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 to wireless communications implemented on radio networks such as mobile networks (e.g., 3G, 4G, 5G, B5G, etc.), Wi-Fi, etc. It relates more specifically 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 by no means limiting, application in the case of a MIMO (Multiple Input Multiple Output) type wireless communication device using several antennas in transmission and reception, and in particular in the case of a massive MIMO type wireless communication device relying on a large number of antennas (typically from 16 to 128 antennas, this number being expected to increase in the future). Previous technique

[0003] In order to adapt to the continuous and ever-faster growth of data traffic emitted by wireless communication systems, various technologies are now being implemented, and are still being improved with a view to optimal use in the years to come.

[0004] Among these technologies, and more specifically in the context of MIMO-type wireless communication systems, it is known to configure a wireless communication device, such as a base station or a mobile phone, to simultaneously transmit and receive several data streams via an antenna array (i.e., a set of antenna elements or elementary antennas) equipping said wireless communication device. This is referred to as "full-duplex" communication when data is transmitted and received simultaneously, and more specifically as "in-band full-duplex" communication when data is 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-language 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 transmitting antenna elements with receiving antenna elements. Indeed, since signal reception and transmission are implemented simultaneously (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, even though that first base station only wants to receive signals from other devices. This unwanted signal is generally called a "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 free space attenuation is significant, and where the signal of interest (e.g., 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 and 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 channel in order to suppress the self-interference signal.

[0009] However, these methods cancel the self-interference signal by passing into the analog and / or time domains. 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 deviation between the two signals can induce significant errors. Description of the invention

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

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

[0012] These transmissions are implemented simultaneously. The advantages of full-duplex in-band communication lie particularly in the fact that the wireless communication device according to the invention is capable of simultaneously transmitting and receiving signals in an associated frequency band. Such arrangements advantageously avoid the need to use multiple frequency bands, which are scarce resources, for both transmitting and receiving signals, thus improving the spectral efficiency of said device.

[0013] Generally speaking, a person skilled in the art may refer to the following document for further details concerning 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 the classical methods of canceling self-interference - which, after conversion, subtract a self-interference signal from a received signal - includes the transmission of a signal (e.g., the second signal) including data enabling the reduction (or cancellation) of a power level received by the receiving antenna elements of the wireless communication device, following the emission of a first signal by the same wireless communication device.

[0015] At least a first and second signal are emitted 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 said to be "downward link".

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

[0018] In particular modes of implementation, the communication method may further include one or more of the following characteristics, taken individually or in all technically possible combinations.

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

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

[0021] In particular embodiments, the communication method further comprises: • a baseband digital precoding step to obtain NTRF streams; • 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 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 includes a step of determining an analog precoding Frf matrix, the second signal being emitted according to said analog precoding Frf matrix.

[0023] In particular embodiments, the communication method further includes a step of determining an analog precoding Frf matrix by concatenation of NT column vectors for pointing, one of said vectors being representative of a phase to be applied to an input signal 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 includes a step of determining a baseband digital precoding FBB matrix.

[0025] In particular embodiments, the communication process It also includes a step of determining a precoding F BB matrix baseband digital 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 representative matrix of a global communication channel, Heq a ​​representative matrix 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 processing 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 embodiments, 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 includes a step of determining a digital baseband precoding FBB matrix by applying a mean squared error minimization criterion, the precoding FBB matrix being defined such that:

[0031] Fbb= (H?qHeq + Àl)'lH^AZF

[0032] with Heq a ​​representative matrix of 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 channels dedicated to processing the second signal, said matrix AZF 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 antenna elements and the 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 follows:

[0036] *-Friend

[0037] with pej'l' a complex gain representing 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 with a reference frame linked to the set of receiving antenna elements, and X a vector going from the center Or, to the same element of the set of receiving antenna elements.

[0040] In particular embodiments, the wireless communication device is a base station, 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 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 communication channel without direct line of sight.

