WO2019028879A1

WO2019028879A1 - System and method for determining a channel quality indicator (cqi) index value

Info

Publication number: WO2019028879A1
Application number: PCT/CN2017/097209
Authority: WO
Inventors: Cong Zhou; Hao Wu; Yu Ngok Li; Yijian Chen; Zhaohua Lu; Nan Zhang; Jun Xu
Original assignee: Zte Corporation
Priority date: 2017-08-11
Filing date: 2017-08-11
Publication date: 2019-02-14
Also published as: CN110999366A; CN110999366B

Abstract

A system and method for determining channel quality indicator (CQI) index values is disclosed. In one embodiment, a communication method performed by a first communication node, includes: informing a second communication node of at least one set of channel quality indicator (CQI) derivation parameters, wherein the at least one set of CQI derivation parameters is determined from a plurality of sets of CQI derivation parameters, each set of CQI derivation parameters comprising at least one predefined CQI derivation parameter; and receiving a CQI index value from the second communication node.

Description

SYSTEM AND METHOD FOR DETERMINING A CHANNEL QUALITY INDICATOR (CQI) INDEX VALUE

TECHNICAL FIELD

The disclosure relates generally to wireless communications and, more particularly, to systems and methods for determining channel quality indicator (CQI) index values for wireless communications.

BACKGROUND

Wireless networking systems have become a prevalent means by which a majority of people worldwide has 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, demanding reliable service and expanded areas of coverage.

A typical wireless communication network (e.g., employing frequency, time, and/or code division techniques) includes one or more base stations (typically known as a “BS” ) that each provides a geographical radio coverage, and one or more wireless user equipment devices (typically know as a “UE” ) that can transmit and receive data within the radio coverage. Such communication between the BS and UE can be degraded due to channel variations and/or interference and power variations. In this regard, the UE may use a pre-defined protocol and/or follow a higher-layer instruction to measure corresponding reference signal (s) so as to estimate channel conditions, which is typically represented as “channel state information (CSI) ” that is fed back to the BS. According to the CSI report from the UE, the BS can have a better knowledge of the channels and UE ability.

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

In a Long Term Evolution (LTE) network, the UE determines a CSI reference resource, which includes information about 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) , sent from the BS, the UE determines an index of the CQI (hereinafter “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. The periodic CQI report is 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 in the Physical Uplink Shared Channel (PUSCH) , together with UL data. This is because a UE cannot transmit on both PUCCH and PUSCH simultaneously. In this case, the periodic PUCCH resource will be idle. Since periodic CQI reports have an "always on" feedback overhead, the report granularity is relatively rough. In order to receive more detailed CQI reports, the BS (e.g., an eNB) can trigger aperiodic CQI reports when needed. The aperiodic CQI report is transmitted on PUSCH, together with UL data or alone.

The granularity of a CQI report can be divided into three levels: wideband, UE selected sub-band, and higher layer configured sub-band. The wideband report provides one CQI index value for the entire downlink system bandwidth. The UE selected sub-band CQI report divides the system bandwidth into multiple sub-bands, selects a set of preferred sub-bands (e.g., the best M sub-bands) , and then reports one CQI index value for the wideband and one differential CQI index value for the set of preferred sub-bands (assuming transmission over only the selected M sub-bands) . The higher layer configured sub-band report provides the highest granularity since it divides the entire system bandwidth into multiple sub-bands, and then reports one wideband CQI index value and multiple differential CQI index values, one for each sub-band.

In an LTE network, the UE receives a CSI measurement request, and then the UE determines a sub-frame to measure the CSI according to a pre-defined time offset relation and a condition to judge whether the sub-frame is a valid one. Among the measurements conducted to obtain the CSI, the measurement of CQI is conducted, as discussed further below. The CQI indices and their interpretations (i.e. a CQI index corresponds to a MCS level that consists of a set of parameters including modulation, code rate, and efficiency) are given in several pre-defined CQI tables for reporting CQI. The UE shall derive for each CQI value reported in an uplink subframe in the highest CQI index within a CQI Table which satisfies a predetermined condition.

