Method and apparatus for equal energy codebook for coupled antennas with transmission lines

Abstract

The present invention relates to a method and apparatus for an equal energy codebook for coupled antennas with a transmission line. A method and apparatus provide an equal energy codebook for coupled antennas with a transmission line. Multiple precoders can be received from a codebook in a transmitter with an antenna array. Each of the multiple precoders can be transformed into a transform precoder so that the transmit power of each transform precoder is equal to the transmit power of each other transform precoder in the multiple precoders. The transmit power can be expressed as a quadratic form relative to the corresponding precoder. The quadratic form can be based on the transmission line impedance of the transmission line between the signal source and the antenna array. A receive signal can be received from a signal source. A transform precoder in the multiple transform precoders can be applied to the signal to generate a precoded signal for transmission over a physical channel. The precoded signal can be transmitted.

Description

[0001] This application is a divisional application of an application which entered the Chinese national phase on January 22, 2019, with PCT application number PCT / US2017 / 044995, international application date August 1, 2017, Chinese application number 201780045502.8, and invention name “Method and apparatus for equal energy codebooks for coupled antennas with transmission lines”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] The present application is related to an application entitled “Method and Apparatus for Optimizing Antenna Precoder Selection with Coupled Antennas” filed on February 4, 2016, which is U.S. application No. 15 / 016,140, ​​with Motorola Mobility Inc. filing number MM01141; an application entitled “Method and Apparatus for Equal Energy Codebooks for Antenna Arrays with Mutual Coupling” filed on September 16, 2015, which is U.S. application No. 14 / 855,693, with Motorola Mobility Inc. filing number MM01601; and an application entitled “Method and Apparatus for Equal Energy Codebooks for Antenna Arrays with Mutual Coupling” filed on May 18, 2016, which is Antenna Arrays with Mutual Coupling)" and U.S. Application No. 15 / 157,754, Motorola Mobility Inc. File No. MM02071-US-NP, all of which are commonly assigned to the applicant of the present application, and are hereby incorporated by reference into this document. Technical Field

[0004] The present disclosure relates to antennas and apparatus for equal energy codebooks for coupled antennas with transmission lines. Background Art

[0005] Currently, wireless communication devices use wireless signals to communicate with other communication devices. Many wireless communication devices have multiple antennas, which can use antenna beamforming to transmit more concentrated signals to receiving devices. Various communication standards define antenna precoder codebooks to support antenna beamforming and or multiple input / multiple output (MIMO) transmissions with feedback from receivers. Telecommunication standards that use precoder codebooks include the Third Generation Partnership Project High Speed ​​Packet Access (3GPP HSPA) and Long Term Evolution (LTE) standards, IEEE 802.11 and 802.16 standards. In all of these standards, the defined precoders have the property that each precoder vector has an equal L2 norm, wherein it is assumed that the precoder is applied to the antenna array in a manner that the precoder with the equal L2 norm produces an antenna pattern with equal power in the far field.

[0006] In each of the above telecommunications standards, precoders are used in conjunction with the transmission of reference symbols from the transmitter so that the receiver can estimate the channel that will result from the application of each precoder. The receiver applies each precoder to the reference symbols in order to estimate the channel quality. It then signals an indication of the best precoder and the corresponding signal quality back to the transmitter. For some transmission modes, the precoder used for signal transmission is signaled to the receiver, which then applies the precoder to estimate the channel for the data symbols.

[0007] Implicit in the operation of these types of systems is the assumption that the precoders are applied in such a way that the antenna patterns corresponding to each precoder have the same transmit power. The reason for this assumption is that the receiver's goal is to select the precoder that maximizes its channel quality and therefore the achievable data rate for a given transmit power. In the case of a single user, this will maximize the transmission range for a fixed data rate, or alternatively, maximize the achievable data rate at a fixed range. Alternatively, for a multi-user system, it is desirable to minimize the transmit power required to achieve a given data rate for each user, since this transmit power appears as interference to all users other than the target user. Summary of the invention

[0008] A method according to the present invention includes: receiving a precoded signal including a reference symbol; estimating a channel for the reference symbol; estimating the channel for the data symbol by obtaining the inner product of the reference symbol channel estimate and the conjugate of the data symbol precoder; and demodulating the received data symbol based on the estimated channel.

[0009] According to an apparatus of the present invention, the apparatus comprises: an antenna array; a transceiver coupled to the antenna array; a controller coupled to the transceiver, the controller being arranged to enable the apparatus to: receive a precoded signal comprising a reference symbol; estimate a channel for the reference symbol; estimate a channel for the data symbol by taking an inner product of a conjugate of a reference symbol channel estimate and a data symbol precoder; and demodulate the received data symbol based on the estimated channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to describe the manner in which the advantages and features of the present disclosure can be obtained, a description of the present disclosure is given by reference to specific embodiments thereof illustrated in the accompanying drawings. These drawings depict only example embodiments of the present disclosure and are therefore not to be construed as limiting the scope thereof. The drawings have been simplified for clarity and are not necessarily drawn to scale.

[0011] Figure 1 is an example block diagram of a system according to a possible embodiment;

[0012] Figure 2 is an example illustration of a Thevenin source with a transmission line and a two-port antenna array model according to a possible embodiment;

[0013] Figure 3 is an example illustration of a matching network between a Thevenin source and an antenna array having an impedance matrix according to a possible embodiment;

[0014] Figure 4 is an example illustration of a combined impedance matrix produced by combining a matching network with an antenna array according to a possible embodiment;

[0015] Figure 5 is an example illustration of the variation of transmitted power as a function of phase for a two-element dipole array with half-wavelength spacing driven by a 50 ohm Thevenin source and a 50 ohm transmission line according to a possible embodiment;

[0016] Figure 6 is an example illustration of a Norton source with a transmission line and a two-port antenna array model according to a possible embodiment;

[0017] Figure 7 is an example illustration of a matching network between a Norton source and an antenna array having an impedance matrix according to a possible embodiment;

[0018] Figure 8 is an example illustration of a combined impedance matrix produced by combining a matching network with an antenna array according to a possible embodiment;

[0019] Fig. 9is an example illustration of the variation of transmitted power as a function of phase for a two-element dipole array with half wavelength spacing driven by a 50 ohm Thevenin source with an isolator and a 50 ohm transmission line according to a possible embodiment;

[0020] Fig.10 is an example flow chart illustrating the operation of a wireless communication device according to a possible embodiment; and

[0021] Fig.11 is an example flow chart illustrating the operation of a wireless communication device according to a possible embodiment.

