Full-duplex communication method and associated wireless communication device

Abstract

Full-duplex communication method and associated wireless communication device. The invention relates to a full-duplex communication method implemented by a wireless communication device (10) comprising a set of receiving antenna elements and a set of transmitting antenna elements, the method comprising: the transmission, by at least one transmitting antenna element, of a first signal intended for at least one wireless receiving device (20, 30); and the transmission, by at least one transmitting antenna element, of a second signal directed towards at least one of the receiving antenna elements, the second signal intended to reduce the power level received by the receiving antenna elements following the transmission of the first signal. Figure for the abstract: Fig. 1.

Description

Title of the invention: Full-duplex communication method and associated wireless communication device Technical field

[0001] The present invention belongs to the general field of telecommunications, and in particular wireless communications implemented on radio-type networks such as mobile networks (e.g. 3G, 4G, 5G, B5G etc.), Wi-Fi, etc. It relates more particularly to a full-duplex communication method. It also relates to a wireless communication device comprising an array of antenna elements, said device having an architecture configured to transmit and receive beams via said antenna elements.

[0002] The invention finds a particularly advantageous, although in no way limiting, application in the case of a wireless communication device of the MIMO type (acronym for the English expression "Multiple Input Multiple Output") using several antennas for transmission and reception, and in particular in the case of a wireless communication device of the massive MIMO type relying on a large number of antennas (typically from 16 to 128 antennas, this number being likely to increase in the future). Prior art

[0003] In order to adapt to the continuous and ever-increasing growth of data traffic emitted by wireless communications systems, different technologies are currently being implemented and are still being improved with a view to optimal exploitation in the years to come.

[0004] Among these technologies, and more particularly in the context of MIMO type wireless communications systems, it is known to configure a wireless communications device, such as for example a base station or a mobile telephone, with the aim of simultaneously transmitting and receiving several data streams via an antenna network (i.e. a set of antenna elements or elementary antennas) equipping said wireless communications device. This is referred to as "full-duplex" type communication when data are transmitted and received simultaneously, and more specifically as "in band full-duplex" type communication when data are transmitted and received simultaneously using the same frequency band. Advantageously, these data streams are carried by directional transmission beams (also called "beamforming" in the English literature) formed for this purpose.The use of such beams thus allows the wireless communication device to deliver or receive data with a . high spectral efficiency as well as high throughput.

[0005] "Full-duplex" type communications are notably implemented within the framework of "Integrated Access and Backhaul" (IAB) architectures, which offer a connection between a user terminal (UE) and a base station ("IAB-donor") connected to the core network via an intermediate base station ("IAB-node") acting as a relay between the user terminal and the base station connected to the core network.

[0006] However, the main challenge of "full-duplex" communications is self-interference, which is caused by the coupling of the transmitting antenna elements with the receiving antenna elements. Indeed, since the reception and transmission of signals are implemented simultaneously (and this, using the same frequency band), a signal for example transmitted by a first base station to a second base station will inevitably be received by the receiving antenna elements of the first base station, while this first base station would only wish to receive signals from other devices. This signal received when it was not desired is generally called "self-interference signal" (SI).

[0007] This is all the more true in the context of the 5G standard (fifth generation of the mobile telephony standard) where the attenuation in free space is significant, and where the signal of interest (eg, coming from another device) is of much lower amplitude than the amplitude of the self-interference signal.

[0008] Various interference cancellation methods have been developed. Some aim to improve the isolation between the receiving antenna elements and the transmitting antenna elements in a topological manner. Others operate at the analog (RF or baseband) or digital level by copying a portion of the transmitted signal and then subtracting it on the receiving path in order to eliminate the self-interference signal.

[0009] However, these methods cancel the self-interference signal by passing into the analog and / or time domain. However, cancellation in the analog domain can suffer from constraints and imperfections related to the analog components, and cancellation in the time domain suffers from a high sensitivity to synchronization. Indeed, the slightest difference between the two signals can induce significant errors. Statement of the invention

[0010] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above, by proposing a solution which makes it possible to cancel a self-interference signal by exploiting the spatial domain offered by the sets of receiving and transmitting antenna elements of a wireless communication device, while remaining in the so-called modulation domain (i.e., frequency, time or other).

[0011] To this end, and according to a first aspect, the invention relates to a method of "in band full-duplex" communication (simultaneous transmission and reception using the same frequency band) implemented by a wireless communication device comprising a set of reception antenna elements and a set of transmission antenna elements, the method comprising: • a transmission, by at least one transmission antenna element, of at least one first signal intended for at least one wireless receiving device; and • an emission, by at least one (other) emission antenna element, of a second signal directed towards at least one of the reception antenna elements, the second signal aiming to reduce a power level received by the reception antenna elements following the emission of the first signal.

[0012] These transmissions are implemented simultaneously. The advantages of full-duplex in-band communication lie in particular in the fact that the wireless communication device according to the invention is capable of simultaneously transmitting and receiving signals in a frequency band associated with it. Such arrangements advantageously make it possible to avoid having to use multiple frequency bands, which are rare resources, to transmit and receive signals on the one hand, thus improving the spectral efficiency of said device.

[0013] Generally speaking, those skilled in the art may refer to the following document for further details regarding the implementation of full-duplex communications: "In-Band Full-Duplex Wireless: Challenges and Opportunities", A. Sabharwal, P. Schniter, D. Guo, DW Bliss, S. Rangarajan, R. Wichman, IEEE Journal of Selected Areas in Communications, vol. 32, no. 9, pp. 1637-1652, Sept. 2014.

[0014] Thus, a communication method is proposed which, unlike conventional methods of canceling self-interference - which, after conversion, subtract a self-interference signal from a received signal - comprises the transmission of a signal (eg, the second signal) including data making it possible to reduce (or even cancel) a power level received by the receiving antenna elements of the wireless communication device, following the transmission of a first signal by this same wireless communication device.

[0015] The at least one first and second signal are transmitted by the wireless communication device in the form of directional transmission beams.

[0016] In particular embodiments, the wireless communication device is a base station, the first signal includes at least one signal intended for a user terminal and at least one other signal intended for another base station, and the communication is then called "downlink".

[0017] Generally speaking, it is considered that the steps of a method should not be interpreted as being linked to a notion of temporal succession.

[0018] In particular embodiments, the communication method may further comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations.

[0019] In particular embodiments, the wireless communication device comprises a plurality of RF chains, each RF chain is connected to at least one of said transmitting antenna elements, and one of said chains is dedicated to processing the second signal.

[0020] In particular embodiments, the wireless communication device is configured to transmit Nr signals simultaneously by a hybrid beamforming method, by implementing a digital precoding step and an analog precoding step.

[0021] In particular embodiments, the communication method further comprises: • a digital baseband precoding step to obtain NTRF stream; • for each of the NTRF streams, a step of converting said stream into an analog stream and a step of mixing and / or analog filtering of said analog stream, so as to obtain an RF data stream; • an analog precoding step of the NTRF RF data streams, so as to obtain the second signal and NT - 1 first signals directed to NT - 1 wireless receiving devices (or receivers).

[0022] In particular embodiments, the communication method further comprises a step of determining an analog precoding matrix Frf, the second signal being transmitted as a function of said analog precoding matrix Frf.

[0023] In particular embodiments, the communication method further comprises a step of determining an analog precoding matrix Frf by concatenation of NT depointing column vectors, one of said vectors being representative of a phase to be applied to a signal at the input of at least one of said transmitting antenna elements, so as to direct the second signal towards said at least one receiving antenna element.

[0024] In particular embodiments, the communication method further comprises a step of determining a baseband digital precoding FBB matrix.

[0025] In particular embodiments, the communication method further comprises a step of determining a precoding matrix F BB digital baseband by applying a zero forcing criterion, the precoding FBB matrix being defined such that:

[0026] Fbb = (H»qHeq j - [H^qAZF - n^qAZF,

[0027] with H a matrix representative of a global communication channel, Heq a ​​matrix representative of an equivalent communication channel, H a normalization factor and Azf an objective matrix of dimension (jy + N RF^ x NT, with a number of signals emitted by the wireless communication device, NRF+ > 1 a number of RF chains dedicated to the processing of the second signal, said matrix AZF corresponding to the concatenation of NRF+ zero row vector(s) of dimension 1 x NT, and a diagonal matrix of dimension NT x NT.

[0028] In particular modes of implementation, NRF+ = 1 and the objective matrix AZF is defined such that:

[0029] '0 0 ■■■ 0' 1 0 ■■■ 0 ^ZF ~ 0 1 ■■■ 0 10 ...... 1J

[0030] In particular embodiments, the communication method further comprises a step of determining a baseband digital precoding FBB matrix by applying a criterion for minimizing a mean square error, the precoding FBB matrix being defined such that:

[0031] Fbb= (H?qHeq + Àl)'lH^AZF

[0032] with Heq a ​​matrix representing an equivalent communication channel, 2 a Lagrange multiplier, AZF an objective matrix of dimension Nt + Nrf+ x with NT a number of signals emitted by the wireless communication device, NRF+ > 1 a number of RF chains dedicated to the processing of the second signal, said AZF matrix corresponding to the concatenation of NRF+ row vectors of dimension 1 x NT and a diagonal matrix of dimension Nt x Nt^I an identity matrix of size NT x Nr, and the adjoint matrix of a matrix M.

[0033] In particular embodiments, the second signal is represented by a spherical wave model.

[0034] The use of such a model is particularly suitable when the transmitting and receiving antenna elements are close together.

[0035] In particular embodiments, the communication channel between the same receiving antenna element and the nth transmitting antenna element is modeled as:

[0036] *-Friend

[0037] with pej'l' a complex gain representative of a communication channel between a center Op of the set of transmitting antenna elements and a center of the set of receiving antenna elements, an amplitude fluctuation with D a distance between the center Orx and the center Op , Dm>n a distance between the same element of the set of receiving antenna elements and the nth element of the set of transmitting antenna elements, X the wavelength, and ASWM — Dmn - D a phase shift between the centers Op* and Orx such that:

[0038] ASWMmn = || -â^ + Dï^ + R|| 2-D,

[0039] with - a vector from the nth transmitting antenna element to the center Opx, Du] the vector , R a rotation matrix associating a reference frame linked to the set of transmitting antenna elements to a reference frame linked to the set of receiving antenna elements, and X a vector going from the center Or , towards the same element of the set of receiving antenna elements.

