Wireless communication system and method

Abstract

The present disclosure provides a wireless communication system comprising: at least one DCS having a surface, the surface comprising a scattering element having a controllable phase shift; at least one transmitter for transmitting the encoded radio frequency signal to the at least one receiver during a plurality of time slots; and a controller. The controller controls the at least one transmitter to generate the encoded radio frequency signal during the plurality of time slots based on a space time DCS code (space time DCS code, STDC). The controller also controls a set of scattering elements of the at least one DCS during the plurality of time slots based on the STDC. The STDC depends on a total number of the at least one DCS and a maximum number Tmax of the plurality of time slots.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system using at least one digitally controllable scatterer (DCS) and a space-time DCS code. The present disclosure provides a wireless communication system, a corresponding method, and a computer program product. Background Art

[0002] In currently deployed wireless communication systems, the wireless channel cannot be controlled, so wireless communication between a transmitter (TX) and a receiver (RX) is achieved through algorithms that adapt the TX and RX to given channel conditions. Recent research has proposed a new paradigm for wireless communication, in which large intelligent surfaces (LIS), also known as reconfigurable intelligent surfaces (RIS) or reflective intelligent surfaces (RIS), are introduced into the propagation environment in order to use them as digitally controllable scatterers (DCS), such that the channel is also controllable. The DCS supports modifying some propagation paths of the wireless channel, thus enabling the possibility of having a programmable wireless channel, where different algorithms can be used to adapt some propagation paths to improve wireless communication between the TX and the RX. Therefore, in this new paradigm, wireless communication between the TX and the RX is achieved through algorithms that not only program the TX and the RX, but also program the wireless channel to achieve the desired communication.

[0003] Most algorithms for channel programming using DCS require channel state information (CSI) for DCS configuration. However, since a part of the DCS has a large number of tunable elements, obtaining this CSI can be time-consuming and require a large overhead. Generally, the DCS is implemented using a large number (usually hundreds or thousands) of reflecting or scattering elements, which are placed on a surface as shown, for example Figure 1 The non-flat configuration (e.g., as shown in FIG. 2(a)) and the distributed configuration (e.g., as shown in FIG. 2(b)) of the DCS surface are also suitable for DCS implementation. Multiple DCSs can also be implemented by logically splitting one DCS into multiple DCSs through subsets of the scattering elements. Each scattering element provides the ability to control the phase of its scattered signal. By denoting the scattering elements of DCS d as the scattering elements of DCS d The scattering phases, making up the total S of the DCS d d Controllable scattering phase configuration matrix of S scattering elements Provides a method to control the S of the DCS d d ×S d Scattering pattern matrix F d (φ d ) to modify the propagation channel between the TX and the RX. The entire propagation channel h between the transmit antenna TXn and the receive antenna RXm via the DCS d m,d,n Is the TX-to-DCS channel (denoted by ), the DCS d-to-RX channel (denoted by ), and the scattering pattern F d (φ d ) function, and is shown by formula (1):

[0004]

[0005] Where the superscript Indicates transpose. Figure 3 Shows an exemplary channel from TXn to DCS d An exemplary channel from DCS d to RXm And the exemplary channel h between the transmit antenna TXn and the receive antenna RXm via the DCS d m,d,n .

[0006] Based on the knowledge of the channel components And Or functions of these components, to configure the DCS scattering phase φ d Has the following problems:

[0007] · Need to calculate large matrices. The channel matrices And Are both of size S d ×1, so these matrices can be quite large because their size depends on the number S of scattering elements of the DCS d , as mentioned above, is usually quite large. Larger channel matrices make channel estimation complex. For simplicity, usually only the cascaded channel Is estimated, however, this cascaded channel has S d Elements, so it is also a large channel matrix. Simplifications have been proposed, where only the And Statistics are estimated to support channel estimation on a slower time scale. Nevertheless, the size of the calculated statistical CSI matrix is still a function of S d .

[0008] · Feedback is required. DCSs are envisioned as low-capability devices; thus, they should not include RF chains or include only a limited number of RF chains. Therefore, channel estimation cannot be performed on DCSs and is typically performed on the RX. When the DCS phase φ d is designed to be a function of the measured channel and then configuring the DCS phase requires feedback of the channel or the desired configuration φ d to the DCS. If CSI in the form of exchanged channels and is considered, due to the size of the channel matrix, this would result in a large feedback overhead. If only φ d is fed back, the overhead is still large because the size of φ d also depends on the number of scattering elements S d . Algorithms have been proposed to reduce the feedback overhead through successive refinement algorithms, but these algorithms suffer from the need for multiple rounds of pilots, channel estimation, and feedback. Even if the amount of feedback can be reduced by using codebooks, in scenarios with short channel coherence times, the delay of the feedback information will degrade the system performance.

[0009] Although the benefits of DCSs for improving communication (e.g., improving coverage) have been demonstrated, most of the proposed algorithms suffer from the above two problems, namely the complexity of CSI acquisition and feedback.

[0010] A scheme has been proposed for large CSI requirements and feedback overhead, and this scheme uses a random configuration of the DCS phase φ d . Due to the random design of φ d , no CSI is required at the DCS for phase configuration. In addition, the random phase φ d can be generated at the DCS; thus, there is also no overhead for transmitting φ d to the DCS. The random phase at the DCS creates a random channel propagation path, which is opportunistically used in a manner similar to opportunistic beamforming. When only one DCS is used, the created channel variations can be limited, and thus, multiple DCSs may be required to generate a large enough channel variation to achieve the desired multi-user diversity through the DCS random channels. In addition, although CSI is not required for DCS phase configuration, a feedback delay is introduced because the channel link quality must be fed back from the user to the TX.

[0011] A random phase φ d for DCS configuration has been proposed that requires no CSI at the DCS and no transmission of φ d . However, randomly setting the phase without coordination between DCS elements may result in low energy at the receiver side.

[0012] Space Time Block Code (STBC) algorithms have been proposed to overcome the requirement of CSI estimation before data transmission. STBC is a code applied on the transmitter side that does not require CSI on the transmitter side. STBC is represented by a matrix that maps η complex symbols {s 1 , s 2 , …, s η} to a τ×μ matrix, i.e., a matrix consisting of τ rows and μ columns. Most known STBC matrices have been designed to encode η symbols over μ transmit antennas and τ time slots, where τ≥μ and η≤μ. An example of STBC is the Alamouti code, corresponding to the case of η = 2, τ = 2, μ = 2, as shown in Equation (2):

[0013]

[0014] A DCS with dedicated transmit antenna illumination using the Alamouti code has been proposed, where the transmit antenna transmits a carrier of a single sub - carrier (tone). The information symbols {s 1 , s 2} to be transmitted (via wires or a dedicated connection) are transmitted to the DCS and then used to configure the DCS phase φ d , such that the signal scattered by the DCS is the Alamouti - encoded carrier sub - carrier of the symbols {s 1 , s 2}. Although CSI is not required at the DCS, the DCS needs to know the information symbols to be transmitted, which still increases the control overhead of the DCS. In addition, only the propagation path via the DCS is used, so if there are other non - DCS propagation paths (i.e., direct paths), these paths are not considered. Moreover, since DCS scattering elements mainly provide phase control, symbols with a constant amplitude from the constellation can mainly be transmitted. The implementation cost of DCS elements that provide both amplitude and phase control may be higher. SUMMARY OF THE INVENTION

[0015] In view of this, the present disclosure aims to overcome the problems of large CSI requirements and feedback overhead of DCS algorithms. The aim is to provide a wireless communication system and method that use algorithms with reduced CSI knowledge and feedback requirements to achieve communication enhancement using one or more DCSs.

[0016] This aim and other aims are achieved by the present disclosure according to the technical solutions described in the independent claims. Advantageous implementation manners are further described in the dependent claims.

[0017] A first aspect of the present disclosure provides a wireless communication system, comprising: at least one transmitter for transmitting an encoded radio frequency signal to at least one receiver during a plurality of time slots; at least one digitally controllable scatterer (DCS), the DCS comprising a scattering surface, the scattering surface comprising a set of scattering elements, each scattering element having a controllable phase shift; a controller; at least one receiver for obtaining the encoded radio frequency signal transmitted by the at least one transmitter during the plurality of time slots by receiving. The controller is configured to: control the at least one transmitter to generate the encoded radio frequency signal during the plurality of time slots based on a space time DCS code (STDC); control the set of scattering elements of the at least one DCS during the plurality of time slots based on the STDC, wherein the encoded radio frequency signal transmitted by the at least one transmitter during the plurality of time slots propagates from the at least one transmitter to the at least one receiver through one or more propagation channels, the one or more propagation channels comprising one or more propagation channels via the at least one DCS and / or one or more direct propagation channels; wherein the STDC depends on the total number of the at least one DCS and the maximum number T of the plurality of time slots max 。

[0018] Therefore, the STDC defines the configuration of the at least one transmitter and the at least one DCS during the plurality of time slots.

[0019] This provides the advantages of the STDC for implementing DCS configuration, transmitter encoded signal generation, and receiver processing, without CSI feedback and without the need to estimate large channel matrices.

[0020] Further advantageously, the overhead of transmitting the STDC can also be reduced and the efficiency can be improved.

[0021] In one implementation of the first aspect, the STDC comprises an STDC matrix B, the STDC matrix B having dimensions T×D, where D is the total number of the at least one DCS, D≥1, and where T≤T max is the total number of the plurality of time slots.

[0022] In one implementation of the first aspect, the total number of the plurality of time slots satisfies T max ≥D, where the STDC matrix B is defined based on δ≤D complex values {β 1 ,β 2 ,…,β δ}, and the entries of row i of the matrix B belong to {±β 1 ,±β 2,…, ±β δ , 0} or wherein, is the complex conjugate of,

[0023] It should be noted that the STDC does not depend on the number of scattering elements of the at least one DCS. Therefore, the efficiency can be improved and a lower overhead can be obtained.

[0024] In one implementation of the first aspect, the code of each DCS among the at least one DCS d (d ∈ {1, 2, …, D}) is determined by the corresponding d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is denoted as B d .

[0025] This provides the advantage that the code of the at least one DCS can be easily determined by selecting the corresponding column of the STDC matrix B.

[0026] In one implementation of the first aspect, for time slot t i ∈ {t 1 , t 2 , …, t T}, the controller is used to determine that the encoded configuration of each DCS among the at least one DCS d (d ∈ {1, 2, …, D}) is B i,d F d (φ d ), F d (φ d ) is the scattering pattern of the at least one DCS d, φ d is the basic phase shift configuration matrix of the at least one DCS d, and B i,d represents the entry in the i-th row of the corresponding code B d .

[0027] This provides the following advantages: the encoded configuration of the at least one DCS can be a phase-shifted version of the scattering pattern F d (φ d ), where the phase shift is indicated by α d = B i,d . Therefore, when using the phase-shifted scattering pattern α d F d (φ d ), the coverage of the at least one DCS can be the same as when using F d (φ d ) because the phase shift α dThe scattering pattern in terms of the perceived energy at each point in space is not changed. This is beneficial because even when encoding is applied, the one or more propagation channels via the at least one DCS can remain fixed, and the main change is their overall phase. Thus, by using the STDC according to the present disclosure, at least one propagation path via the at least one DCS can be created, and the propagation path can remain fixed during the plurality of time slots. This facilitates channel estimation and signal combining at the at least one receiver.

[0028] Furthermore, the programming of the DCS according to the present disclosure has the following advantage: the information symbols are required only at the at least one transmitter, rather than at the at least one DCS. This is an important difference from the prior art that uses DCS to implement STBC Alamouti, where information symbols are required at the DCS for DCS programming, resulting in a large overhead for transmitting the information symbols to the at least one DCS.

[0029] In one implementation of the first aspect, for each time slot t i , t i ∈{t 1 , t 2 ,…, t T}, the at least one transmitter is further configured to transmit the information symbol x in the encoded radio frequency signal, where the encoded radio frequency signal includes a transformation of the information symbol x based on the STDC matrix B, and the transformation of the information symbol x includes: if the entry in the corresponding i-th row of the STDC matrix B belongs to {±β 1 , ±β 2 ,…, ±β δ , 0}, then the information symbol x at the time slot t i ; or if the entry in the corresponding i-th row of the STDC matrix B belongs to then the information symbol x at the time slot t i ; where, x * is the complex conjugate of the information symbol x. *

[0030] The proposed STDC can be applied to multiple independent single-antenna transmitters or can be applied to encoding using only one single-antenna transmitter. In a communication system with low-complexity devices, such as in Internet of Things (IoT) devices where STBC may not be achievable, the above is an ideal function where encoding is required on at least two transmit antennas.

[0031] Further advantageously, this can enable the symbols transmitted by the at least one transmitter to be taken from a constellation with varying amplitudes.

[0032] In one implementation of the first aspect, the at least one receiver is used to estimate one or more propagation channels via the at least one DCS, additionally or alternatively, one or more direct propagation channels.

[0033] In one implementation of the first aspect, for each time slot t i , t i ∈{t 1 , t 2 , …, t T}, the at least one receiver is further used to determine the information symbol x transmitted by the at least one transmitter based on the STDC, based on the received coded radio frequency signal, based on the estimated one or more propagation channels via the at least one DCS, additionally or alternatively, the estimated one or more direct propagation channels.

[0034] The estimation of the information symbol x by the at least one receiver may be based on, for example, diversity combining.

