Wireless communication system and method

Abstract

The present disclosure provides a wireless communications system comprising at least one DCS having a surface with scattering elements having a controllable phase shift, at least one transmitter configured to transmit coded radio frequency signals to at least one receiver during a plurality of time slots, and a controller. The controller controls the at least one transmitter to generate coded radio frequency signals during the plurality of time slots based on a space-time DCS code (STDC). The controller further controls a set of scattering elements of the at least one DCS during the plurality of time slots based on the STDC. The STDC is configured to limit the total number of the at least one DCS and the maximum number of the plurality of time slots, T max Depends on.

Description

[Technical Field]

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

[0002] In currently deployed wireless communication systems, the wireless channel cannot be controlled, and therefore, wireless communication between a transmitter (TX) and a receiver (RX) is achieved by an algorithm that adapts the TX and RX to given channel conditions. Recent research has proposed a new paradigm for wireless communication in which the channel is also controllable by introducing large intelligent surfaces (LIS), also known as reconfigurable intelligent surfaces (RIS) or reflective intelligent surfaces (RIS), into the propagation environment for use as digitally controllable scatterers (DCS). DCS allows for the modification of part of the propagation path of the wireless channel, thus enabling the possibility of having a programmable wireless channel, where different algorithms can be used to adapt part of the propagation path to improve wireless communication between the TX and RX. Therefore, in this new paradigm, wireless communication between the TX and RX is achieved by an algorithm that programs not only the TX and RX but also the wireless channel to achieve the required communication.

[0003] Most algorithms for channel programming using a DCS require channel state information (CSI) for DCS configuration. However, obtaining this CSI can be time-consuming and require significant overhead due to the large number of adjustable elements that are part of the DCS. Generally, a DCS is implemented using a large number of reflective or scattering elements, typically hundreds or thousands, arranged on a surface, as shown in FIG. 1. Non-flat configurations of the DCS surface, as shown in FIG. 2a, and the distributed configuration exemplarily shown in FIG. 2b, are also useful for implementing a DCS. Multiple DCSs can also be implemented by logically splitting a DCS into multiple DCSs using subsets of scattering elements. Each scattering element provides the ability to control the phase of its scattered signal. The scattering phase of a scattering element s of a DCS d is defined as φ. d,s The total S that makes up DCSd is expressed as d Controllable scattering phase configuration matrix of scattering elements

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[0004] Channel Components

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[0005] A large matrix needs to be calculated: the channel matrix

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[0006] Feedback is required. DCSs are assumed to be low-capability devices, and therefore they contain no RF chains or only a limited number of RF chains. As a result, channel estimation cannot be performed in the DCS, but is typically performed in the RX. DCS phase φ d is the measured channel

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[0000] . Some reduction in feedback overhead has been proposed by successive refinement algorithms, but these have the problem of requiring multiple pilots, channel estimation, and feedback. Even if the amount of feedback can be reduced by using a codebook, in scenarios with low channel coherence time, the delay in feeding back information can be detrimental to system performance.

[0007] Although the benefits of DCS for communication improvement, e.g., coverage improvement, have been demonstrated, most of the proposed algorithms suffer from the two problems mentioned above, namely, the complexity of CSI acquisition and feedback.

[0008] A solution to the large CSI requirement and feedback overhead is proposed, which is to reduce the DCS phase φ d Use a random configuration of φ d The random design of φ eliminates the need for CSI in DCS for phase configuration. d can be generated in the DCS, and therefore φ d The overhead of communicating the random phase to the DCS is also not required. The random phase in the DCS creates random channel propagation paths that are used opportunistically in a manner similar to opportunistic beamforming. The channel variations created may be limited when only one DCS is used, and therefore several DCSs may be required to generate a sufficient number of channel variations to achieve the desired multi-user diversity with the DCS random channel. Furthermore, although CSI is not required for DCS phase configuration, feedback delay is introduced because the channel link quality must be fed back from the users to the TX.

[0009] No CSI is required in DCS, and φ d Random phase φ for DCS configurations that do not require communicating d Nevertheless, randomly setting the phase without coordination between DCS elements may result in low energy at the receiver.

[0010] Space-time block coding (STBC) algorithms have been proposed to overcome the requirement of CSI estimation before data transmission. STBC is a code that is applied at the transmitter and does not require CSI at the transmitter. STBC is a code that is applied at the transmitter and does not require CSI at the transmitter. η} into a τ × μ matrix, i.e., a matrix with τ rows and μ columns. Most known STBC matrices are designed for encoding η symbols over μ transmit antennas and τ time slots, where τ ≥ μ and η ≤ μ. An example of an STBC is the Alamouti code, which corresponds to the cases η = 2, τ = 2, μ = 2, given by equation (2).

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[0011] A DCS is proposed that is illuminated by a dedicated transmitter antenna (the transmitter antenna transmits a single-tone carrier) using Alamouti coding. The information symbols {s1, s2} to be transmitted are communicated to the DCS (via a wired or dedicated connection), and then the DCS phase φ is adjusted so that the signal scattered by the DCS is a carrier tone with Alamouti coding of the symbols {s1, s2}. d Although CSI is not required in the DCS, the DCS needs to know the information symbols to be transmitted, which still adds overhead for the control of the DCS. Furthermore, only propagation paths through the DCS are used; thus, other non-DCS propagation paths (i.e., direct paths), if present, are not considered. Furthermore, because the DCS scattering elements primarily provide phase control, primarily symbols from a constellation with a constant amplitude can be transmitted. DCS elements that provide both amplitude and phase control may be more expensive to implement. Summary of the Invention

[0012] In view of the above, the present disclosure aims to overcome the problems of large CSI requirements and feedback overhead for DCS algorithms. The objective is to provide a wireless communication system and method that uses algorithms that reduce CSI knowledge and feedback requirements for communication enhancements using one or more DCSs.

[0013] This and other objects are achieved by the present disclosure according to the solutions set forth in the independent claims. Advantageous embodiments are further set forth in the dependent claims. [Means for solving the problem]

[0014] A first aspect of the present disclosure provides a wireless communications system comprising: at least one transmitter configured to transmit coded radio frequency signals to at least one receiver during a plurality of time slots; at least one digitally controllable scatterer (DCS), the DCS comprising a scattering surface including a set of scattering elements, each scattering element having a controllable phase shift; a controller; and at least one receiver configured to obtain, by reception, coded radio frequency signals transmitted by the at least one transmitter during the plurality of time slots. The controller controls the at least one transmitter to generate coded radio frequency signals during the plurality of time slots based on a space-time DCS code (STDC), and controls the set of scattering elements of the at least one DCS during the plurality of time slots based on the STDC, the coded radio frequency signals transmitted by the at least one transmitter during the plurality of time slots propagating from the at least one transmitter to the at least one receiver via one or more propagation channels, the one or more propagation channels including one or more propagation channels via the at least one DCS and / or one or more direct propagation channels, the STDC being a number that is proportional to the total number of the at least one DCS and the plurality of time slots. max It is configured to depend on

[0015] Thus, the STDC defines the configuration of at least one transmitter and at least one DCS during multiple time slots.

[0016] This offers the advantage of enabling STDC for DCS configuration, transmitter coded signal generation, and receiver processing without requiring CSI feedback or estimation of large channel matrices.

[0017] Further advantageously, the overhead in transmitting STDC may also be reduced, and efficiency may be increased.

[0018] In an embodiment of the first aspect, the STDC includes an STDC matrix B, and the STDC matrix B has dimensions T×D, where D is the total number of at least one DCS, D≧1, and T≦T max is the total number of time slots.

[0019] In an embodiment of the first aspect, the total number of the plurality of time slots is T max ≥ D, and the STDC matrix B is a set of δ ≤ D complex-valued {β1, β2,…, β δ}, and the entries of row i of matrix B are defined based on {±β1,±β2,…,±β δ ,0} or

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[0020] In particular, the STDC is independent of the number of scattering elements in at least one DCS, and therefore, efficiency can be increased and low overhead can be obtained.

[0021] In an embodiment of the first aspect, the sign of each of at least one DCS d, where d∈{1, 2, ..., D}, is determined by a respective d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is B d It is expressed as:

[0022] This provides the advantage that the sign of at least one DCS can be easily determined by selecting the respective column of the STDC matrix B.

[0023] In an embodiment of the first aspect, time slot t i ∈{t1,t2,…,t T}, the controller assigns the coding configuration of each of at least one DCS d, d∈{1, 2, …, D} to B i,d F d (φ d ) and F d (φ d ) is the scattering pattern of at least one DCSd, and φ d is the basic phase shift configuration matrix of at least one DCSd, and B i,d are the respective symbols B d represents the entry in the i-th row of

[0024] This means that the coding configuration of at least one DCS is d (φ d ), where the phase shift is α d =B i,d As a result, the phase-shifted scattering pattern α d F d (φ d ) the coverage of at least one DCS is d does not change the scattering pattern with respect to the energy sensed at each point in space, so F d (φ d ) can be used. This is beneficial because one or more propagation channels through at least one DCS can remain fixed even when coding is applied, with the primary change being their overall phase. As a result, by using STDC according to the present disclosure, at least one propagation path through at least one DCS can be formed, which can remain fixed for multiple time slots. This facilitates channel estimation and signal combining at at least one receiver.

[0025] Furthermore, programming the DCS according to the present disclosure has the advantage that information symbols are only required at at least one transmitter and not at least one DCS, which is an important distinction over the state of the art implementation of STBC Alamouti with DCS, where information symbols are required at the DCS for DCS programming, resulting in significant overhead for communication of information symbols to at least one DCS.

[0026] In an embodiment of the first aspect, t i ∈{t1,t2,…,t T} for each time slot t i , at least one transmitter transmits information symbols x in a coded radio frequency signal, the coded radio frequency signal including a transformation of the information symbols x based on an STDC matrix B, the transformation of the information symbols x being such that the entries of each ith row of the STDC matrix B are {±β1,±β2,...,±β δ , 0}, then time slot t i or the entry of each ith row of the STDC matrix B is

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[0027] The proposed STDC can be applied to multiple independent single-antenna transmitters and can also be applied to coding with only a single-antenna transmitter, a desirable feature in communication systems with low-complexity devices that require coding across at least two transmitter antennas and may not be able to implement STBC, such as Internet of Things (IoT) devices.

[0028] Further advantageously, this allows the symbols sent by the at least one transmitter to be obtained from constellations with different amplitudes.

[0029] In an embodiment of the first aspect, at least one receiver is configured to estimate one or more propagation channels via at least one DCS, additionally or alternatively one or more direct propagation channels.

[0030] In an embodiment of the first aspect, t i ∈{t1,t2,…,t T} for each time slot t i where the at least one receiver is further configured to determine information symbols x transmitted by the at least one transmitter based on STDC, based on the received coded radio frequency signal, and based on the estimated one or more propagation channels via the at least one DCS, additionally or alternatively based on the estimated one or more direct propagation channels.

[0031] The estimation of the information symbols x by the at least one receiver may be based on diversity combining, for example.