[0040] In particular embodiments, the wireless communication device is a base station, the at least one wireless receiving device includes a base station, and the first signal between said base stations is modeled by a plane wave model using a direct line-of-sight communication channel.

[0041] In particular embodiments, the wireless communication device is a base station, the at least one wireless receiving device includes at least one user terminal, and the first signal between said base station and the at least one user terminal is modeled by a plane wave model using a non-line-of-sight communication channel.

[0042] In particular embodiments, the communication method further comprises a step of modeling a global communication channel including: • a communication channel between the set of transmitting antenna elements and the set of receiving antenna elements of said wireless communication device, • and a communication channel between said wireless communication device and K other devices (these other devices corresponding for example to a wireless receiving device (eg, a base station) and / or to one or more user terminals), and the overall communication channel is represented by a matrix H comprising: a first sub-matrix of dimension yK-1 o) representative of the _0 Rx TEx communication channel between the set of transmitting antenna elements of the wireless communication device and the set of receiving antenna elements of said wireless communication device, with yK-i^io) the ^=01 k number of receiving antenna elements of said communication device wireless dedicated to receiving signals from K wireless transmitting devices equipped with a set of transmitting antenna elements and the number of transmitting antenna elements of said wireless communication device 10 dedicated to transmitting signals to the K wireless receiving devices equipped with a set of transmitting antenna elements; a second sub-matrix of dimension ) x representative of the communication channel between said wireless communication device and the K other devices, with ) the number of antenna elements of said other devices used to communicate with said wireless communication device.

[0043] In particular embodiments, the K other devices include K wireless receiving devices such that K > 1, g wireless transmitting devices such that K > 1 and K ' receiving antenna elements of user terminals such that K > 1, and the communication channel between said wireless communication device and the K other devices comprises: • K communication channels between the set of antenna elements transmitting said wireless communication device and a set of receiving antenna elements of K wireless receiving devices, K communication channels between the set of receiving antenna elements of said wireless communication device and a set of transmitting antenna elements of K wireless transmitting devices, and a communication channel between the set of transmitting antenna elements of said wireless communication device and K receiving antenna elements of user terminals (UE), and said second sub-matrix comprises: a third submatrix of dimension xrepresenting channels between the set of transmitting antenna elements of said wireless communication device and sets of receiving antenna elements of each of the K wireless receiving devices, with the number of receiving antenna elements of the K devices k=0mRx,k wireless transmitters equipped with a set of transmitting antenna elements, and • a fourth sub-matrix of dimension x representing the communication channels between the set of transmitting antenna elements of said wireless communication device and the K receiving antenna elements of user terminals.

[0044] According to a second aspect, the invention relates to a full-duplex communication method implemented by a wireless communication device comprising a set of receiving antenna elements, a set of transmitting antenna elements, and a plurality of RF chains, each RF chain being connected to at least one of said transmitting antenna elements, the method comprising: • a transmission, by at least one transmission antenna element, of at least one first signal intended for at least one wireless receiving device; and • an emission, by at least one other emission antenna element, of the second signal in the form of a beam directed towards at least one of the reception antenna elements, the second signal aiming to reduce (or even cancel) a power level received by the reception antenna elements following the emission of the first signal, one of said RF chains being dedicated to processing the second signal.

[0045] In particular embodiments, the method further comprises: • reception by at least one receiving antenna element of the wireless communication device, of third signals transmitted by other devices, and of a fourth signal transmitted by said wireless communication device to at least one wireless receiving device, • hybrid beamforming including a digital post-coding step by applying a digital post-coding Wgg matrix, the method further comprising a step of determining a digital post-coding WBB matrix by applying the following constraints: • minimizing a mean square error between the first signals transmitted by the other devices and the resulting signals received by said wireless communication device (10); and, • determination of the digital post-coding WBB matrix such as the first column of a resulting WBBHeq matrix of dimension X Nj-F is a vector at least one coefficient of which is less than or equal to a predetermined threshold, with ]^FF a number of RF chains of a reception chain of the wireless communication device, ]yFF a number of chains RF of a transmission chain of the wireless communication device, Heq a ​​representative matrix of an equivalent communication channel, and the adjoint matrix of a matrix M.

[0046] According to a third aspect, the invention relates to a computer program comprising instructions for implementing a communication method according to the invention, when said program is executed by a processor.

[0047] According to a fourth aspect, the invention relates to a computer-readable information or recording medium on which the computer program according to the invention is recorded.

[0048] The information or recording medium may be any entity or device capable of storing the program. For example, the medium may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard disk.

[0049] On the other hand, the information or recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention may in particular be downloaded from a network such as the Internet.

[0050] Alternatively, the information or recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

[0051] According to a fifth aspect, the invention relates to a wireless communication device configured to communicate in full-duplex, and comprising: • a set of receiving antenna elements; • a set of transmitting antenna elements; • a transmission module configured to control a transmission of at least one first signal intended for at least one wireless reception device, the transmission module also being configured to control a transmission of a second signal directed towards at least one of the reception antenna elements, the second signal aiming to reduce a power level received by the reception antenna elements following the transmission of the first signal.

[0052] The invention is particularly advantageous insofar as the communication device according to the invention can take the form of equipment already present in the environment of a communication network. For example, it can be a base station, etc.

[0053] In particular embodiments, the wireless communication device comprises a plurality of RF chains, each RF chain is connected to a subset of at least one transmitting antenna element, and one of said chains is dedicated to processing the second signal.

[0054] According to a sixth aspect, the invention relates to a full-duplex communication method implemented by a wireless communication device, the method comprising: • reception, by at least one receiving antenna element of the wireless communication device, of first signals transmitted by other devices, and of a second signal transmitted by said wireless communication device to at least one wireless receiving device, • hybrid beamforming including a digital post-coding step by applying a digital post-coding WBB matrix, the method further comprising a step of determining a digital post-coding WBB matrix by applying the following constraints: • minimizing a mean square error between the first signals transmitted by the other devices and the resulting signals received by said wireless communication device; and, • determination of the digital post-coding WBB matrix such as the first column of a resulting WBBHeq matrix of dimension x is a vector with at least one coefficient less than a predetermined threshold, with a number of RF chains of a reception chain of the wireless communication device, a number of RF chains of a transmission chain of the wireless communication device, Heq a ​​matrix representative of an equivalent communication channel and the adjoint matrix of a matrix M.

[0055] In particular embodiments of this sixth aspect, the digital post-coding WBB matrix is ​​defined such that:

[0050] +

[0057] with AMMSE an objective matrix of dimension NR x NT, with NR a number of signals received by the wireless communication device, Nr a number of signals emitted by the wireless communication device, the matrix A^j^se C corresponding to the vertical concatenation of a non-zero column vector of dimension NR x 1, and of a diagonal matrix of dimension NR x and I an identity matrix of size 2V R x 2V Rt

[0058] In particular embodiments of this sixth aspect, the objective matrix Ammse f is defined such that:

[0059] r 1 0 ... 0' I amm se c - : : 0 ■. 0

[0060] with and r scalars depending on the coefficients of the equivalent channel matrix Heq. Brief description of the drawings

[0061] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures:

[0062] [Fig-1] [Fig.l] is an example of a communication system in which a downlink communication method is implemented;

[0063] [Fig.2] [Fig.2] is a detailed view of [Fig.l] including the communication channels communication considered in connection with a wireless communication device (10);

[0064] [Fig.3] [Fig.3] represents an exemplary implementation of a wireless communication device (10) implementing downlink communication;

[0065] [Fig.4] [Fig.4] represents an example of distribution of sets of elements receiving and transmitting antenna of a wireless communication device (10) comprising five RF chains in transmission;

[0066] [Fig.5] [Fig.5] schematically represents modules embedded in a wireless communication device (10), according to an exemplary implementation of the invention;

[0067] [Fig.6] [Fig.6] represents an example of hardware architecture of a wireless communication device (10);

[0068] [Fig.7] [Fig.7] illustrates, in the form of a flowchart, the main stages of a downlink communication method, according to an exemplary implementation of the invention;

[0069] [Fig.8] [Fig.8] is an example of a communication system in which an uplink communication method is implemented;

[0070] [Fig.9] [Fig.9] is a detailed view of [Fig.8] in which the communication channels communication considered in connection with a wireless communication device (10) are considered;

[0071] [Fig.10] [Fig.10] represents an example of implementation of a wireless communication device (10) implementing a communication method in connection rising;

[0072] [Fig. 11] [Fig. 11] illustrates, in the form of a flowchart, the main stages of a uplink communication method, according to an exemplary implementation of the invention;

[0073] [Fig. 12] [Fig. 12] illustrates the evolution of the spectral efficiency as a function of a signal-to-noise ratio, for several self-interference cancellation methods;

[0074] [Fig. 13] [Fig. 13] illustrates the evolution of the spectral efficiency when two user terminals are close to each other in azimuth and when two user terminals are far from each other in azimuth, by applying a zero forcing criterion and a criterion for minimizing a mean square error;

[0075] [Fig. 14] [Fig. 14] illustrates the evolution of the spectral efficiency as a function of a number of receiving antenna elements;

[0076] [Fig. 15] [Fig. 15] illustrates the evolution of the spectral efficiency as a function of a number of transmitting antenna elements;

[0077] [Fig. 16] Figure 16 illustrates the evolution of the received power of a signal self-interference at a frequency / — 2%GHz, as a function of tilt angle values, using a spherical wave model and a plane wave model; and

[0078] [Fig. 17] Figure 17 illustrates the evolution of the received power of a signal of self-interference at a frequency f = 2GHz, as a function of tilt angle values, using a spherical wave model and a plane wave model. Description of the embodiments

[0079] Downlink Communication

[0080] [Fig.l] is an example of a communication system in which a full-duplex and downlink communication method is implemented.

