WIRELESS COMMUNICATION SYSTEM AND METHOD

Abstract

The disclosure provides a wireless communication system, comprising at least one DCS with a surface that comprises scattering elements having a controllable phase shift, at least one transmitter configured to transmit a coded radiofrequency signal to at least one receiver during a plurality of time slots, and a controller. The controller controls the at least one transmitter, based on a space time DCS code (STDC) to generate the coded radiofrequency signal during the plurality of time slots. The controller further controls, based on the STDC, the set of scattering elements of the at least one DCS during the plurality of time slots. The STDC depends on a total number of the at least one DCS and a maximum number of the plurality of time slots T.sub.max.

Claims

1. A wireless communication system comprising: at least one transmitter, configured to transmit a coded radiofrequency 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 that comprises a set of scattering elements, each scattering element having a controllable phase shift; a controller, configured to: control, based on a space time DCS code, STDC, the at least one transmitter to generate the coded radiofrequency signal during the plurality of time slots; control, based on the STDC, the set of scattering elements of the at least one DCS during the plurality of time slots; and at least one receiver, configured to obtain by reception, during the plurality of time slots, the coded radiofrequency signal transmitted by the at least one transmitter; wherein the coded radiofrequency 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; and wherein the STDC depends on a total number of the at least one DCS and a maximum number of the plurality of time slots T.sub.max.

2. The wireless communication system according to claim 1, wherein the STDC comprises a STDC matrix B, the STDC matrix B having a dimension TD, wherein D is a total number of the at least one DCS, with D1, and TT.sub.max is a total number of the plurality of time slots.

3. The wireless communication system according to claim 1, wherein the STDC matrix B is defined based on D complex values {.sub.1, .sub.2, . . . , .sub.}, wherein entries of a row i of the matrix B belong either to {.sub.1, .sub.2, . . . , .sub., 0} or to {*.sub.1, *.sub.2, . . . , *.sub., 0}, wherein is the complex conjugate of for {1, . . . , D} and T.sub.max satisfies T.sub.maxD.

4. The wireless communication system according to claim 1, wherein a code for each of the at least one DCS d, with d{1,2, . . . , D}, is determined by a respective d-th column of the STDC matrix B, the d-th column of the STDC matrix B being denoted as B.sub.d.

5. The wireless communication system according to claim 1, wherein, for a time slot t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the controller is configured to determine a coded configuration for each of the at least one DCS d, with d{1,2, . . . , D}, as B.sub.i,d F.sub.d (.sub.d), wherein F.sub.d(.sub.d) is a scattering pattern of the at least one DCS d, .sub.d is a base phase shift configuration matrix of the at least one DCS d, and B.sub.i,d denotes an entry in an i-th row of the respective code B.sub.d.

6. The wireless communication system according to claim 1, wherein, for each time slot t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the at least one transmitter is further configured to: transmit an information symbol x in the coded radiofrequency signal; wherein the coded radiofrequency signal comprises a transformation of the information symbol x based on the STDC matrix B, the transformation of the information symbol x comprising: the information symbol x at the time slot t.sub.i if entries of a respective i-th row of the STDC matrix B belong to {.sub.1, .sub.2, . . . , .sub., 0}; or an information symbol x* at the time slot t.sub.i if entries of the respective i-th row of the STDC matrix B belong to {*.sub.1, *.sub.2, . . . , *.sub., 0}, wherein x+is the complex conjugate of the information symbol x.

7. The wireless communication system according to claim 1, wherein the at least one receiver is configured to: estimate the one or more propagation channels via the at least one DCS and/or the one or more direct propagation channels.

8. The wireless communication system according to claim 1, wherein for each time slot t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the at least one receiver is further configured to: determine the information symbol x transmitted by the at least one transmitter based on the STDC, based on the received coded radiofrequency signal, and based on the estimated one or more propagation channels via the at least one DCS and/or the estimated one or more direct propagation channels.

9. The wireless communication system according to claim 2, wherein one of the controller, the at least one transmitter, the at least one receiver or the at least one DCS is further configured to: determine the STDC matrix B; and send the total number T of the plurality of time slots and the STDC matrix B by signaling to the controller and/or the at least one transmitter and/or the at least one receiver and/or the at least one DCS; and/or send by signaling to the at least one DCS d the respective d-th column of the STDC matrix B and the total number T of the plurality of time slots.

10. The wireless communication system 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, is sent by signaling before the at least one transmitter transmits the coded radiofrequency signal.

11. The wireless communication system according to claim 1, wherein the at least one transmitter and the at least one DCS are synchronized.

12. A wireless communication method comprising: controlling, by a controller, based on a space time DCS code, STDC, at least one transmitter to generate a coded radiofrequency signal during a plurality of time slots; controlling, by the controller, based on the STDC, a set of scattering elements of at least one DCS during the plurality of time slots, the at least one DCS comprising a scattering surface that comprises the set of scattering elements, each scattering element having a controllable phase shift; transmitting, by the at least one transmitter, the coded radiofrequency signal to at least one receiver during the plurality of time slots; and obtaining by reception, by the at least one receiver during the plurality of time slots, the coded radiofrequency signal transmitted by the at least one transmitter; wherein the coded radiofrequency 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; and wherein the STDC depends on a total number of the at least one DCS and a maximum number of the plurality of time slots T.sub.max.

13. The wireless communication method according to claim 12, wherein the STDC comprises a STDC matrix B, the STDC matrix B having a dimension TD, wherein D is a total number of the at least one DCS, with D1, and TT.sub.max is a total number of the plurality of time slots.

14. The wireless communication method according to claim 12, wherein the STDC matrix B is defined based on D complex values {.sub.1, .sub.2, . . . , .sub.}, wherein entries of a row i of the matrix B belong either to {.sub.1, .sub.2, . . . , .sub., 0} or to {*.sub.1, *.sub.2, . . . , *.sub., 0}, wherein is the complex conjugate of for {1, . . . , D} and T.sub.max satisfies T.sub.maxD.

15. The wireless communication method according to claim 12, wherein a code for each of the at least one DCS d, with d{1,2, . . . , D}, is determined by a respective d-th column of the STDC matrix B, the d-th column of the STDC matrix B being denoted as B.sub.d.

16. The wireless communication method according to claim 12, wherein, for a time slot t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the controller is configured to determine a coded configuration for each of the at least one DCS d, with d{1,2, . . . , D}, as B.sub.i,dF.sub.d(.sub.d), wherein F.sub.d(.sub.d) is a scattering pattern of the at least one DCS d, .sub.d is a base phase shift configuration matrix of the at least one DCS d, and B.sub.i,d denotes an entry in an i-th row of the respective code B.sub.d.

17. The wireless communication method according to claim 12, further comprises: for each time slot t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, transmit, by the at least one transmitter, an information symbol x in the coded radiofrequency signal; wherein the coded radiofrequency signal comprises a transformation of the information symbol x based on the STDC matrix B, the transformation of the information symbol x comprising: the information symbol x at the time slot t.sub.i if entries of a respective i-th row of the STDC matrix B belong to {.sub.1, .sub.2, . . . , .sub., 0}; or an information symbol x* at the time slot t.sub.i if entries of the respective i-th row of the STDC matrix B belong to {*.sub.1, *.sub.2, . . . , *.sub., 0}, wherein x* is the complex conjugate of the information symbol x.

18. The wireless communication method according to claim 12, further comprises: estimate, by the at least one receiver, the one or more propagation channels via the at least one DCS and/or the one or more direct propagation channels.

19. The wireless communication method according to claim 12, further comprises: for each time slot t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, determine, by the at least one receiver, the information symbol x transmitted by the at least one transmitter based on the STDC, based on the received coded radiofrequency signal, and based on the estimated one or more propagation channels via the at least one DCS and/or the estimated one or more direct propagation channels.

20. A non-transitory computer-readable storage medium comprising instructions which, when executed by a hardware of a wireless communication system, cause the wireless communication system to: controlling, by a controller, based on a space time DCS code, STDC, at least one transmitter to generate a coded radiofrequency signal during a plurality of time slots; controlling, by the controller, based on the STDC, a set of scattering elements of at least one DCS during the plurality of time slots, the at least one DCS comprising a scattering surface that comprises the set of scattering elements, each scattering element having a controllable phase shift; transmitting, by the at least one transmitter, the coded radiofrequency signal to at least one receiver during the plurality of time slots; and obtaining by reception, by the at least one receiver during the plurality of time slots, the coded radiofrequency signal transmitted by the at least one transmitter; wherein the coded radiofrequency 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; and wherein the STDC depends on a total number of the at least one DCS and a maximum number of the plurality of time slots T.sub.max.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The above described aspects and implementation forms will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

[0076] FIG. 1 shows an example of a DCS;

[0077] FIG. 2a)-b) show exemplary configurations of non-flat DCS scattering surfaces, and an exemplary configuration of a distributed DCS scattering surface;

[0078] FIG. 3 shows an exemplary signal that propagates from a transmitter to a receiver via a DCS through a propagation channel that 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;

[0079] FIG. 4 shows a schematic diagram of a wireless communication system according to this disclosure;

[0080] FIG. 5 shows an exemplary flowchart for generating a space time DCS code according to this disclosure;

[0081] FIG. 6 shows a schematic diagram of an example of a wireless communication system according to this disclosure;

[0082] FIG. 7 shows a schematic diagram of an example of a wireless communication system according to this disclosure

[0083] FIG. 8a)-b) show schematic diagrams of examples of a wireless communication system according to this disclosure.

[0084] FIG. 9 shows a schematic diagram of an example of a wireless communication system according to this disclosure;

[0085] FIG. 10 shows an example of exchanged information between the controller, one transmitter, two DCS and one receiver according to this disclosure;

[0086] FIG. 11 shows another example of exchanged information between the controller, one transmitter, two DCS and one receiver according to this disclosure;

[0087] FIG. 12 shows an example of exchanged information between the controller, one transmitter, D DCS and one receiver according to this disclosure;

[0088] FIGS. 13a)-b) show of examples of time slots in a wireless communication system according to this disclosure for the case of four information symbols transmitted.

[0089] FIG. 14 shows a wireless communications method according to this disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0090] FIG. 4 shows an exemplary embodiment of a wireless communication system 100 according to this disclosure. The wireless communication system 100 comprises at least one transmitter 102, configured to transmit a coded radiofrequency signal to at least one receiver 104 during a plurality of time slots 116. The system 100 further comprises at least one DCS 106 with a scattering surface 107. The scattering surface 107 comprises a plurality of scattering elements 106, each scattering element 106 has a controllable phase shift. The system 100 further comprises a controller 110, and at least one receiver 104 configured to obtain by reception, during the plurality of time slots 116, the coded radiofrequency signal transmitted by the at least one transmitter 102.

[0091] The controller 110 is configured to control, based on a space time DCS code 112, STDC, the at least one transmitter 102 to generate the coded radiofrequency signal during the plurality of time slots 116.

[0092] Further, the controller 110 is configured to control, based on the STDC 112, the set of scattering elements 108 of the at least one DCS 106 during the plurality of time slots 116. Thereby, the scattering elements 108 of the scattering surface 107 of the DCS 106 scatter the coded signal transmitted by the at least one transmitter 102 in a controlled manner that is based on the code STDC 112. Notably, since the STDC 112 does not depend on the number of scattering elements 108 of each of the at least one DCS, efficiency and low overhead is obtained.

[0093] The STDC 112 depends on a total number of the at least one DCS 106 and a maximum number of the plurality of time slots 116, denoted as T.sub.max.

[0094] The coded radiofrequency 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 comprise one or more propagation channels via the at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 comprise one or more direct propagation channels. That is, the one or more propagation channels 114 comprise one or more propagation channels between the at least one transmitter 102 and the at least one receiver 104 via the at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 comprise one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver. The one or more propagation channels 114 may not comprise direct propagation channels between the at least one transmitter 102 and the at least one receiver, for example in case that the direct propagation channels between the at least one transmitter 102 and the at least one receiver are blocked.

