Methods, devices, and computer-readable media for channel state information transmission

Abstract

Embodiments of the present disclosure relate to methods, devices, and computer readable media for channel state information (CSI) transmission. In an example embodiment, a method for communication includes determining a payload of channel state information for at least one transmission layer, the at least one transmission layer being used for communication between a terminal device and a network device; responsive to determining that the payload exceeds a capacity of available uplink resources, discarding a portion of the channel state information, the discarded portion including at least an indication specific to one of the at least one transmission layer; and transmitting a remaining portion of the channel state information to the network device.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to the field of communications, and more particularly to methods, devices and computer readable media for channel state information (CSI) transmission. BACKGROUND

[0002] Communication techniques have been developed in various communication standards to provide a common protocol that enables different wireless devices to communicate at a municipal, national, regional, or even global level. One example of an emerging communication standard is New Radio (NR), such as 5G radio access. NR is a set of enhancements to the third generation partnership project (3GPP)’s long-term evolution (LTE) mobile standard. It is designed to provide improved mobile broadband Internet access with reduced cost, improved services and a better user experience with lower battery consumption than previous generations of wireless systems. NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0003] In a communication system, channel state information (CSI) of a communication channel between a terminal device and a network device is typically estimated at the receiving terminal device and fed back to the network device to enable the network device to control transmissions based on current channel conditions indicated by the CSI. According to NR technology, it has been proposed to report channel properties for wideband and subbands as well as different beams (in MIMO systems) in the CSI, which results in a large overhead for CSI transmission. SUMMARY

[0004] Generally, example embodiments of the present disclosure provide methods, devices and computer readable media for CSI transmission.

[0005] In a first aspect, a method for communication is provided. The method comprises determining a payload of channel state information for at least one transmission layer, the at least one transmission layer being used for communication between a terminal device and a network device; in response to determining that the payload exceeds a capacity of available uplink resources, discarding a portion of the channel state information, the discarded portion comprising at least an indication specific to one of the at least one transmission layer; and transmitting a remaining portion of the channel state information to the network device.

[0006] In a second aspect, a method for communication is provided. The method comprises determining an ordered subset of frequency domain (FD) bases for at least one transmission layer configured for communication between a terminal device and a network device, the ordered subset of FD bases being selected from an ordered set of FD bases; determining an intermediate set of FD bases based on the ordered subset of FD bases by a shifting operation; and transmitting at least a number indication indicating a number of FD bases in the intermediate set to the network device as part of channel state information.

[0007] In a third aspect, a method for communication is provided. The method comprises determining a plurality of subbands for a terminal device, the plurality of subbands being consecutively distributed in a frequency domain or uniformly spaced in the frequency domain; and transmitting a subband indication for the plurality of subbands to the terminal device to enable channel state estimation by the terminal device on the plurality of subbands.

[0008] In a fourth aspect, a method for communication is provided. The method comprises receiving a subband indication for a plurality of subbands from a network device, the plurality of subbands being consecutively distributed in a frequency domain or uniformly spaced in the frequency domain; determining the plurality of subbands based on the subband indication; and performing channel state estimation on the plurality of subbands.

[0009] In a fifth aspect, a device is provided. The device comprises a processor; and a memory coupled to the processing unit and having instructions stored thereon that, when executed by the processing unit, cause the device to perform the method according to the first aspect.

[0010] In a sixth aspect, a device is provided. The device comprises a processor; and a memory coupled to the processing unit and having instructions stored thereon that, when executed by the processing unit, cause the device to perform the method according to the second aspect.

[0011] In a seventh aspect, a device is provided. The device comprises a processor; and a memory coupled to the processing unit and having instructions stored thereon that, when executed by the processing unit, cause the device to perform the method according to the third aspect.

[0012] In an eighth aspect, a device is provided. The device comprises a processor; and a memory coupled to the processing unit and having instructions stored thereon that, when executed by the processing unit, cause the device to perform the method according to the fourth aspect.

[0013] In a ninth aspect, a computer readable medium having instructions stored thereon that, when executed on at least one processor, cause the at least one processor to perform the method according to the first aspect.

[0014] In a tenth aspect, there is provided a computer readable medium having instructions stored thereon, which when executed on at least one processor, cause the at least one processor to perform the method according to the second aspect.

[0015] In an eleventh aspect, there is provided a computer readable medium having instructions stored thereon, which when executed on at least one processor, cause the at least one processor to perform the method according to the third aspect.

[0016] In a twelfth aspect, there is provided a computer readable medium having instructions stored thereon, which when executed on at least one processor, cause the at least one processor to perform the method according to the fourth aspect.

[0017] Other features of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1 is a schematic diagram of a communication environment in which embodiments according to some aspects of the present disclosure can be implemented;

[0020] Figure 2 is a schematic diagram illustrating a procedure of subband indication transmission according to some embodiments of the present disclosure;

[0021] Figure 3A is a schematic diagram illustrating a plurality of subbands according to some embodiments of the present disclosure;

[0022] Figure 3B is a schematic diagram illustrating a plurality of subbands according to some embodiments of the present disclosure;

[0023] Figure 4 is a schematic diagram illustrating a procedure of CSI transmission according to some embodiments of the present disclosure;

[0024] Figure 5A is a schematic diagram illustrating dropping of CSI according to some embodiments of the present disclosure;

[0025] Figure 5B is a schematic diagram illustrating dropping of CSI according to some embodiments of the present disclosure;

[0026] Figure 6 is a schematic diagram illustrating change of CSI according to some embodiments of the present disclosure;

[0027] Figure 7 is a schematic diagram illustrating a procedure of CSI compression according to some embodiments of the present disclosure;

[0028] Figure 8 A schematic diagram illustrating FD basis selection according to some embodiments of the disclosure is shown;

[0029] Figure 9A A schematic diagram illustrating FD basis selection according to some embodiments of the disclosure is shown;

[0030] Figure 9B A schematic diagram illustrating FD basis selection according to some embodiments of the disclosure is shown;

[0031] Figure 10 A flow diagram of an example method according to some embodiments of the disclosure is shown;

[0032] Figure 11 A flow diagram of an example method according to some embodiments of the disclosure is shown;

[0033] Figure 12 A flow diagram of an example method according to some embodiments of the disclosure is shown;

[0034] Figure 13 A flow diagram of an example method according to some embodiments of the disclosure is shown; and

[0035] Figure 14 is a simplified block diagram of a device suitable for implementing embodiments of the disclosure.

[0036] Throughout the drawings, identical or similar reference numerals can designate identical or similar elements. DETAILED DESCRIPTION

[0037] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that these embodiments are described only for the purpose of explanation and to help the person skilled in the art understand and implement the present disclosure, and do not imply any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0038] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0039] As used herein, the term “network device” or “base station” (BS) refers to a device that is capable of providing or hosting a cell or coverage in which terminal devices can communicate. Examples of network devices include, but are not limited to, a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), a Node B in New Radio Access (gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a low power node (such as a femto node, a pico node, etc.). For purposes of discussion, some embodiments will be described below with reference to a gNB as an example of a network device.

[0040] As used herein, the term “terminal device” refers to any device with wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, a user equipment (UE), a personal computer, a desktop computer, a mobile computer, a cellular phone, a smart phone, a personal digital assistant (PDA), a portable computer, an image capture device (such as a digital camera), a gaming device, a music storage and playback appliance, or an Internet appliance with wireless or wired Internet access and browsing capabilities, etc.