[0032] This provides the advantage that channel estimation can be performed and required only at the receiver, and therefore no feedback may be required. Furthermore, the number of entries of the estimated channel matrix is ​​proportional to the number of DCS scattering elements, S. d It does not depend on S d Much smaller than that.

[0033] In an embodiment of the first aspect, one of the controller, the at least one transmitter, the at least one receiver, or the at least one DCS is further configured to determine an 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, or send the respective d-th column of the STDC matrix B and the total number T of the plurality of time slots by signaling to at least one DCS d.

[0034] Since the STDC matrix B has only T×D elements, the overhead in signaling the STDC matrix B may be small.

[0035] Furthermore, further overhead reduction may be achieved by sending each dth column of the STDC matrix B instead of the complete STDC matrix B to at least one DCS.

[0036] In an embodiment of the first aspect, the STDC matrix B is determined offline and the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, is sent by signaling before at least one transmitter transmits the encoded radio frequency signal.

[0037] This provides the advantage that overhead can be further reduced and efficiency can be increased.

[0038] In an embodiment of the first aspect, the at least one transmitter and the at least one DCS are synchronized.

[0039] A second aspect of the present disclosure is a wireless communication method, comprising: controlling, by a controller, at least one transmitter to generate coded radio frequency signals during a plurality of time slots based on a space-time DCS code STDC; controlling, by the controller, a set of scattering elements of the at least one DCS during the plurality of time slots based on the STDC, wherein the at least one DCS comprises a scattering surface comprising the set of scattering elements, each of the scattering elements having a controllable phase shift; transmitting, by the at least one transmitter, the coded radio frequency signals during the plurality of time slots to at least one receiver; and obtaining, by the at least one receiver, the coded radio frequency signals transmitted by the at least one transmitter during the plurality of time slots by reception, the coded radio frequency signals transmitted by the at least one transmitter during the plurality of time slots, propagating from the at least one transmitter to the at least one receiver via one or more propagation channels, the one or more propagation channels including one or more propagation channels via the at least one DCS and / or one or more direct propagation channels, wherein the STDC is a number that is greater than or equal to a total number of the at least one DCS and a maximum number T of the plurality of time slots. max The present invention provides a wireless communication method that relies on

[0040] Thus, the STDC defines the configuration of at least one transmitter and at least one DCS during multiple time slots.

[0041] This offers the advantage of enabling STDC for DCS configuration, transmitter coded signal generation, and receiver processing without requiring CSI feedback or estimation of large channel matrices.

[0042] Further advantageously, the overhead in transmitting STDC may also be reduced, and efficiency may be increased.

[0043] In an embodiment of the second aspect, the STDC includes an STDC matrix B, and the STDC matrix B has dimensions T×D, where D is the total number of at least one DCS, D≧1, and T≦T max is the total number of time slots.

[0044] In an embodiment of the second aspect, the total number of the plurality of time slots is T max ≥ D, and the STDC matrix B is a set of δ ≤ D complex-valued {β1, β2,…, β δ}, and the entries of row i of matrix B are defined based on {±β1,±β2,…,±β δ ,0} or

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[0045] In particular, the STDC is independent of the number of scattering elements in at least one DCS, and therefore, efficiency can be increased and low overhead can be obtained.

[0046] In an embodiment of the second aspect, the sign of each of at least one DCS d, d∈{1, 2, ..., D}, is determined by a respective d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is B d It is expressed as:

[0047] This provides the advantage that at least the sign of the DCS can be easily determined by selecting the respective column of the STDC matrix B.

[0048] In an embodiment of the second aspect, the step of controlling, by the controller, the set of scattering elements of the at least one DCS during a plurality of time slots based on STDC includes controlling, by the controller, the set of scattering elements of the at least one DCS during a plurality of time slots based on STDC. i ∈{t1,t2,…,tT}, let B be the coding configuration of each of at least one DCSd where d∈{1, 2, …, D}. i,d F d (φ d ) as F d (φ d ) is the scattering pattern of at least one DCSd, and φ d is the basic phase shift configuration matrix of at least one DCSd, and B i,d are the respective symbols B d represents the entry in the i-th row of,.

[0049] This means that the coding configuration of at least one DCS is d (φ d ), where the phase shift is α d =B i,d As a result, the phase-shifted scattering pattern α d F d (φ d ) the coverage of at least one DCS is d does not change the scattering pattern with respect to the energy sensed at each point in space, so F d (φ d ) can be used. This is beneficial because one or more propagation channels through at least one DCS can remain fixed even when coding is applied, with the primary change being their overall phase. As a result, by using STDC according to the present disclosure, at least one propagation path through at least one DCS can be formed, which can remain fixed for multiple time slots. This facilitates channel estimation and signal combining at at least one receiver.

[0050] Furthermore, programming the DCS according to the present disclosure has the advantage that information symbols are only required at at least one transmitter and not at least one DCS, which is an important distinction over the state of the art implementation of STBC Alamouti with DCS, where information symbols are required at the DCS for DCS programming, resulting in significant overhead for communication of information symbols to at least one DCS.

[0051] In an embodiment of the second aspect, the step of controlling, by the controller, at least one transmitter to generate coded radio frequency signals during a plurality of time slots based on STDC includes controlling, by the at least one transmitter, t i ∈{t1,t2,…,t T} for each time slot t i , transmitting information symbols x in a coded radio frequency signal, the coded radio frequency signal including a transformation of the information symbols x based on an STDC matrix B, the transformation of the information symbols x being such that the entries of each ith row of the STDC matrix B are {±β1, ±β2, ..., ±β δ , 0}, then time slot t i or the entry of each ith row of the STDC matrix B is

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[0052] The proposed STDC can be applied to multiple independent single-antenna transmitters and can also be applied to coding with only a single-antenna transmitter, a desirable feature in communication systems with low-complexity devices, such as IoT devices, that require coding across at least two transmitter antennas and may not be able to implement STBC.

[0053] Further advantageously, this allows the symbols sent by the at least one transmitter to be obtained from constellations with different amplitudes.

[0054] In an embodiment of the second aspect, the method further comprises the step of estimating, by the at least one receiver, one or more propagation channels via the at least one DCS, additionally or alternatively one or more direct propagation channels.

[0055] In an embodiment of the second aspect, the method comprises: i ∈{t1,t2,…,t T} for each time slot t i and determining, by the at least one receiver, information symbols x transmitted by the at least one transmitter based on the received coded radio frequency signal based on STDC and based on estimated one or more propagation channels via the at least one DCS, additionally or alternatively based on estimated one or more direct propagation channels.

[0056] The estimation of the information symbols x by the at least one receiver may be based on diversity combining, for example.

[0057] This provides the advantage that channel estimation can be performed and required only at the receiver, and therefore no feedback may be required. Furthermore, the number of entries of the estimated channel matrix is ​​proportional to the number of DCS scattering elements, S. d It does not depend on S d Much smaller than that.

[0058] In an embodiment of the second aspect, the method further includes determining, by one of the controller, the at least one transmitter, the at least one receiver, or the at least one DCS, the STDC matrix B. Additionally, the method includes sending, by the at least one transmitter, the at least one receiver, or the at least one DCS, 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, or sending, by signaling to at least one DCS d, a respective d-th column of the STDC matrix B and the total number T of the plurality of time slots.

[0059] Since the STDC matrix B has only T×D elements, the overhead in signaling the STDC matrix B may be small.

[0060] Furthermore, further overhead reduction may be achieved by sending each dth column of the STDC matrix B instead of the complete STDC matrix B to at least one DCS.

[0061] In an embodiment of the second aspect, the method further comprises the steps of determining the STDC matrix B offline and sending the STDC matrix B, additionally or alternatively the d-th column of the STDC matrix B, by signaling before the at least one transmitter transmits the encoded radio frequency signal.

[0062] This provides the advantage that overhead can be further reduced and efficiency can be increased.

[0063] In an embodiment of the second aspect, the method further comprises the at least one transmitter and the at least one DCS being synchronized.

[0064] The method according to the second aspect includes features of the corresponding embodiment of the wireless communication system of the first aspect.

[0065] A third aspect of the present disclosure provides a computer program product comprising program code for, when executed on a processor, performing a method according to the second aspect or an embodiment thereof.

[0066] A computer program product according to the third aspect includes features of a corresponding embodiment of the method of the second aspect.

[0067] The method according to the second aspect and the computer program product according to the third aspect, and embodiments thereof, provide the same advantages and effects as described above for the wireless communication system of the first aspect and its respective embodiments.

[0068] The solution according to the present disclosure may provide the following advantages: · Enables diversity combining of different channel propagation paths even in scenarios where there is only a single antenna at the transmitter and receiver. The coding applied in at least one DCS is independent of the information symbols transmitted. With DCS greater flexibility in the type of channels generated can be achieved. · Feedback is not required.

[0069] It should be noted that all devices, elements, units, and means described in this application can be implemented with software or hardware elements, or any kind of combination thereof. All steps performed by various entities described in this application, and functions described as being performed by various entities, are intended to mean that the respective entities are adapted or configured to perform the respective steps and functions. In the following description of specific embodiments, even if a specific function or step performed by an external entity is not reflected in the description of the specific detailed element of that entity that performs the specific step or function, it should be apparent to those skilled in the art that these methods and functions can be implemented with respective software or hardware elements, or any kind of combination thereof.

[0070] The above-described aspects and embodiments are explained in the following description of specific embodiments in connection with the accompanying drawings. [Brief explanation of the drawings]

[0071] [Figure 1] An example of DCS is shown below. [Figure 2a] 1 illustrates an exemplary configuration of a non-flat DCS scattering surface. [Figure 2b] 1 illustrates an exemplary configuration of a dispersive DCS scattering surface. [Figure 3] 1 shows an exemplary signal propagating from a transmitter to a receiver via a DCS through a channel that is dependent on the transmitter to DCS channel, the DCS to receiver channel, and the scattering pattern of the DCS. [Figure 4] 1 shows a schematic diagram of a wireless communication system according to the present disclosure. [Figure 5] 1 illustrates an exemplary flowchart for generating space-time DCS codes according to the present disclosure. [Figure 6] 1 shows a schematic diagram of an example wireless communication system according to the present disclosure; [Figure 7]1 shows a schematic diagram of an example wireless communication system according to the present disclosure; [Figure 8a] 1 shows a schematic diagram of an example wireless communication system according to the present disclosure; [Figure 8b] 1 shows a schematic diagram of an example wireless communication system according to the present disclosure; [Figure 9] 1 shows a schematic diagram of an example wireless communication system according to the present disclosure; [Figure 10] 1 illustrates an example of information exchanged between a controller, one transmitter, two DCSs, and one receiver according to the present disclosure. [Figure 11] 10 illustrates another example of information exchanged between a controller, one transmitter, two DCSs, and one receiver according to the present disclosure. [Figure 12] 1 illustrates an example of information exchanged between a controller, one transmitter, D DCSs, and one receiver according to the present disclosure. [Figure 13a] 1 illustrates an example of a timeslot in a wireless communication system according to the present disclosure for four information symbols transmitted. [Figure 13b] 1 illustrates an example of a timeslot in a wireless communication system according to the present disclosure for four information symbols transmitted. [Figure 14] 1 illustrates a wireless communication method according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0072] 4 illustrates an exemplary embodiment of a wireless communication system 100 according to the present disclosure. The wireless communication system 100 comprises at least one transmitter 102 configured to transmit coded radio frequency signals to at least one receiver 104 during a plurality of time slots 116. The system 100 further comprises at least one DCS 106 having a scattering surface 107. The scattering surface 107 comprises a plurality of scattering elements 106, each scattering element 106 having a controllable phase shift. The system 100 further comprises a controller 110 and at least one receiver 104 configured to receive the coded radio frequency signals transmitted by the at least one transmitter 102 during the plurality of time slots 116.

