CN110999366B - System and method for determining Channel Quality Indicator (CQI) index values - Google Patents

Abstract

A system and method for determining a Channel Quality Indicator (CQI) index value is disclosed. In one embodiment, a communication method performed by a first communication node comprises: notifying a second communication node of at least one set of Channel Quality Indicator (CQI) calculation parameters, wherein the at least one set of CQI calculation parameters is determined from a plurality of sets of CQI calculation parameters, each set of CQI calculation parameters including at least one predefined CQI calculation parameter; and receiving a CQI index value from the second communication node.

Description

System and method for determining Channel Quality Indicator (CQI) index values

Technical Field

The present disclosure relates generally to wireless communications and, more particularly, to systems and methods for determining a Channel Quality Indicator (CQI) index value for wireless communications.

Background

Wireless network systems have become a prevalent means by which a majority of people worldwide have come to communicate. Wireless communication devices have become smaller and more powerful in order to meet consumer needs and to improve portability and convenience. Consumers have found many uses for wireless communication devices, such as cellular telephones, personal digital assistants, and the like, which require reliable service and extended coverage areas.

A typical wireless communication network (e.g., employing frequency, time, and/or code division techniques) includes one or more base stations (often referred to as "BSs"), each providing geographic radio coverage, and one or more wireless user equipment (often referred to as "UEs") that can transmit and receive data within the radio coverage. Such communication between the BS and the UE may be degraded due to channel variations and/or interference and power variations. In this regard, the UE may measure the respective reference signals using a predefined protocol and/or following higher layer instructions in order to estimate channel conditions, which are typically expressed as "Channel State Information (CSI)" fed back to the BS. From the CSI reports from the UE, the BS can better understand the channel and UE capabilities.

Typically, various indicators are included in the CSI, such as, for example, Rank Indicator (RI), Precoding Matrix Indicator (PMI), and Channel Quality Indicator (CQI), which is typically used to assess channel quality. The CSI is typically estimated as an index when the channel quality satisfies one or more criteria, each of which is associated or related to a Modulation and Coding Scheme (MCS) and a code rate.

In a Long Term Evolution (LTE) network, a UE determines CSI reference resources that include information on how resource elements used to transmit downlink data are respectively distributed in one or more resource blocks. And according to measurements on a channel state information reference signal (CSI-RS) and a cell specific reference signal (CRS) transmitted from the BS, the UE determines an index of CQI (hereinafter referred to as "CQI index") based on the CSI reference resource and sends a CQI report back to the BS. There are two types of CQI reports: periodic and aperiodic. Periodic CQI reports are typically carried by the Physical Uplink Control Channel (PUCCH), but if the UE needs to send UL data in the same subframe as the scheduled periodic CQI report, the periodic CQI report will be carried along with the UL data in the Physical Uplink Shared Channel (PUSCH). This is because the UE cannot transmit on PUCCH and PUSCH simultaneously. In this case, the periodic PUCCH resource will be idle. Since periodic CQI reporting always has a "feedback overhead", the reporting granularity is relatively coarse. To receive more detailed CQI reports, the BS (e.g., eNB) may trigger aperiodic CQI reports when needed. Aperiodic CQI reports are transmitted on PUSCH along with UL data or separately.

The granularity of CQI reporting may be divided into three levels: broadband, UE-selected sub-band, and higher configured sub-band. The wideband report provides one CQI index value for the entire downlink system bandwidth. The UE-selected subband CQI reporting partitions the system bandwidth into multiple subbands, selects a preferred subband set (e.g., the best M subbands), and then reports one CQI index value for the wideband and one differential CQI index value for the preferred subband set (assuming transmission on only the selected M subbands). Higher layer configured subband reporting provides the highest granularity because it partitions the overall system bandwidth into multiple subbands and then reports one wideband CQI index value and multiple differential CQI index values, one for each subband.

In an LTE network, a UE receives a CSI measurement request, and then determines a subframe for measuring CSI according to a predefined time offset relationship and a condition for determining whether the subframe is a valid subframe. In the measurements performed to obtain CSI, measurements of CQI are performed, as discussed further below. The CQI index and its interpretation (i.e. the CQI index corresponds to the MCS level consisting of a set of parameters including modulation, code rate and efficiency) is given in several predefined CQI tables for reporting CQI. The UE should derive each CQI value reported in the uplink subframe in the highest CQI index in the CQI table that satisfies the predetermined condition.