[0041] As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and variations thereof are to be construed as open terms meaning “includes, but is not limited to.” The term “based on” is to be construed as “based at least in part on.” The term “one embodiment” and “an embodiment” are to be construed as “at least one embodiment.” The term “another embodiment” is to be construed as “at least one other embodiment.” The terms “first,” “second,” etc. can refer to different or the same objects. Other definitions (explicit and implicit) can be included below.

[0042] In some examples, a value, process, or apparatus is referred to as “optimal,” “minimum,” “maximum,” “smallest,” “largest,” etc. It will be understood that such descriptions are intended to indicate that a choice can be made among many used functional alternatives, and that such a choice need not be better, smaller, larger, or otherwise more desirable than other choices.

[0043] In NR Release 15, a codebook defined for transmission using one beam is referred to as a Type I codebook. A terminal device reports CSI for one beam, and a subband parameter is reported. When available resources are insufficient to transmit the CSI, the terminal device can discard some of the CSI by subband. For example, parameters related to even subbands can be discarded first.

[0044] Recently, in NR, a terminal device needs to report CSI for more than one beam (e.g., L beams), and the corresponding codebook is referred to as a Type-II codebook, which is enhanced by frequency domain compression. Unlike a Type-I codebook, there is no subband parameter according to a Type-II codebook. Therefore, it is necessary to handle CSI transmission for a Type-II codebook, including omission and compression of overhead for the CSI transmission.

[0045] Embodiments of the present disclosure provide a solution for CSI transmission to address one or more of the above-mentioned omission and compression issues of CSI transmission and other potential issues. The following will be described in conjunction with Figures 1-13 The principles and implementations of the present disclosure are described in detail.

[0046] Figure 1 An example communication network 100 in which implementations of the present disclosure can be implemented is shown. The network 100 includes a network device 110 and a terminal device 120 served by the network device 110. The service area of the network device 110 is referred to as a cell 102. It can be understood that the number of network devices and terminal devices is for illustrative purposes only, and does not imply any limitation. The network 100 can include any suitable number of network devices and terminal devices suitable for implementing implementations of the present disclosure. Although not shown, it should be understood that one or more terminal devices can be located in the cell 102 and served by the network device 110.

[0047] In the communication network 100, the network device 110 can transmit data and control information to the terminal device 120, and the terminal device 120 can also transmit data and control information to the network device 110. The link from the network device 110 to the terminal device 120 is referred to as the downlink (DL) or forward link, while the link from the terminal device 120 to the network device 110 is referred to as the uplink (UL) or reverse link.

[0048] Depending on the communication technology, the network 100 can be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Access (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency Division Multiple Access (OFDMA) network, a Single-Carrier Frequency Division Multiple Access (SC-FDMA) network, or any other network. The communication discussed in the network 100 can comply with any suitable standards, including but not limited to New Radio Access (NR), Long Term Evolution (LTE), Evolved LTE, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, Global System for Mobile Communications (GSM), etc. Also, the communication can be performed according to any generation of communication protocol that is currently known or developed in the future. Examples of the communication protocol include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols. The techniques described herein can be used for the above wireless networks and radio technologies, as well as other wireless networks and radio technologies. For the sake of clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

[0049] In the communication, the terminal device 120 is configured to estimate and report the CSI of the communication channel between the terminal device 120 and the network device 110. The CSI can be determined by the terminal device 120 using downlink reference signals transmitted by the network device 110.

[0050] Figure 2 is a schematic diagram illustrating a procedure 200 of subband indication transmission according to some embodiments of the present disclosure. The network device 110 determines 205 a plurality of subbands for the terminal device 120 to perform channel state estimation. The plurality of subbands determined by the network device 110 needs to be regularly distributed in the frequency domain. For example, the plurality of subbands are continuously distributed in the frequency domain or evenly spaced apart in the frequency domain.

[0051] With reference to Figure 3A and 3B , Figure 3A is shown a schematic diagram 300 illustrating a plurality of subbands 301-304 according to some embodiments of the present disclosure, Figure 3B is shown a schematic diagram 350 illustrating a plurality of subbands 311-313 according to some embodiments of the present disclosure. In Figure 3A the example, the four subbands 301-304 selected by the network device 110 are continuously distributed in the frequency domain. In Figure 3B the example, the three subbands 311-313 selected by the network device 120 are evenly spaced apart in the frequency domain with an offset 320.

[0052] The network device 110 transmits 210 a subband indication for the plurality of subbands to the terminal device 120 to enable channel state information estimation by the terminal device 120 for the plurality of subbands. The subband indication can be determined based on the configuration of the plurality of subbands.

[0053] The plurality of subbands can be indicated in various ways. The subband indication can comprise an indication of a starting subband and an indication of a number of subbands in the plurality of subbands. For example, the subband indication can comprise an index of the starting subband and an indication of a number or length of the plurality of subbands. Figure 3A For the example shown, the subband indication can comprise an index of the subband 301 and an indication of a number or length of the plurality of subbands 301-304. Alternatively or additionally, the subband indication can comprise an indication of a starting subband and an indication of an ending subband. For example, the subband indication can comprise an index of the subband 301 and an index of the subband 304. The index of the subband 301 and the index of the subband 304 can be indicated by a combined index number, which is two indices selected from the plurality of indices.

[0054] The subband indication can comprise an indication of a starting subband, an indication of a number of subbands in the plurality of subbands or a length of the plurality of subbands, and an indication of an offset between adjacent subbands in the plurality of subbands. For example, the subband indication can comprise an index of the starting subband, an indication of a number of subbands in the plurality of subbands (in this example, 3), and an indication of the offset 320. Alternatively or additionally, the subband indication can comprise an indication of a starting subband, an indication of an ending subband, and an indication of an offset between adjacent subbands in the plurality of subbands. For example, the subband indication can comprise an index of the subband 311, an index of the subband 313, and an indication of the offset 420. Figure 3B

[0055] The subband indication can comprise an indication of a position of the plurality of subbands in the wideband. For example, the subband indication can comprise a bit string with "1" only at adjacent positions or equidistantly spaced with a fixed offset, etc.

[0056] Upon receiving the subband indication for the plurality of subbands from the network device 110, the terminal device 120 determines 215 the plurality of subbands based on the subband indication. The terminal device 120 then performs 220 channel state estimation for the plurality of subbands. For example, the terminal device 120 can perform channel state estimation for the plurality of subbands 301-304; for example, the terminal device 120 can perform channel state estimation for the plurality of subbands 311-313. Figure 3A Figure 3B

[0057] Figure 4 ​​​is a schematic diagram illustrating a procedure 400 of CSI transmission according to some embodiments of the present disclosure. After performing channel estimation between the network device 110 and the terminal device 120 across a predetermined frequency range for multiple beams having different spatial directions, the terminal device 120 can determine CSI to be reported to the network device 110. In some embodiments, channel estimation can be performed on subbands indicated by the network device 110, as described above with reference to Figure 2 However, embodiments described with reference to Figure 4 are not limited thereto. The CSI report is to be transmitted using uplink resources as part of uplink control information (UCI), e.g., included in an uplink data channel such as a physical uplink shared channel (PUSCH). The UCI can also include other information having a higher priority than the CSI report. In this case, the terminal device 120 can need to determine whether the available uplink resources are large enough to carry the CSI. For example, the number of bits that can be carried in the available uplink resources can be less than the number of bits of the CSI report, or the actual coding rate for carrying the complete CSI report on the available uplink resources can be greater than a coding rate threshold. Thus, the complete CSI report cannot be transmitted on the available resources.

