KR102341171B1 - Method and Device for Measuring and Reporting Channel State Information - Google Patents

Abstract

The present disclosure relates to a 5G or pre-5G communication system to be provided to support a higher data rate after a 4G communication system such as LTE. The present application discloses a method and device for measuring and reporting channel state information (CSI). One embodiment of the method for measuring and reporting the CSI includes: a user terminal (UE) measuring the CSI in multiple types of downlink signals; and feeding back, by the UE, measured CSI based on the plurality of types of downlink signals. By using embodiments of the present invention, in addition to allowing the CSI measurement in multiple types of downlink signals, the opportunities for the UE to measure the CSI are increased, the accuracy of the CSI measurement is improved, The most efficient CSI can be fed back.

Description

Method and Device for Measuring and Reporting Channel State Information

The present disclosure relates to the field of wireless communication technology, and more particularly, to a method for feeding back channel state information (CSI), a user device, and a base station.

^{Efforts are being made to develop an improved 5G (5 th} -Generation) communication system or pre-5G communication system to meet the increasing demand for wireless data traffic after commercialization of the 4G (4 ^{th -Generation) communication system.} . For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) or after the LTE system (Post LTE).
In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, in the 5G communication system, beamforming, massive multi-input multi-output (massive MIMO), and all-dimensional multiple input/output are used. (Full Dimensional MIMO: FD-MIMO), array antenna (array antenna), analog beam-forming (analog beam-forming), and large-scale antenna (large scale antenna) technologies are being discussed.
In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network: cloud RAN), an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway.
In addition, in the 5G system, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technologies FBMC (Filter Bank Multi Carrier), NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.
With sharp conflicts between users' explosive demands in high bandwidth wireless services and growing scarcity of spectrum resources, the mobile operators are turning to unlicensed bands as complements to licensed bands. Start considering using them. Therefore, deploying LTE in the unlicensed bands has been on the agenda.
1 shows a schematic diagram of the aggregation of the licensed and unlicensed bands.
As shown in FIG. 1 , a plurality of small cells or Wireless Fidelity (WiFi) access points (APs) may exist within the coverage of a macro cell. These small cells or WiFi APs may use licensed bands and unlicensed bands (ie, licensed bands and unlicensed bands) in a carrier aggregation manner. The 3rd Generation Partnership Project (3GPP) describes how to efficiently increase the utilization rate of the entire network by using efficient carrier aggregation of the unlicensed and licensed bands without seriously affecting other technologies in the unlicensed band. Started research on how to improve it.
In general, the unlicensed bands have been distributed for some other use, such as radar or WiFi of the 802.11 series. As described above, the interference level in the unlicensed bands is not determined, so it is not easy to ensure that LTE transmission ensures good Quality of Service (QoS). However, the unlicensed bands can be used at least for data transmission requiring low QoS. Here, the LTE system disposed in the unlicensed band is referred to as an LTE-U system. How to prevent radar or other wireless systems such as WiFi and LTE-U systems from interfering with each other is an important issue. Clear Channel Assessment (CCA) is a mechanism commonly used in the unlicensed bands to avoid collisions. A mobile station (STA) must detect a radio channel before transmitting signals, and can occupy the radio channel and transmit signals only when it detects that the radio channel is idle. The LTE-U should also follow a similar mechanism to ensure less interference with other signals, such as: A relatively easy way is for the LTE-U device (base station or terminal user) to dynamically switch according to the CCA results. That is, transmission is performed when it is monitored that the channel is idle, and the transmission is not performed when the channel is busy.
In the LTE system, particularly in the downlink, the UE reports downlink Channel State Information (CSI) to the base station to support a link self-adaptation function at the base station side. Needs to be. The UE includes a cell specific reference signal (CRS), a non-zero power channel state information reference signal (NZP-CSI-RS), or a zero-power CSI-RS The quality of the channel is measured based on (Zero-Power CSI-RS: ZP-CSI-RS), and a Channel Quality Indicator (CQI) is reported to the base station. The UE may report the CQI periodically, or may report the CQI aperiodically under triggering of the base station. Current downlink pilot signals for measuring the channel quality are transmitted periodically. Accordingly, the UE may acquire and combine one or more samples related to the channel quality based on these signals to generate a corresponding CQI to be reported to the base station.