For example, a single PDSCH transport block (TB) with a combination of modulation scheme and transport block size corresponding to the CQI index, and occupying a group of downlink physical resource blocks (RBs) termed the CSI reference resource, could be received with a transport block error probability (BLER) not exceeding 0.1 (i.e. the target BLER) . The UE shall derive the channel measurements for computing CQI based on a CRS and/or CSI-RS. Generally, the UE derives the SINR of the channel based on CRS/CSI-RS and calculates a respective BLER for each MCS level based on the SINR to see if the BLER < 0.1. To calculate the BLER, a PDSCH transport block size (TBS) is first determined. The TBS is determined by a number of RE’s (resource elements) that can be used to transmit data and a corresponding MCS level. Further, the number of RE’s available for transmitting data is defined by the “CSI reference resource, ” which depends on the group of downlink physical resource blocks to which the CQI derivation relates, and some assumptions about the CSI reference resource, as discussed further below.

In an LTE network, the UE uses a series of assumptions to determine the CSI reference resource. Some of the assumptions are: (1) the first 3 OFDM symbols are occupied by a PDCCH signal； (2) assume a CSI-RS and zero-power CSI-RS overhead for different transmission modes (TM) /configurations； (3) assume a DMRS overhead for different transmission modes (TM) /configurations； and (4) assume a CRS overhead for different transmission modes (TM) /configurations.

A conventional process for calculating a CQI index can be summarized as follows:

● Step 1: The UE measures the CRS and/or CSI-RS to get SINR.

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

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

● Step 4: The UE uses the pre-defined time offset, as mentioned above, to know a sub-frame index of the uplink sub-frame, and uses this uplink sub-frame to report the CQI index calculated in step 3.

● Step 5: The BS uses the CQI index to determine how to allocate resources and which MCS is to be used for subsequent downlink transmission.

In conventional techniques, as summarized above, to calculate the CQI index a UE must: (1) determine the CSI reference resource； and (2) know what the target BLER is. In LTE, the target BLER is fixed to 0.1, the assumptions to determine the CSI reference resource are also fixed in the protocol, as described above. Thus, the UE only needs to know the group of downlink resource blocks (RBs) to determine the CSI reference resource to calculate the CQI index.

In the New Radio (NR) network (e.g., the fifth-generation (5G) network) , however, due to various application demands (e.g., an ultra-reliable low-latency communication (URLLC) , a massive machine-type communication (mMTC) network, etc. ) and different protocols (e.g., a scalable transmission time interval (TTI) length, a variable number of symbols used by the PDCCH, etc. ) , the use of the above-mentioned conventional assumptions, which cannot be dynamically or semi-persistently configured (i.e., fixed) , may result in various problems such as, for example, an inaccurate and unreliable estimation of the CQI index value. Thus, existing systems and methods for estimating the CQI index value are not entirely satisfactory.

SUMMARY OF THE INVENTION

The exemplary embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the invention. In accordance with exemplary embodiments of the invention, one or more “CQI derivation parameters, ” which are used to determine the CSI reference resource, can be dynamically assigned by the BS to the UE, which is then used to determine the CQI index value.

In one embodiment, a communication method performed by a first communication node, includes: informing a second communication node of at least one set of channel quality indicator (CQI) derivation parameters, wherein the at least one set of CQI derivation parameters is determined from a plurality of sets of CQI derivation parameters, each set of CQI derivation parameters comprising at least one predefined CQI derivation parameter； receiving a CQI index value from the second communication node.

In a further embodiment, a method performed by a second communication node, includes: 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 derivation parameters is determined from a plurality of sets of CQI derivation parameters, each set of CQI derivation parameters comprising at least one predefined CQI derivation parameter； determining a CQI index value based on the at least one set of CQI derivation parameters； and transmitting the CQI report to the first communication node.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the invention are described in detail below with reference to the following Figures. 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. Therefore, the drawings should not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily drawn to scale.

Figure 1 illustrates an exemplary cellular communication network in which techniques disclosed herein may be implemented, in accordance with some embodiments of theinvention.

Figure 2 illustrates block diagrams of an exemplary base station and a user equipment device, in accordance with some embodiments of the invention.

