Apparatus and method for efficient communication in cellular communication network

Abstract

A user equipment (UE) (110) for communicating with a base station (130). The UE (110) comprises: a communication interface (113) configured to receive one or more pilot signals from the base station (130); a processing circuit (111) configured to estimate one or more current channel state information (CSI) values based on the one or more pilot signals from the base station (130). The processing circuitry (111) is further configured to quantize the one or more current CSI values to obtain one or more current quantized CSI values, and to encode the one or more current quantized CSI values based on a cell-specific encoding scheme to obtain one or more current encoded quantized CSI values. The cell-specific coding scheme defines a mapping from a plurality of possible quantized CSI values to a plurality of bit sequences having different numbers of bits.

Description

Technical Field

[0001] The present invention relates to communications in a cellular communication network. More specifically, the present invention relates to an apparatus and method for channel state information (CSI) feedback for efficient communications in a cellular communication network, particularly a 5G cellular communication network. Background Art

[0002] In cellular communication networks, channel state information (CSI) for the channel between a next-generation base station (gNB) node (i.e., a base station) and user equipment (UE) can be crucial for appropriate resource allocation. The base station may particularly need to know the CSI for the downlink channel. For example, when operating in frequency division duplexing (FDD) mode, the uplink and downlink channels use different frequency bands, so this CSI is not immediately available. Furthermore, when operating at high frequencies (e.g., millimeter wave) and equipped with multiple antennas, the gNB may need to acquire CSI for different beams detected by the gNB (i.e., for different spatial (angular) directions of downlink transmission). To this end, the 3GPP standard provides a scheme for an initial coarse estimate of the downlink CSI and subsequent refinement. According to the 3GPP standard, the gNB can transmit a known pilot signal, the Channel State Information Reference Signal (CSI-RS), to the UE. The UE then estimates the CSI and feeds back a quantized version of the CSI to the gNB for optimal communication on the downlink channel. Summary of the Invention

[0003] An object of the present invention is to provide an apparatus and method for CSI feedback for more efficient communication in a cellular communication network.

[0004] The aforementioned and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the drawings.

[0005] According to a first aspect, a user equipment (UE) is provided for communicating with a base station within a coverage area (i.e., a cell of a base station of a cellular communication network (e.g., a 5G communication network)). The UE comprises: a communication interface configured to receive one or more pilot signals from the base station; and processing circuitry configured to estimate one or more current channel state information (CSI) values based on the one or more pilot signals from the base station. The processing circuitry is further configured to: quantize the one or more current CSI values to obtain one or more current quantized CSI values, and encode the one or more current quantized CSI values based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values. The cell-specific coding scheme defines a mapping from multiple possible quantized CSI values to multiple bit sequences with different numbers of bits, which can reduce the number of bits required to represent the CSI, thereby reducing communication overhead.

[0006] In another possible implementation form of the first aspect, the communication interface is further configured to send the one or more current coded quantized CSI values to the base station.

[0007] In another possible implementation form of the first aspect, the mapping defined by the cell-specific coding scheme is configured to map the multiple possible quantized CSI values to the multiple bit sequences with different numbers of bits according to the corresponding occurrence frequency of each possible quantized CSI value in the multiple possible quantized CSI values.

[0008] In another possible implementation form of the first aspect, the mapping defined by the cell-specific coding scheme is configured to map the possible quantized CSI value with the highest frequency of occurrence among the multiple possible quantized CSI values to a bit sequence with the smallest number of bits among the multiple bit sequences.

[0009] In another possible implementation form of the first aspect, the cell-specific coding scheme is defined by one or more coding codebooks.

[0010] In another possible implementation form of the first aspect, the communication interface is configured to receive the one or more encoding codebooks from the base station and / or enable the processing circuit of the UE to generate or retrieve information of the one or more encoding codebooks.

[0011] In another possible implementation form of the first aspect, the communication interface is further configured to receive one or more quantization codebooks from the base station and / or enable the processing circuit of the UE to generate or retrieve information of the one or more quantization codebooks. The processing circuit may be configured to quantize the one or more current CSI values based on the one or more quantization codebooks to obtain the one or more current quantized CSI values.

[0012] In another possible implementation form of the first aspect, the one or more current CSI values include multiple current signal to interference plus noise ratio (SINR) values, and the one or more quantization codebooks include a first quantization codebook for quantizing peak values of the multiple current SINR values and a second quantization codebook for quantizing one or more differences in the multiple current SINR values relative to the peak values.

[0013] In another possible implementation form of the first aspect, the one or more current CSI values include multiple current CSI values, and the processing circuit is configured to quantize the multiple current CSI values using a vector quantization scheme to obtain the one or more current quantized CSI values.

[0014] According to a second aspect, a method for operating a user equipment (UE) to communicate with a base station is provided. The method comprises:

[0015] receiving one or more pilot signals from the base station;

[0016] estimating one or more current channel state information (CSI) values based on the one or more pilot signals from the base station;

[0017] quantizing the one or more current CSI values to obtain one or more current quantized CSI values;

[0018] The one or more current quantized CSI values are encoded based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values, wherein the cell-specific coding scheme defines a mapping from multiple possible quantized CSI values to multiple bit sequences with different numbers of bits, which can reduce the number of bits required to represent the CSI, thereby reducing communication overhead.

