Communication apparatuses and methods for wireless communication

Abstract

A first communication apparatus configured to transmit CSI report configuration message to a second communication apparatus comprising a User Equipment (UE), the CSI report configuration message includes an indicator for a performance codebook for the UE and an indicator for an interference codebook for the UE. The performance codebook is for preferred precoder reporting and the interference codebook is for interference direction reporting. The first communication apparatus is configured to transmit a reference signal to the second communication apparatus comprising the UE and receive a CSI report from the second communication apparatus comprising the UE. The CSI report comprises a precoding matrix indicator, indicating a performance codeword selected from the performance codebook as the UE's preferred precoder, and an interference matrix indicator, indicating an interference codeword selected from the interference codebook. The interference codeword indicating an interference direction, that meets either an interference condition or a non-interference condition thereby reporting either a strong interference or a weak interference, respectively.

Description

[0001] COMMUNICATION APPARATUSES AND METHODS FOR WIRELESS COMMUNICATION

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to the field of wireless communication systems; and more specifically, to a communication apparatus and methods for wireless communication.

[0004] BACKGROUND

[0005] In modern wireless communication systems, particularly in 5G and beyond, downlink Multi-User Multiple-Input Multiple-Output (MU-MIMO) technology has become a cornerstone for improving spectral efficiency and supporting higher data rates. In such systems, a Base Station (BS) equipped with multiple antennas communicates simultaneously with multiple User Equipments (UEs), requiring efficient scheduling and precoding strategies for effective communication. To optimize scheduling and precoding processes, the BS relies on Channel State Information (CSI) feedback received from the UEs. The conventional CSI feedback mechanisms often based on predefined codebooks report preferred precoding directions, enabling the BS to determine transmission strategies. However, the conventional approaches exhibit several limitations. For instance, the conventional approaches primarily focus on preferred precoding directions feedback from the UEs without a systematic codebook-based reporting of strong interfering directions that degrade communication quality or weak interfering directions that could be utilized for co-scheduling. Additionally, conventional solutions that incorporate interference reporting typically rely on no-codebook or single-codebook designs, which constrain flexibility when pairing multiple UEs with differing rate requirements. These limitations result in suboptimal resource allocation, increased interference, and reduced network efficiency.

[0006] Consequently, there exists a technical problem of inadequate feedback of interference-related directions in existing CSI feedback wireless communication systems.

[0007] Therefore, in light of the foregoing discussion, there exists a need for an improved CSI feedback mechanism that can efficiently inform the BS of both preferred precoding directions and interference-related directions for enhancing scheduling and precoding effectiveness.

[0008] SUMMARY

[0009] An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art and provides an improved CSI feedback mechanism that can efficiently inform the BS of both preferred precoding directions and interference-related directions for enhancing scheduling and precoding effectiveness. The improved CSI feedback is achieved through the use of mixed codebooks that allocate more feedback bits to preferred precoding directions and fewer bits to interference-related directions. The balanced feedback allocation provides the base station with more accurate and comprehensive information for scheduling and precoding processes.

[0010] The object of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

[0011] In one aspect, the present disclosure provides a first communication apparatus configured to transmit a CSI report configuration message to a second communication apparatus comprising a User Equipment, UE (UEk). The CSI report configuration message comprising an indicator for a performance codebook (CPik) for the UE (UEk) and an indicator for an interference codebook (C;for the UE (UEk). The performance codebook (CP k) is for preferred precoder reporting and the interference codebook (C;is for interference direction reporting. The first communication apparatus is further configured to transmit a reference signal to the second communication apparatus comprising the UE (UEk) and receive a Channel State Information, CSI, reportfrom the second communication apparatus comprising the UE (UEk). The CSI report comprises a Precoding Matrix Indicator, PMI, (JPindicating a performance codeword selected from the performance codebook (CPik) by the UE (UEk) as the UE’s (UEk) preferred precoder from the performance codebook (CP k). The CSI report further comprises an Interference Matrix Indicator, IMI, (J / k). indicating an interference codeword selected from the interference codebook (C / k) by the UE (UEk). The interference codeword indicates an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction.

[0012] The disclosed first communication apparatus utilizes a unified approach that supports simultaneous reporting of both preferred precoding and interference directions. Specifically, the first communication apparatus is configured to transmit the CSI report configuration message to the second communication apparatus comprising the UE, (UEk), which includes indicators for the performance codebook (CP k) and the interference codebook (C / k). The performance codebook and the interference codebooks enable the first communication apparatus to provide more granular control, with the performance codebook guiding preferred precoder selection and the interference codebook for identifying interference directions. The PMI identifies the UE's preferred precoder, while the IMI reports interference directions, distinguishing between strong interference directions and those with minimal interference. This comprehensive approach allows the first communication apparatus to adapt dynamically to varying channel conditions, thereby improving the accuracy and reliability of communication in diverse scenarios.

[0013] In an implementation form, the first communication apparatus is further configured to perform scheduling and / or computing a precoder based on the IMI (J / k)~ and the PMI (JP kJ-

[0014] By utilizing the PMI (3P k), the first communication apparatus identifies the UE’s preferred precoder directions, which ensures an efficient and reliable data transmission. Concurrently, the IMI (3I k) provides feedback on interference-related directions, identifying either strong interfering directions to avoid or weak interfering directions that can be reused by other UEs resulting in data communication with enhanced efficacy.

[0015] In a further implementation form, the first communication apparatus is further configured to receive the Interference Matrix Indicator, IMIk), by receiving a first Interference Matrix Indicator, IMI (J / I ik). indicating a first interference direction being a direction that meets the interference condition, the first IMI thereby reporting a strong interference direction, and receiving a second Interference Matrix Indicator, IMI (J / 2ik). indicating a second interference direction being a direction that meets the non-interference condition, the second IMI thereby reporting a weak interference direction.

[0016] By distinguishing between strong and weak interference directions, the first communication apparatus gains granular insight into the channel conditions as experienced by the UE. By incorporating both the first IMI

[0017]

[0018] and the second IMI (J;2 k) into scheduling and precoding decisions, the first communication apparatus enhances spectral efficiency, improves signal quality for all UEs, and reduces the likelihood of interference.

[0019] In a further implementation form, the CSI report configuration message includes an indicator for a strong interference codebook andanindicator for a weak interference codebook (C / 2 k).

[0020] The strong interference codebook (C[l k) is used to represent directions with significant interference, allowing the second communication apparatus comprising the UE to provide high-accuracy feedback for these critical directions. Conversely, the weak interference codebook (C;2 k) is used for directions with minimal interference, which typically require less precision. Byexplicitly defining separate codebooks for strong and weak interference, the first communication apparatus ensures that the UE can tailor its feedback to the specific interference conditions observed in the channel.

[0021] In a further implementation form, the strong interference codebook (Cji, / <) is a Type II codebook and the weak interference codebook (CI2 k) is a Type I codebook.

[0022] By allocating more feedback resources to strong interference directions and fewer to weak ones, the first communication apparatus judiciously allocates overall feedback overhead and supports dynamic adaptation to varying interference scenarios, enabling better throughput and system reliability in multi-user environments.

[0023] In a further implementation form, the CSI report configuration message includes an interference condition and / or a noninterference condition.

[0024] By incorporating the interference condition and / or the non-interference condition into the CSI report configuration message, the first communication apparatus can control the conditions that the UE uses to differentiate between strong interference directions and weak interference directions.

[0025] In a further implementation form, the CSI Report includes one PMI, (JP k), and one IMI, (J; k), per (subjband utilized.

[0026] Reporting one PMI (P k) and one IMI (I k) for each utilized (subjband ensures that the first communication apparatus receives detailed band- specific or subband-specific information about the UE's channel state. This granular feedback enables the first communication apparatus to make precise scheduling and precoding decisions tailored to the specific channel conditions of each (subjband. This implementation enables efficient use of available channel resources, reduces inter-user interference, and enables higher throughput in the communication network.

[0027] In a further implementation form, the performance codebook (CP k) has an accuracy that is higher than the accuracy of the interference codebook (C; k).

[0028] By allocating fewer feedback bits to the interference codebook (Cl k) and more to the performance codebook CP k), the first communication apparatus prioritizes the accurate representation of preferred precoding directions while maintaining sufficient information about interference conditions to enable effective interference management.

[0029] In a further implementation form, the performance codebook (CP k) is a Type II codebook.

[0030] By adopting the Type II codebook for the performance codebook (CP k) the first communication apparatus prioritizes accurate representation of the strongest directions, which carry the data.

[0031] In a further implementation form, the interference codebook (C; k) is a Type I codebook.

[0032] By using the Type I codebook for the interference codebook (C’ / , / <), the first communication apparatus gains information to mitigate interference and optimize resource allocation, resulting in improved spectral efficiency, reduced latency, and enhanced overall network performance.In a further implementation form, the interference codebook ( / is a Type II codebook when reporting strong interference, and a Type I codebook when reporting weak interference. By dynamically selecting the appropriate codebook type based on the interference to report, the first communication apparatus optimizes the use of feedback resources, dedicating higher accuracy to strong interference directions and lower accuracy to weaker ones.

[0033] In a further implementation form, reporting the Precoding Matrix Indicator, PMI (JP k), requires bP kbits and reporting the Interference Matrix Indicator, IMIk), requires bt kbits, where bt k< bP k. By allocating more bits to the preferred precoding PMI (JP k), which directly affects data transmission quality, the communication apparatus ensures higher-resolution feedback for critical data-carrying directions. Simultaneously, fewer bits are allocated to the interference-related directions IMI

[0034]

[0035] k), which require lower accuracy since they primarily inform scheduling and interference avoidance decisions.

[0036] In a further implementation form, the first communication apparatus is further configured to perform precoding for a (sub)band, the precoding comprising avoiding the interfering directions indicated by the IMIs JI ltJI 2, — ilk, ■■■

[0037]

[0038] reported by one or more second communication apparatuses comprising the UEs 1,2,

[0039]

[0040] when the IMIs

[0041]

[0042] 1;JI 2, — ilk, ■■■ >! / , / <• indicate interference directions that meet the interference condition of the respective UEs 1, 2,..., fc,..., K. By leveraging the interference directions reported by each UE, the first communication apparatus ensures that its transmission avoids channel directions that meet the interference conditions specific to each UE. This approach enhances the overall communication system performance by reducing signal degradation caused by interference, leading to improved data reliability and throughput for all UEs.