[0058] The terminal device 120 determines 405 a payload of CSI for at least one transmission layer. The CSI for the at least one transmission layer is indicated to be reported for communication between the terminal device 110 and the network device 120. In a MIMO scenario, the network device 110 can configure a maximum number of transmission layers for the terminal device 120 to report CSI for communication, and the terminal device 120 can indicate the actual number of transmission layers to the network device 110 as rank information in the CSI report. The actual number of transmission layers reported by the terminal device 120 can be equal to or less than the maximum number of transmission layers configured by the network device 110. For brevity, a transmission layer can also be referred to as a layer, e.g., layer 1, layer 2, layer 3, and layer 4.

[0059] In response to determining that the payload exceeds the capacity of the available uplink resources, the terminal device 120 discards 410 a portion of the channel state information. The discarded portion includes at least an indication specific to one of the at least one transmission layer. For example, if the terminal device 120 determines that the available resources of the UCI are insufficient to carry the CSI report or the actual coding rate is greater than a coding rate threshold, the terminal device 120 can discard at least a portion of the CSI.

[0060] The terminal device 120 transmits 415 the remaining part of the channel state information to the network device 110. The payload of the remaining part is equal to or less than the capacity of the available uplink resources. It should be noted that in some embodiments, the actual payload of the remaining part can be zero, which means that no CSI is reported to the network device 110. For example, the full CSI is discarded. Upon receiving the CSI from the terminal device 120, the network device 110 can determine a codeword from a CSI codebook (e.g., a Type II CSI codebook) to control the transmission with the terminal device 120, e.g., based on the received CSI.

[0061] How to discard at least part of the CSI will be explained in detail below. To better understand the example embodiments of the present disclosure, an enhanced Type II codebook is first described. A spatial frequency matrix W of layer r can be represented by the following equation (1):

[0062]

[0063] If R layers are indicated by the terminal device 120, equation (1) can be expressed as:

[0064]

[0065] where R can be equal to 1,..., R max and R max are configured by the network device 110. W1knows respectively include bases selected from a set of spatial domain (SD) bases and a set of frequency domain (FD) bases. The coefficient matrix has a dimension of 2L x M, where L and M are the number of selected SD bases and FD bases, respectively.

[0066] W1as layer-common can be expressed as:

[0067]

[0068] The selection of SD bases is common for any layer r. For example, the L SD bases can be selected from a set of N1N2 x 1 orthogonal discrete Fourier transform (DFT) vectors. Further, there can be O1O2 groups of DFT vectors, and a group is selected from all O1O2 groups using an oversampling factor.

[0069] W1as layer-specific can be expressed as:

[0070]

[0071] The selection of FD bases is specific to each layer r. For example, M rAn FD basis can be selected from N3x1 orthogonal DFT vectors, and the index k i is applicable for 1≤k i ≤N3, where i=0,...,M r -1.

[0072] The coefficient matrix can be expressed as:

[0073]

[0074] where E (r) represents a 2LM r bitmap of layer r, and indicates whether a pair of SD and FD bases has a gain or not; represents an amplitude of a gain of a pair of SD bases v l and FD bases . represents a phase of a gain of a pair of SD bases v l and FD bases . and represent two different polarizations. and are reference amplitudes of strongest coefficient indicators (SCIs) of two polarizations, respectively, and can be reported to the network device 110.

[0075] Table 1 shows exemplary parameters or indications determined by the terminal device 120 and to be reported to the network device 110. It should be noted that the parameters or indications shown in Table 1 and the division of the UCI into three parts are given for discussion purposes without any limitation. More or less parameters or indications can be included in the CSI report, and the UCI can be divided in any other suitable manner. For example, the UCI can be divided into two parts: Part 1 and Part 2.

[0076] Exemplary parameters to be included in the CSI report according to Table 1

[0077]

[0078]

[0079] In the example shown in Table 1, the UCI is divided into three parts: Part 1, Part 2A, and Part 2B. The UCI Part 1 includes overall or general parameters, such as the “RI” indication of the number of transmission layers to be reported. The parameter “NNZC” indicates the number of non-zero coefficients for a layer, such as the bitmap E (r)The number of "1"s. The number of non-zero coefficients in UCI part 1 for all reporting layers determines the payload size of the remaining UCI. In some embodiments, UCI part 1 can also include a parameter "Indication of size of intermediate set N'3" which will be described below with reference to Figure 7 - Figure 9 is described in detail.

[0080] In the example of Table 1, UCI part 2A includes layer-common parameters or indications, e.g. "SD base subset selection indicator", which indicates the SD base subset selection applied to all reporting layers. In some embodiments, UCI part 2A can also include a parameter "Indication of intermediate FD base set" which will be described below with reference to Figure 7 - Figure 9 is described in detail.

[0081] UCI part 2B includes layer-specific parameters or indications related to and as described above.

[0082] In some embodiments, the terminal device 120 can determine from the channel state information a set of layer-specific indications for at least one of the at least one transmission layer and discard the set of layer-specific indications. The set of layer-specific indications to be discarded can be determined in various ways.

[0083] In one embodiment, the terminal device 120 can discard the layer-specific indications for all of the at least one transmission layer, e.g. all parameters included in UCI part 2B as shown in Table 1. In such an embodiment, after discarding all layer-specific indications, if the available resources are still insufficient to transmit the remaining part of the CSI, the terminal device 120 can further discard the layer-common indications. For example, the parameters included in UCI part 2A as shown in Table 1 can be discarded. If the available resources are still not enough, the parameters included in UCI part 1 can also be discarded. Thus, in such an embodiment, different parts of the CSI are prioritized based on the location in the UCI.

[0084] The discarding of the CSI can be further refined. For example, different parts of the CSI can be prioritized based on at least one of different transmission layers, different groups of transmission layers and specific indications. In one embodiment, different parts of the CSI can be prioritized based on different transmission layers. With reference to Figure 5A , Figure 5A A schematic diagram 500 is shown, illustrating the discarding of the CSI according to some embodiments of the present disclosure. In the example shown, the indication groups 501-504 include layer-specific indications for layers 1, 2, 3 and 4, respectively. Figure 5A

[0085] ​For example, the priority of these instruction groups can be defined as: instruction group 501 > instruction group 502 > instruction group 503 > instruction group 504. Thus, the instructions in instruction group 504 will be discarded first, followed by those in instruction group 503, and so on. Referring to equation (2), this means that, with... and The relevant parameters can be discarded first, and then... and The relevant parameters.

[0086] In another embodiment, different parts of the CSI can be prioritized based on different transport layer groups. (See reference) Figure 5B , Figure 5B A schematic diagram 550 is shown, illustrating the discarding of CSI according to some embodiments of this disclosure. Figure 5B In the example shown, layers 1, 2, 3, and 4 are divided into two layer groups: layer group A and layer group B. Instruction group 511 includes layer-specific instructions for layer group A (i.e., layers 1 and 2 in this example), and instruction group 512 includes layer-specific instructions for layer group B (i.e., layers 3 and 4 in this example).