For example, a single PDSCH Transport Block (TB) having a combination of a modulation scheme and a transport block size corresponding to a CQI index and occupying a set of downlink physical Resource Blocks (RBs) called CSI reference resources may be received with a transport block error probability (BLER) of not more than 0.1 (i.e., a target BLER). The UE should derive channel measurements for calculating CQI based on CRS and/or CSI-RS. Typically, the UE derives the SINR of the channel based on the CRS/CSI-RS and calculates the respective BLER for each MCS level based on the SINR to see if the BLER is < 0.1. To calculate BLER, the PDSCH Transport Block Size (TBS) is first determined. The TBS is determined by the number of REs (resource elements) that can be used to transmit data and the corresponding MCS level. Furthermore, the number of REs available for transmitting data is defined by the "CSI reference resource", which depends on the set of downlink physical resource blocks involved in the CQI derivation and some assumptions about the CSI reference resource, as discussed further below.

In LTE networks, the UE uses a series of assumptions to determine CSI reference resources. Some of the assumptions are: (1) the first 3 OFDM symbols are occupied by PDCCH signals; (2) assuming CSI-RS and zero-power CSI-RS overhead for different Transmission Mode (TM)/configurations; (3) assuming DMRS overhead for different Transmission Modes (TM)/configurations; and (4) assuming CRS overhead for different Transmission Mode (TM)/configurations.

The conventional procedure for calculating the CQI index can be summarized as follows:

step 1: the UE measures the CRS and/or CSI-RS to obtain SINR.

Step 2: the UE determines a CSI reference resource. The CSI reference resource is determined based on the TM, the RI value, the number of antenna ports, the CSI reporting configuration, and assumptions of the CSI reference resource in the LTE standard.

Step 3: the UE derives a CQI index. Each MCS level corresponds to one TBS based on the efficiency of the MCS level and the CSI reference resource determined in step 2. The UE determines the BLER of the TBS corresponding to each MCS level. The final CQI index value for reporting corresponds to the highest MCS level that satisfies the corresponding BLER < 0.1. If CQI index 1 does not satisfy the condition, the final CQI index value for reporting is 0.

Step 4: as described above, the UE learns the subframe index of the uplink subframe using a predefined time offset, and reports the CQI index calculated in step 3 using the uplink subframe.

Step 5: the BS uses the CQI index to determine how to allocate resources and which MCS to use for subsequent downlink transmissions.

In the conventional technique as described above, in order to calculate the CQI index, the UE must: (1) determining a CSI reference resource; and (2) know what the target BLER is. In LTE, the target BLER is fixed to 0.1, and the assumption that the CSI reference resource is determined is also fixed in the protocol, as described above. Therefore, the UE only needs to know the set of downlink Resource Blocks (RBs) to determine the CSI reference resource to calculate the CQI index.

However, in New Radio (NR) networks, such as fifth generation (5G) networks, the use of the above-mentioned conventional assumptions, which cannot be dynamically or semi-persistently configured (i.e., fixed), may lead to various problems such as, for example, inaccurate and unreliable estimation of CQI index values due to various application requirements (e.g., ultra-reliable low-latency communication (URLLC), large-scale machine type communication (mtc) networks, etc.) and different protocols (e.g., scalable Transmission Time Interval (TTI) length, variable number of symbols used by PDCCH, etc.). Therefore, existing systems and methods for estimating CQI index values are not entirely satisfactory.

Disclosure of Invention

The exemplary embodiments disclosed herein are directed to solving the problems associated with one or more of the problems set forth in the prior art, and providing additional features that will become apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. In accordance with various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. It is to be understood, however, that these embodiments are presented by way of example, and not limitation, and that various modifications to the disclosed embodiments may be apparent to those of ordinary skill in the art upon reading this disclosure, while remaining within the scope of the present invention. According to an exemplary embodiment of the present invention, one or more "CQI calculation parameters" for determining CSI reference resources may be dynamically assigned to a UE by a BS, which is then used to determine a CQI index value.

In one embodiment, a communication method performed by a first communication node comprises: notifying a second communication node of at least one set of Channel Quality Indicator (CQI) calculation parameters, wherein the at least one set of CQI calculation parameters is determined from a plurality of sets of CQI calculation parameters, each set of CQI calculation parameters including at least one predefined CQI calculation parameter; receiving a CQI index value from the second communication node.