[0042] In particular embodiments, the communication method further comprises a step of modeling an overall 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 (e.g., 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 submatrix of dimension yK-1 o) representing 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 devices dedicated to receiving signals from K wireless transmitting devices equipped with a set of transmitting antenna elements and the number transmitting antenna elements of said wireless communication device 10 dedicated to transmitting signals to K wireless receiving devices equipped with a set of transmitting antenna elements; a second sub-matrix of dimension ) x representing 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' user terminal receiving antenna elements 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 antenna elements of 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 (UEs), and said second sub-matrix comprises: a third submatrix of x-representative dimension channels between all the transmitting antenna elements of said wireless communication device and the 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 transmission systems equipped with a set of transmitting antenna elements, and • a fourth x-dimensional submatrix 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: • the transmission, by at least one transmitting antenna element, of at least one first signal intended for at least one wireless receiving device; and • an emission, by at least one other transmitting antenna element, of the second signal in the form of a beam directed towards at least one of the receiving antenna elements, the second signal aiming to reduce (or even cancel) a power level received by the receiving antenna elements following the emission of the first signal, one of said RF chains being dedicated to the processing of 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 emitted by other devices, and of a fourth signal emitted by said wireless communication device intended for at least one wireless receiving device, • a hybrid beam formation including a digital post-coding step by applying a Wgg digital post-coding matrix, the process further comprising a step of determining a WBB digital post-coding matrix by applying the following constraints: • minimization of the root mean square error between the first signals emitted 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 that the first column of a resulting WBBHeq matrix of dimension X Nj-F is a vector of which at least one coefficient is less than or equal to a predetermined threshold, with ]^FF a number of RF channels in a receiving channel of the wireless communication device, ]yFF a number of channels 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 can be any entity or device capable of storing the program. For example, the medium can include 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 can be a transmissible medium such as an electrical or optical signal, which can be transmitted via an electrical or optical cable, by radio, or by other means. The program according to the invention can, in particular, be downloaded onto an Internet-type network.

[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 process 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 transmitting module configured to control the transmission of at least one first signal intended for at least one wireless receiving device, the transmitting module also being configured to control the transmission of a second signal directed towards at least one of the receiving antenna elements, the second signal intended to reduce a level of power received by the receiving 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 could be a base station, etc.

[0053] In particular embodiments, the wireless communication device comprises a plurality of RF channels, each RF channel is connected to a subset of at least one transmitting antenna element, and one of said channels is dedicated to the processing of 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 emitted by other devices, and of a second signal emitted by said wireless communication device intended for at least one wireless receiving device, • a hybrid beamforming process including a digital post-coding step by applying a WBB digital post-coding matrix, the process further comprising a step of determining a WBB digital post-coding matrix by applying the following constraints: • minimizing the root mean square error between the first signals emitted by the other devices and the resulting signals received by said wireless communication device; and, • determination of the digital post-coding WBB matrix such that the first column of a resulting WBBHeq matrix of dimension x is a vector of which at least one coefficient is less than a predetermined threshold, with a number of RF channels of a receiving channel of the wireless communication device, a number of RF channels of a transmitting channel of the wireless communication device, Heq a ​​representative matrix 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 as follows:

[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 a diagonal matrix of dimension NR x and I an identity matrix of size 2V R x 2V Rt

[0058] In particular modes of implementation 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 features and advantages of the present invention will become apparent from the description below, with reference to the accompanying drawings, which illustrate an example of an embodiment without being limiting in any way. In the figures:

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

[0063] [Fig.2] [Fig.2] is a detailed view of [Fig.1] including the communication channels nization considered in connection with a wireless communication device (10);

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

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

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

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

[0068] [Fig.7] [Fig.7] illustrates, in the form of a flowchart, the main steps of a downlink communication method, according to an example of 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 communications considered in connection with a wireless communication device (10) are considered;

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

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

[0073] [Fig. 12] [Fig. 12] illustrates the evolution of 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 spectral efficiency when two user terminals are close to each other in azimuth and when two user terminals are far apart in azimuth, by applying a zero-force criterion and a mean squared error minimization criterion;

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

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

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

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

[0079] Downlink communication

[0080] Fig. 1 is an example of a communication system in which a full-duplex, downlink communication method is implemented.

[0081] The wireless communication system is a multi-antenna or MIMO system. This system comprises a wireless transmitting device 40, a wireless communication device 10 according to the invention, a wireless receiving device 20, and a plurality of user terminals 30. A user terminal 30 corresponds, for example, to a laptop computer, a personal assistant, a connected object, or a smartphone.

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

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

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

[0085] Each wireless transmitting device 40 and wireless receiving device 20 is itself equipped with at least one antenna (e.g., at least one antenna element). There is no limitation on the number of antennas equipping each of said devices 40 and 20.

[0086] In this embodiment, and for the sake of simplicity in the description, it is assumed that each user terminal 30 is equipped with only one antenna, and that they do not communicate in full-duplex. It should be noted, however, that there is no limitation on the number of antenna elements on the user terminals.

[0087] Thus, the communication device 10 is capable of receiving a signal from the wireless transmitting device 40, transmitting a signal to the wireless receiving device 20, and transmitting another signal to at least one user terminal 30, all simultaneously ("full-duplex"). Devices 20 and 40 are also configured to communicate in full-duplex.

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

[0089] In the present embodiment, and for the sake of simplicity in the description, it is also assumed that communication between devices 40, 10, and 20 is implemented in only one direction. However, since the problem is symmetrical, the following developments can be easily generalized by a person skilled in the art to cases where bidirectional communication is implemented between devices 40, 10, and 20.