[0035] This provides the advantage that channel estimation may only be performed and required at the receiver; thus, feedback may not be required. In addition, the number of entries in the estimated channel matrix does not depend on the number S of DCS scattering elements d , and it is much smaller than S d .

[0036] In one implementation of the first aspect, one of the controller, the at least one transmitter, the at least one receiver, or the at least one DCS is further used to: determine the STDC matrix B; send the total number T of the plurality of time slots and the STDC matrix B to the controller and / or the at least one transmitter and / or the at least one receiver and / or the at least one DCS by signaling; or send the corresponding d-th column of the STDC matrix B and the total number T of the plurality of time slots to the at least one DCS d by signaling.

[0037] Since the STDC matrix B has only T×D elements, the overhead of signaling the STDC matrix B can be very small.

[0038] In addition, by sending the corresponding d-th column of the STDC matrix B to at least one DCS instead of the complete STDC matrix B, the overhead can be further reduced.

[0039] In one implementation of the first aspect, the STDC matrix B is determined offline, and the STDC matrix B, optionally or alternatively, the d-th column of the STDC matrix B is signaled before the at least one transmitter transmits the encoded RF signal.

[0040] This provides the advantage that overhead can be further reduced and efficiency can be improved.

[0041] In one implementation of the first aspect, the at least one transmitter is synchronized with the at least one DCS.

[0042] A second aspect of the present disclosure provides a wireless communication method, including: a controller controlling at least one transmitter to generate an encoded RF signal during a plurality of time slots based on a space-time DCS code (STDC); the controller controlling a set of scattering elements of at least one DCS during the plurality of time slots based on the STDC, the at least one DCS including a scattering surface, the scattering surface including the set of scattering elements, each scattering element having a controllable phase shift; the at least one transmitter transmitting the encoded RF signal to at least one receiver during the plurality of time slots; the at least one receiver obtaining the encoded RF signal transmitted by the at least one transmitter through reception during the plurality of time slots; wherein, the encoded RF signal transmitted by the at least one transmitter during the plurality of time slots propagates from the at least one transmitter to the at least one receiver through one or more propagation channels, the one or more propagation channels including one or more propagation channels via the at least one DCS and / or one or more direct propagation channels; wherein, the STDC depends on the total number of the at least one DCS and the maximum number T of the plurality of time slots max 。

[0043] Therefore, the STDC defines the configuration of the at least one transmitter and the at least one DCS during the plurality of time slots.

[0044] This provides the advantage of the STDC for implementing DCS configuration, transmitter encoded signal generation, and receiver processing, without the need for CSI feedback and without the need for estimation of a large channel matrix.

[0045] Further advantageously, the overhead of transmitting the STDC can also be reduced and efficiency can be improved.

[0046] In one implementation of the second aspect, the STDC includes an STDC matrix B, the STDC matrix B having dimensions T×D, where D is the total number of the at least one DCS, D≥1, and where T≤T max is the total number of the plurality of time slots.

[0047] In one implementation of the second aspect, the total number of the plurality of time slots satisfies T max ≥ D, where the STDC matrix B is defined based on δ ≤ D complex values {β 1 , β 2 , …, β δ}, and the entries in the i-th row of the matrix B belong to {±β 1 , ±β 2 , …, ±β δ}, 0} or where is the complex conjugate of

[0048] It should be noted that the STDC does not depend on the number of scattering elements of the at least one DCS. Therefore, the efficiency can be improved and a lower overhead can be obtained.

[0049] In one implementation of the second aspect, the code of each DCS in the at least one DCS d (d ∈ {1, 2, …, D}) is determined by the corresponding d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is denoted as B d .

[0050] This provides the advantage that the code of the at least one DCS can be easily determined by selecting the corresponding column of the STDC matrix B.

[0051] In one implementation of the second aspect, the controller controls a set of scattering elements of the at least one DCS based on the STDC during the plurality of time slots, including: for each time slot t i ∈ {t 1 , t 2 , …, t T}, the controller determines the encoded configuration of each DCS in the at least one DCS d (d ∈ {1, 2, …, D}) as B i,d F d (φ d ), where F d (φ d ) is the scattering pattern of the at least one DCS d, φ d is the basic phase shift configuration matrix of the at least one DCS d, and B i,d represents the entry in the i-th row of the corresponding code B d .

[0052] This provides the following advantages: the encoded configuration of the at least one DCS can be the scattering pattern Fd (φ d ) with a phase-shifted version, where the phase shift is given by α d = B i,d as shown. Thus, when using the phase-shifted scattering pattern α d F d (φ d ), the coverage of the at least one DCS can be the same as when using F d (φ d ) because the phase shift α d does not change the scattering pattern in terms of the energy perceived at each point in space. This is beneficial because even when applying coding, the one or more propagation channels via the at least one DCS can remain fixed, and the main change is their overall phase. Thus, by using the STDC according to the present disclosure, at least one propagation path via the at least one DCS can be created, and the propagation path can remain fixed during the plurality of time slots. This helps with channel estimation and signal combining at the at least one receiver.

[0053] Additionally, the programming of the DCS according to the present disclosure has the advantage that the information symbols are required only at the at least one transmitter, rather than at the at least one DCS. This is an important difference from the prior art that uses DCS to implement STBC Alamouti, where information symbols are required at the DCS for DCS programming, resulting in a large overhead for transmitting the information symbols to the at least one DCS.

[0054] In one implementation of the second aspect, the controller controls the at least one transmitter to generate an encoded radio frequency signal during a plurality of time slots based on the STDC, including: for each time slot t i , t i ∈ {t 1 , t 2 , …, t T}, the at least one transmitter transmits the information symbol x in the encoded radio frequency signal; wherein the encoded radio frequency signal includes a transformation of the information symbol x based on the STDC matrix B, and the transformation of the information symbol x includes: if the entry in the corresponding i-th row of the STDC matrix B belongs to {±β 1 , ±β 2 , …, ±β δ , 0}, then the information symbol x at the time slot t i ; or if the entry in the corresponding i-th row of the STDC matrix B belongs to then the information symbol x at the time slot t i , where x * , where, x *is the complex conjugate of the information symbol x.

[0055] The proposed STDC can be applied to multiple independent single-antenna transmitters or can be applied to encoding using only one single-antenna transmitter. In a communication system with low-complexity devices, such as IoT devices where STBC may not be achievable, encoding on at least two transmit antennas is required, and the above is an ideal function.

[0056] Further advantageously, this can enable the symbols transmitted by the at least one transmitter to be taken from a constellation with varying amplitudes.

[0057] In one implementation of the second aspect, the method further includes: the at least one receiver estimates the one or more propagation channels via the at least one DCS, additionally or alternatively, the one or more direct propagation channels.

[0058] In one implementation of the second aspect, the method further includes: for each time slot t i , t i ∈{t 1 , t 2 ,…, t T}, the at least one receiver determines the information symbol x transmitted by the at least one transmitter based on the STDC, based on the received encoded radio frequency signal, based on the estimated one or more propagation channels via the at least one DCS, additionally or alternatively, the estimated one or more direct propagation channels.

[0059] The estimation of the information symbol x by the at least one receiver can be based on, for example, diversity combining.

[0060] This provides the advantage that channel estimation may only be performed and required at the receiver; thus, feedback may not be needed. In addition, the number of entries in the estimated channel matrix does not depend on the number S of DCS scattering elements d , and it is much smaller than S d .

[0061] In one implementation of the second aspect, the method further includes: one of the controller, the at least one transmitter, the at least one receiver, or the at least one DCS determines the STDC matrix B. Further, the method includes: the at least one transmitter, the at least one receiver, or the at least one DCS sends the total number T of the plurality of time slots and the STDC matrix B to the controller and / or the at least one transmitter and / or the at least one receiver and / or the at least one DCS by signaling, or sends the corresponding d-th column of the STDC matrix B and the total number T of the plurality of time slots to the at least one DCS d by signaling.

[0062] Since the STDC matrix B has only T×D elements, the overhead of sending the STDC matrix B by signaling can be very small.

[0063] In addition, by sending the corresponding d-th column of the STDC matrix B to at least one DCS instead of the complete STDC matrix B, the overhead can be further reduced.

[0064] In one implementation of the second aspect, the method further includes: determining the STDC matrix B offline, and before the at least one transmitter sends the encoded radio frequency signal, sending the STDC matrix B by signaling, additionally or alternatively sending the d-th column of the STDC matrix B.

[0065] This provides the advantages of further reducing overhead and improving efficiency.

[0066] In one implementation of the second aspect, the method further includes: the at least one transmitter and the at least one DCS are synchronized.

[0067] The method according to the second aspect includes the features of the corresponding implementation of the wireless communication system of the first aspect.

[0068] A third aspect of the present disclosure provides a computer program product, including program code, which when implemented on a processor, is used to execute the method according to the second aspect or its implementation.

[0069] The computer program product according to the third aspect includes the features of the corresponding implementation of the method of the second aspect.

[0070] The method according to the second aspect and the computer program product according to the third aspect and their implementations provide the same advantages and effects as those described above for the wireless communication system of the first aspect and its corresponding implementations.

[0071] The technical solution according to the present disclosure can provide the following advantages:

[0072] · Diversity combining of different channel propagation paths can be achieved even in a scenario where there is only a single antenna on both the transmitter and receiver sides.

[0073] · The coding applied at the at least one DCS is independent of the transmitted information symbols.

[0074] · Greater flexibility can be achieved in the channel types generated using DCS.

[0075] · No feedback is required.

[0076] It should be noted that all devices, elements, units, and modules described in this application can be implemented in software or hardware elements or any combination thereof. The steps performed by the various entities described in this application and the functions to be performed by the various entities described are intended to refer to the respective entities for performing the respective steps and functions. Even in the description of the following specific embodiments, where the specific functions or steps to be performed by external entities are not reflected in the description of the specific detailed elements of the entity performing the specific step or function, those skilled in the art should understand that these methods and functions can be implemented in the corresponding software or hardware elements or any type of combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In conjunction with the accompanying drawings, the above aspects and their implementation manners will be elaborated in the description of the following specific embodiments, where:

[0078] Figure 1 An example of DCS is shown;

[0079] FIG. 2(a) and FIG. 2(b) show an exemplary configuration of a non-flat DCS scattering surface and an exemplary configuration of a distributed DCS scattering surface;

[0080] Figure 3 An exemplary signal propagated from a transmitter to a receiver via DCS through a propagation channel is shown, where the propagation channel depends on the channel from the transmitter to the DCS, the channel from the DCS to the receiver, and the scattering pattern of the DCS;

[0081] Figure 4 A schematic diagram of a wireless communication system provided by the present disclosure is shown;

[0082] Figure 5 An exemplary flowchart for generating a space-time DCS code provided by the present disclosure is shown;

[0083] Figure 6 A schematic diagram of an example of a wireless communication system provided by the present disclosure is shown;

[0084] Figure 7A schematic diagram showing an example of a wireless communication system provided by the present disclosure;

[0085] FIG. 8(a) and FIG. 8(b) show schematic diagrams of an example of a wireless communication system provided by the present disclosure;

[0086] Figure 9 A schematic diagram of an example of a wireless communication system provided by the present disclosure;

[0087] Figure 10 Shows an example of the exchanged information between a controller, a transmitter, two DCSs, and a receiver provided by the present disclosure;

[0088] Figure 11 Shows another example of the exchanged information between a controller, a transmitter, two DCSs, and a receiver provided by the present disclosure;

[0089] Figure 12 Shows an example of the exchanged information between a controller, a transmitter, D DCSs, and a receiver provided by the present disclosure;

[0090] FIG. 13(a) and FIG. 13(b) show examples of time slots for the case of transmitting four information symbols in a wireless communication system provided by the present disclosure;

[0091] Figure 14 Shows a wireless communication method provided by the present disclosure. Detailed implementation

[0092] Figure 4 Shows an exemplary embodiment of a wireless communication system 100 according to the present disclosure. The wireless communication system 100 includes at least one transmitter 102 for transmitting an encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116. The system 100 also includes at least one DCS 106 having a scattering surface 107. The scattering surface 107 includes a plurality of scattering elements 106, each scattering element 106 having a controllable phase shift. The system 100 also includes a controller 110 and at least one receiver 104, and the at least one receiver 104 is used to obtain the encoded radio frequency signal transmitted by the at least one transmitter 102 through reception during the plurality of time slots 116.

[0093] The controller 110 is used to control at least one transmitter 102 to generate an encoded radio frequency signal during a plurality of time slots 116 based on a space time DCS code (STDC) 112.

[0094] In addition, the controller 110 is used to control a set of scattering elements 108 of at least one DCS 106 during a plurality of time slots 116 based on the STDC 112. Therefore, the scattering elements 108 of the scattering surface 107 of the DCS 106 scatter the encoded signal transmitted by at least one transmitter 102 in a controlled manner based on the encoded STDC 112. It should be noted that since the STDC 112 does not depend on the number of scattering elements 108 of each DCS in at least one DCS, efficiency and low overhead are obtained.

[0095] The STDC 112 depends on the total number of at least one DCS 106 and the maximum number of a plurality of time slots 116, denoted as T max .

[0096] The encoded radio frequency signal transmitted by at least one transmitter 102 during a plurality of time slots 116 propagates from at least one transmitter 102 to at least one receiver 104 through one or more propagation channels 114. The one or more propagation channels 114 include one or more propagation channels via at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 include one or more direct propagation channels. That is, the one or more propagation channels 114 include one or more propagation channels between at least one transmitter 102 and at least one receiver 102 via at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 include one or more direct propagation channels between at least one transmitter 102 and at least one receiver. For example, in the case where the direct propagation channel between at least one transmitter 102 and at least one receiver is blocked, the one or more propagation channels 114 may not include the direct propagation channel between at least one transmitter 102 and at least one receiver.