[0081] The wireless communications system is a multi-antenna or MIMO system. This system comprises a wireless transmission device 40, a wireless communication device 10 according to the invention, a wireless reception device 20, as well as a plurality of user terminals 30. A user terminal 30 corresponds for example to a laptop, a personal assistant, a connected object, a mobile telephone of the “smartphone” type.

[0082] In the present embodiment, and for the purpose of simplifying the description, it is considered that the communication system comprises only said devices 10, 20 and 40, as well as three user terminals 30.

[0083] It should however be noted that no limitation is attached to the number of communication devices 10, to the number of wireless reception devices 20, to the number of wireless transmission devices 40 or to the number of user terminals 30. The following developments can in fact be generalized without difficulty by those skilled in the art to the case where more than six devices are considered.

[0084] The wireless communication device 10 comprises a plurality N of elements antenna elements, N being an integer strictly greater than 1 organized in the form of an array of antenna elements and configured to transmit and receive beams, the latter serving as a support for the simultaneous transmission of several data streams to serve one or more determined portions of the space. It should be noted that the number of antenna elements equipping the wireless communication device 10 does not constitute a limiting factor of the invention, provided that this number is greater than 2.

[0085] Each wireless transmission device 40 and wireless reception device 20 is equipped with at least one antenna (eg, at least one antenna element). No limitation is attached to the number of antennas equipping each of said devices 40 and 20.

[0086] In the present embodiment, and for the purpose of simplifying the description, it is considered that each user terminal 30 is equipped with only one antenna, and that they do not communicate in full-duplex. It should however be noted that no limitation is attached to the number of antenna elements of the user terminals.

[0087] Thus, the communication device 10 is able to receive a signal from the wireless transmission device 40, to transmit a signal to the wireless reception device 20, and to transmit another signal to at least one user terminal 30, and this simultaneously ("full-duplex"). The devices 20 and 40 are also configured to communicate in full-duplex.

[0088] Of course, nothing excludes the possibility that the devices 20 and 40 could communicate directly with each other.

[0089] In the present embodiment, and for the purpose of simplifying the description, it is also considered that the communications between the devices 40, 10 and 20 are implemented in one direction only. However, the problem being symmetrical, the following developments can be generalized without difficulty by those skilled in the art to the case where bidirectional communications are implemented between the devices 40, 10 and 20.

[0090] The devices 10, 20, 30 and 40 belong to a wireless communications network (not shown in [Fig.l]) and are capable of communicating with each other in a frequency band associated with this wireless communications network. For the remainder of the description, it is considered in a non-limiting manner that said telecommunications network is a 5G type mobile network.

[0091] It should however be specified that the invention remains applicable to other types of telecommunications network, such as for example a GSM mobile network, 3G (the third generation of mobile telephone network standards), 4G (the fourth generation of mobile telephone network standards), 5G (the fifth generation of mobile telephone network standards) and / or B5G (acronym for "Beyond 5G"). The invention also remains applicable to a Wi-Fi network (acronym for "Wireless Fidelity"), a WiMAX network (acronym for "Worldwide Interoperability for Microwave Access"), a satellite Internet access network, etc. Generally speaking, no limitation is attached to the nature of the telecommunications network that can be considered within the scope of the present invention. Furthermore, the invention is applicable regardless of the nature of the data transiting over this network.

[0092] As illustrated by [Fig.l], the wireless transmission device 40 is a base station, for example of the "1AB-donor" type connected to the core network, the wireless communication device 10 is an intermediate base station, and the wireless reception device 20 is also an intermediate base station.

[0093] A base station is sometimes called a "nodeB" in 3G networks, "eNodeB" according to the LTE standard (acronym for "Long Terni Evolution") and "gNodeB" in 5G networks.

[0094] According to a particular implementation, the devices 10, 20 and 40 comply with the ETSI TS 123 501 standard (the current version being 17.9.0, published in July 2023 and also referenced "3GPP TS 23.501 version 17.9.0 Release 17").

[0095] It should however be noted that the invention is applicable independently of the nature of said devices 10, 20 and 40, provided that the latter are capable of carrying out wireless communications.

[0096] Thus, as mentioned previously, nothing excludes considering that the devices 10, 20 and / or 40 are access points (AP) of a local area network (Local Area Network), such as a wireless local area network, e.g., conforming to the IEEE 802.11 standards.

[0097] [Fig.2] is a detailed view of [Fig.l] including the communication channels considered in connection with the wireless communication device 10.

[0098] As previously discussed with reference to [Fig.l], the communication device 10 is configured to be able to simultaneously receive a signal from the wireless transmission device 40, transmit a signal to the wireless reception device 20, and transmit other signals to three user terminals 30.

[0099] For these reasons, the wireless transmission device 40 is represented in the form of its network of transmission antenna elements referenced 40(Tx), the wireless reception device 20 is represented in the form of its network of reception antenna elements referenced 20(Rx), and the communication device 10 is represented in the form of its network of transmission antenna elements 10(Tx) and its network of reception antenna elements 10(Rx). In order to make the model as generic as possible, in this example, it is considered that there is a tilt angle between the networks 10(Tx) and 10(Rx), so that network 10(Rx) is in direct line of sight of network 10(Tx). [O1OO] As illustrated in [Fig.2], the following communication channels are considered: • a communication channel HSf going from the network of transmitting antenna elements 10(Tx) of the communication device 10 to the network of receiving antenna elements 10(Rx) of this same communication device 10; • a backhaul Hbha^io communication channel going from the network of transmitting antenna elements 40(Tx) of the wireless transmitting device 40 to the network of receiving antenna elements 10(Rx) of the communication device 10; • a backhaul communication channel from the network of transmitting antenna elements 10(Tx) to the receiving antenna element array 20(Rx) of the wireless receiving device 20; • a Hue communication channel, from the network of transmitting antenna elements 10(Tx) to the user terminals 30.

[0101] HSI communication channel

[0102] According to a particular implementation, the communication channel Hsr is represented by a spherical wave model. The communication channel H SI between the receiving antenna element of the set 10(Rx) and the n™™ transmitting antenna element of the set 10(Tx) is then modeled such that:

[0103] — æj]'J2_ e- Aswm.^

[0104] with pe# a complex gain representative of a communication channel between a center Op of the set of transmitting antenna elements and a center Or, of the set of receiving antenna elements, AL an amplitude fluctuation with D a distance between the center Orx and the center Dp, Dm>n a distance between the mth antenna element of the set of receiving antenna elements 10(Rx) and the n™* antenna element of the set of transmitting antenna elements 10(Tx), At the wavelength, and ASWM — Dmil - D a phase shift between the centers Op and Or such that:

[0105] AsWMjnn-)| ' a7> + + R Hr^ || ? -D,

[0106] with - a vector between the nth transmitting antenna element of the set 10(Tx) and the center Or, IM the vector OT 0', R a rotation matrix associating a reference frame linked to the set of transmitting antenna elements 10(Tx) with a reference frame linked to the set of receiving antenna elements 10(Rx), and Hr^ a vector going from the center Or towards the same antenna element of the set of antenna elements of reception 10(Rx).

[0107] Backhaul communication channels

[0108] According to a particular implementation, the backhaul communications channels -^B#4O-*1() and HBH^^20 are modeled as direct line-of-sight communications channels, and the signals passing through these channels are modeled by a plane wave model.

[0109] This modeling proves to be particularly suitable when the wireless communication device 10, the wireless transmission device 40 and the wireless reception device are base stations at the top of which the antenna assemblies 40(Tx), 10(Rx), 10(Tx) and 20(Rx) are installed, since few obstacles are present at this altitude.

[0110] A communication channel is typically represented by a matrix H, and by For the sake of simplification, the channel and its matrix are identified by the same reference. The construction of the representative matrices of the backhaul channels is implemented using a ray tracing based method, so that only the pointing vectors corresponding to the transmit antenna element set and the pointing vectors corresponding to the receive antenna element set are required. The matrices Hbh4(^iq and Hbh of the backhaul channels are then defined as: 101111 C)e(C cf H BH ^=«HîhC Cf . ... . . .2 with / ^40-10 " 4^ ) and ^10-20 = ( 4^ )

[0112] with / f and ^lo^2o 'cs free space attenuation factors for the channels and respectively, ^40-^10 (respectively 0*20) the distance between devices 40 and 10 (respectively 10 and 20), of dimension x 1 the pointing vector of the set 40(Tx) of transmitting antenna elements of the wireless transmitting device 40, ¢0°) qc dimension X 1 and of dimension x 1 the pointing vectors of the sets 10(Tx) and 10(Rx) of the communication device 10, of dimension x fe pointing vector of the set 20(Rx) of the wireless receiving device 20 and f10) the azimuth and the elevation angle of the Directions of Departure (DoD) of the set of transmitting elements 10(Tx) of the communication device 10, d^ and the azimuth and the elevation angle fi# V7## Directions of Departure (DoD) of the set of transmitting elements 40(Tx) of the wireless transmitting device 40, the number of transmitting antenna elements of device D, and 'c number of receiving antenna elements of device D.

[0113] It is important to note that the expressions and above consider the particular case where the sets of antenna elements are uniform planar antenna networks ("Uniform Planar Array" according to English terminology), and where the antenna elements are regularly spaced by half a wavelength.

[0114] Furthermore, since the backhaul channels are modeled as direct line-of-sight communication channels, the DoD departure directions of the set of transmitting elements of the communication device 10 (respectively 40) are identical to the angles of arrival ("Direction of Arrivai" according to the English terminology) of the set of receiving antenna elements 20(Rx) (respectively 10(Rx)). From this construction, the dimension of the channel matrix is ​​and the dimension of the channel matrix of channel ^bhkh-20 is RH IJiH A / 20) . / 10) .