[0095] The STDC 112 comprises a STDC matrix B. The STDC matrix B has a dimension TD, where D is a total number of the at least one DCS 106, so that D1, and TT.sub.max is a total number of the plurality of time slots 116, and the maximum number of the plurality of time slots 116 is smaller than or equal to the total number of DCSs 106, T.sub.maxD.

[0096] The STDC matrix B is defined based on complex values {.sub.1, .sub.2, . . . , .sub.}, and a number of said complex values is smaller or equal than the total number of DCSs 106, i.e., D. Entries of a row i of the STDC matrix B belong either to {.sub.1, .sub.2, . . . , .sub., 0} or to {*.sub.1, *.sub.2, . . . , *.sub., 0}, where is the complex conjugate of for {1, . . . , D}.

[0097] The STDC matrix B can be derived from conventional STBC matrices. An exemplary flowchart for generating the STDC matrix B according to this disclosure is depicted in FIG. 5.

[0098] In step S502, the flowchart may take as inputs the total number of DCSs D and the maximum number of time slots 106 T.sub.maxD that are available or allowed for STDC.

[0099] Then, in step S504, a STBC matrix B that maps D complex values {.sub.1, .sub.2, . . . , .sub.} onto a TD matrix B may be chosen, such that TT.sub.max. The matrix B may be chosen such that the entries of any row i of B belong either to {.sub.1, .sub.2, . . . , .sub., 0} or to {*.sub.1, *.sub.2, . . . , *.sub., 0} but not both, where is the complex conjugate of for {1, . . . , D}. This constraint is related to the fact that the effect of a common scattering phase shift for all the scattering elements 108 of the DCS 106 affects the entire signal scattered by it with an overall phase shift, as explained later in the disclosure.

[0100] In step S506, the STDC matrix B may be determined by assigning to it the matrix chosen in step S504. The exemplary flowchart of FIG. 5 may provide the STDC matrix B as an output.

[0101] Referring to FIG. 4, a code for each of the at least one DCS d 106, with d{1,2, . . . , D}, is determined by a respective d-th column of the STDC matrix B. The d-th column of the STDC matrix B, which is denoted as B.sub.d, can also be referred to as a coding vector for the DCS d 106.

[0102] That is, for a total number of D DCSs 106, the code of the d-th DCS 106 (hereinafter in this disclosure it may be referred to as DCS d), with d{1,2, . . . , D}, is specified by the d-th column of the STDC matrix B. Thereby, a given DCS d 106 only requires knowledge of the corresponding column d of B.

[0103] Then, for each of the plurality of time slots 116, t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the controller 110 is configured to determine a coded configuration for each of the at least one DCS 106 d, with d{1,2, . . . , D}, as B.sub.i,d F.sub.d (.sub.d), where F.sub.d (.sub.d) is a scattering pattern of the at least one DCS d 106, .sub.d is a base phase shift configuration matrix of the at least one DCS d 106, and B.sub.i,d denotes an entry in an i-th row of the respective code B.sub.d, i.e., B.sub.i,d is the entry in in the i-th row and the d-th column of the STDC matrix B.

[0104] On controlling, based on the STDC 112, the set of scattering elements 108 of the at least one DCS 106 during the plurality of time slots 116, the controller 110 may control the at least one DCS 106 d to chose the d-th column of the STDC matrix B and to further determine the coded configuration mentioned above. Additionally or alternatively, the controller 110 may control the at least one DCS 106 during the plurality of time slots 116 in order to apply the determined coded configuration.

[0105] The base phase shift configuration matrix of the at least one DCS d 106 .sub.d can be determined locally at the corresponding DCS d 106. As such, each DCS d 106 can determine .sub.d independently and in a non-coordinated manner without signaling requirements. Alternatively, the controller may be configured to determine .sub.d for each of the DCS d 106 and may send each .sub.d to each DCS d 106 by signaling.

[0106] The coded configuration for each of the at least one DCS 106 d during a time slot t.sub.i takes the form B.sub.i,d F.sub.d (.sub.d)=.sub.d F.sub.d (.sub.d), i.e., the coded configuration for each of the at least one DCS 106 d is a scaled version of the scattering pattern F.sub.d (.sub.d), where the scaling is given by .sub.d. When the entries of the STDC matrix B are all of unit magnitude then the coverage of the at least one DCS d 106 when using a.sub.d F.sub.d (.sub.d) is the same as when using F.sub.d (.sub.d) since the complex scalar a.sub.d scaling the scattering pattern F.sub.d (.sub.d) is of unit magnitude thus scaling by .sub.d corresponds to applying a phase shift to the scattering pattern F.sub.d (.sub.d). Rotating the scattering pattern F.sub.d (.sub.d) by a phase shift does not change the scattering pattern in terms of energy perceived at each point in space, that is, the magnitude of the scattering pattern of the at least one DCSs 106 is not changed. This is beneficial since the one or more propagation channels via the at least DCS 106 remain fixed even when the coding is applied, and the only change is their overall phases (shifted by <(.sub.d)). As a result, by using the STDC 112 according to this disclosure, at least one propagation path via the at least one DCS 106 remains fixed up to a phase shift during the plurality of time slots 116, which facilitates channel estimation and signal combining at the at least one receiver 104.

[0107] The base phase shift configuration matrix .sub.d for each of the at least one DCS 106 and hence F.sub.d (.sub.d), may be determined in a flexible manner since the coding can be applied on top of the scattering pattern as an overall scaling defined by .sub.d. In other words, the coding according to this disclosure applies on top of any given scattering pattern F.sub.d (.sub.d); hence, the STDC 112 provides more flexibility than conventional coding, where the code imposes a phase shift pattern .sub.d that is updated throughout the coding hence a varying scattering pattern F.sub.d (.sub.d) is imposed and, as a result, the scattering pattern varies throughout the coding time slots.

[0108] Using Equation (1), a propagation channel via the DCS d 106 from a transmitter antenna of the at least one transmitter 102, referred to as transmitter antenna n, to a receiver antenna of the at least one receiver 104, referred to as receiver antenna m, when using the scattering pattern .sub.d F.sub.d (.sub.d) can be written as shown in Equation (3):

[00004]$\begin{array}{cc}\begin{array}{c}{g}_{m,d,n}=h_{{\mathrm{DCS}}_d.fwdarw.{\mathrm{RX}}_m}^T\left({}_d{F}_d\left({}_d\right)\right)h_{{\mathrm{TX}}_n.fwdarw.{\mathrm{DCS}}_d}\\ ={}_d\left(h_{{\mathrm{DCS}}_d.fwdarw.{\mathrm{RX}}_m}^T{F}_d\left({}_d\right)h_{{\mathrm{TX}}_n.fwdarw.{\mathrm{DCS}}_d}\right)\\ ={}_d{h}_{m,d,n}\end{array}& \left(3\right)\end{array}$

[0109] Since the STDC 112 according to this disclosure may change only .sub.d, it can be noted from Equation (3) that the coding results in a scaling of the underlying or base channel h.sub.m,d,n, which itself remains fixed during the T time slots 116. FIG. 4 shows a propagation channel 114 from the at least one transmitter 102 to the at least one receiver 104 via the at least one DCS 106, given by g.sub.m,d,n in Equation (3), when the at least one DCS d 106 uses the scattering pattern .sub.d F.sub.d (.sub.d).

[0110] In the exemplary embodiment of FIG. 4, for each time slot 116 t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.T}, the transmitter antenna n of the at least one transmitter 102 is further configured to transmit an information symbol x in the coded radiofrequency signal, where the coded radiofrequency signal comprises a transformation of the information symbol x based on the STDC matrix B.

[0111] The transformation of the information symbol x may be denoted generally as f.sub.TX (x, B, t.sub.i) and comprises: the information symbol x at the time slot 116 t.sub.i if entries of a respective i-th row of the STDC matrix B belong to {.sub.1, .sub.2, . . . , .sub., 0}, or an information symbol x* at the time slot 116 t.sub.i if entries of the respective i-th row of the STDC matrix B belong to {*.sub.1, *.sub.2, . . . , *.sub., 0}, where x* is the complex conjugate of the information symbol x.

[0112] The information symbol x to be transmitted by the transmitter antenna n of the at least one transmitter 102 only needs to be known at the at least one transmitter 102 and does not need to be known by the at least one DCS 106, thus, the wireless communication system 100 may reduce the overhead requirement. This is in contrast to the prior art, where the information symbol needs to be known at the at least one DCS 106.

[0113] Each of the at least one transmitter 102 may comprise a single transmitter antenna. Alternatively, each of the at least one transmitter 102 may comprise multiple transmitter antennas, and each transmitter antenna may be configured to transmit, based on the STDC 112, a different information symbol during the T time slots. In other words, in case that the at least one transmitter 102 may comprise multiple transmitter antennas, transmission from each transmitter antenna may be performed independently at each transmitter antenna and, hence, each transmitter antenna may be configured to transmit an independent information symbol x by coding its corresponding information symbol x using the STDC 112, as disclosed above, over the T time slots 116.

[0114] In this manner, the STDC 112 according to this disclosure can be a code for multiple independent single antenna transmitters, or for multiple independent multi antenna transmitters, and can also apply for coding with only a single transmitter with multiple antennas or for coding with only a single transmitter with only a single antenna. The latter is a desirable feature in communication systems with low complexity devices, for example IoT devices that may not be able to implement STBC as it would require coding over at least two transmitter antennas. In other words, the STDC 112 may allow taking advantage of space time diversity by coding one or more propagation channels via one or more DCSs instead of coding a symbol over multiple transmitter antennas.

[0115] Further advantageously, in the exemplary embodiment of the wireless communication system 100 of FIG. 4, the transmitted symbol x can be taken from any variable amplitude constellation, for example QAM with any number of constellation points (e.g. 4-QAM, 8-QAM, 16-QAM), or can be taken from PSK constellations, even if the DCS elements provide only phase shift control. In contrast, in customary Alamouti designs with DCS the symbols must be constant amplitude, hence limited to PSK constellations (e.g. 4-PSK, 8-PSK, 16-PSK) that have a worse performance than QAM constellations, when the DCS elements only provide phase shift control.

[0116] Referring to FIG. 4, the at least one transmitter 102 and the at least one DCS 106 are synchronized. Synchronization between the at least one transmitter 102 and the at least one DCS 106 can be achieved, for example, by using GPS signals. GPS-based synchronization is used in 5G to in order to synchronize evolved Node B (eNBs).

[0117] In the exemplary embodiment of FIG. 4, the at least one receiver 104 is configured to estimate the one or more propagation channels between the at least one transmitter and the at least one receiver 104 via the at least one DCS 106 and/or the one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver 104.

[0118] The one or more propagation channels g.sub.m,d,n via the at least one DCS d 106 with scattering pattern .sub.dF.sub.d(.sub.d) are given by Equation (3). The one or more direct propagation channels h.sub.0 may be propagation channels resulting from all paths from the at least one transmitter 102 to the at least one receiver 104 that do not propagate via the at least one DCS 106. As disclosed above the one or more propagation channels 114 may not comprise the one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver 104, for example in case where the direct propagation channels are blocked and, consequently, the one or more direct propagation channels may not be estimated by the at least one receiver 104.

[0119] Besides the plurality of time slots 116, additional time slots for training, or training time slots, may also be employed. The additional or training time slots may be used for transmission of training pilots p from the at least one transmitter 102 to the at least one receiver 104 for channel estimation in the at least one receiver 104.

[0120] Then, for each time slot 116 t.sub.i, with t.sub.i{t.sub.1, t.sub.2, . . . , t.sub.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 coded radiofrequency signal, and 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.

[0121] That is, upon estimation of the at least one propagation channels 114, the at least one receiver 104 can proceed to decode the received STDC coded signal transmitted by the transmitter antenna n of the at least one transmitter 110 in order to obtain an estimate of each information symbol x transmitted by the transmitter antenna n of the at least one transmitter 102 or by each transmitting antenna.

[0122] Each of the at least one receiver 104 may comprise a single receiver antenna. Alternatively, one or more of the at least one receiver 104 may comprise multiple receiver antennas, and each receiver antenna may be configured to obtain by reception, during the plurality of time slots 116, the coded radiofrequency signal transmitted by the at least one transmitter 102.