[0022] Fig.12 is an example block diagram illustrating an apparatus according to a possible embodiment. DETAILED DESCRIPTION

[0023] Embodiments provide methods and apparatus for equal energy codebooks for coupled antennas with transmission lines. According to possible embodiments, multiple precoders can be received from a codebook in a transmitter with an antenna array. Each of the multiple precoders can be transformed into a transform precoder so that the transmit power of each transform precoder is equal to the transmit power of each of the other transform precoders in the multiple precoders. The transmit power can be expressed as a quadratic form relative to the corresponding precoder. The quadratic form can be based on the transmission line impedance of the transmission line between the signal source and the antenna array. A signal can be received from a signal source. A transform precoder in a plurality of transform precoders can be applied to the signal to generate a precoded signal for transmission over a physical channel. The precoded signal can be transmitted.

[0024] Figure 1 1 is an example block diagram of a system 100 according to a possible embodiment. The system 100 may include a transmitting device 110 and a receiving device 120. The transmitting device 110 may be a user equipment (UE), a base station, or any other device that can transmit a wireless signal. Similarly, the receiving device 120 may be a UE, a base station, or any other device that can receive a wireless signal. The UE may be a wireless terminal, a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a personal digital assistant, a device with a subscriber identity module, a personal computer, a selective call receiver, a tablet computer, a laptop computer, or any other device that can send and receive wireless communication signals. The base station may be a wireless wide area network base station, a wireless local area network base station, an enhanced NodeB (eNB), an access point, or any other base station.

[0025] The transmitting device 110 may include a precoder transform controller 112, a codebook 114, and an antenna array 116. The precoder transform controller 112 may be one element or may be distributed between different elements. For example, the precoder transform controller 112 may be part of a processor, may be part of a transceiver, may be part of a precoder, may be part of other elements in the transmitting device, and / or may be distributed between a combination of elements in the transmitting device and / or through cloud computing. The receiving device 120 may include at least one antenna 122. For example, in some embodiments, the receiving device 120 may have one antenna, while in other embodiments, the receiving device 120 may have an array of antennas. Depending on which device is currently transmitting or receiving, the transmitting device 110 may also act as a receiving device, and the receiving device 120 may also act as a transmitting device.

[0026] If there is no mutual coupling of the antenna array 116, such as the transmit array, then what will occur is that antenna precoder vectors with equal L2 norms will produce antenna patterns with equal power (note that some assumptions may be necessary, such as the antennas have equal self-impedance). However, if the antennas in the antenna array 116 are coupled, the antenna patterns produced by two precoders with the same L2 norm may differ by several dB in transmit power. The amount of this difference may depend on a variety of factors, including the mutual coupling coefficient, the type of source used to drive the array, the source impedance, and / or other factors. The power delivered to the antenna array 116 may depend on the relative phase of the inputs to the vector voltage source or the vector current source, on the source impedance, and / or on other factors.

[0027] In the case where a transmission line is used between the source of the source signal 118 and the antenna array 116, the transmit power may vary with the relative phase of the input voltage vector or the input source vector, and the variation may further depend on the source impedance, the transmission line impedance, the length of the transmission line, the antenna impedance (and any matching circuits), and / or other factors. If a transmission line is used between the source and the antenna array 116 in conjunction with an isolator at the source, the transmit power may still vary with the relative phase of the input voltage vector or the input source vector, but the variation may now depend only on the transmission line impedance, the antenna impedance (and any matching circuits), and / or other factors, so that the power variation may no longer depend on the source impedance or the length of the transmission line.

[0028] Embodiments can show that the power variation as a function of the precoder can be expressed as a quadratic form that is non-negatively definite for the case where a transmission line is used between the source and the antenna array. Using these quadratic forms for transmit power, at least two methods can be used to map the precoders to antenna patterns with equal transmit power. In a first method, each precoder can be scaled by the inverse square root of the transmit power generated by the unscaled precoder. In a second method, the precoder set can be transformed by multiplying each precoder by a matrix so that the generated precoder set is all mapped to antenna patterns with the same power. If precoder-based channel estimation is used in combination with common reference symbol-based, the same precoder transformation can also be applied to the common reference symbol precoder.

[0029] Figure 2 is an example illustration 200 of a Thevenin source with a transmission line and a two-port antenna array model according to a possible embodiment. Figure 3 is an example illustration 300 of a matching network between a Thevenin source and an antenna array having an impedance matrix Z according to a possible embodiment. Figure 4 is an example illustration 400 of a combined impedance matrix Z' resulting from a matching network in combination with an antenna array according to a possible embodiment, wherein the combined impedance matrix Z' may be used in place of the impedance matrix Z in equations herein to account for the matching network.

[0030] This embodiment may consider the transmit power with a Thevenin source, a transmission line, and no isolator at the source. For example, diagram 200 shows an antenna array 230 driven by a Thevenin source 210 with a transmission line 220 between the source 210 and the antenna array 230. This may be used to determine the transmit power with a Thevenin source, a transmission line, and no isolator at the source. The Thevenin source 210 may include a Thevenin source with a serial impedance Z S_Thev The ideal vector voltage source v s , where Z S_Thev is a voltage source with voltages v s1 and v s2 The series impedance Z S_Thev1 and Z S_Thev2 The impedance of the transmission line can be expressed as

[0031] Z in (l)=Z0(Z+jZ0I2tan(2πl))(Z0I2+jZtan(2πl)) -1

[0032] Given as , where Z0 may be the impedance of the transmission line, l may be the length of the transmission line in wavelengths, and Z may be the impedance matrix of the combination of the antenna array and any impedance matching circuits between the transmission line and the antenna array.