In another embodiment, a method performed by a second communication node comprises: receiving, from a first communication node, an identification of at least one set of Channel Quality Indicator (CQI) estimation parameters for determining a CQI index value, wherein the at least one set of CQI calculation parameters is determined from a plurality of sets of CQI calculation parameters, each set of CQI calculation parameters comprising at least one predefined CQI calculation parameter; determining a CQI index value based on the at least one set of CQI calculation parameters; and transmitting a CQI report to the first communication node.

Drawings

Various exemplary embodiments of the present invention are described in detail below with reference to the following drawings. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention to facilitate the reader's understanding of the invention. Accordingly, the drawings are not to be considered limiting of the breadth, scope, or applicability of the present invention. It should be noted that for clarity and ease of illustration, the drawings are not necessarily drawn to scale.

Fig. 1 illustrates an exemplary cellular communication network in which techniques disclosed herein may be implemented, according to some embodiments of the invention.

Fig. 2 illustrates a block diagram of an exemplary base station and user equipment, in accordance with some embodiments of the present invention.

Fig. 3 illustrates a flow diagram of an exemplary process for deriving a CQI index value, according to some embodiments of the invention.

Detailed Description

Various exemplary embodiments of the invention are described below with reference to the drawings to enable one of ordinary skill in the art to make and use the invention. It will be apparent to those of ordinary skill in the art that, upon reading this disclosure, various changes or modifications may be made to the examples described herein without departing from the scope of the invention. Accordingly, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the particular order or hierarchy of steps in the methods disclosed herein is merely exemplary. Based upon design preferences, the specific order or hierarchy of steps in the methods or processes disclosed may be rearranged while remaining within the scope of the present invention. Accordingly, one of ordinary skill in the art will understand that the methods and techniques disclosed herein present the various steps or actions in a sample order, and the invention is not limited to the specific order or hierarchy presented unless otherwise explicitly claimed.

Fig. 1 illustrates an example wireless communication network 100 in which techniques disclosed herein may be implemented, in accordance with various embodiments of the present disclosure. Exemplary wireless communication network 100 includes a Base Station (BS)102 and a User Equipment (UE)104 that can communicate with each other via a communication link 110 (e.g., a wireless communication channel), and a cluster of conceptual cells 126, 130, 132, 134, 136, 138, and 140 that cover a geographic area 101. In fig. 1, the BS 102 and the UE 104 are contained within the geographic boundaries of the conceptual cell 126. Each of the other concept cells 130, 132, 134, 136, 138 and 140 may include at least one base station operating at its allocated bandwidth to provide sufficient radio coverage to its intended users. For example, the base station 102 may operate at the allocated channel transmission bandwidth to provide sufficient coverage to the UE 104. Base station 102 and UE 104 may communicate via downlink radio frames 118 and uplink radio frames 124, respectively. Each downlink radio frame 118/uplink radio frame 124 may also be divided into subframes 120/150, subframe 120/150 may include data symbols 122/128. In the present disclosure, a Base Station (BS)102 and a User Equipment (UE)104 are described herein as non-limiting examples of "communication devices" that can generally practice the methods disclosed herein. Such communication devices may be capable of wireless and/or wired communication in accordance with various embodiments of the present invention.

Fig. 2 illustrates a block diagram of an exemplary wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM/OFDMA signals) in accordance with some embodiments of the present invention. The wireless communication system 200 may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one exemplary embodiment, the wireless communication system 200 can be utilized for transmitting and receiving data symbols in a wireless communication environment, such as the wireless communication network 100 of fig. 1, as described above.

The wireless communication system 200 generally includes a base station 202 and a UE 204. Base station 202 includes a BS transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each coupled and interconnected with each other as needed via a data communication bus 220. The UE 204 includes a UE transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each coupled and interconnected with each other as needed via a data communication bus 240. Base station 202 communicates with UE 204 via a communication channel 250, which communication channel 250 may be any wireless channel or other medium known in the art suitable for data transmission as described herein.

As will be appreciated by one of ordinary skill in the art, the wireless communication system 200 may also include any number of modules in addition to those shown in fig. 2. Those of skill in the art will appreciate that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented as hardware, computer readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Such functionality may be implemented as hardware, firmware, or software, depending upon the particular application and design constraints imposed on the overall system. Skilled artisans familiar with the concepts described herein may implement this functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present disclosure.