[0097] The STDC 112 includes an STDC matrix b. The STDC matrix b has dimensions T×D, where D is the total number of at least one DCS 106, such that D≥1 and T≤T max is the total number of a plurality of time slots 116, and the maximum number of the plurality of time slots 116 is less than or equal to the total number T of the DCS 106 max ≥D.

[0098] The STDC matrix B is defined based on δ complex values {β 1 ,β 2 ,…,β δ}, and the number of the complex values is less than or equal to the total number of DCS 106, that is, δ≤D. The entries of the i-th row of the STDC matrix B belong to {±β 1 ,±β 2 ,…,±β δ ,0} or where is the complex conjugate of

[0099] The STDC matrix B can be derived from a conventional STBC matrix. Figure 5 An exemplary flowchart for generating the STDC matrix B in accordance with the present disclosure is shown.

[0100] In step S502, the flowchart may take as input the total number D of DCSs and the maximum number T of time slots 106 available for STDC max ≥ D.

[0101] Then, in step S504, an STBC matrix B that maps δ ≤ D complex values {β 1 , β 2 , …, β δ} to the T × D matrix B may be selected such that T ≤ T max . The matrix B may be selected such that the entries of any row i of B belong to {±β 1 , ±β 2 , …, ±β δ , 0} or but not both, where is the complex conjugate of This constraint is related to the fact that the effect of the common scattering phase shift of all the scattering elements 108 of the DCS 106 affects the overall phase shift of the entire signal scattered thereby, as described later in the present disclosure.

[0102] In step S506, the STDC matrix B may be determined by assigning the matrix selected in step S504 to the STDC matrix B. Figure 5 The exemplary flowchart of

[0103] Reference Figure 4 , the code of each DCS in at least one DCS d (d ∈ {1, 2, …, D}) 106 is determined by the corresponding d-th column of the STDC matrix B. The d-th column of the STDC matrix B is denoted as B d , and may also be referred to as the coding vector of the DCS d 106.

[0104] That is, for the total number of D DCSs 106, the code of the d-th DCS 106 (hereinafter may be referred to as DCS d in the present disclosure) (d ∈ {1, 2, …, D}) is specified by the d-th column of the STDC matrix B. Thus, a given DCS d 106 only needs to know the corresponding column d of B.

[0105] Then, for each time slot among the plurality of time slots 116, t i ∈ {t1 , t 2 , …, t T}, and the controller 110 is configured to determine the encoded configuration of each DCS in at least one DCS 106d (d ∈ {1, 2, …, D}) as B i,d F d (φ d ), where F d (φ d ) is the scattering pattern of at least one DCS d 106, φ d is the basic phase shift configuration matrix of at least one DCS d 106, and B i,d represents the entry in the i-th row of the corresponding code B d , that is, B i,d is the entry in the i-th row and the d-th column of the STDC matrix B.

[0106] During the plurality of time slots 116, when controlling a set of scattering elements 108 of at least one DCS 106 based on the STDC 112, the controller 110 can control at least one DCS 106d to select the d-th column of the STDC matrix B and further determine the above-mentioned encoded configuration. Additionally or alternatively, the controller 110 can control at least one DCS 106 during the plurality of time slots 116 to apply the determined encoded configuration.

[0107] The basic phase shift configuration matrix of at least one DCS d 106φ d can be locally determined at the corresponding DCS d 106. Thus, each DCS d 106 can independently and in a non-coordinated manner determine φ d , without signaling requirements. Alternatively, the controller can be used to determine φ d for each DCS in DCS d 106, and can send each φ d to each DCS d106 by signaling.

[0108] During the time slot t i , the encoded configuration of each DCS in at least one DCS 106d takes the form B i,d F d (φ d ) = α d F d (φ d ), that is, the encoded configuration of each DCS in at least one DCS 106d is a scaled version of the scattering pattern F d (φ d ), where the scaling is indicated by α d . When the entries of the STDC matrix B are all unit magnitudes, then α d fd (φ d ) when the coverage of at least one DCS d106 is the same as that when using F d (φ d ) because the scaled scattering pattern F d (φ d ) has a complex scalar α d that is a complex scalar of unit magnitude, so scaling α d corresponds to applying a phase shift to the scattering pattern F d (φ d ). Rotating the scattering pattern F d (φ d ) by a phase shift does not change the scattering pattern in terms of the energy perceived at each point in space, i.e., the size of the scattering pattern of at least one DCS106 does not change. This is beneficial because even when applying coding, one or more propagation channels via at least one DCS106 can remain fixed, and the only change is their overall phase (offset ∠(α d )). Therefore, by using the STDC 112 according to the present disclosure, at least one propagation path via at least one DCS106 remains fixed during multiple time slots 116 until the phase shift, which helps with channel estimation and signal combination at at least one receiver 104.

[0109] The basic phase shift configuration matrix φ d of each DCS in at least one DCS106 can be determined in a flexible manner, and thus F d (φ d ), because the coding can be applied as an overall scaling defined by α d on top of the scattering pattern. In other words, the coding according to the present disclosure is applied on top of any given scattering pattern F d (φ d ); thus, the STDC 112 provides more flexibility than traditional coding, where the code applies a phase shift pattern φ d that is updated throughout the coding process, and thus applies a changing scattering pattern F d (φ d ), and as a result, the scattering pattern changes throughout the coding time slot.

[0110] Using Equation (1), when using the scattering pattern α d F d (φ d ), the propagation channel via DCS d 106 from the transmit antenna (referred to as transmit antenna n) of at least one transmitter 102 to the receive antenna (referred to as receive antenna m) of at least one receiver 104 can be written as shown in Equation (3):

[0111]

[0112] Since according to the present disclosure, STDC 112 can only change α d , it can be noted from Equation (3) that encoding results in the scaling of the underlying channel or the basic channel h m,d,n , and the channel itself remains fixed during time slot 116T. Figure 4 Illustrated is the propagation channel 114 from at least one transmitter 102 to at least one receiver 104 via at least one DCS 106 given by g in Equation (3) when at least one DCS d106 uses the scattering pattern α d F d (φ d ). m,d,n

[0113] In Figure 4 the exemplary embodiment, for each time slot 116t i , t i ∈{t 1 , t 2 , …, t T}, the transmit antenna n of at least one transmitter 102 is also used to transmit the information symbol x in the encoded radio frequency signal, where the encoded radio frequency signal includes the transformation of the information symbol x based on the STDC matrix B.

[0114] The transformation of the information symbol x can generally be expressed as f TX (x, B, t i ), including: if the entry in the corresponding i-th row of the STDC matrix B belongs to {±β 1 , ±β 2 , …, ±β δ , 0}, then the information symbol x at time slot 116t i ; or if the entry in the corresponding i-th row of the STDC matrix B belongs to then the information symbol x at time slot 116t i , where x * is the complex conjugate of the information symbol x. *

[0115] The information symbol x to be transmitted by the transmit antenna n of at least one transmitter 102 only needs to be known at at least one transmitter 102 and does not need to be known by at least one DCS 106. Therefore, the wireless communication system 100 can reduce the overhead requirements. This is contrary to the prior art, where the information symbol needs to be known at at least one DCS 106.

[0116] Each transmitter in at least one transmitter 102 may include a single transmit antenna. Alternatively, each transmitter in at least one transmitter 102 may include multiple transmit antennas, and each transmit antenna may be used to transmit different information symbols based on STDC112 during T time slots. In other words, in the case where at least one transmitter 102 may include multiple transmit antennas, the transmission from each transmit antenna can be performed independently at each transmit antenna. Therefore, each transmit antenna can be used to transmit an independent information symbol x by encoding its corresponding information symbol x over T time slots 116 using STDC 112 as described above.

[0117] In this way, the STDC 112 according to the present disclosure can be a code for multiple independent single-antenna transmitters, or a code for multiple independent multi-antenna transmitters, and can also be applied to encode a single transmitter using only multiple antennas, or a single transmitter using only a single antenna. Encoding a single transmitter using only a single antenna is an ideal feature in a communication system with low-complexity devices, such as IoT devices where STBC may not be achievable because STBC requires encoding on at least two transmit antennas. In other words, STDC 112 can utilize the advantages of space-time diversity by encoding one or more propagation channels via one or more DCSs rather than encoding symbols on multiple transmit antennas.

[0118] Further advantageously, in Figure 4 an exemplary embodiment of the wireless communication system 100, even if the DCS element only provides phase shift control, the transmitted symbol x can be taken from any variable amplitude constellation, such as QAM with any number of constellation points (e.g., 4-QAM, 8-QAM, 16-QAM), or can be taken from a PSK constellation. In contrast, in a conventional Alamouti design with DCS, when the DCS element only provides phase shift control, the symbol must be of constant amplitude and is thus limited to a PSK constellation (e.g., 4-PSK, 8-PSK, 16-PSK), which has worse performance than a QAM constellation.

[0119] See Figure 4 , at least one transmitter 102 and at least one DCS 106 are synchronized. Synchronization between at least one transmitter 102 and at least one DCS 106 can be achieved, for example, by using a GPS signal. GPS-based synchronization is used in 5G to synchronize evolved Node B (eNB).

[0120] In Figure 4In an exemplary embodiment, at least one receiver 104 is used to estimate one or more propagation channels via at least one DCS 106 between at least one transmitter and at least one receiver 104 and / or one or more direct propagation channels between at least one transmitter 102 and at least one receiver 104.

[0121] Using the scattering pattern α d F d (φ d ) of one or more propagation channels g via at least one DCS d 106 m,d,n As shown in Equation (3). One or more direct propagation channels h 0 may be propagation channels generated by all paths from at least one transmitter 102 to at least one receiver 104 that do not propagate via at least one DCS 106. As described above, one or more propagation channels 114 may not include one or more direct propagation channels between at least one transmitter 102 and at least one receiver 104. For example, in the case where the direct propagation channel is blocked, one or more direct propagation channels may not be estimated by at least one receiver 104.

[0122] In addition to the plurality of time slots 116, additional time slots or training time slots for training may also be employed. The additional time slots or training time slots can be used to transmit a training pilot p from at least one transmitter 102 to at least one receiver 104 for channel estimation in at least one receiver 104.

[0123] Then, for each time slot 116t i , t i ∈{t 1 , t 2 ,…, t T}, at least one receiver 104 is further used to determine the information symbol x transmitted by at least one transmitter 102 based on the STDC 112, based on the received encoded radio frequency signal, based on the estimated one or more propagation channels via at least one DCS 106 and / or the estimated one or more direct propagation channels.

[0124] That is, when estimating at least one propagation channel 114, at least one receiver 104 may continue to decode the received STDC encoded signal transmitted by the transmission antenna n of at least one transmitter 110 in order to obtain an estimate of each information symbol x transmitted by the transmission antenna n of at least one transmitter 102 or each transmission antenna.

[0125] Each receiver in at least one receiver 104 may include a single receiving antenna. Alternatively, one or more receivers in at least one receiver 104 may include multiple receiving antennas, and each receiving antenna may be used to obtain, by receiving, an encoded radio frequency signal transmitted by at least one transmitter 102 during the plurality of time slots 116.

[0126] The estimation of the information symbol x by at least one receiver 104 may be based on diversity combining using: the encoded radio frequency signals received by at least one receiving antenna of at least one receiver 104 during the total number T of the plurality of time slots 116, one or more estimated propagation channels via at least one DCS 106 and / or an estimated direct propagation channel and the STDC matrix B. The diversity combining may be based on known combining procedures designed for STBC communication. In the case of multiple receiving antennas, the diversity combining may be separately applied to each encoded radio frequency signal received by each receiving antenna respectively. Further, if multiple receiving antennas are juxtaposed or share a signal processing unit, the signals obtained from the multiple receiving antennas may be further combined, for example, further combined in a Maximum Ratio Combining (MRC) manner. Therefore, the STDC 112 according to the present disclosure used in combination with diversity combining may use one or more direct propagation paths and / or one or more propagation paths via at least one DCS 106 for simplified channel estimation and information symbol estimation at at least one receiver 104.

[0127] In this exemplary embodiment, the controller 110 is used to determine the STDC matrix B.

[0128] Since the encoded radio frequency signal generated by at least one transmitter 102 is based on the STDC matrix B, this matrix may need to be known to at least one transmitter 102. Further, the STDC matrix B may need to be known at at least one receiver 104 to decode the received encoded radio frequency signal. Further, the STDC matrix B, additionally or alternatively B d may need to be known to at least one DCS 106. Therefore, the controller is further used to signal the total number T of the plurality of time slots 116 and the STDC matrix B to at least one transmitter 102, at least one receiver 104, and at least one DCS 106. This incurs some overhead; however, since the STDC matrix B has only T×D elements, the overhead is small.

[0129] Additionally or alternatively, since each DCS in at least one DCS 106 only needs its corresponding code, the controller may be used to signal the corresponding d-th column Bd of the STDC matrix B to each DCS in the at least one DCS d 106 d, rather than the complete STDC matrix B, and the total number T of a plurality of time slots 116. Thereby further reducing the overhead.