[0019] The method according to the second aspect of the present disclosure can be executed by the UE according to the first aspect of the present disclosure. Therefore, other features of the method according to the second aspect of the present disclosure are directly derived from the functions of the UE according to the first aspect of the present disclosure and the different implementation forms described in the context thereof.

[0020] According to a third aspect, a base station is provided for communicating with at least one user equipment (UE) within a coverage area (i.e., a cell of the base station). The base station includes a communication interface configured to send one or more pilot signals to the at least one UE and receive one or more current coded and quantized channel state information (CSI) values from the at least one UE based on the one or more pilot signals. The base station also includes processing circuitry configured to decode the one or more current coded and quantized CSI values based on a cell-specific decoding scheme. The cell-specific decoding scheme defines a mapping from multiple bit sequences having different numbers of bits to multiple possible quantized CSI values.

[0021] In another possible implementation form of the third aspect, the mapping defined by the cell-specific decoding scheme is configured to map the multiple bit sequences with different numbers of bits to multiple possible quantized CSI values based on the corresponding frequency of occurrence of each possible quantized CSI value in the multiple possible quantized CSI values.

[0022] In another possible implementation form of the third aspect, the mapping defined by the cell-specific decoding scheme is configured to map the bit sequence with the smallest number of bits among the multiple bit sequences to the possible quantized CSI value with the highest frequency of occurrence among the multiple possible quantized CSI values.

[0023] In another possible implementation form of the third aspect, the cell-specific decoding scheme is defined by one or more encoding codebooks.

[0024] In another possible implementation form of the third aspect, the communication interface is configured to send the one or more encoding codebooks to the at least one UE and / or enable the processing circuit of the at least one UE to generate or retrieve information of the one or more encoding codebooks.

[0025] In another possible implementation form of the third aspect, during the training phase, the communication interface of the base station is further configured to send one or more training pilot signals to the at least one UE, and receive one or more quantized training CSI values from the at least one UE, and the processing circuit of the base station is configured to determine the one or more encoding codebooks based on the one or more quantized training CSI values.

[0026] In another possible implementation form of the third aspect, the communication interface is further configured to send one or more quantization codebooks to the at least one UE and / or enable a processing circuit of the at least one UE to generate or retrieve information of the one or more quantization codebooks. The one or more quantization codebooks may enable the processing circuit of the at least one UE to generate one or more current coded quantized CSI values.

[0027] In another possible implementation manner of the third aspect, the one or more quantization codebooks define vector quantization.

[0028] According to a fourth aspect, a method of operating a base station to communicate with at least one user equipment (UE) is provided. The method comprises:

[0029] sending one or more pilot signals to the at least one UE;

[0030] receiving one or more current coded quantized channel state information (CSI) values from the at least one UE based on the one or more pilot signals;

[0031] The one or more currently encoded quantized CSI values are decoded based on a cell-specific decoding scheme, wherein the cell-specific decoding scheme defines a mapping from a plurality of bit sequences having different numbers of bits to a plurality of possible quantized CSI values.

[0032] The method according to the fourth aspect of the present disclosure can be performed by the base station according to the third aspect of the present disclosure. Therefore, other features of the method according to the fourth aspect of the present disclosure are directly derived from the functions of the base station according to the third aspect of the present disclosure and different implementation forms described in the context thereof.

[0033] According to a fifth aspect, a computer program product is provided, comprising a computer-readable storage medium for storing program code, and when the program code is executed by a computer or a processor, the program code causes the computer or the processor to perform the method according to the second aspect or the method according to the fourth aspect.

[0034] The following drawings and description set forth one or more embodiments in detail. Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following describes the embodiments of the present disclosure in more detail with reference to the accompanying drawings. In the accompanying drawings:

[0036] Figure 1 A base station according to an embodiment is shown in a communication cell for communicating with one or more user equipments (UEs) according to an embodiment;

[0037] Figure 2 shows different operation phases of a communication cell including a UE according to an embodiment and a base station according to an embodiment;

[0038] Figure 3 is a schematic signaling diagram illustrating an additional control signaling phase of cell-specific quantization and mapping between a UE according to an embodiment and a base station according to an embodiment;

[0039] Figure 4a and Figure 4b 1 is a schematic diagram showing a codebook for Huffman coding implemented by a UE according to an embodiment and a base station according to an embodiment;

[0040] Figure 4c 1 is a schematic diagram showing a codebook for joint Huffman coding implemented by a UE according to an embodiment and a base station according to an embodiment;

[0041] Figure 5a and Figure 5b 1 is a schematic diagram illustrating a codebook for cell-specific quantization and Huffman coding implemented by a UE according to an embodiment and a base station according to an embodiment;

[0042] Figure 5c 1 is a schematic diagram showing a codebook for joint quantization and Huffman coding implemented by a UE according to an embodiment and a base station according to an embodiment;

[0043] Figure 6 is a flowchart illustrating a method for operating a UE according to an embodiment to communicate with a base station according to an embodiment;

[0044] Figure 7 The present invention is a flow chart illustrating a method of operating a base station according to an embodiment to communicate with at least one UE according to an embodiment.