[0043] In a further implementation form, the first communication apparatus is further configured to perform scheduling for a (sub)band by having received PMI

[0044]

[0045] and IMI (7;^) from the UE (UEk) and receiving a PMI lP k!) from another UE (UEk,), comparing the received codewords and if the PMI of (UEk,) is equivalent to the IMI for the UE (UEk) when the interference direction reported by the UE (UEk) is a direction that meets the non-interference condition of the UE (UEk). then the two UEs can be paired in the (sub)band. Equivalence can be for example being equal, that is, JP k’ = 7; kor, for example, having high correlation between the columns of the precoding matrix indicated by JP k’ and the columns of the precoding matrix indicated by 7,k. By comparing the preferred precoder (7P k,) ofoneUE (UEk,) with the interference direction (I k) of another UE (UEk), the communication apparatus ensures that the two UEs can coexist without causing mutual interference, provided the interference direction meets the non-interference condition of the UE (UEk). This approach optimizes resource allocation by maximizing the reuse of time- frequency resources while maintaining high communication quality. The pairing of UEs in this manner reduces interference, enhances spectral efficiency, and improves overall system throughput.

[0046] In a further implementation form, the reference signal comprises at least one pilot, such as a Channel State Information Reference Signal, CSI-RS. Leveraging the use of standardized pilot signals like CSI-RS enhances interoperability across devices and adherence to communication standards, making the first communication apparatus as well as the second communication apparatus scalable and robust for deployment in diverse scenarios.

[0047] In a further implementation form, the first communication apparatus is a Base Station. The base station achieves high spectral efficiency, improved throughput, and better support for diverse user requirements.

[0048] In yet another aspect, there is provided a method for a first communication apparatus, the method comprising transmitting a CSI report configuration message to a second communication apparatus comprising a User Equipment, UE (UEk), the CSI report configuration message comprising an indicator for a performance codebook (CP k) for the UE (UEk) and an indicator for an interference codebook ( / for the UE (UEk). The performance codebook (CP k) is for preferred precoder reporting and the interference codebook ( / is for interference direction reporting. The method further comprises transmitting a referencesignal to the UE (UEk), and receiving a CSI report from the UE (UEk). The CSI report comprising a Precoding Matrix Indicator, PMI (0P k), indicating a performance codeword selected from the performance codebook (CP k) by the UE (UEk) as the UE’s (UEk) preferred precoder from the performance codebook (CPand an Interference Matrix Indicator, IMIk), indicating an interference codeword selected from the interference codebook (Q / J by the UE (UEk), the interference codeword indicating an interference direction, wherein the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction, or a direction that meets a non-interference condition thereby reporting a weak

[0049]

[0050] interference in that direction.

[0051] In a yet another aspect, there is provided a computer program product comprising program instructions for performing the method when executed by one or more processors in the first communication apparatus.

[0052] In a yet another aspect, there is provided a second communication apparatus comprising a UE (UEk) configured to receive a CSI report configuration message, receive a reference signal, estimate a downlink channel Hkbased on information received in the CSI report configuration message and the reference signal and then, compute a PMI (JPand an IMIk), wherein the PMI (JPindicates a performance codeword, selected from a performance codebook (CP k), identifying a preferred precoder of the UE (UEk), and the IMI indicates an interference codeword, selected from an interference codebook (C,fc), indicating an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction. The second communication apparatus comprising the UE (UEk) is further configured to compute the PMI and the IMI based on the estimated downlink channel (Hk). By selecting appropriate codewords from the performance codebook (CP k) and the interference codebook (CI k), the UE can adapt to varying channel conditions.

[0053] In yet another aspect, there is provided a method for the second communication apparatus comprising the UE (UEk), the method comprises receiving a CSI report configuration message, receiving a reference signal, and estimating a downlink channel (Hk) based on information received in the CSI report configuration message and the reference signal. The method further comprises computing a PMI (JP k) and an IMI where the PMI indicates a performance codeword, selected from a performance codebook (CP k), identifying a preferred precoder of the UE (UEk), and the IMI indicates an interference codeword, selected from an interference codebook (C; k), indicating an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction, or a direction that meets a non-interference condition thereby reporting a weak interference in that direction. The method further comprises computing the PMI CJP k) and the IMI based on the estimated downlink channel (Hk). The PMI selects the best precoder, while the IMI identifies the interference direction, allowing the UE to report strong or weak interference. This approach enables

[0054]

[0055] dynamic adaptation to channel conditions, improving communication efficiency and reliability.

[0056] In a yet another aspect, there is provided a computer program product comprising program instructions for performing the method when executed by one or more processors in a second communication apparatus. By utilizing program instructions that can be executed by one or more processors in the second communication apparatus, the second communication apparatus enables efficient execution of the method without the requirement for specialized hardware. This approach allows for easier updates and adaptations of the method through software, ensuring that the UE comprised by the second communication apparatus can dynamically adjust to evolving communication requirements and standards.

[0057] It is to be appreciated that all the aforementioned implementation forms can be combined.It has to be noted that all devices, elements, circuitry, units, and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

[0058] Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

[0061] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

[0062] FIG. 1A is a network environment diagram of a communication system comprising a first communication apparatus and a second communication apparatus comprising a User Equipment (UE), in accordance with an embodiment of the present disclosure;

[0063] FIG. IB is a block diagram that illustrates various exemplary components of a first communication apparatus, in accordance with an embodiment of the present disclosure;

[0064] FIG. 1C is a block diagram that illustrates various exemplary components of a UE, in accordance with an embodiment of the present disclosure;

[0065] FIG. 2 is a flowchart of a method for a first communication apparatus, in accordance with an embodiment of the present disclosure;

[0066] FIG. 3 is a flowchart of a method for use in a second communication apparatus comprising a UE, in accordance with an embodiment of the present disclosure;

[0067] FIG.4 is a flowchart that depicts Channel State Information (CSI) reporting in a wireless communication system, in accordance with an embodiment of the present disclosure;

[0068] FIG. 5 is a flowchart that depicts CSI reporting in a wireless communication system, in accordance with another embodiment of the present disclosure; and

[0069] FIG. 6 is a flowchart that depicts Channel State Information (CSI) reporting in a wireless communication system, in accordance with yet another embodiment of the present disclosure.

[0070] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.DETAILED DESCRIPTION OF EMBODIMENTS

[0071] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.

[0072] FIG. 1A is a network environment diagram of a communication system comprising a first communication apparatus and a second communication apparatus comprising a User Equipment (UE), in accordance with an embodiment of the present disclosure. Referring to FIG. 1A, there is shown a communication system 100 comprising a first communication apparatus 102 and a second communication apparatus 104 comprising a User Equipment (UE) 104k (UEk). where fc G {1,2,..., K}, where K is a definite number. There is shown only one second communication apparatus (i.e., the second communication apparatus 104 comprising the UE (104fc) in the FIG. 1A, for the sake of simplicity. However, in another implementation scenario, there may be multiple second communication apparatuses, each comprising a UE, and may be configured to communicate with the first communication apparatus 102.

[0073] The first communication apparatus 102 may include suitable logic, circuitry, interfaces and / or code that is configured to transmit a Channel State Information (CSI) report configuration message to the second communication apparatus 104 comprising the UE 104fc, via the communication network 106 (e.g., a propagation channel). Examples of the first communication apparatus 102 may include but are not limited to, a Base Station (BS), an Internet-of-Things (IoT) controller, a server, a transceiver, customized hardware for wireless telecommunication, or any other portable or non-portable electronic device. The first communication apparatus 102 may have more than one antenna for communication with multiple second communication apparatuses, each comprising a UE.

[0074] The second communication apparatus 104 comprises a terminal device, or some component within the terminal device, for example, the UE 104fc, a UE controller (e.g., a processor of the UE 104fc), chip, chipset etc. The second communication apparatus 104 comprising the UE 104fc may include suitable logic, circuitry, interfaces, and / or code that is configured to receive the CSI report configuration message from the first communication apparatus 102. Examples of the UE 104fc may include, but are not limited to, a smart phone, a laptop, a tablet, an Intemet-of- Things (loT) device, a machine type communication (MTC) device, a computing device, a server, a drone, customized hardware for wireless telecommunication, a transceiver, or any other portable or non-portable electronic device.

[0075] The communication network 106 includes a medium, such as a communication channel, through which the first communication apparatus 102 potentially communicates with the second communication apparatus 104 comprising the UE 104fc. Examples of the communication network 106 may include, but are not limited to, a cellular network (e.g., a 5G, or 5G NR network, such as sub 6 GHz, cmWave, or mmWave communication network), a cloud network, a Local Area Network (LAN), a vehicle- to-network ( V2N) network, a Metropolitan Area Network (MAN), and / or the Internet.

[0076] FIG. IB is a block diagram that illustrates various exemplary components of a first communication apparatus, in accordance with an embodiment of the present disclosure. FIG. IB is described in conjunction with elements from FIG. 1 A. With reference to FIG. IB, there is shown a block diagram 100B that illustrates various exemplary components of the first communication apparatus 102. The first communication apparatus 102 includes a plurality of antennas 108, a memory 110, and a processor 112.

[0077] Each of the plurality of antennas 108 may include suitable logic, circuitry, and / or interfaces that are configured to transmit the CSI report configuration message to the second communication apparatus 104 comprising the UE 104fc. In line with currentwireless standards, the first communication apparatus 102 features a configuration with multiple antennas (i.e., the plurality of antennas 108) to achieve optimal bandwidth usage and improved network efficiency. The plurality of antennas 108 would facilitate the transmission of the CSI report configuration message and a reference signal from the first communication apparatus 102 to the second communication apparatus 104 comprising the UE 104k, and reception of a CSI report from the second communication apparatus 104 comprising the UE 104k at the first communication apparatus 102. Examples of each of the plurality of antennas 108 may include but are not limited to, a radio frequency transceiver, a network interface, a telematics unit, or any antenna suitable for use in a base station or other portable or non-portable communication devices. The plurality of antennas 108 may wirelessly communicate by use of various wireless communication protocols.

[0078] The memory 110 may include suitable logic, circuitry, and / or interfaces that is configured to store machine code and / or instructions executable by the processor 112. Examples of implementation of the memory 110 may include, but are not limited to, an Electrically Erasable Programmable Read-Only Memory (EEPROM), Random Access Memory (RAM), Read Only Memory (ROM), Hard Disk Drive (HDD), Flash memory, a Secure Digital (SD) card, Solid-State Drive (SSD), a computer readable storage medium, and / or CPU cache memory. The memory 110 may store an operating system and / or a computer program product to operate the first communication apparatus 102. A computer readable storage medium for providing a nontransient memory may include, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing.