[0130] The controller 110 can also be used to determine the STDC matrix B offline and can be used to signal the STDC matrix B to at least one transmitter 102, at least one receiver 104, and at least one DCS 106 before at least one transmitter 102 transmits an encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116. Additionally or alternatively, the d-th column of the STDC matrix B is transmitted.

[0131] In this way, the overhead can be further reduced and the efficiency of the wireless communication system 100 can be improved.

[0132] Alternatively, the controller 110, at least one transmitter 102, at least one receiver 104, and additionally or alternatively, at least one DCS 106 can be used to store one or more tables including one or more STDC matrices B. Then, the controller 110 can be used to signal a code identifier to at least one transmitter 102, at least one receiver 104, and at least one DCS 106. The code identifier can include information of the STDC matrix B that specifies one or more STDC matrices B in the table, and the STDC matrix will be used to generate an encoded radio frequency signal transmitted from at least one transmitter 102 to at least one receiver 104 during a plurality of time slots 116, control a set of scattering elements 108 of at least one DCS 106 during a plurality of time slots 116, and decode the encoded radio frequency signal acquired by at least one receiver 104 during a plurality of time slots 116. For example, the indication information can be implemented by an index, and the index can specify the STDC matrix B of one or more STDC matrices B in the table to be used. Therefore, the overhead of transmitting the STDC matrix B can be further reduced.

[0133] Alternatively, at least one transmitter 102 can be used to determine the STDC matrix B. In addition, at least one transmitter 102 can be used to signal the total number T of a plurality of time slots 116 and the STDC matrix B to the controller 110, at least one receiver 104, and at least one DCS 106. Additionally or alternatively, at least one transmitter 102 can be used to signal the corresponding d-th column of the STDC matrix B (rather than the complete STDC matrix B) and the total number T of a plurality of time slots 116 to each DCS in at least one DCS d 106.

[0134] At least one transmitter 102 can also be used to determine the STDC matrix B offline. Then, at least one transmitter 102 can be used to signal the STDC matrix B, additionally or alternatively, the d-th column of the STDC matrix B, to the controller 110, at least one receiver 104, and at least one DCS 106 before at least one transmitter 102 transmits the encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116.

[0135] Each device among the controller 110, at least one transmitter 102, at least one receiver 104, and additionally or alternatively, at least one DCS 106, can be used to store one or more tables including one or more STDC matrices B. Then, at least one transmitter 102 can be used to signal a code identifier to the controller 110, at least one receiver 104, and at least one DCS 106. The code identifier can include information of the STDC matrix B specifying one or more STDC matrices B in the table to be used. For example, the indication information can be implemented by an index that can specify the STDC matrix B of one or more STDC matrices B in the table to be used.

[0136] Alternatively, at least one DCS 106 can be used to determine the STDC matrix B. At least one DCS 106 can also be used to signal the total number T of a plurality of time slots 116 and the STDC matrix B to the controller 110, at least one transmitter 102, at least one receiver 104, and additionally or optionally, to other DCS d 106 of at least one DCS 106. Additionally or alternatively, at least one DCS 106 can be used to signal the corresponding d-th column (instead of the complete STDC matrix B) of the STDC matrix B and the total number T of a plurality of time slots 116 to other DCS d 106 in at least one DCS 106.

[0137] Furthermore, at least one DCS 106 can be used to determine the STDC matrix B offline. Then, at least one DCS 106 can be used to signal the STDC matrix B, additionally or alternatively, the d-th column of the STDC matrix B, to the controller 110, at least one transmitter 102, at least one receiver 104, and other DCS 106 of at least one DCS 106 before at least one transmitter 102 transmits the encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116.

[0138] Each device among the controller 110, at least one transmitter 102, at least one receiver 104, additionally or alternatively, at least one DCS 106, can be used to store one or more tables including one or more STDC matrices B. Then, at least one DCS 106 can be used to send a code identifier to other DCSs 106 of the controller 110, at least one transmitter 102, at least one receiver 104, and at least one DCS 106 via signaling. The code identifier can include information of the STDC matrix B that specifies one or more STDC matrices B in the table to be used. For example, the indication information can be implemented by an index that can specify the STDC matrix B of one or more STDC matrices B in the table to be used.

[0139] Alternatively, at least one receiver 104 can be used to determine the STDC matrix B. Additionally, at least one receiver 104 can be used to send the total number T of a plurality of time slots 116 and the STDC matrix B to the controller 110, at least one transmitter 102, and at least one DCS 106 via signaling. Additionally or alternatively, at least one receiver 104 can be used to send the corresponding d-th column of the STDC matrix B (instead of the complete STDC matrix B) and the total number T of a plurality of time slots 116 to at least one DCS d 106 via signaling.

[0140] At least one receiver 104 can also be used to determine the STDC matrix B offline. Then, at least one receiver 104 can be used to send the STDC matrix B, additionally or alternatively, the d-th column of the STDC matrix B to the controller 110, at least one transmitter 102, and at least one DCS 106 via signaling before at least one transmitter 102 sends an encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116.

[0141] Each device among the controller 110, at least one transmitter 102, at least one receiver 104, and / or at least one DCS 106 can be used to store one or more tables including one or more STDC matrices B. Then, at least one receiver 104 can be used to send a code identifier to the controller 110, at least one transmitter 102, and at least one DCS 106 via signaling. The code identifier can include information of the STDC matrix B that specifies one or more STDC matrices B in the table to be used. For example, the indication information can be implemented by an index that can specify the STDC matrix B of one or more STDC matrices B in the table to be used.

[0142] For example, the STDC 112 according to the present disclosure can be used to scale the DCS scattering pattern by a complex scalar. Given a scattering pattern F of DCS d of at least one DCS 106 having S d scattering elements 108d (φ d )'s conventional model, as shown, for example, in formula (4):

[0143]

[0144] Wherein, the basic phase shift configuration matrix of DCS d is is the scattering element of DCS d106 108's scattering phase, and represents the scattering element 108-induced scattering amplitude. For example, the amplitude is related to the radar cross section of the scattering element 108.

[0145] Given a complex scalar By applying the new phase matrix to the scattering element 108 of at least one DCS d 106, as shown in formula (5), and applying the new scaling of the scattering amplitude to the scattering element 108 of DCS d, as shown in formula (6), to obtain the scattering pattern F of DCS d 106 d (φ d ) scaled by α d ,

[0146]

[0147]

[0148] And

[0149]

[0150] Applying the phase in formula (5) and the amplitude scaling in formula (6) to the DCS element produces the new scattering pattern shown in formula (7):

[0151]

[0152] It can be observed from the above formula (7) that the new scattering pattern is the scattering pattern F after being scaled by the above-mentioned α d as above d (φ d ).

[0153] In another example, STDC 112 can be used to scale the DCS scattering pattern by the conjugate of a complex scalar. Given a complex scalar In a manner similar to the above formulas (5) and (6), but instead of adding the phase θ d to the basic phase shift configuration matrix φ d , instead, add the phase -θ as shown in formula (8)d , to obtain the scattering pattern F of the DCS d 106 d (φ d ) scaled

[0154]

[0155] Using the new phase described in Equation (8) and the new scaling defined in Equation (6) above, the newly obtained scattering pattern is as shown in Equation (9):

[0156]

[0157] This is the conjugate-scaled scattering pattern F of α d . d (φ d ).

[0158] In another example, the STDC 112 can be used to scale the DCS scattering pattern by the negative conjugate of a complex scalar. Given a complex scalar In a manner similar to Equations (5) and (6) above, but instead of adding the phase θ d to the basic phase shift configuration matrix φ d , add the phase -θ d +π as shown in Equation (10), to obtain the scattering pattern F of the DCS d 106 d (φ d ) scaled

[0159]

[0160] Using the new phase described in Equation (10) above and the new scaling defined in Equation (6), the newly obtained scattering pattern is as shown in Equation (11):

[0161]

[0162] This is the scattering pattern of at least one DCS d 106 F scaled by the negative conjugate of α d . d (φ d ).

[0163] The above examples of DCS pattern scaling consider the scaling of complex scalars, thus modifying the scattering amplitude and phase of the scattering cell elements 108 of at least one DCS 106. However, it is challenging to make the scattering elements 108 of at least one DCS 106 have controllable scattering amplitudes, so most known DCS configurations are for DCSs that only provide scattering phase control. In the case where only the scattering phase of the scattering elements 108 of at least one DCS 106 can be controlled, by only setting γd = 1 Apply the process described in the above example.

[0164] Figure 6 For Figure 4 FIG. 1 is a schematic diagram of an example of a wireless communication system 100 according to an exemplary embodiment shown. Identical elements have the same reference symbols. In this example, the wireless communication system 100 may include a controller 110, a transmitter 102 having one transmit antenna, a receiver having one receive antenna 104, and two DCSs 106-1, 106-2. Each of the DCSs 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each of the scattering surfaces 107-1, 107-2 may include a set of scattering elements 108-1, 108-2.

[0165] The controller 110 may be used to determine the STDC 112, that is, the controller 110 may be used to determine the STDC matrix B. In this example, the total number of DCSs is D = 2, and it can be considered that T max = 2 and δ = 2, satisfying the requirement of δ ≤ D. The well-known STBC matrix maps two complex values {β 1 , β δ＝2} to the T×D matrix B such that T ≤ T max is a 2×2 Alamouti STBC matrix as shown in Equation (12):

[0166]

[0167] This matrix B satisfies the following constraints: The entries in a given row belong to {±β 1 , ±β 2 , 0} or but not both. This is easily verified by inspection, since the entries in row 1 of the matrix B shown in Equation (12) are {β 1 , β 2} ∈ {±β 1 , ±β 2 , 0}, and the entries in row 2 of the matrix B are In this example, β 1 and β 2 are generally represented as scalar complex values, and the specific values of β 1 and β 2 are not specified.

[0168] Then, the controller 110 may be used to select the Alamouti matrix B of Equation (12) as the STDC matrix B.

[0169] In addition, the controller 110 can be used to signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 the total number T of the plurality of time slots 116 and the STDC matrix B. Alternatively, instead of the complete STDC matrix B, the controller 110 can signal to each DCS among the DCSs 106-1, 106-2 the corresponding d-th column of the STDC matrix B.

[0170] The controller 110 can be used to determine the STDC matrix B offline and can signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 the STDC matrix B, additionally or alternatively, the d-th column of the STDC matrix B, before the transmitter 102 transmits the encoded radio frequency signal to the receiver 104 during the plurality of time slots 116.

[0171] Alternatively, the controller 110, the transmitter 102, the receiver 104, additionally or alternatively, the DCSs 106-1, 106-2 can be used to store one or more tables including one or more STDC matrices B. Then, the controller 110 can be used to signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 a code identifier. The code identifier can include information of the STDC matrix B specifying one or more STDC matrices B in the table to be used. For example, the indication information can be implemented by an index that can specify the STDC matrix B of one or more STDC matrices B in the table to be used.

[0172] The controller 110 can also be used to determine the basic phase shift configuration matrices φ 1 , φ 2 for each of the DCSs 106-1, 106-2 respectively. The basic phase shift configuration matrices δ 1 , φ 2 can be obtained by the controller 110 in an arbitrary or random manner or from a predefined list or using any available prior knowledge about the DCSs 106-1, 106-2.

[0173] Then, the controller 110 can control a set of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 based on the STDC 112 during T = 2 time slots 116. That is, for each time slot 116t i ∈ {t 1 , t 2} in the T = 2 time slots, the controller 110 can be used to set the scattering pattern to be equal to B i,d F d (φ d ) = α d F d (φ d ), αd = B i,d , to determine the encoded configuration of DCS d (d = 1, 2), where B i,d is the entry in the i-th row and d-th column of matrix B as described above, and F d (φ d ) is the scattering pattern of each DCS d 106-1, 106-2.

[0174] Alternatively, the controller 110 can control each DCS 106-1, 106-2 to select the corresponding code B d and determine the corresponding encoded configuration.

[0175] For the STDC matrix B defined in formula (12), for time slot t 1 , the code for DCS d = 1 106-1 is determined by the first entry of the corresponding code B 1 , that is, the entry in the first row and first column of the STDC matrix B provided in formula (12) sets α 1 = β 1 ; thus, the controller 110 can be used to determine the encoded configuration of DCS d = 1 106-1 as B 1,1 F 1 (φ 1 ), equal to β 1 F 1 (φ 1 ). At time slot t 1 , the code for DCS d = 2 106-2 is determined by the first entry of the corresponding code B 2 , and the controller 110 can determine the encoded configuration of DCS d = 2 106-2 as B 1,2 F 2 (φ 2 ), equal to β 2 F 2 (φ 2 ), where β 2 is the first entry of the corresponding code B 2 , that is, the entry in the first row and second column of the STDC matrix B in formula (12) sets α 2 = β 2 .

[0176] In addition, for time slot t 2 , the code for DCS d = 1 106-1 is determined by the second entry of B 1 , the entry in the second row and first column in the STDC matrix B in formula (12) sets Thus, the encoded configuration or scattering pattern is Similarly, for time slot t2 , the code of DCS d = 2 106-2 is determined by the second entry of B 2 , and the entry in the second row and second column of the STDC matrix B in formula (12) is set and the encoded configuration or scattering pattern of DCS d = 2 106-2 is The encoded configurations obtained for each time slot 116 and each DCS 106-1, 106-2 are shown in Table 1.