[0033] The transmit power can be determined by

[0034] Re(v s H (Z S_Thev +Z in (l)) -H Z in (l)(Z S_Thev +Z in (l)) -1 v s )

[0035] =v s H (Z S_Thev +Z in (l)) -H Re(Z in (l))(Z S_Thev +Z in (l)) -1 v S

[0036] Given, where the matrix Z S_Thev can be a diagonal matrix with elements equal to the source impedance in series with the Thevenin voltage source. This expression can be further simplified to a quadratic form:

[0037] v s H (Z S_Thev +Z in (l)) -H Re(Z in (l))(Z S_Thev +Z in (l)) -1 v s

[0038] =v s H Q Thev (z S_Thev , Z in (l))v s ,

[0039] in

[0040] Q Thev (Z S_Thev , Z in (l))=(Z S_Thev +Zin (l)) -H Re(Z in (l))(Z S_Thev +Z in (l)) -1 .

[0041] As an example of a two-element matrix of half-wavelength dipoles with half-wavelength spacing, the impedance matrix of the array can be given by

[0042]

[0043] The following additional parameters for this example may be assumed as follows: source impedance = 50 ohm; transmission line impedance = 50 ohm; and transmission line length = quarter wavelength.

[0044] We can consider v(θ)=[1ex(jθ)] T The L2 norm of the precoder v(θ) is independent of the phase θ for a voltage source of the form θ, so that for all θ,

[0045] ||v(θ)|| 2 =2.

[0046] Figure 5 is an example graph 500 of transmit power as a function of phase θ for a two-element dipole array with half-wavelength spacing driven by a 50 ohm Thevenin source and a 50 ohm transmission line according to a possible embodiment. It can be noted that there is a 1.3 dB variation in transmit power even though the L2 norm of the precoder remains constant.

[0047] Figure 6 is an example illustration 600 of a two-port antenna array model with transmission line Norton sources and according to a possible embodiment. Figure 7 is an example illustration of a matching network between a Norton source and an antenna array with an impedance matrix Z according to a possible embodiment. Figure 8 is an example diagram 800 of a matching network in combination with an antenna array with a resulting combined impedance matrix Z', which may be used in place of the impedance matrix Z in equations herein to account for the matching network, according to a possible embodiment.

[0048] According to this embodiment, the transmission power with a Norton source 610, a transmission line 620, an antenna array 630, and no isolator at the source, considering the impedance of the transmission line can be obtained by

[0049] Z in (l)=Z0(Z+jZ0I2tan(2πl))(Z0I2+jZtan(2πl))-1

[0050] Given as , where Z0 may be the impedance of the transmission line, l may be the length of the transmission line in wavelengths, and Z may be the impedance matrix of the combination of the antenna array and any impedance matching circuits between the transmission line and the antenna array.

[0051] The transmit power can be determined by

[0052] Re(i S H Z S_Nor H (Z S_Nor +Z in (l)) -H Z in (l)(Z S_Nor +Z in (l)) -1 Z S_Nor )i s

[0053] =i S H (Z S_Nor H (Z S_Nor +Z in (l)) -H Re(Z in (l))(Z S_Nor +Z in (l)) -1 Z S_Nor )i S

[0054] Given, where the matrix Z S_Nor can be a diagonal matrix with elements equal to the impedance of the shunt source in parallel with the Norton current source. This expression can be further simplified to a quadratic form:

[0055] i S H (Z S_Nor H (Z S_Nor +Z in (l)) -H Re(Z in (l))(Z S_Nor +Z in (l)) -1 N S_Nor )i S

[0056] =i S H Q Nor (ZS_Nor , Z in (l))i S ,

[0057] in

[0058] Q Nor (Z S_Nor , Z in (l)) = Z S_Nor H (Z S_Nor +Z in (l)) -H Re(Z in (l))(Z S_Nor +Z in (l)) -1 Z S_Nor .

[0059] According to a possible embodiment of transmit power with a Thevenin source, a transmission line, and an isolator at the source, when an isolator is used at the source, the transmitter does not see the voltage and current reflected from the antenna array (and any matching circuit). Instead, the reflected voltage and current are sent away from the transmitter and do not enter the matching load. As a result, the impedance of the transmission line considered may be only the transmission line impedance Z0, and therefore may not depend on the impedance of the antenna array.

[0060] For a Thevenin source, the forward voltage wave entering the transmission line can be given by

[0061] V + =Z0Z S -1 v S

[0062] Given.

[0063] At the antenna array load, the reflected voltage wave can be expressed as

[0064] V - =(Z+Z0I2) -1 (Z-Z0I2)V +

[0065] =SV +

[0066] where S can be the scattering matrix, which is given by

[0067] S=(Z+Z0I2) -1 (Z-Z0I2)

[0068] Given.

[0069] The total voltage at the load can be given by

[0070]

[0071] Given.

[0072] The total current at the load can be given by

[0073] I tot =I + +I - =Z0 -1 (V + -V - )

[0074] =Z0 -1 (I2-S)V +

[0075] =Z0 -1 (I2-S)Z0Z S_Thev v S

[0076] =(I2-S)Z S_The v S

[0077] Given.

[0078] The power delivered to the load can then be given by the quadratic

[0079]

[0080] Given.