[0073] The controller 110 is configured to control the at least one transmitter 102 to generate coded radio frequency signals during a plurality of time slots 116 based on the space-time DCS code STDC 112 .

[0074] Additionally, the controller 110 is configured to control the set of scattering elements 108 of the at least one DCS 106 during the plurality of time slots 116 based on the STDC 112. As a result, 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 based on the code STDC 112. Notably, the STDC 112 is independent of the number of scattering elements 108 of each of the at least one DCS, resulting in efficiency and low overhead.

[0075] STDC112 is the total number of at least one DCS106 and T max The maximum number of time slots 116 depends on the maximum number of time slots 116 represented as:

[0076] The coded radio frequency signals transmitted by the at least one transmitter 102 during the plurality of time slots 116 propagate from the at least one transmitter 102 to the at least one receiver 104 via one or more propagation channels 114. The one or more propagation channels 114 include one or more propagation channels via the at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 include one or more direct propagation channels. That is, the one or more propagation channels 114 include one or more propagation channels between the at least one transmitter 102 and the at least one receiver 102 via the at least one DCS 106. Additionally or alternatively, the one or more propagation channels 114 include one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver 104. For example, if a direct propagation channel between at least one transmitter 102 and at least one receiver is blocked, the one or more propagation channels 114 may not include the direct propagation channel between at least one transmitter 102 and at least one receiver.

[0077] The STDC 112 includes an STDC matrix B. The STDC matrix B has dimensions T×D, where D is the total number of at least one DCS 106, D≧1, and T≦T max is the total number of the plurality of time slots 116, the maximum number of the plurality of time slots 116 is less than or equal to the total number of DCSs 106, and T max ≧D.

[0078] The STDC matrix B is a set of δ complex values ​​{β1,β2,…,β δ}, where the number of complex values ​​is less than or equal to the total number of DCSs 106, i.e., δ≦D. The entries of row i of the STDC matrix B are {±β1, ±β2, ..., ±β δ ,0} or

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[0079] The STDC matrix B can be derived from a conventional STBC matrix. An example flowchart for generating the STDC matrix B according to the present disclosure is shown in FIG.

[0080] In step S502, the flowchart takes as input the total number of DCSs, D, and the maximum number of time slots 106 available or allowed for STDC, T max ≧D.

[0081] Next, in step S504, δ≦D complex values ​​{β1, β2, ..., β δ} to a T×D matrix B, where T≦T max The matrix B is such that the entries of any row i of B are {±β1,±β2,…,±β δ ,0} or

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[0082] In step S506, the STDC matrix B may be determined by assigning the matrix selected in step S504 thereto. The example flowchart of Figure 5 may provide the STDC matrix B as an output.

[0083] Referring to FIG. 4, the code of each of the at least one DCS d106, where d∈{1, 2, ..., D}, is determined by the respective d-th column of the STDC matrix B. d The d-th column of the STDC matrix B, represented as:

[0084] That is, for a total of D DCSs 106, the code of the dth DCS 106 (which may be referred to as DCSd hereinafter in this disclosure), where d∈{1, 2, ..., D}, is specified by the dth column of the STDC matrix B. As a result, a given DCSd 106 only requires knowledge of the corresponding column d of B.

[0085] Then, a plurality of time slots 116, t i ∈{t1,t2,…,t T , D}, the controller 110 assigns the coding configuration of each of at least one DCS 106d, where d∈{1, 2, ..., D}, to B i,d F d (φ d ) and F d (φ d ) is the scattering pattern of at least one DCSd106, and φ d is the basic phase shift configuration matrix of at least one DCSd106, and B i,d are the respective symbols B d represents the entry of the i-th row of B, i.e., i,d is the entry in the ith row and dth column of the STDC matrix B.

[0086] By controlling the set of scattering elements 108 of at least one DCS 106 during multiple time slots 116 based on the STDC 112, the controller 110 may select the dth column of the STDC matrix B and control the at least one DCS 106d to further determine the above-mentioned coding configuration. Additionally or alternatively, the controller 110 may control the at least one DCS 106 during multiple time slots 116 to apply the determined coding configuration.

[0087] At least one DCSd106 basic phase shift configuration matrix φ d can be determined locally at the corresponding DCS d 106. Thus, each DCS d 106 can determine φ in an independent and uncoordinated manner without any signaling requirements. d Alternatively, the controller may determine φ for each of the DCSd 106. d may be configured to determine each φ by signaling. d may be sent to each DCSd 106.

[0088] Time slot t i The coding configuration of each of the at least one DCS 106d between i,d F d (φ d )=α d F d (φ d ) that is, each coding configuration of at least one DCS 106d is a scattering pattern F d (φ d ), where the scaling is α d When the entries of the STDC matrix B are all unit magnitude, the scattering pattern F d (φ d ) by a complex scalar α d Since is a unit size, α d F d (φ d ) coverage of at least one DCSd106 when using F d (φ d ), and therefore α d The scaling by the scattering pattern F d (φ d ) corresponds to applying a phase shift to the scattering pattern F d (φ dRotating the α sigma does not change the scattering pattern in terms of the energy sensed at each point in space, i.e., the magnitude of the scattering pattern of at least one DCS 106 does not change. This is because one or more propagation channels through at least one DCS 106 remain fixed even when coding is applied, and the only change is their overall phase (∠(α d ) is shifted by . As a result, by using the STDC 112 according to the present disclosure, at least one propagation path through at least one DCS 106 remains fixed up to the phase shift between multiple time slots 116, which facilitates channel estimation and signal combining at at least one receiver 104.

[0089] The basic phase shift configuration matrix φ of each of the at least one DCS 106 d , therefore, F d (φ d ) is encoded as α d In other words, the coding according to the present disclosure can be applied to any given scattering pattern F d (φ d ), and thus STDC112 offers more flexibility than conventional coding, as the code is based on a phase shift pattern φ that is updated throughout the coding. d and therefore the fluctuating scattering pattern F d (φ d ) is imposed, resulting in scattering patterns that vary across the coding time slot.

[0090] Using equation (1), the scattering pattern α d F d (φ d ), the propagation channel from a transmitter antenna of at least one transmitter 102, referred to as transmitter antenna n, to a receiver antenna of at least one receiver 104, referred to as receiver antenna m, via the DCSd 106 can be described as shown in equation (3):

number

[0091] STDC112 according to the present disclosure is α d Since only the base or fundamental channel h m,d,n It can be pointed out that this results in a scaling of α , which itself remains fixed for the T time slots 116. d F d (φ d ) in equation (3), m,d,n 1 illustrates a propagation channel 114 from at least one transmitter 102 to at least one receiver 104 via at least one DCS 106, given by:

[0092] In the exemplary embodiment of FIG. i ∈{t1,t2,…,t T Each time slot 116t i , the transmitter antenna n of the at least one transmitter 102 is further configured to transmit information symbols x in a coded radio frequency signal, the coded radio frequency signal including a transformation of the information symbols x based on the STDC matrix B.

[0093] The transformation of the information symbol x is generally given by f TX (x,B,t i ), and the entries of each ith row of the STDC matrix B are {±β1,±β2,…,±β δ , 0}, time slot 116t i contains the information symbol x in, or the entry of each ith row of the STDC matrix B is

number

[0094] An information symbol x transmitted by transmitter antenna n of at least one transmitter 102 only needs to be known by at least one transmitter 102, and not by at least one DCS 106; thus, the wireless communication system 100 may reduce overhead requirements. This is in contrast to the prior art, where information symbols need to be known by at least one DCS 106.

[0095] Each of the at least one transmitter 102 may include a single transmitter antenna. Alternatively, each of the at least one transmitter 102 may include multiple transmitter antennas, and each transmitter antenna may be configured to transmit a different information symbol during the T time slots based on STDC 112. In other words, if the at least one transmitter 102 includes multiple transmitter antennas, transmission from each transmitter antenna may be performed independently at each transmitter antenna, and thus each transmitter antenna may be configured to transmit an independent information symbol x over the T time slots 116 by encoding its corresponding information symbol x using STDC 112, as disclosed above.

[0096] In this manner, STDC 112 according to the present disclosure can be a code for multiple independent single-antenna transmitters or multiple independent multi-antenna transmitters, and can also be applied to coding by only a single transmitter with multiple antennas or only a single transmitter with only a single antenna. The latter is a desirable feature in communication systems with low-complexity devices, such as IoT devices, that may not be able to implement STBC because it requires coding across at least two transmitter antennas. In other words, STDC 112 may enable exploiting space-time diversity by coding one or more propagation channels via one or more DCSs instead of coding symbols across multiple transmitter antennas.

[0097] 4, the transmitted symbol x can be obtained from any variable amplitude constellation, e.g., QAM with any number of constellation points (e.g., 4-QAM, 8-QAM, 16-QAM), or from a PSK constellation, even when the DCS element provides only phase shift control. In contrast, in traditional Alamouti designs with DCS, the symbols must be of constant amplitude and are therefore limited to PSK constellations (e.g., 4-PSK, 8-PSK, 16-PSK), which have worse performance than QAM constellations when the DCS element provides only phase shift control.

[0098] 4, the at least one transmitter 102 and the at least one DCS 106 are synchronized. The synchronization of the at least one transmitter 102 and the at least one DCS 106 can be achieved, for example, by using GPS signals. In 5G, GPS-based synchronization is used to synchronize evolved Node Bs (eNBs).

[0099] In the exemplary embodiment of FIG. 4, the at least one receiver 104 is configured to estimate 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 and / or one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver 104.

[0100] Scattering pattern α d F d (φ d ) one or more propagation channels g via at least one DCS d106 m,d,nis given by equation (3). The one or more direct propagation channels h0 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 through the at least one DCS 106. As disclosed above, the one or more propagation channels 114 may not include one or more direct propagation channels between the at least one transmitter 102 and the at least one receiver 104, for example, if the direct propagation channels are blocked and, as a result, the one or more direct propagation channels cannot be estimated by the at least one receiver 104.

[0101] In addition to the multiple time slots 116, additional time slots for training, or training time slots, may also be used for transmitting training pilots p from the at least one transmitter 102 to the at least one receiver 104 for channel estimation at the at least one receiver 104.

[0102] Then, t i ∈{t1,t2,…,t T Each time slot 116t i For , the at least one receiver 104 is further configured to determine information symbols x transmitted by the at least one transmitter 102 based on the STDC 112, based on the received coded radio frequency signal, and based on the estimated one or more propagation channels and / or the estimated one or more direct propagation channels via the at least one DCS 106.