[0087] For example, the priority of these instruction groups can be defined as instruction group 511 > instruction group 512. Thus, the instructions in instruction group 512 will be discarded first, followed by those in instruction group 511. Referring to equation (2), this means that, with... and The relevant parameters can be discarded first, and then... and The relevant parameters.

[0088] In another embodiment, the priorities of the different indicators can be further refined. Referring to Table 1, for example, the parameters "LC coefficient: phase" and "LC coefficient: amplitude" can have the lowest priority, and the parameter "strongest coefficient indicator" can have a higher priority than the parameters "LC coefficient: phase" and "LC coefficient: amplitude". The parameter "RI+NNZC" can have the highest priority.

[0089] It should be understood that aspects of the above embodiments in which CSI is discarded based on priority can be combined. For example, the parameters "LC coefficient: phase" and "LC coefficient: amplitude" for layer 4 can be discarded first.

[0090] In some embodiments, the overhead for CSI transmission can be reduced by reporting fewer actual NNZC values ​​(the number of non-zero coefficients) in UCI Part 2 (which includes Parts 2A and 2B in the examples of Table 1) compared to those reported in UCI Part 1. For the purposes of discussion, K in this disclosure rto indicate the value of NNZC reported in UCI part 1 for layer r, and K" r to indicate the actual number of non-zero LC coefficients to be reported in UCI part 2, i.e., the number of pairs of amplitude indication and phase indication for the gain of a pair of SD and FD bases.

[0091] Reference is made to Figure 6 , Figure 6 A diagram 600 is shown, which illustrates the change of CSI according to some embodiments of the present disclosure. In such embodiments, the indication 601, i.e., the bitmap E (r) for each layer, can be changed, and some entries in the indications 602 and 603 can be dropped or discarded. That is, by changing some entries of the bitmap E (r) from “1” to “0”, the corresponding pair of amplitude indication and phase indication can be discarded and not reported to the network device 110, which would be reported to the network device 110 if the uplink resource capacity is sufficient.

[0092] In one embodiment, the terminal device 120 can discard at least one pair of LC coefficients for each of the transmission layers. For example, the terminal device 120 can determine a first number of non-zero coefficients for a first of the at least one transmission layer, the first number of non-zero coefficients indicating a number of pairs of amplitude indication and phase indication for the gain to be reported to the network device 110. For example, the first number of non-zero coefficients for layer 1 can be denoted as K

[0093] Next, the terminal device 120 can update the non-zero coefficient indication for the first transmission layer based on the first number of pairs of amplitude indication and phase indication, and the non-zero coefficient indication indicating the positions of the first number of pairs of amplitude indication and phase indication. For example, the terminal device 120 can update the bitmap (indication 601) for layer 1 according to the selected pairs of LC coefficients. The terminal device 120 can then discard at least one of the first plurality of pairs of amplitude indication and phase indication other than the first number of pairs of amplitude indication and phase indication. For example, the terminal device 120 can discard the other K1-K

[0094] The terminal device 120 can repeat the above procedure for each of the transmission layers, e.g., each of layers 1, 2, 3, and 4. The value of K r may be fixed, e.g., as a ratio of K r , such as Kr / 2. K" r The value of NNZC can alternatively be indicated by a higher layer. The ratio can be the same or different for different layers. In such embodiments, the size of the indication 601 (i.e. the bitmap for each layer) is unchanged, but the sum of the "1"s in the bitmap for each layer indicating the actual number of non-zero coefficients reported is less than the value of NNZC in UCI part 1. The size of the indications 602 and 603 is reduced, thereby reducing the payload of UCI part 2.

[0095] For example, in UCI part 1, for layer 1, the value of NNZC is 6, where L = 2, M1 = 4. Before dropping, in UCI part 2, the bitmap for layer 1 can be [10010100 10000101]. After dropping, in UCI part 2, the bitmap for layer 1 can be [10000100 10000100], where only 4 non-zero coefficients are reported instead of 6. The bit values changed from 1 to 0 correspond to the non-zero coefficients that are dropped.

[0096] In such embodiments, K" r pairs of LC coefficients can be determined based on amplitude values of K r pairs of LC coefficients. The terminal device 120 can determine an amplitude value for each of the first plurality of amplitude and phase indication pairs (e.g. K r pairs of LC coefficients) and select a first number of amplitude and phase indication pairs (e.g. K" r pairs of LC coefficients) based on the determined amplitude values.

[0097] For example, K" r pairs of LC coefficients can be selected based on the following equation:

[0098]

[0099] where H r is the channel estimation result for layer r and P r is a scaling factor. The equation is used to minimize the MMSE of the CSI in layer r by selecting to drop indications related to non-zero coefficients with smaller amplitudes.

[0100] The amplitudes are ordered per layer according to the amplitudes and the first maximum K" r amplitudes and their phases are reported and the remaining amplitudes and their phases are dropped.

[0101] In another embodiment, the terminal device 120 can drop at least one pair of LC coefficients for a group of transmission layers, meaning that K" S =∑ r∈S K" r<K s =∑ r∈S K r , where the set of S transmission layers is configured by a higher layer. For example, the terminal device 120 can determine a second number of non-zero coefficients (K S ) for the set of S transmission layers, where S = {1,..., R}. The second number of non-zero coefficients (K S ) indicates a number of pairs of amplitude indications and phase indications for the gain to be reported to the network device 110. The terminal device 120 can then select a second number of pairs of amplitude indications and phase indications (e.g., K S ) LC coefficient pairs) for the set of S transmission layers from the second plurality of pairs of amplitude indications and phase indications (e.g., K S ) LC coefficient pairs). In some embodiments, the set of S transmission layers can include all transmission layers. In this case, K S = K.

[0102] Next, the terminal device 120 can update the non-zero coefficient indication for each of the at least one transmission layer based on the second number of pairs of amplitude indications and phase indications, and the non-zero coefficient indication indicates a position of the selected pair of amplitude indication and phase indication for the respective transmission layer. For example, a bitmap (indication 601) for layer r can be set accordingly to indicate the K r ) LC coefficient pairs.

[0103] The terminal device 120 can then discard at least one pair of amplitude indication and phase indication of the second plurality of pairs of amplitude indications and phase indications other than the second number of pairs of amplitude indications and phase indications. For example, the terminal device 120 can discard the other (K S -K S ) LC coefficient pairs.

[0104] In such embodiments, the K S ) LC coefficient pairs can be determined based on amplitude values of the K S ) LC coefficient pairs for the set of S layers. The terminal device 120 can determine an amplitude value for each of the second plurality of pairs of amplitude indications and phase indications (e.g., K S ) LC coefficient pairs), and select the second number of pairs of amplitude indications and phase indications (e.g., K S ) LC coefficient pairs) based on the determined amplitude values.

[0105] For example, when S indicates all layers (where K S = K), the K

[0106]

[0107] This equation is used to minimize the MMSE of CSI distortion in all layers by selectively discarding indicators associated with non-zero coefficients with smaller amplitudes.