[0081] In the case of equal source impedances, this expression for the transmitted power can be expressed as

[0082]

[0083] Or more simply expressed as

[0084] Re(V tot H I tot )=v S H Q Thev_iso (Z0,Z S_Thev , S)v,

[0085] in

[0086]

[0087] Fig. 9is an example graphical representation 900 of transmitted power as a function of phase for a two-element dipole array with half-wavelength spacing driven by a 50 ohm Thevenin source with an isolator and a 50 ohm transmission line according to a possible embodiment. Consider the same example given previously of a two-element matrix of half-wavelength dipoles with half-wavelength spacing. The impedance matrix for this array may be given by

[0088]

[0089] Given.

[0090] As mentioned before, the transmission line impedance can be assumed to be 50 ohms, and v(θ) = [1ex(jθ)] can be considered. T The L2 norm of the precoder v(θ) is independent of the phase θ, so for all θ,

[0091] ||v(θ)|| 2 =2.

[0092] For this example, the variation of transmit power as a function of phase θ is shown in diagram 900. It can be noted that even though the L2 norm of the precoder is kept constant, there is a 1.3 dB variation in transmit power.

[0093] According to a possible embodiment of transmit power with a Norton source, a transmission line, and an isolator at the source, when an isolator is used at the source, the transmitter does not see the voltage and current reflected from the antenna array (and any matching circuit). Instead, the reflected voltage and current are sent away from the transmitter and do not enter the matching load. As a result, the impedance of the transmission line considered may be only the transmission line impedance Z0, and therefore may not depend on the impedance of the antenna array.

[0094] For a Norton source, the forward voltage wave entering the transmission line can be given by

[0095] V + =(Z0I2+Z S_Nor ) -1 Z0Z S_Nor i SS

[0096] Given.

[0097] As in the previous case, the antenna array is loaded and the reflected voltage wave can be given by

[0098] V - =(Z+Z0I2) -1 (Z-Z0I2)V +

[0099] =SV+

[0100] where S can be the scattering matrix, which is given by

[0101] S=(Z+Z0I2) -1 (Z-Z0I2)

[0102] Given.

[0103] The total voltage at the load can be given by

[0104] V tot =V + +V - =(I2+S)V +

[0105] =Z0(I2+S)(Z0I2+Z S_Nor ) -1 Z S_Nor i S

[0106] Given.

[0107] The total current at the load can be given by

[0108] I tot =I + +I - =Z0 -1 (V + -V - )

[0109] =Z0 -1 (I2-S)V +

[0110] =Z0 -1 (I2-S)Z0Z S_THev v S

[0111] =(I2-S)Z S_Thev v S

[0112] Given.

[0113] The power delivered to the load can therefore be given by the quadratic

[0114]

[0115] Given.

[0116] In the case of equal source impedances, this expression for the transmitted power can be expressed as

[0117] Or more simply expressed as

[0118] Re(V tot H I tot )=i S H Q Nor_iso (Z0,Z S_Nor , S)i,

[0119] in

[0120]

[0121] According to a possible embodiment of power variation of precoders with equal Euclidean norm, in the above four cases, the transmit power can be expressed as a quadratic form relative to the current or voltage used to drive the antenna array. Obviously, even if the Euclidean norm of the precoder is kept constant, the transmit power can be varied as a function of the relative phase of the input voltage or input current. As a result, the implicit assumption used in the design of 3GPP LTE and IEEE 802.16 codebooks - that precoders with equal Euclidean norm map to antenna patterns with equal transmit power - is incorrect when the antennas are coupled and a transmission line is used between the transmitter and the antenna array.

[0122] Two methods can be used to map precoders with equal Euclidean norms to antenna patterns with equal power. In the first method, a separate real-valued scaling can be applied to each precoder so that the transmit power is equalized. For example, for the case where a Thevenin source is used to drive the array and an isolator is used at the transmitter, the transmit power can be given by

[0123] Re(V tot H I tot )=v S H Q Thev_iso (Z0,Z S_Thev , S)v

[0124] Given.

[0125] To equalize the transmit power for precoders with equal Euclidean norm, we can k，norm Defined as:

[0126]

[0127] Precoder v k can be normalized to the normalized precoder v k，norm, where α is a constant that is the same for all precoders. It should be noted that some equivalent variables in the equivalent equations throughout the present disclosure may be different for ease of description in the corresponding section. In this method, the receiver should know the scaling factor applied to each precoder. In particular, the scaling factor for each precoder should be signaled to the receiver. For example, for the kth precoder, the scaling factor

[0128]

[0129] can be sent to the receiver. There are other ways to signal the scaling information to the receiver. For example, the parameter α and the matrix

[0130] Q Thev_iso (Z0,Z S_Thev , S)

[0131] can be used to send a signal to the receiver. Thev_iso It can be Hermitian, so the matrix coefficients can be signaled to the receiver in the form of Mx(M-1) / 2 complex values ​​and M real values, where M can be the number of transmit antennas.

[0132] For the second method, the transformation can be performed on the precoders of equal Euclidean norm so that the transformed precoders can all be mapped to antenna patterns with equal power. For this reason, Q Thev_iso can be factorized into

[0133] Q Thev_iso (Z0,Z S_Thev , S) = PP H ,

[0134] where the factorization may be non-unique. One factorization of this type is the Cholesky factorization, where the matrix P may be a lower triangular matrix (and thus P H can be an upper triangular matrix). Other factorizations of this form can be generated as follows: Note that due to Q Thev_iso can be Hermitian, so Q Thev_iso The eigendecomposition of can have the following form

[0135] Q Thev_iso =UΛUH,

[0136] The columns of U can be Q Thev_iso The eigenvectors of and the matrix Λ can be a diagonal matrix. The diagonal elements of Λ can be corresponding to Q Thev_isoThe eigenvalues ​​of the eigenvectors of , where the eigenvalues ​​in Λ can be in the same order as the corresponding eigenvectors in U. Using this eigendecomposition, the following definitions can be made:

[0137] P=UΛ 1 / 2 ,

[0138] where Λ 1 / 2 is the square root of the matrix Λ. It can be noted that the matrix Q Thev_iso The eigendecomposition of may not be unique, since the eigenvectors forming the columns of U can be arranged in any order. Thev The size of is MxM, then Q Thev_iso There are M eigenvectors, and there are M (M! = M*(M-1)*(M-2)*…*) possible orderings of the factors of these eigenvectors. Similarly, given the matrix U and the diagonal matrix Λ of the corresponding eigenvalues, the square root matrix Λ 1 / 2 can be non-unique because each eigenvalue has both a positive and a negative square root (Q Thev_iso All eigenvalues ​​of are non-negative). Therefore, given the matrix Λ, there can be 2 M Possible matrices Λ 1 / 2 However, given a matrix Λ, there is only one matrix Λ where all values ​​are non-negative 1 / 2 , and this matrix can be called a positive square root.