[0045] In the following, identical reference numerals refer to identical or at least functionally equivalent features. DETAILED DESCRIPTION

[0046] In the following description, reference is made to the accompanying drawings that form part of the present disclosure, which illustrate, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It should be understood that the embodiments of the present disclosure may be used in other aspects and include structural or logical changes not depicted in the accompanying drawings. Therefore, the following detailed description should not be taken as limiting, and the scope of the present disclosure is defined by the appended claims.

[0047] For example, it should be understood that the disclosure related to a described method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more units (e.g., functional units) to perform the described one or more method steps (e.g., one unit performs one or more steps, or each of multiple units performs one or more of the multiple steps), even if such one or more units are not explicitly described or shown in the accompanying drawings. On the other hand, for example, if a specific device is described based on one or more units (e.g., functional units), the corresponding method may include a step to perform the function of one or more units (e.g., one step performs the function of one or more units, or each of multiple steps performs the function of one or more of the multiple units), even if such one or more steps are not explicitly described or shown in the accompanying drawings. Furthermore, it should be understood that, unless otherwise explicitly stated, the features of the various exemplary embodiments and / or aspects described herein may be combined with each other.

[0048] Figure 1 1 shows a base station 130 according to an embodiment in a communication cell 100 of a cellular communication network (e.g., a 5G cellular communication network) for communicating with one or more user equipments (UEs) 110 according to an embodiment. The communication cell 100 may be one of a plurality of communication cells of the cellular communication network. Figure 1 As shown, UE 110 may be within a coverage area 150, i.e., within a cell of a base station 130, which may be implemented as a gNB 130. UE 110 may be any device capable of communicating with base station 130, such as a smartphone. Figure 1 As shown, UE 110 includes processing circuitry 111 and a communication interface 113. Processing circuitry 111 can be implemented in hardware and / or software and can include digital circuitry, or both analog and digital circuitry. The digital circuitry can include components such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or a general-purpose processor. The memory 115 of UE 110 can be configured to store executable program code that, when executed by processing circuitry 111, causes UE 110 to perform the functions and methods described herein.

[0049] Similarly, base station 130 includes processing circuitry 131 and a communication interface 133. Processing circuitry 131 can be implemented in hardware and / or software and can include digital circuitry, or both analog and digital circuitry. The digital circuitry can include components such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or a general-purpose processor. The memory 135 of base station 130 can be configured to store executable program code that, when executed by processing circuitry 131, causes base station 130 to perform the functions and methods described herein.

[0050] The communication interface 133 of the base station 130 is configured to send one or more pilot signals to at least one UE 110. Complementarily, the communication interface 113 of the UE 110 is configured to receive one or more pilot signals from the base station 130.

[0051] As will be described in greater detail below, processing circuitry 111 of UE 110 is configured to estimate one or more current channel state information (CSI) values based on one or more pilot signals from base station 130. Processing circuitry 111 of UE 110 is further configured to quantize the one or more current CSI values to obtain one or more current quantized CSI values, and encode the one or more current quantized CSI values based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values. The cell-specific coding scheme defines a mapping from multiple possible quantized CSI values to multiple bit sequences having different numbers of bits.

[0052] Communication interface 113 of UE 110 may also be configured to send one or more current coded quantized CSI values to base station 130. Communication interface 133 of base station 130 is configured to receive one or more current coded quantized CSI values from at least one UE 110 based on one or more pilot signals.

[0053] The processing circuit 131 of the base station 130 is configured to decode one or more currently encoded quantized CSI values based on a cell-specific decoding scheme. Complementary to the cell-specific encoding scheme, the cell-specific decoding scheme defines a mapping from multiple bit sequences with different numbers of bits to multiple possible quantized CSI values.

[0054] The mapping defined by the cell-specific coding scheme may be configured to map the multiple possible quantized CSI values to multiple bit sequences with different numbers of bits based on the corresponding frequency of occurrence of each possible quantized CSI value in the multiple possible quantized CSI values. Complementarily, the mapping defined by the cell-specific decoding scheme may be configured to map the multiple bit sequences with different numbers of bits to the multiple possible quantized CSI values based on the corresponding frequency of occurrence of each possible quantized CSI value in the multiple possible quantized CSI values.

[0055] The mapping defined by the cell-specific coding scheme can be configured to map the possible quantized CSI value with the highest frequency among multiple possible quantized CSI values to the bit sequence with the smallest number of bits among multiple bit sequences. Complementarily, the mapping defined by the cell-specific decoding scheme can be configured to map the bit sequence with the smallest number of bits among multiple bit sequences to the possible quantized CSI value with the highest frequency among multiple possible quantized CSI values.

[0056] As will be described in more detail below, a cell-specific encoding scheme may be defined by one or more encoding codebooks. Complementarily, a cell-specific decoding scheme may be defined by one or more encoding codebooks.

[0057] The communication interface 133 of the base station 130 may be configured to send one or more encoding codebooks to the at least one UE 110 and / or enable the processing circuit 111 of the at least one UE 110 to generate or retrieve information of the one or more encoding codebooks. Complementarily, the communication interface 113 of the UE 110 may be configured to receive one or more encoding codebooks from the base station 130 and / or enable the processing circuit 111 of the UE 110 to generate or retrieve information of the one or more encoding codebooks.