[0177]

[0178] Table 1

[0179] In this example with a single transmitter 101 and a single receiver 104, each having a single antenna respectively, so n = 1 and m = 1, the one or more propagation channels via the two DCSs 106-1, 106-2 are represented as h based on formula (1) 1 = h 1,1,1 and h 2 = h 1,2,1 , and are defined as formula (13) and formula (14):

[0180]

[0181] Using formula (3), which is defined for a DCS d with a scattering pattern equal to α d F d (φ d ), the propagation channel obtained from at least one transmitter 102 n = 1 to at least one receiver 104 m = 1 via DCS d is g 1,d,1 = α d h 1,d,1 . In addition, for the sake of simplicity, g 1 is defined as g 1,1,1 = α 1 h 1,1,1 = α 1 h 1 and g 2 is defined as g 1,2,1 = α 2 h 1,2,1 = α 2 h 2 . The expressions of the propagation channels via each DCS 106-1, 106-2 are shown in Table 2.

[0182]

[0183] Table 2

[0184] As can be seen from Table 2, α dThe value varies as a function of STDC 112, which is specified by the δ ≤ D complex-valued {β 1 , β 2 , …, β δ} of the STDC matrix B. Thus, channel programming of STDC 112 using the controlled channel variations shown in Table 2 is provided.

[0185] Then, the controller 110 can be used to control the transmitter 102 to generate an encoded radio frequency signal based on STDC 112. That is, for each time slot 116t i , the transmitter 102 can be used to transmit the information symbol x in the encoded radio frequency signal. The encoded radio frequency signal can include a transformation of the information symbol x based on the STDC matrix B, f TX (x, B, t i ). For time slot t 1 , since the entries in the first row of the matrix B shown in Equation (12) are {β 1 , β 2} ∈ {±β 1 , ±β 2 , 0}, then the transmitter 102 can be used to transmit the symbol x in time slot t 1 . For time slot t 2 , since the entries in the second row of the matrix B are then the transmitter 102 can be used to transmit the symbol x * . The symbols transmitted in each time slot 116 are summarized in Table 3.

[0186]

[0187] Table 3

[0188] In the example of Figure 6 , the transmitter 102 can also be used to transmit the training pilot p during additional or training time slots based on STDC 112. In a case where the estimation of one or more propagation channels via at least one DCS and / or one or more direct propagation channels is not yet available at the receiver 104 side, the receiver 104 may require the training pilot p transmitted during the training time slots in order to estimate one or more propagation channels 114.

[0189] Table 4 shows the encoded signals transmitted by the transmitter 102, including additional time slots for transmitting the training pilot p for channel estimation and time slots t 1 and t 2 116 for transmitting the encoded signals (or the transformation of the information symbols transmitted by the transmitter 102) transmitted by the transmitter 102. For each α of the DCSs 106-1, 106-2 dThe values are also shown in Table 4. As described above, during two time slots 116t 1 、t 2 ,α d depends on the STDC matrix B. During additional time slots for training, the controller 110 can be used to control a set of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 by, for example, setting the value of α d in a predetermined manner. The resulting direct propagation channel (denoted as h 0 ) between the transmitter 102 and the receiver 104, the propagation channels h 1 and h 2 via the two DCSs 106-1, 106-2, and the encoded RF signals received by the receiver 104 are also included in Table 4.

[0190]

[0191] Table 4

[0192] The transmitted pilot p can be known at the receiver 104. Then, for each training time slot, the receiver 104 can be used to estimate one or more propagation channels via the DCSs 106-1, 106-2h 、h based on the received training pilot p and the received signals 1 、h 2 , additionally or alternatively, estimate one or more direct propagation channels h 0 . These channels are just scalars, so their estimation is easier compared to the estimation of channels whose size depends on the number of scattering elements 108-1, 108-2 of each DCS 106-1, 106-2, as described in the conventional algorithms using DCSs.

[0193] In addition, the receiver 104 can be used to determine the information symbol x transmitted by the transmitter 102 based on the STDC 112, based on the encoded RF signals received during the time slot 116, and based on one or more estimated propagation channels via at least one DCS 106, additionally or alternatively, one or more estimated direct propagation channels.

[0194] For this purpose, the receiver 104 can proceed as follows. The received signal vector y is constructed by superimposing the signals received in the first time slot, i.e., y t1 , and using the conjugate of the signals received in the second time slot, i.e., . The signals received in the second time slot are conjugate because the information symbols transmitted in the second time slot are as conjugate x *Sent. Following this approach, in the present disclosure, the received signal vector y can be expressed as provided in Equation (15):

[0195]

[0196] Since one or more propagation channels h 0 、h 1 and h 2 have been estimated by the receiver 104, the overall channel matrix H can be constructed as in Equation (16):

[0197]

[0198] The channel matrix H can be used to write the received signal vector as shown in Equation (17):

[0199]

[0200] Then, the combining matrix Q can be calculated as in Equation (18):

[0201]

[0202] where H * is used to represent the conjugate transpose of H, and by applying this matrix to the received signal vector y, Equation (19) is obtained:

[0203]

[0204] The diagonal terms in Equation (19) show that the received signals and the combined signals using the combining matrix Q shown in Equation (18) provide a diversity combination of the direct path between the transmitter 102 and the receiver 104 and the paths via the DCSs 106-1, 106-2 between the transmitter 102 and the receiver 104. The diagonal terms contribute to the coherent combination of the direct path and the paths via the DCSs 106-1, 106-2.

[0205] Since the STDC matrix B and its complex values β 1 and β 2 are known at the receiver 104, the receiver 104 can be used to construct the normalization matrix as shown in Equation (20):

[0206]

[0207] Using the received signal vector y, the combining matrix Q, and the normalization matrix N, the receiver 104 can obtain three initial estimates of the information symbol x transmitted by the transmitter 102 in the encoded radio frequency signal as shown in Equation (21)

[0208]

[0209] The three initial estimates can be combined together to obtain a final estimate of x as shown in Equation (22):

[0210]

[0211] where the scaling term z is shown in Equation (23):

[0212]

[0213] The noise term zx depends on the information symbol x and the scaling term z. Since the propagation channels h 0 、h 1 and h 2 can be independent and random, their combination in the expression for z in Equation (23) is expected to result in a variable with a zero-mean distribution as where is a Gaussian distribution with zero mean and variance v z , and the distribution will depend on the channel statistics and the combination of terms in Equation (23).

[0214] If the direct propagation channel h 0 is much weaker than the propagation channels via DCS106-1, 106-2, as is commonly assumed in DCS and as can be evaluated after channel estimation, then the receiver 104 can disregard the terms proportional to h 0 , and the combination matrix Q is simplified as shown in Equation (24):

[0215]

[0216] The normalization matrix takes the form of Equation (25):

[0217]

[0218] Therefore, the initial estimate is shown in Equation (26):

[0219]

[0220] The final estimate of the information symbol x is shown in Equation (27):

[0221]

[0222] where the term z is shown in Equation (28):

[0223]

[0224] In this case, since h0 is weak, and due to h 0 or its conjugate multiplying each term in Equation (28), then z shown in Equation (28) is also weak. In other words, the term zx is much smaller than x, which further facilitates improving the estimation of the information symbol x from Equation (27).

[0225] Optionally, additive white Gaussian noise (AWGN) that always exists in the received signal can be added to the received signal vector in Equation (15) to estimate the information symbol x. Thus, as described above, the process of combining with Q, normalizing using N, and combining the initial estimates to obtain the final estimate of x also takes into account an additional noise term having an amplitude smaller than x.

[0226] In this example, as described above, β 1 and β 2 are considered to have general complex values. The values of β 1 and β 2 can be assigned according to the capabilities or properties of at least one of DCS106-1, 106-2. For example, for a DCS that only provides scattering phase shift control, the values of β 1 and β 2 can be of unit magnitude. Given the specific values of β 1 and β 2 , further simplification or modification of channel estimation and the estimation of the information symbol x at the side of at least one receiver 104 can be achieved.

[0227] In another example, at least one receiver 104 can combine the received signals by processing the received signal vector y of Equation (15) via the pseudo-inverse operation of H (represented by ), and can further calculate the initial estimate as shown in Equation (29):

[0228]

[0229] Figure 7 is a schematic diagram of another example of the wireless communication system 100 for the exemplary embodiment shown in Figure 4 . Identical elements have the same reference symbols. In this example, the wireless communication system 100 can include a controller 110, a transmitter 102 having one transmit antenna, a receiver 104 having one receive antenna, and a single DCS106. The DCS106 can include a scattering surface 107, and the scattering surface 107 can include a set of scattering elements 108.

[0230] The controller 110 can be used to determine the STDC 112. That is, the controller 110 can be used to determine the STDC matrix B. In this example, the total number of DCSs is D = 1, and it can be considered that T max = 2 and δ = 2, which meet the requirement of δ ≤ D. The STDC matrix B can be based on the Alamouti STBC matrix in formula (12), and the value β 1 = β 2 = 1, and the second column is ignored, as shown in formula (30):

[0231]

[0232] Then, the controller 110 can be used to signal to the transmitter 102, the receiver 104, and the DCS the total number T of multiple time slots 116 and the STDC matrix B.

[0233] The controller 110 can be used to determine the STDC matrix B offline and can signal the STDC matrix B to the transmitter 102, the receiver 104, and the DCS 106 before the transmitter 102 transmits the encoded radio frequency signal to the receiver 104 during multiple time slots 116.

[0234] Alternatively, the controller 110, the transmitter 102, the receiver 104, additionally or alternatively, the DCS 106 can be used to store one or more tables including one or more STDC matrices B. Then, the controller 110 can be used to signal to the transmitter 102, the receiver 104, and the DCS 106 a code identifier. The code identifier can include information of the STDC matrix B in formula (30) for specifying one or more potential STDC matrices B stored in the lookup table to be used. For example, the indication information can be implemented by an index, which can specify the STDC matrix B in formula (30) of one or more STDC matrices B in the table to be used.

[0235] The controller 110 can also be used to determine, for example, by any arbitrary or random manner, or from a predefined list or using any available prior knowledge of the DCS 106 or prior information about the propagation channel, the basic phase shift configuration matrix φ of the DCS 106 d .

[0236] Then, the controller 110 can control a set of scattering elements 108 of the DCS d = 1 106 during T = 2 time slots 116 based on the STDC 112. That is, for each time slot 116t in the T = 2 time slots i ∈ {t 1 , t 2}, the controller 110 can be used to set the scattering pattern to be equal to B i,d F d (φd ) = α d F d (φ d ), α d = B i,d , to determine the encoded configuration of DCS d = 1, where B i,d is the entry in the i-th row and d-th column of matrix B, and F d (φ d ) is the scattering pattern of DCS d 106.

[0237] Since the first (and only) column of matrix B in formula (30) is then at time slot t 1 the code setting α of the DCS 1 = 1, and the encoded configuration of DCS d = 1 106 is equal to the scattering pattern F 1 (φ 1 ). At time slot t 2 , α 1 = -1 is obtained. Therefore, the encoded configuration of the DCS is equal to -F 1 (φ 1 ). The scattering pattern via DCS106 and the propagation channel via DCS106 are as

[0238] shown in Table 5, where

[0239]

[0240] Table 5

[0241] Then, the controller 110 can be used to control the transmitter 102 to generate encoded radio frequency signals during multiple time slots 116 based on STDC 112. That is, for each time slot 116t 1 , t 2 , the transmitter 102 can be used to transmit the information symbol x in the encoded radio frequency signal, where the encoded radio frequency signal can include the transformation f TX (x, B, t i ).

[0242] For the STDC matrix B specified in formula (30), the transmitter 102 can be used to transmit the information symbol x at time slot 116t 1 because the entries in the first row of the STDC matrix B are {β 1} ∈ {±β 1 , ±β 2 , 0}, and the transmitter 102 can be used to transmit x 2 at time slot 116t * because the second row of the STDC matrix B is

[0243] Table 6 shows one or more direct propagation channels and one or more propagation channels via the DCS106 between the transmitter 102 and the receiver 104, as well as the transmitted and received signals for each time slot 116.

[0244]

[0245] Table 6

[0246] The transmitter 102 can use an additional time slot to transmit the pilot symbol p. The transmitted pilot can be known at the receiver 104. The receiver 104 can use the transmitted pilot together with the received signal and then can estimate one or more channels h via the DCS106 1 , additionally or alternatively, estimate one or more direct channels h 0 , as disclosed in the example above. Thus, compared to the estimation of a channel whose size depends on the number of scattering elements 108 of the DCS106, the estimation of the one or more estimated channels 114 being scalar is easier, as is the case in conventional algorithms using the DCS.

[0247] The received signal vector y after conjugating the received signal received by the receiver 104 after the second time slot t 2 is given by Equation (31):

[0248]

[0249] Then, the combining matrix Q can be easily calculated as in Equation (32):

[0250]

[0251] The matrix Q of Equation (32) can be applied to the received signal vector y, as shown in Equation (33):

[0252]

[0253] which, after normalization, gives two initial estimates of the transmitted symbol x shown in Equation (34) by multiplying all terms by

[0254]

[0255] The average of which is taken to obtain the final estimate of the symbol x shown in Equation (35):

[0256] ​

[0257] Optionally, AWGN can be added to the received signal vector in Equation (31), which includes the additional noise term in the above equation.