[0103] That is, upon estimating the at least one propagation channel 114, the at least one receiver 104 can proceed to decode the received STDC-encoded signal transmitted by transmitter antenna n of the at least one transmitter 110 to obtain an estimate of each information symbol x transmitted by transmitter antenna n of the at least one transmitter 102 or by each transmit antenna.

[0104] Each of the at least one receiver 104 may include a single receiver antenna. Alternatively, one or more of the at least one receiver 104 may include multiple receiver antennas, each configured to receive the encoded radio frequency signals transmitted by the at least one transmitter 102 during multiple time slots 116.

[0105] The estimation of the information symbol x by the at least one receiver 104 may be based on the coded radio frequency signals received by at least one receiver antenna of the at least one receiver 104 during a total number T of time slots 116, one or more estimated propagation channels via the at least one DCS 106 and / or an estimated direct propagation channel, and diversity combining using the STDC matrix B. The diversity combining may be based on known combining procedures designed for STBC communications. In the case of multiple receiver antennas, the diversity combining may be applied separately to each coded radio frequency signal received by each receiver antenna. Furthermore, if the multiple receiver antennas are collocated or share a signal processing unit, the signals obtained from the multiple receiver antennas may be further combined, for example, in a maximal ratio combining (MRC) manner. As a result, the STDC 112 according to the present disclosure used in conjunction with diversity combining enables the use of 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 in the at least one receiver 104.

[0106] In this exemplary embodiment, controller 110 is configured to determine the STDC matrix B.

[0107] Because the coded radio frequency signals generated by the at least one transmitter 102 are based on the STDC matrix B, this matrix may need to be known by the at least one transmitter 102. The STDC matrix B may also need to be known at the at least one receiver 104 to decode the received coded radio frequency signals. Furthermore, the STDC matrix B, additionally or alternatively, may need to be known at the at least one receiver 104 to decode the received coded radio frequency signals. d may need to be known by at least one DCS 106. Therefore, 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, the at least one receiver 104, and the at least one DCS 106. While this introduces some overhead, the overhead is small because the STDC matrix B has only T×D elements.

[0108] Additionally or alternatively, because each of the at least one DCS 106 only needs its corresponding code, the controller may signal each of the at least one DCS 106 to generate a respective d-th column B of the STDC matrix B instead of the complete STDC matrix B. d , and a total number T of timeslots 116. As a result, further overhead reduction is achieved.

[0109] 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 dth column of the STDC matrix B, by signaling to the at least one transmitter 102, the at least one receiver 104, and the at least one DCS 106 before the at least one transmitter 102 transmits the coded radio frequency signal to the at least one receiver 104 during the multiple time slots 116.

[0110] In this manner, overhead may be further reduced and the efficiency of the wireless communication system 100 may be increased.

[0111] Alternatively, the controller 110, the at least one transmitter 102, the at least one receiver 104, and additionally or alternatively the at least one DCS 106 may be configured to store one or more tables including one or more STDC matrices B. The controller 110 may then be configured to send a code identifier by signaling the at least one transmitter 102, the at least one receiver 104, and the at least one DCS 106. The code identifier may include information specifying which of the one or more STDC matrices B in the table is to be used to generate the coded radio frequency signals transmitted from the at least one transmitter 102 to the at least one receiver 104 during the multiple time slots 116, to control the set of scattering elements 108 of the at least one DCS 106 during the multiple time slots 116, and to decode the coded radio frequency signals obtained by the at least one receiver 104 during the multiple time slots 116. The indication information may be embodied, for example, by an index that may specify which of the one or more STDC matrices B in the table is to be used. As a result, the overhead for communicating the STDC matrix B can be further reduced.

[0112] 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, the at least one receiver 104, and the at least one DCS 106. Additionally or alternatively, the at least one transmitter 102 may be configured to send each d-th column of the STDC matrix B instead of the complete STDC matrix B and the total number T of the plurality of time slots 116 by signaling to each of the at least one DCS d 106.

[0113] The at least one transmitter 102 may be further configured to determine the STDC matrix B offline. The at least one transmitter 102 may then be configured to send the STDC matrix B, additionally or alternatively the dth column of the STDC matrix B, by signaling to the controller 110, the at least one receiver 104, and the at least one DCS 106 before the at least one transmitter 102 transmits the encoded radio frequency signals to the at least one receiver 104 during the multiple time slots 116.

[0114] The controller 110, the at least one transmitter 102, the at least one receiver 104, and additionally or alternatively the at least one DCS 106 may each be configured to store one or more tables including one or more STDC matrices B. The at least one transmitter 102 may then be configured to send a code identifier by signaling to the controller 110, the at least one receiver 104, and the at least one DCS 106. The code identifier may include information specifying which STDC matrix B of the one or more STDC matrices B in the table is to be used. The indication information may be embodied, for example, by an index that may specify which STDC matrix B of the one or more STDC matrices B in the table is to be used.

[0115] 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, the at least one transmitter 102, the at least one receiver 104, or additionally or alternatively to another DCSd 106 of the at least one DCS 106. Additionally or alternatively, the at least one DCS 106 may be configured to send each d-th column of the STDC matrix B instead of the complete STDC matrix B and the total number T of the plurality of time slots 116 by signaling to another DCSd 106 of the at least one DCS 106.

[0116] Further, the at least one DCS 106 may be configured to determine the STDC matrix B offline. The at least one DCS 106 may then be configured to send the STDC matrix B, additionally or alternatively the dth column of the STDC matrix B, by signaling to the controller 110, the at least one transmitter 102, the at least one receiver 104, and other DCSs 106 of the at least one DCS 106 before the at least one transmitter 102 transmits the coded radio frequency signals to the at least one receiver 104 during the plurality of time slots 116.

[0117] The controller 110, the at least one transmitter 102, the at least one receiver 104, and additionally or alternatively the at least one DCS 106 may each be configured to store one or more tables including one or more STDC matrices B. The at least one DCS 106 may then be configured to send a code identifier by signaling to the other DCSs 106 of the controller 110, the at least one transmitter 102, the at least one receiver 104, and the at least one DCS 106. The code identifier may include information specifying which STDC matrix B of the one or more STDC matrices B in the table is to be used. The indication information may be embodied, for example, by an index that may specify which STDC matrix B of the one or more STDC matrices B in the table is to be used.

[0118] 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, the at least one transmitter 102, and the at least one DCS 106. Additionally or alternatively, the at least one receiver 104 may be configured to send each d-th column of the STDC matrix B and the total number T of the plurality of time slots 116 instead of the complete STDC matrix B by signaling to the at least one DCS 106.

[0119] The at least one receiver 104 may be configured to determine the STDC matrix B offline. The at least one receiver 104 may then be configured to send the STDC matrix B, and additionally or alternatively the dth column of the STDC matrix B, by signaling to the controller 110, the at least one transmitter 102, and the at least one DCS 106 before the at least one transmitter 102 transmits the encoded radio frequency signals to the at least one receiver 104 during the multiple time slots 116.

[0120] 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 including one or more STDC matrices B. The at least one receiver 104 may then be configured to send a code identifier by signaling to the controller 110, the at least one transmitter 102, and the at least one DCS 106. The code identifier may include information specifying which STDC matrix B of the one or more STDC matrices B in the table is to be used. The indication information may be embodied, for example, by an index that may specify which STDC matrix B of the one or more STDC matrices B in the table is to be used.

[0121] The STDC 112 according to the present disclosure may be applied, for example, to scale the DCS scattering pattern by a complex scalar. d The scattering pattern F of the DCS d of at least one DCS 106 having scattering elements 108 d (φ d ) is given as provided in Eq. (4).

number

number

[0122] complex scalar

number

number

number

number

number

[0123] As can be seen from equation (7) above, the new scattering pattern is determined by the α d Scattering pattern F scaled by d (φ d )

[0124] In another example, STDC 112 may be applied to scale the DCS scattering pattern by the conjugate of a complex scalar.

number

number

number

[0125] Using the new phase as described in equation (8) and the new scaling as defined above in equation (6), the resulting new scattering pattern is given by equation (9).

number

[0126] In a further example, STDC 112 may be applied to scale the DCS scattering pattern by the negative conjugate of a complex scalar.

number

number

number

[0127] Using the new phase as described in equation (10) above and the new scaling as defined in equation (6), the new resulting scattering pattern is given by equation (11).

number

[0128] The above examples of DCS pattern scaling consider scaling by a complex scalar, thus changing the scattering amplitude and phase of the scattering unit elements 108 of at least one DCS 106. However, it is difficult to have at least one DCS 106 scattering element 108 with controllable scattering amplitude, and therefore most known DCS configurations are for DCSs that only provide scattering phase control. If only the scattering phase of the at least one DCS 106 scattering element 108 can be controlled, γ d Simply set it to =1 and the procedure will be applied as described in the example above.

[0129] Figure 6 shows a schematic diagram of an example wireless communications system 100 based on the exemplary embodiment shown in Figure 4. Like elements are labeled with like reference numerals. In this example, the wireless communications system 100 may include a controller 110, a transmitter 102 having a transmitter antenna, a receiver having a receiver antenna 104, and two DCSs 106-1, 106-2. Each DCS 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may include a set of scattering elements 108-1, 108-2.

[0130] The controller 110 may be configured to determine the STDC 112, i.e., the controller 110 may be configured to determine the STDC matrix B. In this example, the total number of DCSs is D=2, and T max = 2 and δ = 2, which satisfies the requirement that δ ≦ D. δ=2}, T≦T max A well-known STBC matrix that maps to a T×D matrix B such that B is the 2×2 Alamouti STBC matrix given in equation (12).

number

[0131] This matrix B has entries in a given row of either {±β1,±β2,0} or

number

number

[0132] The controller 110 may then be configured to select the Alamouti matrix B in equation (12) as the STDC matrix B.

[0133] Additionally, 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 the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2. Alternatively, instead of the complete STDC matrix B, the controller 110 may send the respective dth column of the STDC matrix B by signaling each of the DCSs 106-1, 106-2.

[0134] The controller 110 may be configured to determine the STDC matrix B offline and may send the STDC matrix B, or additionally or alternatively the dth column of the STDC matrix B, by signaling the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2 before the transmitter 102 transmits the coded radio frequency signals to the receiver 104 during the multiple time slots 116.

[0135] Alternatively, the controller 110, the transmitter 102, the receiver 104, and additionally or alternatively, the DCSs 106-1 and 106-2 may be configured to store one or more tables including one or more STDC matrices B. The controller 110 may then be configured to send a code identifier by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1 and 106-2. The code identifier may include information specifying which STDC matrix B of the one or more STDC matrices B in the table to use. The indication information may be embodied, for example, by an index that may specify which STDC matrix B of the one or more STDC matrices B in the table to use.

[0136] The controller 110 may be further configured to determine basic phase-shift configuration matrices φ, φ for each DCS 106-1, 106-2, respectively. The basic phase-shift configuration matrices φ, φ may be obtained by the controller 110 in any or random manner, from a predetermined list, or using any available prior knowledge about the DCSs 106-1, 106-2.