[0108] The amplitudes are sorted across all layers, and the first largest K″ amplitudes and their phases are reported, while the remaining amplitudes and their phases are discarded.

[0109] K″ S The value can be fixed. For example, K″ S The value can be determined as K S The ratio, such as K S / 2. K″ S The value or ratio can alternatively be indicated by a higher layer. In such an embodiment, the size of the indication (i.e., for each layer's bitmap) remains unchanged, but the sum of the "1s" in each layer's bitmap is less than NNZC in UCI section 1. Reducing the size of indications 602 and 603 reduces the payload of UCI section 2.

[0110] In another embodiment, terminal device 120 may discard an indication associated with a polarization to reduce the size of UCI portion 2. For one or each of at least one transport layer, terminal device 120 may determine the polarization with the lower amplitude from two polarizations for the transport layer in at least one transport layer. The amplitude of the polarization may be based on, for example, the parameter “SCI” shown in Table 1 or... and The reference value is used to determine this. Terminal device 120 can then select a third number of amplitude and phase indicator pairs corresponding to the selected polarization from a third plurality of amplitude and phase indicator pairs for the second transmission layer. For example, terminal device 120 can select all LC coefficient pairs associated with the stronger polarization of the two polarizations.

[0111] Next, terminal device 120 can update the non-zero coefficient indication for the transport layer based on a third number of amplitude and phase indication pairs. The non-zero coefficient indication indicates the position of the third number of amplitude and phase indication pairs. For example, terminal device 120 can update indication 601, i.e., for a bitmap of at least one or each transport layer. Then, terminal device 120 can discard at least one amplitude and phase indication pair other than the third number of amplitude and phase indication pairs. For example, terminal device 120 can discard all LC coefficient pairs associated with the weaker polarization of two polarizations. In this case, the value of the third number is determined based on the number of non-zero coefficients associated with the weaker polarization.

[0112] The terminal device 120 can perform the above-described polarization-based dropping procedure on each or some of the at least one transport layer. In such embodiments, the UCI part 1 is not affected and the size of the indication 601-603 is reduced. The size of the bitmap for each layer is changed from 2LM r to LM r , thereby reducing the size of the UCI part 2A. Some entries in the indication 602 and 603 related to weaker polarizations are dropped, thereby resulting in a reduction of the size of the UCI part 2B. As an example, in the UCI part 1, the reported value of NNZC for layer 1 is 6, with L = 2, M1= 4. After dropping, in the UCI part 2, the bitmap for layer 1 is [10000100], which only indicates the stronger polarizations indicated by the SCI indication. Thus, in such embodiments, the payload of both the UCI part 2A and part 2B can be reduced.

[0113] In yet another embodiment, the terminal device 120 can drop the indication by assuming that the CSI configuration parameter “up” for the UCI part 2 is changed to “L / 2” or the CSI configuration parameter “M r ” is changed to “M r / 2”. The terminal device 120 can then report the UCI part 2 based on the reduced CSI configuration parameters instead of the original CSI configuration parameters.

[0114] It should be noted that the network device 110 can also be aware of the dropping rules described with respect to any of the embodiments, such that upon receiving the CSI report, the network device 110 can determine the codeword from the Type II CSI codebook.

[0115] To reduce the overhead for CSI transmission, a two-step FD basis selection can be implemented to compress the CSI. In this two-step FD basis selection, an intermediate set of FD bases can be first determined, and then the selection of the FD bases for each layer can be indicated based on the intermediate set of FD bases. Such embodiments will be described below with reference to Figure 7 FIG. 9.

[0116] Figure 7 is a schematic diagram illustrating a process 700 of CSI compression according to some embodiments of the present disclosure. The terminal device 120 determines 705 an ordered subset of FD bases for at least one transport layer. The at least one transport layer is reported by the terminal device 120 to the network device 110 for communication. The ordered subset of FD bases is selected from an ordered set of FD bases, e.g., DFT vectors as described above.

[0117] Terminal device 120 determines an intermediate set of FD bases 710 through a shift operation based on an ordered subset of FD bases. The intermediate set of FD bases may, for example, refer to the "Intermediate FD Base Set" shown in Table 1. In this document, the number of FD bases in the intermediate set can be represented by N3′. Terminal device 120 sends at least a 715 number indication to network device 110 as part of channel state information, and this number indication indicates the number of FD bases in the intermediate set. For example, terminal device 120 sends at least a number indication to network device 110, such as the "Intermediate Set Size Indicator N3′" indicated in Table 1 of UCI Part 1. The maximum possible value of N3′ can be fixed or configured to N by higher layers. The default value of N can be N3. To save overhead, the bit width used to indicate the "Intermediate Set Size Indicator N3′" in UCI Part 1 can be determined as follows: Where M r This is the number of FD base subsets configured by network device 110 for selecting layer r. For example, it can be configured to such that...

[0118] The shift operation is now described in detail. As mentioned above, the Enhanced Type II CSI report has for layer r... In the form of a vector representing the selected subset of the FD basis for layer r (e.g., the ordered subset of the FD basis mentioned above). (index sorted as) It can be multiplied by a parameter k. * The rotation matrix R ∈ {1, ..., N3}

[0119]

[0120] index set Sort in ascending order in This means that the ordered set of indexes for the selected FD basis subset via k * The shift is caused by the N3 module shifting to

[0121] Then, the new FD base subset is obtained by using the original... The N3 modulus shift is expressed as

[0122]

[0123] Where matrix P is of size M r *M r The appropriate unique permutation matrix.

[0124] corresponding It is also shifted by the permutation matrix P.

[0125]

[0126] Upon receiving the reported UCI with the shift operation, the network device 120 can reconstruct the CSI report by using the shift and the reported and as follows:

[0127]

[0128] This means that the PMI of the CSI report is different from the original PMI, which is only shifted by one phase factor, and the network device 110 does not need to know the N3mod shift.

[0129] When more than one transmission layer is configured for communication, the terminal device 120 can perform the same shift operation with respect to each layer. Alternatively, the terminal device 120 can independently perform the shift operation with respect to the layers.

[0130] In some embodiments, the terminal device 120 can determine a first ordered subset of FD bases for a first transmission layer and a second ordered subset of FD bases for a second transmission layer, and the first transmission layer is different from the second transmission layer. Then, the terminal device 120 can determine a union set of FD bases based on a union of the first ordered subset of FD bases and the second ordered subset of FD bases, and perform a shift operation on the FD bases in the union set of FD bases to obtain an intermediate set of FD bases.

[0131] Reference is made to Figure 8 to describe such examples. Figure 8 A diagram 800 is shown, which illustrates FD base selection according to some embodiments of the present disclosure. For illustration purposes only and without any limitation, the selection of FD bases is shown in a bitmap fashion. In Figure 8 In the shown example, bitmaps 801-804 represent the subset of FD bases selected for layers 1-4, respectively. Bitmap 805 represents a union set of FD bases, which covers the union of the subset of bases for each of layers 1-4. For bitmap 805, the starting point is at M initial and the size is N3'. The FD bases in this union set are given by the index mod(M initial +n, N3) with n = 0, 1,.., N3'- 1. This union set as illustrated by bitmap 805 can be further shifted to simplify the indication of the FD bases.