In the unlicensed bands, since the LTE-U device switches dynamically according to the CCA results to decide whether to transmit signals or not, the LTE-U device cannot transmit any signal for a long time. Therefore, the UE cannot measure the channel strength of the CSI based on the pilot signal. When the CQI reported by the UE is based on a channel strength measured a long time ago, the channel strength at the time when the UE reports the CQI cannot be accurately reflected. In addition, other wireless communication systems around the base station generally exist in a temporarily closed state in which no signal is transmitted when the UE is scheduled by the LTE-U base station, and other wireless communication systems around the base station The levels of interference in these two situations are different, since communication systems may be in an open state in which signals are transmitted if the LTE-U base station does not occupy carrier resources in unlicensed bands. Only when the CQI reported by the UE can accurately reflect the channel quality at the time when the LTE-U base station schedules the UE, the CQI can provide a more accurate reference for the scheduling of the base station. To help the base station schedule users with high efficiency, ensuring that the CQI reported by the UE at the time the LTE-U base station schedules the UE accurately reflects the channel quality is still an unresolved problem .
It should be noted that the above description of the prior art part has been described only for the purpose of clearly and completely illustrating the technical solution of the present invention and for enabling the understanding of those skilled in the art. . It should not be considered that the technical solutions as described above are known to those skilled in the art simply because these solutions are described in the prior art part of the present invention.

The present application provides a method and a user terminal for measuring and reporting channel state information (CSI).
The present application provides a method and device for measuring and reporting CSI in a Long Term Evolution (LTE) system.

In one aspect, a method for measuring and reporting channel state information (CSI) is provided. The method includes: a user terminal (UE) measuring the CSI in a plurality of downlink signals; and feeding back, by the UE, the CSI measured based on the plurality of types of downlink signals.
In some embodiments, the CSI is measured based on at least one type of downlink signals, the at least one type of downlink signals being: by the base station within a time period during which the base station transmits downlink data. a reference signal for CSI measurement to be transmitted; a discovery reference signal (DRS) transmitted by a base station; Specific to CSI measurement, characterized in that it is selected from the group consisting of a reference signal transmitted by a base station.
In some embodiments, the method includes: the UE indicating to the base station that the CSI is not valid if no signal transmitted by the base station is received by the UE within a predetermined time period ; Otherwise, the method further includes the step of indicating, by the UE, a current channel interference level to the base station. In some embodiments, the process by the UE indicating the current channel interference level to the base station is: a window configured by the base station for the UE to measure the CSI by the signal transmitted by the base station and feeding back a pure interference level indicator to the base station only when it is not received within.
In some embodiments, measuring the CSI based on the DRS transmitted by the base station includes: directly using the DRS as a reference signal for measuring the CSI; a process of using a plurality of reference signal ports included in the DRS after the extension of the DRS; It characterized in that it includes any one of the process of performing the CSI measurement based on the reference signal for the CSI measurement configured in the DRS through high layer signaling.
In some embodiments, the process of using the plurality of reference signal ports included in the DRS after the extension of the DRS is: Extension and inclusion of all or some sub-frames of the DRS for the CSI measurement The process of using a plurality of CRS ports to be; It characterized in that it includes at least one of a process of using a plurality of CSI-RS ports extended and included in all or some of the subframes of the DRS for the CSI measurement.
In some embodiments, the higher layer signaling is characterized in that it configures a cycle (cycle), an offset (offset) and a duration (duration) of the cell common reference signal for the CSI measurement.
In some embodiments, the process in which the UE feeds back the measured CSI based on the multiple types of downlink signals: Occurs in occupying the same resource to feed back multiple CSIs of an unlicensed band and feeding back the CSI according to a predetermined priority if necessary, wherein the predetermined priority is: A priority in which validity of CSI measured based on the plurality of types of downlink signals is the highest. to have; The CSI report type has the highest priority, and the priority of the validity of CSI measured based on the plurality of types of downlink signals is only lower than the priority of the CSI report type. characterized.
In some embodiments, the process of the UE feeding back the CSI measured based on the plurality of types of downlink signals is: To feed back CSI of an unlicensed band and CSI of a licensed band determining the priority according to the type of the band when occupying the same resource occurs; or aligning the CSI of the unlicensed band and the CSI of the licensed band according to validity, wherein the CSI of the licensed band has a predetermined validity.
In some embodiments, the predetermined validity of the CSI of the licensed band is: the validity of the CSI of the licensed band is higher than the CSI of the unlicensed band measured based on the plurality of types of downlink signals; that the validity of the CSI of the licensed band is lower than the CSI of the unlicensed band measured based on the plurality of types of downlink signals; The validity of the CSI of the licensed band is lower than the CSI of the unlicensed band measured based on the plurality of types of downlink signals, but is higher than the CSI measured based on a reference signal specific to the DRS and CSI measurement. It is characterized in that it includes.