[0137] The controller 110 may then control the sets of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 during the T=2 time slots 116 based on the STDC 112. That is, each time slot 116t of the T=2 time slots i For ∈{t1, t2}, the controller 110 calculates α d =B i,d B is i,d F d (φ d )=α d F d (φ d ) by setting the scattering pattern equal to B i,d is the entry in the ith row and dth column of the matrix B as disclosed above, and F d (φ d ) can be configured to be the scattering pattern of each DCSd 106-1, 106-2.

[0138] Alternatively, the controller 110 may d and control each DCS 106-1, 106-2 to determine the respective coding configuration.

[0139] For the STDC matrix B defined in equation (12), for time slot t1, the code of DCSd=1 106-1 is determined by the first entry of the respective code B1, i.e., the entry in the first row and the first column of the STDC matrix B provided in equation (12) sets α1=β1, and therefore, the controller 110 sets the coding configuration of DCSd=1 106-1 to B1F1(φ1), which is equal to B1F1(φ1).1,1 In time slot t1, the code of DCSd=2 106-2 is determined by the first entry of each code B2, and the controller 110 determines the coding configuration of DCSd=2 106-2 as B2F2(φ2), which is equal to B2F2(φ2). 1,2 F2(φ2), where β2 is the first entry of each code B2, i.e., the entry in the first row and second column of the STDC matrix B in equation (12) sets α2=β2.

[0140] Furthermore, for time slot t2, the sign of DCSd=1 106-1 is determined by the second entry of B1, and the entry in the second row and first column of the STDC matrix B in equation (12) is

number

number

number

number

[0141] [Table 1]

[0142] In this example with a single transmitter 101 and a single receiver 104 each having a single antenna, so that n=1 and m=1, the one or more propagation channels through the two DCSs 106-1, 106-2 are given by h1=h 1,1,1 and h2=h 1,2,1 These are defined as equations (13) and (14) based on equation (1).

number

[0143] α d F d (φ d ), the resulting propagation channel from at least one transmitter 102n=1 to at least one receiver 104m=1 through the DCSd is g 1,d,1 =α d h 1,d,1 Furthermore, for simplicity of notation, we use equation (3) which defines that g1 = g 1,1,1 =α1h 1,1,1 =α1h1 and g2=g 1,2,1 =α2h 1,2,1 =α2h2 is defined. The equations for the propagation channels through each DCS 106-1 and 106-2 are shown in Table 2.

[0144] [Table 2]

[0145] As can be seen from Table 2, α d The values ​​of are the δ≦D complex values ​​{β1,β2,…,β δ}, thus providing channel programming according to STDC 112 with controlled channel variations as shown in Table 2.

[0146] The controller 110 may then be configured to control the transmitter 102 to generate an encoded radio frequency signal based on the STDC 112. That is, for each time slot 116t i , the transmitter 102 may be configured to transmit information symbols x in a coded radio frequency signal, which is a signal obtained by transforming f of the information symbols x based on the STDC matrix B. TX (x,B,t i ) For time slot t1, the entries in the first row of matrix B given in equation (12) are {β1,β2∈±β1,±β2,0}, so transmitter 102 may be configured to send symbol x in time slot t1. For time slot t2, the entries in the second row of matrix B are

number

[0147] [Table 3]

[0148] 6, the transmitter 102 may be further configured to transmit a training pilot p during an additional time slot or training time slot based on the STDC 112. The training pilot p sent during the training time slot may be required by the receiver 104 to estimate one or more propagation channels 114 if estimates of one or more propagation channels via at least one DCS and / or one or more direct propagation channels are not already available at the receiver 104.

[0149] Table 4 shows the coded signals sent by transmitter 102, including additional time slots for transmission of training pilots p for channel estimation, and time slots t1 and t2 116 for transmission of coded signals (or transformations of information symbols) sent by transmitter 102. d The values ​​of α are also shown in Table 4. As explained above, during the two time slots 116t1, t2, α d depends on the STDC matrix B. During the additional time slots for training, the controller 110 may, for example, adjust α d The DCSs 106-1, 106-2 may be configured to control the sets of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 by setting the value of h. The resulting direct propagation channel between the transmitter 102 and the receiver 104, represented as h0, the propagation channels h1 and h2 through the two DCSs 106-1, 106-2, and the coded radio frequency signal received by the receiver 104 are also included in Table 4.

[0150] [Table 4]

[0151] The transmitted pilot p may be known at the receiver 104. Then, for each training time slot, the receiver 104 calculates the received training pilot p as well as the received signal

number

[0152] 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 coded radio frequency signal received during the time slot 116, and based on the estimated one or more propagation channels via at least one DCS 106, additionally or alternatively based on the estimated one or more direct propagation channels.

[0153] To do so, receiver 104 may proceed as follows: The received signal vector y is the signal received in the first time slot, i.e.

number

number

number

number

number

[0154] The composite matrix Q can then be calculated as in equation (18).

number

number

[0155] The diagonal terms in equation (19) indicate that the received signal combined using the combining matrix Q given in equation (18) provides diversity combining of the direct path between the transmitter 102 and the receiver 104 and the path between the transmitter 102 and the receiver 104 via DCSs 106-1 and 106-2. The diagonal terms contribute to the coherent combining contributions of the direct path and the path via DCSs 106-1 and 106-2.

[0156] Since the STDC matrix B and its complex values ​​β1 and β2 may be known at the receiver 104, the receiver 104 may be configured to construct the normalization matrix as in equation (20).

number

[0157] Using the received signal vector y, the synthesis matrix Q, and the normalization matrix N, the receiver 104 generates three initial estimates of the information symbols x transmitted by the transmitter 102 in the coded radio frequency signal, given by equation (21):

number

number

number

number

[0158] The noise term zx depends on both the information symbol x and the scaling term z. Since the propagation channels h0, h1, and h2 can be independent and random, their combination as in equation (23) for z is z~N(0,ν z ), where N(0,ν z ) has zero mean and variance v z is a Gaussian distribution with

[0159] When the direct propagation channel h0 is much weaker than the propagation channel via DCS 106-1, 106-2, which is conventionally considered in DCS and can be evaluated after channel estimation, the receiver 104 does not need to take into account the term proportional to h0, and the composite matrix Q is simplified as shown in equation (24).

number

number

number

number

number

[0160] In this case, h0 is weak, and h0 or its conjugate

number

[0161] Optionally, additive white Gaussian noise (AWGN), which is always present in received signals, may be added to the received signal vector in equation (15) to estimate the information symbol x. As a result, the process for combining initial estimates to obtain a final estimate of x, combining by Q and normalizing by N as disclosed above, also takes into account an additional noise term with a magnitude smaller than x.

[0162] In this example, as described above, β1 and β2 are considered to have general complex values. The values ​​of β1 and β2 may be assigned depending on the capabilities or characteristics of the at least one DCS 106-1, 106-2. For example, for a DCS that only provides control of the scattering phase shift, the values ​​of β1 and β2 may be unity. Given the specific values ​​of β1 and β2, further simplifications or modifications of the channel estimation and estimation of the information symbol x in the at least one receiver 104 can be implemented.

[0163] In a further example, at least one receiver 104 may include:

number

number

[0164] Figure 7 shows a schematic diagram of another example of a wireless communication system 100 based on the exemplary embodiment shown in Figure 4. Like elements are labeled with like reference numerals. In this example, the wireless communication system 100 may include a controller 110, one transmitter 102 having one transmitter antenna, one receiver 104 having one receiver antenna, and a single DCS 106. The DCS 106 may include a scattering surface 107, which may include a set of scattering elements 108.

[0165] 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 DCSs is D=1, and T max = 2 and δ = 2, which satisfies the requirement of δ ≦ D. The STDC matrix B is based on the Alamouti STBC matrix in equation (12) with values ​​β = β = 1, and the second column can be ignored, and is given by equation (30).

number

[0166] The controller 110 may then 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, the receiver 104, and the DCS.

[0167] 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, the receiver 104, and the DCS 106 before the transmitter 102 transmits the coded radio frequency signal to the receiver 104 during the multiple time slots 116.

[0168] Alternatively, the controller 110, the transmitter 102, the receiver 104, and additionally or alternatively, the DCS 106 may be configured to store one or more tables including one or more STDC matrices B. The controller 110 may then be configured to send a code identifier by signaling to the transmitter 102, the receiver 104, and the DCS 106. The code identifier may include information specifying which STDC matrix B in Equation (30) among one or more potential STDC matrices B stored in the lookup table is to be used. The indication information may be embodied, for example, by an index that may specify that the STDC matrix B in Equation (30) among one or more STDC matrices B in the table is to be used.

[0169] The controller 110 may generate the basic phase shift configuration matrix φ of the DCS 106, for example, in an arbitrary or random manner, or from a predetermined list, or using any available prior knowledge of the DCS 106 or a priori information about the propagation channel. d The system may be further configured to determine:

[0170] The controller 110 may then control the set of scattering elements 108 of the DCSd=1 106 during the T=2 time slots 116 based on the STDC 112. That is, each time slot 116t of the T=2 time slots i For ∈{t1, t2}, the controller 110 calculates α d =B i,d B is i,d F d (φ d )=α d F d (φ d ) to determine the coding configuration for DCSd=1, and B i,d is the entry in the i-th row and d-th column of matrix B, and F d (φ d ) can be configured to be the scattering pattern of DCSd106.

[0171] The first (and only) column of matrix B in equation (30) is

number

number

[0172] The controller 110 may then be configured to control the transmitter 102 to generate coded radio frequency signals during multiple time slots 116 based on the STDC matrix B. That is, for each time slot 116 t1, t2, the transmitter 102 transmits an information symbol x in a coded radio frequency signal, which is a signal obtained by transforming f of the information symbol x based on the STDC matrix B. TX (x,B,t i ) may be included.

[0173] For the STDC matrix B specified in equation (30), the transmitter 102 may be configured to send information symbol x in time slot 116t1 because the entries in the first row of STDC matrix B are {β1∈±β1,±β2,0}, and the transmitter 102 may be configured to send information symbol x in time slot 116t1 because the entries in the second row of STDC matrix B are

number

[0174] The resulting one or more direct propagation channels and one or more propagation channels via DCS 106 between transmitter 102 and receiver 104, as well as the transmitted and received signals for each time slot 116, are shown in Table 6.

[0175] [Table 6]

[0176] The transmitter 102 may use an additional time slot to send a pilot symbol p. The transmitted pilot may be known at the receiver 104. The receiver 104 may then calculate the received signal

number

[0177] The conjugated received signal vector y of the signal received by receiver 104 after the second time slot t2 is given by equation (31).

number

number

number

number

number

number

number

[0178] Optionally, AWGN can be added to the received signal vector in equation (31), which includes an additional noise term in the above equation.