[0058] As will be described in more detail below, the communication interface 133 of the base station 130 may also be configured to send one or more quantization codebooks to the at least one UE 110 and / or enable the processing circuit 111 of the at least one UE 110 to generate or retrieve information of the one or more quantization codebooks. The one or more quantization codebooks may enable the processing circuit 111 of the at least one UE 110 to generate one or more current coded quantized CSI values. The one or more quantization codebooks may define vector quantization.

[0059] Complementarily, the communication interface 113 of the UE 110 may be configured to receive one or more quantization codebooks from the base station 130 and / or enable the processing circuit 111 of the UE 110 to generate or retrieve information of the one or more quantization codebooks. The processing circuit 111 of the UE 110 may be configured to quantize one or more current CSI values based on the one or more quantization codebooks to obtain one or more current quantized CSI values.

[0060] The one or more current CSI values may include multiple current signal-to-interference-plus-noise ratio (SINR) values, and the one or more quantization codebooks may include a first quantization codebook for quantizing a peak value of the multiple current SINR values and a second quantization codebook for quantizing one or more difference values relative to the peak value in the multiple current SINR values. Additionally or alternatively, the one or more current CSI values may include multiple current CSI values, and the processing circuit 111 of the UE 110 may be configured to quantize the multiple current CSI values using a vector quantization scheme to obtain one or more current quantized CSI values.

[0061] According to one embodiment, UE 110 and base station 130 may be configured for adaptive mapping and joint quantization to achieve CSI information refinement. This may include one or more of the following steps, which are further detailed below. For clarity, this will be referred to as an SINR-based approach. However, it will be understood that UE 110 and base station 130 may also be configured for a precoder-based approach or an approach based on any other quantity related to determining or characterizing channel state information, wherein each SINR value is replaced by a precoder or any other quantity.

[0062] The first step may include sending one or more quantization codebooks for joint quantization of multiple SINRs from the base station 130. The quantization codebook (ie, dictionary) may be sent to any UE 110 entering the communication cell 100 for the first time.

[0063] The second step may include sending, from the base station 130, mapping functions to be used by at least one UE 110 for quantization values. These mapping functions may be represented by, for example, a coding codebook, which may be a dictionary of quantization indices and bit sequences to be transmitted and may be sent to any UE 110 entering the communication cell 100 for the first time. The bit sequences of the mapping functions (particularly the coding codebook) may have variable lengths based on the propagation conditions of the communication cell 100. Because different channels may occur with varying probabilities in each communication cell 100, e.g., depending on the location of scatterers in the communication cell 100, shorter bit sequences may be used for more common quantization codewords, while longer bit sequences may be used for less frequently occurring quantization codewords. Thus, a cell-specific mapping may be achieved. The second step may also be implemented using a conventional quantizer, as described further below.

[0064] The third step may include: UE 110 jointly quantizing multiple SINR values related to the CSI-RS according to the quantization codebook obtained in the first step. Here, the quantization codebook in the first step may be used to quantize the SINR vector. The quantization may be performed on the entire SINR set, that is, the quantization may be a joint quantization.

[0065] The fourth step may include: UE 110 mapping the quantized value into a bit sequence according to the mapping function (especially the encoding codebook) of the second step. This mapping may also be performed when quantization is performed according to a traditional method (ie, without using the joint quantization of the third step).

[0066] Figure 2 1 shows different operation phases of a communication cell 100 including a UE 110 according to an embodiment and a base station 130 according to an embodiment. Corresponding to two temporally different phases, the operation phase of the communication cell 100 may include a training phase 210 (during Figure 2 ) and the utilization phase 220 (also referred to as the training phase in Figure 2 Also referred to as the utilization state in [Context missing].

[0067] Typically, during the training phase 210 , the communication cell 100 may be configured to design quantization and mapping parameters, such as codebooks and dictionaries, in particular one or more quantization codebooks and one or more encoding codebooks.

[0068] Typically, in the utilization phase 220, the communication cell 100 may be configured to use the acquired quantization and mapping parameters, such as codebooks and dictionaries, in particular one or more quantization codebooks and one or more encoding codebooks.

[0069] More specifically, during the training phase 210 , the base station 130 may transmit a CSI-RS signal to the UE 110 .

[0070] Based on this, Figure 2 As shown in step 211 , UE 110 may perform CSI estimation based on (but not limited to) SINR measurement, for example, according to an option of the 3GPP standard.

[0071] Then, in Figure 2 In steps 212 and 213, UE 110 may quantize and map the SINR measurement value according to the 3GPP standard, and may feed back the obtained bits to base station 130. More specifically, Figure 2 Steps 210 to 213 may include: the base station 130 uses a specific beamformer to transmit in different transmission directions (eg, equally spaced within a sector identified by the initial access process in the communication cell 100) CSI-RS. UE 110 can measure the SINR of each received CSI-RS to obtain real-valued measurement vector UE 110 may select A subset of the CSI-RS, and reporting these to the base station 130 The indices of the CSI-RSs and the quantized and mapped versions of their SINR values.