[0090] Devices 10, 20, 30, and 40 belong to a wireless communications network (not shown in [Fig. 1]) and are capable of communicating with each other in a frequency band associated with this wireless communications network. For the remainder of this description, said telecommunications network is considered, without limitation, to be a 5G mobile network.

[0091] It should be noted, however, that the invention remains applicable to other types of telecommunications networks, such as, for example, a GSM mobile network, 3G (the third generation of mobile network standards), 4G (the fourth generation of mobile network standards), 5G (the fifth generation of mobile phone network standards) and / or B5G (acronym for "Beyond 5G"). The invention also remains applicable to a Wi-Fi (acronym for "Wireless Fidelity") network, a WiMAX (acronym for "Worldwide Interoperability for Microwave Access") network, a satellite internet access network, etc. Generally speaking, there are no limitations on 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 transmitted over this network.

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

[0093] A base station is sometimes called "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, devices 10, 20 and 40 conform to 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 be noted, however, that the invention is applicable regardless 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 devices 10, 20 and / or 40 are access points (AP) of a local network ("Local Area Network" according to Anglo-Saxon terminology), such as a wireless local network, e.g., conforming to IEEE 802.11 standards.

[0097] Fig. 2 is a detailed view of Fig. 1 including the communication channels considered in relation to the wireless communication device 10.

[0098] As mentioned previously with reference to [Fig.1], the communication device 10 is configured to be able to simultaneously receive a signal from the wireless transmitting device 40, transmit a signal to the wireless receiving device 20, and transmit other signals to three user terminals 30.

[0099] For these reasons, the wireless transmitting device 40 is represented as its transmitting antenna element array, referenced 40(Tx), the wireless receiving device 20 is represented as its receiving antenna element array, referenced 20(Rx), and the communication device 10 is represented as its transmitting antenna element array 10(Tx) and its receiving antenna element array 10(Rx). In order to make the model as generic as possible, in this example, a tilt angle is assumed between the arrays 10(Tx) and 10(Rx), such 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 transmitting antenna element array 10(Tx) of the communication device 10 to the receiving antenna element array 10(Rx) of the same communication device 10; • a "backhaul" communication channel Hbha^io going from the transmitting antenna element array 40(Tx) of the wireless transmitting device 40 to the receiving antenna element array 10(Rx) of the communication device 10; • a "backhaul" communication channel from the network transmitting antenna elements 10(Tx) to the receiving antenna element array 20(Rx) of the wireless receiving device 20; • a Hue communication channel, going 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 assembly 10(Rx) and the nth transmitting antenna element of assembly 10(Tx) is then modeled as follows:

[0103] — æj]'J2_ e- Aswm.^

[0104] with pe# a complex gain representative of a communication channel between a center Op of the transmitting antenna element set and a center Or of the receiving antenna element set, AL an amplitude fluctuation with D a distance between the center Orx and the center Dp, Dm>n a distance between the same antenna element of the receiving antenna element set 10(Rx) and the nth* antenna element of the transmitting antenna element set 10(Tx), A 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 to 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" communication channels -^B#4O-*1() and HBH^^20 are modeled as line-of-sight communication channels, and the signals passing through these channels are modeled by a plane wave model.

[0109] This modeling proves particularly suitable when the wireless communication device 10, the wireless transmitting device 40 and the wireless receiving device are base stations on top of which the antenna sets 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-casting method, so that only the pointing vectors corresponding to the transmitting antenna element set and the pointing vectors corresponding to the receiving antenna element set are required. The Hbh4(^iq and Hbh matrices of the backhaul channels are then defined as follows: 101111 C)e(C cf H BH ^=«HîhC Cf . ... . . .2 aveC / ^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 assembly 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 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 elevation angle fi# V7## the Departure Directions (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 in and above consider the special case where the antenna element sets are uniform planar antenna arrays ("Uniform Planar Array" according to Anglo-Saxon terminology), and where the antenna elements are regularly spaced half a wavelength apart.

[0114] Furthermore, since the backhaul channels are modeled as line-of-sight communication channels, the DoDs of the transmitting element set of the communication device 10 (respectively 40) are identical to the arrival angles ("Direction of Arrival" according to Anglo-Saxon terminology) of the receiving antenna element set 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, signals transmitted between a user terminal and a communication device such as a base station are frequently reflected by reflectors before reaching their target. Therefore, the HUE DL communication channel is modeled as a communication channel without a direct line of sight. Furthermore, since user terminals are typically located at a certain distance (e.g., from a few tens of meters to about thirty kilometers) from the base station to which they are connected, the signals passing through these channels are modeled by a plane wave model.

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

[0118] To model the environment of the user terminals 30, it 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 [O, 2æ] for the azimuth.