[0179] FIG. 8a) shows a schematic diagram of another example of a wireless communications system 100 based on the exemplary embodiment shown in FIG. 4. Like elements are labeled with like reference numerals. In this example, the wireless communications system 100 may include a controller 110, two transmitters 102-1, 102-2, two transmitter antennas (i.e., n=1,2, and each transmitter has a single transmitter antenna), one receiver 104 with a single receiver antenna (i.e., m=1), and two DCSs d=1,2 106-1, 106-2. Each DCS 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may include a set of scattering elements 108-1, 108-2.

[0180] 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 T max= 2 and δ = 2, which satisfies the requirement of δ≦D. The STDC matrix B may be selected as the Alamouti STBC matrix given in equation (12) above.

[0181] The controller 110 may then 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, the receiver 104, and the DCSs 106-1, 106-2. Additionally or alternatively, the controller 110 may send the respective dth column of the STDC matrix B and the total number T of the plurality of time slots 116 by signaling to each DCS 106-1, 106-2.

[0182] The controller 110 may be configured to determine the STDC matrix B offline and may send the STDC matrix B, or additionally or alternatively the dth column of the STDC matrix B, by signaling the transmitters 102-1, 102-2, the receiver 104, and the DCSs 106-1, 106-2 before each transmitter 102-1, 102-2 transmits an encoded radio frequency signal to the receiver 104 during the multiple time slots 116.

[0183] Alternatively, the controller 110, the transmitters 102-1, 102-2, the receiver 104, and additionally or alternatively, the DCSs 106-1, 106-2 may be configured to store one or more tables including one or more STDC matrices B. The controller 110 may then be configured to send a code identifier by signaling to the transmitters 102-1, 102-2, the receiver 104, and the DCSs 106-1, 106-2. The code identifier may include information specifying which STDC matrix B provided in Equation (12) among the one or more STDC matrices B stored in the look-up table to use. The indication information may be embodied, for example, by an index that may specify which STDC matrix B provided in Equation (12) among the one or more STDC matrices B in the table to use.

[0184] The controller 110 may generate a basic phase shift configuration matrix φ for each DCS 102-1, 102-2, for example in an arbitrary or random manner, or from a predetermined list, or using any available prior knowledge of the DCSs 106-1, 106-2. d The system may be further configured to determine:

[0185] The controller 110 may then control the sets of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 during the T=2 time slots 116 based on the STDC 112, as disclosed above in the example of Figure 6. The details will not be repeated again.

[0186] The coding structure of each DCS 106-1, 106-2 is independent of the number of transmitters 102-1, 102-2 and transmitter antennas, and is independent of the information symbols sent by the transmitters 102-1, 102-2. The coding structure of each time slot 116 and each DCS 106-1, 106-2 is the same as in the example of Figure 6 and is shown in Table 1 above.

[0187] In this example, there are two single-antenna transmitters 102-1, 102-2 and two DCSs 106-1, 106-2, so there may be a total of four propagation channels through DCSs 106-1, 106-2 given by equations (36)-(43).

number

number

[0188] For each time slot 116, one or more propagation channels from transmitters 102-1, 102-2 via DCSs 102-1, 102-2 are shown in Table 7.

[0189] [Table 7]

[0190] As can be seen from Table 7, the propagation channels g1, g2, g3, g4 vary depending on the value of the STDC matrix B given in equation (12), thus providing channel programming according to STDC 112.

[0191] The controller 110 may then be configured to control each transmitter 102-1, 102-2 to generate an encoded radio frequency signal during a plurality of time slots 116 based on the STDC 112. That is, each time slot 116t i , each transmitter 102-1, 102-2 transmits an information symbol x in a coded radio frequency signal, and the coded radio frequency signal is TX (x,B,t i ) may include a transformation of the information symbols x based on the STDC matrix B.

[0192] The information symbols transmitted from each transmitter 102-1, 102-2 are x n where n=1, 2. The two symbols x1 and x2 can be completely independent. Each transmitter 102-1, 102-2 transmits the same information symbol x in the coded radio frequency signal during two time slots 116t1 and t2. n may be transmitted.

[0193] Using the STDC matrix B specified in equation (12), during time slot t1, transmitter antenna n of transmitter 102-n receives the symbol x n During time slot t, transmitter antenna n of transmitter 102-n may be configured to transmit

number

number

[0194] [Table 8]

[0195] In the example of FIG. 8a), transmitters 102-1, 102-2 may be further configured to transmit training pilots p during additional time slots or training time slots based on STDC 112. If estimates of one or more propagation channels via at least one DCS and / or one or more direct propagation channels are not already available at receiver 104, said training pilots p transmitted during training time slots may be required by receiver 104 to estimate one or more propagation channels 114.

[0196] Table 9 shows the coded radio frequency signals transmitted by transmitters 102-1, 102-2 for two time slots 116t1, t2, including an additional time slot for transmission of training pilot p. d The values ​​of α are also shown in Table 9. During the two time slots t1 and t2, dThe value of depends on the STDC matrix B. During the training time slots, the controller 110 may, for example, adjust α d h may be configured to control the sets of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 by setting the value of 0,1 , h 0,2 The resulting direct propagation channels between the transmitters 102-1, 102-2 and the receiver 104, denoted as , and the propagation channels through the two DCSs 106-1, 106-2, are also shown in Table 9.

[0197] [Table 9]

[0198] The transmitted pilot p may be known at the receiver 104. Then, for each training time slot, the receiver 104 calculates the received training pilot p as well as the received signal

number

[0199] Furthermore, for each time slot 116t1, t2, the receiver 104 determines an information symbol x transmitted by one of the transmitters 102-1, 102-2 based on the received coded radio frequency signal and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, additionally or alternatively based on the estimated one or more direct propagation channels, based on the STDC 112. nThe method may be configured to determine:

[0200] To do so, receiver 104 may proceed as follows: The received signal vector y is the signal received in the first time slot, i.e.

number

number

number

number

number

number

[0201] The composite matrix Q and the normalization matrix N can be calculated as shown in equations (47) and (48), respectively. Q=H * (47)

number

number

number

number

number

number

number

number

[0202] Propagation channel h 0,1 , h 0,2 , h1, h2, h3, and h4 are independent random variables, so the resulting noise terms z1 and z2 in equations (50) and (51) are Gaussian random variables with zero-mean distribution.

number

[0203] Adaptation to multiple antenna transmitters is straightforward by following the example of FIG. 8a) with two transmitters, as shown in FIG. 8b). FIG. 8b) shows an example of a wireless communication system 100 based on the exemplary embodiment shown in FIG. 4, but with a single transmitter 102 with two transmitter antennas. Like elements are given like reference numerals. Following the example of FIG. 8a), the same propagation channels as in Table 7 are obtained, the same transmitted symbols per antenna as in Tables 8 and 9 are obtained, and the same received signals as in Table 9 are obtained. The signal processing at the receiver 104 is the same as described with respect to equations (44) through (51).

[0204] Extension to more than two transmitters is straightforward following the examples of Figure 8a) with two transmitters 102-1, 102-2 and Figure 8b) with a multiple antenna transmitter. Figure 9 shows a schematic diagram of a further example of a wireless communication system 100 based on the exemplary embodiment shown in Figure 4. Like elements are labeled with like reference numerals. In this example, the wireless communication system 100 may comprise a 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 184-1, 108-2, 108-3.

[0205] 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 T max = 4 and δ = 3, which satisfies the requirement of δ ≦ D. δ=3}, T≦T max The STBC matrix that maps to the T×D matrix B such that

number

[0206] The matrix B given by equation (52) has entries in a given row of either {±β1,±β2,±β3,0} or

number

[0207] Additionally, the controller 110 may be configured to send, by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, and 106-3, the total number T of the plurality of time slots 116 and the STDC matrix B. Alternatively, instead of the complete STDC matrix B, the controller 110 may send, by signaling to each DCS 106-1, 106-2, and 106-3, the respective dth column of the STDC matrix B and the total number T of the plurality of time slots 116.

[0208] 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 dth column of the STDC matrix B, by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, and 106-3 before the transmitter 102 transmits the coded radio frequency signals to the receiver 104 during the multiple time slots 116.

[0209] Alternatively, the controller 110, the transmitter 102, the receiver 104, and additionally or alternatively, the DCSs 106-1, 106-2, and 106-3 may be configured to store one or more tables including one or more STDC matrices B. The controller 110 may then be configured to send a code identifier by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, and 106-3. The code identifier may include information specifying which STDC matrix B in Equation (52) to use among the one or more STDC matrices B stored in the look-up table. The indication information may be implemented, for example, by an index that may specify which STDC matrix B in Equation (52) to use among the one or more STDC matrices B in the table.

[0210] The controller 110 may be further configured to determine basic phase-shift configuration matrices φ, φ, φ for each DCS 106-1, 106-2, 106-3. The basic phase-shift configuration matrices φ, φ, φ may be obtained by the controller 110 in any or random manner, from a predetermined list, or using any available prior knowledge of the DCSs 106-1, 106-2, 106-3.

[0211] The controller 110 may then control the sets of scattering elements 108-1, 108-2, 108-3 of the DCSs 106-1, 106-2, 106-3 during T=4 time slots 116 based on the STDC 112. That is, for each time slot 116t i For ∈{t1, t2, t3, t4}, the controller 110 calculates α d =Bi,d B is i,d F d (φ d )=α d F d (φ d ) by setting the scattering pattern equal to B i,d is the entry in the ith row and dth column of the matrix B as disclosed above, and F d (φ d ) can be configured to be the scattering pattern of each DCSd 106-1, 106-2, 106-3.

[0212] The resulting coding configuration for each time slot 116 and each DCS 106-1, 106-2, 106-3 is shown in Table 10.

[0213] [Table 10]

[0214] A scattering pattern equal to zero (0) can be obtained by using a DCS surface whose scattering properties can be turned off, or by using a particular DCS configuration such that the energy scattered by the scattering elements is minimized (this is known, for example, in the radar context as minimizing the radar cross section).

[0215] In this example with a single-antenna transmitter 102 and a single-antenna receiver 104, therefore n=1 and m=1, h1=h 1,1,1 , h2=h 1,2,1 , and h3=h 1,3,1 The one or more propagation channels through the DCSs 106-1, 106-2, and 106-3, expressed as: are given by equations (53) to (55) based on equation (1).

number

[0216] α dF d (φ d ), the resulting propagation channel through DCSd from transmitter antenna n=1 to receiver antenna m=1 is g 1,d,1 =α d h 1,d,1 Furthermore, for simplicity of notation, we use equation (3) which defines that g1 = g 1,1,1 =α1h 1,1,1 =α1h1, g2=g 1,2,1 =α2h 1,2,1 = α2h2, and g3=g 1,3,1 =α3h 1,3,1 =α3h3 is defined. The propagation channels through each of DCS 106-1, 106-2, and 106-3 are shown in Table 11.

[0217] [Table 11]

[0218] The controller 110 may be configured to control the transmitter 102 to generate an encoded radio frequency signal based on the STDC 112. That is, for each time slot 116t i For f, the transmitter 102 may be configured to transmit information symbols x in an encoded radio frequency signal. TX (x,B,t i ) given by equation (52).