[0079] The processor 112 may include suitable logic, circuitry, and / or interfaces that are configured to execute instructions stored in the memory 110. Examples of the processor 112 may include, but are not limited to an integrated circuit, a co-processor, a microprocessor, a microcontroller, a complex instruction set computing (CISC) processor, an application-specific integrated circuit (ASIC) processor, a reduced instruction set (RISC) processor, a very long instruction word (VLIW) processor, a central processing unit (CPU), a state machine, a data processing unit, and other processors or circuits. Moreover, the processor 112 may refer to one or more individual processors, processing devices, or a processing unit that is part of a machine.

[0080] FIG. 1C is a block diagram that illustrates various exemplary components of a UE, in accordance with an embodiment of the present disclosure. FIG. 1C is described in conjunction with elements from FIGs. 1A and IB. With reference to FIG. 1C, there is shown a block diagram 100C that illustrates various exemplary components of the UE 104fc. The UE 104fc includes a plurality of antennas 114, a memory 116, and a processor 118. In the present disclosure, the UE 104fcis represented as a kth UE (i.e., UE.

[0081] Each of the plurality of antennas 114 may include suitable logic, circuitry, and / or interfaces that are configured to receive a CSI report configuration message from the first communication apparatus 102 and transmit a CSI report to the first communication apparatus 102. Examples of each of the plurality of antennas 114 may include, but are not limited to, a radio frequency transceiver, a network interface, a telematics unit, or any antenna suitable for use in the UE 104fc or other portable or non-portable communication devices. Each of the plurality of antennas 114 may wirelessly communicate by use of various wireless communication protocols.

[0082] The memory 116 may include suitable logic, circuitry, and / or interfaces that is configured to store machine code and / or instructions executable by the processor 118. Examples of implementation of the memory 116 are the same as that of the memory 110 of the first communication apparatus 102.

[0083] The processor 118 may include suitable logic, circuitry, and / or interfaces that is configured to execute instructions stored in the memory 116. Examples of implementation of the processor 118 are similar to that of the processor 112 of the first communication apparatus 102.In operation, the first communication apparatus 102 is configured to transmit a CSI report configuration message to the second communication apparatus 104 comprising the UE 104k. The CSI report configuration message comprises an indicator for a performance codebook (CP k) for the UE 104k (UEk) and an indicator for an interference codebook (C / fc) for the UE 104fc (UEk), where the performance codebook (CP k) is for preferred precoder reporting and the interference codebook ( C / fc) is for interference direction reporting. The performance codebook (CP k) enables the UE 104fc (UEk) to identify and report the most suitable data transmission directions to the first communication apparatus 102, ensuring efficient data communication by minimizing signal degradation and improving throughput. The interference codebook (CI k) allows the UE 104fc (UEk) to report channel directions associated with interference, either to highlight directions that other UEs should avoid (means strong interfering directions) or to identify directions that cause minimal interference (means weak interfering directions). The UE 104fc (UEk) is configured to utilize the performance codebook (CP k) for computing strong and preferred directions for data communication. The computed preferred directions for data communication are then, transmitted to the first communication apparatus 102, which is known as the preferred precoder reporting (may also be referred to as Precoding Matrix Indicator (PMI), reporting). The preferred precoder reporting is used to enhance data signal quality and reduce interference in data transmission in a downlink channel communication. The interference direction reporting (may also be referred to as Interference Matrix Indicator (IMI) (? / , / <) reporting) may be referred to as the process by which the UE 104fc (UEk) identifies and communicates channel directions associated with interference conditions to the first communication apparatus 102 thus, enabling the first communication apparatus 102 to manage and mitigate signal interference for improved network performance. The transmission of the performance codebook (CP k) and the interference codebook (CI k) to the UE 104fc (UEk) enables the UE 104fc to precisely compute the preferred directions (identified by the PMI, ('Ji>kj) for data transmission and interfering directions (identified by the IMI,

[0084]

[0085] )) which are required to be considered or not depending on their interference conditions during communication with multiple UEs. This further leads the first communication apparatus 102 to efficiently determine the UE's channel conditions, and perform precise scheduling and precoding for the UE 104fc.

[0086] In addition to the performance codebook (CP k) and the interference codebook (CI k), the CSI report configuration message can have other information, for example, as defined in the Third Generation Partnership Project (3GPP) Fifth Generation (5G) New Radio (NR) Standard, where the standard’s CSI report configuration message includes fields like carrier, cqi-BitsPerSubband, and others. A new field or fields can be added to the CSI report configuration message in order to instruct the UE 104fc (UEk) to use two codebooks, the performance codebook (CP k) for preferred precoder reporting, and the interference codebook (C; / <) for interference reporting.

[0087] In accordance with an embodiment, the CSI report configuration message includes an indicator for a strong interference codebook (C’; ] fc) and an indicator for a weak interference codebook (CI2 k). The strong interference codebook (CIl k) enables theUE 104fc (UEk) to identify and report directions that meet an interference condition, representing areas of strong interference that should be avoided while communicating with other UEs. The weak interference codebook (C;2 k) allows the UE 104fc (UEk) to report directions that meet a non-interference condition, representing areas of weak interference that can be safely utilized while communicating with other UEs. By incorporating the indicators for strong and weak interferences in the CSI report configuration message, the first communication apparatus 102 equips the UE 104k (UEk) with the tools to provide detailed feedback on the interference landscape. The dual-codebook (i.e., the strong interference codebook (CIl k) and the weak interference codebook (C / 2, / c)) approach enables the first communication apparatus 102 to dynamically adjust scheduling and precoding strategies, minimizing interference and maximizing spectral efficiency. The inclusion of the strong interference codebook (CIl k) and the weak interference codebook (CI2 k) ensures precise interference management, improving the reliability and performance of multi-user MIMO systems in diverse network conditions.In accordance with an embodiment, the CSI report configuration message includes the interference condition and / or the noninterference condition. The interference condition may be used to identify those directions where strong interference exists, about which the UE 104k (UEk) can be configured to inform the first communication apparatus 102 to avoid these directions during scheduling and precoding. Similarly, the non-interference condition may be used to identify directions with minimal or no interference, allowing the first communication apparatus 102 to utilize such directions effectively for other UEs without any interference. By including the interference conditions and / or the non-interference condition in the CSI report configuration message, the first communication apparatus 102 ensures that the UE 104k (UEk) is equipped to provide precise feedback on the interference landscape. This information enables the first communication apparatus 102 to adjust its transmission strategy dynamically, minimizing interference and maximizing resource allocation.

[0088] Moreover, the interference condition and non-interference condition can be rigorously defined based on specific metrics, computed and evaluated at the UE 104fc (UEk). For strong interference, a metric Msmay be defined, with the interference direction deemed strong when the metric Msmeets a certain threshold value. For instance, strong interference may occur when the interference direction results in power that exceeds a defined threshold value or in a signal-to-interference ratio that falls below a specified threshold value. Conversely, weak interference (or non-interference) direction is characterized by a metric Mw, where the interference direction is considered weak if the metric Mwsatisfies specific criteria. For example, weak interference occurs when the interference direction results in power that is below a certain threshold value or in a signal-to-interference ratio that surpasses a defined limit. In the context of reporting scenarios, the UE 104fc identifies and reports these directions, including preferred directions, strong interfering directions, and / or weak (non-interfering) directions, ensuring effective directionality-based communication.

[0089] In accordance with an embodiment, the performance codebook (CP k) has an accuracy that is higher than an accuracy of the interference codebook (C; k). The higher accuracy of the performance codebook (CP k) ensures that the UE 104fc (UEk) can precisely report its preferred precoding directions (or the PMI, (JPtk)), which have significance for maximizing the data transmission efficiency and signal quality. While, the interference codebook (C; k), which is used to report interference directions (or the IMI, ( / / , / <). I. has lower accuracy. The interference directions primarily indicate general interference patterns rather than precise transmission paths. The allocation of accuracy reflects the relative importance of the two codebooks: the performance codebook (CP k) directly influences the data-carrying directions, requiring greater precision, while the interference codebook (C; k) focuses on managing interference with less stringent accuracy requirements. By prioritizing the accuracy of the performance codebook (CP k), the first communication apparatus 102 can allocate more feedback bits to represent strong and preferred transmission directions, ensuring reliable data delivery. For example, if bP kbits are used for the performance codebook and bI kbits for the interference codebook, the first communication apparatus 102 maintains bP k> bI kto ensure reliable data communication.

[0090] In accordance with an embodiment, the performance codebook (CP k) is the Type II codebook as defined in 3GPP 5G NR standard. The Type II codebook is designed with greater accuracy and finer granularity, making the Type II codebook ideal for capturing the channel directions which can be used for efficient and reliable data communication to the UE 104fc (UEk). The Type II codebook plays a significant role in various communication standards and protocols, such as those used in cellular networks and digital audio / video transmission systems, by providing a structured CSI feedback framework. By utilizing the Type II codebook, the first communication apparatus 102 can receive detailed feedback from the UE 104k (UEk) about its preferred precoder, and accordingly align data transmissions with the UE’s channel conditions. The use ofthe Type II codebook as the performance codebook (CP k) ensures that the data-carrying directions are represented with high fidelity, enabling thefirst communication apparatus 102 to perform effective scheduling and precoding, thereby enhancing overall network performance and minimizing inter-user interference.

[0091] In accordance with an embodiment, the interference codebook (C / fc) is the Type II codebook when reporting strong interference, and the Type I codebook, as defined in 3GPP 5G NR standard, when reporting weak interference. The Type II codebook refers to a set of predefined codewords used in the context of signal processing and communications, particularly in the field of wireless communication systems. The Type II codebook, with its higher accuracy and finer granularity, is employed for strong interference reporting to provide precise details about directions that can significantly degrade data communication and must be avoided when communication with other UEs (or users). The Type I codebook, as defined in 3GPP 5G NR standard, which is less complex and requires fewer feedback bits, is used for weak interference reporting, as such conditions do not demand high precision and represent directions that can be safely utilized by other UEs. By adapting the choice of codebook (i.e., the Type I codebook and the Type II codebook) to the type of interference (i.e., strong interference and weak interference), the first communication apparatus 102 leads to an efficient resource allocation, dedicating more feedback accuracy to critical interference scenarios while conserving resources for less impactful conditions.