[0119] As mentioned previously with reference to Figure 1, for the sake of simplification From the description, it is assumed that each user terminal 30 is equipped with only one antenna (e.g., isotopic). Therefore, the number of receiving antenna elements to consider corresponds to the number (K') of user terminals 30 connected to the wireless communication device 10, and the channel matrix is ​​then constructed by concatenating column vectors, each column vector representing one of the K user terminals. The uth 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 1st path, 1i the delay associated with the 1st 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 1st user terminal, 6 / and ¢l the azimuth and elevation angles of the DoD of the 1st path. The dimension of the channel matrix is ​​then x with M^up 'c number 10 transmission antenna elements of the communication device dedicated to data transmission to user terminals 30.

[0122] Global Channel Matrix

[0123] The overall channel matrix H is then formed by a vertical concatenation of three sub-matrices: • a first sub-matrix [ 57C SI S / ] of dimension x representing 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 receiving "backhaul" signals (e.g., signals emitted by the wireless transmitting device 40) and the number of transmitting antenna elements of the wireless communication device 10; • a second submatrix [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 reception of the wireless receiving device 20; • a third submatrix ^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 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 transmit antenna element set 10(Tx) of the wireless communication device 10 to the receive antenna element set 10(Rx) of the 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 signal in downlink to K user terminals.

[0125] The overall 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 made possible by the use of a dedicated RF chain (and transmitting 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 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 from the Xth RF chain of the wireless communication device 10.

[0131] It is important to note here that this device Y would ideally only want to receive the signal from the Yth RF channel of the wireless communication device 10, but not that of the Xth RF chain of the wireless communication device 10 which therefore corresponds to an interference signal.

[0132] Fig. 3 represents an example of the 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 being intended to reduce a power level received by the receiving antenna elements 10(Rx) following the transmission of another signal, by this communication device 10 and to another device.

[0134] As illustrated in Figure 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 phase quadrature modulation. This constellation modulation block 110 is connected to a digital precoder 120. The digital precoder 120 is itself connected at its output to NTRF modulation blocks 130 implementing, for example, OFDM (Orthogonal Frequency-Division Multiplexing). Each modulation block 130 is connected at output to an RF (acronym for "Radio Frequency") chain 140, of known design per se, and the NTRF RF chains are connected to an analog precoder 150 to which the transmitting 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 energy consumption offered by the use of an analog beamforming method.

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

[0137] The receiving chain 100(Rx) includes a plurality of receiving antenna elements connected to an analog post-coder 160. This post-coder is connected at its 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. quadrature or a quadrature phase modulation.

[0138] In the scenario described in Figures 1 and 2, the only signals expected by the receiving chain 100(Rx) of the communication device 10 are those from the wireless transmitting device 20. Therefore, only one RF chain 170 and the modulation block 180 to which it is connected are activated. Furthermore, since only one RF chain 170 is required, it can be directly connected to the block 200, without the need for a digital post-encoder 190.

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

[0140] As represented in [Fig. 3], the RF chain architecture is partially connected. The following developments are, however, easily adaptable by those skilled in the art to the case where the RF chain architecture is fully connected.

[0141] Figure 4 shows an example of the distribution of antenna element sets receiving and transmitting a wireless communication device 10 comprising five RF transmission channels, of the communication system of the [Fig.1].

[0142] As illustrated in Figure 4, the communication device comprises an assembly 10(Tx) of transmitting antenna elements of dimension 10x4. This assembly 10(Tx) is subdivided into five sub-assemblies of dimension 2x4; • a first RX, SIC subset dedicated to the emission of a self-interference signal (SIC) in the form of a beam directed towards a subset of receiving antenna elements of said communication device 10; • a second TX subset, BH10 20, dedicated to transmitting a signal in the form of a beam directed towards the wireless receiving device 20; • a third TX subset, 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 subset, UE30-2, dedicated to transmitting a signal in the form of a beam directed towards a user terminal 30-2; and • a fifth TX subset, 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 subassemblies is indirectly connected to an RF 140 chain of the transmission chain 100(Tx) of the communication device 10. In other words, this distribution of the assembly 10(Tx) of transmitting antenna elements into five subassemblies is made possible by the use of at least five RF 140 chains. And one of these five RF 140 chains is dedicated to the transmission of a signal (SIC) intended to reduce, or even cancel, a received power level resulting from a self-interference (SI) signal due to another signal simultaneously transmitted by the communication device 10.

[0144] The communication device 10 further comprises an assembly 10(Rx) of receiving antenna elements of dimension 8x4. This assembly 10(Rx) is subdivided into four sub-assemblies of dimension 2x4; • a first RX subset, BH4Q 10 dedicated to receiving a signal from the wireless transmitting device 40; • a second RX subset, UE30-1, dedicated to receiving a signal from a user terminal 30-1; and • a third RX subset, UE30-2 dedicated to receiving a signal from a user terminal 30-2. • a fourth RX subset, 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 signal expected in reception is that of the BH40—>10 link.