Figure 3 illustrates a flowchart of an exemplary process for deriving a CQI index value, in accordance some embodiments of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various exemplary embodiments of the invention are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the invention. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the invention. Thus, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present invention. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the invention is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

Figure 1 illustrates an exemplary wireless communication network 100 in which techniques disclosed herein may be implemented, in accordance with various embodiments of the present disclosure. The exemplary communication network 100 includes a base station (BS) 102 and a user equipment (UE) device 104 that can communicate with each other via a communication link 110 (e.g., a wireless communication channel) , and a cluster of notional cells 126, 130, 132, 134, 136, 138 and 140 overlaying a geographical area 101. In Figure 1, the BS 102 and UE 104 are contained within the geographic boundary of cell 126. Each of the other cells 130, 132, 134, 136, 138 and 140 may include at least one base station operating at its allocated bandwidth to provide adequate radio coverage to its intended users. For example, the base station 102 may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE 104. The base station 102 and the UE 104 may communicate via a downlink radio frame 118, and an uplink radio frame 124 respectively. Each radio frame 118/124 may be further divided into sub-frames 120/126 which may include data symbols 122/128. In the present disclosure, the base station (BS) 102 and user equipment (UE) 104 are described herein as non-limiting examples of “communication devices, ” generally, which can practice the methods disclosed herein. Such communication devices may be capable of wireless and/or wired communications, in accordance with various embodiments of the invention.

Figure 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 invention. The 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, system 200 can be used to transmit and receive data symbols in a wireless communication environment such as the wireless communication environment 100 of Figure 1, as described above.

System 200 generally includes a base station 202 and a UE 204. The 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 module being coupled and interconnected with one another as necessary 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 module being coupled and interconnected with one another as necessary via a date communication bus 240. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium known in the art suitable for transmission of data as described herein.

As would be understood by persons of ordinary skill in the art, system 200 may further include any number of modules other than the modules shown in Figure 2. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in 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 are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present invention.

In accordance with some embodiments, UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 that includes a RF transmitter and receiver circuitry that are each coupled to the antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210 that includes RF transmitter and receiver circuity that are each coupled to the antenna 212. A downlink duplex switch (not shown) may alternatively couple the downlink transmitter or receiver to the downlink antenna 212 in time duplex fashion. The operations of the two

transceivers

210 and 230 are coordinated in time such that the uplink receiver is coupled to the uplink antenna 232 for reception of transmissions over the wireless transmission link 250 at the same time that the downlink transmitter is coupled to the downlink antenna 212. Preferably there is close time synchronization with only a minimal guard time between changes in duplex direction.

The UE transceiver 230 and the base station transceiver 210 are configured to communicate via the wireless data communication link 250, and cooperate with a suitably configured RF antenna arrangement 212/232 that can support a particular wireless communication protocol and modulation scheme. In some exemplary embodiments, the UE transceiver 608 and the base station transceiver 602 are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G standards, and the like. It is understood, however, that the invention is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

In accordance with various embodiments, the BS 202 may be an evolved node B (eNB) , a serving eNB, a target eNB, a femto station, or a pico station, for example. In some embodiments, the UE 204 may be embodied in various types of user devices such as a mobile phone, a smart phone, a personal digital assistant (PDA) , tablet, laptop computer, wearable computing device, etc. The processor modules 214 and 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 realized as a microprocessor, a controller, a microcontroller, a 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 processor modules 214 and 236, respectively, or in any practical combination thereof. The

memory modules

216 and 234 may be realized 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,

memory modules

216 and 234 may be coupled to the

processor modules

210 and 230, respectively, such that the

processors modules

210 and 230 can read information from, and write information to,

memory modules

216 and 234, respectively. The

memory modules

216 and 234 may also be integrated into their

respective processor modules

210 and 230. In some embodiments, the

memory modules

216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by

processor modules

210 and 230, respectively.

Memory modules

216 and 234 may also each include non-volatile memory for storing instructions to be executed by the

processor modules

210 and 230, respectively.