[0123] The estimation of the information symbol x by the at least one receiver 104 may be based on diversity combining using the coded radiofrequency signal received by the at least one receiver antenna of the at least one receiver 104 during the total number T of the plurality of time slots 116, the estimated one or more propagation channels via the at least one DCS 106 and/or the estimated direct propagation channels, and the STDC matrix B. The diversity combining can be based on known combining procedures that have been designed for STBC communications. In case of multiple receiver antennas, diversity combining can be applied separately to each coded radiofrequency signal received by each receiver antenna separately. Furthermore, if the multiple receiver antennas are collocated or share a signal processing unit, then the signals obtained from the multiple receiver antennas can be further combined for example in a Maximum Ratio Combining (MRC) way. Thereby, the STDC 112 according to this disclosure used in conjunction with diversity combining allows to use one or more direct propagation paths and/or one or more propagation paths via the at least one DCS 106 for simplified channel estimation and information symbol estimation at the at least one receiver 104.

[0124] In this exemplary embodiment, the controller 110 is configured to determine the STDC matrix B.

[0125] Since the coded radiofrequency signal generated by the at least one transmitter 102 is based on the STDC matrix B, this matrix may need to be known by the at least one transmitter 102. Also, the STDC matrix B may need to be known at the at least one receiver 104 to decode the received coded radiofrequency signal. Further, the STDC matrix B, additionally or alternatively B.sub.d, may need to be known by the at least one DCS 106. Thus, the controller is further configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the at least one transmitter 102, to the at least one receiver 104 and to the at least one DCS 106. This incurs in some overhead; however, since the STDC matrix B only has TD elements, the overhead is small.

[0126] Additionally or alternatively, since each of the at least one DCS 106 requires only its corresponding code, the controller may be configured to send by signaling to each of the at least one DCS d 106 the respective d-th column of the STDC matrix B, B.sub.d, instead of the full STDC matrix B, and the total number T of the plurality of time slots 116. Thereby, a further overhead reduction is achieved.

[0127] The controller 110 may be further configured to determine the STDC matrix B offline, and may be configured to send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the at least one transmitter 102, to the at least one receiver 104 and to the at least one DCS 106 before the at least one transmitter 102 transmits the coded radiofrequency signal to the at least one receiver 104 during the plurality of time slots 116.

[0128] In this manner, overhead may be further reduced and efficiency of the wireless communication system 100 may be enhanced.

[0129] Alternatively, the controller 110, the at least one transmitter 102, the at least one receiver 104, additionally or alternatively the at least one DCS 106 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the controller 110 may be configured to send by signaling to the at least one transmitter 102, to the at least one receiver 104 and to the at least one DCS 106, a code identifier. The code identifier may comprise information that specifies a STDC matrix B of the one or more STDC matrices B in a table to be used to generate the coded radiofrequency signal transmitted from the at least one transmitter 102 to the at least one receiver 104 during a plurality of time slots 116, to control the set of scattering elements 108 of the at least one DCS 106 during the plurality of time slots 116, and to decode the coded radiofrequency signal obtained by the at least one receiver 104 during the plurality of time slots 116. The indication information may be implemented, for example, by an index that may specify the STDC matrix B of the one or more STDC matrices B in the table to be used. Consequently, the overhead for communicating the STDC matrix B can be further reduced.

[0130] Alternatively, the at least one transmitter 102 may be configured to determine the STDC matrix B. Further, the at least one transmitter 102 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the controller 110, to the at least one receiver 104 and to the at least one DCS 106. Additionally or alternatively, the at least one transmitter 102 may be configured to send by signaling to each of the at least one DCS d 106 the respective d-th column of the STDC matrix B, instead of the full STDC matrix B, and the total number T of the plurality of time slots 116.

[0131] The at least one transmitter 102 may be further configured to determine the STDC matrix B offline. Then, the at least one transmitter 102 may be configured to send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the controller 110, to the at least one receiver 104 and to the at least one DCS 106 before the at least one transmitter 102 transmits the coded radiofrequency signal to the at least one receiver 104 during the plurality of time slots 116.

[0132] Each of the controller 110, the at least one transmitter 102, the at least one receiver 104, additionally or alternatively the at least one DCS 106 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the at least one transmitter 102 may be configured to send by signaling to the controller 110, to the at least one receiver 104 and to the at least one DCS 106, a code identifier. The code identifier may comprise information that specifies a STDC matrix B of the one or more STDC matrices B in a table to be used. The indication information may be implemented, for example, by an index that may specify the STDC matrix B of the one or more STDC matrices B in the table to be used.

[0133] Alternatively, the at least one DCS 106 may be configured to determine the STDC matrix B. The at least one DCS 106 may be further configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the controller 110, to the at least one transmitter 102, to the at least one receiver 104, additionally or alternatively to other DCSs d 106 of the at least one DCS 106. Additionally or alternatively, the at least one DCS 106 may be configured to send by signaling to other DCSs d 106 of the at least one DCS 106 the respective d-th column of the STDC matrix B, instead of the full STDC matrix B, and the total number T of the plurality of time slots 116.

[0134] Further, the at least one DCS 106 may be configured to determine the STDC matrix B offline. Then, the at least one DCS 106 may be configured to send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the controller 110, to the at least one transmitter 102, to the at least one receiver 104, and to other DCSs 106 of the at least one DCS 106 before the at least one transmitter 102 transmits the coded radiofrequency signal to the at least one receiver 104 during the plurality of time slots 116.

[0135] Each of the controller 110, the at least one transmitter 102, the at least one receiver 104, additionally or alternatively the at least one DCS 106 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the at least one DCS 106 may be configured to send by signaling to the controller 110, the at least one transmitter 102, to the at least one receiver 104 and to other DCSs 106 of the at least one DCS 106, a code identifier. The code identifier may comprise information that specifies a STDC matrix B of the one or more STDC matrices B in a table to be used. The indication information may be implemented, for example, by an index that may specify the STDC matrix B of the one or more STDC matrices B in the table to be used.

[0136] Alternatively, the at least one receiver 104 may be configured to determine the STDC matrix B. Further, the at least one receiver 104 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the controller 110, to the at least one transmitter 102 and to the at least one DCS 106. Additionally or alternatively, the at least one receiver 104 may be configured to send by signaling to the at least one DCS d 106 the respective d-th column of the STDC matrix B, instead of the full STDC matrix B, and the total number T of the plurality of time slots 116.

[0137] The at least one receiver 104 may be configured to determine the STDC matrix B offline. Then, the at least one receiver 104 may be configured to send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the controller 110, to the at least one transmitter 102 and to the at least one DCS 106 before the at least one transmitter 102 transmits the coded radiofrequency signal to the at least one receiver 104 during the plurality of time slots 116.

[0138] Each of the controller 110, the at least one transmitter 102, the at least one receiver 104 and/or the at least one DCS 106 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the at least one receiver 104 may be configured to send by signaling to the controller 110, to the at least one transmitter 102 and to the at least one DCS 106, a code identifier. The code identifier may comprise information that specifies a STDC matrix B of the one or more STDC matrices B in a table to be used. The indication information may be implemented, for example, by an index that may specify the STDC matrix B of the one or more STDC matrices B in the table to be used.

[0139] The STDC 112 according to this disclosure may be applied, for example, for scaling a DCS scattering pattern by a complex scalar. A conventional model of the scattering pattern F.sub.d (.sub.d) for a DCS d of the at least one DCS 106 with S.sub.d scattering elements 108 is given such as provided in Equation (4):

[00005]$\begin{array}{cc}{F}_d\left({}_d\right)=\mathrm{diag}\left({}_{d,1}{e}^{j{}_{d,1}},{}_{d,2}{e}^{j{}_{d,2}},.Math.,{}_{d,}{e}^{j{}_{d,}},.Math.,{}_{d,S_d}{e}^{j{}_{d,S_d}}\right),& \left(4\right)\end{array}$

where the base phase shift configuration matrix of the DCS d is .sub.d=[.sub.d,1, .sub.d,2, . . . , .sub.d,, . . . , .sub.d,S.sub.d], .sub.d, is the scattering phase of the scattering element 108 of the DCS d 106, and .sub.d, represents a scattering amplitude due to the scattering element .sub.d 108, which is related, for example, to the radar cross section of the scattering element 108.

[0140] Given a complex scalar

[00006]${}_d={}_d{e}^{j{}_d},$

scaling the scattering pattern F.sub.d (.sub.d) of a DCS d 106 by aa is obtained by applying a new phase matrix .sub.d.sup.new to the scattering elements 108 of the at least one DCS d 106 as shown in Equation (5) and a new scaling of the scattering amplitude to the scattering elements 108 of the DCS d given in Equation (6):

[00007]$\begin{array}{cc}\begin{array}{c}{}_d^{\mathrm{new}}=\left[{}_{d,1}^{\mathrm{new}},{}_{d,2}^{\mathrm{new}},.Math.,{}_{d,}^{\mathrm{new}},.Math.,{}_{d,S_d}^{\mathrm{new}}\right]\\ =\left[{}_{d,1}+{}_d,{}_{d,2}+{}_d,.Math.,{}_{d,}+{}_d,.Math.,{}_{d,S_d}+{}_d\right]\\ ={}_d-{}_d\end{array}& \left(5\right)\end{array}$$\mathrm{and}$$\begin{array}{cc}{}_{d,1}^{\mathrm{new}}={}_d{}_{d,1},{}_{d,2}^{\mathrm{new}}={}_d{}_{d,2},.Math.,{}_{d,}^{\mathrm{new}}={}_d{}_{d,},.Math.,{}_{d,S_d}^{\mathrm{new}}={}_d{}_{d,S_d}& \left(6\right)\end{array}$

[0141] Applying the phase in Equation (5) and the amplitude scaling in Equation (6) to the DCS elements results in a new scattering pattern given in Equation (7):

[00008]$\begin{array}{cc}\begin{array}{c}{F}_d^{\mathrm{new}}\left({}_d^{\mathrm{new}}\right)=\mathrm{diag}\left({}_{d,1}^{\mathrm{new}}{e}^{j{}_{d,1}^{\mathrm{new}}},{}_{d,2}^{\mathrm{new}}{e}^{j{}_{d,2}^{\mathrm{new}}},.Math.,{}_{d,}^{\mathrm{new}}{e}^{j{}_{d,}^{\mathrm{new}}},.Math.,{}_{d,S_d}^{\mathrm{new}}{e}^{j{}_{d,S_d}^{\mathrm{new}}}\right)\\ =\mathrm{diag}\left({}_d{}_{d,1}{e}^{j\left({}_{d,1}+{}_d\right)},{}_d{}_{d,2}{e}^{j\left({}_{d,2}+{}_d\right)},.Math.,{}_d{}_{d,}{e}^{j\left({}_{d,}+{}_d\right)},.Math.,{}_d{}_{d,S_d}{e}^{j\left({}_{d,S_d}+{}_d\right)}\right)\\ ={}_d{e}^{j{}_d}\mathrm{diag}\left({}_{d,1}{e}^{j{}_{d,1}},{}_{d,2}{e}^{j{}_{d,2}},.Math.,{}_{d,}{e}^{j{}_{d,}},.Math.,{}_{d,S_d}{e}^{j{}_{d,S_d}}\right)\\ ={}_d{e}^{j{}_d}{F}_d\left({}_d\right)\\ ={}_d{F}_d\left({}_d\right)\end{array}& \left(7\right)\end{array}$

[0142] As can be observed from Equation (7) above, the new scattering pattern is the scattering pattern F.sub.d (.sub.d) scaled by .sub.d, as disclosed above.