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

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

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

[0149] As illustrated in [Fig. 6], the wireless communication device 10 has the hardware architecture of a computer. Thus, the wireless communication device 10 includes, in particular, a processor 1, random access memory 2, read-only memory 3 and non-volatile memory 4. It also includes 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 stored a computer program PROG_DL according to the invention, comprising instructions for executing steps of the communication method (downlink) as proposed below. The PROG_DL program defines one or more functional modules of the device, which rely on or control the hardware elements 1 to 5 mentioned above, and which include in particular a MOD_TX transmission module 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) intended to reduce a level of power received by the receiving antenna elements following the emission of the first signal.

[0151] Furthermore, the wireless communication device 10 may also include other modules, in particular to implement particular modes of the full-duplex communication process, as described in more detail later.

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

[0153] As illustrated by [Fig.7], the downlink communication method includes a first step S100 of configuration of this wireless communication device 10, which includes substeps SI 10 and S120.

[0154] S110

[0155] The SI substep 10 is a step for 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] Thanks to the use of an RF chain dedicated to the processing of 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 representative vector of 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 overall channel matrix as defined in the section "Overall 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 noise received by each receiving antenna element of the set of antenna elements 10(Rx), v_[n the vector self ~ ' •••-'] representative of the signals emitted by the wireless transmitting device 40 and representing the signals of interest for 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 have a modulus equal to 1.

[0160] According to a particular implementation, the matrix F RF results from the concatenation of NT depointing column vectors ek, each vector being representative of a phase at apply 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 RF chain architecture is partially connected, these off-pointing vectors ek are defined as follows:

[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 the direction £ 'c name^rc of antenna element lines from set 10(ZA.) dedicated to the direction k, and jj / 'u 'c number of antenna element columns from set 10(ZA) dedicated to the direction k, with Zx c{7\; ÆJ.

[0164] The Frf matrix is ​​then constructed by vertical concatenation of the pointing vectors ek which point towards the set of receiving antenna elements of the wireless communication device 10 (so as to transmit the self-interference signal SIC), towards the wireless receiving 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 Ie pointing vector of dimension x 1 pointing towards the set of receiving antenna elements of the wireless receiving device 20, eUEi is the pointing vector of dimension jyjO°) x । pointing towards the different directions of the K user terminals. The resulting matrix Frf is then of dimension / 10) + 1°), fxf + 2 ), with a number of elements transmitting antenna elements of the communication device 10 dedicated to transmitting signals to the wireless receiving device 40 and to the user terminals 30, and M^xSic 'C name^re transmitting antenna elements of the communication device 10 dedicated to the transmission of the self-interference signal.

[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 power received from this self-interference signal.

[0169] More generally, when the communication system includes 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 matrix Frf 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 matrix IIRFcq is then written:

[0173] RF.eq -

[0174]

[0175] with IK r an identity matrix of dimension K x K • This IVRF£q matrix is ​​of dimension 4- x (K +K + 1)' and Puis9ue '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 identical to the number of receivers, and that a hybrid beamforming method can be implemented.

[0176] The IK matrix illustrates the fact that the 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 capacity to perform beamforming. In this case, the shape of the Wppeq matrix is ​​similar to that previously mentioned, but the IF identity matrix is ​​replaced by the pointing vectors of each user terminal 30.

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

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

[0180] S120

[0181] The downlink communication method further includes an S120 step for determining a baseband digital precoding FBB matrix.

[0182] Digital precoding FBB allows manipulation of the equivalent channel matrix Heq to produce a desired effect. Unlike analog precoding, there are no hardware constraints that impose mathematical constraints on the expression of Fbb, and the expression of FBB is therefore determined according to a specific objective.

[0183] S120. application of a zero forcing criterion

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

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

[0186] with H the representative matrix of the overall communication channel, Heq the representative matrix of an equivalent communication channel, 1 a normalization factor such that —----!---- , an objective matrix of dimension NT + 1 x NT, with Nt is 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 matrix MZF of dimension NT x NT. In a particular implementation, this diagonal matrix MZF 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 emitted by the transmitting antenna elements 10(Tx) and received by the receiving antenna elements 10(Rx) of the same wireless communication device 10. The role of the diagonal matrix of dimension NT x NT is to ensure that each receiver of the communication system receives a signal free from interference caused by another receiver of the communication system.

[0190]

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

[0192] Matrix Y illustrates that applying the zero-forcing criterion cancels the effect of the self-interference signal due to the signal emitted 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 transmitting device 40, as well as noise. Applying such a ZF pre-encoder also ensures that the receiving antenna elements 20(Rx) of the wireless receiving device 20 and the K antennas of the user terminals receive only their signal of interest, without interference from other surrounding wireless receiving devices or user terminals.

