-noise ratio in dB.

[0034] The idea in this table is to show that: - when the SNR of the disadvantaged channel is very close to the noise (for example 0.3 dB above the noise) and the SNR of the favored channel is very close to the SNR of the disadvantaged channel (for example 0.7dB above the disadvantaged channel) a BPSK / BPSK constellation is preferred; - when the SNR of the disadvantaged channel is very close to the noise (for example 0.3 dB above the noise) and the SNR of the favored channel is relatively far from the SNR of the disadvantaged channel (for example 3dB above the disadvantaged channel) a BPSK / QPSK constellation is preferred; - when the channel SNR is far from the noise (for example, 5 dB above the noise) and the SNR of the favored channel is very close to the SNR of the disfavored channel (for example, 0.7 dB above the disfavored channel), a QPSK / BPSK constellation is preferable; and - when the channel SNR is far from the noise (for example more than 5 dB above the noise) and the SNR of the favored channel is relatively far from the SNR of the disfavored channel (for example 3dB above the disfavored channel) a QPSK / QPSK constellation is preferred.

[0035] Figure 5 schematically represents the use of a third modulation for a heterogeneous network with three groups (disadvantaged, favored and highly favored).

[0036] In other words, a tertiary symbol ST is superimposed on the primary and secondary symbols during the same symbol time. The tertiary symbol ST is intended for a highly favored set comprising at least one receiver of the communication system and is configured to be demodulable by the highly favored set but indemodulable by the favored and disadvantaged sets. When the signal-to-noise ratio of a receiver of the communication system exceeds a second threshold S2, which is higher than the first threshold SI, the receiver is assigned to the highly favored set.

[0037] As shown in [Fig. 6] in the case of a TRANSEC application, the highly favored set includes encryption keys unknown to the disadvantaged and favored sets, allowing the decryption of the tertiary symbol ST. The highly favored and favored sets include encryption keys unknown to the disadvantaged set, allowing the decryption of the secondary symbol SS. The highly favored, favored, and disadvantaged sets all include encryption keys allowing the decryption of the primary symbol SP. This is the same concept as in [Fig. 3], but with an additional layer: indices 1 refer to the favored symbol, and indices 2 refer to the highly favored symbol.

[0038] Fig. 7 represents the method of transmitting a signal by RF link by non-orthogonal multiple access NOMA for transmitting signals by satellites, in a communication system.

[0039] The communication system includes a transmitter E transmitting signals via an uplink LM to a satellite S AT, which broadcasts it and it is received by, in this case three receivers, a first receiver RI, a second receiver R2 and a third receiver R3, via three respective downlinks LDI, LD2 and LD3.

[0040] In the example of [Fig. 7], the downlink L1 between the SAT satellite and the first receiver RI has a poor signal-to-noise ratio (SNR), or, in other words, a signal-to-noise ratio (SNR) less than or equal to the first threshold SL. The downlink L2 between the SAT satellite and the second receiver R2 has a good signal-to-noise ratio (SNR), or, in other words, a signal-to-noise ratio (SNR) greater than the first threshold S1 but less than the second threshold S2. The downlink L3 between the SAT satellite and the third receiver R3 has a very good signal-to-noise ratio (SNR), or, in other words, a signal-to-noise ratio (SNR) greater than the second threshold S2.

[0041] Thus, comparisons with respect to the first threshold SI and second threshold S2 of the signal-to-noise ratio make it possible to assign a receiver to a disadvantaged, favored, or highly favored set. In this case, the first receiver RI is disadvantaged, the second receiver R2 is favored, and the third receiver R3 is highly favored. The use of the different encryption keys thus makes it possible, for example, to put in places a hidden channel on the receptors of the highly favored set, in this case the third receptor R3.

Claims

Demands

1. A method of transmitting signals by RF link by non-orthogonal multiple access for transmitting signals by satellites, in a communication system comprising a transmitter (E), a satellite (SAT), and at least two heterogeneous receivers (RI, R2, R3), forming at least two sets of receivers, named favored set and disadvantaged set, in which when the signal-to-noise ratio (SNR) of a receiver (RI, R2, R3) of the communication system is greater than a first threshold (SI) the receiver (RI, R2, R3) is assigned to the favored set, and otherwise it is assigned to the disadvantaged set;and in which, superimposed on the emission of the signal by the transmitter, during the same symbol time, are a primary symbol (SP) and a secondary symbol (SS), the primary symbol (SP) being intended for the favored set and the disadvantaged set, and the secondary symbol (SS) being intended for the favored set and configured to be demodulable by the favored set, but indemodulable by the disadvantaged set.

2. A method according to claim 1, wherein the favored set includes encryption keys unknown to the disfavored set, enabling the decryption of the secondary symbol (SS), and the disfavored set includes encryption keys known to the favored set, enabling the decryption of the primary symbol (SP).

3. A method according to claim 1 or 2, wherein a tertiary symbol (ST) is superimposed, in addition, during the same symbol time, on the primary (SP) and secondary (SS) symbols, the tertiary symbol (ST) being intended for a highly favored set comprising at least one receiver (RI, R2, R3) of the communication system and configured to be demodulable by the highly favored set, but indemodulable by the favored and unfavored sets, wherein, when the signal-to-noise ratio (SNR) of a receiver (RI, R2, R3) of the communication system is greater than a second threshold (S2) greater than the first threshold (SI), the receiver (RI, R2, R3) is assigned to the highly favored set.

4. A method according to claim 3, wherein the highly favored set comprises encryption keys unknown to the favored and disadvantaged sets, allowing the decryption of the tertiary symbol

5. (ST), and including the known encryption keys of the favored and disadvantaged sets. A method according to any one of the preceding claims, wherein the assemblies are dynamically modifiable, based on signal-to-noise ratio (SNR) measurements of the receivers (RI, R2, R3).

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