In some embodiments, the step of feeding back the CSI measured based on the plurality of types of downlink signals by the UE further comprises: the UE reporting identification information of the fed back CSI, the identification The information is characterized in that it includes at least one of a corresponding cell identifier, a CSI process identifier, and a CSI validity type.
In some embodiments, the process of the UE feeding back CSI measured based on the plurality of types of downlink signals includes: feeding back only CSI measured based on one type of downlink signal in one CSI process It is characterized in that it further includes a process.
In some embodiments, the process of the UE feeding back the CSI measured based on the multiple types of downlink signals includes: feeding back the CSI measured based on the multiple types of downlink signals in one CSI process It is characterized in that it further includes a process.
In some embodiments, when feeding back CSI measured based on the plurality of types of downlink signals in the one CSI process, the interference component of the CSI measurement is: the interference only in subframes of signals of the same type how to perform an averaging operation on the component measurements; in such a manner that no averaging operation is performed on the measurement of the interference component; and performing a weighted averaging of the measurement of the interference component based on interference levels corresponding to different types of downlink signals.
In some embodiments, when feeding back CSI measured based on the multiple types of downlink signals in one CSI process, the compensating operation is performed according to the interference levels corresponding to the different types of downlink signals. It is characterized in that it is performed on CSI measured based on downlink signals of different types.
In some embodiments, the compensating operation comprises: the UE determines the interference level A in a period in which the base station transmits downlink data, and a period in which the base station transmits a reference signal specific to the DRS or the CSI measurement determining an interference level B in , and then compensating, by the UE, a signal-to-noise ratio obtained from the CSI measurement of the UE according to the interference level A and the interference level B; Increasing the power of the channel component obtained from the CSI measurement corresponding to the high interference level by a predetermined value, or increasing the power of the interference component obtained from the CSI measurement corresponding to the high interference level by the predetermined value It is characterized in that it includes any one of decreasing by a value.
In some embodiments, the process of the UE feeding back the CSI measured based on the plurality of types of downlink signals is: according to a signal type based on the most recently reported Rank Indication (RI). A method of feeding back a pre-coded matrix indicator/channel quality indicator (PMI/CQI) of all bandwidth parts (Bandwidth Part: BP) in the entire bandwidth based on the same type of signal class; a method of feeding back the PMI/CQI of each BP based on a downlink signal of a channel most recently occupied by the base station, where it is assumed that RI is the same as the most recently reported RI; When the priority of the new signal type useful for measuring the CSI is higher than the previous signal type, the PMI/CQI of each BP is fed back based on the downlink signal of the channel most recently occupied by the base station; where RI is assumed to be the same as the most recently reported RI; When the priority of the new signal type useful for measuring the CSI is higher than the previous signal type, from the Physical Uplink Control Channel (PUCCH) resource that satisfies the process delay, the PMI/CQI of each BP and The method further comprises the step of feeding back the RI and PMI/CQI of each BP subband according to any one of the methods for feeding back the RI measured based on the new signal type.
In a second aspect, a method for receiving channel state information (CSI) is provided. The method includes: a base station transmitting a plurality of types of downlink signals for CSI measurement; and receiving CSI fed back by a user equipment (UE) and measured based on the plurality of types of downlink signals.
In some embodiments, the plurality of types of downlink signals include: a reference signal for CSI measurement transmitted within a time period during which the base station transmits downlink data; Discovery Reference Signal (DRS); It is characterized in that it includes at least one of the reference signals specified for CSI measurement.
In some embodiments, the step of transmitting the DRS for the CSI measurement includes: directly using the DRS as a reference signal for the CSI measurement; extending the DRS to include a plurality of reference signal ports for the CSI measurement; and configuring the reference signal for the CSI measurement in the DRS through higher layer signaling.
In some embodiments, the process of receiving CSI fed back by the UE and measured based on the plurality of types of downlink signals includes: being measured based on one type of downlink signal in one CSI process The process of receiving only CSI; or receiving CSI measured based on the plurality of types of downlink signals in one CSI process.