[0193] Alternatively, the zeros of the AZF matrix are replaced by arbitrarily small values ​​£ (e ;g., g — 10'10), in order to adapt the calculation of the matrix inversion in the equation of Fbbzf 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 interferences of only certain emitting parts for which it has been determined, for example, that they have a significant impact in terms of interference (e.g., whose received power of the interference signal is greater than a predetermined threshold).

[0195] S120. Application of a mean square error minimization criterion

[0196] According to a second example of implementation, the precoding matrix F BB The digital baseband is determined by applying a mean squared error minimization (MSE) criterion. The application of this criterion is illustrated through the communication system shown in [Fig. 1], but the following developments can nevertheless be easily generalized by a person skilled in the art to cases 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 the representative vector of [■'■BffttFlO XUE& * • • ' xUEK-\ j signals of interest received by the different receivers (e.g., 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 squared error between the X and Y signals and is formalized by the following Oi equations:

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

[0200] with P' the diagonal matrix comprising 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 squared error, and || || the Frobenius norm. He F

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

[0203] with Heq the representative matrix of 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 baseband digital precoding step S200 by applying the digital precoding matrix FBB (e.g., Fbbzf or Fbb) so as to obtain a plurality of output stream from 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 an analog mixing and / or filtering step is implemented on said analog stream, 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 includes an analog precoding step S400 of the RF data streams by application of the analog precoding matrix Fff, so as to obtain signals in the form of beams directed towards the wireless receiving device 20 and the user terminals 30, but also a self-interference signal intended to reduce a level of power received by the receiving antenna elements following interference from the transmission of signals intended for the wireless receiving 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 includes a step S500 of simultaneous emission of the following signals in the form of beams: • a signal directed towards the wireless receiving device 20; • signals directed towards 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 intended to reduce a level of power received by the receiving antenna elements following the emission of other signals.

[0210] Uplink communication

[0211] The invention has hitherto been described in the case of downlink communication between the wireless communication device 10 and the user terminals 30. Figures 8 to 11 illustrate this time the case of uplink communication, where the effect of self-interference is reduced or even canceled by processing at the level of the receiving 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, referred to in [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 Hue, ul (which replaces the HUE DL channel) and which is this time directed from user terminals 30 to the transmit antenna element network 10(Tx) of the wireless communication device 10.

[0215] HUE ul communication channel

[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 reason, the HUE UL communication channel is modeled as a communication channel without direct line of sight. Furthermore, since user terminals are typically at some 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, representing the channel between the user terminals and the wireless communication device 10, is implemented using a ray-tracing method. More specifically, for each user terminal, a direct beam emitted by the given user terminal 30 towards the communication device 10 is defined, and then L - 1 other beams are constructed whose Origin Direction (DoD) is separated by an angle of A2 and _ in both elevation and in azimuth relative to the main beam.

[0218] To model the user terminal environment, it then follows that L Beams are emitted from each 30 user terminal, and the angle of arrival DoA of these L beams at the level of 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 sake of simplifying the description, it is assumed that each user terminal 30 is equipped with only one antenna (e.g., isotopic). Therefore, 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 concatenating 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 first path, ri the delay associated with the first 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 first terminal user, and ( / )^ the azimuth and elevation angles of the user terminal 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 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 uplink self-interference. Also, the matrix of global channel H of dimension + x + K") is then defined as follows:

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

[0224] Fig. 10 represents an example of the implementation of a wireless communication device (10) implementing an uplink communication method.

[0225] As illustrated in [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 phase quadrature modulation. This constellation modulation block 110 is connected (directly or indirectly) to a modulation block 130 implementing, for example, OFDM (Orthogonal Frequency-Division Multiplexing).

[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 output to an RF chain 140, itself connected to an analog precoder 150 to which the transmitting 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 low hardware complexity and low power consumption energy provided by using an analog beamforming method.

[0229] The receiving chain 100(Rx) includes a plurality of receiving antenna elements 10(Rx) connected to an analog post-coder 160. This post-coder is connected at its 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 phase quadrature modulation.

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

[0231] As represented in [Fig.10], the RF chain architecture is partially connected. The following developments are, however, easily adaptable by those skilled in the art to the case where the RF chain architecture is fully connected.

[0232] Figure 11 illustrates, in flowchart form, the main steps of an uplink communication method, according to an example of an 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 described above with reference to Figures 1 to 7. Alternatively, this uplink communication method is implemented in combination with the downlink communication method described above. 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 includes a first step S1000 of setting up this wireless communication device 10, which includes substeps S1100 and S1200.