The network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 202 that enable bi-directional communication between base station transceiver 602 and other network components and communication devices configured to communication with the base station 202. For example, network communication module 218 may be configured to support internet or WiMAX traffic. In a typical deployment, without limitation, network communication module 218 provides an 802.3 Ethernet interface such that base station transceiver 210 can communicate with a conventional Ethernet based computer network. In this manner, the network communication module 218 may include a physical interface for connection to the computer network (e.g., Mobile Switching Center (MSC) ) . The terms “configured for, ” “configured to” and conjugations thereof, as used herein with respect to a specified operation or function, 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 Figure 1, as discussed above, when the BS 102 is preparing to transmit and receive data from the UE 104, a channel estimation process is typically performed before the BS actually transmits and receives the data from the UE 104. During such a channel estimation process, one or more reference signals (e.g., a CSI-RS and/or CRS) are typically transmitted from the BS 102 to the UE 104 via one or more physical channels. According to measurements on the reference signals, the UE 104 determines a CQI index and sends a CQI report containing the CQI index back to the BS 102.

In accordance with various embodiments, a method to derive a CQI index using various sets of “CQI derivation parameters” is disclosed. Different from the LTE network that relies on the fixed set of assumptions (i.e., the 7 assumptions discussed above) , in some embodiments, such various sets of CQI derivation parameters can provide respective different sets of assumptions to allow the BS to determine respective CSI reference resources for different scenarios/applications that will arise in NR networks. More specifically, in some embodiments, based on one of various scenarios/applications, the BS may inform the UE of a CQI derivation parameter set, and the UE may determine a respective CSI reference resource to derive a CQI index based on the CQI derivation parameters contained in the set, so that the BS can more accurately interpret the CQI index using the information that it conveyed to the UE.

In accordance with some embodiments, a table that includes a plurality of CQI indexes each associated with respective one of a plurality of CQI derivation parameters is provided, as shown in Table 2 below. As shown in Table 2, the first column represents the CQI index； the second column represents the number of symbols (e.g., OFDM symbols) of each downlink slot； the third column represents the number of first symbols (e.g., OFDM symbols) in each resource block that are occupied by a control channel； the fourth column represents rate matching parameters； and the fifth column represents a target Block Error Rate (BLER) . It is understood that the invention is not limited to the exemplary estimation parameters shown in Table 2 below. In other embodiments, further CQI derivation parameters (e.g., a number of resource blocks, a data resource mapping parameter, a number of downlink symbols per slot, and a control channel resource parameter) may be added as columns in the table below, or replace one or more columns 2-5 in the table below. Additionally, it is understood that values contained in Table 2 below are exemplary only and other values may be utilized in a NR system, for example, to provide various joint coding techniques, in accordance with various embodiments of the invention. For another example, control channel resource information including time domain (e.g. the number of symbols) and the frequency domain (e.g. the groups of RBs or REs) can replace column 3 of Table 2 below.

TABLE 2

In some embodiments, the BS 102 informs the UE 104 of one set of the CQI derivation parameters through various methods. For example, the BS 102 can inform the UE 104 of CQI derivation parameter index value as shown in Table 2 above through a signaling, e.g., a Radio Resource Control (RRC) instruction having 4 bits, a Medium Access Control (MAC) signal, etc. Thus, the UE 104 can obtain the corresponding CQI derivation parameters according to the CQI Derivation Parameter (CQIDP) Index value. In another example, the above Table 2 is grouped into plural groups, for example, a first group having the sets corresponding to the CQIDP indexes from 0 to 7, and a second group having the sets corresponding to the CQIDP indexes from 8 to 14. The BS 102 first informs the UE 104 which group through a first signaling with fewer bits (e.g., a RRC/MAC signal having 1 bit) , and then within the group, the BS informs which set through a second signaling, e.g., a Downlink Control Information (DCI) signal having 3 bits. As discussed above, however, the values in Table 2 are merely exemplary and various values and parameters may be used instead of those in Table 2 depending on various system requirements and/or applications, in accordance with various embodiments.