[0092] In accordance with an embodiment, the interference codebook (C; k) is the Type I codebook. The Type I codebook is designed with lower complexity and granularity compared to the Type II codebook, making the Type I codebook suitable for identifying interference patterns without requiring excessive feedback overhead. By using the Type I codebook for the interference codebook (C; k), the UE 104k (UEk) can efficiently report directions of strong interference, which should be avoided, and weak interference as well, which can be safely utilized during communication with other UEs. This approach ensures that the first communication apparatus 102 receives sufficient information to manage interference effectively while maximizing resource allocation for data communication. The use of the Type I codebook reduces the number of feedback bits required for interference reporting, enabling the communication system 100 to allocate more resources to the higher accuracy of the performance codebook (CP k) for preferred precoding directions.

[0093] In accordance with an embodiment, the strong interference codebook l'C)i, / <) is a Type II codebook and the weak interference codebook (CI2 k) is a Type I codebook. The Type II codebook is chosen for the strong interference codebook l'C)i, / <) because it provides higher accuracy and finer granularity, making it well-suited for capturing strong interference directions that require precise reporting to avoid any kind of interference during data transmission to theUE 104k (UEk). On the other hand, the Type I codebook is selected for the weak interference codebook (CI2 k) due to its lower complexity, which is sufficient for identifying weak interference directions that can be safely utilized without causing performance degradation. By leveraging these distinct codebook types (i.e., Type II codebook and Type I codebook), the first communication apparatus 102 achieves an efficient balance between reporting accuracy and CSI feedback overhead, enabling an effective scheduling and precoding.

[0094] The present disclosure implements a dual-codebook reporting system that comprehensively captures both preferred and interference directions. In one scenario, the performance codebook (CP k) used for reporting the preferred precoder by the UE 104fc (UEk) is configured as a Type II codebook, while the interference codebook (C; k), used for reporting interference directions, is configured as a Type I codebook. In another scenario, the interference codebook (C; k) is configured as a Type II codebook when the UE 104fc (UEk) reports strong interference directions and as a Type I codebook when the UE 104fc (UEk) reports weak interference directions.

[0095] In accordance with an embodiment, the first communication apparatus 102 is a Base Station. In said implementation scenario of the communication system 100, the first communication apparatus 102 is the base station. However, in anotherimplementation scenario, the first communication apparatus 102 may be a network device controller, for example, an Internet-of-Things (IoT) controller, a server, and the like.

[0096] The first communication apparatus 102 is further configured to transmit a reference signal to the UE 104k (UEk). The reference signal, typically known as a Channel State Information Reference Signal (CSI-RS) in the 3GPP 5G NR standard, serves as a fundamental pilot signal that enables the UE 104k (UEk) to precisely compute the channel estimation (i.e., downlink channel estimation). The transmission of the reference signal to the UE 104fc (UEk) enables the UE 104fc (UEk) to measure and estimate the downlink channel (may also be represented as Hk) characteristics.

[0097] In accordance with an embodiment, the reference signal comprises at least one pilot, such as a Channel State Information Reference Signal (CSI-RS). The reference signal (CSI-RS) is a pilot signal transmitted by the first communication apparatus 102 (e.g., a Base Station (BS)) that enables the UE 104fc to measure and estimate its downlink channel (Hk). The reference signal is standardized in 3GPP 5G NR and serves as the basis for the UE 104fc to compute both its Precoding Matrix Indicator (PMI) and Interference Matrix Indicator (IMI) feedback. The CSI-RS transmission precedes the UE's CSI reporting and is used for accurate channel estimation.

[0098] The first communication apparatus 102 is further configured to receive a Channel State Information, CSI, report from the UE 104fc (UEk). The CSI report comprises a Precoding Matrix Indicator, PMI (0P k), indicating a performance codeword selected from the performance codebook (CP k), by the UE 104fc (UEk) as the UE’s (UEk) preferred precoder from the performance codebook (CP k) and an Interference Matrix Indicator, IMI!7; k). indicating an interference codeword selected from the interference codebook (C; k), by the UE 104fc (UEk), the interference codeword indicating an interference direction. The interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction. Upon reception of the reference signal and based on the information received in the CSI report configuration message, the UE 104fc (UEk) is configured to compute the PMI (0P k) and IMI!7; k). The PMI (0P k) indicates a codeword, selected from performance codebook (CP k), that the UE 104fc (UEk) identifies as its preferred precoder. The IMI!7; k) indicates a codeword, selected from interference codebook (C; k), that the UE 104A (UEk), identifies as representative interference directions. For the PMI (7pjk) computation, the UE 104fc (UEk) selects a codeword from the performance codebook (CP k) which represent the preferred directions for data transmission. Similarly, for the IMI (J; k), the UE 104fc (UEk) selects a codeword from the interference codebook (C; k) which represents the interfering directions including either strong interfering directions or weak interfering directions. Such CSI feedback is provided by the UE 104fc (UEk) to the first communication apparatus 102 leading t

[0099]

[0100] o efficient data communications, particularly, in MU-MIMO communication systems.

[0101] For example, in downlink Multi-User (MU) Multiple Input Multiple Output (MIMO) antenna communications, the first communication apparatus 102 (i.e., the BS) with the plurality of antennas 108 performs scheduling and precoding in order to communicate data to one or more second communication apparatuses comprising one or more UEs, each with one or more antennas. The scheduling and precoding include selecting, for each time-frequency resource (e.g., each Resource Block (RB)), a subset of K UEs to be served by the first communication apparatus 102, selected out of the total K UES, and computing the precoding matrix P for serving the K UEs. The received signal ykE CMfcX1at a fcth UE (i.e., the UE 104fc) for a given timefrequency resource can be written in form of Equation (1)

[0102] yk= HkPx + nk(1)where, HkCMtX,vis the channel from the first communication apparatus 102 to the UE 104k (i.e., UEk), Mkis the number of receiver antennas at the UE 104k (i.e., UEk), and N is the number of transmitter antennas at the first communication apparatus 102 (i.e., the BS), nkG CMfcX1is additive noise, P = [P1;P2,..., P;f| G C, Vxiw=i '■< where PkG CWXL'cis the precoder for the UE 104fc (i.e., UEk) assigning Lklayers (i.e., data streams)to the UE 104fc (i.e., UEk), andx = [x1;x2,...,x;f|TG C^=iLfcxl;where xkG ClxLtis the vector of Lkdata streams for the UE 104fc (i.e., UEk). For example, the precoding and scheduling performed by the first communication apparatus 102 (i.e., the BS) can aim at having HkPk, = 0 for fc fc', which means that there is no inter-user interference, and at optimizing a performance metric, like spectral efficiency or sum rate at high SNR. As such, having at the first communication apparatus 102 (i.e., the BS) CSI about the downlink channel (Hk) for each UE aids the first communication apparatus 102 (i.e., the BS) in computing the precoder and performing scheduling. In order to obtain the CSI feedback from the UE 104fc (UEk), the first communication apparatus 102 firstly transmits the CSI report configuration message to the second communication apparatus 104 comprising the UE 104fc followed by transmitting the reference signal to the second communication apparatus 104 comprising the UE 104fc. Upon reception of the CSI report configuration message and the reference signal, the UE 104fc is configured to compute the PMI (JP k) and IMI (J; k) based on the estimated downlink channel. The downlink channel for a subband estimated at the UE 104fc (UEk) may be represented as HkG CMk*N, where the subband can include multiple Physical Resource Blocks (PRBs) and thus, multiple subcarriers. The UE 104fc (UEk) is configured to compute the PMI (JP k) and the IMI (J; k) based on Singular Value Decomposition (SVD) of the estimated downlink channel, Hk= UkDkV”. where the singular values in the diagonal matrix (Dk) are arranged in descending order. For the PMI computation, the UE 104fc (UEk) is configured to select a codeword from the performance codebook that best represents the first Lksingular vectors in Vk, which correspond to the strongest singular values and represent the preferred directions for data transmission. Thus, an optimization problem can be formulated to find the preferred precoder as W3p= arg max fi Clsfc. Wj), where \rs kare the singular vectors corresponding to the strongest singular values, and f\ is an WjeCp.fc ' objective function that aims at finding a codeword W from CP kthat captures well the strong directions identified by Vs k.

[0103] The IMI (JI k) can be computed based on the Lk+ 1 to L'kcolumns of Vkwhere L'k> Lk. This is the case for strong interference reporting where the interference condition is that the directions with a singular value weaker than the Lk-th strongest singular value and stronger than the L'k-th strongest singular value are the ones reported. Thus, the metric Msis the strength of the singular value and this is used to identify the Lk+ 1 to L'kcolumns of Vkwhich are singular vectors that correspond to singular values that are weaker than the first Lksingular values and capture directions that possibly cannot be used for sending data to the UE 104fc (UEk). However, these Lk+ 1 to L'kcolumns of Vkprovide information that can be very useful for the first communication apparatus 102 (i.e., the BS), since these are singular vectors that represent directions which may possibly result in strong interference to the UE 104fc (UEk), when used to transmit data streams to other UEs different than UE 104fc (UEk). ThusW3 / fc= arg^rnax where V; kare the Lk+ 1 to L'kcolumns of Vkand / 2describes an objective function that aims at choosing an IMI from the interference codebook (C; k) that captures well the interfering directions identified by NI k. The performance codebook (CP k) and the interference codebook (C; k) are chosen such that the performance codebook (CP k) provides a higher accuracy for representing the strong and preferred directions for data transmission than the accuracy provided by the interference codebook (C; k). Hence, the number of bits of feedback bP krequired for reporting the PMI CJP k) is larger than the number of bits of feedback bI krequired for reporting the IMI (J; k). The total feedback overhead is optimized by allocating more bits (bP fc) to the PMI reporting than to the IMI reporting (b,fc) reflecting the higher significance of accurate preferred direction reporting. Thereafter, the first communication apparatus 102 (i.e., the BS) can use this comprehensive CSI feedback to perform efficient scheduling and precoding, either avoiding interference between multiple UEs (in case of strong

[0104]

[0105] interference reporting) or enabling frequency reuse (in case of weak interference reporting).In accordance with an embodiment, the CSI Report includes one PMI, (3P k), and one IMI, (3I k), per (sub)band utilized. The (sub)band refers to a specific frequency range within the overall bandwidth, often used in the context of dividing the available spectrum into smaller segments for more efficient signal processing or allocation. The PMI represents a codeword selected from the predefined performance codebook (CP k) that closely matches the strongest singular vectors of the estimated downlink channel (Hk) matrix. The PMI (P k) identifies the preferred precoding direction for the UE 104k (UEk), enabling the first communication apparatus 102 to align the data transmissions with the strongest and most efficient channels for reliable communication. The IMI (I k), indicates interference-related directions, distinguishing between strong interference directions which are to be avoided and weak interference directions that other UEs can be utilized without causing disruption. Strong interference directions represent channel directions where signal transmission from other UEs would cause significant interference to the UE 104k. The weak interfering directions represent channel directions that are minimally impacted by interference and can be reused by other UEs. By associating one PMI (P k) and one IMI (I k) with each (sub)band, the UE 104fc (UEk) ensures detailed and precise feedback tailored to the varying channel conditions of each frequency band.