[0235] S1100

[0236] The SI substep 100 is a step for determining an analog post-coding matrix FF^ which will be used to configure the analog post-coding module 160, and an equivalent analog pre-coding 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 from the

[0244] ek = a in the following way:

[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 of diagonal power representing the power allocated to the signals emitted by each of the transmitters of the communication system, etz 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 overall matrix H, and that the interference signal xbhi0^20 is included in the vector x. This is 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 column vectors of pointing each vector being representative of a phase to be applied to an input signal of at least one of said receiving antenna elements.

[0243] According to a particular implementation, when the RF chain architecture is partially connected, these off-pointing vectors ek are defined as follows: 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 transmitting or receiving antenna of the wireless communication device 10, k a direction index having a value among {UEk_0, UE^ K" ct 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 pointing 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 can then be written as follows:

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

[0249] with eBH4O-»io the X-dimensional pointing vector pointing towards the direction of the entire antenna element assembly during transmission of the transmitting device wireless 40' euEfc the pointing vector of dimension . x [ pointing towards 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 communication device 10.

[0250] The equivalent analog precoding FRp_eci matrix 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 as:

[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 Frf^ matrix 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 baseband digital post-coding. The problem to be solved is expressed by the following Oi 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 one "1" at position / and "0" elsewhere. By construction, the direction of constraint (¾) is explained as follows: the coefficient located in the row and the fth column of the resulting matrix W^Heq must be equal to "0", so that the effect of the equivalent channel of the i-th transmitter on the k-th receiver is completely cancelled. Alternatively, this coefficient should not be equal to "0", but equal to a predetermined value. It 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 from other wireless transmitting devices 40 or user terminals. According to a particular implementation, the objective is to minimize the root mean square error between the signals emitted by wireless transmitting devices and the resulting signals received by said wireless communication device 10. In this case, r zk 2 argminj (PX-W^) = argminE ^BB ' ^BB with E the expected value, and a notation representing a reduction of the dimension of matrix M. Dimensionality reduction aims to obtain a representative matrix M of a system with the same number of transmit and receive antenna elements. Thus, the dimension of the matrix P (resp. X) is reduced to obtain a square matrix p (resp. %) whose order corresponds to the smallest number of transmit and receive antenna elements. Therefore, in an uplink scenario with fewer transmit antenna elements than receive antenna elements, the order of the matrix p (resp. x) is equal to the number of transmit 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 interferences of only certain emitting parts for which it has been determined, for example, that they have a significant impact in terms of interference (e.g., whose received power of the interference signal is greater than a predetermined threshold).

[0271] S2000 - S500

[0272] The uplink communication method further includes an S2000 step of simultaneous reception of signals from the user terminals 30 and the wireless transmitting device 40.

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

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

[0276] Figure 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 the use of a self-interference cancellation method ("benchmark without SIC"), the cancellation method according to the invention by application of the zero-forcing criterion ("with ZF beamforming"), the cancellation method according to the invention by application of the mean squared error minimization criterion ("with MMSE beamforming"), and a full-duplex communication method without interference and corresponding to a theoretical optimal result ("with perfect SIC").

[0278] Fig. 12 illustrates that cancellation methods by applying the zero-forcing criterion and by applying the mean squared error minimization criterion offer spectral efficiency results that 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 a theoretical optimal result ("with perfect SIC"). This result illustrates that the method with the zero-forcing criterion completely eliminates self-interference. The cancellation method using the mean squared error minimization criterion, on the other hand, offers lower performance than the method using the zero-forcing criterion.

[0280] For an SNR of 25dB, using the ZF approach, the system has a spectral efficiency of approximately 8.2 bps / Hz, taking into account typical 5G network conditions with a bandwidth ranging from 400 MHz to 28 GHz. It follows that for an SNR of 25dB, the wireless communication device 10 can achieve a throughput of around 3.24 Gbps for the backhaul link in receive mode, which represents the ideal case where there is no interference.

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

[0282] The case A 6 = 120° corresponds to a situation where the angular gap between the extreme user terminals is large, which therefore implies that the beams formed are more spaced out, a fortiori "more uncorrelated"; 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 self-interference, regardless of whether the positioning of the user terminals is favorable or not.

[0284] In contrast, a slight degradation is observed for the MMSE precoder implementing a mean squared error minimization criterion, but this degradation is of very small magnitude (less than 1 bps / Hz for an SNR of 25 dB). This result therefore illustrates that the MMSE precoder is robust in the face of an unfavorable situation in terms of user terminal positioning.