[0143] In another example, the STDC 112 may be applied for scaling a DCS scattering pattern by the conjugate of a complex scalar. Given a complex scalar

[00009]${}_d={}_d{e}^{j{}_d},$

scaling a scattering pattern F.sub.d (.sub.d) of a DCS d 106 by *.sub.d is obtained in a similar manner as Equation (5) and Equation (6) above, but instead of adding a phase .sub.d to the base phase shift configuration matrix .sub.d, a phase .sub.d is added as shown in Equation (8):

[00010]$\begin{array}{cc}\begin{array}{c}{}_d^{\mathrm{new}}=\left[{}_{d,1}^{\mathrm{new}},{}_{d,2}^{\mathrm{new}},.Math.,{}_{d,}^{\mathrm{new}},.Math.,{}_{d,S_d}^{\mathrm{new}}\right]\\ =\left[{}_{d,1}-{}_d,{}_{d,2}-{}_d,.Math.,{}_{d,}-{}_d,.Math.,{}_{d,S_d}-{}_d\right]\\ ={}_d-{}_d\end{array}& \left(8\right)\end{array}$

[0144] With the new phases as described in Equation (8) and the new scaling as defined above in Equation (6), the new scattering pattern obtained is given in Equation (9):

[00011]$\begin{array}{c}{F}_d^{\mathrm{new}}\left({}_d^{\mathrm{new}}\right)=\mathrm{diag}\left({}_{d,1}^{\mathrm{new}}{e}^{j{}_{d,1}^{\mathrm{new}}},{}_{d,2}^{\mathrm{new}}{e}^{j{}_{d,2}^{\mathrm{new}}},.Math.,{}_{d,}^{\mathrm{new}}{e}^{j{}_{d,}^{\mathrm{new}}},.Math.,{}_{d,S_d}^{\mathrm{new}}{e}^{j{}_{d,S_d}^{\mathrm{new}}}\right)\\ =\mathrm{diag}\left({}_d{}_{d,1}{e}^{j\left({}_{d,1}-{}_d\right)},{}_d{}_{d,2}{e}^{j\left({}_{d,2}-{}_d\right)},.Math.,{}_d{}_{d,}{e}^{j\left({}_{d,}+-{}_d\right)},.Math.,{}_d{}_{d,S_d}{e}^{j\left({}_{d,S_d}-{}_d\right)}\right)\\ ={}_d{e}^{-j{}_d}\mathrm{diag}\left({}_{d,1}{e}^{j{}_{d,1}},{}_{d,2}{e}^{j{}_{d,2}},.Math.,{}_{d,}{e}^{j{}_{d,}},.Math.,{}_{d,S_d}{e}^{j{}_{d,S_d}}\right)\\ ={}_d{e}^{-j{}_d}{F}_d\left({}_d\right)\\ ={}_d^{*}{F}_d\left({}_d\right),\end{array}$

which is the scattering pattern F.sub.d (.sub.d) scaled by the conjugate of .sub.d.

[0145] In a further example, the STDC 112 may be applied for scaling a DCS scattering pattern by the negative conjugate of a complex scalar. Given a complex scalar

[00012]${}_d={}_d{e}^{j{}_d},$

scaling a scattering pattern F.sub.d (.sub.d) of a DCS d 106 by *.sub.d is obtained in a similar manner as in Equation (5) and Equation (6) above but instead of adding a phase .sub.d to the base phase shift configuration matrix .sub.d, a phase .sub.d+ is added, as shown in Equation (10):

[00013]$\begin{array}{cc}\begin{array}{c}{}_d^{\mathrm{new}}=\left[{}_{d,1}^{\mathrm{new}},{}_{d,2}^{\mathrm{new}},.Math.,{}_{d,}^{\mathrm{new}},.Math.,{}_{d,S_d}^{\mathrm{new}}\right]\\ =\left[{}_{d,1}-{}_d+,{}_{d,2}-{}_d+,.Math.,{}_{d,}-{}_d+,.Math.,{}_{d,S_d}-{}_d+\right]\\ ={}_d-{}_d+.\end{array}& \left(10\right)\end{array}$

[0146] With the new phases as described in Equation (10) above and the new scaling as defined in Equation (6), the new obtained scattering pattern is given by Equation (11):

[00014]$\begin{array}{c}{F}_d^{\mathrm{new}}\left({}_d^{\mathrm{new}}\right)=\mathrm{diag}\left({}_{d,1}^{\mathrm{new}}{e}^{j{}_{d,1}^{\mathrm{new}}},{}_{d,2}^{\mathrm{new}}{e}^{j{}_{d,2}^{\mathrm{new}}},.Math.,{}_{d,}^{\mathrm{new}}{e}^{j{}_{d,}^{\mathrm{new}}},.Math.,{}_{d,S_d}^{\mathrm{new}}{e}^{j{}_{d,S_d}^{\mathrm{new}}}\right)\\ =\mathrm{diag}\left({}_d{}_{d,1}{e}^{j\left({}_{d,1}-{}_d+\right)},{}_d{}_{d,2}{e}^{j\left({}_{d,2}-{}_d+\right)},.Math.,{}_d{}_{d,}{e}^{j\left({}_{d,}-{}_d+\right)},.Math.,{}_d{}_{d,S_d}{e}^{j\left({}_{d,S_d}-{}_d+\right)}\right)\\ ={}_d{e}^{-j{}_d+j}\mathrm{diag}\left({}_{d,1}{e}^{j{}_{d,1}},{}_{d,2}{e}^{j{}_{d,2}},.Math.,{}_{d,}{e}^{j{}_{d,}},.Math.,{}_{d,S_d}{e}^{j{}_{d,S_d}}\right)\\ ={}_d{e}^{-j{}_d+j}{F}_d\left({}_d\right)\\ ={}_d{e}^{-j{}_d}{F}_d\left({}_d\right)\\ =-{}_d^{*}{F}_d\left({}_d\right)\end{array}$

that is the scattering pattern of the at least one DCS d 106, F.sub.d (.sub.d), scaled by the negative conjugate of .sub.d.

[0147] The above examples for a DCS pattern scaling consider scaling by a complex scalar and, hence, modify the scattering amplitude and phase of the scattering unit elements 108 of the at least one DCS 106. However, having the scattering elements 108 of the at least one DCS 106 with controllable scattering amplitude is challenging, and therefore most of the known DCS configurations are for DCSs that only provide scattering phase control. In cases where only the scattering phase of the scattering elements 108 of the at least one DCS 106 can be controlled, a procedure as described in the examples above applies by simply setting .sub.d=1.

[0148] FIG. 6 shows a schematic diagram of an example of a wireless communication system 100, which builds on the exemplary embodiment of shown in FIG. 4. Same elements are labelled with the same reference signs. In this example, the wireless communication system 100 may comprise the controller 110, one transmitter 102 with one transmitter antenna, one receiver with one receiver antenna 104 and two DCSs 106-1, 106-2. Each DCS 106-1, 106-2 may comprise a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may comprise a set of scattering elements 108-1, 108-2.

[0149] The controller 110 may be configured to determine the STDC 112, that is, the controller 110 may be configured to determine the STDC matrix B. In this example, the total number of DCS is D=2 and it may be considered that T.sub.max=2 and =2, which meets the requirement of D. A well-known STBC matrix that maps two complex values {.sub.1, .sub.=2} onto a TD matrix B such that TT.sub.max is the 22 Alamouti STBC matrix, given in Equation (12):

[00015]$\begin{array}{cc}B=\left[\begin{array}{cc}{}_1& {}_2\\ -{}_2^{*}& {}_1^{*}\end{array}\right].& \left(12\right)\end{array}$

[0150] This matrix B meets the constraint that the entries of a given row belong either to {.sub.1, .sub.2, 0} or to {*.sub.1, *.sub.2, 0} but not to both. This is easily verifiable by inspection, since the entries of row 1 of the matrix B given in Equation (12) are {.sub.1, .sub.2}{.sub.1, .sub.2, 0} and the entries of row 2 of matrix B are {*.sub.1, *.sub.2}{*.sub.1, *.sub.2, 0}. In this example, .sub.1 and .sub.2 are generally expressed as scalar complex values, and specific values for .sub.1 and .sub.2 are not assigned.

[0151] Then, the controller 110 may be configured to choose the Alamouti matrix B of Equation (12) as the STDC matrix B.

[0152] Further, the controller 110 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the transmitter 102, to the receiver 104 and to the DCSs 106-1, 106-2. Alternatively, instead of the full STDC matrix B, the controller 110 may send by signaling to each of the DCSs 106-1, 106-2 the respective d-th column of the STDC matrix B.

[0153] The controller 110 may be configured to determine the STDC matrix B offline, and may send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the transmitter 102, to the receiver 104 and to the DCSs 106-1, 106-2 before the transmitter 102 transmits the coded radiofrequency signal to the receiver 104 during the plurality of time slots 116.

[0154] Alternatively, the controller 110, the transmitter 102, the receiver 104, additionally or alternatively the DCSs 106-1, 106-2 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the controller 110 may be configured to send by signaling to the transmitter 102, to the receiver 104 and to the DCSs 106-1, 106-2, a code identifier. The code identifier may comprise information that specifies a STDC matrix B of the one or more STDC matrices B in a table to be used. The indication information may be implemented, for example, by an index that may specify the STDC matrix B of the one or more STDC matrices B in the table to be used.

[0155] The controller 110 may be further configured to determine the base phase shift configuration matrices .sub.1, .sub.2 for each DCS 106-1, 106-2 respectively. The base phase shift configuration matrices .sub.1, .sub.2 may be obtained by the controller 110 via any arbitrary, or random fashion or from a predefined list or using any available previous knowledge about the DCSs 106-1, 106-2.

[0156] Then, the controller 110 may control, based on the STDC 112, the set of scattering elements 108-1, 108-2 of the DCS 106-1, 106-2 during the T=2 time slots 116. That is, for each time slot 116 t.sub.i{t.sub.1, t.sub.2} of the T=2 time slots, the controller 110 may be configured to determine the coded configuration for the DCS d, with d=1, 2, by setting a scattering pattern equal to B.sub.i,d F.sub.d (.sub.d)=.sub.d F.sub.d (.sub.d), with .sub.d=B.sub.i,d, where B.sub.i,d is the entry in the i-th row and d-th column of matrix B as disclosed above, and F.sub.d (.sub.d) is the scattering pattern of each DCS d 106-1, 106-2.

[0157] Alternatively, the controller 110 may control each DCS 106-1, 106-2 to choose the respective code B.sub.d and to determine the respective coded configuration.

[0158] For the STDC matrix B defined in Equation (12), for the time slot t.sub.1, the code for the DCS d=1 106-1 is determined by the first entry of the respective code B.sub.1, i.e., the entry in the first row and the first column of the STDC matrix B provided in Equation (12) sets .sub.1=.sub.1; thus, the controller 110 may be configured to determine the coded configuration for the DCS d=1 106-1, as B.sub.1,1 F.sub.1 (.sub.1), which is equal to .sub.1 F.sub.1 (.sub.1). At time slot t.sub.1, the code for the DCS d=2 106-2 is determined by the first entry of the respective code B.sub.2, and the controller 110 may determine the coded configuration for the DCS d=2 106-2 as B.sub.1,2 F.sub.2 (.sub.2) that is equal to B.sub.2 F.sub.2 (.sub.2), where .sub.2 is the first entry of the respective code B.sub.2, i.e., the entry in the first row and the second column of the STDC matrix B in Equation (12) sets .sub.2=.sub.2.

[0159] Further, for the time slot t.sub.2, the code for the DCS d=1 106-1 is determined by the second entry of B.sub.1, the entry in the second row and the first column of the STDC matrix B in Equation (12) sets .sub.1=*.sub.2; thus the coded configuration or scattering pattern is B.sub.2,1 F.sub.1 (.sub.1)=*.sub.2F.sub.1 (.sub.1). Similarly, for the time slot t.sub.2, the code for the DCS d=2 106-2 is determined by the second entry of B.sub.2, the entry in the second row and the second column of the STDC matrix B in Equation (12) sets .sub.2=*.sub.1, and the coded configuration or scattering pattern for the DCS d=2 106-2 is B.sub.2,2F.sub.2 (.sub.2)=*.sub.1F.sub.2(.sub.2). The resulting coded configuration for each time slot 116 and for each DCS 106-1, 106-2 is shown in Table 1.