[0258] FIG. 8(a) is a schematic diagram of another example of a wireless communication system 100 based on Figure 4 the exemplary embodiment shown. The same elements have the same reference symbols. In this example, the wireless communication system 100 may include a controller 110, two transmitters 102-1, 102-2, two transmit antennas, i.e., n = 1, 2, each transmitter having a single transmit antenna, one receiver 104 having a single receiver antenna, i.e., m = 1, and two DCSs d = 1, 2 106-1, 106-2. Each DCS 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may include a set of scattering elements 108-1, 108-2.

[0259] The controller 110 can be used to determine the STDC 112. That is, the controller 110 can be used to determine the STDC matrix B. In this example, D = 2, and it can be considered that T max = 2 and δ = 2, meeting the requirement of δ ≤ D. The STDC matrix B can be selected as the Alamouti STBC matrix shown in Equation (12) above.

[0260] Then, the controller 110 can be used to send, via signaling, the total number T of multiple time slots 116 and the STDC matrix B to the transmitters 102-1, 102-2, the receiver 104, and the DCSs 106-1, 106-2. Additionally or alternatively, the controller 110 can send, via signaling, the corresponding d-th column of the STDC matrix B and the total number T of multiple time slots 116 to each DCS 106-1, 106-2.

[0261] The controller 110 can be used to determine the STDC matrix B offline, and can send, via signaling, the STDC matrix B to the transmitters 102-1, 102-2, the receiver 104, and the DCSs 106-1, 106-2, additionally or alternatively, the d-th column of the STDC matrix B, before each transmitter 102-1, 102-2 sends an encoded radio frequency signal to the receiver 104 during multiple time slots 116.

[0262] Alternatively, the controller 110, transmitters 102-1, 102-2, receiver 104, additionally or alternatively, DCSs 106-1, 106-2 can be used to store one or more tables including one or more STDC matrices B. Then, the controller 110 can be used to signal to the transmitters 102-1, 102-2, receiver 104 and DCSs 106-1, 106-2 a code identifier. The code identifier can include information of the STDC matrix B provided in formula (12) for specifying one or more STDC matrices B stored in a lookup table to be used. For example, the indication information can be implemented by an index which can specify the STDC matrix B provided in formula (12) of one or more STDC matrices B in the table to be used.

[0263] The controller 110 can also be used to determine, for example, in an arbitrary or random manner, or from a predefined list or using any available prior knowledge of the DCSs 106-1, 106-2, the basic phase shift configuration matrix φ for each DCS d 102-1, 102-2 d 。

[0264] Then, the controller 110 can control a set of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 during T = 2 time slots 116 based on the STDC 112, as disclosed in the example above in Figure 6 Details are not described again.

[0265] The encoded configuration of each DCS 106-1, 106-2 is independent of the number of transmitters 102-1, 102-2 and transmit antennas, and is also independent of the information symbols transmitted by the transmitters 102-1, 102-2. The encoded configuration of each time slot 116 and each DCS 106-1, 106-2 is the same as that in the example of Figure 6 and is shown in Table 1 above.

[0266] In this example, since there are two single-antenna transmitters 102-1, 102-2 and two DCSs 106-1, 106-2, there can be a total of four propagation channels via the DCSs 106-1, 106-2 shown in formulas (36) to (43):

[0267]

[0268] and

[0269] g 1 =g 1,1,1 =α 1 h 1,1,1 =α 1 h 1 (40)

[0270] g 2 = g 1,2,1 = α 1 h 1,2,1 = α 1 h 2 (41)

[0271] g 3 = g 1,1,2 = α 1 h 1,1,2 = α 3 h 3 (42)

[0272] g 4 = g 1,2,2 = α 1 h 1,2,2 = α 4 h 4 (43)

[0273] Among them, formula (3) is used to obtain g 1 , g 2 , g 3 , g 4 , whose definitions are equal to α for the encoded configuration d F d (φ d ) of DCSd106-1, 106-2, the channel obtained via DCS d from the transmit antenna n of one of the transmitters 102-1 and 102-2 to the receive antenna m of the receiver 104 is g m,d,n = α d h m,d,n .

[0274] Table 7 shows one or more propagation channels from transmitters 102-1, 102-2 via DCS102-1, 102-2 for each time slot 116.

[0275]

[0276] Table 7

[0277] As can be seen from Table 7, the propagation channels g 1 , g 2 , g 3 , g 4 change as a function of the values of the STDC matrix B shown in formula (12), thus providing channel programming for STDC 112.

[0278] Then, the controller 110 can be used to control each of the transmitters 102-1, 102-2 to generate an encoded radio frequency signal during a plurality of time slots 116 based on the STDC 112. That is, for each time slot 116t i , each of the transmitters 102-1, 102-2 can be used to transmit an information symbol x in the encoded radio frequency signal, where the encoded radio frequency signal can include a transformation of the information symbol x based on the STDC matrix B, denoted as f TX (x, B, t i ).

[0279] The information symbols transmitted from each of the transmitters 102-1, 102-2 are denoted as x n , n = 1, 2. These two symbols x 1 and x 2 can be completely independent. Each of the transmitters 102-1, 102-2 can transmit the same information symbol x in the encoded radio frequency signal during two time slots 116t 1 and t 2 . n .

[0280] Using the STDC matrix B specified in Equation (12), for time slot t 1 , the transmit antenna n of transmitter 102-n can be used to transmit the symbol x n , because the entries in the first row of the STDC matrix B are {β 1 , β 2} ∈ {±β 1 , ±β 2 , 0}. For time slot t 2 , the transmit antenna n of transmitter 102-n can be used to transmit the symbol 2 in time slot t because the entries in the second row of the STDC matrix B are

[0281] Table 8 summarizes the symbols transmitted by transmitters 102-1, 102-2 for each time slot 116.

[0282]

[0283] Table 8

[0284] In the example of FIG. 8(a), transmitters 102-1, 102-2 can also be used to transmit training pilot p during additional or training time slots based on STDC 112. In the case where the estimation of one or more propagation channels via at least one DCS and / or one or more direct propagation channels is not yet available at the receiver 104 side, the receiver 104 may require the training pilot p transmitted during the training time slot in order to estimate one or more propagation channels 114.

[0285] Table 9 shows the encoded RF signals transmitted by transmitters 102-1, 102-2 for two time slots 116t 1 , t 2 which include additional time slots for transmitting the training pilot p. The values of α d for each DCS106-1, 106-2 are also shown in Table 9. In the two time slots t 1 and t 2 , the value of α d depends on the STDC matrix B. During the training time slot, the controller 110 can be used to control a set of scattering elements 108-1, 108-2 of DCSs 106-1, 106-2 by, for example, setting the value of α d in a predetermined manner. The resulting direct propagation channels between transmitters 102-1, 102-2 and receiver 104 are denoted as h 0,1 , h 0,2 , and the propagation channels via the two DCSs 106-1 106-2 are also shown in Table 9.

[0286]

[0287] Table 9

[0288] The transmitted pilot p can be known at the receiver 104. Then, for each training time slot, the receiver 104 can be used to estimate one or more propagation channels via DCSs 106-1, 106-2h and based on the received training pilot p and the received signal 1 , h 2 , h 3 , h 4 , and additionally or alternatively, estimate one or more direct propagation channels h 0,1 , h 0,2 . The propagation channels 114 are scalar, so their estimation is easier compared to the estimation of channels whose size depends on the number of scattering elements 108-1, 108-2 of each DCS 106-1, 106-2, as described in conventional algorithms using DCSs.

[0289] In addition, for each time slot 116t 1 、t 2 , the receiver 104 can be used to additionally or alternatively estimate the information symbol x transmitted by one of the transmitters 102-1, 102-2 based on the STDC 112, the received encoded radio frequency signal, and one or more estimated propagation channels via the DCSs 106-1, 106-2, and one or more directly estimated propagation channels n 。

[0290] To this end, the receiver 104 can proceed as follows. The received signal vector y is constructed by superimposing the signals received in the first time slot, i.e., and using the conjugate of the signal received in the second time slot, i.e., The signal received in the second time slot is conjugate because the information symbol transmitted in the second time slot is transmitted as conjugate and In this way, the received signal vector y can take the form of Equation (44):

[0291]

[0292] Since h 0,1 、h 0,2 、h 1 、h 2 、h 3 and h 4 have been estimated by the receiver 104, the entire channel matrix H can be constructed as shown in Equation (45):

[0293]

[0294] The channel matrix of Equation (45) can be used to write the received signal vector as shown in Equation (46):

[0295]

[0296] The combination matrix Q and the normalization matrix N can be calculated as shown in Equation (47) and Equation (48) respectively,

[0297] Q = H * (47)

[0298]

[0299] where H * denotes the conjugate transpose of H. Using the received signal vector y in Equation (44), the combination matrix Q in Equation (47), and the normalization matrix N in Equation (48), the transmitted symbol x 1Three initial estimates and the transmitted symbol x 2 Three initial estimates as shown in Equation (49):

[0300]

[0301] The three initial estimates can be combined together to obtain x as shown in Equation (50): 1 The final estimate of:

[0302]

[0303] Similarly, the three initial estimates can be combined to obtain the final estimate of x shown in Equation (51): 2 The final estimate of:

[0304]

[0305] Since the propagation channels h 0,1 , h 0,2 , h 1 , h 2 , h 3 and h 4 are independent random variables, the resulting noise terms z 1 and z 2 in Equations (50) and (51) are expected to be Gaussian random variables with zero-mean distributions, and it is expected that as the number of at least one transmitter in the wireless communication system 100 increases, the variances of these noise terms decrease, and the values of z 1 and z 2 become very close to their mean values, i.e., very close to zero. This can provide further advantages when the wireless communication system 100 can include multiple low-complexity transmitters, such as multiple independent IoT devices.

[0306] The adaptation for multiple-antenna transmitters follows directly the example of the two transmitters of Figure 8(a), as shown in Figure 8(b). Figure 8(b) shows an example of the wireless communication system 100 based on the exemplary embodiment shown in Figure 4 for the case of a single transmitter 102 with two transmit antennas. The same elements have the same reference symbols. Following the example of Figure 8(a), the same propagation channels as in Table 7 are obtained, the same symbols transmitted by each antenna as in Tables 8 and 9 are obtained, and the same received signals as in Table 9 are obtained. The signal processing at the receiver 104 is the same as that described with respect to Equations (44) to (51).

[0307] The extension to more than two transmitters follows directly from the example of the two transmitters 102-1, 102-2 in Fig. 8(a) and the multi-antenna transmitter in Fig. 8(b). Figure 9 shows a schematic diagram of another example of a wireless communication system 100 based on Figure 4 the exemplary embodiment shown. The same elements have the same reference symbols. In this example, the wireless communication system 100 may include a controller 110, a transmitter 102 with a single transmit antenna n = 1, a receiver 104 with a single receive antenna (i.e., m = 1), and three DCSs 106-1, 106-2, 106-3, i.e., d = 1, 2, 3. Each DCS 106-1, 106-2, 106-3 may include a scattering surface 107-1, 107-2, 107-3, and each scattering surface 107-1, 107-2, 107-3 may include a set of scattering elements 108-1, 108-2, 108-3.

[0308] The controller 110 may be used to determine the STDC 112. That is, the controller 110 may be used to determine the STDC matrix B. In this example, D = 3, and it can be considered that T max = 4 and δ = 3, meeting the requirement of δ ≤ D. Map the three complex values {β 1 , β 2 , β δ＝3} to the STBC matrix on the T×D matrix B such that T ≤ T max as shown in Equation (52):

[0309]

[0310] The matrix B shown in Equation (52) satisfies the constraint that the entries in a given row belong to {±β 1 , ±β 2 , ±β 3 , 0} or but not both. This can be easily verified by inspection. The quantities β 1 , β 2 and β 3 are typically reserved as scalar complex values.

[0311] In addition, the controller 110 may be used to signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, 106-3 the total number T of multiple time slots 116 and the STDC matrix B. Alternatively, instead of the complete STDC matrix B, the controller 110 may signal to each DCS 106-1, 106-2, 106-3 the corresponding d-th column of the STDC matrix B and the total number T of multiple time slots 116.

[0312] The controller 110 can be used to determine the STDC matrix B offline and can, prior to the transmitter 102 transmitting an encoded radio frequency signal to the receiver 104 during a plurality of time slots 116, signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, 106-3 the STDC matrix B in formula (52). Additionally or alternatively, the d-th column of the STDC matrix B can be transmitted.

[0313] Alternatively, the controller 110, the transmitter 102, the receiver 104, and additionally or alternatively, the DCSs 106-1, 106-2, 106-3 can be used to store one or more tables including one or more STDC matrices B. Then, the controller 110 can be used to signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, 106-3 a code identifier. The code identifier can include information for specifying the STDC matrix B in formula (52) of one or more STDC matrices B stored in a lookup table to be used. For example, the indication information can be implemented by an index that can specify the STDC matrix B in formula (52) of one or more STDC matrices B in the table to be used.

[0314] The controller 110 can also be used to determine a basic phase shift configuration matrix φ for each of the DCSs 106-1, 106-2, 106-3 1 , φ 2 , φ 3 . The basic phase shift configuration matrix φ 1 , φ 2 , φ 3 can be obtained by the controller 110 in an arbitrary or random manner or from a predefined list or using any available prior knowledge of the DCSs 106-1, 106-2, 106-3.