According to some embodiments, UE transceiver module 230 may be referred to herein as an "uplink" transceiver, which includes RF transmitter and receiver circuitry that are each coupled to a UE antenna 232. A duplex switch (not shown) may alternately couple the uplink transmitter or receiver to the uplink antenna in a time-duplex manner. Similarly, BS transceiver module 210 may be referred to herein as a "downlink" transceiver, which includes RF transmitter and receiver circuits that are each coupled to BS antenna 212, according to some embodiments. A downlink duplex switch (not shown) may alternately couple a downlink transmitter or receiver to the BS antenna 212 in a time-duplex manner. Two transceivers: the operation of BS transceiver module 210 and UE transceiver module 230 are coordinated in time such that an uplink receiver is coupled to UE antenna 232 for receiving transmissions on communication channel 250 while a downlink transmitter is coupled to BS antenna 212. Preferably there is a tight time synchronization with only a minimum guard time between changes in the duplex direction.

UE transceiver module 230 and BS transceiver module 210 are configured to communicate via communication channel 250 and cooperate with appropriately configured RF antenna arrangements BS antenna 212/UE antenna 232 that may support particular wireless communication protocols and modulation schemes. In some demonstrative embodiments, UE transceiver module 230 and BS transceiver module 210 are configured to support industry standards, such as Long Term Evolution (LTE) and emerging 5G standards. It should be understood, however, that the present invention is not necessarily limited to application to a particular standard and associated protocol. Rather, UE transceiver module 230 and BS transceiver module 210 may be configured to support alternative or additional wireless data communication protocols, including future standards or variants thereof.

According to various embodiments, base station 202 may be, for example, an evolved node B (eNB), a serving eNB, a target eNB, a femto station, or a pico station. In some embodiments, the UE 204 may be embodied in various types of user equipment, such as a mobile phone, a smartphone, a Personal Digital Assistant (PDA), a tablet computer, a laptop computer, a wearable computing device, and so forth. The BS processor module 214 and the UE processor module 236 may be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. In this manner, a processor may be implemented as a microprocessor, controller, microcontroller, state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by the BS processor module 214 and the UE processor module 236, or in any practical combination thereof. The BS memory module 216 and the UE memory module 234 may be implemented as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, the BS memory module 216 and the UE memory module 234 may be coupled to the BS processor module 214 and the UE processor module 236, respectively, such that the BS processor module 214 and the UE processor module 236 may read information from and write information to the BS memory module 216 and the UE memory module 234, respectively. The BS memory module 216 and the UE memory module 234 may also be integrated into their respective BS processor module 214 and UE processor module 236. In some embodiments, the BS memory module 216 and the UE memory module 234 may each include cache memory for storing temporary variables or other intermediate information during execution of instructions for execution by the BS processor module 214 and the UE processor module 236, respectively. The BS memory module 216 and the UE memory module 234 may also each include non-volatile memory for storing instructions for execution by the BS processor module 214 and the UE processor module 236, respectively.

Network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of base station 202 that enable bi-directional communication between BS transceiver module 210 and other network components and communication devices configured to communicate with base station 202. For example, the network communication module 218 may be configured to support internet or WiMAX services. In a typical deployment, but not limited to, the network communication module 218 provides an 802.3 ethernet interface so that the BS transceiver module 210 can communicate with a conventional ethernet-based computer network. In this manner, the network communication module 218 may include a physical interface for connecting to a computer network (e.g., a Mobile Switching Center (MSC)). As used herein with respect to a specified operation or function, the terms "configured to," "configured to," and variations thereof refer to a device, component, circuit, structure, machine, signal, etc., that is physically constructed, programmed, formatted, and/or arranged to perform the specified operation or function.

Referring again to fig. 1, as described above, when the BS 102 is ready to transmit and receive data from the UE 104, the channel estimation procedure is typically performed before the BS actually transmits and receives data from the UE 104. During such a channel estimation process, one or more reference signals (e.g., CSI-RS and/or CRS) are typically transmitted from BS 102 to UE 104 via one or more physical channels. Based on the measurements on the reference signal, the UE 104 determines the CQI index and sends a CQI report containing the CQI index back to the BS 102.

According to various embodiments, a method of deriving a CQI index using various sets of "CQI calculation parameters" is disclosed. Unlike LTE networks that rely on a fixed set of assumptions (i.e., the 7 assumptions discussed above), in some embodiments, such various sets of CQI computation parameters may provide respective different sets of assumptions to allow the BS to determine respective CSI reference resources for different scenarios/applications that will occur in NR networks. More specifically, in some embodiments, based on one of various scenarios/applications, the BS may inform the UE of a set of CQI calculation parameters, and the UE may determine corresponding CSI reference resources based on the CQI calculation parameters contained in the set to derive CQI indices, so that the BS may interpret the CQI indices more accurately using the information it transmits to the UE.