[0139] For the remainder of this section, the following definitions apply:

[0140] P=UΛ 1 / 2 ,

[0141] where Λ 1 / 2 is the positive square root of the matrix Λ. The Q Thev_iso The order of the eigenvectors of may not be important, but the order of the eigenvalues ​​in Λ should correspond to the order of the eigenvectors in U. It can be noted that since the eigenvectors are orthogonal, it follows that:

[0142] P -H =UΛ -1 / 2 .

[0143] Now define

[0144] v S =P -H w

[0145] =UΛ -1 / 2 w,

[0146] Thus v s is w to Q scaled by the inverse square root of the corresponding eigenvalue Thev_isoThe sum of the projections on the eigenvectors of . Note that

[0147]

[0148] As long as the reference symbol precoder uses the same transform as the data symbol precoder, the receiver can use the existing precoder to estimate the channel, and the receiver does not need to know the precoder transform used at the receiver. And transformed into voltage vector v s , then as long as the precoder has the same norm L 2 , all precoders can be mapped to equal energy modes.

[0149] The described method for mapping precoders of equal Euclidean norm to antenna patterns with equal power can be used for all four cases given above, where the transmitter power is a quadratic form with respect to the vector voltage (for Thevenin source) or the vector current (for the Norton source). Therefore, the embodiments can be applied to at least the following four cases considered in the present disclosure: the transmit power with a Thevenin source, a transmission line, and no isolator at the source; the transmit power with a Norton source, a transmission line, and no isolator at the source; the transmit power with a Thevenin source, a transmission line, and an isolator at the source; the transmit power with a Norton source, a transmission line, and an isolator at the source.

[0150] Fig.10 1000 is an example flow chart illustrating the operation of a wireless communication device such as a transmitting device 110 and / or a receiving device 120 according to possible embodiments. For example, the method of flow chart 1000 can be used in the case of using a transmission line without an isolator, in the case of using an isolator at a source of a signal for transmission along a transmission line, and in other cases. At 1010, a plurality of precoders can be received from a codebook in a transmitter having an antenna array.

[0151] At 1020, each of the plurality of precoders may be transformed into a transform precoder so that the transmit power of each transform precoder is equal to the transmit power of each of the other transform precoders in the plurality of precoders. The transmit power may be expressed as a quadratic form relative to the corresponding precoder. The quadratic form may be non-negative definite. The quadratic form may be based on the transmission line impedance of the transmission line between the signal source and the antenna array. The quadratic form may also be based on the impedance matrix of the antenna array. This may be used when an isolator is used at the source of the signal for transmission, and may also be used when an isolator is not used. The quadratic form may also be based on a matching network between the signal source and the antenna array. The matching network may transform the impedance matrix of the antenna array to improve power transfer between the source and the antenna array. The quadratic form may be further based on the impedance of the antenna array, the signal source impedance, and the length of the transmission line. For example, the quadratic form may be based on the length of the transmission line when an isolator is not used at the signal source. In addition, the quadratic form can be a function of the transmission line impedance of the transmission line between the signal source and the antenna array, the impedance of the source of the signal used for transmission, the impedance matching network, the scattering matrix, and other information, where the quadratic form can be a function of some or all of this information.

[0152] The transformation can equalize the transmit power for all of the multiple precoders. The transformation can also transform the precoders to equalize the energy precoders when a transmission line is used between the source of the signal and the antenna array. In addition, both the data symbol precoder and the reference symbol precoder can be transformed by the same transformation.

[0153] Each precoder may be transformed by scaling each precoder by the inverse square root of the transmit power generated from the corresponding precoder before applying the scaling. Scaling may include normalizing the precoder to a normalized precoder based on a quadratic form. For example, scaling may include normalizing the precoder based on a quadratic form.

[0154]

[0155] The precoder w k Normalized to the normalized precoder v S,norm , where α can be a constant that is the same for all precoders and Q Thev_iso It can be a matrix, which can be used as the scattering matrix S, the impedance Z of the source of the transmitted signal S_Thev , and the transmission line impedance Z0 of the transmission line. The scattering matrix S can be a function of the impedance matrix of the antenna array. This equation can cover the case of using a Thevenin source with an isolator. Other similar equations can cover other cases, such as when using a Norton source, when not using an isolator, and other cases.

[0156] Scattering parameters may or may not be used in the case where an isolator is not used at the source. Scattering parameters may depend on the transmission line impedance, antenna impedance, and any matching circuits. If an isolator is used at the source, the quadratic form of the transmitted power may be based only on the scattering parameters without separate knowledge of the transmission line impedance and the impedance matrix of the antenna array. In the case where there is no isolator at the source, the transmission line impedance and the antenna array impedance may be used alone. In the case where an isolator is used at the source, the power variation may depend only on the scattering matrix without additional separate knowledge of the transmission line impedance and the antenna array impedance.