In some embodiments, when receiving CSI measured based on the plurality of types of downlink signals in the one CSI process, the method includes: according to interference levels corresponding to different types of downlink signals , constructing signal power estimates of the CSI measurement based on each of different types of downlink signals; or instructing the UE to increase the power of the channel component obtained from the CSI measurement corresponding to the high interference level by a predetermined value, or the power of the interference component obtained from the CSI measurement corresponding to the high interference level It characterized in that it further comprises the process of reducing by the predetermined value.
In a third aspect, a user terminal is provided. the user terminal includes a receiver, a transmitter and a processor, the receiver being configured to receive multiple types of downlink signals from a base station; the processor is configured to measure Channel State Information (CSI) in the plurality of types of downlink signals; The transmitter is configured to feed back the CSI measured based on the plurality of types of downlink signals to the base station.
In a fourth aspect, a base station is provided. the base station includes a receiver, a transmitter and a processor, wherein the transmitter is configured to transmit multiple types of downlink signals for CSI measurement under the control of the processor; The receiver is configured to receive the CSI fed back by a user equipment (UE) and measured based on a plurality of types of downlink signals.
It should be noted that corresponding embodiments of the first aspect are also applicable to the second aspect. Similarly, it should be noted that corresponding embodiments of the second aspect are also applicable to the fourth aspect.
A specific embodiment described according to the present application makes it possible for the UE to increase the chances of measuring CSI, improve the accuracy of the CSI measurement, and feed back the most effective CSI.

Other aspects, features and benefits as described above of certain preferred embodiments of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
1 shows a schematic diagram of an aggregation of a licensed band and an unlicensed band.
2 is a diagram illustrating a CSI measurement and reporting method according to an embodiment of the present application.
3 shows a schematic diagram of the structure of a DRS.
4 shows a schematic diagram of a preferred structure in which the DRS is expanded to include a plurality of CRS ports.
5 shows a schematic diagram of another preferred structure in which the DRS is extended to include a plurality of CRS ports.
6 shows a schematic diagram of another preferred structure in which the DRS is extended to include a plurality of CRS ports.
7 shows a schematic diagram of another preferred structure in which the DRS is extended to include a plurality of CRS ports.
8 shows a schematic diagram of interference dispersion of the UE when the base station transmits downlink signals in different scenes.
9 shows a preferred schematic diagram for feeding back P-CSI based on priority.
10 illustrates situations that may occur when CSI is fed back due to CSI measured based on different types of signals.
11 shows a preferred schematic diagram of feedback RI and each BP.
12 shows a preferred schematic diagram of feeding back different RIs and each BP.
13 shows a preferred schematic diagram of feeding back different RIs and each BP.
14 is a schematic flowchart of a method for receiving CSI according to an embodiment of the present application.
15 shows a schematic diagram of a device that may be used to implement a preferred embodiment of the present application.
It should be noted that throughout the drawings, like reference numerals are used to denote the same or similar elements, features, and structures.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention without obscuring the gist of the present invention by omitting unnecessary description.
For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. In addition, the size of each component does not fully reflect the actual size. In each figure, the same or corresponding elements are assigned the same reference numerals.
Advantages and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.
At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment are not described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory which may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It is also possible that the instructions stored in the flow chart block(s) produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in the flowchart block(s).
Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations it is also possible for the functions recited in blocks to occur out of order. For example, two blocks shown one after another may be performed substantially simultaneously, or the blocks may sometimes be performed in the reverse order according to a corresponding function.
In this case, the term '~ unit' used in this embodiment means software or hardware components such as field-programmable gate array (FPGA) or ASIC (Application Specific Integrated Circuit), and '~ unit' refers to what role carry out the However, '-part' is not limited to software or hardware. '~' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Accordingly, as an example, '~' indicates components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card.
In describing the embodiments of the present disclosure in detail, the OFDM-based wireless communication system will be mainly targeted, but the main subject matter to be claimed in the present specification may be applied to other communication systems and services having a similar technical background as well. It can be applied within a range that does not significantly deviate from the scope, and this will be possible at the discretion of a person with technical knowledge skilled in the art.
It should be noted that the above embodiments and the features of the embodiments of the present application can be combined without conflicts occurring. Hereinafter, the present application will be described in detail with reference to the accompanying drawings related to the above embodiments.
In the following description, a base station (BS) is an access device through which communication apparatuses access a cellular network, and is used to allocate communication resources to the communication apparatuses. The base station may be any one of the following physical devices: an enhanced Node B (eNB), a Node B, a radio electric access unit, a base station controller, a base transceiver terminal, etc. can The communication devices may be devices intended to access a service via an access network and may be configured to communicate via the access network. As an example, the communication devices may include a user terminal (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system that provides a communication function, but not limited thereto. It is not limited. It should be noted that in the following description, the terms "communication apparatus", "user equipment" and "user terminal" may be used interchangeably.