[0132] For example, the terminal device 120 can shift the union set of FD bases by M initial to obtain an intermediate set of FD bases. As Figure 8In the illustrated example, bitmap 805 is shifted by 7 to obtain bitmap 806, which represents an intermediate set of FD bases. Such an intermediate set of FD bases can be considered as a window. Due to the shifting operation, the terminal device 120 can update the corresponding indication accordingly, e.g., the indication associated with and is updated to the indication associated with and .

[0133] If N3' is neither fixed nor configured by higher layer, the terminal device 120 can report the size N3' of the intermediate set to the network device 110, e.g., in UCI part 1. The terminal device 120 can further report (e.g., in UCI part 2) a N3' bit bitmap or bit indicator to indicate the FD bases for each layer. In such embodiments, by the same shifting operation on each subset of FD bases for a layer, it can be ensured that the first base in the ordered set of FD bases, or the starting index M initial of the window of the intermediate set is fixed. Thus, the indication for the intermediate set can be omitted in UCI part 2. For example, the parameter "indication of intermediate FD base set" shown in Table 1 can be omitted.

[0134] As mentioned above, the shifting operation can be performed independently with respect to layers. In some embodiments, the terminal device 120 can determine a first ordered subset of FD bases for a first transmission layer and a second ordered subset of FD bases for a second transmission layer, and the first transmission layer is different from the second transmission layer. The terminal device 120 can then perform the shifting operation independently on the FD bases in the first ordered subset of FD bases and the second ordered subset of FD bases to obtain a first shifted version of the first ordered subset of FD bases and a second shifted version of the second ordered subset of FD bases. Next, the terminal device 120 can determine the intermediate set of FD bases based on a union of the first shifted version and the second shifted version.

[0135] Reference is made to Figure 9A and Figure 9B to describe examples. Figure 9A A diagram 900 is shown, which illustrates FD base selection according to some embodiments of the present disclosure. Figure 9A An example of a window-based intermediate set is shown. Bitmap 901 represents a subset of FD bases selected for layer 1 without shifting, and bitmap 902 represents a subset of FD bases selected for layer 2 without shifting. Bitmap 903 represents a union set of FD bases based on the subset of FD bases for layer 1 and the subset of FD bases for layer 2 without shifting.

[0136] Bitmap 904 represents a shifted version (shifted by 7) of the subset of FD bases for layer 1, and bitmap 905 represents a shifted version (shifted by 1) of the subset of FD bases for layer 2. Bitmap 906 represents an intermediate set determined by terminal device 120 based on independent shifting operations on the subset of FD bases for different layers (in this example, layers 1 and 2). As can be seen in bitmap 906, the resulting window length to be reported is significantly reduced compared to the window length in bitmap 903. In another example, the bitmaps for each layer can first be shifted to the dictionary maximum (e.g., if there are two layers and N3= 4, then “0100” and “0011” are shifted to “1000” and “1100”). The value of N3-N3’ in the intermediate set based on the window in case of reporting N3’ can correspond to the minimum number of consecutive zeros in the least significant bits of all layers, i.e., N3-N3’ = 2, so that N3’ = 2.

[0137] Figure 9B A diagram 910 is shown, which illustrates FD base selection according to some embodiments of the present disclosure. Figure 9B An example of an intermediate set based on the combined index is shown. Bitmap 911 represents the subset of FD bases selected for layer 1 without shifting, and bitmap 912 represents the subset of FD bases selected for layer 2 without shifting. Bitmap 913 represents a union set of FD bases without shifting based on the subset of FD bases for layer 1 and the subset of FD bases for layer 2.

[0138] Bitmap 914 represents a shifted version (shifted by 7) of the subset of FD bases for layer 1, and bitmap 915 represents a shifted version (shifted by 2) of the subset of FD bases for layer 2. Bitmap 916 represents an intermediate set determined by terminal device 120 based on independent shifting operations on the subset of FD bases for different layers (in this example, layers 1 and 2). As can be seen in bitmap 916, the resulting size of the intermediate set to be reported is significantly reduced compared to the intermediate set in bitmap 913. The modulo shifting plays an important role in reducing the intermediate set size.

[0139] In such embodiments, the independent shifting operation on the subset of FD bases for each layer aims to find the maximum number of zeros at the same position in the bitmap (N3-N3’), and the first FD base in the set of FD bases (e.g., the first vector in the DFT matrix) is valid, or in other words, selected by at least one transmission layer.

[0140] In such embodiments, the terminal device 120 can report a size of N3' (N3' ≤ N3), e.g., in UCI part 1. The terminal device 120 can also report an indication of the intermediate set (also referred to as a set indication). By the modulo shift operation described above, the first FD basis can always be selected by default, and thus the size of the set indication in this case is This means that the remaining N'3-1 bases of the intermediate set are selected from the remaining N3-1 bases. This further reduces the overhead of the CSI transmission.

[0141] The terminal device 120 can also report (e.g., in UCI part 2) a N3' bit bitmap or bit indicators to indicate the FD basis for each layer.

[0142] Figure 10 A flowchart of an example method 1000 is shown in accordance with some embodiments of the present disclosure. The method 1000 can be implemented, for example, Figure 1 at the terminal device 120 shown. It will be understood that the method 1000 can include additional blocks not shown and / or some of the blocks shown can be omitted, and the scope of the disclosure is not limited in this regard. For discussion purposes, the method 1000 will be described with reference to the terminal device 120 shown in FIG. 1. Figure 1 The method 1000 is described.

[0143] At block 1010, the terminal device 120 determines a payload of channel state information for at least one transmission layer. The at least one transmission layer is configured for communication between the terminal device 120 and the network device 110.

[0144] At block 1020, the terminal device 120 determines whether the payload exceeds a capacity of available uplink resources. If the terminal device 120 determines that the payload exceeds the capacity of available uplink resources, the process proceeds to block 1030.

[0145] At block 1030, the terminal device 120 discards a portion of the channel state information. The portion discarded includes at least an indication specific to one of the at least one transmission layer.

[0146] In some embodiments, discarding the portion of the channel state information includes determining, from the channel state information, a set of layer-specific indications for at least one of the at least one transmission layer, and discarding the set of layer-specific indications.

[0147] In some embodiments, the set includes layer-specific indications for all of the at least one transmission layer, and the method further includes determining, from the channel state information, a set of layer-common indications for all of the at least one transmission layer, and discarding the set of layer-common indications.

[0148] In some embodiments, discarding the portion of the channel state information includes determining a first number of non-zero coefficients for a first transmission layer of the at least one transmission layer, the first number of non-zero coefficients indicating a number of pairs of amplitude indications and phase indications for a gain to be reported to the network device, selecting the first number of pairs of amplitude indications and phase indications from the first plurality of pairs of amplitude indications and phase indications for the first transmission layer, updating a non-zero coefficient indication for the first transmission layer based on the first number of pairs of amplitude indications and phase indications, the non-zero coefficient indication indicating locations of the first number of pairs of amplitude indications and phase indications, and discarding at least one pair of amplitude indications and phase indications of the first plurality of pairs of amplitude indications and phase indications other than the first number of pairs of amplitude indications and phase indications.

[0149] In some embodiments, selecting the first number of pairs of amplitude indications and phase indications includes determining an amplitude value for each pair of amplitude indications and phase indications of the first plurality of pairs of amplitude indications and phase indications, and selecting the first number of pairs of amplitude indications and phase indications based on the determined amplitude values.