[0115] HUE, DL communication channel

[0116] In practice, the signals transmitted between a user terminal and a communication device such as a base station are frequently reflected by reflectors before reaching their target. For this, the HUE DL communication channel is modeled as a communication channel without direct line of sight. Furthermore, since the user terminals are typically at a certain distance (e.g., from a few tens of meters to around thirty kilometers) from the base station to which they are attached, the signals passing through these channels are modeled by a plane wave model.

[0117] The construction of the HuE matrix DE representative of the channel between the communication device 10 and the user terminals 30 is implemented using a method based on ray tracing. More precisely, for each user terminal, a direct beam emitted by the communication device 10 towards the given user terminal 30 is defined, then L - 1 other beams are constructed whose Direction of Departure DoD is separated by an angle of Aâ and _ both in elevation and in azimuth relative to the main beam.

[0118] To model the environment of the user terminals 30, it then follows that for each user terminal 30, L beams are emitted, and the angle of arrival DoA of these L beams is between [ - 7F, æ] for the elevation and [0, 2æ] for the azimuth.

[0119] As previously mentioned with reference to Figure 1, for the purposes of simplification of the description, it is considered that each user terminal 30 is equipped with only one antenna (eg, isotopic). Also, the number of receiving antenna elements to be considered corresponds to the number (K ​​' ) of user terminals 30 connected to the wireless communication device 10, and the channel matrix is ​​then constructed by concatenation of column vectors, each column vector representing one of the K user terminals. The uteth row of the Hue channel matrix, DL is defined as follows:

[0120] HUEtDL / ( = ^^

[0121] with L the number of paths induced by the presence of reflectors, ai the complex attenuation coefficient for the lth path, 1i the delay associated with the ;ith path, eT^ the pointing vector of the set 10(Tx) of transmitting antenna elements of the communication device 10 of dimension MTx UE ux 1 associated with the ulth user terminal, 6 / and ¢l the azimuth and elevation angles of the DoD of the i'th path. The dimension of the channel matrix is ​​then x with M^up 'c number of transmitting antenna elements of the communication device 10 dedicated to the transmission of data to the user terminals 30.

[0122] Global Channel Matrix

[0123] The global channel matrix H is then formed by a vertical concatenation of three sub-matrices: • a first sub-matrix [ 57C SI S / ] of dimension x representative of the communication channel between the set of transmitting antenna elements and the set of receiving antenna elements of said wireless communication device 10, with the number of receiving antenna elements of said wireless communication device 10 dedicated to the reception of "backhaul" signals (eg, signals transmitted by the wireless transmitting device 40) and the number of transmitting antenna elements of the wireless communication device 10; • a second sub-matrix [Hsic^bh HUEs^BH]Ae dimension M^pBB X Mp® representative of the channels between the set of transmitting antenna elements 10(Tx) of said wireless communication device 10 and the set of receiving antenna elements of the wireless receiving device 20, with the number of antenna elements of receiving the wireless receiving device 20; • a third sub-matrix ^bh-^ues Hue. dl] of dimension KX representative of the communication channels between the whole of transmitting antenna elements of said wireless communication device 10 and K antenna elements of user terminals 30, each user terminal comprising a single antenna or a plurality of antenna elements. In the latter case, the user terminal 30 is then able to exchange signals formed in the form of beams.

[0124] In other words, the first sub-matrix relates to the transmission of a self-interference cancellation (SIC) signal from the set of transmitting antenna elements 10(Tx) of the wireless communication device 10 to the set of receiving antenna elements 10(Rx) of this same device; the second sub-matrix relates to the "backhaul" signal to the wireless receiving device 20; and the third sub-matrix relates to the transmission, by antenna elements, 1 LY1 Tx,UEs of a downlink signal to K user terminals.

[0125] The global channel matrix H is then expressed as follows:

[0126] SIC SI SI H- HSIC-*BH HbH 10-*2G ^UEs-^BH Hs1C~*UE ^BH^UE HuE,DL .

[0127] It is important to note here that the contributions of the communication channel H si are included in the global channel matrix, and correspond to the first sub-matrix [S / C SI 57 ] ■ This formalization is enabled by the use of a dedicated RF chain (and transmit antenna elements connected to this dedicated RF chain), as described below.

[0128] More generally, when the communication system comprises K wireless transmitting devices 40, K wireless receiving devices 20 and K user terminals, the overall channel matrix H for a wireless communication device 10 is then defined as:

[0129] ' SIC SI ■■■ ■■■ ■■■ SI Hl-*0 H intk=lA0~*k=0 II mtk=KA,W~*k=G HintUE.lO-^laH! ^mrfc=0,](M=] ^10-»l Hintk=KA .l(rt=l HinlUE,i^k=i H- HsiC-*k=Kl H mtk^OA^k^KA Hintk=l A0^k=Kl H intk-KA AO-^k-KA H intUEA^k^KA , HsJC-*UE Hintk=0A(^UE Hintk=lA^UE H intk=KAA0^UE HüEJ)L

[0130] with H^xj-^y a notation associated with the channels with which the signals sent are not signals of interest for the corresponding receiving antennas, X the index of the RF chain of the wireless communication device 10 which is dedicated to sending its "backhaul" signal to the Xth device, and Y the index of the device which receives the signal of the Xth RF chain of the wireless communication device 10.

[0131] It is important to note here that this device Y would ideally only wish to receive the signal from the Y-th RF chain of the wireless communication device 10 but not that of the X-th RF chain of the wireless communication device 10 which therefore corresponds to an interference signal.

[0132] [Fig.3] shows an exemplary implementation of a wireless communication device (10) implementing downlink communication with user terminals.

[0133] According to the invention, the communication device 10 has an architecture configured to transmit and receive signals in full-duplex mode via antenna elements, one of the transmitted signals aiming to reduce a power level received by the reception antenna elements 10 (Rx) following the transmission of another signal, by this communication device 10 and intended for another device.

[0134] As illustrated in FIG. 3, the communication device 10 comprises a transmission chain 100(Tx) and a reception chain 100(Rx). The transmission chain 100(Tx) includes a constellation modulation block 110 implementing, for example, quadrature amplitude modulation or quadrature phase modulation. This constellation modulation block 110 is connected to a digital precoder 120. The digital precoder 120 is itself connected at the output to NTRF modulation blocks 130 implementing, for example, OFDM coding ("Orthogonal Frequency-Division Multiplexing" according to English terminology). Each modulation block 130 is connected at the output to an RF chain (acronym for "Radio Frequency") 140, of design known per se, and the NTRF RF chains are connected to an analog precoder 150 to which the transmit antenna elements 10(Tx) are connected.

[0135] This architecture offers the advantage of forming beams by a hybrid beamforming method, which is advantageous in that it offers a compromise between the high spectral efficiency offered by the use of a digital beamforming method, and the low hardware complexity and low power consumption offered by the use of an analog beamforming method.

[0136] As discussed in more detail below, one of the RF chains 140 is dedicated to processing a signal directed towards a subset of receiving antenna elements 10(Rx) and aimed at reducing a power level received by this subset of receiving antenna elements following the transmission of another signal.

[0137] The reception chain 100(Rx) includes a plurality of reception antenna elements connected to an analog post-coder 160. This post-coder is connected at output to a plurality of RF chains 170, each RF chain 170 being itself connected to a modulation block 180 implementing for example OFDM coding. This modulation block 180 is connected (directly or indirectly) to a constellation modulation block 200 implementing for example amplitude modulation in quadrature or quadrature phase modulation.

[0138] In the scenario discussed with reference to Figures 1 and 2, the only signals expected by the reception chain 100(Rx) of the communication device 10 are the signals from the wireless transmission device 20. This is the reason why a single RF chain 170 and the modulation block 180 to which it is connected are activated. And a fortiori, since only one RF chain 170 is required, it can be directly connected to the block 200, without a digital post-coder 190 being used.

[0139] Of course, a transmission chain 100(Tx) (respectively a reception chain 100(Rx)), may still include other electronic equipment (filters, etc.), this aspect not being described further here because it is outside the scope of the invention.

[0140] As represented in [Fig.3], the architecture of the RF chains is partially connected ("Partially Connected" according to the Anglo-Saxon terminology). The following developments are however adaptable without difficulty by those skilled in the art to the case where the architecture of the RF chains is fully connected ("Fully Connected" according to the Anglo-Saxon terminology).

[0141] [Fig.4] represents an example of distribution of the sets of antenna elements of receiving and transmitting a wireless communication device 10 comprising five RF chains in transmission, of the communication system of [Fig.l].

[0142] As illustrated in Figure 4, the communication device comprises a set 10(Tx) of transmitting antenna elements of dimension 10x4. This set 10(Tx) is subdivided into five subsets of dimension 2x4; • a first RX, SIC subset dedicated to the transmission of a self-interference signal (SIC) in the form of a beam directed towards a subset of reception antenna elements of said communication device 10; • a second TX sub-assembly, BH10 20 dedicated to the transmission of a signal in the form of a beam directed towards the wireless receiving device 20; • a third TX subassembly, UE30-1 dedicated to the transmission of a signal in the form of a beam directed towards a user terminal 30-1; • a fourth TX sub-assembly, UE30-2 dedicated to the transmission of a signal in the form of a beam directed towards a user terminal 30-2; and • a fifth TX sub-assembly, UE30-3 dedicated to the transmission of a signal in the form of a beam directed towards a user terminal 30-3.

[0143] Each of the five sub-assemblies is indirectly connected to an RF chain 140 of the transmission chain 100(Tx) of the communication device 10. In other words, this distribution of the set 10(Tx) of transmitting antenna elements into five sub-assemblies is enabled by the use of at least five RF chains 140. And one of these five RF chains 140 is dedicated to the transmission of a signal (SIC) aimed at reducing, or even cancel, a received power level from a self-interference (SI) signal due to another signal simultaneously transmitted by the communication device 10.