TABLE-US-00001 TABLE 1 Scattering Pattern Scattering Pattern DCS 1 DCS 2 .sub.1F.sub.1(.sub.1) .sub.2F.sub.2(.sub.2) Time slot t.sub.1 .sub.1F.sub.1(.sub.1) .sub.2F.sub.2(.sub.2) Time slot t.sub.2 .sub.2*F.sub.1(.sub.1) .sub.1*F.sub.2(.sub.2)

[0160] In this example with a single transmitter 101 and a single receiver 104, each with a single antenna respectively hence n=1 and m=1, the one or more propagation channels via the two DCSs 106-1, 106-2 are denoted as h.sub.1=h.sub.1,1,1 and h.sub.2=h.sub.1,2,1, which are based on Equation (1), are defined as Equation (13) and Equation (14):

[00016]$\begin{array}{cc}{h}_1=h_{1,1,1}=h_{{\mathrm{DCS}}_1.fwdarw.{\mathrm{RX}}_1}^T{F}_1\left({}_1\right)h_{{\mathrm{TX}}_1.fwdarw.{\mathrm{DCS}}_1},& \left(13\right)\end{array}$$\begin{array}{cc}{h}_2=h_{1,2,1}=h_{{\mathrm{DCS}}_2.fwdarw.{\mathrm{RX}}_1}^T{F}_2\left({}_2\right)h_{{\mathrm{TX}}_1.fwdarw.{\mathrm{DCS}}_2}.& \left(14\right)\end{array}$

[0161] Using Equation (3), which defines that for a DCS d with scattering pattern equal to .sub.d F.sub.d (.sub.d), the resulting propagation channel via the DCS d from the at least one transmitter 102 n=1 to the at least one receiver 104 m=1 is g.sub.1,d,1=.sub.dh.sub.1,d,1. Further, for brevity of notation, it is defined g.sub.1=g.sub.1,1,1=.sub.1h.sub.1,1,1=.sub.1h.sub.1 and g.sub.2=9.sub.1,2,1=.sub.2h.sub.1,2,1=.sub.2h.sub.2. The expressions for the propagation channels via each DCS 106-1, 106-2 are shown in Table 2.

TABLE-US-00002 TABLE 2 Channel via Channel via DCS 1 DCS 2 g.sub.1 = .sub.1h.sub.1 g.sub.2 = .sub.2h.sub.2 Time slot t.sub.1 .sub.1h.sub.1 .sub.2h.sub.2 Time slot t.sub.2 .sub.2*h.sub.1 .sub.1*h.sub.2

[0162] As it can be seen from Table 2, the value of .sub.d changes as a function of the STDC 112 that is specified by the D complex values {.sub.1, .sub.2, . . . , .sub.} of the STDC matrix B and, thus, provides channel programming with STDC 112 having the controlled channel variations shown in Table 2.

[0163] Then, the controller 110 may be configured to control, based on the STDC 112, the transmitter 102 to generate the coded radiofrequency signal. That is, for each time slot 116 t.sub.i, the transmitter 102 may be configured to transmit an information symbol x in the coded radiofrequency signal. The coded radiofrequency signal may comprise the transformation of the information symbol x based on the STDC matrix B, f.sub.TX (x, B, t.sub.i). For the time slot t.sub.1, since the entries of the first row of matrix B given in Equation (12) are {.sub.1, .sub.2}{.sub.1, .sub.2, 0}, then the transmitter 102 may be configured to send the symbol x at time slot t.sub.1. For time slot t.sub.2, since the entries of the second row of matrix B are {*.sub.1, *.sub.2}{*.sub.1, *.sub.2, 0} then the transmitter 102 may be configured to send the symbol x*. The transmitted symbol for each time slot 116 is summarized in Table 3.

TABLE-US-00003 TABLE 3 Transmitted symbol Time slot t.sub.1 x Time slot t.sub.2 x*

[0164] In the example of FIG. 6, the transmitter 102 may be further configured, based on the STDC 112, to transmit training pilots p during additional or training time slots. Said training pilots p sent during the training time slots may be needed for the receiver 104 in order to estimate the one or more propagation channels 114, in case that the estimates of the one or more propagation channels via the at least one DCS and/or one or more direct propagation channels are not yet available at the receiver 104.

[0165] Table 4 shows the coded signal transmitted by the transmitter 102 including the extra time slots for transmission of training pilots p for channel estimation, and the time slots t.sub.1 and t.sub.2 116 for transmission of the coded signal transmitted by the transmitter 102 (or the transformation of the information symbol sent by the transmitter 102). The value of .sub.d for each DCS 106-1, 106-2 is also shown in Table 4. As explained above, during the two time slots 116 t.sub.1, t.sub.2, .sub.d depends on the STDC matrix B. During the additional time slots for training, the controller 110 may be configured to control the set of scattering elements 108-1, 108-2 of the DCSs 106-1 106-2 by setting values of .sub.d, for example, in a predetermined manner. The resulting direct propagation channels, denoted as h.sub.0 between the transmitter 102 and the receiver 104, the propagation channels via the two DCSs 106-1 106-2 h.sub.1 and h.sub.2, as well as the coded radiofrequency signal received by the receiver 104 are also included in Table 4.

TABLE-US-00004 TABLE 4 Channel Channel Transmitted Direct via DCS 1 via DCS 2 symbol .sub.1 .sub.2 channel g.sub.1 g.sub.2 Received signal Training p 1 1 h.sub.0 h.sub.1 h.sub.2 y.sub.p.sub.1 = time slot (h.sub.0 + h.sub.1 + h.sub.2)p Training p 1 1 h.sub.0 h.sub.1 h.sub.2 y.sub.p.sub.2 = time slot (h.sub.0 + h.sub.1 h.sub.2)p Training p 1 1 h.sub.0 h.sub.1 h.sub.2 y.sub.p.sub.3 = time slot (h.sub.0 h.sub.1 h.sub.2)p Time slot x .sub.1 .sub.2 h.sub.0 .sub.1h.sub.1 .sub.2h.sub.2 y.sub.t.sub.1 = t.sub.1 (h.sub.0 + .sub.1h.sub.1 + .sub.2h.sub.2)x Time slot x* .sub.2* .sub.1* h.sub.0 .sub.2*h.sub.1 .sub.1*h.sub.2 y.sub.t.sub.2 = t.sub.2 (h.sub.0 .sub.2*h.sub.1 + .sub.1*h.sub.2)x*

[0166] The transmitted pilots p may be known at the receiver 104. Then, for each training time slot the receiver 104 may be configured to estimate the one or more propagation channels via the DCS 106-1, 106-2, h.sub.1, h.sub.2, additionally or alternatively to estimate the one or more direct propagation channels h.sub.0 , based on the received training pilots p and on the received signals y.sub.p.sub.1, y.sub.p.sub.2 and y.sub.p.sub.3. These channels are just scalars, so their estimation is easier compared to estimating channels whose sizes depend on the number of scattering elements 108-1, 108-2 of each DCS 106-1 106-2, as it is the case in customary algorithms that use DCSs.

[0167] Further, the receiver 104 may be configured to determine the information symbol x transmitted by the transmitter 102 based on the STDC 112, based on the received coded radiofrequency signals during the time slots 116 and based on the estimated one or more propagation channels via the at least one DCS 106, additionally or alternatively the estimated one or more direct propagation channels.

[0168] To that end, the receiver 104 may proceed as follows. The received signal vector y is constructed by stacking the signal received at the first time slot, namely y.sub.t.sub.1 and using the conjugate of the signal received at the second time slot, namely

[00017]$y_{t_2}^{*}.$

The signal received in the second time slot is conjugated because the information symbol transmitted in the second time slot was sent as the conjugate x*. Following this approach, in the present disclosure the received signal vector y may be expressed as provided in Equation (15):

[00018]$\begin{array}{cc}y=\left[\begin{array}{c}{y}_{t_1}\\ y_{t_2}^{*}\end{array}\right]=\left[\begin{array}{ccc}{h}_1& h_2& h_0\\ h_2^{*}& -h_1^{*}& h_0^{*}\end{array}\right]\left[\begin{array}{c}{}_{1}x\\ {}_{2}x\\ x\end{array}\right].& \left(15\right)\end{array}$

[0169] Since the one or more propagation channels h.sub.0, h.sub.1 and h.sub.2 have been estimated by the receiver 104, an overall channel matrix H can be constructed as in Equation (16):

[00019]$\begin{array}{cc}H=\left[\begin{array}{ccc}{h}_1& h_2& h_0\\ h_2^{*}& -h_1^{*}& h_0^{*}\end{array}\right].& \left(16\right)\end{array}$

[0170] The channel matrix H can be used to write a received signal vector as in Equation (17):

[00020]$\begin{array}{cc}y=H\left[\begin{array}{c}{}_{1}x\\ {}_{2}x\\ x\end{array}\right].& \left(17\right)\end{array}$

[0171] Then, a combining matrix Q can be computed as in Equation (18):

[00021]$\begin{array}{cc}Q=H^{*}=\left[\begin{array}{cc}{h}_1^{*}& h_2\\ h_2^{*}& -h_1\\ h_0^{*}& h_0\end{array}\right]& \left(18\right)\end{array}$

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

[00022]$\begin{array}{cc}\begin{array}{c}\mathrm{Qy}=\left[\begin{array}{cc}{h}_1^{*}& h_2\\ h_2^{*}& -h_1\\ h_0^{*}& h_0\end{array}\right]\left[\begin{array}{ccc}{h}_1& h_2& h_0\\ h_2^{*}& -h_1^{*}& h_0^{*}\end{array}\right]\left[\begin{array}{c}{}_{1}x\\ {}_{2}x\\ x\end{array}\right]\\ =\left[\begin{array}{ccc}{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)& 0& h_1^{*}{h}_0+h_2{h}_0^{*}\\ 0& {}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)& h_2^{*}{h}_0-h_1{h}_0^{*}\\ {}_1\left(h_0^{*}{h}_1+h_0{h}_2^{*}\right)& {}_2\left(h_0^{*}{h}_2-h_0{h}_1^{*}\right)& 2{.Math.h_0.Math.}^2\end{array}\right]\left[\begin{array}{c}x\\ x\\ x\end{array}\right]\end{array}.& \left(19\right)\end{array}$

[0172] The diagonal terms in Equation (19) show that the received and combined signals using the combining matrix Q given in Equation (18) offer diversity combining of direct paths between the transmitter 102 and the receiver 104 and paths between the transmitter 102 and the receiver 104 via the DCSs 106-1, 106-2. The diagonal terms contribute to coherent combining contributions of the direct paths and the paths via the DCSs 106-1, 106-2.