[0315] Then, the controller 110 can control a set of scattering elements 108-1, 108-2, 108-3 of the DCSs 106-1, 106-2, 106-3 based on the STDC 112 during T = 4 time slots 116. That is, for each time slot 116t i ∈{t 1 , t 2 , t 3 , t 4}, the controller 110 can be used to set the scattering pattern to be equal to B i,d F d (φ d ) = α d F d (φ d ), α d = B i,d, to determine the encoded configuration of DCS d (d = 1, 2, 3), where B i,d is the entry in the i-th row and the d-th column of the matrix B as described above, and F d (φ d ) is the scattering pattern of each DCS d 106-1, 106-2, 106-3.

[0316] The obtained encoded configuration for each time slot 116 and each DCS 106-1, 106-2, 106-3 is shown in Table 10.

[0317]

[0318] Table 10

[0319] A scattering pattern equal to zero (0) can be obtained by using a DCS surface whose scattering characteristics can be turned off, or by using a specific DCS configuration to minimize the energy scattered by the scattering elements, for example, known as minimizing the radar cross section in the context of radar.

[0320] In this example with a single antenna transmitter 102 and a single antenna receiver 104, thus n = 1 and m = 1, the one or more propagation channels via DCS 106-1, 106-2, 106-3 are denoted as h 1 = h 1,1,1 , h 2 = h 1,2,1 and h 3 = h 1,3,1 , based on formula (1) and shown by formulas (53) to (55):

[0321]

[0322] Using formula (3), which defines for a DCS d with a scattering pattern equal to α d F d (φ d ), the obtained propagation channel from the transmit antenna n = 1 to the receive antenna m = 1 via DCS d is g 1,d,1 = α d h 1,d,1 . In addition, for the sake of brevity, g 1 = g 1,1,1 = α 1 h 1,1,1 = α 1 h 1 = α 2 g 1,2,1 = α 2 h 1,2,1 = α 2 h 2 and g3 = g 1,3,1 = α 3 h 1,3,1 = α 3 h 3 The propagation channels through each of DCSs 106-1, 106-2, 106-3 are shown in Table 11.

[0323]

[0324] Table 11

[0325] The controller 110 can be used to control the transmitter 102 to generate an encoded radio frequency signal based on the STDC 112. That is, for each time slot 116t i , the transmitter 102 can be used to transmit the information symbol x in the encoded radio frequency signal. The encoded radio frequency signal can include a transformation of the information symbol x based on the STDC matrix B described in formula (52), denoted as f TX (x, B, t i ).

[0326] For time slot t i , if the entry in the i-th row of the STDC matrix B belongs to {±β 1 , ±β 2 , ±β 3 , 0}, then the transmitter 102 can be used to transmit the symbol x, otherwise, if the entry in the i-th row of the STDC matrix B belongs to then the transmitter 102 can be used to transmit the symbol x * . Therefore, based on the STDC matrix B shown in formula (52) of this example, the symbols transmitted by the transmitter for each time slot 116 are shown in Table 12.

[0327]

[0328] Table 12

[0329] In Figure 9 example, the transmitter 102 can also be used to transmit the training pilot p during additional or training time slots. In the case where the estimation of one or more propagation channels through at least one DCS and / or one or more direct propagation channels is not yet available at the receiver 104 side, the receiver 104 may require the training pilot p transmitted during additional or training time slots in order to estimate one or more propagation channels 114.

[0330] Table 13 shows the encoded signals transmitted by the transmitter 102, including the training time slots for transmitting the training pilot p for channel estimation, and including four time slots 116t 1 , t 2 , t3 and the signals transmitted during t 4 For each of DCS106-1, 106-2, 106-3, the value of α d is also shown in Table 13. As described above, during the four time slots 116t 1 , t 2 , t 3 , t 4 , the value of α d depends on the value of the STDC matrix B. During the training time slot 116, the controller 110 can be used to control a set of scattering elements 108-1, 108-2, 108-3 of DCS106-1, 106-2, 106-3 by, for example, setting the value of α d in a predetermined manner based on the STDC matrix B. The resulting direct propagation channel between the transmitter 102 and the receiver 104, the propagation channels via DCS106-1, 106-2, 106-3, and the encoded RF signals received by the receiver 104 for each time slot 116, as well as the training time slot, are also included in Table 13.

[0331]

[0332]

[0333] Table 13

[0334] The transmitted pilot p can be known at the receiver 104. Then, for each training time slot, the receiver 104 can be used to estimate one or more propagation channels via DCS106-1, 106-2, 106-3h and based on the received training pilot p and the received signal 1 , h 2 , h 3 . Additionally or alternatively, estimate one or more direct propagation channels h 0 . These channels are just scalars, so their estimation is easier compared to the estimation of channels whose size depends on the number of scattering elements 108-1, 108-2, 108-3 of each of DCS106-1, 106-2, 106-3, as described in the conventional algorithms using DCS.

[0335] In addition, the receiver 104 can be used to determine the information symbol x transmitted by the transmitter 102 based on the STDC 112, based on the encoded RF signals received during the time slot 116, and based on one or more estimated propagation channels via DCS106-1, 106-2, 106-3, and additionally or alternatively, one or more estimated direct propagation channels.

[0336] To this end, the receiver 104 can proceed as follows. Decoding the selected 4×3 STDC matrix B shown in Equation (52) involves using the signals received in the first time slot of multiple time slots 116, and also using the conjugates of the signals received in the following time slots and and In this way, the received signal vector y can be written as Equation (56):

[0337]

[0338] Since one or more propagation channels h 0 、h 1 and h 2 have been estimated by the receiver 104, the overall channel matrix H can be constructed as in Equation (57):

[0339]

[0340] The channel matrix H of Equation (57) can be used to write the received signal vector as shown in Equation (58):

[0341]

[0342] The combining matrix Q and the normalization matrix N can be easily calculated as shown in Equation (59) and Equation (60) respectively:

[0343]

[0344] Using the received signal vector y in Equation (58), the combining matrix Q in Equation (59), and the normalization matrix N in Equation (60), four initial estimates of the transmitted symbol x can be obtained as shown in Equation (61):

[0345]

[0346] The four initial estimates can be combined to obtain the final estimate of the transmitted symbol x, as shown in Equation (62):

[0347]

[0348] The noise term zx depends on the symbol x and the scaling term z. Since the channels h 0 、h 1 、h 2 and h 3 are independent and random, the resulting expression for z is expected to produce a random variable with a mean-zero distribution as where, is a mean-zero and variance-vz The Gaussian distribution depends on the channel statistics and the combination of terms in the result of term z. When more DCSs are mentioned, term z includes adding additional random terms; thus, the variance of z decreases, and the value of z is very close to the zero mean, that is, as the number of DCSs used increases, z will tend to zero faster. Using more DCSs requires using more time slots; however, since more than one independent transmitter may be included in the wireless communication system 100 and these transmitters can transmit simultaneously, this can compensate for the additional required time slots.

[0349] If the direct propagation channel h 0 is weak, as is generally considered in DCS and as can be evaluated after channel estimation, then the receiver 104 can ignore the terms proportional to h 0 and can calculate the combining matrix Q as in formula (63):

[0350]

[0351] The normalization matrix takes the form of formula (64):

[0352]

[0353] The values of β 1 , β 2 and β 3 in the STDC matrix B can be determined according to the capabilities or attributes of the DCSs 106-1, 106-2, 106-3. For example, for a DCS that only provides scattering phase shift control, the values of β 1 , β 2 and β 3 can be of the order of unity. Given the specific values of β 1 , β 2 and β 3 , further simplification or alternative implementations of channel estimation and the estimation of the information symbol x on the side of at least one receiver 104 can be achieved.

[0354] Alternatively, four initial estimates of the transmitted symbol x can be obtained by applying the pseudo-inverse of H in formula (57) to the received signal vector

[0355] Optionally, AWGN can be added to the received signal vector in formula (58) to estimate the information symbol x. Thus, as described above, the processing for combining with Q, normalizing with N, and combining the initial estimates to obtain the final estimate of x also takes into account additional noise terms with amplitudes smaller than x.

[0356] Figure 10 illustrates Figure 6An example of the signaling exchanged in the wireless communication system 100. Specifically, Figure 10 The example depicts a scenario in which the radio wireless communication system 100 may include a controller 110, a transmitter 102, a receiver 104, and two DCSs 106-1, 106-2. Each of the DCSs 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may include a set of scattering elements 108-1, 108-2. The transmitter 102 and the DCSs 106-1, 106-2 may be synchronized.

[0357] The controller 110 may be used to determine the STDC 112, that is, the controller 110 may be used to determine the STDC matrix B, for example, according to the Figure 5 flow chart shown above.

[0358] In this example, D = 2, and it can be considered that T max = 2 and δ = 2, as disclosed above for the Figure 6 example.

[0359] In addition, the controller 110 may be used to signal to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 the total number T = 2 of multiple time slots 116 and the STDC matrix B. Additionally, the controller 110 may determine training time slots for channel estimation and may signal the training time slots to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2.

[0360] The controller 110 may be used to determine the STDC matrix B offline and may signal the STDC matrix B to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 before the transmitter 102 transmits the encoded radio frequency signal to the receiver 104 during multiple time slots 116.

[0361] The controller 110 may also be used to control the transmitter 102 to generate an encoded radio frequency signal during T = 2 time slots 116 based on the STDC 112. That is, for each time slot 116t i , the transmitter 102 may be used to transmit the information symbol x in the encoded radio frequency signal. The encoded radio frequency signal may include a transformation of the information symbol x based on the STDC matrix B, denoted as f TX (x, B, t i ). Details of the encoded information symbols of the transmitter 102 are as disclosed above for the Figure 6 example and will not be repeated here.

[0362] In addition, the controller 110 can control a set of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 based on the STDC 112 during the T = 2 time slots 116. That is, for each time slot 116t i ∈{t 1 ,t 2}, the controller 110 can be used to determine the encoded configuration of each DCS 106-1, 106-2 by setting the scattering pattern to be equal to B i,d F d (φ d ) = α d F d (φ d ), α d = B i,d , d = 1, 2, where B i,d is the entry in the i-th row and the d-th column of the STDC matrix B as described above, and F d (φ d ) is the scattering pattern of each DCS d 106-1, 106-2.

[0363] Alternatively, the controller 110 can control each DCS 106-1, 106-2 to select the corresponding d-th column of the STDC matrix B and further determine its encoded configuration as described above. Additionally or alternatively, the controller 110 can control each DCS 106-1, 106-2 during multiple time slots 116 in order to apply the determined encoded configuration.

[0364] The encoded configuration of each DCS 106-1, 106-2 is the same as that of Figure 6 . Details are not elaborated here.

[0365] In addition, the transmitter 102 can be based on the STDC 112 to send a training pilot p to the receiver 104 during a training time slot, and the receiver can be used to estimate one or more propagation channels.

[0366] Then, the transmitter 102 can be used to send a symbol x at time slot t 1 and send a symbol x at time slot t 2 . * .

[0367] Then, the controller 110 may control the receiver 104 to obtain, by reception, the encoded radio frequency signal transmitted by the transmitter 102 during a plurality of time slots 116. Then, the receiver 104 may be used to determine the information symbol x transmitted by at least one transmitter 102 based on the STDC 112, based on the received encoded radio frequency signal, and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, additionally or alternatively, the estimated one or more direct propagation channels.

[0368] Figure 11 shows Figure 6 another example of the signaling exchanged in the wireless communication system 100. Figure 11 The example of Figure 10 is the same as the example of Figure 11 except that, in 1 , φ 2 , the controller 110 may also be used to determine the basic phase shift configuration matrices φ 1 , φ 2 for each of the DCSs 106-1, 106-2. Then, the controller 110 may be used to signal the basic phase shift configuration matrices φ

[0369] to each of the DCSs 106-1, 106-2. In addition, the controller 110 may be used to signal to each of the DCSs 106-1, 106-2 the respective d-th column of the STDC matrix B instead of the full matrix: the STDC matrix B.

[0369] The remaining exchanged signaling between the controller 110, the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 and their configurations are the same as the example of Figure 10 and will not be elaborated here.

[0370] Figure 12 shows an example of the signaling exchanged in the wireless communication system 100. Figure 12 The example of

[0371] depicts a scenario where the radio wireless communication system 100 may include a controller 110, one transmitter 102, one receiver 104, and D DCSs, exemplarily DCSs 106-1, 106-2, and 106-D. Each of the DCSs 106-1, 106-2, 106-D may include a scattering surface 107-1, 107-2, 107-D, and each of the scattering surfaces 107-1, 107-2, 107-D may include a set of scattering elements 108-1, 108-2, 108-D. The transmitter 102 and the DCSs 104-1, 104-2, 104-D may be synchronized.

[0371] The controller 110 may be used to determine the STDC 112, that is, the controller 110 may be used to determine the STDC matrix B, for example, according to the flowchart shown in Figure 5 disclosed above.

[0372] The controller 110 may be configured to determine the STDC matrix B offline, and may send the STDC matrix B to the transmitter 102 and the receiver 104 via signaling before the transmitter 102 sends the encoded RF signal to the receiver 104 during the plurality of time slots 116 .

[0373] In addition, the controller 110 can also be used to determine a basic phase shift configuration matrix φ for each DCS 106-1, 106-2, 106-D respectively. 1 ,φ 2 ……φ D Then, the controller 110 may be used to send a signal represented by f(φ) to each DCS 106-1, 106-2, 106-D via signaling. d ,B d )

[0374] This information f(φ d ,B d ) may include a method for specifying each time slot 116t 1 ,t 2 ……t T The basic phase shift configuration matrix φ d The information of the corresponding DCS d is configured in several states and times. For example, the information f(φ d ,B d ) may include a basic phase shift configuration matrix φ d and the corresponding code for each DCS 106-1, 106-2, 106-D, i.e. the corresponding d-th column of the STDC matrix B, denoted as B d Additionally or alternatively, the information f(φ d ,B d ) may include any other type of information that may facilitate achieving the desired configuration of each DCS 106 - 1 , 106 - 2 , 106 -D.