Although each embodiment is described herein in a cell network of LTE/LTE-A type for illustration purposes, those skilled in the art should note that the disclosed embodiments may be applied to other types of cellular networks as well. something to do. Those skilled in the art should understand that although measuring and reporting CSI in the unlicensed bands will be mainly described below, the proposed technical solutions may also be applied to measuring and reporting CSI in the licensed bands. something to do. For example, for some reason (eg, discontinuous transmission), there may be a situation in which no signal is transmitted in the licensed bands, which is a long period of time. The technical solution provided by each embodiment can be applied to this situation.
In order to use the channel resource of the carrier in the unlicensed band, the UE needs to report the CSI as accurately as possible. An embodiment of the present application provides a method for handling CSI reports.
In the unlicensed band, the LTE device must determine whether it is possible to occupy the channel according to the CCA result. Therefore, the time during which the LTE device can occupy the channel is not determined, and the LTE device cannot transmit any signal for a long time. As a result, the base station cannot periodically transmit a reference signal for CSI measurement, and the CSI measurement in the UE may also be affected. In order to ensure the efficiency of measuring and reporting the CSI, it is necessary to obtain as many opportunities as possible for transmitting a reference signal for CSI measurement. The reference signal for CSI measurement as described above may be a cell common reference signal (CRS), a channel state information reference signal (CSI-RS), or a newly defined reference signal structure. have.
2 is a diagram illustrating a preferred flowchart of a method for measuring and reporting the CSI according to an embodiment of the present application.
As shown in FIG. 2 , the method includes step 201 in which the UE measures the CSI in multiple types of downlink signals.
There may be multiple types of signals transmitted by the base station, which may be used for the CSI measurement.
The first type is a type in which a base station occupies a channel to transmit a downlink data signal, and transmits a reference signal for CSI measurement while transmitting data. In this case, on one side, the UE may receive a reference signal from the base station and perform the CSI measurement for the channel. On the other side, the interference of other devices to the UE reflects the interference received by the UE relatively accurately when receiving data. Therefore, the CSI measurement has higher validity.
The second type is a type in which the base station transmits a discovery reference signal (DRS). The function of the DRS includes providing a criterion measured by Radio Resource Management (RRM) of the UE. That is, even when the base station does not transmit data, the DRS must be transmitted at an arbitrary density. Here, in LTE version 12, the DRS is transmitted at an arbitrary period and duration, which can be generally 1 to 5 frames. However, in the unlicensed band, the timing of transmitting the DRS cannot be periodic due to the influence of the CCA, and the DRS cannot be transmitted in time when the channel is always busy. To support the CSI measurement, the DRS may be considered as a reference signal for measuring the CSI in one implementation. Alternatively, the reference signal for the CSI measurement may be transmitted in the channel occupancy time of the DRS.
The third type is a type in which the base station occupies a channel and transmits only a specific reference signal for the CSI measurement. By using this method, the reference signal for the CSI measurement can be transmitted at a faster frequency than the frequency at which the DRS can be transmitted.
For the second type and third type of downlink signals, if the base station does not transmit signals on all subcarriers within the system bandwidth, generally the second type and third type of downlink signals The transmit power will be lower than the signal power of the downlink signal of the first type. As a result, devices outside a small range of the base station's attention may begin to initiate signals due to detection of the low interference level. That is, the level of interference that the UE receives from other devices is higher than the level of the first type of interference. Thus, the CSI measurements based on the second type and third type downlink signals (referred to briefly as the second type CSI measurement and the third type CSI measurement, respectively) are intrinsically Measurements under circumstances where the base station does not transmit downlink data and is not very important. In the description of the following embodiments of the present application, the second type of CSI measurement and the third type of CSI measurement may be combined and, for example, may be considered to have the same priority. Alternatively, these two types of CSI measurements can be further distinguished. As an example, different priorities may be assigned to these two types. For convenience of explanation, these two types of measurements are considered as one type in the following description. It should be understood by those skilled in the art that the method can be easily extended to the situation of distinguishing these two types of CSI measurements.