[0173] Since the STDC matrix B and its complex values .sub.1 and .sub.2 may be known at the receiver 104, the receiver 104 can be configured to construct a normalizing matrix as in Equation (20):

[00023]$\begin{array}{cc}N=\mathrm{diag}\left(\frac{1}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)},\frac{1}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)},\frac{1}{2{.Math.h_0.Math.}^2}\right).& \left(20\right)\end{array}$

[0174] Using the received signal vector y, the combining matrix Q and the normalizing matrix N, the receiver 104 may obtain three initial estimates {circumflex over (x)}.sub.init,1, {circumflex over (x)}.sub.init,2, {circumflex over (x)}.sub.init,3 of the information symbol x transmitted by the transmitter 102 in the coded radiofrequency signal, given in Equation (21):

[00024]$\begin{array}{cc}\begin{array}{c}\left[\begin{array}{c}{\hat{x}}_{\mathrm{init},1}\\ {\hat{x}}_{\mathrm{init},2}\\ {\hat{x}}_{\mathrm{init},3}\end{array}\right]=\mathrm{NQy}\\ =N\left[\begin{array}{ccc}{.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2& 0& h_1^{*}{h}_0+h_2{h}_0^{*}\\ 0& {.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2& h_2^{*}{h}_0-h_1{h}_0^{*}\\ h_0^{*}{h}_1+h_0{h}_2^{*}& h_0^{*}{h}_2-h_0{h}_1^{*}& 2{.Math.h_0.Math.}^2\end{array}\right]\left[\begin{array}{c}{}_{1}x\\ {}_{2}x\\ x\end{array}\right]\\ =\left[\begin{array}{ccc}1& 0& \frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\\ 0& 1& \frac{g_2^{*}{h}_0-g_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\\ \frac{{}_1\left(h_0^{*}{h}_1+h_0{h}_2^{*}\right)}{2{.Math.h_0.Math.}^2}& \frac{{}_2\left(h_0^{*}{h}_2-h_0{h}_1^{*}\right)}{2{.Math.h_0.Math.}^2}& 1\end{array}\right]\left[\begin{array}{c}x\\ x\\ x\end{array}\right]\end{array}.& \left(21\right)\end{array}$

[0175] The three initial estimates can be combined in order to obtain the final estimate of x as in Equation (22):

[00025]$\begin{array}{cc}\begin{array}{c}\hat{x}=\frac{{\hat{x}}_{\mathrm{init},1}+{\hat{x}}_{\mathrm{init},2}+{\hat{x}}_{\mathrm{init},3}}{3}\\ =x+\frac{1}{3}(\frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\frac{h_2^{*}{h}_0-h_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\\ \frac{{}_1\left(h_0^{*}{h}_1+h_0{h}_2^{*}\right)}{2{.Math.h_0.Math.}^2}+\frac{{}_2\left(h_0^{*}{h}_2-h_0{h}_1^{*}\right)}{2{.Math.h_0.Math.}^2})x\\ =x+\mathrm{zx}\end{array}& \left(22\right)\end{array}$

where the scaling term z is given by Equation (23):

[00026]$\begin{array}{cc}Z=\frac{1}{3}\left(\frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\frac{h_2^{*}{h}_0-h_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\frac{{}_1\left(h_0^{*}{h}_1+h_0{h}_2^{*}\right)}{2{.Math.h_0.Math.}^2}+\frac{{}_2\left(h_0^{*}{h}_2-h_0{h}_1^{*}\right)}{2{.Math.h_0.Math.}^2}\right).& \left(23\right)\end{array}$

[0176] The noise term zx depends on both the information symbol x and the scaling term z. Since the propagation channels h.sub.0, h.sub.1 and h.sub.2 may be independent and random, their combination as in the expression (23) for z is expected to result in a variable with zero mean distribution as z(0, v.sub.z), where (0, v.sub.z) is a Gaussian distribution with mean zero and variance v.sub.z which will depend on the channel statistics and the combination of terms in Equation (23).

[0177] If the direct propagation channels h.sub.0 is much weaker than the propagation channels via the DCSs 106-1, 106-2, as it is customarily considered in DCSs, and as can be assessed after the channel estimation, then the receiver 104 may not take into account the terms proportional to h.sub.0 and the combining matrix Q is simplified as shown in Equation (24):

[00027]$\begin{array}{cc}Q=\left[\begin{array}{cc}{h}_1^{*}& h_2\\ h_2^{*}& -h_1\end{array}\right]& \left(24\right)\end{array}$

and the normalization matrix takes the form of Equation (25):

[00028]$\begin{array}{cc}N=\mathrm{diag}\left(\frac{1}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)},\frac{1}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\right).& \left(25\right)\end{array}$

[0178] Thereby, the initial estimates are given by Equation (26):

[00029]$\begin{array}{cc}\begin{array}{c}\left[\begin{array}{c}{\hat{x}}_{\mathrm{init},1}\\ {\hat{x}}_{\mathrm{init},2}\end{array}\right]={\mathrm{NQ}}^{*}y\\ =N\left[\begin{array}{ccc}{.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2& 0& h_1^{*}{h}_0+h_2{h}_0^{*}\\ 0& {.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2& h_2^{*}{h}_0-h_1{h}_0^{*}\end{array}\right]\left[\begin{array}{c}{}_{1}x\\ {}_{2}x\\ x\end{array}\right]\\ =\left[\begin{array}{ccc}1& 0& \frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\\ 0& 1& \frac{h_2^{*}{h}_0-h_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\end{array}\right]\left[\begin{array}{c}x\\ x\\ x\end{array}\right]\end{array},& \left(26\right)\end{array}$

and the final estimate of the information symbol x is given by Equation (27):

[00030]$\begin{array}{cc}\begin{array}{c}\hat{x}=\frac{{\hat{x}}_{\mathrm{init},1}+{\hat{x}}_{\mathrm{init},2}-}{2}\\ =x+\frac{1}{2}\left(\frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\frac{h_2^{*}{h}_0-h_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\right)x\\ =x+\mathrm{zx}\end{array}& \left(27\right)\end{array}$

where the term z is given by Equation (28):

[00031]$\begin{array}{cc}z=\frac{1}{2}\left(\frac{h_1^{*}{h}_0+h_2{h}_0^{*}}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}+\frac{h_2^{*}{h}_0-h_1{h}_0^{*}}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)}\right).& \left(28\right)\end{array}$

[0179] In this case, since h.sub.0 is weak and since h.sub.0 or its conjugate h*.sub.0 multiplies each of the terms in Equation (28), then z given by Equation (28) is also expected to be weak. In other words, the term zx is much smaller than x, which further facilitates improving the estimate of the information symbol x from Equation (27).

[0180] Optionally, Additive White Gaussian Noise (AWGN), which is always present in a received signal, may be added to the received signal vector in Equation (15) in order to estimate the information symbol x. Thereby, the processing for combining with Q, normalizing with N and combining the initial estimates to obtain the final estimate of x as disclosed above, also takes into account additional noise terms having lower magnitude than x.

[0181] In this example, as explained above, .sub.1 and .sub.2 have been considered as having a general, complex value. The value of .sub.1 and .sub.2 may be assigned depending on the capabilities or properties of the at least one DCS 106-1, 106-2. For example, for DCSs that only provide control of scattering phase shifts, the values of .sub.1 and .sub.2 may be of unit magnitude. Given specific values of .sub.1 and .sub.2, further simplifications or modifications of the channel estimation and of the estimation of the information symbol x at the at least one receiver 104 can be implemented.

[0182] In a further example, the at least one receiver 104 may combine the received signals by processing the received signal vector y of Equation (15) via a pseudoinverse of H, denoted by H.sup. and may further compute the initial estimates as in Equation (29):

[00032]$\begin{array}{cc}\left[\begin{array}{c}{\hat{x}}_{\mathrm{init},1}\\ {\hat{x}}_{\mathrm{init},2}\\ {\hat{x}}_{\mathrm{init},3}\end{array}\right]=H^{}y.& \left(29\right)\end{array}$

[0183] FIG. 7 shows a schematic diagram of another example of a wireless communication system 100, which builds on the exemplary embodiment shown in FIG. 4. Same elements are labelled with the same reference signs. In this example, the wireless communication system 100 may comprise the controller 110, one transmitter 102 with one transmitter antenna, one receiver 104 with one receiver antenna and a single DCS 106. The DCS 106 may comprise a scattering surface 107, and the scattering surface 107 may comprise a set of scattering elements 108.

[0184] The controller 110 may be configured to determine the STDC 112. That is, the controller 110 may be configured to determine the STDC matrix B. In this example, the total number of DCS is D=1 and it may be considered that T.sub.max=2 and =2, which meets the requirement of D. The STDC matrix B may be based on the Alamouti STBC matrix in Equation (12) with values .sub.1=.sub.2=1 and ignoring the second column, given in Equation (30):

[00033]$\begin{array}{cc}B=\left[\begin{array}{c}{}_1\\ -{}_2^{*}\end{array}\right]=\left[\begin{array}{c}1\\ -1\end{array}\right].& \left(30\right)\end{array}$

[0185] Then, the controller 110 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the transmitter 102, to the receiver 104 and to the DCS.

[0186] The controller 110 may be configured to determine the STDC matrix B offline, and may send the STDC matrix B, by signaling to the transmitter 102, to the receiver 104 and to the DCS 106 before the transmitter 102 transmits the coded radiofrequency signal to the receiver 104 during the plurality of time slots 116.

[0187] Alternatively, the controller 110, the transmitter 102, the receiver 104, additionally or alternatively the DCS 106 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the controller 110 may be configured to send by signaling to the transmitter 102, to the receiver 104 and to the DCS 106, a code identifier. The code identifier may comprise information that specifies the STDC matrix B in Equation (30) of the one or more potential STDC matrices B stored in a lookup table to be used. The indication information may be implemented, for example, by an index that may specify that the STDC matrix B in Equation (30) of the one or more STDC matrices B in the table is to be used.

[0188] The controller 110 may be further configured to determine the base phase shift configuration matrix .sub.d for the DCS 106, for example by any arbitrary, or random manner, or from a predefined list or using any available previous knowledge of the DCS 106 or a priori information about the propagation channels.

[0189] Then, the controller 110 may control, based on the STDC 112, the set of scattering elements 108 of the DCS d=1 106 during the T=2 time slots 116. That is, for each time slot 116 t.sub.i{t.sub.1, t.sub.2} of the T=2 time slots, the controller 110 may be configured to determine the coded configuration for the DCS d=1 by setting a scattering pattern equal to B.sub.i,d F.sub.d (.sub.d)=.sub.d F.sub.d (.sub.d), with .sub.d=B.sub.i,d, where B.sub.i,d is the entry in the i-th row and d-th column of matrix B and F.sub.d (.sub.d) is the scattering pattern of the DCS d 106.

[0190] Since the first (and only) column of matrix B in Equation (30) is [.sub.1, *.sub.2].sup.T=[1, 1].sup.T, then at the time slot t.sub.1 the code for the DCS sets .sub.1=1, and the coded configuration for the DCS d=1 106 is equal to the scattering pattern F.sub.1(.sub.1). At the time slot t.sub.2, it is obtained .sub.1=1 and, thus, the coded configuration for the DCS is equal to F.sub.1 (.sub.1). The scattering pattern via the DCS 106 and the propagation channel via the DCS 106 are as shown in Table 5, where

[00034]$h_1=h_{1,1,1}=h_{{\mathrm{DCS}}_1.fwdarw.\mathrm{RX}}^T{F}_1\left({}_1\right)h_{\mathrm{TX}.fwdarw.{\mathrm{DCS}}_1}.$

TABLE-US-00005 TABLE 5 Scattering Pattern Channel via DCS 1 DCS 1 Time slot t.sub.1 .sub.1F.sub.1(.sub.1 = F.sub.1(.sub.1) g.sub.1 = .sub.1h.sub.1 = h.sub.1 Time slot t.sub.2 .sub.2*F.sub.1(.sub.1) = F.sub.1(.sub.1) g.sub.1 = .sub.2*h.sub.1 = h.sub.1

[0191] Then, the controller 110 may be configured to control, based on the STDC 112, the transmitter 102 to generate a coded radiofrequency signal during the plurality of time slots 116. That is, for each time slot 116 t.sub.1, t.sub.2, the transmitter 102 may be configured to transmit an information symbol x in the coded radiofrequency signal, where the coded radiofrequency signal may comprise the transformation of the information symbol x based on the STDC matrix B, f.sub.TX (x, B, t.sub.i).

[0192] For the STDC matrix B specified in Equation (30), the transmitter 102 may be configured to send the information symbol x at the time slot 116 t.sub.1, since the entries of the first row of the STDC matrix B is {.sub.1}{.sub.1, .sub.2, 0}, and the transmitter 102 may be configured to send the x* at the time slot 116 t.sub.2, since the second row of the STDC matrix B is {*.sub.2}{*.sub.1, *.sub.2, 0}).

[0193] The resulting one or more direct propagation channels and one or more propagation channels via the DCS 106 between the transmitter 102 and the receiver 104, as well as the transmitted and received signals for each time slot 116 are shown in Table 6.