[0072] exist Figure 2 In step 214, the base station 130 may demap the received bits to reconstruct the SINR value.

[0073] When UE 110 moves in communication cell 100 for a considerable period of time, for example, base station 130 sends a CSI-RS signal to UE 110 and subsequent steps 211 to 214 may be repeated multiple times by UE 110 and may be repeated multiple times by base station 130 accordingly.

[0074] exist Figure 2 In steps 215 and 216, the base station 130 may calculate statistics of the collected SINR values and may perform quantization and mapping parameter design. Once a long data set of quantized CSI values has been collected, steps 215 and 216 may be performed, and the training phase 210 may end. Steps 215 and 216 may cause the base station 130 to generate one or more quantization codebooks for quantization and one or more encoding codebooks for mapping, which are cell-specific. In addition, the quantizer implemented by the processing circuit 131 of the base station 130 (i.e., the quantizer for generating the one or more quantization codebooks) may perform a joint operation on the L selected SINR values, and the dictionary (i.e., the one or more encoding codebooks) may provide an appropriate mapping for the joint quantized value and a variable-length bit sequence for each quantized value.

[0075] It will be appreciated that the training phase 210 may be repeated periodically and / or when needed as cell propagation conditions of the communication cell 100 change.

[0076] In the utilization phase 220, for each new UE 110 entering the communication cell 100, the base station 130 may transmit a dictionary for mapping, such as one or more encoding codebooks, to the UE 110. Similarly, the base station 130 may provide one or more quantization codebooks to the corresponding UE 110. The base station 130 may then send a CSI-RS signal to the UE 110.

[0077] exist Figure 2 In step 221, UE 110 may perform CSI estimation based on SINR measurement values or channel vectors.

[0078] exist Figure 2In step 223 , UE 110 may perform cell-specific quantization using a quantizer (ie, based on one or more quantization codebooks), wherein the L SINR values may be jointly and / or individually calculated, as defined in step 215 of training phase 210 .

[0079] exist Figure 2 In step 225 of , UE 110 may perform cell-specific mapping of quantization values to bit sequences using a dictionary (e.g., one or more encoding codebooks) generated by base station 130 at the end of the training phase (i.e., at step 216 of training phase 210). UE 110 may then send the bit sequence to base station 130.

[0080] exist Figure 2 In step 227 of the training phase 210, the base station 130 may perform cell-specific demapping to obtain quantized values from the bit sequence using the parameters (i.e., one or more encoding codebooks) established at the end of the training phase 210 (i.e., at step 216 of the training phase 210).

[0081] In other words, during the training phase 210, the communication interface 133 of the base station 130 may be further configured to send one or more training pilot signals to the at least one UE 110, and receive one or more quantized training CSI values from the at least one UE 110. The processing circuit 131 may be further configured to determine one or more encoding codebooks based on the one or more quantized training CSI values.

[0082] Figure 3 is a schematic signaling diagram illustrating an additional control signaling phase of cell-specific quantization and mapping between a UE 110 according to an embodiment and a base station 130 according to an embodiment.

[0083] exist Figure 3 In step 301, the cell-specific quantization signaling may include the following: Figures 4a to 4c and Figures 5a to 5c The embodiments further describe a dictionary of vectors used by UE 110 to quantize SINR.

[0084] exist Figure 3 In step 303, the cell-specific mapping signaling may include the following: Figures 4a to 4c and Figures 5a to 5c As further described in the embodiments of the present invention, each index of the quantized value is mapped to a dictionary in a variable length bit sequence.

[0085] exist Figure 3 In step 305, the base station 130 may perform CSI-RS broadcasting.

[0086] exist Figure 3In step 307, the CSI feedback from UE 110 may be based on a variable number of feedback bits, eg, a variable number of feedback bits different from the 3GPP standard.

[0087] It will be appreciated that implementing cell-specific quantization and / or mapping may require base station 130 to transmit a mapping dictionary to UE 110, i.e., the bit sequence corresponding to each quantization value to be fed back. The set of selected bit sequences may be transmitted by explicitly providing the set or by providing parameters to be used in a predefined model (e.g., a binary function that gives the set as output). Alternatively, the set of selected bit sequences may be transmitted by providing an index of the set in a group of predefined bit sequence sets.

[0088] Figure 4a and Figure 4b FIG. 1 is a schematic diagram showing a codebook for Huffman coding implemented by a UE 110 and a base station 130 according to an embodiment.

[0089] During the training phase 210, the UE 110 may report the individually quantized SINR measurements. The base station 130 may construct two Huffman dictionaries 410a and 410b, one for quantized peak values, i.e., peak dictionary 410a, and one for collected differential measurements, i.e., differential dictionary 410b. The two Huffman dictionaries 410a and 410b include a specific mapping for each codeword based on the SINR measurements reported by all UEs 110 participating in the training phase 210. Depending on the Huffman coding scheme, this may include using shorter bit sequences for more frequently occurring codewords and longer bit sequences for less frequently occurring codewords.