According to some embodiments, a table is provided that includes a plurality of CQI indices, each CQI index being associated with a respective one of a plurality of CQI calculation parameters, as shown in table 2 below. As shown in table 2, the first column represents a CQI index; the second column represents the number of symbols (e.g., OFDM symbols) per downlink slot; the third column indicates each occupied by a control channelA number of first symbols (e.g., OFDM symbols) in a number of resource blocks; the fourth column indicates the rate matching parameters; and the fifth column represents a target block error rate (BLER). It should be understood that the present invention is not limited to the exemplary estimated parameters shown in table 2 below. In other embodiments, other CQI calculation parameters (e.g., number of resource blocks, data resource mapping parameters, number of downlink symbols per slot, and control channel resource parameters) may be added as columns in the following table, or in place of one or more columns 2-5 in the following table. Further, it should be understood that the values contained in table 2 below are merely exemplary, and that other values may be utilized in NR systems according to various embodiments of the present invention, for example, to provide various joint encoding techniques. For another example, including time domain (e.g., number of symbols) and frequency domain (e.g., groups of RBs or of REs)Group of) May replace column 3 of table 2 below.

TABLE 2

In some embodiments, BS 102 informs UE 104 of one set of CQI calculation parameters through various methods. For example, the BS 102 may inform the UE 104 of the CQI calculation parameter index value as shown in table 2 above through signaling (e.g., a Radio Resource Control (RRC) instruction having 4 bits, a Medium Access Control (MAC) signal, etc.). Accordingly, the UE 104 may obtain a corresponding CQI calculation parameter from a CQI calculation parameter (CQIDP) index value. In another example, table 2 above is grouped into multiple groups, e.g., a first group having sets corresponding to CQIDP indices from 0 to 7, and a second group having sets corresponding to CQIDP indices from 8 to 14. The BS 102 first informs the UE 104 of which group it is through first signaling (e.g., RRC/MAC signal with 1 bit) with fewer bits, and then within the group, the BS informs which set it is through second signaling (e.g., Downlink Control Information (DCI) signal with 3 bits). However, as described above, the values in table 2 are merely exemplary, and various values and parameters may be used in place of the values and parameters in table 2 according to various system requirements and/or applications, according to various embodiments.

Second, the BS 102 informs the UE 104 which CSI reference resource the UE 104 may use to estimate the CSI index. In some embodiments, the BS 102 informs the UE 104 where the resources are located along the time domain, e.g., in which downlink slot/mini-slot the CSI reference resource is located. In some embodiments, a time offset relationship (n-n) between downlink time slots/minislots and uplink time slots/minislots is provided_{CQI_ref}) Wherein "n" denotes an index of uplink slot/mini slot, and "n_{CQI_ref}"denotes a time offset. In some embodiments, the relationship is determined by the BS and communicated to the UE. Specifically, the BS may determine the relationship by configuring a time offset and signaling it to the UE (e.g., RRC/MAC/DCI signal). Further, the time offset may be determined by the BS from a predefined set of time offset values (e.g., 2, 3, 4, and 5) and thereafter transmitted to the UE. There are various factors that may affect this determination. For example, in a URLLC scenario, the BS may need a shorter offset (e.g., 2) so that the CQI report is more reliable (since it represents the quality of the channel only 2ms before). In other embodiments, the relationship is predefined. For example, n-n_{CQI_ref}Is a particular slot/mini-slot of the various slots/mini-slots.

In some embodiments, the two or more parameter sets shown in the above exemplary table 2 may be configured by the BS through higher layer signaling, and at least one set may be triggered by a DCI signal. The UE determines a corresponding CQI index using the at least one set and reports the corresponding CQI index to the BS. In some embodiments, since two CQI indices mean BLER of two CSI reference resources, the BS may consider the two CQI indices and obtain more information, e.g., channel state information and UE capability. In some embodiments, to reduce resource usage for the instructions, a portion of the CQI calculation parameters may be preconfigured without signaling from the BS to the UE. Further, such pre-configuration may be a specific value of the CQI calculation parameter, or may be a mapping rule/relationship between the CQI calculation parameter and other configurations/conditions. For example, the BS and the UE may first agree on the number of OFDM symbols occupied by the PDCCH (e.g., 2), agree on a mapping rule between DMRS REs and the RI value most recently used by the UE, and agree on a mapping rule between target BLER and slot length. For example, the BS and UE may be pre-configured (i.e., agreed): under a certain subcarrier spacing (e.g., 15kHz) configuration, the target BLER is 0.01 when the length of the slot is <7, and 0.1 when the length of the slot is > 7. Therefore, the BS only needs to configure the number of OFDM symbols (i.e., the second column in table 1) for the UE to derive the CQI index value.