TABLE-US-00006 TABLE 6 Transmitted Direct Channel symbol .sub.1 channel via DCS 1 Received signal Training p 1 h.sub.0 h.sub.1 y.sub.p.sub.1 = (h.sub.0 + h.sub.1)p time slot Training p 1 h.sub.0 h.sub.1 y.sub.p.sub.2 = (h.sub.0 h.sub.1)p time slot Time slot x .sub.1 = 1 h.sub.0 .sub.1h.sub.1 = h.sub.1 y.sub.t.sub.1 = (h.sub.0 + h.sub.1)x t.sub.1 Time slot x* .sub.2* = 1 h.sub.0 .sub.2*h.sub.1 = h.sub.1 y.sub.t.sub.2 = (h.sub.0 h.sub.1)x* t.sub.2

[0194] The transmitter 102 may send pilot symbols p using extra time slots. The transmitted pilots may be known at the receiver 104. The receiver 104 may use the transmitted pilots together with the received signals y.sub.p.sub.1, y.sub.p.sub.2 and then may estimate the one or more channels via the DCS 106, h.sub.1, additionally or alternatively the one or more direct channels h.sub.0 as disclosed above in the previous examples. The estimated one or more channels 114 are scalars, thereby their estimation is easier compared to estimating channels whose size depends on the number of scattering elements 108 of the DCS 106, as it is the case in customary algorithms that use DCSs.

[0195] The received signal vector y after conjugation of the signal received by the receiver 104 in after the second time slot t.sub.2 is given in Equation (31):

[00035]$\begin{array}{cc}y=\left[\begin{array}{c}{y}_{t_1}\\ y_{t_2}^{*}\end{array}\right]=\left[\begin{array}{cc}{h}_1& h_0\\ h_0^{*}& -h_1^{*}\end{array}\right]\left[\begin{array}{c}x\\ x\end{array}\right]=H\left[\begin{array}{c}x\\ x\end{array}\right].& \left(31\right)\end{array}$

[0196] Then, a combining matrix Q can be easily computed as in Equation (32):

[00036]$\begin{array}{cc}Q=H^{*}=\left[\begin{array}{cc}{h}_1^{*}& h_0\\ h_0^{*}& -h_1\end{array}\right].& \left(32\right)\end{array}$

[0197] The matrix Q of Equation (32) can be applied to the received signal vector y, as shown in Equation (33):

[00037]$\begin{array}{cc}\mathrm{Qy}=\left[\begin{array}{cc}{h}_1^{*}& 0\\ h_0^{*}& -h_1\end{array}\right]\left[\begin{array}{cc}{h}_1& 0\\ h_0^{*}& -h_1^{*}\end{array}\right]\left[\begin{array}{c}x\\ x\end{array}\right]=\left[\begin{array}{cc}{.Math.h_1.Math.}^2+{.Math.h_0.Math.}^2& 0\\ 0& {.Math.h_1.Math.}^2+{.Math.h_0.Math.}^2\end{array}\right]\left[\begin{array}{c}x\\ x\end{array}\right]& \left(33\right)\end{array}$

which after being normalized, by multiplying all the terms by

[00038]$\frac{1}{\left({.Math.h_1.Math.}^2+{.Math.h_0.Math.}^2\right)},$

gives two initial estimates {circumflex over (x)}.sub.init,1, {circumflex over (x)}.sub.init,2 of the transmitted symbol x given in Equation (34):

[00039]$\begin{array}{cc}\left[\begin{array}{c}{\hat{x}}_{\mathrm{init},1}\\ {\stackrel{}{x}}_{\mathrm{init},2}\end{array}\right]=\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]\left[\begin{array}{c}x\\ x\end{array}\right]& \left(34\right)\end{array}$

that are averaged to obtain the final estimate of symbol x as in Equation (35):

[00040]$\begin{array}{cc}\stackrel{}{x}=\frac{{\stackrel{}{x}}_{\mathrm{init},1}+{\stackrel{}{x}}_{\mathrm{init},2}}{2}=x.& \left(35\right)\end{array}$

[0198] Optionally, AWGN can be added to the received signal vector in Equation (31), which includes an additional noise term in the Equations above.

[0199] FIG. 8a) shows a schematic diagram of another example of a wireless communication system 100, which builds on the exemplary embodiment shown in FIG. 4. Same elements are labelled with the same reference signs. In this example, the wireless communication system 100 may comprise the controller 110, two transmitters 102-1, 102-2, two transmitter antennas i.e., n=1,2, each transmitter having a single transmitter 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 comprise a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may comprise a set of scattering elements 108-1, 108-2.

[0200] The controller 110 may be configured to determine the STDC 112. That is, the controller 110 may be configured to determine the STDC matrix B. In this example, D=2 and it may be considered that T.sub.max=2 and =2, which meets the requirement of D. The STDC matrix B may be chosen as the Alamouti STBC matrix given in Equation (12) above.

[0201] Then, the controller 110 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the transmitters 102-1, 102-2, to the receiver 104 and to the DCSs 106-1, 106-2. Additionally or alternatively, the controller 110 may send by signaling to each DCS 106-1, 106-2 the respective d-th column of the STDC matrix B and the total number T of the plurality of time slots 116.

[0202] The controller 110 may be configured to determine the STDC matrix B offline, and may send the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling to the transmitters 102-1, 102-2, to the receiver 104 and to the DCSs 106-1, 106-2 before each transmitter 102-1, 102-2 transmits a coded radiofrequency signal to the receiver 104 during the plurality of time slots 116.

[0203] Alternatively, the controller 110, the transmitters 102-1, 102-2, the receiver 104, additionally or alternatively the DCSs 106-1, 106-2 may be configured to store one or more tables comprising one or more STDC matrices B. Then, the controller 110 may be configured to send by signaling to the transmitters 102-1, 102-2, to the receiver 104 and to the DCSs 106-1, 106-2, a code identifier. The code identifier may comprise information that specifies the STDC matrix B provided in Equation (12) of the one or more STDC matrices B stored in a lookup table to be used. The indication information may be implemented, for example, by an index that may specify the STDC matrix B provided in Equation (12) of the one or more STDC matrices B in the table to be used.

[0204] The controller 110 may be further configured to determine the base phase shift configuration matrix .sub.d for each DCS d 102-1, 102-2, for example in an arbitrary, or random manner, or from a predefined list or using any available previous knowledge of the DCSs 106-1, 106-2.

[0205] Then, the controller 110 may control, based on the STDC 112, the set of scattering elements 108-1, 108-2 of the DCS 106-1, 106-2 during the T=2 time slots 116, as disclosed above in the example of FIG. 6. The details are not repeated again.

[0206] The coded configuration for each DCS 106-1, 106-2 is independent of the number of transmitters 102-1, 102-2 and transmitter antennas and is also independent of the information symbols sent by the transmitters 102-1, 102-2. The coded configuration for each time slot 116 and for each DCS 106-1, 106-2 is the same as for the example of FIG. 6 and is shown in Table 1 above.

[0207] In this example, since there are two single antenna transmitters 102-1, 102-2 and two DCSs 106-1, 106-2, there may be a total of four propagation channels via the DCSs 106-1, 106-2 given in Equations (36) to (43):

[00041]$\begin{array}{cc}{h}_1=h_{1,1,1}=h_{{\mathrm{DCS}}_1.fwdarw.\mathrm{RX}}^T{F}_1\left({}_1\right)h_{{\mathrm{TX}}_1.fwdarw.{\mathrm{DCS}}_1}& \left(36\right)\end{array}$$\begin{array}{cc}{h}_2=h_{1,2,1}=h_{{\mathrm{DCS}}_2.fwdarw.\mathrm{RX}}^T{F}_2\left({}_2\right)h_{{\mathrm{TX}}_1.fwdarw.{\mathrm{DCS}}_2}& \left(37\right)\end{array}$$\begin{array}{cc}{h}_3=h_{1,1,2}=h_{{\mathrm{DCS}}_1.fwdarw.\mathrm{RX}}^T{F}_1\left({}_1\right)h_{{\mathrm{TX}}_2.fwdarw.{\mathrm{DCS}}_1}& \left(38\right)\end{array}$$\begin{array}{cc}{h}_4=h_{1,2,2}=h_{{\mathrm{DCS}}_2.fwdarw.\mathrm{RX}}^T{F}_2\left({}_2\right)h_{{\mathrm{TX}}_2.fwdarw.{\mathrm{DCS}}_2}& \left(39\right)\end{array}$$\mathrm{and}$$\begin{array}{cc}{g}_1=g_{1,1,1}={}_1{h}_{1,1,1}={}_1{h}_1& (40)\end{array}$$\begin{array}{cc}{g}_2=g_{1,2,1}={}_1{h}_{1,2,1}={}_1{h}_2& \left(41\right)\end{array}$$\begin{array}{cc}{g}_3=g_{1,1,2}={}_1{h}_{1,1,2}={}_3{h}_3& \left(42\right)\end{array}$$\begin{array}{cc}{g}_4=g_{1,2,2}={}_1{h}_{1,2,2}={}_4{h}_4& \left(43\right)\end{array}$

where Equation (3) has been used for obtaining g.sub.1, g.sub.2, g.sub.3, g.sub.4, which defines that for a DCS d 106-1, 106-2 with coded configuration equal to .sub.d F.sub.d (.sub.d), the resulting channel via the DCS d from a transmitter antenna n of one of transmitters 102-1 and 102-2, to the receiver antenna m of receiver 104 is g.sub.m,d,n=.sub.dh.sub.m,d,n.

[0208] The one or more propagation channels from the transmitters 102-1, 102-2 via the DCSs 102-1, 102-2 for each time slot 116 are shown in Table 7.

TABLE-US-00007 TABLE 7 Channel from Channel from Channel from Channel from TX 1 via DCS 1 TX 1 via DCS 2 TX 2 via DCS 1 TX 2 via DCS 2 g.sub.1 g.sub.2 g.sub.3 g.sub.4 Time slot t.sub.1 .sub.1h.sub.1 .sub.2h.sub.2 .sub.1h.sub.3 .sub.2h.sub.4 Time slot t.sub.2 .sub.2*h.sub.1 .sub.1*h.sub.2 .sub.2*h.sub.3 .sub.1*h.sub.4

[0209] As can be seen from Table 7, the propagation channels g.sub.1, g.sub.2, g.sub.3, g.sub.4 change as a function of the values of the STDC matrix B given in Equation (12), thus providing channel programming with the STDC 112.

[0210] Then, the controller 110 may be configured to control, based on the STDC 112, each transmitter 102-1, 102-2 to generate a coded radiofrequency signal during the plurality of time slots 116. That is, for each time slot 116 t.sub.i, each transmitter 102-1, 102-2 may be configured to transmit an information symbol x in the coded radiofrequency signal, where the coded radiofrequency signal may comprise a transformation of the information symbol x based on the STDC matrix B, denoted as f.sub.TX (x, B, t.sub.i).

[0211] The information symbol transmitted from each transmitter 102-1, 102-2 is denoted as x.sub.n, with n=1, 2. The two symbols x.sub.1 and x.sub.2 can be completely independent. Each transmitter 102-1, 102-2 may transmit the same information symbol x.sub.n in the coded radiofrequency signal during the two time slots 116 t.sub.1 and t.sub.2.

[0212] Using the STDC matrix B specified in Equation (12), for the time slot t.sub.1, the transmitter antenna n of transmitter 102-n may be configured to send the symbol x.sub.n since the entries of the first row of the STDC matrix B are {.sub.1, .sub.2}{.sub.1, .sub.2, 0}. For time slot t.sub.2, the transmitter antenna n of transmitter 102-n may be configured to send the symbol x*.sub.n at time slot t.sub.2, since the entries of the second row of the STDC matrix B are {*.sub.1, *.sub.2}{*.sub.1, *.sub.20}. The symbol transmitted by the transmitters 102-1, 102-2 for each time slot 116 is summarized in Table 8.

TABLE-US-00008 TABLE 8 Transmitted symbol Transmitted symbol from TX n = 1 from TX n = 2 Time slot t.sub.1 x.sub.1 x.sub.2 Time slot t.sub.2 x.sub.1* x.sub.2*

[0213] In the example of FIG. 8a), the transmitters 102-1, 102-2 may be further configured, based on the STDC 112, to transmit training pilots p during additional or training time slots. Said training pilots p transmitted during the training time slots may be needed for the receiver 104 in order to estimate the one or more propagation channels 114, in case that the estimates of the one or more propagation channels via the at least one DCS and/or one or more direct propagation channels are not yet available at the receiver 104.