[0090] In the utilization phase 220, the base station 130 may send CSI-RS signal. UE 110 can CSI-RS signals are measured for SINR and vector UE 110 can quantize the SINR measurement value according to the 3GPP standard method and obtain the vector UE 110 may transmit back to base station 130: (i) the binary codeword 401a mapped to the peak dictionary entry 403 corresponding to the quantized SINR peak and (ii) the binary codeword 401b mapped to the peak dictionary entry 403 corresponding to the quantized SINR peak. The differential dictionary entries 405 corresponding to the differential SINRs The base station 130 can then use the same Huffman dictionary 410a and 410b to retrieve the binary codeword 401b. .

[0091] Here, in Figure 3 The parameters to be sent from the base station 130 to the UE 110 in the additional control signaling phase shown are two constructed Huffman dictionaries 410a and 410b. It can be understood that although the quantization adopted is implemented according to the 3GPP standard, that is, the quantization is not performed jointly between the SINR, Figure 4a and Figure 4b The mapping scheme is cell-specific and has a variable length bit sequence.

[0092] Figure 4c FIG. 1 is a schematic diagram showing a codebook for joint Huffman coding implemented by a UE 110 according to an embodiment and a base station 130 according to an embodiment.

[0093] During the training phase 210, the UE 110 may report the individually quantized SINR measurements. The base station 130 may construct a single Huffman dictionary 410c and a specific mapping for each codeword without distinguishing between peak SINR and differential SINR values, where each codeword represents Quantized vectors in a dimensional vector space.

[0094] In the utilization phase 220, the base station 130 may send CSI-RS signal. UE 110 can CSI-RS signals are measured for SINR and vector UE 110 can quantize the SINR measurement value according to the 3GPP standard method and obtain the vector UE 110 may transmit back to base station 130 the data mapped to the quantized SINR vector The base station 130 can use the same codebook 410c to retrieve the binary codeword 401c of the corresponding Huffman dictionary entry 407. .

[0095] Here, in Figure 3 The parameter sent from base station 130 to UE 110 during the additional control signaling phase is a constructed joint Huffman dictionary 410c, which includes a relevant mapping bit sequence. Although each SINR is still quantized individually, the entire set of quantized SINR values is jointly mapped, thereby partially realizing the advantages of joint quantization. In addition, the mapping is cell-specific.

[0096] Figure 5a and Figure 5b FIG. 1 is a schematic diagram illustrating a codebook for cell-specific quantization and Huffman coding implemented by a UE 110 according to an embodiment and a base station 130 according to an embodiment.

[0097] During the training phase 210, the UE 110 may report to the base station 130 SINR measurements (non-quantized). The base station 130 may construct two cell-specific quantizers, each operating on a scalar, one for the collected peak SINR measurements and one for the collected differential SINR measurements, i.e., as described above. Figure 2 As described in steps 211 to 214 of FIG5 , both have the same number of bits as in the 3GPP standard, namely 7 and 4, respectively. The quantizer parameters can be optimized based on the cell-specific SINR measurements. Two compressed Huffman dictionaries 510a and 510b, one for peak SINR values and one for differential SINR values, including relative mapping bit sequences, can be constructed by base station 130 starting from the cell-specific quantizer.

[0098] In the utilization phase 220, the base station 130 may send CSI-RS signal. UE 110 can CSI-RS signals are used to measure SINR, and a vector of SINR values can be obtained UE 110 may use the obtained cell-specific quantization codebook to quantize the SINR measurement value and obtain the vector These codebooks can be designed based on the probability of observing a specific peak / differential SINR value in the communication cell 100. For example, a clustering algorithm can provide a codebook of centroids to which the measured SINR values can be mapped with the minimum Euclidean distance. The UE 110 can transmit back to the base station 130 the following items: (i) a binary codeword 501a mapped to a peak dictionary entry 503 corresponding to the quantized SINR peak and (ii) a binary codeword 501b mapped to a peak dictionary entry 503 corresponding to the quantized SINR peak. The differential dictionary entries 505 corresponding to the differential SINRs The base station 130 can use the same mapping codebook to retrieve the binary codeword 501b. .

[0099] Here, in Figure 3 The parameters to be sent to UE 110 during the additional control signaling phase are two constructed Huffman dictionaries 510a and 510b. In this case, although joint quantization is not performed, both the quantization and mapping are cell-specific. It will be appreciated that UE 110 (and other UEs in the communication cell) may also receive corresponding quantization dictionaries.

[0100] Figure 5c FIG. 1 is a schematic diagram showing a codebook for joint quantization and Huffman coding implemented by a UE 110 according to an embodiment and a base station 130 according to an embodiment.

[0101] During the training phase 210, ,in, is the number of quantization bits, UE 110 can use the vector Report to base station 130 SINR measurement values (non-quantized). The base station 130 can construct vectors The quantization codebook consists of , where the length of each vector is For example, vector quantization can be performed using the Linde-Buzo-Gray algorithm. In this case, the codebook vector This can be done by training a vector of size M Obtained by clustering The base station 130 can construct a single Huffman dictionary 510c and a specific mapping for each codebook vector without distinguishing between peak SINR and differential SINR values, where each codebook vector represents Quantized vectors in a dimensional vector space.