[0375] The controller 110 may be used to determine the information f(φ) offline. d ,B d ), and may then be sent to the corresponding DCS 106-1, 106-2, 106-D via signaling.

[0376] Alternatively, the controller 110 may send each piece of information f(φ) at a time. d ,B d ), or can be in each time slot 116t 1 ,t 2 ……t TEach message is sent, i.e., the controller 110 can be used to send each message f(φ) by signaling to each DCS 106-1, 106-2, 106-D when the configuration of each DCS 106-1, 106-2, 106-D needs to be updated d ,B d ).

[0377] In addition, the controller 110 can be used to send the total number T of multiple time slots 116 and the STDC matrix B to the transmitter 102 and the receiver 104 by signaling. Additionally, the controller 110 can determine the training time slots for channel estimation and can send the training time slots to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, 106-D by signaling.

[0378] Then, the controller 110 can be used to control a set of scattering elements 108-1, 108-2, 108-D of the DCSs 106-1, 106-2, 106-D during multiple time slots 116 based on the STDC 112. That is, for each time slot 116t i ∈{t 1 ,t 2 ,…,t T}, the controller 110 can be used to determine the encoded configuration of each DCS 106-1, 106-2, 106-D by setting the scattering pattern to be equal to B i,d F d (φ d ), d = 1, 2, …, D, where B i,d is the entry in the i-th row and the d-th column of the STDC matrix B, and F d (φ d ) is the scattering pattern of each DCS 106-1, 106-2, 106-D.

[0379] For example, at time slot t 1 , the encoded configuration of DCS d = 1 106-1 is equal to B 1,1 F 1 (φ 1 ), the encoded configuration of DCS d = 2 106-2 is equal to B 1,2 F 2 (φ 2 ), and is similar for each DCS d, as Figure 12 shown. At time slot t 2 , the encoded configuration of DCS d = 1 106-1 is equal to B 2,1 F 1 (φ 1 ), the encoded configuration of DCS d = 2 106-2 is equal to B 2,2 F2 (φ 2 ), and similarly, the encoded configuration of DSC D 106-D at time slot t T is equal to B T,D F 1 (φ D ).

[0380] Alternatively, the controller 110 may control each of DCSs 106-1, 106-2, 106-D to determine its encoded configuration.

[0381] Then, the controller 110 may control the transmitter 102 to generate an encoded radio frequency signal based on the STDC 112. Further, for each time slot 116t i ∈{t 1 ,t 2 ,…,t T}, the transmitter 102 may be used to transmit the information symbol x in the encoded radio frequency signal. The encoded radio frequency signal may include a transformation of the information symbol x based on the STDC matrix B, denoted as f TX (x,B,t i ).

[0382] The transformation f TX (x,B,t i ) may include: the information symbol x at time slot 116t 1 if the entry in the corresponding i-th row of the STDC matrix B belongs to {±β 2 ,±β δ ,…,±β i ,0}; or the information symbol x at time slot 116t if the entry in the corresponding i-th row of the STDC matrix B belongs to i then the information symbol x at time slot 116t * , where x * is the complex conjugate of the information symbol x.

[0383] Then, the transmitter 102 may be used to transmit the training pilot p to the receiver 104 during the training time slot 116, and the receiver 104 may be used to estimate one or more propagation channels.

[0384] The transmitter 102 may also be used to transmit the transformation of the information symbol f i ∈{t 1 ,t 2 ,…,t T} in each time slot 116t TX (x,B,t i ).

[0385] The controller 110 may then control the receiver 104 to acquire, by reception, the coded RF signal transmitted by the transmitter 102 during the plurality of time slots 116. The receiver may then be configured to determine, based on the STDC 112, the information symbol x transmitted by the at least one transmitter 102, based on the received coded RF signal and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, 106-D and / or the estimated one or more direct propagation channels.

[0386] The STDC 112 according to the present disclosure can be extended to the case where multiple information symbols are transmitted per time slot in a simple and flexible manner. 1 ,t 2 ,…,t T Each time slot 116t in i The duration of may be adapted to span the duration of one information symbol, as schematically shown in FIG13(a), or the duration of multiple information symbols (sometimes also represented as frames), as schematically shown in FIG13(a). FIG13(a) shows Figure 6 An example of a time slot 116 in a wireless communication system 100 for a case where four information symbols 116 are transmitted, an exemplary x 1 、x 2 、x 3 、x 4 , where each time slot 116 spans the duration of one information symbol. FIG13(b) shows Figure 6 An example of a time slot 116 in a wireless communication system 100 for a case where four information symbols 116 are transmitted, an exemplary x 1 、x 2 、x 3 、x 4 , where each time slot 116 spans the duration of a plurality of information symbols or a frame duration.

[0387] Figure 14 The wireless communication method 200 provided by the present disclosure is shown. The method 200 may be performed by the above-mentioned Figure 4 The wireless communication system 100 is executed.

[0388] The method 200 comprises step S202: the controller 110 controls at least one transmitter 102 to generate a coded radio frequency signal during a plurality of time slots 116 based on a space-time DCS code 112 (STDC), wherein the STDC 112 depends on the total number of at least one DCS 106 and the maximum number T of the plurality of time slots 116. max .

[0389] Method 200 further includes step S204: The controller 110 controls a set of scattering elements 108 of at least one DCS 106 based on the STDC 112 in a plurality of time slots 116. At least one DCS 106 includes a scattering surface 107, and the scattering surface 107 includes a set of scattering elements 108, and each scattering element 108 has a controllable phase shift.

[0390] In addition, method 200 includes step S206: At least one transmitter 102 transmits an encoded radio frequency signal to at least one receiver 104 during a plurality of time slots 116.

[0391] Method 200 further includes step S208: At least one receiver 104 obtains the encoded radio frequency signal transmitted by at least one transmitter 102 by receiving during a plurality of time slots 116.

[0392] The encoded radio frequency signal transmitted by at least one transmitter 102 during a plurality of time slots 116 propagates from at least one transmitter 102 to at least one receiver 104 through one or more propagation channels 114, where at least one propagation channel 114 includes one or more propagation channels via at least one DCS 106, additionally or alternatively, one or more direct propagation channels.

[0393] Method 200 may further include operations according to the above exemplary embodiments of the wireless communication system 100. Therefore, method 200 achieves the same advantages as the above wireless communication system 100.

[0394] The present disclosure also provides a computer program product, including program code, which when implemented on a processor, is used to execute Figure 14 The method 200 described above. The computer program may be included in a computer-readable medium of the computer program product. The computer-readable medium may basically include any memory, such as a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a flash memory, an electrically erasable programmable read-only memory (EEPROM), or a hard disk drive.

[0395] The computer program product may further include operations according to the above method 200. Therefore, the computer program product achieves the same advantages as method 200 and wireless communication system 100.

[0396] The present disclosure has been described in connection with various embodiments and implementations taken as examples. However, upon study of the drawings, the disclosure, and the independent claims, other variations can be understood and effected by those skilled in the art in practicing the claimed subject matter. In the claims as well as in the specification, the word "comprising" does not exclude other elements or steps, and "a" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage.

Claims

1. A wireless communication system (100), comprising: at least one transmitter (102) for transmitting an encoded radio frequency signal to at least one receiver (104) during a plurality of time slots (116); at least one digitally controllable scatterer DCS (106), the DCS including a scattering surface (107) including a set of scattering elements (108), each scattering element having a controllable phase shift; a controller (110) for: - controlling the at least one transmitter (102) to generate the encoded radio frequency signal during the plurality of time slots (116) based on a space-time DCS code STDC (112); - controlling the set of scattering elements (108) of the at least one DCS (106) during the plurality of time slots (116) based on the STDC (112); at least one receiver (104) for obtaining the encoded radio frequency signal transmitted by the at least one transmitter (102) by receiving during the plurality of time slots (116); wherein the encoded radio frequency signal transmitted by the at least one transmitter (102) during the plurality of time slots (116) propagates from the at least one transmitter (102) to the at least one receiver (104) through one or more propagation channels (114), the one or more propagation channels (114) including one or more propagation channels via the at least one DCS (106) and / or one or more direct propagation channels; Wherein, the STDC (112) depends on the total number of the at least one DCS (106) and the maximum number T of the plurality of time slots (116) max .

2. The wireless communication system (100) according to claim 1, wherein, The STDC (112) includes an STDC matrix B having dimensions T×D, where D is the total number of said at least one DCS (106), D≥1, and T≤T max is the total number of said plurality of time slots (116).

3. The wireless communication system (100) according to claim 1 or 2, wherein, The STDC(112) matrix B is defined based on δ ≤ D complex values {β 1 , β 2 , …, β δ}, where the entry of row i of the matrix B belongs to {±β 1 , ±β 2 , …, ±β δ , 0} or where is the complex conjugate of , and T max satisfies T max ≥ D.

4. The wireless communication system (100) according to any one of claims 1 to 3, wherein, The code of each DCS among the at least one DCS(106)d (d ∈ {1, 2, …, D}) is determined by the corresponding d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is denoted as B d .

5. The wireless communication system (100) according to any one of claims 1 to 4, wherein, For time slot (116)t i ∈{t 1 ,t 2 ,…,t T}, the controller (110) is configured to determine the encoded configuration for each DCS of the at least one DCS (106)d (d ∈ {1, 2, …, D}) as B i,d F d (φ d ), where F d (φ d ) is the scattering pattern of the at least one DCS (106)d, φ d is the basic phase shift configuration matrix of the at least one DCS (106)d, and B i,d represents the entry in the i-th row of the corresponding code B d .

6. The wireless communication system (100) according to any one of claims 1 to 5, wherein, For each time slot (116) t i , t i ∈ {t 1 , t 2 , …, t T}, the at least one transmitter (102) is further configured to: transmitting an information symbol x in the encoded radio frequency signal; wherein the encoded radio frequency signal includes a transformation of the information symbol x based on the STDC matrix B, the transformation of the information symbol x including: If the entries in the corresponding \(i\)-th row of the STDC matrix \(B\) belong to \(\{\pm\beta 1 ,\pm\beta 2 ,\ldots,\pm\beta δ ,0\}\), then the information symbol \(x\) at the time slot \((116)t i ; or If the entry in the corresponding i-th row of the STDC matrix B belongs to then the information symbol x i at the time slot (116)t * , where x * is the complex conjugate of the information symbol x.

7. The wireless communication system (100) according to any one of claims 1 to 6, wherein, the at least one receiver (104) is configured to: estimate one or more propagation channels via the at least one DCS (106) and / or the one or more direct propagation channels.

8. The wireless communication system (100) according to any one of claims 1 to 7, wherein, For each time slot (116) t i , t i ∈ {t 1 , t 2 , …, t T}, the at least one receiver (104) is further configured to: determine the information symbol x transmitted by the at least one transmitter (102) based on the STDC (112), based on the received encoded radio frequency signal, based on the estimated one or more propagation channels via the at least one DCS (106) and / or the estimated one or more direct propagation channels.

9. The wireless communication system (100) according to claim 2 or 3, wherein, One of the controller (110), the at least one transmitter (102), the at least one receiver (104), or the at least one DCS (106) is further configured to: Determine the STDC matrix B; Signal to send the total number T of the plurality of time slots (116) and the STDC matrix B to the controller (110) and / or the at least one transmitter (102) and / or the at least one receiver (104) and / or the at least one DCS (106); and / or signal to send the corresponding d-th column of the STDC matrix B and the total number T of the plurality of time slots (116) to the at least one DCS (106)d.

10. The wireless communication system (100) according to claim 9, wherein, The STDC matrix B is determined offline, and the STDC matrix B and / or the d-th column of the STDC matrix B are signaled before the at least one transmitter (102) transmits the encoded radio frequency signal.

11. The wireless communication system (100) according to any one of claims 1 to 10, wherein the at least one transmitter (102) and the at least one DCS (106) are synchronized.

12. A wireless communication method (200), comprising: The controller (110) controls at least one transmitter (102) to generate an encoded radio frequency signal during a plurality of time slots (116) based on the space-time DCS code STDC (112); The controller (110) controls a set of scattering elements (108) of at least one DCS (106) during the plurality of time slots (116) based on the STDC (112), the at least one DCS (106) includes a scattering surface (107), the scattering surface includes the set of scattering elements (108), and each scattering element (108) has a controllable phase shift; The at least one transmitter (102) transmits the encoded radio frequency signal to the at least one receiver (104) during the plurality of time slots (116); The at least one receiver (104) obtains the encoded radio frequency signal transmitted by the at least one transmitter (102) by receiving during the plurality of time slots (116); wherein the encoded radio frequency signal transmitted by the at least one transmitter (102) during the plurality of time slots (116) propagates from the at least one transmitter (102) to the at least one receiver (104) through one or more propagation channels (114), and the one or more propagation channels (114) include one or more propagation channels via the at least one DCS (106) and / or one or more direct propagation channels; Wherein, the STDC (112) depends on the total number of the at least one DCS (106) and the maximum number T of the plurality of time slots (116) max .

13. A computer program product, comprising program code that, when implemented on a processor, is configured to execute the wireless communication method (200) according to claim 12.

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