In practice, the base station can sometimes transmit multiple types of signals after occupying a channel. For example, the base station transmits downlink data and simultaneously transmits DRS. Alternatively, the base station also transmits a reference signal specific to the CSI measurement when transmitting the DRS. At this time, these types of signals may also be classified according to the level of interference with the UE. As an example, for the case where the base station transmits downlink data and transmits DRS at the same time, interference with the UE of other devices reflects the interference received by the UE relatively accurately when receiving data. In this way, at this time, the CSI measurement and the CSI measurement based on the downlink signal of the first type (referred to as the CSI measurement of the first type for short) can be considered as one type.
Alternatively or additionally, when it is impossible for the base station to transmit data signals by occupying a channel for a long time, and it is impossible for the base station to occupy a channel to transmit a specific reference signal for DRS or CSI measurement, that is, when the UE occupies a long time If a signal transmitted by the base station is not received during the period, the CSI measured a long time ago by the UE may no longer reflect the channel state at the time when the UE reports the CSI. Accordingly, such information is invalid information. In this case, the UE may transmit CQI index 0 (OOR) to indicate an invalid CQI. Alternatively, the opportunity to report the CSI can also be used to report the current level of channel interference to provide some basis for the scheduling of the base station. Because the base station has failed to occupy the channel and transmit downlink signals, there may be other devices close to the base station, so the level of interference received by the UE may be relatively high, and the base station may It can be higher than the situation of transmitting types of signals.
Here, in some embodiments, a window of the CSI measurement may be configured. That is, if both the downlink data and the reference signal specific to the DRS and the CSI measurement are not transmitted by the base station in this window, the UE reports only a pure indicator of the interference level. Alternatively, the UE preferentially feeds back CSI information measured during downlink data transmission of the base station or CSI information based on the DRS or a reference signal specific to the CSI measurement.
In one implementation, this window may be determined with respect to subframe n in which the CSI transmission is present, that is, [nW , nk ], where W-k+1 is the number of subframes included in this window and , k is based on the process delay of the UE, for example, k =4.
Contrary to this, in another implementation, for aperiodic CSI, this window also triggers aperiodic CSI (aperiodically CSI: A-CSI) in subframe m of an uplink grant (UL grant) , that is, [ mX , mx ], where X - x + 1 is the number of subframes included in this window, and x is based on the UE's process delay. When x > 0, the UE can use more time for processing, when x < 0, the CSI can be fed back more timely. Alternatively, x may be 0.
Referring back to FIG. 2 , in step 202, the UE feeds back measured CSI based on multiple types of downlink signals.
According to the above analysis, the accuracy and efficiency of the CSI measured based on the plurality of types of signals are different. Accordingly, the present application provides a method for processing CSI feedback.
Four preferred embodiments provided by the present application for processing CSI feedback are described below.
first embodiment
In the first embodiment, how to perform CSI measurement based on the DRS transmitted by the base station is described.
In the carrier in the unlicensed band, the base station determines whether the channel can be occupied according to the CCA result. After the channel is occupied by the base station for a period of time, the base station must release the channel according to European regulations, in which the time to occupy the channel must not exceed 13 ms. In this way, the base station may not be able to occupy the channel for a long time, and if it does occupy the channel, it may only last for a short time. Although the CSI measurement measured at the time when the base station transmits downlink data is most accurate, when the base station transmits downlink data, the measurement and reporting of the CSI by the UE is generally at the current channel occupancy time. It cannot be used to schedule downlink data. If the next time the base station occupies the channel and transmits data occurs after a long time, this CSI information may expire. In addition, in order to acquire CSI information in a timely manner when the base station occupies the channel and transmits downlink data, it is necessary for the base station to acquire relatively new CSI before transmitting the data. The base station can solve the above problem by integrating a reference signal for CSI measurement or by transmitting a reference signal specific for CSI measurement when transmitting DRS. The reference signal for the CSI measurement may be a CRS, CRS-RS, or a newly defined reference signal structure.
Restrictions on transmitting specific reference signals for the DRS and CSI measurements are relatively loose. For example, when the reference signal specific to the DRS and the CSI measurement is processed as a Short Control Signal (SCS) according to European regulations, the base station cannot generate the CCA, but periodic generation of these signals These signals can be transmitted directly to ensure that the CSI measurement can be adapted. Alternatively, although the base station still needs CCA before transmitting these signals, the condition is much looser than the situation of transmitting the downlink data. As an example, the threshold of CCA detection is relatively high, so the probability that the base station can transmit these signals is higher than the probability of transmitting downlink data, thus helping to provide more opportunities for measuring the CSI becomes this Also, although the transmission conditions and the reference signal specific to the DRS and the CSI measurement are the same as the conditions for transmitting the downlink data, the use of these signals may also be beneficial. For example, in a situation of a relatively low load, the base station does not currently have data, so the base station transmits only a reference signal specific for DRS and/or CSI measurement to provide an opportunity to acquire the CSI in a timely manner can do. A processing method for performing CSI measurement based on the DRS transmitted by the base station according to some preferred embodiments will be described below.