[0157] Additionally or alternatively, each precoder may be transformed by multiplying each precoder by a transformation matrix such that the resulting set of precoders each maps to an antenna pattern having the same power. The transformation matrix may be based on an impedance matrix for the antenna array, which is considered at the signal source as a function of the transmission line length, the transmission line impedance, and the impedance of the antenna array. The transmission line length may be measured in units of wavelengths. The transformation matrix may also be based on a diagonal matrix of transmitter source impedances. As an example of a Thevenin source model, the transmitter may include a transmitter source for a transmitted signal and the transformation may be based on

[0158]

[0159] where w can be a precoder from the set of precoders, v s can be a transform precoder about voltage, and P Thev Can be based on

[0160]

[0161] in

[0162]

[0163] where l can be the length of the transmission line measured in wavelengths, and Z S Thev can be a diagonal matrix of the transmitter source impedance, and Z in may be the impedance matrix of the antenna array considered as a function of the transmission line length, the transmission line impedance, and the impedance of the antenna array at the source. s It can be composed of two voltage sources v s1 and v s2 This equation can be used for the Thevenin source model, while another similar equation can be used for the Norton source model.

[0164] As an example of a Norton source model, the transmitter may include a transmitter source for a transmitted signal and the transformation may be based on

[0165]

[0166] where w may be a precoder from a set of precoders, i may be a transform precoder, and P Nor Can be based on

[0167]

[0168] in

[0169] Q Nor (Z S_Nor , Z in (l)) = Z S_Nor H (Z S_Nor +Z in (l)) -H Re(Z in (l))(Z S_Nor +Z in (l)) -1 Z S_Nor ,

[0170] where can be the transmission line length measured in wavelengths, Z S_Nor can be a diagonal matrix of the transmitter source impedance, and Z in may be the impedance matrix of the antenna array seen as a function of the transmission line length, the transmission line impedance, and the impedance of the antenna array at the source.

[0171] At 1030, a signal may be received from a signal source. At 1040, a transform precoder of a plurality of transform precoders may be applied to the signal to generate a precoded signal for transmission over a physical channel. At 1050, the precoded signal may be transmitted. At 1060, a scaling factor for scaling may be transmitted.

[0172] Fig.111100 is an example flow chart illustrating the operation of a wireless communication device, such as a transmitting device 110 and / or a receiving device 120, according to possible embodiments. At 1110, a precoded signal including a reference symbol can be received. At 1120, a channel for the reference symbol can be estimated. At 1130, the channel for the data symbol can be estimated by taking the inner product of the reference symbol channel estimate and the conjugate of the data symbol precoder. The channel estimation for the reference symbol and the data symbol can be performed when an antenna array is used to receive the precoded signal. For example, when a device including the antenna array is transmitting, it can transmit the precoded signal, and when the device is receiving, it can receive the precoded signal. At 1140, the received data symbol can be demodulated based on the estimated channel.

[0173] It should be understood that, although specific steps are shown in the figures, one or more specific steps may be rearranged, repeated or completely omitted according to the embodiment. Moreover, some of the steps performed may be repeated simultaneously on an uninterrupted or continuous basis while performing other steps. In addition, different steps may be performed by different elements or a single element of the disclosed embodiment.

[0174] Fig.12 1 is an example block diagram of an apparatus 1200 such as a transmitting device 110 according to a possible embodiment. The apparatus 1200 may be a base station, a UE, or any other transmitting and / or receiving device. The apparatus 1200 may include a housing 1210, a controller 1220 coupled to the housing 1210, an audio input and output circuit 1230 coupled to the controller 1220, a display 1240 coupled to the controller 1220, a transceiver 1250 coupled to the controller 1220, an antenna array including multiple antennas, such as antennas 1255 and 1257, coupled to the transceiver 1250, a user interface 1260 coupled to the controller 1220, a memory 1270 coupled to the controller 1220, and a network interface 1280 coupled to the controller 1220. The apparatus 1200 may perform the methods described in all embodiments.

[0175] The display 1240 may be a viewfinder, a liquid crystal display (LCD), a light emitting diode (LED) display, a plasma display, a projection display, a touch screen, or any other device that displays information. The transceiver 1250 may include a transmitter and / or a receiver. The transceiver 1250 may also include a signal source, or the signal source may be located elsewhere on the device 1200. The plurality of antennas 1255 and 1257 may be antenna arrays. A transmission line (not shown) may be coupled between the signal source 1252 and the antenna array. The transmission line may have a transmission line impedance. The plurality of antennas 1255 and 1257 may include two or more antennas. The antennas 1255 and 1257 may be coupled to each other, wherein a voltage or current applied to one antenna element induces a voltage or current on another antenna element in the antenna array. The audio input and output circuit 1230 may include a microphone, a speaker, a transducer, or any other audio input and output circuit. The user interface 1260 may include a keypad, a keyboard, a button, a touch pad, a joystick, a touch screen display, another additional display, or any other device that can be used to provide an interface between a user and an electronic device. The network interface 1280 may be a universal serial bus (USB) port, an Ethernet port, an infrared transmitter / receiver, an IEEE 1398 port, a WLAN transceiver, or any other interface that can connect the device to a network, device, or computer and can transmit and receive data communication signals. The memory 1270 may include random access memory, read-only memory, optical memory, flash memory, removable memory, a hard drive, a cache, or any other memory that can be coupled to a wireless communication device.

[0176] The device 1200 or the controller 1220 may implement any operating system, such as MICROSOFT or Android TM , or any other operating system. The device operating software may be written in any programming language, such as C, C++, Java, or Visual Basic, as examples. The device software may also run on an application framework, such as frame, Framework, or any other application framework. Software and / or operating system may be stored in memory 1270 or elsewhere on device 1200. Device 1200 or controller 1220 may also use hardware to implement the disclosed operations. For example, controller 1220 may be any programmable processor. The disclosed embodiments may also be implemented on general or special purpose computers, programmed microprocessors or microprocessors, peripheral integrated circuit elements, application specific integrated circuits or other integrated circuits, hardware / electronic logic circuits such as discrete element circuits, programmable logic devices such as programmable gate arrays, field programmable gate arrays, etc. In general, controller 1220 may be any one or more controllers or processor devices capable of operating a wireless communication device and implementing the disclosed embodiments. Although controller 1220 is illustrated as a box, the operations of controller 1220 may be performed in one element, and controller 1220 may alternatively be distributed among different elements of device 1200 and distributed through cloud computing. For example, different controllers may exist on device 1200 to perform different operations for different elements on device 1200, a main controller may perform all operations of device 1200, and / or a main controller may perform some overall operations and distributed controllers may perform other operations for other elements on device 1200.