[0106] In accordance with an embodiment, reporting the Precoding Matrix Indicator, PMI

[0107]

[0108] requires bP kbits and reporting the Interference Matrix Indicator, IMI

[0109]

[0110] requires bt kbits, where bt k< bP k. The allocation of more bits (bP k) to the PMI (5P fc) ensures finer granularity in representing the preferred precoding directions, enabling precise alignment of the data transmission in the strong preferred directions leading to reliable and effective data communication. While, fewer bits (bI k) are allocated for the IMI

[0111]

[0112] as it primarily conveys interference-related directions, which do not require the same level of precision which is required for data transmission. This balance minimizes feedback overhead while ensuring accurate representation of required information to the first communication apparatus 102.

[0113] In accordance with an embodiment, the first communication apparatus 102 is further configured to receive the Interference Matrix Indicator, IMI (JI k) by receiving a first Interference Matrix Indicator, IMI (Jn k), indicating a first interference direction being a direction that meets the interference condition, the first IMI thereby reporting a strong interference direction. The first communication apparatus 102 is further configured to receive the Interference Matrix Indicator, IMI (I k) by receiving a second Interference Matrix Indicator, IMI (I2tk), indicating a second interference direction being a direction that meets the noninterference condition, the second IMI thereby reporting a weak interference direction. The interference condition refers to a situation in which undesired electromagnetic signals disrupt the proper functioning of electronic devices or systems, leading to degradation or loss of performance, data corruption, or malfunction. Specifically, the first communication apparatus 102 receives the first IMI (Il k) that identifies the direction meeting the interference condition, referred to as a strong interference direction. The first IMI (Il k) identifies strong interfering channel directions where interference can be significant and should be avoided during scheduling and precoding. The second IMI (J / 2,fc) highlights weak interfering channel directions with minimal interference that can safely be used during scheduling and precoding. By distinguishing between strong and weak interference directions, the first communication apparatus 102 can effectively minimize interference, maximize spectral efficiency, and enhance the reliability of multi-user MIMO communications. The interference conditions and non-interference conditions have already been described.

[0114] In accordance with an embodiment, the first communication apparatus 102 is further configured to perform scheduling and / or computing a precoder based on the Interference Matrix Indicator, IMI (I k), and the Precoding Matrix Indicator, PMI (P k). The first communication apparatus 102 is configured to utilize the reported PMI (P k) and the IMI

[0115]

[0116] received from the UE 104fc (UEk) in the CSI report. The CSI report may also include additional information, such as Channel Quality Indicator (CQI) and Rank Indicator (RI), as specified in the 3GPP 5G NR standard. The CSI Report of each UE can include information for one or multiple sub(bands). If multiple sub(bands) are reported from the UE 104fc (UEk) then, the CSI Report can include a reported PMI (JPand IMI per subband. This allows the first communication apparatus 102 to have value of the PMI(JP k) and IMI!7; k) for each (subjband. The first communication apparatus 102 can use this received information for performing the scheduling or computing the precoder, or both. An example of computing the precoder is as follows. Assuming that other UEs may be configured to use the same codebooks hence CP k= CPand CI k= C:then the first communication apparatus 102 can be configured to compute, for a (subjband, for each UE, the following matrices defined in Equation (2) and Equation (3)

[0117] Vs ffc1= [ LWJ, P,i, W,. W, „, W, „. W, 1 (2)

[0118]

[0119] = [wvwJ;2.. wJlK] (3)

[0120] Where, the matrix, Vsin Equation (2) comprises the reported preferred precoders from all UEs except the UE 104k (UEk) and the matrix, V;

[0121]

[0122] in Equation (3) represents directions that the UE 104k (UEk) should also avoid in order to prevent generating interference to other users. The precoder for the UE 104fc (UEk) is aimed at transmitting the signal to the UE 104fc (UEk) based on its preferred reported precoder W3p tand at the same time avoid creating interference to other UEs. This is achieved by avoiding sending data on directions that interfere with other users and which are identified by Vsand V;

[0123]

[0124] . The first communication apparatus 102 computes the precoder for the UE

[0125]

[0126] 104fc (UEk) as Pk= / preCt(W3pwhere fprec,. isafunction that computes the precoder for the UE 104fc (UEk) based on the preferred directions and interfering directions as identified at the first communication apparatus 102 based on the PMIs (P k) and IMIs (I k) reported by the UEs.

[0127] In accordance with an embodiment, the first communication apparatus 102 is further configured to perform precoding for the (subjband, where the precoding comprising avoiding the interfering directions indicated by the IMIs (I 1, JI 2, ■■■,'pk’ ■■■ -3I, K) reported by one or more second communication apparatuses comprising the UEs (1, 2,...,fc,

[0128]

[0129] when the IMI (Jz l,

[0130] , JI K) indicate interference directions that meet the interference condition of the respective UEs (1,2,..., fc,..., k). When the UE 104fc (UEk) reports the IMI!7; k) indicating interference directions that meet the interference condition, these directions are identified as the directions where strong interference is likely to occur. The first communication apparatus 102 utilizes such CSI feedback to ensure that these directions are required to be avoided while performing scheduling or precoding, thereby preventing inter-user interference and enhancing the quality of transmissions for all the UEs. By dynamically adjusting the precoding to avoid these interference-prone directions, the first communication apparatus 102 ensures efficient utilization of spectral resources and leads to an improved overall network performance.

[0131] Both PMI (P k) and IMI (I k) can be computed for example per (sub)band based on the downlink channel Hke CM'<X, Vestimated for the (subjband. For the case where weak interference directions are reported, the IMI (Jz fc) for the (sub)band can also be computed based on the SVD of the estimated downlink channel, Hk= UkDkV” by computing W3= arg max f3(yweak,k^i where weak,k are the Lkcolumns of Vkthat correspond to the Lkweakest singular values in Dkand f3describes an objective function that aims at choosing an IMI (3I k) from the interference codebook ( / that captures well the weak interfering directions identified by Vweak k. In this example of weak interference reporting the non-interference condition corresponds to having a weak singular value (a singular value within the Lkweakest), hence, the metric Mwis the strength of the singular value and the directions that correspond to the Lkweakest singular values are the ones identified as weak interference directions through Vweak k.

[0132] In accordance with an embodiment, the first communication apparatus 102 is further configured to perform scheduling for a (subjband by having the received PMI (JP k) and the IMI (J; k) from the UE 104fc (UEk) and receiving a PMI (JP k'j from another UE (UEk,j, comparing the received codewords and if the PMI of the other UE (UEk,j is equivalent to the IMI for theUE 104k (UEk) when the interference direction reported by the UE 104k (UEk) is a direction that meets the non-interference condition of the UE 104fc (UEk), then the two UEs can be paired in the (sub)band. If the interference direction indicated by the IMI of the UE 104fc (UEk) meets the non-interference condition of the UE 104fc (UEk) and is equivalent to the PMI (7;) k') from the other UE (UEk,), the first communication apparatus 102 may be configured to conclude that UE 104fc (UEk) and the other UE (UEk,) are compatible for pairing, allowing the UE 104fc (UEk) and the other UE (UEk,) to be paired in the same (sub)band. Equivalence can be for example being equal, that is, JP k, =

[0133]

[0134] kor, for example, having high correlation between the columns of the precoding matrix indicated by JP k, and the columns of the precoding matrix indicated byk. This pairing strategy ensures efficient utilization of spectral resources by enabling simultaneous data transmission for both UEs without any mutual interference.

[0135] Moreover, the CSI report from the UE 104fc (UEk) including the selected PMI (3P k) and IMI (Jz k) is received at the first communication apparatus 102. If multiple (sub)bands are reported from the UE 104fc (UEk), then the CSI Report can include a reported PMI (JP k) and IMI (Jz fc) per (sub)band. This allows the first communication apparatus 102 to have the value of the PMI (JP k) and the IMI (Jz fc) for each (sub)band. The first communication apparatus 102 can use this received information for performing the scheduling or computing the precoder, or both. An example of how to perform scheduling for a (sub)band is as follows. This is assumed that, for the (sub)band, the UE 104fc (UEk) has fed back to the first communication apparatus 102, the PMI = -i from a Type II codebook CP k= CTypen as its preferred precoder, and has fed back the IMI (J; k) = from a Type I codebook CI k= CTypei as a low interference precoder. This is also assumed that, for the (sub)band, the other UE (UEk,) has fed back the PMI (JP k!) = -^ from the Type I codebook CP k' = CTypeIas its preferred precoder. It is noticed that the codebooks used by the UEs for preferred precoder reporting are different (CP k+ CP ki), but that the codebook used by the UE 104fc (UEk) for weak interference reporting is the same as the codebook used by the other UE (UEk,) for preferred precoder reporting (Cl k= CP k' = CTypeI). Since, based on the proposed CSI reporting, the first communication apparatus 102 is informed that the PMI JPi k’) = from CTypeIis a preferred precoder for the other UE (UEk,) and is a weak interference precoder for the UE 104fc (UEk) (not creating interference to the UE 104fc (UEk)), then the first communication apparatus 102 may be configured to pair both the UEs (i.e., the UE 104fc (UEk) and the other UE (UEk,)) in the same (sub)band. Thus, it is shown that the mixed codebook reporting may be used to report strong and weak interference directions which facilitates co-scheduling of UEs that have different accuracy reporting (using different codebooks) for reporting their preferred precoders (or preferred directions). To further facilitate the task, the first communication apparatus 102 can keep a look up table of pairable codewords and UEs, as shown in Table 1.