Second, the BS 102 informs the UE 104 which CSI reference resource the UE 104 can use for estimating the CSI index. In some embodiments, the BS 102 informs the UE 104 where the resources are located along a time domain, for example, which of the downlink slots/mini-slots the CSI reference resource is located in. In some embodiments, a time offset relationship (n-n_{CQI_ref}) between the downlink slot/mini-slot and an uplink slot/mini-slot is provided, wherein “n” represents an index of the uplink slot/mini-slot and “n_{CQI_ref}” represents the time offset. In some embodiments, the relationship is determined by the BS and conveyed to UE. Specifically, the BS can determine this relationship by configuring the time offset and conveying it to UE through a signal (e.g. a RRC/MAC/DCI signal) . Furthermore, a time offset can be determined by the BS from a pre-defined set of time offset values (e.g. 2, 3, 4, and 5) and thereafter conveyed to the UE. There are various factors that can effect this determination. For example, in a URLLC scenario, the BS may have a need of a shorter offset (e.g., 2) so that the CQI report is more reliable (since it represents the quality of a channel from just 2 ms before) . In other embodiments, the relationship is pre-defined. For example, n-n_{CQI_ref}is a specific one of various slots/mini-slots.

In some embodiments, two or more parameter sets as shown in exemplary Table 2 above can be configured through high-layer signaling by BS, and at least one set can be triggered by the DCI signal. The UE uses the at least one set to determine a respective CQI index and report the respective CQI indexes to the BS. In some embodiments, since the two CQI indexes imply the BLER of two kinds of CSI reference resource, the BS can consider these two CQI indexes and get more information, e.g., the channel state information and UE ability. In some embodiments, to reduce resource usage for instruction, part of the CQI derivation parameters can be pre-configured without signaling from a BS to a UE. Further, such a pre-configuration can be a specific value for a CQI derivation parameter, or can be a mapping rule/relationship between a CQI derivation parameter and other configurations/conditions. For example, BS and UE can first agree on a number of OFDM symbols occupied by PDCCH (e.g. 2) , agree on a mapping rule between DMRS REs and the RI value which the UE recent use, agree on a mapping rule between the target BLER and the length of the slot. For example, the BS and UE can be pre-configured (i.e., agree that) : at a certain configuration of the sub-carrier interval (e.g. 15KHz, ) , when the length of a slot <7, then the target BLER＝0.01, and when the length of a slot >＝7, the target BLER＝0.1. Thus, the BS only need to configure the number of OFDM symbols (i.e., the second column in Table 1) for the UE to derive a CQI index value.

In NR, the scheduling unit in time domain is slot or mini-slot, so the CSI reference resource definition of a time domain should also be based on slot or mini-slot. In NR, one slot/mini-slot contains a predetermined number of OFDM symbols, e.g. from 1 to 14, in contrast to LTE systems, in which one slot contains 7 symbols (Normal CP) , for example. In accordance with a first method for NR communications, the BS may set a threshold (e.g., K0 ＝ 7) among available numbers (e.g. 1～14 ) of OFDM symbols in each slot. When the UE measures a number of its respective CSI reference resources are more than K0, the UE uses a K1 number of OFDM symbols to estimate the CQI index； and when the UE measures a number of its respective CSI reference resources are less than K0, the UE uses a K2 number of OFDM symbols to estimate the CQI index, , wherein K0, K1, and K2 are integer values. The UE can determine the K0, K1 and K2 according to a pre-determined protocol established with the BS or a indicator signal from the BS. For example, if K0 belongs to {4, 7} , the specific value of K0 is configured by the BS through one 1 bit signaling, and the UE can determine K1 in accordance with a predetermined relationship or algorithm (e.g., K0＝K1) , and can determine K2 where K2 equals the actual number of OFDM symbols of CSI reference resource, for example.

In accordance with a second method, the BS may divide all available numbers (1～14 in theory) of OFDM symbols in each slot into plural subsets, wherein each subset has an M number of OFDM symbols and a last (remaining) subset may have a number of OFDM symbols less than M. When the UE measures a number of OFDM symbols of its respective CSI reference resource is equal to one of the numbers of OFDM symbols within a subset, the UE uses an average of the numbers of OFDM symbols, and rounds up if necessary, within the subset to estimate the CQI index. For example, when M＝5, the numbers of OFDM symbols may be divided into subsets: {1, 2, 3, 4, 5} , {6, 7, 8, 9, 10} , and {11, 12, 13, 14, 15} with averages 3, 8, and 13, respectively. And when a number of OFDM symbols of a CSI reference resource is 4 (falling into the first subset) , the UE then uses the average of the first subset, 3, to estimate the CQI index. In some embodiments, the UE can determine M based on a predetermined arrangement or agreement with the BS or, alternatively, based on an indicator signal from BS.