[0219] Time slot t i For B, the transmitter 102 may be configured to send symbol x if the entry in the i-th row of STDC matrix B belongs to {±β1,±β2,±β3,0}; otherwise, the entry in the i-th row of STDC matrix B belongs to

number

[0220] [Table 12]

[0221] 9, the transmitter 102 may be further configured to transmit training pilots p during additional time slots or training time slots. If estimates of one or more propagation channels via at least one DCS and / or one or more direct propagation channels are not already available at the receiver 104, the training pilots p transmitted during the additional time slots or training time slots may be required by the receiver 104 to estimate one or more propagation channels 114.

[0222] Table 13 shows the coded signals transmitted by the transmitter 102, including the training time slots for transmission of training pilots p for channel estimation, and the signals transmitted during the four time slots 116 t1, t2, t3, and t4. d The values ​​of α are also shown in Table 13. As explained above, during the four time slots 116 t1, t2, t3, and t4, α d depends on the value of the STDC matrix B. During the training time slots 116, the controller 110 may, for example, adjust α in a predetermined manner based on the STDC matrix B. dThe DCSs 106-1, 106-2, 106-3 may be configured to control the sets of scattering elements 108-1, 108-2, 108-3 of the DCSs 106-1, 106-2, 106-3 by setting the value of . The resulting direct propagation channel between the transmitter 102 and receiver 104, the propagation channel through the DCSs 106-1, 106-2, 106-3, and the coded radio frequency signal received by the receiver 104 during each time slot 116 and training slot are also included in Table 13.

[0223] [Table 13]

[0224] The transmitted pilot p may be known at the receiver 104. Then, for each training time slot, the receiver 104 calculates the received training pilot p as well as the received signal

number

[0225] 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 coded radio frequency signal received during the time slot 116, and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, 106-3, additionally or alternatively based on the estimated one or more direct propagation channels.

[0226] To that end, receiver 104 may proceed as follows: Decoding the selected 4×3 STDC matrix B given in equation (52) yields the signal received in the first time slot of multiple time slots 116, i.e.,

number

number

number

[0227] Since one or more propagation channels h0, h1, and h2 have been estimated by the receiver 104, the overall channel matrix H can be constructed as in equation (57).

number

number

[0228] The composite matrix Q and the normalization matrix N can be easily calculated as shown in equations (59) and (60), respectively.

number

[0229] Four initial estimates of the transmitted symbols x are obtained using the received signal vector y in equation (58), the composite matrix Q in equation (59), and the normalization matrix N in equation (60).

number

number

[0230] Four initial guesses

number

number

[0231] The noise term zx depends on both the symbol x and the scaling term z. Because the channels h0, h1, h2, and h3 are independent and random, the resulting expression for z is z~N(0,ν z ), where N(0,ν z ) has zero mean and variance ν, which depends on the channel statistics and the resulting composition of terms in the term z. z is a Gaussian distribution with . Using more DCSs, the term z includes the addition of additional random terms, and therefore the variance of z decreases, and the value of z becomes much closer to a mean of zero, i.e., z is said to go to zero more quickly as the number of DCSs used increases. Using more DCSs requires the use of more time slots, but this can compensate for the additional required time slots because more than one independent transmitter may be included in wireless communication system 100 and may transmit simultaneously.

[0232] If the direct propagation channel h0 is weak, as is conventionally considered in DCS and can be evaluated after channel estimation, the receiver 104 does not need to take into account the term proportional to h0, and the composite matrix Q can be calculated as in equation (63).

number

number

[0233] The values ​​of β1, β2, and β3 in the STDC matrix B may be determined depending on the capabilities or characteristics of the DCSs 106-1, 106-2, and 106-3. For example, for a DCS that only provides control of the scattering phase shift, the values ​​of β1, β2, and β3 may be unity. Given the specific values ​​of β1, β2, and β3, further simplifications or alternative implementations of the channel estimation and estimation of the information symbols x in the at least one receiver 104 may be implemented.

[0234] Alternatively, four initial guesses for the transmitted symbol x

number

[0235] Optionally, AWGN may be added to the received signal vector of equation (58) to estimate the information symbol x. As a result, the process for combining by Q, normalizing by N, and combining the initial estimates to obtain the final estimate of x as disclosed above also takes into account an additional noise term with a magnitude smaller than x.

[0236] Figure 10 shows an example of signaling exchanged in the wireless communication system 100 of Figure 6. In particular, the example of Figure 10 illustrates a scenario in which the wireless communication system 100 may include a controller 110, one transmitter 102, one receiver 104, and two DCSs 106-1, 106-2. Each DCS 106-1, 106-2 may include a scattering surface 107-1, 107-2, and each scattering surface 107-1, 107-2 may include a set of scattering elements 108-1, 108-2. The transmitter 102 and DCSs 106-1, 106-2 may be synchronized.

[0237] The controller 110 may be configured to determine the STDC 112, i.e., the controller 110 may be configured to determine the STDC matrix B, for example, by following the flowchart disclosed above and shown in FIG. 5.

[0238] In this example, D=2, and as disclosed above for the example of FIG. 6, T max = 2 and δ = 2.

[0239] Further, the controller 110 may be configured to send the total number T=2 of the plurality of time slots 116 and the STDC matrix B by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2. Additionally, the controller 110 may determine training time slots for channel estimation and may send the training time slots by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2.

[0240] 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, the receiver 104, and the DCSs 106-1, 106-2 before the transmitter 102 transmits the coded radio frequency signals to the receiver 104 during the multiple time slots 116.

[0241] The controller 110 may be further configured to control the transmitter 102 to generate coded radio frequency signals during T=2 time slots 116 based on the STDC 112. That is, for each time slot 116t i For f, the transmitter 102 may be configured to transmit information symbols x in an encoded radio frequency signal. TX (x,B,t i ) The details regarding coding information symbols by the transmitter 102 are as disclosed above for the example of FIG. 6 and will not be repeated here again.

[0242] Furthermore, the controller 110 may control the sets of scattering elements 108-1, 108-2 of the DCSs 106-1, 106-2 during the T=2 time slots 116 based on the STDC 112. That is, each time slot 116t of the T=2 time slots i For ∈{t1, t2}, the controller 110 calculates α d =B i,d and d=1,2 B i,d F d (φ d )=α d F d (φ d ), and the coding configuration of each DCS 106-1, 106-2 can be determined by setting the scattering pattern equal to B i,d is the entry in the ith row and dth column of the STDC matrix B as disclosed above, and F d (φ d ) are the scattering patterns of each DCSd106-1 and 106-2.

[0243] Alternatively, the controller 110 may control each DCS 106-1, 106-2 to select the respective dth column of the STDC matrix B and further determine its coding configuration as mentioned above. Additionally or alternatively, the controller 110 may control each DCS 106-1, 106-2 to apply the determined coding configuration during multiple time slots 116.

[0244] The coding configuration of each DCS 106-1, 106-2 is the same as the example in Fig. 6. The details will not be repeated again.

[0245] Additionally, the transmitter 102 may be configured to transmit a training pilot p during a training time slot based on STDC 112 to the receiver 104, and the receiver may be configured to estimate one or more propagation channels.

[0246] Then, transmitter 102 sends symbol x in time slot t1 and symbol x in time slot t2. * may be configured to send

[0247] The controller 110 may then control the receiver 104 to receive, during a plurality of time slots 116, the coded radio frequency signals transmitted by the transmitters 102. The receiver 104 may then be configured to determine an information symbol x transmitted by at least one transmitter 102 based on the STDC 112, based on the received coded radio frequency signals, and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, additionally or alternatively, based on the estimated one or more direct propagation channels.

[0248] Figure 11 shows another example of signaling exchanged in the wireless communication system 100 of Figure 6. The example of Figure 11 is the same as the example of Figure 10, except that in Figure 11, the controller 110 may be further configured to determine basic phase shift configuration matrices φ1, φ2 for each DCS 106-1, 106-2. The controller 110 may then be configured to send the basic phase shift configuration matrices φ1, φ2 by signaling to each DCS 106-1, 106-2. Additionally, the controller 110 may be configured to send the respective dth column of STDC matrix B instead of the full matrix STDC matrix B by signaling to each DCS 106-1, 106-2.

[0249] The remaining signaling exchanged between the controller 110, the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, as well as their configurations, are the same as in the example of FIG. 10 and will not be repeated here.

[0250] Figure 12 shows an example of signaling exchanged in wireless communications system 100. The example of Figure 12 illustrates a scenario in which wireless communications system 100 may include a controller 110, one transmitter 102, one receiver 104, and D DCSs, exemplary DCSs 106-1, 106-2, and 106-D. Each DCS 106-1, 106-2, 106-D may include a scattering surface 107-1, 107-2, 107-D, and each scattering surface 107-1, 107-2, 107-D may include a set of scattering elements 108-1, 108-2, 108-D. The transmitter 102 and DCSs 104-1, 104-2, 104-D may be synchronized.

[0251] The controller 110 may be configured to determine the STDC 112, i.e., the controller 110 may be configured to determine the STDC matrix B, for example, by following the flowchart disclosed above and shown in FIG. 5.

[0252] 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 and the receiver 104 before the transmitter 102 transmits the encoded radio frequency signals to the receiver 104 during the multiple time slots 116.

[0253] Furthermore, the controller 110 calculates the basic phase shift configuration matrices φ1, φ2, ..., φ of each DCS 106-1, 106-2, 106-D. D The controller 110 may then be configured to determine f(φ d ,B d ) can be configured to send the respective information.

[0254] Information f(φ d ,B d ) for each time slot 116 t1, t2, ..., t T The basic phase shift configuration matrix φ d For example, the information f(φ) may include information for configuring each DCSd in some state and time that specifies d ,B d ) is the basic phase shift configuration matrix φ d and the respective codes of DCS106-1, 106-2, and 106-D, i.e., B d and each d-th column of the STDC matrix B, expressed as: d ,B d ) may include any other type of information that may facilitate achieving a desired configuration of each DCS 106-1, 106-2, 106-D.

[0255] The controller 110 receives the information f(φ d ,B d ) offline and then send it by signaling to the respective DCSs 106-1, 106-2, 106-D.

[0256] Alternatively, the controller 110 may calculate each piece of information f(φ d ,B d ) may be sent at once, or in each time slot 116 t1, t2, ..., t T That is, the controller 110 may send the information f(φ) by signaling when the configuration of each DCS 106-1, 106-2, 106-D needs to be updated. d ,B d ) to each of DCSs 106-1, 106-2, and 106-D.

[0257] 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 and the receiver 104. Additionally, the controller 110 may determine training time slots for channel estimation and may send the training time slots by signaling to the transmitter 102, the receiver 104, and the DCSs 106-1, 106-2, and 106-D.

[0258] The controller 110 may then be configured to control the set of scattering elements 108-1, 108-2, 108-D of the DCSs 106-1, 106-2, 106-D during multiple time slots 116 based on the STDC 112. That is, for each time slot 116t i ∈{t1,t2,…,t T}, the controller 110 calculates B i,d F d (φ d ) and the coding configuration of each 106-1, 106-2, 106-D can be determined by setting the scattering pattern equal to B i,d is the entry in the ith row and dth column of the STDC matrix B, and F d (φ d ) are the scattering patterns of each DCS 106-1, 106-2, and 106-D.