[0102] In the utilization phase 220, the base station 130 may send CSI-RS signal. UE 110 can The SINR of each CSI-RS signal is measured and the vector is obtained. UE 110 can use the vector Mapping to quantized vector (Right now , }), the quantized vector relative to The Euclidean distance of is minimized. UE 110 may transmit back to base station 130 the binary codeword 501c mapped to the Huffman dictionary entry 507 corresponding to the quantized vector The base station 130 can use the same Huffman dictionary 510c to search .

[0103] Here, in Figure 3 The parameter to be sent to UE 110 during the additional control signaling phase is the constructed Huffman dictionary 510c. This embodiment corresponds to full joint quantization and mapping using a cell-specific codebook and mapping dictionary. It will be appreciated that UE 110 (and other UEs in the communication cell) may also receive a corresponding quantization dictionary.

[0104] As mentioned above, although the above embodiment describes the quantization and mapping of the feedback SINR value, a similar method can be used for other CSI data.

[0105] Figure 6 FIG. 6 is a flow chart illustrating a method 600 for operating a user equipment (UE) 110 according to an embodiment to communicate with a base station 130 according to an embodiment.

[0106] The method 600 includes step 601 of receiving one or more pilot signals from a base station 130 .

[0107] The method 600 further includes step 603 of estimating one or more current channel state information (CSI) values based on one or more pilot signals from the base station 130 .

[0108] The method 600 further includes step 605: quantizing the one or more current CSI values to obtain one or more current quantized CSI values.

[0109] Method 600 also includes step 607: encoding one or more current quantized CSI values based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values, wherein the cell-specific coding scheme defines a mapping from multiple possible quantized CSI values to multiple bit sequences with different numbers of bits.

[0110] Since the method 600 may be implemented by the UE 110 , other features of the method 600 are directly derived from the functionality of the UE 110 and the different embodiments described in its context.

[0111] Figure 7 FIG. 7 is a flow chart illustrating a method 700 of operating a base station 130 according to an embodiment to communicate with at least one user equipment (UE) 110 according to an embodiment.

[0112] The method 700 includes step 701 of sending one or more pilot signals to at least one UE 110 .

[0113] The method 700 includes step 703 of receiving one or more current coded quantized channel state information (CSI) values from at least one UE 110 based on one or more pilot signals.

[0114] The method 700 includes step 705 of decoding one or more currently encoded quantized CSI values based on a cell-specific decoding scheme, wherein the cell-specific decoding scheme defines a mapping from a plurality of bit sequences with different numbers of bits to a plurality of possible quantized CSI values.

[0115] Since the method 700 can be implemented by the base station 130 , other features of the method 700 are directly derived from the functionality of the base station 130 and different embodiments described in the context thereof.

[0116] The embodiments disclosed herein solve the technical problem by introducing a cell-specific solution and more efficient mapping and joint quantization to reduce the average amount of bits required for UE 110 to provide feedback without affecting the feedback quality.

[0117] In particular, by joint quantization of the L selected SINRs, possible correlations between observations that recur in the considered communication cell 100 can be exploited. This reduces the amount of feedback required without sacrificing accuracy.

[0118] Furthermore, the use of a cell-specific quantization codebook exploits the unique propagation conditions of each cell, using more quantization values corresponding to the most frequently occurring SINR values. This provides more accurate CSI feedback without increasing overhead.

[0119] Furthermore, using a cell-specific mapping with variable-length bit sequences to represent (and feed back) the quantized values exploits different statistics of the quantized values (still dependent on the cell propagation conditions) and reduces the amount of feedback without sacrificing accuracy.

[0120] Those skilled in the art should understand that the “blocks” (“units”) in the various figures (methods and devices) represent or describe the functions of the embodiments of the present disclosure (and are not necessarily independent “units” in hardware or software), thereby equally describing the functions or features of the device embodiments and the method embodiments (units are equivalent to steps).

[0121] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the described embodiments of the device are merely exemplary. For example, the unit division is merely a logical functional division, and other divisions may be used in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not performed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be achieved by using some interfaces. The indirect coupling or communication connection between devices or units can be achieved in electronic form, mechanical form, or other forms.

[0122] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, may be located in one location, or may be distributed across multiple network units. Some or all of the units may be selected as needed to achieve the purpose of the embodiment.

[0123] Furthermore, the functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

Claims

1. A user equipment UE (110) for communicating with a base station (130), wherein: The UE (110) includes: a communication interface (113) configured to receive one or more pilot signals from the base station (130); The processing circuit (111) is configured to: estimating one or more current channel state information (CSI) values based on the one or more pilot signals from the base station (130); quantizing the one or more current CSI values to obtain one or more current quantized CSI values; The one or more current quantized CSI values are encoded based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values, wherein the cell-specific coding scheme defines a mapping from multiple possible quantized CSI values to multiple bit sequences with different numbers of bits.

2. The UE (110) according to claim 1, wherein: The communication interface (113) is further configured to send the one or more current coded quantized CSI values to the base station (130).

3. The UE (110) according to claim 1 or 2, wherein: The mapping defined by the cell-specific coding scheme is configured to map the multiple possible quantized CSI values to the multiple bit sequences with different numbers of bits according to the corresponding occurrence frequency of each possible quantized CSI value in the multiple possible quantized CSI values.