In accordance with a third method, the BS can determine the number of OFDM symbols for CQI derivation from a set of values (e.g., {4, 7, 10, 14} ) which is pre-defined, and conveys it to the UE (e.g. through 2 bits signaling) . This method is a special case of the embodiment described above with only the first two columns remaining in Table 2.

In accordance with some embodiments, one or more of the CQI derivation parameters can be pre-configured as a fixed value. For example, the estimation parameter of “number of symbols” as shown in the second column of Table 2 above may be pre-configured as 2. In some embodiments, the BS and UE can also pre-establish the method to determine the parameter. For example, the UE can determine the CQI estimate parameters according the actual parameters of the CSI reference resource.

In some embodiments, , the above-mentioned CSI reference resource that may be used by the UE to estimate the CQI index is also limited by the CQI derivation parameters. In other words, in such an embodiment, the CSI reference resource needs to satisfy each of the CQI derivation parameters contained in the informed assumption, and if the UE cannot find a slot/mini-slot, for example, meeting all the CQI derivation parameters of a defined set of parameters corresponding to a respective CQI index value, the UE will not report a CQI index value to the BS.

In the LTE network, when data (e.g., downlink data) is transmitted, a notation of a Transport Block (TB) is used. Generally, the data from higher layers, including the MAC layer to select the MCS (Modulation and Coding Scheme) , that is passed on to the PHY layer is contained in a TB having a size, referred to as a Transport Block Size (TBS) typically determined in units of bits. To compute a CQI index of a 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 based on the calculated SINR, searching a plurality of MCS’s to determine which of the MCS’s yields a BLER that satisfies a BLER threshold (e.g., lower than 0.1) . When determining the BLER, a respective TBS needs to be estimated first. Thus, in the LTE network, the CQI index is generally determined based on the TB.

In the NR network, however, when downlink data is transmitted, the TB is typically further grouped (e.g., divided) into plural Code Block Groups (CBG) that each has a plurality of Code Blocks (CBs) . The UE uses the CBG to provide an ACK/NACK feedback. Accordingly, in the NR network, the CQI index is generally determined based on the CBG, instead of the TB.

In some embodiments, the BS informs the UE of the method that the TB is divided into CBG’s for CQI calculation. For example, the BS informs the UE of the number of CBG’s that the BS needs. Based on the current standard in NR, the TB is equally divided to plural CBG’s so given the number of CBG’s, the UE will know the size of the CBG according to the TBS. Then, the UE can calculate the CQI index for each CBG. After the UE finishes measuring the channel (by measuring the CSI-RS, for example) , a plurality of combinations of the MCS and the TBS are available. When the UE searches for a suitable TBS that meets the BLER, the UE, based on the informed number of the CBGs, looks for a TBS that satisfies the informed number of the CBGs, and thus determines a corresponding MCS.

In the above embodiment, the UE may, based on the informed number of the CBGs, estimate a CQI index for at least one CBG that satisfies a BLER criterion for that CBG, and report such CQI index to the BS. Still in the above embodiment, the UE may, based on the informed number of the CBGs, estimate a CQI index for each of the CBGs, and transform these CQI indexes into one general CQI index for reporting. For example, in one embodiment, the UE can average all the spectrum efficiency/code rate values corresponding to each CQI index, and report a CQI index whose corresponding spectrum efficiency/code rate value is nearest to the averaged spectrum efficiency/code rate value.

It is noted that the current invention is not limited to an equal division of the TB. For non-equal division, the BS can inform the UE of more details concerning how the TB is divided into the CBG’s. For example, in some embodiments, the BS may inform the number of the CBGs and the size of each of the CBGs.

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

In some embodiment, the UE determines a CQI index of a control channel based on the CQI derivation parameters which can be signaled by the BS or be pre-defined 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 a control channel based on the parameter and sends a respective CQI report to the BS.