The first method is to use the DRS transmitted by the base station as a reference signal for the CSI measurement.
3 shows a schematic diagram of the structure of a DRS.
As shown in Figure 3, according to the definition in Standard Release 12 (Release 12: Rel-12), the DRS is a plurality of types of signals, that is, a Primary Simultaneous Signal (PSS), an Auxiliary Simultaneous Signal Includes a Secondary Simultaneous Signal (SSS) and CRS port 0. The base station may configure the DRS to include one NZP CSI-RS port. In this way, the UE can measure the CSI using the CRS port 0 and/or this NZP CSI-RS port. In particular, both types of signals may be used for the CSI measurement. Alternatively, only one type of signal is used to measure the CSI. Alternatively, the CSI may also be measured according to a transmission mode (TM) of the UE. For example, for TM 1 to TM 8, CSI may be measured based on the CRS port 0. For TM 9, the channel portion of the CSI may be measured based on this NZP CSI-RS port, and the interference portion of the CSI may be measured based on the CSI port 0 . For TM 10, the channel component of the CSI may be measured based on this NZP CSI-RS port, and the interference component of the CSI is a resource element in which the current cell power is 0 in DRS sub-frames (Recourse Element: RE) can be measured based on For example, the RE in which the current cell power is 0 may mean all REs in which the current cell power is 0 in the DRS subframes. Alternatively, the RE may be an interference measurement resource configured by higher layer signaling in one of the subframes occupied by the DRS, for example, by reusing the configuration method of the ZP CSI-RS. Alternatively, preferably, the subframe in which the ZP CSI-RS exists may be a subframe including the NZP CSI-RS among subframes occupied by the DRS.
The second method is to extend the structure of the DRS defined by Rel-12 to include more reference signal ports for CSI measurement. That is, the UE measures CSI using the reference signal ports of the extended DRS.
In one aspect, in order to support CSI measurement based on the plurality of CRS ports, the DRS may be extended to include a plurality of CRS ports. In some embodiments, the extension of the CSR port may be performed in all of the subframes occupied by the DRS.
In one implementation, the extended CRS port(s) may directly reuse the mapping structure of the existing CRS ports 1 to 3 in the subframe.
4 shows a schematic diagram of a preferred structure in which the DRS is expanded to include a plurality of CRS ports.
As shown in FIG. 4 , if it is assumed that two CRS ports are required, CRS port 0 and CRS port 1 may be transmitted in the DRS.
Alternatively, in another implementation, the extended CRS port(s) may also be obtained by shifting the existing CRS port in the time domain.
5 shows a schematic diagram of another preferred structure for extending the DRS to include a plurality of CRS ports.
As shown in FIG. 5, if it is assumed that two CRS ports are required, the CRS port 0 is shifted to the right by one Orthogonal Frequency Division Multiplexing (OFDM) symbol to obtain a new port. The new port is different from each of the four existing CRS ports and is recorded as CRS port x, and is used to measure the channel of the CRS port 1. The use of this method may be beneficial for distributing multiple CRS ports of different OFDM symbols, so that when multiple CRS ports are transmitted, the transmit power is not increased, or the transmit power is increased as little as possible.
4 and 5, it is assumed that the extension of the CRS port can be performed in all of the subframes occupied by the DRS. Alternatively, in other embodiments, only some of the subframes occupied by the DRS are extended to include multiple CRS ports. For example, the extension of the CRS port is performed only in one of the subframes occupied by the DRS. These subframes extended to include CRS ports may be configured semi-statically or statically by the higher layer signaling. For example, the subframe including the PSS/SSS performs CRS extension.
6 shows a schematic diagram of another preferred structure in which the DRS is extended to include a plurality of CRS ports.
As shown in FIG. 6 , the extended CRS port can directly reuse the mapping structure of the existing CRS ports 1 to 3 in the subframe, and occupy only the second subframe occupied by the DRS. It is assumed that there can be
7 shows a schematic diagram of another preferred structure in which the DRS is extended to include a plurality of CRS ports.