[0136] Table 1: Pairing of UEs

[0137] UE Reported preferred precoder Reported weak interfering precoder Pairable UE(s)

[0138] k Wi kr

[0139] krwzk

[0140]

[0141] In accordance with an embodiment, the second communication apparatus 104 is configured to receive the CSI report configuration message, receive a reference signal, estimate a downlink channel (Hk) based on information received in the CSIreport configuration message and the reference signal and then, compute a PMI (JP k) and an IMI (J; k), where the PMI (3P k') indicates a performance codeword, selected from a performance codebook (CP k), identifying a preferred precoder of the UE 104k (UEk), and the IMI (J; k) indicates an interference codeword, selected from an interference codebook (C; k), indicating an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction, where the second communication apparatus 104 is further configured to compute the PMI (^P k) and the IMI (J; k) based on the estimated downlink channel (Hk). By virtue of comprising the UE 104k, the second apparatus 104 is able to perform all the functions which are performed by the UE 104fc, such as receiving the CSI report configuration message from the first communication apparatus 102, receiving the reference signal from the first communication apparatus 102 and transmitting the CSI report to the first communication apparatus 102.

[0142] Thus, the first communication apparatus 102 optimizes channel state feedback using an innovative dual-codebook reporting framework. The first communication apparatus 102 implements a comprehensive approach where, each UE (i.e., the UE 104fc, (UEk)) is configured to use two distinct codebooks, such as the performance codebook (Cp k) for reporting preferred precoding directions and the interference codebook (CI k) for reporting interference conditions. The first communication apparatus 102 is further configured to send the CSI report configuration message to each UE (i.e., the UE 104fc, (UEk)), configuring both codebooks while allocating more feedback bits (bP k) to the preferred precoding directions than to the interference directions (bjk) ensuring higher accuracy where the accuracy matters the most. Upon receiving reference signals, the UE 104fc, (UEk) is configured to respond with the CSI report comprising both the PMI (Jp k) and the IMI (J; k). The PMI, selected from the performance codebook, identifies the UE's preferred precoder, while the IMI, selected from the interference codebook, can flexibly report either strong interfering directions that other UEs should avoid or weak interfering directions that other UEs can safely use. This dual-codebook approach enables the first communication apparatus 102 to support UEs with different rate requirements using different codebooks, while maintaining efficient CSI feedback overhead. The first communication apparatus 102 can then, leverage this comprehensive CSI feedback to perform more effective scheduling and precoding decisions, particularly in scenarios where multiple UEs required to be paired in the same frequency resources. The solution's compatibility with existing 3GPP standard codebooks, such as using Type II codebooks for preferred directions and Type I codebooks for interference reporting, facilitates practical implementation in current and future wireless networks.

[0143] FIG. 2 is a flowchart of a method for a first communication apparatus, in accordance with an embodiment of the present disclosure. FIG. 2 is described in conjunction with elements from FIGs. 1A, IB, and 1C. With reference to FIG. 2, there is shown a method 200 that includes steps 202 to 206. The step 202 includes two sub-steps 202A and 202B and the step 206 also includes two sub-steps 206A and 206B. The method 200 is executed by the first communication apparatus 102 (of FIG. 1A).

[0144] The method 200 is provided for enabling the first communication apparatus 102 to manage communication with the second communication apparatus 104 comprising the UE 104fc (UEk), by utilizing advanced codebooks for channel state information (CSI) reporting. The method 200 comprises transmitting a CSI report configuration message to the second communication apparatus 104 comprising the UE 104fc (UEk), which includes indicators for a performance codebook (CP k) and an interference codebook (CI k). The performance codebook (CP k) is designed for preferred precoder reporting (or the PMI reporting), while the interference codebook (CI k) is required for interference direction reporting (or the IMI reporting). Additionally, the method 200 involves transmitting the reference signal to the second communication apparatus 104 comprising the UE 104fc (UEk) and receiving a CSI report that includes a Precoding Matrix Indicator PMI (P k) and an Interference Matrix Indicator IMI (I k). The PMI (P k) indicates a preferred precoder selected by the UE 104fc (UEk) from the performance codebook (CP k), while the IMI (I k) provides information on interference directions by reporting strong interference in directions meeting an interference condition and / or weak interference in directions meeting a non-interference condition. Moreover, the method 200 supportsreceiving multiple IMIs, such as a first IMI (3Il k) indicating strong interference and a second IMI (3I2 k) indicating weak interference. Based on the received PMI (P k) and IMI (I k), the method 200 enables the first communication apparatus 102 to perform scheduling and / or computing precoders for efficient and reliable data communication.

[0145] Referring to FIG. 2, at step 202, the method 200 comprises transmitting a CSI report configuration message to the second communication apparatus 104 comprising the UE 104k (UEk). The step 202 involves the transmission of the CSI report configuration message from the first communication apparatus 102 to the UE 104k (UEk). The transmission of the CSI report configuration message can be executed using a standardized signalling protocol, such as that defined by the 3GPP 5G NR standard, which allows the first communication apparatus 102 to include additional fields in the CSI report configuration message, such as the type of codebooks and reporting granularity.

[0146] At sub-step 202A, the CSI report configuration message comprises an indicator for the performance codebook (CP k) for the UE 104fc (UEk), where the performance codebook (CP k) is for preferred precoder reporting. The sub-step 202A involving the inclusion of the indicator for the performance codebook (CP k) in the CSI report configuration message, serves to establish the framework for accurate and efficient preferred precoder reporting by the UE 104fc (UEk). By focusing on the preferred precoding directions, the first communication apparatus 102 can perform reliable and efficient data communication with the UE 104fc (UEfc).

[0147] At sub-step 202B, the CSI report configuration message further comprises an indicator for the interference codebook ( C / fc) for the UE 104fc (UEk), where the interference codebook (C / fc) is for interference direction reporting. The sub-step 202B is for enabling the UE 104fc (UEk) to provide the first communication apparatus 102 with information about channel directions that may create interference or that result in negligible interference. The interference codebook (C / fc) serves as a structured description of codewords that the UE 104fc (UEk) uses to report interference-related channel conditions, such as strong interfering directions that should be avoided or weak interfering directions that can be leveraged for efficient scheduling and resource allocation. Specifically, by incorporating interference-related CSI feedback from the UE 104fc (UEk), the first communication apparatus 102 can refine its scheduling and precoding strategies to minimize inter-user interference while maximizing data throughput for all UEs.

[0148] At step 204, the method 200 comprises transmitting a reference signal to the second communication apparatus 104 comprising the UE 104fc (UEk). The step 204 facilitating the accurate estimation of the downlink channel by the UE 104fc (UEk) by use of the reference signal. The reference signal, such as the Channel State Information Reference Signal (CSI-RS), serves as a pilot signal that carries predefined patterns known to both the first communication apparatus 102 and the UE 104fc (UEk). These patterns enable the UE 104fc (UEk) to measure the channel's characteristics, including amplitude, phase, and interference conditions, for subsequent reporting.

[0149] At step 206, the method 200 comprises receiving the Channel State Information, CSI, report from the second communication apparatus 104 comprising the UE 104fc (UEk). The step 206 is to provide the first communication apparatus 102 with the required data to perform efficient scheduling and precoding operations. By leveraging the CSI feedback, the first communication apparatus 102 can optimize the allocation of resources and design of precoding matrices to enhance spectral efficiency and minimize interference across multiple UEs in the network. The CSI report includes prominent information, such as the Precoding Matrix Indicator (PMI) and the Interference Matrix Indicator (IMI), which are derived by the UE 104fc (UEk) based on downlink channel estimations.At sub-step 206A, the CSI report comprises the Precoding Matrix Indicator, PMI (3P k), indicating a performance codeword selected from the performance codebook (CP k), by the UE 104k (UEk) as the UE 104k (UEk) preferred precoder from the performance codebook (CP k). The sub-step 206A is implemented after receiving the reference signal and the CSI report configuration message from the first communication apparatus 102, the UE 104fc (UEk) uses the specified performance codebook (CP k) to evaluate its channel conditions. By analyzing the strongest singular vectors from the channel matrix, the UE 104fc (UEk) selects a codeword from the performance codebook (CP k) as its preferred precoder. This selected codeword, represented by PMI JP k) is included in the CSI report sent to the first communication apparatus 102. Upon receiving the CSI report, the first communication apparatus 102 integrates the PMI JP k) into its precoding strategy, thereby aligning transmissions with the most favourable channel conditions for the UE 104fc (UEk). The PMI JP k) provides the first communication apparatus 102 with a clear indication of the UE 104fc (UEk) preferred transmission directions, ensuring effective resource allocation and enhanced network performance, particularly in multi-user MIMO scenarios.

[0150] At sub-step 206B, the CSI report further comprises an Interference Matrix Indicator, IMI iJ; k). indicating an interference codeword selected from the interference codebook (CI k), by the UE 104fc (UEk), the interference codeword indicating an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction. The sub-step 206B is to provide the first communication apparatus 102 with detailed information regarding potential interference scenarios affecting the UE 104fc (UEk). Implementation of this sub-step 206B involves the UE 104fc (UEk) to analyze the estimated downlink channel (Hk) conditions using the designated the interference codebook (CI k) as specified in the CSI report configuration message. Based on this analysis, the UE 104fc (UEk) selects an appropriate interference codeword from the interference codebook (CI k) that best represents its interference environment based on the interference condition or non-interference condition. If the interference direction meets the interference condition, the selected codeword indicates strong interference that other UEs should avoid. Conversely, if the interference direction meets the non-interference condition, the codeword indicates the weak interference direction that can be exploited for more efficient scheduling. The UE 104fc (UEk) then includes this IMI iJ; k) in its CSI report sent to the first communication apparatus 102. Upon receiving the CSI report, the first communication apparatus 102 utilizes the IMI iJ; k) to refine its precoding matrices and scheduling algorithms, ensuring optimized data transmission and reduced interference across the network.

[0151] In accordance with an embodiment, the method 200 further comprises performing scheduling and / or computing a precoder based on the Interference Matrix Indicator, IMI i J; k) and the Precoding Matrix Indicator, PMI JP k)- The PMI JP k) identifies the preferred precoding directions that maximize UEk's data transmission quality, while the IMI iJ; k) indicates interference directions that either meet interference conditions (strong interference to be avoided) or non-interference conditions (weak interference to be exploited).