[0150] In some embodiments, discarding the portion of the channel state information includes determining a second number of non-zero coefficients for all of the transmission layers of the at least one transmission layer, the second number of non-zero coefficients indicating a number of pairs of amplitude indications and phase indications for a gain to be reported to the network device, selecting the second number of pairs of amplitude indications and phase indications from a second plurality of pairs of amplitude indications and phase indications for all of the transmission layers of the at least one transmission layer, updating a non-zero coefficient indication for each of the transmission layers of the at least one transmission layer based on the second number of pairs of amplitude indications and phase indications, the non-zero coefficient indication indicating locations of the selected pairs of amplitude indications and phase indications for the respective transmission layer, and discarding at least one pair of amplitude indications and phase indications of the second plurality of pairs of amplitude indications and phase indications other than the second number of pairs of amplitude indications and phase indications.

[0151] In some embodiments, selecting the second number of pairs of amplitude indications and phase indications includes determining an amplitude value for each pair of amplitude indications and phase indications of the second plurality of pairs of amplitude indications and phase indications, and selecting the second number of pairs of amplitude indications and phase indications based on the determined amplitude values.

[0152] In some embodiments, discarding the portion of the channel state information comprises: determining, for a second transport layer of the at least one transport layer, a polarization having a lower amplitude from the two polarizations; selecting, from the third plurality of amplitude and phase indication pairs for the second transport layer, a third number of amplitude and phase indication pairs corresponding to the selected polarization; updating, based on the third number of amplitude and phase indication pairs, a non-zero coefficient indication for the second transport layer, the non-zero coefficient indication indicating positions of the third number of amplitude and phase indication pairs; and discarding at least one amplitude and phase indication pair of the third plurality of amplitude and phase indication pairs other than the third number of amplitude and phase indication pairs.

[0153] At block 1040, the terminal device 120 transmits the remaining portion of the channel state information to the network device 110.

[0154] Figure 11 A flowchart of an example method 1100 is shown, in accordance with some embodiments of the present disclosure. The method 1100 can be implemented, for example, at the terminal device 120 shown. It should be understood that the method 1000 can include additional blocks not shown and / or some of the blocks shown can be omitted, and the scope of the disclosure is not limited in this regard. For discussion purposes, the method 1100 will be described with reference to the terminal device 120 shown in FIG. 1. Figure 1 It should be understood that the method 1000 can include additional blocks not shown and / or some of the blocks shown can be omitted, and the scope of the disclosure is not limited in this regard. For discussion purposes, the method 1000 will be described with reference to the terminal device 120 shown in FIG. 1. Figure 1 The method 1100 is described with reference to the terminal device 120 shown.

[0155] At block 1110, the terminal device 120 determines an ordered subset of frequency domain (FD) bases for the at least one transport layer. The at least one transport layer is configured for communication between the terminal device 120 and the network device 110, and the ordered subset of FD bases is selected from an ordered set of FD bases.

[0156] At block 1120, the terminal device 120 determines, based on the ordered subset of FD bases, an intermediate set of FD bases by a shift operation.

[0157] In some embodiments, determining the ordered subset of FD bases for the at least one transport layer comprises: determining a first ordered subset of FD bases for a first transport layer and a second ordered subset of FD bases for a second transport layer, the first transport layer being different from the second transport layer; and determining the intermediate set of FD bases comprises: determining a union set of FD bases based on a union of the first ordered subset of FD bases and the second ordered subset of FD bases; and performing the shift operation on the FD bases in the union set of FD bases to obtain the intermediate set of FD bases.

[0158] In some embodiments, determining the ordered subset of FD bases for the at least one transmission layer comprises determining a first ordered subset of FD bases for a first transmission layer and a second ordered subset of FD bases for a second transmission layer, the first transmission layer being different from the second transmission layer; and determining the intermediate set of FD bases comprises performing a shift operation independently on the FD bases in the first ordered subset of FD bases and the second ordered subset of FD bases to obtain a first shifted version of the first ordered subset of FD bases and a second shifted version of the second ordered subset of FD bases; and determining the intermediate set of FD bases based on a union of the first shifted version and the second shifted version.

[0159] In some embodiments, the method further comprises determining a set indication for indicating the set of FD bases in the intermediate set of FD bases; and transmitting the set indication to the network device as part of the channel state information.

[0160] At block 1130, the terminal device 120 transmits at least the number indication to the network device 110 as part of the channel state information. The number indication indicates the number of FD bases in the intermediate set.

[0161] In some embodiments, the method further comprises determining a selection indication for the at least one transmission layer based on the mapping between the ordered subset of FD bases and the intermediate set of FD bases, the selection indication indicating a selection of FD bases in the intermediate set; and transmitting the selection indication to the network device as part of the channel state information.

[0162] Figure 12 A flow chart illustrating an example method 1200 according to some embodiments of the present disclosure is shown. The method 1200 can be implemented, for example, at the network device 110 shown. Figure 1 It should be understood that the method 1200 can include additional blocks not shown and / or some of the blocks shown can be omitted, and the scope of the disclosure is not limited in this regard. For discussion purposes, the method 1200 will be described with reference to the network device 110. Figure 1 The method 1200 is described.

[0163] At block 1210, the network device 110 determines a plurality of subbands for the terminal device 120. The plurality of subbands are distributed consecutively in the frequency domain or are uniformly spaced apart in the frequency domain.

[0164] At block 1220, the network device 110 transmits a subband indication for the plurality of subbands to the terminal device 120 to enable channel state estimation by the terminal device on the plurality of subbands.

[0165] In some embodiments, transmitting the subband indication for the plurality of subbands comprises transmitting at least one of: an indication of a starting subband and an indication of a number of subbands in the plurality of subbands; an indication of the starting subband and an indication of an ending subband; an indication of the starting subband, an indication of a number of subbands in the plurality of subbands, and an indication of an offset between adjacent subbands in the plurality of subbands; an indication of the starting subband, an indication of the ending subband, and an indication of the offset between adjacent subbands in the plurality of subbands; and an indication of a location of the plurality of subbands in a wideband.

[0166] Figure 13 A flowchart of an example method 1300 is shown in accordance with some embodiments of the present disclosure. The method 1300 can be implemented, for example, at a terminal device 120 as shown. It should be understood that the method 1300 can include additional blocks not shown and / or can omit some of the blocks shown, and the scope of the present disclosure is not limited in this regard. For discussion purposes, the method 1300 will be described with reference to the terminal device 120 shown in FIG. 1. Figure 1 Figure 1 The method 1300 is described with reference to the terminal device 120 shown in FIG. 1.

[0167] At block 1310, the terminal device 120 receives a subband indication for a plurality of subbands from the network device 110. The plurality of subbands are either continuously distributed in a frequency domain or uniformly spaced in the frequency domain.

[0168] At block 1320, the terminal device 120 determines the plurality of subbands based on the subband indication. At block 1330, the terminal device 120 performs channel state estimation on the plurality of subbands.