[0259] For example, in time slot t1, as shown in FIG. 12, the coding structure of DCSd=1 106-1 is B 1,1 F1(φ1), and the coding structure of DCSd=2 106-2 is B 1,2 In time slot t2, the coding structure of DCSd=1 106-1 is B 2,1 F1(φ1), and the coding structure of DCSd=2 106-2 is B 2,2 F2(φ2), and similarly, time slot t T The coding structure of DSCD106-D in B T,D F1(φ D ).

[0260] Alternatively, the controller 110 may control each DCS 106-1, 106-2, 106-D to determine its encoding configuration.

[0261] The controller 110 may then control the transmitter 102 to generate an encoded radio frequency signal based on the STDC 112. Furthermore, each time slot 116t i ∈{t1,t2,…,t T}, the transmitter 102 may be configured to transmit information symbols x in a coded radio frequency signal. The coded radio frequency signal is a coded radio frequency signal with f TX (x,B,t i ) may include a transformation of the information symbol x.

[0262] Conversion f TX (x,B,t i ) is the sum of the entries of each ith row of the STDC matrix B, where the entries are {±β1,±β2,…,±β δ , 0}, time slot 116t i or the entry of each i-th row of the STDC matrix B is

number

[0263] The transmitter 102 may then be configured to transmit the training pilot p during a training time slot 116 to the receiver 104, which may be configured to estimate one or more propagation channels.

[0264] The transmitter 102 transmits each time slot 116t i ∈{t1,t2,…,t T}, the transformation of information symbols fTX (x,B,t i ) may be further configured to transmit

[0265] The controller 110 may then control the receiver 104 to receive, during a plurality of time slots 116, the coded radio frequency signals transmitted by the transmitters 102. The receiver may then be configured to determine information symbols x transmitted by at least one transmitter 102 based on the STDC 112, based on the received coded radio frequency signals, and based on the estimated one or more propagation channels via the DCSs 106-1, 106-2, 106-D and / or the estimated one or more direct propagation channels.

[0266] The STDC 112 according to the present disclosure can be extended in a simple and flexible way to cases where multiple information symbols are transmitted per time slot. T} each time slot 116t i The duration of each of the time slots 116 can be adapted to span the duration of one information symbol, as shown schematically in Figure 13a), or to span the duration of multiple information symbols (sometimes represented as a frame), as shown schematically in Figure 13a. Figure 13a) illustrates an example of a time slot 116 in the wireless communication system 100 of Figure 6 for four information symbols 116, exemplary x1, x2, x3, and x4, being transmitted, each time slot 116 spanning the duration of one information symbol. Figure 13b) illustrates an example of a time slot 116 in the wireless communication system 100 of Figure 6 for four information symbols 116, exemplary x1, x2, x3, and x4, being transmitted, each time slot 116 spanning the duration of multiple information symbols or a frame duration.

[0267] 14 illustrates a wireless communication method 200 according to the present disclosure. The method 200 may be performed by the wireless communication system 100 of FIG. 4, as disclosed above.

[0268] The method 200 includes a step S202 of controlling, by the controller 110, at least one transmitter 102 to generate coded radio frequency signals during a plurality of time slots 116 based on a space-time DCS code STDC 112, the STDC 112 being a number that is greater than or equal to a total number of the at least one DCS 106 and a maximum number T of the plurality of time slots 116. max Depends on.

[0269] The method 200 further includes a step S204 of controlling, by the controller 110, the set of scattering elements 108 of the at least one DCS 106 during the plurality of time slots 116 based on the STDC 112. The at least one DCS 106 comprises a scattering surface 107 comprising a set of scattering elements 108, each scattering element 108 having a controllable phase shift.

[0270] Further, the method 200 includes a step S206 of transmitting, by the at least one transmitter 102, the encoded radio frequency signal to the at least one receiver 104 during a plurality of time slots 116.

[0271] The method 200 further includes a step S208 of receiving, by the at least one receiver 104, the encoded radio frequency signals transmitted by the at least one transmitter 102 during the plurality of time slots 116.

[0272] The coded radio frequency signals transmitted by the at least one transmitter 102 during the multiple time slots 116 propagate from the at least one transmitter 102 to the at least one receiver 104 via one or more propagation channels 114, which may include one or more propagation channels via the at least one DCS 106, and additionally or alternatively one or more direct propagation channels.

[0273] Method 200 may further include actions according to the above-described exemplary embodiment of wireless communication system 100. Thus, method 200 achieves the same advantages as wireless communication system 100 as disclosed above.

[0274] The present disclosure further provides a computer program product including program code for, when executed on a processor, performing the method 200 shown in Figure 14. The computer program may be included in a computer-readable medium of the computer program product. The computer-readable medium may essentially include any memory, such as a ROM (read-only memory), a PROM (programmable read-only memory), an EPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), or a hard disk drive.

[0275] The computer program product may further include actions according to the above-described method 200. Thus, the computer program product achieves the same advantages as the method 200 and the wireless communication system 100.

[0276] The present disclosure has been described with reference to various exemplary embodiments and implementations. However, other variations can be understood and effected by those skilled in the art in practicing the claimed subject matter, from a study of the drawings, the disclosure, and the independent claims. In the claims and the description, the word "comprises" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous embodiment. [Explanation of symbols]

[0277] 100 Wireless Communication System 101 Transmitter 102 Transmitter 102-1 Single Antenna Transmitter 102-2 Single Antenna Transmitter 104 Receiver, receiver antenna 106 DCS, scattering element 106-1 DCS 106-2 DCS 106-3 DCS 106-D DCS 107 Scattering surface 107-1 Scattering surface 107-2 Scattering surface 107-3 Scattering surface 107-D Scattering Surface 108 Scattering Elements, Scattering Unit Elements 108-1 Scattering Elements 108-2 Scattering Elements 108-3 Scattering Elements 108-D Scatter Element 110 Controller 112 STDC 114 Propagation Channel 116 time slots 200 Wireless Communication Methods

Claims

1. A wireless communication system (100), comprising: at least one transmitter (102) configured to transmit coded radio frequency signals to at least one receiver (104) during a plurality of time slots (116); at least one digitally controllable scatterer DCS, the DCS (106) comprising a scattering surface (107) comprising a set of scattering elements (108), each of the scattering elements having a controllable phase shift; A controller (110), controlling the at least one transmitter (102) to generate the coded radio frequency signal during the plurality of time slots (116) based on a space-time DCS code STDC (112); controlling the set of scattering elements (108) of the at least one DCS (106) during the plurality of time slots (116) based on the STDC (112); a controller (110) configured to: at least one receiver (104) configured to receive and acquire the coded radio frequency signals transmitted by the at least one transmitter (102) during the plurality of time slots (116); Equipped with the coded radio frequency signals transmitted by the at least one transmitter (102) during the plurality of time slots (116) propagate from the at least one transmitter (102) to the at least one receiver (104) via one or more propagation channels (114), the one or more propagation channels (114) including one or more propagation channels via the at least one DCS (106) and / or one or more direct propagation channels; The STDC (112) is a unit of the total number of the at least one DCS (106) and the maximum number T of the plurality of time slots (116). max Depends on, A wireless communication system (100).

2. The STDC (112) includes an STDC matrix B, the STDC matrix B having dimensions T×D, where D is the total number of the at least one DCS (106), D≧1, and T≦T max 2. The wireless communication system (100) of claim 1, wherein ≡ ...

3. The STDC (112) matrix B is a set of δ≦D complex values ​​{β 1 , β 2 , …, β δ }, and the entries of row i of the matrix B are defined based on {±β 1 , ±β 2 , …, ±β δ , 0} or [Equation 1] belong to one of the [Equation 2] is β for ∀l∈{1, ..., D} l is the complex conjugate of T max is T max 3. The wireless communication system (100) of claim 1 or 2, wherein:

4. The sign of each of the at least one DCS (106) d, where d∈{1, 2, ..., D}, is determined by a respective d-th column of the STDC matrix B, and the d-th column of the STDC matrix B is B d 4. The wireless communication system (100) of claim 1, wherein:

5. Time slot (116) i ∈{t 1 , t 2 , …, t T }, the controller (110) assigns the coding configuration of each of the at least one DCS (106) d, where d∈{1, 2, ..., D}, to B i，d F d (φ d ) and F d (φ d ) is the scattering pattern of the at least one DCS(106)d, and φ d is the basic phase shift configuration matrix of the at least one DCS (106) d, and B i，d are the respective symbols B d 5. The wireless communication system (100) of claim 1, configured such that:

6. t i ∈{t 1 , t 2 , …, t T } for each time slot (116) t i wherein the at least one transmitter (102) transmitting an information symbol x in said coded radio frequency signal; The encoded radio frequency signal includes a transformation of the information symbols x based on the STDC matrix B, the transformation of the information symbols x comprising: The entries of each i-th row of the STDC matrix B are {±β 1 , ±β 2 , …, ±β δ , 0}, the time slot (116) t i or The entries of each i-th row of the STDC matrix B are [Equation 3] If the time slot (116) t i Information symbol x in ＊ Including, x ＊ is the complex conjugate of the information symbol x, 6. The wireless communication system (100) of any one of claims 1 to 5, further configured to:

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

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

9. One of the controller (110), the at least one transmitter (102), the at least one receiver (104), or the at least one DCS (106) determining the STDC matrix B; signaling the total number T of the plurality of time slots (116) and the STDC matrix B to the controller (110) and / or the at least one transmitter (102) and / or the at least one receiver (104) and / or the at least one DCS (106), and / or signaling the respective d-th columns of the STDC matrix B and the total number T of the plurality of time slots (116) to the at least one DCS (106) d.

4. The wireless communication system (100) of claim 2 or 3, further configured to:

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

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

12. A wireless communication method (200), comprising: controlling, by a controller (110), at least one transmitter (102) to generate coded radio frequency signals during a plurality of time slots (116) based on a space-time DCS code STDC (112); controlling, by the controller (110), a set of scattering elements (108) of at least one DCS (106) during the plurality of time slots (116) based on the STDC (112), the at least one DCS (106) comprising a scattering surface (107) comprising the set of scattering elements (108), each of the scattering elements (108) having a controllable phase shift; transmitting, by the at least one transmitter (102), the encoded radio frequency signal to at least one receiver (104) during the plurality of time slots (116); receiving, by the at least one receiver (104), the encoded radio frequency signals transmitted by the at least one transmitter (102) during the plurality of time slots (116); Including, the coded radio frequency signals transmitted by the at least one transmitter (102) during the plurality of time slots (116) propagate from the at least one transmitter (102) to the at least one receiver (104) via one or more propagation channels (114), the one or more propagation channels (114) including one or more propagation channels via the at least one DCS (106) and / or one or more direct propagation channels; The STDC (112) is a unit of the total number of the at least one DCS (106) and the maximum number T of the plurality of time slots (116). max Depends on, A wireless communication method (200).

13. 13. A computer program product comprising program code for performing the wireless communication method (200) of claim 12 when executed on a processor.

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