[0152] In accordance with an embodiment, the method 200 further comprises receiving the Interference Matrix Indicator, IMI (J; k), by receiving a first Interference Matrix Indicator, IMI (Jn k), indicating the first interference direction being a direction that meets the interference condition, the first IMI thereby reporting a strong interference, and receiving a second Interference Matrix Indicator, IMI (J ntk), indicating a second interference direction being a direction that meets the non-interference condition, the second IMI thereby reporting a weak interference. By distinguishing between strong and weak interference directions, the first communication apparatus 102 can implement advanced scheduling and precoding strategies to maximize

[0153]

[0154] spectral efficiency and reduce inter-user interference, thereby improving overall network performance.

[0155] The steps 202 to 206 are only illustrative, and other alternatives can also be provided where one or more steps are added, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.There is provided a computer program product comprising instructions for performing the method 200 when executed by one or more processors (e.g., the processor 112) in a communication apparatus (e.g., the first communication apparatus 102). The computer program is implemented as an algorithm, embedded in a software stored in the non-transitory computer-readable storage medium having program instructions stored thereon, the program instructions being executable by the one or more processors in the computer system to execute the method 200. The non-transitory computer-readable storage means may include, but are not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. Examples of implementation of computer-readable storage medium, but are not limited to, an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Random Access Memory (RAM), a Read Only Memory (ROM), a Hard Disk Drive (HDD), a Flash memory, a Secure Digital (SD) card, a Solid-State Drive (SSD), a computer-readable storage medium, and / or a CPU cache memory.

[0156] FIG. 3 is a flowchart of a method for a second communication apparatus comprising a UE, in accordance with an embodiment of the present disclosure. FIG. 3 is described in conjunction with elements from FIGs. 1A, IB, 1C, and 2. With reference to FIG. 3, there is shown a method 300 for use in the second communication apparatus 104 comprising the UE 104k. The second communication apparatus 104 comprising the UE 104k is configured to execute the method 300. The method 300 includes steps from 302 to 308.

[0157] At step 302, the method 300 comprises receiving a CSI report configuration message. The CSI report configuration message comprises specific instructions and indicators, such as an indicator for a performance codebook and an indicator for an interference codebook for the UE 104fc, which can cause the UE 104fc (UEk) for selecting the appropriate precoding and interference directions.

[0158] At step 304, the method 300 further comprises receiving a reference signal. The reference signal is used for estimating the downlink channel characteristics. The reference signal, which can be a CSI-RS, serves as a predefined sequence that enables the UE 104fc (UEk) to measure various parameters of the downlink channel, such as signal strength, interference levels, and channel fading.

[0159] At step 306, the method 300 further comprises estimating a downlink channel (Hk) based on information received in the CSI report configuration message and the reference signal. The UE 104fc (UEk) is configured to estimate the downlink channel (Hk) matrix utilizing the received CSI report configuration message and the reference signal. The estimated downlink channel (Hk) matrix represents the channel's response and can be computed per frequency band or subband. The estimated downlink channel matrix is used for computing CSI feedback indicators, such as the PMI (0P k) and the IMI (0I k), which the UE 104fc (UEk) reports back to the first communication apparatus 102 for performing scheduling and precoding efficiently.

[0160] At step 308, the method 300 further comprises computing a PMI ( / / >. / <) and an IMI (J; k), where the PMI ( / / >. / <) indicates a performance codeword, selected from a performance codebook (CP k), identifying a preferred precoder of the UE 104fc, and the IMI (?;, / <) indicates an interference codeword, selected from an interference codebook (C; k), indicating an interference direction, where the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction, where the method 300 further comprises computing the PMI (?;> / <) and the IMI (?;, / <) based on the estimated downlink channel (Hk). The computation of both the PMI (0P k) and IMI (0I k) is based on the estimated downlink channel

[0161]

[0162] (Hk), which the UE 104fc (UEk) determines using the CSI report configuration message and the reference signal received fromthe first communication apparatus 102. By applying techniques, such as SVD to the estimated downlink channel (Hk) matrix, the UE 104k (UEk) extracts strong singular vectors for the PMI (P k) and weaker singular vectors for the IMI (I k). This structured approach ensures accurate and efficient CSI feedback, enabling the first communication apparatus 102 to perform optimal scheduling and precoding while mitigating interference.

[0163] The steps 302 to 308 are only illustrative, and other alternatives can also be provided where one or more steps are added, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

[0164] There is provided a computer program product comprising instructions for performing the method 300 when executed by one or more processors (e.g., the processor 118 of the UE 104k) in a communication apparatus (e.g., the communication apparatus 104). The computer program is implemented as an algorithm, embedded in a software stored in the non-transitory computer-readable storage medium having program instructions stored thereon, the program instructions being executable by the one or more processors in the computer system to execute the method 300. The non-transitory computer-readable storage means may include, but are not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. Examples of implementation of computer-readable storage medium, but are not limited to, an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Random Access Memory (RAM), a Read Only Memory (ROM), a Hard Disk Drive (HDD), a Flash memory, a Secure Digital (SD) card, a Solid-State Drive (SSD), a computer-readable storage medium, and / or a CPU cache memory.

[0165] FIG.4 is a flowchart that depicts Channel State Information (CSI) reporting in a wireless communication system, in accordance with an embodiment of the present disclosure. FIG. 4 is described in conjunction with elements from FIGs. 1A, 1B, 1C, 2, and 3. With reference to FIG. 4, there is shown a flowchart 400 that depicts CSI reporting in a wireless communication system. The flowchart 400 includes a series of operations from 402 to 410 during communication between the first communication apparatus 102 and the second communication apparatus 104 comprising the UE 104fc (UEk).

[0166] At operation 402, the first communication apparatus 102 is configured to transmit a CSI report configuration message to the second communication apparatus 104 comprising the UE 104k (UEk), where the UE 104k (UEk) is informed about the usage of two specific codebooks. The performance codebook (CP k), is designated for reporting the UE's preferred precoder, which ensures effective and reliable data communication. The interference codebook (CI k), is designated for reporting strong interference directions that may negatively impact data communication and to be avoided during data communication which further result in an enhanced data communication.

[0167] At operation 404, the first communication apparatus 102 is further configured to transmit a reference signal to the UE 104fc (UEk). The transmitted reference signal (i.e., the CSI RS) is used for downlink channel estimation at the UE 104fc (UEk)

[0168] At operation 406, the UE 104fc (UEk) is configured to compute a CSI report upon receiving the reference signal, and the CSI report configuration message from the first communication apparatus 102. The UE 104fc is configured to calculate key parameters, such as the PMI (P k) and the IMI (I k). The PMI (P k) indicates a codeword selected from the performance codebook (CP k), which reflects the UE’s preferred precoding configuration for data communication. The IMI (I k) represents a codeword selected from the interference codebook (C; k), which identifies strong interfering directions that could disrupt signal quality.At operation 408, the UE 104k (UEk) is configured to transmit the CSI report to the first communication apparatus 102. The CSI report includes the PMI (ℐP k) derived from (CP k), and the IMI (ℐI k) derived from (CI k).

[0169] At operation 410, the first communication apparatus 102 is configured to use the received CSI report for performing scheduling or computing a precoder, or a combination of both. This ensures that the first communication apparatus 102 may be configured to adapt the data transmission strategies effectively, considering both the UE's preferred precoding and the interference landscape, thereby improving the overall communication efficiency of MU-MIMO communication systems.

[0170] FIG. 5 is a flowchart that depicts Channel State Information (CSI) reporting in a wireless communication system, in accordance with another embodiment of the present disclosure. FIG. 5 is described in conjunction with elements from FIGs. 1A, 1B, 1C, 2, 3, and 4. With reference to FIG. 5, there is shown a flowchart 500 that depicts Channel State Information (CSI) reporting in a wireless communication system. The flowchart 500 includes a series of operations from 502 to 510 during the communication between the first communication apparatus 102 and the second communication apparatus 104 comprising the UE 104k (UEk).

[0171] At operation 502, the first communication apparatus 102 is configured to transmit a CSI report configuration message to the UE 104k (UEk), where the UE 104k (UEk) is informed about the usage of two specific codebooks. The performance codebook (CP k), is designated for reporting the UE's preferred precoder, which ensures effective and reliable data communication. The interference codebook (CI k), is designated for reporting weak interference directions which may be used during data communication with other UEs, which further results in an enhanced data communication.

[0172] At operation 504, the first communication apparatus 102 is further configured to transmit a reference signal to the UE 104k (UEk). The transmitted reference signal (i.e., the CSI RS) is used for downlink channel estimation at the UE 104fc (UEk)

[0173] At operation 506, the UE 104fc (UEk) is configured to compute a CSI report upon receiving the reference signal, and the CSI report configuration message from the first communication apparatus 102. The UE 104fc is configured to calculate key parameters, such as the PMI (P k) and the IMI (I k). The PMI (P k) indicates a codeword selected from the performance codebook (CP k), which reflects the UE’s preferred precoding configuration for enhancing communication performance. The IMI (I k) represents a codeword selected from the interference codebook (C; k), which identifies weak interfering directions.

[0174] At operation 508, the UE 104k (UEk) is configured to transmit the CSI report to the first communication apparatus 102. The CSI report includes the PMI (P k) derived from the performance codebook (CP k), and the IMI (I k) derived from the interference codebook (CI k).

[0175] At operation 510, the first communication apparatus 102 is configured to use the received CSI report for performing scheduling or computing a precoder, or a combination of both. This ensures that the first communication apparatus 102 may be configured to adapt the data transmission strategies effectively, considering both the UE's preferred precoding and the interference landscape, thereby improving overall communication efficiency of MU-MIMO communication systems.

[0176] FIG. 6 is a flowchart that depicts CSI reporting in a wireless communication system, in accordance with yet another embodiment of the present disclosure. FIG. 6 is described in conjunction with elements from FIGs. 1A, 1B, 1C, 2, 3, 4 and 5. With reference to FIG. 6, there is shown a flowchart 600 that depicts CSI reporting in a wireless communication system. The flowchart 600 includes a series of operations from 602 to 610 during the communication between the first communication apparatus 102 and the second communication apparatus 104 comprising the UE 104k (UEk).At operation 602, the first communication apparatus 102 is configured to transmit a CSI report configuration message to the UE 104k (UEk), where the UE 104k (UEk) is informed about the usage of three specific codebooks that is the performance codebook (CP k) for preferred precoder reporting, a first interference codebook (Cn k) for strong interfering directions reporting and a second interference codebook (C,2 ik) for weak interfering directions reporting.