[0169] In some embodiments, receiving the subband indication for the plurality of subbands comprises receiving at least one of: an indication of a starting subband and an indication of a number of subbands in the plurality of subbands; an indication of the starting subband and an indication of an ending subband; an indication of the starting subband, an indication of a number of subbands in the plurality of subbands, and an indication of an offset between adjacent subbands in the plurality of subbands; an indication of the starting subband, an indication of the ending subband, and an indication of the offset between adjacent subbands in the plurality of subbands; and an indication of a location of the plurality of subbands in a wideband.

[0170] Figure 14 is a simplified block diagram of a device 1400 suitable for implementing embodiments of the present disclosure. The device 1400 can be considered as another example implementation of the network device 110 or the terminal device 120 as shown in FIG. 1. Accordingly, the device 1400 can be implemented at the network device 110 or the terminal device 120, or as at least a portion of the network device 110 or the terminal device 120. Figure 1

[0171] ​​As shown, the device 1400 includes a processor 1410, a memory 1420 coupled to the processor 1410, a suitable transmitter (TX) and receiver (RX) 1440 coupled to the processor 1410, and a communication interface coupled to the TX / RX 1440. The memory 1410 stores at least a portion of a program 1430. The TX / RX 1440 is for bidirectional communication. The TX / RX 1440 has at least one antenna to facilitate communication, although in practice the access node mentioned in this application can have several antennas. The communication interface can represent any interface needed to communicate with other network elements, such as an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a mobility management entity (MME) / serving gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a relay node (RN), or a Uu interface for communication between an eNB and a terminal device.

[0172] The program 1430 is assumed to include program instructions that, when executed by the associated processor 1410, enable the device 1400 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to the Figures 10-13 Embodiments herein can be implemented through computer software executable by the processor 1410 of the device 1400, or by hardware, or by a combination of software and hardware. The processor 1410 can be configured to implement various embodiments of the present disclosure. Further, the processor 1410 and the memory 1410 can form a processing arrangement 1450 suitable for implementing various embodiments of the present disclosure.

[0173] The memory 1410 can be of any type suitable to the local technical network and can use any suitable data storage technology, as non-limiting examples such as non-transitory computer-readable storage mediums, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. While only one memory 1410 is shown in the device 1400, there can be several physically distinct memory modules in the device 1400. The processor 1410 can be of any type suitable to the local technical network, and can include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples. The device 1400 can have multiple processors such as a special purpose integrated circuit chip that is time-synchronized with a clock that synchronizes the main processor.

[0174] In general, the various embodiments of the disclosure can be implemented in hardware or special-purpose circuits, software, logic or any combination thereof. Some aspects can be implemented in hardware, while other aspects can be implemented in firmware or software which can be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein can be implemented in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controler or other computing devices, or some combination thereof.

[0175] The present disclosure also provides at least one computer program product which is tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, executed by devices on a target real or virtual processor to perform the processes or methods described above with respect to any of FIGS. 3, 5, Figure 6 、 Figure 8 、 Figure 12 and Figure 13 Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules can be combined or split between program modules as desired in various embodiments. Machine executable instructions for program modules can be executed within a local or distributed device. In a distributed device, program modules can be located in local and remote memory storage devices.

[0176] Program code utilized by or to implement the present disclosure can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the code, which executes via the processor or controller, produces a result or implements the steps specified in the flowcharts and / or diagrams. The program code can execute entirely on a machine, partly on a machine, as a stand-alone software package, partly on a machine and partly on a remote machine or entirely on a remote machine or server.

[0177] The above program code can be embodied on a machine-readable medium, which can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0178] Moreover, while operations can be depicted in the drawings in a particular, serial order, this should not be understood as requiring or implying that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Likewise, while several specific implementation details have been discussed, these should not be construed as limiting the scope of the disclosure, but merely as describing examples of certain implementations. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments or in any suitable sub-combination.

[0179] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject of the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as example forms of implementing the claims.

Claims

1. A method for communication, comprising: determining a payload of channel state information for at least one transmission layer, the at least one transmission layer being used for communication between a terminal device and a network device; in response to determining that the payload exceeds a capacity of available uplink resources, discarding a portion of the channel state information, the discarded portion comprising at least an indication specific to one of the at least one transmission layer; and transmitting a remaining portion of the channel state information to the network device, wherein discarding the portion of the channel state information comprises: determining a second number of non-zero coefficients for a set of transmission layers of the at least one transmission layer, the second number of non-zero coefficients indicating a number of pairs of amplitude and phase indications for gain to be reported to the network device; selecting the second number of pairs of amplitude and phase indications from a second plurality of pairs of amplitude and phase indications for all of the at least one transmission layer; updating a non-zero coefficient indication for each of the at least one transmission layer based on the second number of pairs of amplitude and phase indications, the non-zero coefficient indication indicating a position of the selected pair of amplitude and phase indications for the respective transmission layer; and discarding at least one pair of amplitude and phase indications of the second plurality of pairs of amplitude and phase indications other than the second number of pairs of amplitude and phase indications.

2. The method of claim 1, wherein discarding the portion of the channel state information comprises: determining a set of layer-specific indications for at least one of the at least one transmission layer from the channel state information; and discarding the set of layer-specific indications.

3. The method of claim 1, wherein discarding the portion of the channel state information comprises: determining a first number of non-zero coefficients for a first transmission layer of the at least one transmission layer, the first number of non-zero coefficients indicating a number of pairs of amplitude and phase indications for gain to be reported to the network device; selecting the first number of pairs of amplitude and phase indications from a first plurality of pairs of amplitude and phase indications for the first transmission layer; updating a non-zero coefficient indication for the first transmission layer based on the first number of pairs of amplitude and phase indications, the non-zero coefficient indication indicating a position of the first number of pairs of amplitude and phase indications; and discarding at least one pair of amplitude and phase indications of the first plurality of pairs of amplitude and phase indications other than the first number of pairs of amplitude and phase indications.

4. The method of claim 3, wherein selecting the first number of pairs of amplitude and phase indications comprises: determining an amplitude value for each pair of amplitude and phase indications of the first plurality of pairs of amplitude and phase indications; and selecting the first number of pairs of amplitude and phase indications based on the determined amplitude values.

5. The method of claim 1, wherein selecting the second number of pairs of amplitude and phase indications comprises: ​ ​ determining an amplitude value for each amplitude and phase indication pair of the second plurality of amplitude and phase indication pairs; and selecting the second number of amplitude and phase indication pairs based on the determined amplitude values.

6. The method of claim 1, wherein discarding the portion of the channel state information comprises: determining, for a second transmission layer of the at least one transmission layer, a polarization having a lower amplitude from two polarizations; from a third plurality of amplitude and phase indication pairs for the second transmission layer, selecting a third number of amplitude and phase indication pairs corresponding to the selected polarization; updating a non-zero coefficient indication for the second transmission layer based on the third number of amplitude and phase indication pairs, the non-zero coefficient indication indicating locations of the third number of amplitude and phase indication pairs; and discarding at least one amplitude and phase indication pair of the third plurality of amplitude and phase indication pairs other than the third number of amplitude and phase indication pairs.

7. An apparatus comprising: a processor; and a memory coupled to the processor and storing instructions thereon that, when executed by the processor, cause the apparatus to perform the method of any of claims 1-6.

8. A computer-readable medium having stored thereon instructions that, when executed on at least one processor, cause the at least one processor to perform the method of any of claims 1-6. ​

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