4. The UE (110) according to claim 3, wherein: The mapping defined by the cell-specific coding scheme is configured to map a possible quantized CSI value that occurs most frequently among the multiple possible quantized CSI values to a bit sequence with a minimum number of bits among the multiple bit sequences.

5. The UE (110) according to any of the preceding claims, wherein The cell-specific coding scheme is defined by one or more coding codebooks.

6. The UE (110) according to claim 5, wherein: The communication interface (113) is configured to receive the one or more encoding codebooks from the base station (130) and / or enable the processing circuit (111) to generate or retrieve information of the one or more encoding codebooks.

7. The UE (110) according to any of the preceding claims, wherein The communication interface (113) is further configured to receive one or more quantization codebooks from the base station (130) and / or enable the processing circuit (111) to generate or retrieve information of the one or more quantization codebooks, wherein the processing circuit 111 is configured to quantize the one or more current CSI values based on the one or more quantization codebooks to obtain the one or more current quantized CSI values.

8. The UE (110) according to claim 7, wherein: The one or more current CSI values include a plurality of current signal-to-interference and noise ratio (SINR) values, wherein the one or more quantization codebooks include a first quantization codebook for quantizing a peak value of the plurality of current SINR values and a second quantization codebook for quantizing one or more difference values of the plurality of current SINR values relative to the peak value.

9. The UE (110) according to any of the preceding claims, wherein The one or more current CSI values include a plurality of current CSI values, wherein the processing circuit (111) is configured to quantize the plurality of current CSI values using a vector quantization scheme.

10. A method (600) for operating a user equipment (UE) (110) to communicate with a base station (130), wherein: The method (600) comprises: receiving (601) one or more pilot signals from the base station (130); estimating (603) one or more current channel state information (CSI) values based on the one or more pilot signals from the base station (130); quantizing the one or more current CSI values (605) to obtain one or more current quantized CSI values; The one or more current quantized CSI values are encoded (607) based on a cell-specific coding scheme to obtain one or more current coded quantized CSI values, wherein the cell-specific coding scheme defines a mapping from a plurality of possible quantized CSI values to a plurality of bit sequences having different numbers of bits.

11. A base station (130) for communicating with at least one user equipment UE (110), wherein: The base station (130) comprises: a communication interface (133) configured to send one or more pilot signals to the at least one UE (110), and to receive one or more current coded quantized channel state information (CSI) values from the at least one UE (110) based on the one or more pilot signals; The processing circuit (131) is configured to decode the one or more currently encoded quantized CSI values based on a cell-specific decoding scheme, wherein the cell-specific decoding scheme defines a mapping from a plurality of bit sequences having different numbers of bits to a plurality of possible quantized CSI values.

12. The base station (130) according to claim 11, wherein The mapping defined by the cell-specific decoding scheme is configured to map the plurality of bit sequences having different numbers of bits to a plurality of possible quantized CSI values according to a corresponding frequency of occurrence of each of the plurality of possible quantized CSI values.

13. The base station (130) according to claim 12, wherein The mapping defined by the cell-specific decoding scheme is configured to map a bit sequence having a minimum number of bits among the multiple bit sequences to a possible quantized CSI value having the highest occurrence frequency among the multiple possible quantized CSI values.

14. The base station (130) according to any one of claims 11 to 13, wherein The cell-specific decoding scheme is defined by one or more encoding codebooks.

15. The base station (130) according to claim 14, wherein The communication interface (133) is configured to send the one or more encoding codebooks to the at least one UE (110) and / or enable a processing circuit (111) of the at least one UE (110) to generate or retrieve information of the one or more encoding codebooks.

16. The base station (130) according to claim 14 or 15, wherein During a training phase, the communication interface (133) is further configured to send one or more training pilot signals to the at least one UE (110), and to receive one or more quantized training CSI values from the at least one UE (110), wherein the processing circuit (131) is configured to determine the one or more encoding codebooks based on the one or more quantized training CSI values.

17. The base station (130) according to any one of claims 11 to 16, wherein The communication interface (133) is further configured to send one or more quantization codebooks to the at least one UE (110) and / or enable a processing circuit (111) of the at least one UE (110) to generate or retrieve information of the one or more quantization codebooks, wherein the one or more quantization codebooks enable the processing circuit (111) of the at least one UE (110) to generate the one or more current coded quantized CSI values.

18. The base station (130) according to claim 17, wherein The one or more quantization codebooks define vector quantization.

19. A method (700) of operating a base station (130) to communicate with at least one user equipment (UE) (110), wherein: The method (700) comprises: sending (701) one or more pilot signals to the at least one UE (110); receiving (703) one or more current coded quantized channel state information (CSI) values from the at least one UE (110) based on the one or more pilot signals; The one or more currently encoded quantized CSI values are decoded (705) based on a cell-specific decoding scheme, wherein the cell-specific decoding scheme defines a mapping from a plurality of bit sequences having different numbers of bits to a plurality of possible quantized CSI values.

20. A computer program product, wherein A computer-readable storage medium is provided for storing program code, which, when executed by a computer or a processor, causes the computer or the processor to perform the method (600) according to claim 10 or the method (700) according to claim 19.

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