As disclosed in the exemplary embodiments described above, various methods and systems for calculating a CQI index value are provided by the invention. Figure 3 illustrates a flowchart of an exemplary process 300 that can utilize the techniques discussed above. At operation 301, a BS informs a UE of at least one CQI derivation parameter set. In some embodiments, the at least one CQI derivation parameter set is determined or selected from a plurality of predetermined derivation parameter sets. At operation 303, the UE receives the at least one CQI derivation parameter set from the BS. Next, at operation 305, the UE derives a CQI index value based on CQI derivation parameters of the at least one CQI derivation parameter set and thereafter transmits a CQI report containing at least the CQI index value to the BS. At operation 307, the BS receives the CQI report from the UE. At operation 309, based at least on the received CQI report, the BS will schedule transmissions to the UE selectively, so as to facilitate realization of Multi-Input-Multi-Output (MIMO) techniques, Adaptive Modulation and Coding (AMC) techniques, and/or optimal resource allocation based on the received CQI index value and other information contained in the CSI report.

While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand exemplary features and functions of the invention. Such persons would understand, however, that the invention is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can 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 is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

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

A person of ordinary skill in the art 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 can be implemented by 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 can be referred to herein, for convenience, as "software" or a "software module) , or any combination of these techniques. 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 a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can 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 logical blocks, modules, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can 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 to perform the functions described herein.

If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented 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 can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include 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.

In this document, 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 purpose of discussion, the various modules are described as discrete modules； however, as would be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs the associated functions according embodiments of the invention.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the 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 element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the scope of this disclosure. Thus, the 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 claims below.

Claims

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

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

receiving a CQI index value from the second communication node.
The method of claim 1, wherein the at least one set of CQI derivation 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 control channel and a number of resource blocks (RBs) .
The method of claim 1, wherein the at least one set of CQI derivation parameters is indicated by a signaling from the first communication node to the second communication node.
The method of claim 1, wherein a group of CQI derivation parameter sets is indicated by a first signaling from the first communication node to the second communication node and the at least one set of CQI derivation parameters is identified among the group by a second signaling from the first communication node to the second communication node.
The method of claim 1, further comprising: informing the second communication node of a downlink time slot used to identify a CSI reference resource.
The method of claim 5, further comprising informing the second communication node of an uplink time slot for transmitting the CQI index value corresponding to the CSI reference resource from the second communication node to the first communication node.
The method of claim 1, wherein the at least one set of CQI derivation parameters comprises information concerning a manner of dividing a transport block for use as the CSI reference resource.
The method of claim 7 wherein the manner of dividing the transport block comprises dividing the transport block into a plurality of code block groups.
The method of claim 1, wherein the CQI index value satisfies a condition that a block error rate (BLER) of a downlink channel code block group (CBG) meets a BLER criterion.
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 derivation parameters is determined from a plurality of sets of CQI derivation parameters, each set of CQI derivation parameters comprising at least one predefined CQI derivation parameter；

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

transmitting a CQI report to the first communication node.
The method of claim 10, wherein the at least one set of CQI derivation 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 method of claim 10, wherein the at least one set of CQI derivation parameters is indicated by a signaling from the first communication node to the second communication node.
The method of claim 10, wherein a group of CQI derivation parameter sets is indicated by a first signaling from the first communication node to the second communication node and the at least one set of CQI derivation parameters is identified among the group by a second signaling from the first communication node to the second communication node.
The method of claim 10, further comprising receiving from the first communication node an indication of a downlink time slot used to identify a CSI reference resource.
The method of claim 14, further comprising receiving from the first communication node an indication of an uplink time slot for transmitting the CQI index value corresponding to the CSI reference resource to the first communication node.
The method of claim 10, wherein the at least one set of CQI derivation parameters comprises information concerning a manner of dividing a transport block for use as the CSI reference resource.
The method of claim 16 wherein the manner of dividing the transport block comprises dividing the transport block into a plurality of code block groups.
The method of claim 10, wherein the CQI index value satisfies a condition that a block error rate (BLER) of a downlink channel code block group (CBG) meets a BLER criterion.
The method of claim 10, wherein the CQI report comprises at least one of the following information: a CQI index value, and a manner of dividing a transport block.
A computing device configured to carry out the method of any one of claims 1 through 19.
A non-transitory computer-readable medium having stored thereon computer-executable instructions for carrying out the method of any one of claims 1 through 19.