[0177] In operation, the memory 1270 may store a codebook including a plurality of precoders. The controller 1220 may receive the plurality of precoders from the codebook in the memory 1270.

[0178] The controller 1220 may transform each of the plurality of precoders into a transform precoder so that the transmit power of each precoder is equal to the transmit power of other transform precoders in the plurality of precoders. The transmit power may be expressed as a quadratic form relative to the corresponding precoder. The quadratic form may be based on the transmission line impedance. The quadratic form may also be based on the impedance matrix of the antenna array, the matching network between the signal source and the antenna array, the impedance of the transmission line, the signal source impedance, and / or the length of the transmission line.

[0179] Each precoder may be transformed by scaling each precoder by the inverse square root of the transmit power generated from the corresponding precoder before applying the scaling. Scaling may include normalizing the precoder to a normalized precoder based on a quadratic form. Also or alternatively, each precoder may be transformed by multiplying each precoder by a transformation matrix so that the resulting set of precoders each maps to an antenna pattern with the same power. The transformation matrix may be based on an impedance matrix of the antenna array, which is viewed at the signal source as a function of the transmission line length, the transmission line impedance, and the impedance of the antenna array.

[0180] The controller 1220 may receive a signal from a signal source 1252. The controller 1220 may apply a transform precoder of a plurality of transform precoders to the signal to generate a precoded signal for transmission over a physical channel. The transceiver 1250 may transmit the precoded signal.

[0181] The method of the present disclosure can be implemented on a programmed processor. However, the controller, flow chart and modules can also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, integrated circuits, hardware electronic or logic circuits such as discrete component circuits, programmable logic devices, etc. In general, any device on which a finite state machine capable of implementing the flow chart shown in the figure resides can be used to implement the processor functions of the present disclosure.

[0182] Although the present disclosure has been described using its specific embodiments, it is apparent that many alternatives, modifications and variations will be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added or replaced in other embodiments. Moreover, all elements in each of the accompanying drawings are not necessary for the operation of the disclosed embodiments. For example, a person skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements in the independent claims. Therefore, the embodiments of the present disclosure as given herein are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0183] In this article, relational terms such as "first", "second", etc. can only be used to distinguish between one entity or action and another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The phrases "at least one of...", "at least one selected from the group of...", "at least one selected from..." following a list are defined to represent one, some or all of the elements in the list, but not necessarily all. The terms "comprises", "comprising", "including", or any other variations thereof are intended to cover non-exclusive inclusion, so that the process, method, article, or device including a series of elements does not only include those elements, but may include other elements that are not explicitly listed or inherent to such a process, method, article, or device. In the absence of more restrictions, the elements that were previously "one", "an", etc. do not exclude the presence of other identical elements in the process, method, article, or device including the element. Moreover, the term "another" is defined as at least the second or more. As used herein, the terms "include", "have", etc. are defined as "include". In addition, the background technology section is written as the inventor's own understanding of the background of some embodiments at the time of filing, and includes the inventor's own recognition of any problems existing in the prior art and / or problems experienced in the inventor's own work.

[0184] Furthermore, further aspects of the invention are provided by the subject matter of the following items:

[0185] 1. A method comprising:

[0186] receiving a plurality of precoders from a codebook in a transmitter having an antenna array;

[0187] transforming each of the plurality of precoders into a transform precoder such that a transmit power of each transform precoder is equal to a transmit power of each of the other transform precoders in the plurality of precoders, wherein the transmit power is expressed as a quadratic form relative to the corresponding precoder, wherein the quadratic form is based on a transmission line impedance of a transmission line between a signal source and the antenna array;

[0188] receiving a signal from the signal source;

[0189] applying a transform precoder from among the plurality of transform precoders to the signal to generate a precoded signal for transmission over a physical channel; and

[0190] The precoded signal is transmitted.

[0191] 2. A method according to clause 1, wherein the quadratic form is also based on an impedance matrix of the antenna array.

[0192] 3. A method according to item 1, wherein the quadratic form is also based on a matching network between the signal source and the antenna array.

[0193] 4. The method of clause 1, wherein the quadratic form is further based on an impedance of the antenna array, a signal source impedance, and a length of the transmission line.

[0194] 5. A method according to clause 1, wherein each precoder is transformed by scaling each precoder by the inverse square root of the transmit power resulting from the corresponding precoder before applying the scaling.

[0195] 6. A method according to clause 5, wherein scaling comprises normalizing the precoder into a normalized precoder based on the quadratic form.

[0196] 7. The method according to clause 5, further comprising transmitting a scaling factor used for said scaling.

[0197] 8. A method according to clause 1, wherein each precoder is transformed by multiplying each precoder by a transformation matrix so that the resulting set of precoders each maps to an antenna pattern with the same power.

[0198] 9. A method according to clause 8, wherein the transformation matrix is ​​based on an impedance matrix of the antenna array, the impedance matrix being considered at the signal source as a function of transmission line length, transmission line impedance, and impedance of the antenna array.

[0199] 10. A method according to clause 1, wherein the transform equalizes the transmit power of all of the plurality of precoders.

[0200] 11. A method according to clause 1, wherein when a transmission line is used between a source of the signal and the antenna array, the transformation transforms the precoder into an equal energy precoder.

[0201] 12. A method according to clause 1, wherein both the data symbol precoder and the reference symbol precoder are transformed by the same transform.