[0144] The communication device 10 further comprises a set 10(Rx) of receiving antenna elements of dimension 8x4. This set 10(Rx) is subdivided into four subsets of dimension 2x4; • a first RX sub-assembly, BH4Q 10 dedicated to receiving a signal from the wireless transmission device 40; • a second RX sub-assembly, UE30-1 dedicated to receiving a signal from a user terminal 30-1; and • a third RX sub-assembly, UE30-2 dedicated to receiving a signal from a user terminal 30-2. • a fourth RX sub-assembly, UE30-3 dedicated to receiving a signal from a user terminal 30-3.

[0145] It is important to note here that the second, third and fourth subsets are not essential in the case of a downlink, since the only expected reception signal is that of the BH40—>10 link.

[0146] [Fig.5] schematically represents modules embedded in a wireless communication device (10), according to an exemplary implementation of the invention.

[0147] The wireless communication device (10) notably comprises a transmission module MOD_TX whose functionalities are described with reference to [Fig.6].

[0148] [Fig.6] represents an example of hardware architecture of a wireless communication device (10).

[0149] As illustrated by [Fig.6], the wireless communication device 10 has the hardware architecture of a computer. Thus, the wireless communication device 10 comprises, in particular, a processor 1, a random access memory 2, a read-only memory 3 and a non-volatile memory 4. It further comprises a communication module 5.

[0150] The read-only memory 3 of the wireless communication device 10 constitutes a recording medium as proposed, readable by the processor 1 and on which is recorded a computer program PROG_DL according to the invention, comprising instructions for the execution of steps of the communication method (in downlink) as proposed below. The program PROG_DL defines one or more functional modules of the device, which rely on or control the hardware elements 1 to 5 cited above, and which notably comprise a transmission module MOD_TX configured to transmit (simultaneously): • at least one first signal intended for at least one wireless receiving device (20, 30); and • a second signal (SIC) directed towards at least one of the receiving antenna elements (10(Rx)), the second signal (SIC) aiming to reduce a level of power received by the receiving antenna elements following the transmission of the first signal.

[0151] Furthermore, the wireless communication device 10 may also comprise other modules, in particular for implementing particular modes of the full-duplex communication method, as described in more detail later.

[0152] [Fig.7] illustrates, in the form of a flowchart, the main stages of a process downlink communication, according to an exemplary implementation of the invention. This method is implemented by the wireless communication device 10.

[0153] As illustrated in [Fig.7], the downlink communication method comprises a first step S100 of configuring this wireless communication device 10, which includes the sub-steps S110 and S120.

[0154] S110

[0155] Sub-step SI 10 is a step of determining an analog precoding matrix Frf which will be used to configure the analog precoding module 150, and an equivalent RF coupler W^peC{.

[0156] By using a dedicated RF chain for processing the self-interference signal, the equation of the signals received F by all the receiving antenna elements of the communication system in the demodulation domain (frequency or time) in this downlink scenario is written as follows:

[0157] Y = wSf„HFrfFbbPX + + rSO7

[0158] with F 1T the vector representing all the y = receiving antenna elements of the communication system (including the receiving antenna elements of the wireless communication device 10), the adjoint matrix of a matrix, H the global channel matrix as defined in section “Global Channel Matrix”, FBB a digital precoding matrix, P a diagonal matrix grouping the power allocated for each transmitted signal, X the vector representing the signals transmitted by the wireless communication device 10, N the vector representing the noises received by each receiving antenna element of the set of antenna elements 10(Rx), v _[ n the vector self ~ ' •••-'] representative of the signals transmitted by the wireless transmission device 40 and representing the signals of interest to the wireless communication device 10.

[0159] It is therefore possible to "precode" and "postcode" the global channel using the matrices Frf and W^p^g. The expression of these two matrices is variable and the only constraint to be respected is that the coefficients of these two matrices are of modulus equal to 1.

[0160] According to a particular implementation, the matrix F RF results from the concatenation of NT column vectors of depointing ek, each vector being representative of a phase at applying to an input signal of at least one of said transmitting antenna elements, so as to direct the self-interference signal (SIC) towards the receiving antenna elements of the wireless communication device 10.

[0161] According to a particular implementation, when the architecture of the RF chains is partially connected, these misalignment vectors ek are defined such that:

[0162] 1 1 g-jn (sin() +sin (ük) cos (¢.)) 1 (M'v-t)siii(^)+sm(^)cos(ÿj) , gj* ( ( M$-1 ) sin (^)+( Mjr1 ) sin ( dk ) cos { ,

[0163] with a — ..--1....... a normalization factor depending on the number of PS elements transmitting or receiving antenna of the wireless communication device 10, k a direction index having a value among UE^-^ .... UE^- K ct 6k the elevation and azimuth of direction £ 'c nom^rc of rows of antenna elements of set 10(ZA.) dedicated to direction k, and jj / 'u 'c number of columns of antenna elements of set 10(ZA) dedicated to direction k, with Zx c{7\; ÆJ.

[0164] The matrix Frf is then constructed by vertical concatenation of the misalignment vectors ek which point towards the set of reception antenna elements of the wireless communication device 10 (so as to transmit the self-interference signal SIC), towards the wireless reception device 20 and towards the K user terminals connected to the wireless communication device 10.

[0165] The matrix Frf is then written as follows:

[0166] 'eSIC 0............ 0 ' 0 "■ 0 "■ : : $ eUEk=0 ...... : 0 0 ......... eT ■■ t LEk - K. -li

[0167] with esic the pointing vector associated with the dedicated RF chain of dimension \ic x X eBHi0~*20 The x-dimensional pointing vector 1 pointing to the set of receiving antenna elements of the wireless receiving device 20, eUEi the pointing vector of dimension jyjO °) x । pointing to the different directions of the K user terminals. The resulting matrix Frf is then of dimension / 10) + 1°), fxf + 2 ), with number of elements of transmitting antenna elements of the communication device 10 dedicated to the transmission of signals to the wireless receiving device 40 and to the user terminals 30, and M^xSic 'C number of transmitting antenna elements of the communication device 10 dedicated to self-interference signal transmission.

[0168] It is important to recall here that the esic pointing vector is directed towards the receiving antenna elements of the wireless communication device 10, so as to maximize the received power of this self-interference signal.

[0169] More generically, when the communication system comprises a communication device 10 and K wireless receiving devices 20, the FRF matrix is then written as follows:

[0170] >esic 0 ■ 0 0 0 I 0 ■ • 0 ■ • 0 0 ei^UEk'=0 ■ 0 . 0 0 ■ ... ^UEk"=K-\ i

[0171] The resulting Frf matrix is ​​then of dimension (1 + Æ+ k\

[0172] To obtain the matrix W the pointing vectors of the different receiving devices of the communication system are concatenated. The resulting IIRFcq matrix is then written:

[0173] RF.eq -

[0174]

[0175] with IK r an identity matrix of dimension K x K • This matrix IVRF£q is of dimension 4- x (K +K + 1)' and then 'a matrix Fbf has the same number of columns as W^p£q, this means that the number of transmitters in the communication system is the same as the number of receivers, and a hybrid beamforming method can be implemented.

[0176] The IK matrix illustrates the fact that user terminals all have a single antenna and therefore do not have the ability to perform beamforming.

[0177] Alternatively, each user terminal comprises several antennas or several RF chains and therefore has the ability to perform beamforming. In this case, the shape of the Wppeq matrix is ​​similar to that previously mentioned, but the identity matrix IF is replaced by the depointing vectors of each user terminal 30.

[0178] The equivalent channel matrix is ​​then written:

[0179] He(i = W^HF RF.

[0180] S120

[0181] The downlink communication method further comprises a step S120 of determining a baseband digital precoding FBB matrix.

[0182] Digital precoding F BB allows to act on the equivalent channel matrix Heq to bring about a desired effect. Unlike analog precoding, there are no hardware constraints that induce mathematical constraints on the expression of Fbb, and the expression of FBB is therefore determined according to a certain objective.

[0183] S120. application of a zero forcing criterion

[0184] According to a first example of implementation, the digital precoding FBB matrix in baseband is determined by applying a zero forcing criterion (ZF) in order to reduce or even cancel self-interference signals as well as interference between user terminals and the wireless communication device 10. The precoding matrix is ​​then written Fbbzf and is defined as:

[0185] PBBZF eqH eq) FI eq Az p — T]H eqAZp,

[0186] with H the matrix representing the global communication channel, Heq the matrix representing an equivalent communication channel, 1 a normalization factor such as —----!---- , an objective matrix of dimension NT + 1 x NT, with Nt the number of signals emitted by the wireless communication device 10, and the pseudo-inverse of the Moore-Penrose matrix.

[0187] The AZF matrix corresponds to the horizontal concatenation of a zero row vector of dimension 1 x NT, and a diagonal MZF matrix of dimension NT x NT. In a particular implementation, this diagonal MZF matrix is ​​an identity matrix, and the AZF matrix is ​​then expressed in the form:

[0188] '0 0 ■ ■■ 0' 1 0 ■ ■■ 0 ^ZF~ 0 1 ■ ■■ 0 .0 «■ ■ II ■■ 1.

[0189] The role of the zero line vector of dimension 1 x NT is to cancel the contribution of the signals transmitted by the transmitting antenna elements 10(Tx) and received by the receiving antenna elements 10(Rx) of this same wireless communication device 10. The role of the diagonal matrix of dimension NT x NT is to guarantee that each receiver of the communication system receives a signal without interference caused by another receiver of the communication system

[0190]

[0191] The imp a matric ■y«(l act :c 1 of the application of a forçai criterion 7 hereinafter representative of the signals 0 0 ■■■ 0 ' ;c to zero (ZF) is ■ccepts: illustrated nF(2 nUE0 ,nUEK-ï, 1U through yBH40-*10 0 ^2 ^UEO 0 ■" : o ^Pueo ■■■ : : ! \ 0 'xBW10->20' . XUEK -1 . + -r W RF + ? U £K-1, , 0 ...... UEK a, 0

[0192] The matrix Y illustrates that the application of the zero forcing criterion cancels the effect of the self-interference signal due to the signal transmitted by the wireless communication device 10 and that the receiving antenna elements of this wireless communication device 10 receive only the backhaul signal from the wireless transmission device 40, as well as noise. The application of such a ZF precoder also ensures that the receiving antenna elements 20(Rx) of the wireless reception device 20 and the K antennas of the user terminals receive only their signal of interest, without interference from other surrounding wireless reception devices or user terminals.