In NR, the scheduling units in the time domain are time slots or minislots, and thus the CSI reference resource definition in the time domain should also be based on time slots or minislots. In NR, one slot/mini slot contains a predetermined number of OFDM symbols, e.g., from 1 to 14, compared to the LTE system, where one slot contains, e.g., 7 symbols (normal CP). According to a first method for NR communication, a BS may set a threshold (e.g., K0-7) in an available number of OFDM symbols (e.g., 1-14) in each slot. When the UE measures that the number of its respective CSI reference resources is greater than K0, the UE estimates a CQI index using K1 OFDM symbols; and when the UE measures that the number of its respective CSI reference resources is less than K0, the UE estimates the CQI index using K2 OFDM symbols, where K0, K1, and K2 are integer values. The UE may determine K0, K1, and K2 according to a predetermined protocol established with the BS or an indication signal from the BS. For example, if K0 belongs to {4, 7}, a specific value of K0 is configured by the BS through one 1-bit signaling, and the UE may determine K1 according to a predetermined relationship or algorithm (e.g., K0 — K1) and may determine K2, e.g., where K2 is equal to the actual number of OFDM symbols of the CSI reference resource.

According to a second approach, the BS may divide all available number (theoretically 1-14) OFDM symbols in each slot into subsets, where each subset has M OFDM symbols, and the last (remaining) subset may have less than M number of OFDM symbols. When the number of OFDM symbols for which the UE measures its respective CSI reference resource is equal to one of the number of OFDM symbols in the subset, the UE estimates the CQI index using the average (and rounding if necessary) of the number of OFDM symbols within the subset. For example, when M ═ 5, the plurality of OFDM symbols may be divided into subsets: {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, and {11, 12, 13, 14, 15}, having mean values of 3, 8, and 13, respectively. And when the number of OFDM symbols of the CSI reference resource is 4 (falls in the first subset), the UE then estimates the CQI index using the average 3 of the first subset. In some embodiments, the UE may determine M based on a predetermined arrangement or agreement with the BS, or alternatively, based on an indication signal from the BS.

According to a third approach, the BS may determine the number of OFDM symbols used for CQI derivation from a predefined set of values (e.g., {4, 7, 10, 14}) and communicate it to the UE (e.g., through 2-bit signaling). This method is a special case of the above embodiment, where only the first two columns remain in table 2.

According to some embodiments, one or more of the CQI calculation parameters may be preconfigured as fixed values. For example, the estimation parameter of "number of symbols" as shown in the second column of table 2 above may be preconfigured to be 2. In some embodiments, the BS and the UE may also pre-establish a method for determining the parameters. For example, the UE may determine the CQI estimation parameters from actual parameters of the CSI reference resources.

In some embodiments, the above CSI reference resources that the UE can use to estimate the CQI index are also limited by the CQI calculation parameters. In other words, in such embodiments, the CSI reference resource needs to satisfy each CQI calculation parameter contained in the informed assumption, and if the UE cannot find, for example, a slot/mini-slot that satisfies all CQI calculation parameters in a defined parameter set corresponding to a corresponding CQI index value, the UE will not report the CQI index value to the BS.

In an LTE network, when data (e.g., downlink data) is transmitted, symbols of a Transport Block (TB) are used. Generally, data for selecting MCS (modulation and coding scheme), which is passed to the PHY layer, from higher layers, including the MAC layer, is contained in a TB having a size called a Transport Block Size (TBs), which is generally determined in units of bits. To calculate the CQI index for the channel, an exemplary procedure may be followed: measuring the CSI-RS and/or CRS to calculate a corresponding signal to interference plus noise ratio (SINR); and searching, based on the calculated SINR, a plurality of MCSs to determine which of the MCSs results in a BLER that meets a BLER threshold (e.g., below 0.1). When determining the BLER, the corresponding TBS needs to be estimated first. Therefore, in LTE networks, CQI indices are typically determined based on TBs.

However, in NR networks, when transmitting downlink data, TBs are typically further grouped (e.g., partitioned) into multiple Code Block Groups (CBGs) each having multiple Code Blocks (CBs). The UE provides ACK/NACK feedback using CBG. Therefore, in NR networks, the CQI index is typically determined based on CBGs rather than TBs.