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

[0286] It can be observed that by increasing the number of receiving antenna elements dedicated to receiving backhaul signals, spectral efficiency is improved. More precisely, for an SNR of 25 dB, increasing the number of receiving antenna elements by 4 additional antenna elements improves spectral efficiency by less than 0.4 bps / Hz. By increasing the number of antenna elements With the addition of 12 more antenna elements, spectral efficiency is increased by approximately 1.4 bps / Hz. This is because increasing the number of receiving antenna elements results in a stronger self-interference signal, but in return, it also provides greater directivity for receiving the signal of interest. The results show that increasing the number of receiving antenna elements has a positive effect, as spectral efficiency is improved.

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

[0288] It can be observed that by increasing the number of transmitting antenna elements, spectral efficiency is improved since narrower beams are emitted. More precisely, the improvement in 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 downlink communication with user terminals, the signal of interest of the wireless communication device 10 corresponds to the backhaul signal of the wireless transmitting device 40. Also, increasing the number of receiving antenna elements improves the received power of the signal of interest, and thus improves spectral efficiency.

[0290] Furthermore, increasing the number of transmit antenna elements allows for the formation of finer beams towards 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. Moreover, since the transmit antenna element array 10(Tx) is also the source of the self-interference signal, increasing the number of transmit antenna elements 10(Tx) also implies an increase in the power of the self-interference signal. Nevertheless, [Fig. 15] illustrates that increasing the number of transmit 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 power received from 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 nevertheless observed for an angle value of 100°.

[0294] Figure 17 illustrates the evolution of the power received from 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 the case of frequency change, and that the evolution of the received power is not the same as for a frequency ω = 2 GHz. On the other hand, with regard to the spherical wave model, the received power evolves in a very similar way for frequencies ω = 2 GHz and ω = 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, particularly for angle values ​​of 40°, 60° and 100°, corresponding to minimum values ​​of received power.

[0297] From these results, it can be deduced that, regardless of the frequency, the spherical wave model (SWM) is much more accurate than the plane wave model (PWM). Only the change in accuracy is more noticeable at a frequency f = 2 GHz than at 25 GHz.

[0298]

Claims

Demands

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: • an emission (S500), by at least one transmitting antenna element, of at least one first signal intended for at least one wireless receiving device (20, 30); and • an emission (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) intended to reduce a level of power received by the receiving antenna elements following the emission of the first signal.

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

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

5. A communication method according to any one of claims 1 to 4, further comprising a step (S 120) of determining a digital baseband precoding FBB matrix by applying a zero-forcing criterion (ZF), the precoding FBB matrix being defined as follows: FbB ~ H^qHeq ) H^qAZF = ^HtqAZF, with H a representative matrix of a global communication channel, Heq a ​​representative matrix 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 processing the second signal, said matrix AZF corresponding to the concatenation of NRF+ nuis row vectors of dimension 1 x NT, and a diagonal matrix of dimension NT *Nt.

6.

7.

8. A communication method according to claim 5, in which A RF+ — 1 and the objective matrix AZF is defined such that '0 0 ■■■ 01 1 0 ■■■ 0 1 ■■■ 0 . .0 RRRRBR 1. A communication method according to any one of claims 1 to 4, further comprising a step of determining (S 120) a digital baseband precoding FBB matrix by applying a mean squared error minimization (MSE) criterion, the precoding FBB matrix being defined such that: FBB = ( H^Heq + AI ylH^AZF with He(J a matrix representing an equivalent communication channel, A a Lagrange multiplier, AZF an objective matrix of dimension (N + Nx Nt, with t a number of signals emitted by the wireless communication device (10), NRF+ > 1 a number of RF chains dedicated to processing 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. A communication method according to any one of claims 1 to 9, wherein 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 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 communication channel without direct line of sight.

11. A communication method according to any one of claims 1 to 10, further comprising a step of modeling an overall 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 overall communication channel being represented by a matrix H comprising: • a first submatrix of dimension -1^10) x^10) representing 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 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 K devices, wireless receivers equipped with a set of transmitting antenna elements; • a second sub-matrix of dimension ) x ^10) representing 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 emitted by other devices (20, 30), and of a fourth signal emitted by said wireless communication device (10) to at least one wireless receiving device (20), • a hybrid beamforming process including a digital post-coding step (S4000) by applying a digital post-coding WBB matrix, the process further comprising a step of determining (S 1200) a WBB matrix for digital post-coding by applying the following constraints: • minimization of the root mean square error between the first signals emitted by transmitters and the resulting signals received by said wireless communication device (10); and, • determination of the WBb matrix of digital post-coding 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 channels of a receiving channel of the wireless communication device, a number of RF channels in a transmission chain of the wireless communication device, H^a representative matrix of an equivalent communication channel, and the adjoint matrix of a matrix M.

13. 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. Computer-readable recording medium on which a computer program according to claim 13 is recorded.

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 the 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 the transmission of a second signal (SIC) directed towards at least one of the receiving antenna elements, the second signal (SIC) intended to reduce a level of power 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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