[0193] Alternatively, the zeros of the AZF matrix are replaced by arbitrarily small values ​​£ (e.g., g — 1O'10), in order to adapt the calculation of the matrix inversion in the Fbbzf equation so as to have a significant transmission power towards the wireless receiving devices 20 and the user terminals 30.

[0194] Alternatively, the AZF matrix is ​​adapted so as to cancel the self-interference signal and the interference of only certain transmitting parts for which it has for example been determined that they have a significant impact in terms of interference (eg, whose received power of the interference signal is greater than a predetermined threshold).

[0195] S120. application of a criterion for minimizing a mean square error

[0196] According to a second example of implementation, the precoding matrix F BB digital baseband is determined by applying a criterion of minimizing a mean square error (MMSE). The application of this criterion is illustrated through the communication system illustrated in [Fig.l], but the following developments are however generalizable without difficulty by those skilled in the art to the case where more than three user terminals 30 and / or a plurality of wireless transmitting devices 40 and wireless receiving devices 20 are considered.

[0197] Let x = [rv 1 be the vector representing the [■'■BffttFlO XUE& * • • ' xUEK-\ j signals of interest received by the different receivers (eg, the set of receiving antenna elements 20(Rx) of the wireless receiving devices 20, the K antennas user terminals, and the set of receiving antenna elements 10(Rx) of the wireless communication device 10 of the communication system.

[0198] The MMSE criterion aims to minimize the mean square error between the X and Y signals and is formalized by the following Oi equations:

[0199] (argm || P'XY || 2] Of Fbb you fS 2 1 / \ st e\ Il F BB PX II F = P(cj

[0200] with P' the diagonal matrix including the power dedicated to the emission of each signal of interest, P the total power emitted by the transmitting antenna elements 10(Tx) of the wireless communication device 10, £]] the mean square error, and || || the Frobenius norm. He reads F

[0201] These equations O) are for example solved by applying the method, well known in itself, of the Lagrange multiplier. Let 2 be a Lagrange multiplier, the expression of the matrix FBBMMSE as a function of 2 is then written: 102021 FBBi„SE = ( + AI )'h^Azf

[0203] with Heq the matrix representing the equivalent communication channel, 2 the Lagrange multiplier, XZF the objective matrix of dimension NT + 1 x NT, with NT a number of signals emitted by the wireless communication device 10, said matrix AZF corresponding to the concatenation of a zero row vector of dimension 1 x NT, and a diagonal matrix of dimension NT x NT, I the identity matrix of size Ntx Nt, and (M^ 'a adjoint matrix of the matrix M.

[0204] The resolution of the problem formalized by the equations O1 then amounts to determining a value of 2 which is determined numerically, by simulation.

[0205] S200 - S500

[0206] The downlink communication method further comprises a step S200 of digital precoding in baseband by applying the digital precoding matrix FBB (eg, Fbbzf or F bb so as to obtain a plurality of output stream of the digital precoder. This step is implemented by the digital precoder 120 of the transmission chain 100 (Tx).

[0207] Then, during a conversion step S300, each of the streams is converted into an analog stream and a step of mixing and / or analog filtering of said analog stream is implemented, so as to obtain an RF data stream. This step is implemented by an RF chain 140 of the transmission chain 100(Tx).

[0208] The communication method further comprises a step S400 of analog precoding of the RF data streams by applying the analog precoding matrix Fff, so as to obtain signals in the form of beams directed towards the wireless reception device 20 and the user terminals 30, but also a self-interference signal aimed at reducing a power level received by the reception antenna elements following the interference resulting from the transmission of the signals intended for the wireless reception device 20 and the user terminals 30. This step is implemented by the analog precoder 150 of the transmission chain 100(Tx).

[0209] Finally, the method comprises a step S500 of simultaneously transmitting the following signals in the form of beams: • a signal directed towards the wireless receiving device 20; • signals directed to each of the user terminals 30 (downlink); and, • a self-interference signal directed towards receiving antenna elements of the wireless communication device 10, this self-interference signal aiming to reduce a power level received by the receiving antenna elements following the transmission of the other signals.

[0210] Uplink communication

[0211] The invention has so far been described in the case of a downlink communication between the wireless communication device 10 and the user terminals 30. Figures 8 to 11 this time illustrate the case of an uplink communication, where the effect of self-interference is reduced or even cancelled by processing at the level of the reception chain 100(Rx) of the wireless communication device 10.

[0212] Figure 8 is an example of a communication system in which an uplink communication method is implemented. The system is similar to that illustrated in Figure 1, and is therefore not described again, for the sake of brevity. The only difference concerns the communication channel, the Hue communication channel, ul discussed with reference to [Fig.9].

[0213] Figure 9 is a detailed view of Figure 8 in which the communication channels considered in connection with the wireless communication device 10 are considered. The HSh and HB{lï(^20 channels are similar to those described in reference to [Fig.2], and are therefore not described again, for the sake of brevity.

[0214] The only difference concerns the communication channel the communication channel Hue, ul (which replaces the HUE DL channel) and which is this time directed from the user terminals 30 to the network of transmitting antenna elements 10 (Tx) of the wireless communication device 10.

[0215] HUE communication channel ul

[0216] In practice, signals transmitted between a user terminal and a communication device such as a base station are frequently reflected by reflectors before reaching their target. For this, the HUE UL communication channel is modeled as a communication channel without direct line of sight. Furthermore, since user terminals are typically at a certain distance (e.g., from a few tens of meters to about thirty kilometers) from the base station to which they are attached, the signals passing through these channels are modeled by a plane wave model.

[0217] The construction of the Hue matrix, ul representative of the channel between the user terminals and the wireless communication device 10 is implemented using a method based on ray tracing. More precisely, for each user terminal, a direct beam emitted by the given user terminal 30 towards the communication device 10 is defined, then L - 1 other beams are constructed whose Direction of Departure DoD is separated by an angle of A2 and _ both in elevation and in azimuth relative to the main beam.

[0218] To model the environment of user terminals, it then follows that L beams are emitted from each user terminal 30, and the angle of arrival DoA of these L beams at the receiving antenna elements 10(Rx) is included between [ - TF, zr] for elevation and Æ. æ] 2'21 for the azimuth.

[0219] As mentioned previously with reference to Figures 1 and 2, for the purpose of simplifying the description, it is considered that each user terminal 30 is equipped with only one antenna (eg, isotopic). Also, the number of transmitting antenna elements to be considered corresponds to the number (K) of user terminals connected to the wireless communication device 10, and the channel matrix is ​​then constructed by concatenation of column vectors, each column vector representing a transmission by one of the K user terminals. The ulth column of the channel matrix UuE, ul is defined as follows:

[0220] HUE_UUl = ( ,

[0221] with L the number of paths induced by the presence of reflectors, a< the coefficient complex attenuation for the same path, ri the delay associated with the / lèrae path, eR^ the pointing vector of the set 10(Tx) of receiving antenna elements of the communication device 10 of dimension x 1 associated with the u!th terminal user, and ( / )^ the azimuth and elevation angles of the user terminal as seen from the wireless communication device 10. The dimension of the channel matrix is ​​then x fc", with 'c the number of receiving antenna elements of the communication device 10 dedicated to receiving data from the user terminals 30.

[0222] Unlike the cancellation solution proposed for downlink communication, a dedicated RF chain for the self-interference signal is not required to cancel the uplink self-interference. Also, the matrix of global channel H of dimension + x + K") is then defined as:

[0223] H- 5Z Hbha^w SI ^UE^BH HUE, UL

[0224] [Fig. 10] shows an exemplary implementation of a wireless communication device (10) implementing an uplink communication method.

[0225] As illustrated by [Fig. 10], the communication device 10 comprises a transmission chain 100(Tx) and a reception chain 100(Rx). The transmission chain 100(Tx) includes a constellation modulation block 110 implementing, for example, quadrature amplitude modulation or quadrature phase modulation. This constellation modulation block 110 is connected (directly or indirectly) to a modulation block 130 implementing, for example, OFDM coding ("Orthogonal Frequency-Division Multiplexing" according to English terminology).

[0226] In the uplink communication scenario as illustrated by Figures 8 and 9, the only signal transmitted by the wireless communication device 10 is the backhaul signal Heh4^10. Therefore, only a single RF chain 140 needs to be activated, and a fortiori, the digital precoder 120 is deactivated.

[0227] The modulation block 130 is connected at the output to an RF chain 140, itself connected to an analog precoder 150 to which the transmission antenna elements 10(Tx) are connected.

[0228] This architecture offers the advantage of forming beams by a hybrid beamforming method, which is advantageous in that it offers a compromise between the high spectral efficiency offered by the use of a digital beamforming method, and the low hardware complexity and low power consumption. energy offered by the use of an analog beamforming method.

[0229] The reception chain 100(Rx) includes a plurality of reception antenna elements 10(Rx) connected to an analog post-coder 160. This post-coder is connected at output to a plurality of RF chains 170, each RF chain 170 being itself connected to a modulation block 180 implementing for example OFDM coding. The modulation blocks 180 are connected to a digital post-coder 190. Finally, the digital post-coder 190 is connected to a constellation modulation block 200 implementing for example quadrature amplitude modulation or quadrature phase modulation.

[0230] Of course, a transmission chain 100(Tx) (respectively a reception chain 100(Rx)), may still include other electronic equipment (filters, etc.), this aspect not being described further here because it is outside the scope of the invention.

[0231] As represented in [Fig.10], the architecture of the RF chains is partially connected ("Partially Connected" according to the Anglo-Saxon terminology). The following developments are however adaptable without difficulty by those skilled in the art to the case where the architecture of the RF chains is fully connected ("Fully Connected" according to the Anglo-Saxon terminology).

[0232] [Fig. 11] illustrates, in flowchart form, the main steps of an uplink communication method, according to an exemplary implementation of the invention. This method is implemented by the wireless communication device 10.