In some embodiments, the BS informs the UE of the method by which the TB is divided into CBGs for CQI calculation. For example, the BS informs the UE of the number of CBGs required by the BS. According to the current standard in NR, the TB is equally divided into CBGs, so, depending on the number of CBGs, the UE will know the size of the CBGs from the TBs. The UE may then calculate a CQI index for each CBG. After the UE completes measuring the channel (e.g., by measuring CSI-RS), multiple combinations of MCS and TBS are available. When the UE searches for a suitable TBS that satisfies the BLER, the UE looks for a TBS that satisfies the number of notified CBGs based on the number of notified CBGs, and thus determines a corresponding MCS.

In the above embodiment, the UE may estimate a CQI index of at least one CBG satisfying the BLER criterion for the CBG based on the notified number of CBGs, and report such CQI index to the BS. Still in the above embodiments, the UE may estimate CQI indices for each CBG based on the number of CBGs notified and transform these CQI indices into one general CQI index for reporting. For example, in one embodiment, the UE may average all spectral efficiency/code rate values corresponding to each CQI index and report the CQI index whose corresponding spectral efficiency/code rate value is closest to the average spectral efficiency/code rate value.

It should be noted that the present invention is not limited to equal partitioning of TBs. For non-equal partitioning, the BS may inform the UE of more details about how the TB is partitioned into CBGs. For example, in some embodiments, the BS may inform the number of CBGs and the size of each CBG.

In another embodiment, the BS does not inform the UE that the BS allocates TBs for CQI derivation, and the UE determines a method for allocating the TBs itself based on data transmission support. For example, the UE determines the number of CBGs contained in the TB and the size of each CBG. Then, the UE estimates a CQI index of at least one of the CBGs for which the CQI index satisfies a BLER criterion and reports such CQI index to the BS together with the determined method, or estimates a CQI index of each of the CBGs, transforms all CQI indexes into one general CQI index, and reports such general CQI index to the BS together with the determined method.

In some embodiments, the UE determines the CQI index for the control channel based on a CQI calculation parameter that may be signaled by the BS or predefined by the protocol. For example, the BS indicates a control channel resource parameter (e.g., 2 symbols) to the UE, the UE determines a CQI index for the control channel based on the parameter, and transmits a corresponding CQI report to the BS.

As disclosed in the exemplary embodiments described above, the present invention provides various methods and systems for calculating a CQI index value. Fig. 3 shows a flow diagram of an exemplary process 300 that may utilize the techniques described above. At operation 301, the BS notifies the UE of at least one CQI calculation parameter set. In some embodiments, the at least one set of CQI calculation parameters is determined or selected from a plurality of predetermined sets of calculation parameters. At operation 303, the UE receives at least one CQI calculation parameter set from the BS. Next, at operation 305, the UE derives a CQI index value based on CQI calculation parameters in at least one set of CQI calculation parameters, and thereafter transmits a CQI report containing at least the CQI index value to the BS. At operation 307, the BS receives a CQI report from the UE. Based at least on the received CQI reports, the BS will selectively schedule transmissions to the UE in order to implement multiple-in multiple-out (MIMO) techniques, Adaptive Modulation and Coding (AMC) techniques, and/or optimal resource allocation based on the received CQI index values and other information contained in the CSI reports at operation 309.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Likewise, the various figures may depict example architectures or configurations provided to enable one of ordinary skill in the art to understand the example features and functionality of the present invention. However, such persons will appreciate that the invention is not limited to the example architectures or configurations shown, but can be implemented using a variety of alternative architectures and configurations. Furthermore, as one of ordinary skill in the art will appreciate, one or more features of one embodiment may be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

It will also be understood that any reference herein to an element using designations such as "first," "second," etc., does not generally limit the number or order of such elements. Rather, these designations may be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, reference to first and second elements does not mean that only two elements may be employed, or that the first element must somehow precede the second element.

In addition, those of ordinary skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, and symbols that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of ordinary skill would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods, and functions described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two), firmware, various forms of program or design code incorporating instructions (which may be referred to herein, for convenience, as "software" or a "software module"), or any combination of these technologies. To clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or combinations of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions do not depart from the scope of the present disclosure.

Furthermore, those of ordinary skill in the art will appreciate that the various illustrative logical blocks, modules, devices, components, and circuits described herein may be implemented within or performed by Integrated Circuits (ICs) that may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may also include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration for performing the functions described herein.