[0214] Table 9 shows the coded radiofrequency signal transmitted by the transmitters 102-1, 102-2 including the extra time slots for transmission of training pilots p, for the two time slots 116 t.sub.1, t.sub.2. The value of ad for each DCS 106-1, 106-2 is also shown in Table 9. During the two time slots t.sub.1 and t.sub.2, the value of da depends on the STDC matrix B. During the training time slots, the controller 110 may be configured to control the set of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 by setting values of aa, for example, in a predetermined manner. The resulting direct propagation channels between the transmitters 102-1, 102-2 and the receiver 104 denoted as h.sub.0,1, h.sub.0,2, and the propagation channels via the two DCSs 106-1 106-2 are also shown in Table 9.

TABLE-US-00009 TABLE 9 Transmitted symbol DCS channels TX 1 TX 2 .sub.1 .sub.2 g.sub.1 g.sub.2 g.sub.3 g.sub.4 Received signal Training p 0 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.1 = time slot (h.sub.0, 1 + h.sub.1 + h.sub.2)p Training p 0 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.2 = time slot (h.sub.0, 1 + h.sub.1 h.sub.2)p Training p 0 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.3 = time slot (h.sub.0, 1 h.sub.1 h.sub.2)p Training 0 p 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.4 = time slot (h.sub.0, 2 + h.sub.3 + h.sub.4)p Training 0 p 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.5 = time slot (h.sub.0, 2 + h.sub.3 h.sub.4)p Training 0 p 1 1 h.sub.1 h.sub.2 h.sub.3 h.sub.4 y.sub.p.sub.6 = time slot (h.sub.0, 2 h.sub.3 h.sub.4)p Time x.sub.1 x.sub.2 .sub.1 .sub.2 .sub.1h.sub.1 .sub.2h.sub.2 .sub.1h.sub.3 .sub.2h.sub.4 y.sub.t.sub.1 = slot t.sub.1 (h.sub.0, 1 + .sub.1h.sub.1 + .sub.2h.sub.2)x.sub.1 + (h.sub.0, 2 + .sub.1h.sub.3 + .sub.2h.sub.4 )x.sub.2 Time x.sub.1* x.sub.2* .sub.2* .sub.1* .sub.2*h.sub.1 .sub.1*h.sub.2 .sub.2*h.sub.3 .sub.1*h.sub.4 y.sub.t.sub.2 = slot t.sub.2 (h.sub.0, 1 .sub.2*h.sub.1 + .sub.1*h.sub.2)x.sub.1* + (h.sub.0, 2 .sub.2*h.sub.3 + .sub.1*h.sub.4)x.sub.2*

[0215] The transmitted pilots p may be known at the receiver 104. Then, for each training time slot, the receiver 104 may be configured to estimate the one or propagation channels via the DCS 106-1, 106-2, h.sub.1, h.sub.2, h.sub.3, h.sub.4, additionally or alternatively the one or more direct propagation channels h.sub.0,1, h.sub.0,2 based on the received training pilots p and on the received signals y.sub.p.sub.1, y.sub.p.sub.2, y.sub.p.sub.3, y.sub.p.sub.4, y.sub.p.sub.5 and y.sub.p.sub.6. The propagation channels 114 are scalars, and their estimation is easier compared to estimating channels whose size depends on the number of scattering elements 108-1, 108-2 of each DCS 106-1 106-2, as in customary algorithms that use DCSs.

[0216] Further, for each time slot 116 t.sub.1, t.sub.2, the receiver 104 may be configured to determine the information symbols x.sub.n transmitted by one of the transmitters 102-1, 102-2 based on the STDC 112, based on the received coded radiofrequency signals, 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.

[0217] To that end, the receiver 104 may proceed as follows. The received signal vector y is constructed by stacking the signal received at the first time slot, namely y.sub.t.sub.1 and using the conjugate of the signal received at the second time slot, namely

[00042]$y_{t_2}^{*}.$

The signal received in the second time slot is conjugated because the information symbols transmitted in the second time slot were sent as the conjugates x*.sub.1 and x*.sub.2. Following this approach, the received signal vector y may take the form of Equation (44):

[00043]$\begin{array}{cc}y=\left[\begin{array}{c}{y}_{t_1}\\ y_{t_2}^{*}\end{array}\right]=\left[\begin{array}{cccccc}{h}_1& h_2& h_{0,1}& h_3& h_4& h_{0,2}\\ h_2^{*}& -h_1^{*}& h_{0,1}^{*}& h_4^{*}& -h_3^{*}& h_{0,2}^{*}\end{array}\right]& \left(44\right)\end{array}$

[0218] Since h.sub.0,1, h.sub.0,2, h.sub.1, h.sub.2, h.sub.3 and h.sub.4 have been estimated by the receiver 104, the overall channel matrix H can be constructed as in Equation (45):

[00044]$\begin{array}{cc}H=\left[\begin{array}{cccccc}{h}_1& h_2& h_{0,1}& h_3& h_4& h_{0,2}\\ h_2^{*}& -h_1^{*}& h_{0,1}^{*}& h_4^{*}& -h_3^{*}& h_{0,2}^{*}\end{array}\right]& \left(45\right)\end{array}$

[0219] The channel matrix of Equation (45) can be used to write the received signal vector as Equation (46):

[00045]$\begin{array}{cc}y={H\left[{}_1{x}_1,{}_2{x}_1,x_1,{}_1{x}_2,{}_2{x}_2,x_2\right]}^T& \left(46\right)\end{array}$

[0220] A combining matrix Q and a normalizing matrix N can be computed as shown in Equation (47) and Equation (48) respectively,

[00046]$\begin{array}{cc}Q=H^{*}& \left(47\right)\end{array}$$\begin{array}{cc}N=\mathrm{diag}\left(\frac{1}{{}_1\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)},\frac{1}{{}_2\left({.Math.h_1.Math.}^2+{.Math.h_2.Math.}^2\right)},\frac{1}{2{.Math.h_{0,1}.Math.}^2},\frac{1}{{}_1\left({.Math.h_3.Math.}^2+{.Math.h_4.Math.}^2\right)},\frac{1}{{}_2\left({.Math.h_3.Math.}^2+{.Math.h_4.Math.}^2\right)},\frac{1}{2{.Math.h_{0,2}.Math.}^2}\right)& \left(48\right)\end{array}$

where H* is used to denote the transpose conjugate of H. Using the received signal vector y in Equation (44), the combining matrix Q in Equation (47) and the normalizing matrix N in Equation (48), three initial estimates .sub.init,1, .sub.init,2, .sub.init,3 of the transmitted symbol x.sub.1 and three initial estimates .sub.init,1, .sub.init,2, .sub.init,3 of the transmitted symbol x.sub.2 can be obtained as in Equation (49):

[00047]$\begin{array}{cc}\left[\begin{array}{c}{\mathrm{init},1}_{}\\ {\mathrm{init},2}_{}\\ {\mathrm{init},3}_{}\\ {\mathrm{init},1}_{}\\ {\mathrm{init},2}_{}\\ {\mathrm{init},3}_{}\end{array}\right]=\mathrm{NQy}.& \left(49\right)\end{array}$

[0221] The three initial estimates .sub.init,1, .sub.init,2, .sub.init,3 can be combined to obtain the final estimate of x.sub.1 given in Equation (50):

[00048]$\begin{array}{cc}\begin{array}{c}=\frac{1}{3}\underset{i=1}{\overset{3}{.Math.}}{\mathrm{init},i}_{}\\ =x_1+z_1\end{array}& \left(50\right)\end{array}$

[0222] Similarly, the three initial estimates .sub.init,1, .sub.init,2, .sub.init,3 can be combined to obtain the final estimate of x.sub.2 given in Equation (51):

[00049]$\begin{array}{cc}\begin{array}{c}=\frac{1}{3}\underset{i=1}{\overset{3}{.Math.}}{\mathrm{init},i}_{}\\ =x_2+z_2\end{array}& \left(51\right)\end{array}$

[0223] Since the propagation channels h.sub.0,1, h.sub.0,2, h.sub.1, h.sub.2, h.sub.3 and h.sub.4 are independent random variables, the resulting noise terms z.sub.1 and z.sub.2 in Equations (50) and (51) are expected to be Gaussian random variables with zero mean distribution, z.sub.1(0, v.sub.z.sub.1) and z.sub.2(0, v.sub.z.sub.2). It is expected that as the number of at least one transmitters in the wireless communication system 100 increases, the variance of these noise terms decreases and the values of z.sub.1 and z.sub.2 get very close to their mean, i.e., very close to zero. This may provide further advantages when the wireless communication system 100 may comprise multiple low complexity transmitters, for example multiple independent IoT devices.

[0224] Adaptation to multiple antenna transmitters is straightforward following the example of FIG. 8a) with two transmitters, as depicted in FIG. 8b). FIG. 8b) shows an example of a wireless communication system 100, which builds on the exemplary embodiment shown in FIG. 4, for a case with a single transmitter 102 with two transmitter antennas. Same elements are labelled with the same reference signs. Following the example of FIG. 8a), the same propagation channels as in Table 7 are obtained, the same transmitted symbols per antenna as in Table 8 and Table 9 are obtained, and same received signals as in Table 9 are obtained. The signal processing at the receiver 104 is the same as described in relation to Equation (44) to Equation (51).

[0225] Extension to more than two transmitters is straightforward following the examples of FIG. 8a) with two transmitters 102-1 102-2 and FIG. 8b) with multiple antenna transmitter. FIG. 9 shows a schematic diagram of a further example of a wireless communication system 100, which builds on the exemplary embodiment shown in FIG. 4. Same elements are labelled with the same reference signs. In this example, the wireless communication system 100 may comprise the controller 110, a transmitter 102, with a single transmitter antenna n=1, a receiver 104, with a single receiver 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 comprise a scattering surface 107-1, 107-2, 107-3, and each scattering surface 107-1, 107-2, 107-3 may comprise a set of scattering elements 108-1, 108-2, 108-3.

[0226] The controller 110 may be configured to determine the STDC 112. That is, the controller 110 may be configured to determine the STDC matrix B. In this example, D=3 and it may be considered that T.sub.max=4 and =3, which meets the requirement of D. A STBC matrix that maps three complex values {.sub.1, .sub.2, .sub.67 =3} onto a TD matrix B such that TT.sub.max is given in Equation (52):

[00050]$\begin{array}{cc}B=\left[\begin{array}{ccc}{}_1& {}_2& {}_3\\ -{}_2^{*}& {}_1^{*}& 0\\ {}_3^{*}& 0& -{}_1^{*}\\ 0& {}_3^{*}& -{}_2^{*}\end{array}\right].& \left(52\right)\end{array}$

[0227] The matrix B given in Equation (52) meets the constraint that the entries of a given row belong to either to {.sub.1, .sub.2, .sub.3, 0} or to {*.sub.1, *.sub.2, *.sub.3, 0} but not to both. This is easily verifiable by inspection. The quantities .sub.1, .sub.2, and .sub.3 are kept generally as scalar complex values.

[0228] Further, the controller 110 may be configured to send the total number T of the plurality of time slots 116 and the STDC matrix B by signaling to the transmitter 102, to the receiver 104 and to the DCSs 106-1, 106-2, 106-3. Alternatively, instead of the full STDC matrix B, the controller 110 may send by signaling to each DCSs 106-1, 106-2, 106-3 the respective d-th column of the STDC matrix B and the total number T of the plurality of time slots 116.

[0229] The controller 110 may be configured to determine the STDC matrix B offline, and may send the STDC matrix B in Equation (52), additionally or alternatively the d-th column of the STDC matrix B, by signaling to the transmitter 102, to the receiver 104 and to the DCSs 106-1, 106-2, 106-3 before the transmitter 102 transmits the coded radiofrequency signal to the receiver 104 during the plurality of time slots 116.