[0233] It is important to note here that this uplink communication method can be implemented independently of the downlink communication method previously described with reference to FIGS. 1 to 7. Alternatively, this uplink communication method is implemented in combination with the downlink communication method previously described. The uplink and downlink communication methods are then implemented simultaneously or sequentially by the wireless communication device.

[0234] As illustrated by [Fig. 11], the uplink communication method comprises a first step S1000 of configuring this wireless communication device 10, which includes sub-steps S1100 and S1200.

[0235] S1100

[0236] Sub-step SI 100 is a step of determining an analog postcoding matrix FF^ which will be used to configure the analog post-coding module 160, and an equivalent analog precoding matrix Frf^.

[0237] The equation of the signals received - by the receiving antenna elements of the device wireless communication 10 in this uplink scenario is written as

[0244] ek = a as follows:

[0238] j ^W^W^HF^x+W^W^ — W BB z

[0239] with „ _ / \T the representative vector x — \ 0-X20» xUEk"=8> " ' ' XUEk -K / signals emitted by all transmitters of the communication system, including those emitted by the transmitting antenna elements of the wireless communication device 10, P - diag( ' fêuEk^' " ' ' fêuEk"^ ) 'a matræe diagonal power representative of the power allocated to the signals emitted by each of the transmitters of the communication system, and such that:

[0240] ^W^HF^x + W^n.

[0241] It is important to note here that the contribution of the HSI communication channel is included in the global matrix H, and that the interference signal xbhi0^20 is included in the vector x. This is the reason why the dimension of the vector x is K + 2 X 1-

[0242] According to a particular implementation, the matrix results from the concatenation of depointing column vectors, each vector being representative of a phase to be applied to a signal at the input of at least one of said receiving antenna elements.

[0243] According to a particular implementation, when the architecture of the RF chains is partially connected, these misalignment vectors ek are defined such that: 1 ç-jn ( s in ( ) +sin ( ^ ) cos ( ) eJ" ( ( mev -1 ) sin ( ) +sin ( ) cos ( ) ) , - ! )sin( )+(M / r1 ) sin( 0A) cos( ,

[0245] with a — —!— a normalization factor depending on the number of elements of transmitting or receiving antenna of the wireless communication device 10, k a direction index having a value among {UEk_0, UE^ K" and dk the elevation and azimuth of the direction M^y 'c number of rows of antenna elements of the set 10(ZA.) dedicated to the direction k, and Ie number of columns of antenna elements of the set IO(Zj dedicated to the direction k, with Zx ei{Tx - RJ.

[0246] The matrix W Rr is then constructed by vertical concatenation of the vectors of de pointing which point towards the set of transmitting antenna elements of the wireless transmitting device 40, and towards the directions of each of the K user terminals connected to the wireless communication device 10.

[0247] The WRF matrix is ​​then written as follows:

[0248] wRF= eBH 4(W0 0 eUEk"=4) 0...: 0 eUEk=K-ï.

[0249] with eBH4O-»io the pointing vector of dimension X 1 pointing to the direction of the set of antenna elements in transmission of the transmitting device wireless 40' euEfc the pointing vector of dimension . x [ pointing to the JRX,UEA different directions of the K user terminals. The resulting matrix is then of dimension x ( K + ' with 'c number of antenna elements of reception of the communication device 10.

[0250] The equivalent analog precoding matrix FRp_eci is then obtained by conca tenation of the pointing vectors of the different transmitters of the communication system. The resulting matrix Frf^ is then written:

[0251] Frf^ - 0 0 eBHÏ0^20 0 ■ 0 t, , “V.

[0252] with an identity matrix of dimension K x K" ■

[0253] It is important to note here that the matrix Frf^ includes a column relating to the transmission of the interference signal %#jno-*2O previously mentioned.

[0254] S1200

[0255] The uplink communication method further comprises a step S1200 for determining a VFBB matrix for digital baseband post-coding. The problem to be solved is expressed by the following Oï equations:

[0256] / \ argminj PX - ^BB \ / Oi . st j T k W H BS H eq a = o (<:>.,). VÀ: e{0, Vl e{0, ...,K + K +K

[0257] with J a cost matrix chosen according to the desired objective, jk =

[0258]

[0259]

[0260]

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267]

[0268] (O, ... 1, O)7 The 4 x 1 dimension vector comprising only one "1" at position k and "0" elsewhere, and q (q | the dimension vector {K + K + K ) X 1 with only a "1" at the / position and "0"s elsewhere. By construction, the meaning of the constraint (¾) is explained as follows: the coefficient located at the row and at the fth column of the resulting matrix W^Heq must be equal to "0", so that the effect of the equivalent channel of the ith transmitter on the kth receiver is completely canceled. Alternatively, this coefficient must not be equal to "0", but equal to a predetermined value. It therefore follows that it is sufficient to determine the coefficients k and / to cancel the effect of the self-interference signal, and / or cancel the other interfering components coming from the other wireless transmission devices 40 or the user terminals. According to a particular implementation, the objective aims to minimize a mean square error between the signals transmitted by wireless transmission devices and resulting signals received by said wireless communication device 10. In this case, r zk 2 argminj (PX-W^) = argminE ^BB ' ^BB with E the mathematical expectation, and a notation representing a reduction of the dimension of the matrix M. Dimension reduction aims to obtain a matrix Mrepresentative of a system comprising the same number of transmitting and receiving antenna elements. Thus, the dimension of the matrix P (resp. X) is reduced, in order to obtain a square matrix p (resp %) whose order corresponds to the smallest number of transmitting and receiving antenna elements. Thus, in the case of an uplink scenario in which there are fewer transmitting antenna elements than receiving antenna elements, the order of the matrix p (resp. x) is equal to the number of transmitting antenna elements. By applying the well-known Lagrange multiplier method, the VFBB matrix for digital baseband post-coding is expressed as follows: WBB = (HeqH^ + v2iy^ with A^se c defined such that: ' «0 " r 1 0 ■ ■■ 0' «1 ' r 0 1 ■ ■■ 0 AmMSEJJ - ■ 0 ■ -, 0 aK . " r 0 ... ■■ 1 where ai and P are scalars depending on the coefficients of the equivalent channel matrix Heq.

[0269] Alternatively, the zeros of the matrix Aj^sg c are replaced by arbitrarily small values ​​e (e;g., g — 10'10)-

[0270] Alternatively, the matrix Aj^^eq is adapted so as to cancel the self-interference signal and / or the interference of only certain transmitting parts for which it has for example been determined that they have a significant impact in terms of interference (eg, whose received power of the interference signal is greater than a predetermined threshold).

[0271] S2000 - S500

[0272] The uplink communication method further comprises a step S2000 of simultaneously receiving signals from the user terminals 30 and the wireless transmission device 40.

[0273] During a step S3000, an analog post-coding is implemented on these signals received by applying the analog post-coding matrix, so as to obtain a plurality of streams at the output of the analog post-coder 160 of the transmission chain 100(Tx).

[0274] Then, during a conversion step S4000, each of the output streams from the analog post-coder 160 is mixed / filtered and then converted into a digital stream. This step is notably implemented by an RF chain 170 of the reception chain 100(Rx).

[0275] The communication method further comprises a step S5000 of digital post-coding of the digital streams by applying the digital post-coding matrix VFBB. This step is implemented by the digital post-coder 190 of the transmission chain 100(Tx).

[0276] [Fig. 12] illustrates the evolution of spectral efficiency as a function of a signal-to-noise ratio, for several self-interference cancellation methods, in the context of downlink communication.

[0277] The different methods compared are as follows: a full-duplex communication method without using a self-interference cancellation method ("benchmark without SIC"), the cancellation method according to the invention by applying the zero forcing criterion ("with ZF beamforming"), the cancellation method according to the invention by applying the mean square error minimization criterion ("with MMSE beamforming"), and a full-duplex communication method without interference and corresponding to an optimal theoretical result ("with perfect SIC").

[0278] [Fig. 12] illustrates that the cancellation methods by applying the zero forcing criterion and by applying the mean square error minimization criterion provide results in terms of spectral efficiency which are better than those of the full-duplex communication method without using a self-interference cancellation method.

[0279] More precisely, the curve representing the zero forcing criterion is superimposed on that representing an optimal theoretical result ("with perfect SIC"). This result illustrates the fact that the method with zero forcing criterion makes it possible to completely cancel self-interference. The cancellation method by applying the criterion of minimizing the mean square error offers lower performances than that of the method by applying the zero forcing criterion.

[0280] For an SNR equal to 25dB, with the ZF approach, the system has a spectral efficiency of approximately 8.2 bps / Hz, taking into consideration the typical conditions of a 5G network, with a bandwidth varying from 400 MHz to 28 GHz. As a result, for an SNR equal to 25dB, the wireless communication device 10 can achieve a throughput of around 3.24 Gbps for the backhaul link in xbh«mo reception, which represents the ideal case where there is no interference.

[0281] [Fig. 13] illustrates the evolution of the spectral efficiency when two user terminals are close to each other in azimuth and when two user terminals are far from each other in azimuth, by applying a zero forcing criterion and a criterion for minimizing a mean square error.

[0282] Case A 6 = 120 ° corresponds to a situation where the angular difference between the extreme user terminals is large, which therefore implies that the beams formed are more spaced apart, a fortiori "more decorrelated"; and therefore to a more favorable situation for the calculation of the inverse of the matrix product (jjH V1.

[0283] The curves illustrating the application of a zero forcing criterion for A 3 = 20° and A 6 — 120° are superimposed, which therefore illustrates that the precoder implementing a zero forcing criterion is very robust and effectively cancels out self-interference, whether the positioning of the user terminals is favorable or not.

[0284] On the other hand, a slight degradation is observable for the MMSE precoder implementing a criterion of minimizing a mean square error, but this degradation is of very low amplitude (less than 1 bps / Hz for an SNR = 25dB). This result therefore illustrates that the MMSE precoder is robust in the face of an unfavorable situation in terms of positioning of user terminals.