If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein may be embodied as software stored on a computer readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

The term "module" as used herein refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purposes of discussion, the various modules are described as discrete modules; however, it will be apparent to one of ordinary skill in the art that two or more modules may be combined to form a single module that performs the associated functions according to embodiments of the present invention.

Further, memory or other storage devices and communication components may be employed in embodiments of the present invention. It will be appreciated that for clarity purposes the above description has described embodiments of the invention with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processing logic elements or controllers may be performed by the same processing logic elements or controllers. Thus, references to specific functional units are only to references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the novel features and principles disclosed herein as recited in the following claims.

Claims (17)

1. A communication method performed by a first communication node, comprising:

notifying a second communication node of at least one set of channel quality indicator, CQI, calculation parameters, wherein the at least one set of CQI calculation parameters is determined from a plurality of sets of CQI calculation parameters, each set of CQI calculation parameters comprising at least one predefined CQI calculation parameter; and

receiving a CQI index value from the second communication node, the CQI index value derived based on CQI calculation parameters in the at least one set of CQI calculation parameters;

wherein the at least one set of CQI calculation parameters comprises at least one of the following parameters: a target block error rate BLER, a data resource mapping parameter, a number of downlink symbols per slot, a number of symbols occupied by a control channel, and a number of resource blocks RB; the at least one set of CQI calculation parameters is indicated by signalling from the first communication node to the second communication node.

2. The method of claim 1, wherein at least one set of CQI calculation parameters is indicated by first signaling from the first communication node to the second communication node, and the at least one set of CQI calculation parameters is identified in the at least one set of CQI calculation parameters by second signaling from the first communication node to the second communication node.

3. The method of claim 1, further comprising: notifying the second communication node of downlink slot information for identifying CSI reference resources.

4. The method of claim 3, further comprising: notifying the second communication node of uplink slot information for transmitting the CQI index value from the second communication node to the first communication node, the CQI index value corresponding to the CSI reference resource.

5. The method of claim 1, wherein the at least one set of CQI calculation parameters comprises information regarding a manner in which transport blocks for use as CSI reference resources are partitioned.

6. The method of claim 5, wherein the manner in which the transport block is partitioned comprises partitioning the transport block into a plurality of groups of code blocks.

7. The method of claim 1, wherein the CQI index value satisfies a condition that a block error rate, BLER, of a downlink channel block group, CBG, satisfies a BLER criterion.

8. A method performed by a second communication node, comprising:

receiving, from a first communication node, an identification of at least one set of Channel Quality Indicator (CQI) estimation parameters for deriving a CQI index value, wherein the at least one set of CQI calculation parameters is determined from a plurality of sets of CQI calculation parameters, each set of CQI calculation parameters comprising at least one predefined CQI calculation parameter;

deriving a CQI index value based on the at least one set of CQI calculation parameters; and

transmitting a CQI report to the first communication node;

wherein the at least one set of CQI calculation parameters comprises at least one of the following parameters: a target BLER, a rate matching parameter, a number of symbols per downlink slot, a number of physical downlink control channel, PDCCH, symbols, and a number of resource blocks; the at least one set of CQI calculation parameters is indicated by signalling from the first communication node to the second communication node.

9. The method of claim 8, wherein at least one set of CQI calculation parameters is indicated by first signaling from the first communication node to the second communication node, and the at least one set of CQI calculation parameters is identified in the at least one set of CQI calculation parameters by second signaling from the first communication node to the second communication node.

10. The method of claim 8, further comprising receiving an indication from the first communication node identifying a downlink slot for a CSI reference resource.

11. The method of claim 10, further comprising: receiving, from the first communication node, an indication of an uplink slot for transmitting the CQI index value to the first communication node, the CQI index value corresponding to the CSI reference resource.

12. The method of claim 8, wherein the at least one set of CQI calculation parameters comprises information regarding a manner in which transport blocks for use as CSI reference resources are partitioned.

13. The method of claim 12, wherein the manner in which the transport block is partitioned comprises partitioning the transport block into a plurality of groups of code blocks.

14. The method of claim 8, wherein the CQI index value satisfies a condition that a block error rate, BLER, of a downlink channel block group, CBG, satisfies a BLER criterion.

15. The method of claim 8, wherein the CQI report includes at least one of: CQI index value, and the way the transport block is divided.

16. A computing device configured to perform the method of any of claims 1-15; the computing device includes a transceiver module, a processor module, and a memory module.

17. A non-transitory computer-readable medium having stored thereon computer-executable instructions for performing the method of any of claims 1-15, the computer-executable instructions being executed by a computer device.

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