[0202] 13. The method according to item 12, further comprising:

[0203] receiving a precoded signal including reference symbols;

[0204] estimating a channel for the reference symbols;

[0205] estimating a channel for the data symbol by taking the inner product of a reference symbol channel estimate and a conjugate of a data symbol precoder; and

[0206] The received data symbols are demodulated based on the estimated channel.

[0207] 14. An apparatus comprising:

[0208] Antenna arrays;

[0209] a transceiver coupled to the antenna array;

[0210] a signal source coupled to the transceiver;

[0211] a transmission line coupled between the signal source and the antenna array, the transmission line having a transmission line impedance;

[0212] a memory storing a codebook including a plurality of precoders; and

[0213] A controller coupled to the transceiver and the memory and configured to:

[0214] receiving a plurality of precoders from the codebook;

[0215] transforming each of the plurality of precoders into a transform precoder such that a transmit power of each transform precoder is equal to a transmit power of each of the other transform precoders in the plurality of precoders, wherein the transmit power is expressed as a quadratic form relative to the corresponding precoder, wherein the quadratic form is based on the transmission line impedance;

[0216] receiving a signal from the signal source;

[0217] applying a transform precoder from among the plurality of transform precoders to the signal to generate a precoded signal for transmission over a physical channel;

[0218] Wherein, the transceiver transmits the precoded signal.

[0219] 15. An apparatus according to item 15, wherein the quadratic form is also based on at least one selected from the following: an impedance matrix of the antenna array, a matching network between the signal source and the antenna array, an impedance of the antenna array, a signal source impedance, and a length of the transmission line.

[0220] 16. An apparatus according to clause 14, wherein each precoder is transformed by scaling each precoder by the inverse square root of the transmit power resulting from the corresponding precoder before applying the scaling.

[0221] 17. An apparatus according to clause 16, wherein scaling comprises normalizing the precoder into a normalized precoder based on the quadratic form.

[0222] 18. An apparatus according to clause 14, wherein each precoder is transformed by multiplying each precoder by a transformation matrix such that the resulting set of precoders each maps to an antenna pattern having the same power.

[0223] 19. An apparatus according to clause 18, wherein the transformation matrix is ​​based on an impedance matrix of the antenna array, the impedance matrix being considered at the signal source as a function of transmission line length, transmission line impedance, and impedance of the antenna array.

[0224] 20. An apparatus according to clause 14, wherein the controller transforms the precoder into an equal energy precoder when a transmission line is used between a source of the signal and the antenna array.

Claims

1. A method for equal energy codebooks for coupled antennas with a transmission line, the method comprising: receiving a precoded signal including a reference symbol, wherein a transmit power of each transform precoder is equal to a transmit power of each of the other transform precoders in the plurality of precoders by transforming each precoder in a plurality of precoders into a plurality of transform precoders, wherein the transmit power is expressed as a quadratic form relative to the corresponding precoder, wherein the quadratic form is based on a transmission line impedance of a transmission line between a signal source and an antenna array, wherein one of the plurality of transform precoders is applied to a signal to generate the precoded signal; estimating a channel for the reference symbols; estimating a channel for a data symbol by taking the inner product of a reference symbol channel estimate and a conjugate of a data symbol precoder; and The received data symbols are demodulated based on the estimated channel.

2. The method according to claim 1, wherein: When the antenna array is used to receive a precoded signal, channels for the reference symbols and the data symbols are estimated.

3. The method according to claim 1, wherein: The quadratic form is also based on an impedance matrix of the antenna array.

4. The method according to any one of claims 1 to 3, wherein: The quadratic form is also based on a matching network between the signal source and the antenna array.

5. The method according to any one of claims 1 to 3, wherein: The quadratic form is also based on the impedance of the antenna array, the signal source impedance, and the length of the transmission line.

6. The method according to any one of claims 1 to 3, wherein: Each precoder is transformed by scaling it by the inverse square root of the transmit power resulting from the corresponding precoder before applying the scaling.

7. The method according to claim 6, wherein: Scaling includes normalizing the precoder into a normalized precoder based on the quadratic form. The method of claim 6 , further comprising transmitting a scaling factor used for the scaling.

9. The method according to any one of claims 1 to 3, wherein: Each precoder is transformed by multiplying it by a transformation matrix such that the resulting set of precoders each maps to an antenna pattern with the same power.

10. The method according to claim 9, wherein: The transformation matrix is ​​based on an impedance matrix of the antenna array, which is considered at the signal source as a function of transmission line length, transmission line impedance, and impedance of the antenna array.

11. The method according to any one of claims 1 to 3, wherein: The transforming equalizes the transmit power of all of the plurality of precoders.

12. The method according to any one of claims 1 to 3, wherein: The transform transforms the precoder into an equal energy precoder when a transmission line is used between a source of the signal and the antenna array.

13. An apparatus for equal energy codebooks for coupled antennas with a transmission line, comprising: Antenna Array (1255); a transceiver (1250) coupled to the antenna array (1255); A controller (1220) coupled to the transceiver (1250), the controller (1220) being arranged to cause the apparatus (1200): receiving a precoded signal including a reference symbol, wherein a transmit power of each transform precoder is equal to a transmit power of each of the other transform precoders in the plurality of precoders by transforming each precoder in a plurality of precoders into a plurality of transform precoders, wherein the transmit power is expressed as a quadratic form relative to the corresponding precoder, wherein the quadratic form is based on a transmission line impedance of a transmission line between a signal source and the antenna array, wherein one of the plurality of transform precoders is applied to the signal to generate the precoded signal; estimating a channel for the reference symbols; estimating a channel for a data symbol by taking the inner product of a reference symbol channel estimate and a conjugate of a data symbol precoder; and The received data symbols are demodulated based on the estimated channel.

14. The device according to claim 13, wherein: When the antenna array is used to receive a precoded signal, channels for the reference symbols and the data symbols are estimated.

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