[0285] [Fig. 14] illustrates the evolution of spectral efficiency as a function of a number of receiving antenna elements, in the case of downlink communication, by applying the ZF criterion cancellation method.

[0286] It can be observed that by increasing the number of receiving antenna elements dedicated to the reception of backhaul signals, the spectral efficiency is improved. More precisely, for an SNR equal to 25dB, by increasing the number of receiving antenna elements by 4 additional antenna elements, the spectral efficiency is improved by less than 0.4bps / Hz. By increasing the number of antenna elements receiving 12 additional antenna elements, the spectral efficiency is increased by about 1.4bps / Hz. This is because by increasing the number of receiving antenna elements, the device receives a stronger self-interference signal, but in return also has more directionality to receive the signal of interest. The results show that increasing the number of receiving antenna elements has a positive effect since the spectral efficiency is improved.

[0287] [Fig. 15] illustrates the evolution of spectral efficiency as a function of a number of transmitting antenna elements.

[0288] It can be observed that by increasing the number of transmitting antenna elements, the spectral efficiency is improved since narrower beams are transmitted. More specifically, the improvement in terms of spectral efficiency is more significant when the number of receiving antenna elements is increased than when the number of transmitting antenna elements is increased.

[0289] This is explained by the fact that in the downlink communication with the user terminals, the signal of interest of the wireless communication device 10 corresponds to the backhaul signal of the wireless transmission device 40. Also, increasing the number of receiving antenna elements makes it possible to improve the received power of the signal of interest, and thus improves the spectral efficiency.

[0290] Furthermore, increasing the number of transmitting antenna elements allows for finer beams to be formed toward the wireless receiving device 20 and the three user terminals, but these signals are still also received by the receiving antenna element array 10(Rx) of the communication device 10. Furthermore, since the transmitting antenna element array 10(Tx) is also the source of the self-interference signal, increasing the number of transmitting antenna elements 10(Tx) also implies an increase in the power of the self-interference signal. In any case, [Fig. 15] illustrates that increasing the number of transmitting antenna elements of the wireless communication device 10 improves spectral efficiency.

[0291] Figures 16 and 17 are intended to illustrate the relevance of using a spherical wave model to model the HSI communication channel between the transmitting and receiving antenna elements of the communication device 10.

[0292] Figure 16 illustrates the evolution of the received power of a self-interference signal at a frequency f = 28GHz, as a function of tilt angle values, using a spherical wave model (SWM) and a plane wave model (PWM).

[0293] To obtain these results, no digital precoding was implemented. It can be observed that the two models have identical behavior. A minor variation is still observed for an angle value equal to 100°.

[0294] Figure 17 illustrates the evolution of the received power of a self-interference signal at a frequency / = 2GHz, as a function of tilt angle values, using a spherical wave model (SWM) and a plane wave model (PWM).

[0295] It can be observed that the spherical wave model is well adapted in case of frequency change, and that the evolution of the received power is not the same as for a frequency / = 2&GHz. On the other hand, with regard to the spherical wave model, the received power evolves in a very similar way for frequencies f = 2GHz. and f = 2&GHz.

[0296] From this observation, it can be concluded that the spherical wave model is more accurate than the plane wave model. Furthermore, these spherical wave and plane wave models have a generally similar evolution, but phase shifts between the two models are observable, in particular for angle values ​​equal to 40°, 60° and 100° corresponding to minimum values ​​of received power.

[0297] From these results, it can be deduced that whatever the frequency, the spherical wave model (SWM) is much more accurate than the plane wave model (PWM). Only an evolution of the accuracy is more visible for a frequency f = 2GHz than at 2SGHz.

[0298]

Claims

Claims

1. A full-duplex communication method implemented by a wireless communication device (10) comprising a set of receiving antenna elements and a set of transmitting antenna elements, the method comprising: • a transmission (S500), by at least one transmitting antenna element, of at least a first signal intended for at least one wireless receiving device (20, 30); and • a transmission (S500), by at least one transmitting antenna element, of a second signal (SIC) directed towards at least one of the receiving antenna elements, the second signal (SIC) aiming to reduce a power level received by the receiving antenna elements following the transmission of the first signal.

2. Communication method according to claim 1, the wireless communication device (10) comprising a plurality (NTRF) of RF chains, each RF chain being connected to at least one of said transmitting antenna elements, and one of said chains being dedicated to processing the second signal (SIC).

3. The communication method according to claim 1 or 2, wherein the wireless communication device (10) is configured to transmit NT signals simultaneously by a hybrid beamforming method, by implementing a digital precoding step (S200) and an analog precoding step (S400).

4. Communication method according to any one of claims 1 to 3, further comprising a step of determining (SI 10) an analog precoding matrix Frf by concatenation of NT depointing column vectors, one of said vectors being representative of a phase to be applied to a signal at the input of at least one of said transmitting antenna elements, so as to direct the second signal (SIC) towards said at least one receiving antenna element.

5. A communication method according to any one of claims 1 to 4, further comprising a step of determining (S 120) a baseband digital precoding FBB matrix by applying a zero-forcing criterion (ZF), the precoding FBB matrix being defined as: FbB ~ H^qHeq ) H^qAZF = ^HtqAZF, with H a matrix representative of a global communication channel, Heq a ​​matrix representative of an equivalent communication channel, H a normalization factor and AZF an objective matrix of dimension (yy + NRF^ x NT, with a number of signals emitted by the wireless communication device (10), NRF+ > 1 a number of RF chains dedicated to the processing of the second signal, said matrix AZF corresponding to the concatenation of NRF+ null row vectors of dimension 1 x NT, and a diagonal matrix of dimension NT *Nt.

6.

7.

8. The communication method of claim 5, wherein A RF+ — 1 and the objective matrix AZF is defined as '0 0 ■■■ 01 1 0 ■■■ 0 1 ■■■ 0 . .0 RRRRBR 1. Communication method according to any one of claims 1 to 4, further comprising a step of determining (S 120) a baseband digital precoding FBB matrix by applying a criterion for minimizing a mean square error (MMSE), the precoding FBB matrix being defined such that: FBB = ( H^Heq + AI ylH^AZF with He(J a matrix representative of an equivalent communication channel, A a Lagrange multiplier, AZF an objective matrix of dimension (N + Nx Nt, with t a number of signals transmitted by the wireless communication device (10), NRF+ > 1 a number of RF chains dedicated to the processing of the second signal, said matrix AZF corresponding to the concatenation of a zero row vector of dimension 1 x NT, and a diagonal matrix of dimension NT x NT, I an identity matrix of size NT x Nr, and (M 'a adjoint matrix of a matrix M. Communication method according to one of claims 1 to 9, in which the second signal (SIC) is represented by a spherical wave model.

9. A communication method according to any one of claims 1 to 8, the wireless communication device (10) being a base station, the at least one wireless receiving device (20) including a base station, and the first signal between said base stations being modeled by a plane wave model using a direct line-of-sight communication channel.

10. A communication method according to any one of claims 1 to 9, the wireless communication device (10) being a base station, the at least one wireless receiving device (20) including at least one user terminal, and the first signal between said base station and the at least one user terminal being modeled by a plane wave model using a non-line-of-sight communication channel.

11. Communication method according to one of claims 1 to 10, further comprising a step of modeling a global communication channel including: • a communication channel between the set of transmitting antenna elements and the set of receiving antenna elements of said wireless communication device (10), • and a communication channel between said wireless communication device (10) and K other devices, said global communication channel being represented by a matrix H comprising: • a first sub-matrix of dimension -1 ^10) x ^10) representative of the communication channel between the set of transmitting antenna elements and the set of receiving antenna elements of said wireless communication device (10), with y -1,yiO) the number of receiving antenna elements of said wireless communication device (10) dedicated to receiving signals from the K wireless transmitting devices equipped with a set of transmitting antenna elements and the number of transmitting antenna elements of said wireless communication device (10) dedicated to transmitting signals to the K devices, wireless reception equipped with a set of transmitting antenna elements; • a second sub-matrix of dimension ) x ^10) representative of the communication channel between said wireless communication device (10) and the K other wireless communication devices, with ) the number of antenna elements of said other devices used to communicate with said wireless communication device (10).

12. A communication method according to any one of claims 1 to 11, further comprising: • reception (S 1500) by at least one receiving antenna element of the wireless communication device (10), of third signals transmitted by other devices (20, 30), and of a fourth signal transmitted by said wireless communication device (10) to at least one wireless receiving device (20), • hybrid beamforming including a step (S4000) of digital post-coding by applying a WBB digital post-coding matrix, the method further comprising a step of determining (S 1200) a digital post-coding WBB matrix by applying the following constraints: • minimizing a mean square error between the first signals transmitted by transmitters and resulting signals received by said wireless communication device (10); and, • determination of the digital post-coding matrix WBb such that the first column of a resulting matrix W^BHeq of dimension X Nj^ is a vector of which at least one coefficient is less than or equal to a predetermined threshold, with a number of RF chains of a reception chain of the wireless communication device, a number of RF chains of a transmission chain of the wireless communication device, H^a matrix representative of an equivalent communication channel, and the adjoint matrix of a matrix M.

13. A computer program comprising instructions for implementing a communication method according to any one of claims 1 to 12, when said program is executed by a computer.

14. A computer-readable recording medium having a computer program recorded thereon according to claim 13.

15. Wireless communication device (10) configured to communicate in full-duplex, and comprising: • a set of receiving antenna elements; • a set of transmitting antenna elements; • a transmitting module configured to control a transmission of at least one first signal intended for at least one wireless receiving device (20, 30), the transmitting module also being configured to control a transmission of a second signal (SIC) directed towards at least one of the receiving antenna elements, the second signal (SIC) aiming to reduce a power level received by the receiving antenna elements following the transmission of the first signal.

16. Device according to claim 15, the wireless communication device (10) comprising a plurality (NTRF) RF chains, each RF chain being connected to a subset of at least one transmitting antenna element, and one of said chains being dedicated to processing the second signal.

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