[0177] At operation 604, the first communication apparatus 102 is further configured to transmit a reference signal to the UE 104k (UEk). The transmitted reference signal (i.e., the CSI RS) is used for downlink channel estimation at the UE 104k (UEk)

[0178] At operation 606, the UE 104k (UEk) is configured to compute a CSI report upon receiving the reference signal, and the CSI report configuration message from the first communication apparatus 102. The UE 104k is configured to calculate key parameters, such as the PMI (JP k) and the IMI

[0179]

[0180] and the IMI (J / 2,fc)- The PMI (JP k) indicates a codeword selected from the performance codebook (CP k), which reflects the UE’s preferred precoding configuration for enhancing communication performance. The IMI

[0181]

[0182] represents a codeword selected from the interference codebook (CI1,k), which the UE 104k identifies as representatives of strong interfering directions. The IMI (ℐI2,k) represents a codeword selected from the interference codebook (CI2,k), which the UE 104k identifies as representatives of weak interfering directions.

[0183] At operation 608, the UE 104k (UEk) is configured to transmit the CSI report to the first communication apparatus 102. The CSI report includes the PMI (JP k) derived from the performance codebook (CP k), the IMI

[0184]

[0185] derived from the interference codebook CIl k') and the IMI (J;2 k) derived from the interference codebook (C;2 k).

[0186] At operation 610, the first communication apparatus 102 is configured to use the received CSI report for performing scheduling or computing a precoder, or a combination of both. This ensures that the first communication apparatus 102 may be configured to adapt the data transmission strategies effectively, considering both the UE's preferred precoding and the interference landscape, thereby improving the overall communication efficiency of MU-MIMO communication systems.

[0187] The present disclosure introduces an efficient and adaptive approach to channel state information (CSI) reporting in multi-user (MU) MEMO systems. The present disclosure leverages dual codebooks (i.e., the performance codebook (CP k), and the interference codebook (CI,k)l to separately optimize preferred precoding and interference direction reporting. This adaptability enables the dynamic selection of interference codebooks for either strong or weak interference scenarios, ensuring precise representation of channel conditions. By refining Precoding Matrix Indicators (PMIs) and Interference Matrix Indicators (IMIs) independently, the disclosed method enhances spectral efficiency, minimizes inter-user interference, and improves overall system throughput. Additionally, the process seamlessly integrates feedback into scheduling and precoding decisions, ensuring real-time responsiveness and resource optimization.

[0188] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, forbrevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.

Claims

CLAIMS1. A first communication apparatus (102) configured totransmit a Channel State Information, CSI, report configuration message to a second communication apparatus (104) comprising a User Equipment, UE (104k), UEk, the CSI report configuration message comprising:an indicator for a performance codebook, CP k, for the UE (104k), UEk, andan indicator for an interference codebook CI k, for the UE (104k), UEk, whereinthe performance codebook, CP k, is for preferred precoder reporting andthe interference codebook, CI k, is for interference direction reporting,transmit a reference signal to the second communication apparatus (104) comprising the UE (104k), UEk; receive a CSI report from the second communication apparatus (104) comprising the UE (104k), UEk, the CSI report comprising:a Precoding Matrix Indicator, PMI JP k, indicating a performance codeword selected from the performance codebook CP k, by the UE (104fc), UEk, as the UE’s, UEk, preferred precoder from the performance codebook, CP kand an Interference Matrix Indicator, IMI JI k, indicating an interference codeword selected from the interference codebook CI k, by the UE (104fc), UEk, the interference codeword indicating an interference direction, wherein the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction.

2. The first communication apparatus (102) according to claim 1, wherein the first communication apparatus (102) is further configured to perform scheduling and / or computing a precoder based on the Interference Matrix Indicator, IMI ℐI k, and the Precoding Matrix Indicator, PMI ℐP k.

3. The first communication apparatus (102) according to claim 1 or 2, wherein the first communication apparatus (102) is further configured to receive the Interference Matrix Indicator, IMI ℐI k, byreceiving a first Interference Matrix Indicator, IMIk, indicating a first interference direction being a direction that meets the interference condition; the first IMI thereby reporting a strong interference direction, andreceiving a second Interference Matrix Indicator, IMI J ‘I2 k, indicating a second interference direction being a direction that meets the non-interference condition; the second IMI thereby reporting a weak interference direction.

4. The first communication apparatus (102) according to claim 1, 2 or 3, wherein the CSI report configuration message includes an indicator for a strong interference codebook CIl kand an indicator for a weak interference codebook CI2 k.

5. The first communication apparatus (102) according to claim 1, 2 or 3, wherein the strong interference codebook CIl kis a Type II codebook and the weak interference codebook CI2 kis a Type I codebook.

6. The first communication apparatus (102) according to any preceding claim, wherein the CSI report configuration message includes an interference condition and / or a non-interference condition.

7. The first communication apparatus (102) according to any preceding claim, wherein the CSI report includes one PMI, JP k, and one IMI, JI k, per (sub)band utilized.

8. The first communication apparatus (102) according to any preceding claim, wherein the performance codebook CP k, has an accuracy that is higher than an accuracy of the interference codebook CI k.

9. The first communication apparatus (102) according to any preceding claim, wherein the performance codebook CP k, is a Type II codebook10. The first communication apparatus (102) according to any preceding claim, wherein the interference codebook CI k, is a Type I codebook.

11. The first communication apparatus (102) according to any preceding claim, wherein the interference codebook CI k, is a Type II codebook when reporting strong interference, and a Type I codebook when reporting weak interference.

12. The first communication apparatus (102) according to any preceding claim, wherein reporting the Precoding Matrix Indicator, PMI JP k, requires bP kbits and reporting the Interference Matrix Indicator, IMI JI k, requires bt kbits, where bt k< bp,k-13 The first communication apparatus (102) according to any preceding claim, wherein the first communication apparatus (102) is further configured to perform precoding for a (sub)band, the precoding comprisingavoiding the interfering directions indicated by the IMIs JI ltJI2,...,3iik,...,3 / IKreported by one or more second communication apparatuses comprising the UEs 1,2,...,fc,when the IMIs 7; l, JI 2,..., J‘I k,...,indicate interference directions that meet the interference condition of the respective UEs 1,2,..., fc,14. The communication apparatus (102) according to any preceding claim, wherein the first communication apparatus (102) is further configured to perform scheduling for a (sub)band byhaving received the PMI JP kand IMI JI kfrom the UE (104k), UEk. andreceiving a PMI JP k, from another UE (UEk,),comparing the received codewords andif the PMI of UEk', is equivalent to the IMI for the UE (104k), UEk, when the interference direction reported by the UE (104k), UEk, is a direction that meets the non-interference condition of the UE (104k), UEk, then the two UEs can be paired in the (sub)band.

15. The first communication apparatus (102) according to any preceding claim, wherein the reference signal comprises at least one pilot, such as a Channel State Information Reference Signal, CSI-RS.

16. The first communication apparatus (102) according to any preceding claim, wherein the first communication apparatus (102) is a Base station.

17. A method (200) for a first communication apparatus (102), the method (200) comprising:transmitting a Channel State Information, CSI, report configuration message to a second communication apparatus (104) comprising a User Equipment, UE (104k), UEk, the CSI report configuration message comprising:an indicator for a performance codebook, CP kfor the UE (104k), UEkandan indicator for an interference codebook, CI kfor the UE (104k), UEk, whereinthe performance codebook, CP kis for preferred precoder reporting andthe interference codebook, CI kis for interference direction reporting,transmitting a reference signal to the second communication apparatus (104) comprising UE (104k), UEk.receiving a CSI report from the second communication apparatus (104) comprising the UE (104k), UEk. the CSI report comprisinga Precoding Matrix Indicator, PMI, JP k, indicating a performance codeword selected from the performance codebook, CP k, by the UE (104k), UEkas the UE’s, UEk, preferred precoder from the performance codebook, CP kand an Interference Matrix Indicator, IMI, JI k, indicating an interference codeword selected from the interference codebook, CI k, by the UE (104k), UEk, the interference codeword indicating an interference direction, wherein the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction.

18. The method (200) according to claim 17, wherein the method (200) further comprisesperforming scheduling and / or computing a precoder based on the Interference Matrix Indicator, IMI, ℐI kand the Precoding Matrix Indicator, PMI, ℐP k.

19. The method (200) according to claim 17, wherein the method (200) further comprises receiving the Interference Matrix Indicator, IMI, ℐI k, byreceiving a first Interference Matrix Indicator, IMI,k, indicating a first interference direction being a direction that meets the interference condition; the first IMI thereby reporting a strong interference direction, andreceiving a second Interference Matrix Indicator, IMI, ℐI2 k, indicating a second interference direction being a direction that meets the non-interference condition; the second IMI thereby reporting a weak interference direction.

20. A computer program product comprising program instructions for performing the method (200) according to claim 17 or 18, when executed by one or more processors in a first communication apparatus (102).

21. A second communication apparatus (104) comprising a User Equipment, UE (104k), UEk, configured toreceive a CSI report configuration message,receive a reference signal,estimate a downlink channel, Hkbased on information received in the CSI report configuration message and the reference signal then,compute a PMI, ℐP kand an IMI, ℐI k, wherein the PMI, ℐP kindicates a performance codeword, selected from a performance codebook, CP k, identifying a preferred precoder of the UE(104k), and the IMI ℐI kindicates an interference codeword, selected from an interference codebook, CI k, indicating an interference direction, wherein the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction, wherein the second communication apparatus (104) comprising the UE (104k), is further configured to compute the PMI, ℐP kand the IMI, ℐI kbased on the estimated downlink channel, Hk.

22. A method (300) for a second communication apparatus (104) comprising a User Equipment, UE (104k), UEk, the method (300) comprisingreceiving a CSI report configuration message,receiving a reference Signal,estimating a downlink channel, Hkbased on information received in the CSI report configuration message and the reference signal thencomputing a PMI, ℐP kand an IMI, ℐI k, wherein the PMI, ℐP kindicates a performance codeword, selected from a performance codebook, CP k, identifying a preferred precoder of the UE(104k), and the IMI ℐI kindicates an interference codeword, selected from an interference codebook CI k, indicating an interference direction, wherein the interference direction is a direction that meets an interference condition thereby reporting a strong interference in that direction or a direction that meets a non-interference condition thereby reporting a weak interference in that direction, wherein the method (300) further comprises computing the PMI, ℐP kand the IMI, ℐI kbased on the estimated downlink channel, Hk.

23. A computer program product comprising program instructions for performing the method (300) according to claim 22, when executed by one or more processors in a second communication apparatus (104).

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