As shown in FIG. 7 , it is assumed that the extended CRS port can also be obtained by shifting the existing CRS port in the time domain, and can occupy only the second subframe occupied by the DRS. In FIG. 7 , it is assumed that four CRS ports are required, where CRS ports a/b/c are obtained by shifting the existing CRS ports, and correspond to measurements of each of the CRS ports 1/2/3.
In another aspect, in order to support the CSI-RS measurement based on a plurality of CRS ports, the DRS may be extended to include a plurality of CRI-RS ports. Here, the number of CSI-RS ports included by the DRS after the extension is the same as the number of CSI-RS ports for the CSI measurement. In particular, when two CSI-RS ports are required, CSI-RS port 15 and CSI-RS port 16 may be directly supported in two mapped REs of CSI-RS configured by the DRS signal. Contrary to this, when four or eight CSI-RS ports are required, four or eight REs are allocated in a subframe in which CSI-RS configured by the DRS signal exists, and the four or eight REs, respectively Used to deliver CSI-RS resources of CSI-RS ports. The plurality of extended CSI-RS ports may also exist in one subframe of the DRS. Alternatively, the plurality of extended CSI-RS ports may be distributed in some or all of the subframes of the DRS.
Alternatively, in order to support the CSI measurement based on a plurality of CSI-RS ports, a plurality of CSI-RS ports for the CSI measurement may be configured separately. In a subframe of the DRS configured as the reference signal for the CSI measurement, both the DRS and the configured reference signal for the CSI measurement are transmitted. Here, the higher layer signaling may be used to configure the number of ports of CSI-RS resources for CSI measurement, an offset of subframes occupied by the DRS, and the occupied RE. In addition, the RE of the plurality of CSI-RS ports configured by the signal may be limited to be different from the RE of the CSI-RS ports configured by the existing DRS signal. Otherwise, no restrictions can be placed on the RE, and no restrictions can be placed on the base station implementation.
The second method of extending the structure of the DRS may extend only the CRS port, or extend only the CSI-RS port, or extend the reference signal for both types of CSI measurement. . In this way, the UE measures the CSI using the extended CRS ports and/or the extended NZP CSI-RS ports. In particular, both types of signals can be used to measure the CSI. Alternatively, only one type of signal is used to measure the CSI. Alternatively, the CSI may be measured according to a transmission mode (TM) of the UE. For example, for TM 1 to TM 8, CSI may be measured based on the CRS port. For TM 9, the channel component of the CSI may be measured based on this NZP CSI-RS port, and the interference component of the CSI may be measured based on the extended CSI port. For TM 10, the channel component of the CSI may be measured based on this NZP CSI-RS port, and the interference component of the CSI may be measured based on the RE where the current cell power is 0 in DRS sub-frames. can For example, the RE in which the current cell power is 0 may mean all REs in which the current cell power is 0 in the DRS subframes. Alternatively, the RE may be an interference measurement resource configured by reusing a configuration method of ZP CSI-RS, for example, by higher layer signaling in one of the subframes occupied by the DRS. Alternatively, preferably, the subframe in which the ZP CSI-RS exists may be a subframe including the NZP CSI-RS among subframes occupied by the DRS.
A third method is to semi-statically configure the position of the reference signal for the CSI measurement using the higher layer signaling. When the subframe in which the reference signal exists overlaps the subframe of the DRS, both the reference signal for the DRS and the CRS measurement are transmitted in this subframe of the DRS. For the CSI-RS, if the CSI-RS overlaps a subframe of the DRS, the CSI-RS may be transmitted directly in this subframe of the DRS. With respect to the CRS, the CRS may be transmitted discontinuously when used for CSI measurement. In particular, the higher layer signaling may be used to configure the cycle, offset, and period of the CRS for the CSI measurement. That is, in one cycle, the CRS for the CSI measurement is transmitted from the indicated offset. In the time period of the CRS, the CRS may be transmitted in one or more subframes. Alternatively, the CRS may be stipulated to be transmitted in a shorter period, for example, a time slot. In this way, when the CRS for CSI measurement overlaps one or more subframes of the DRS, and the CRS includes a plurality of CRS ports, the CRS having the plurality of ports is one of the DRS or It can be transmitted directly in more subframes.
second embodiment
In the second embodiment, when measuring CSI based on different types of downlink signals, how to provide feedback based on different characteristics of the CSI is described.
According to the above description of the present application, in the carrier of the unlicensed band, the CSI reported by the UE may be derived from several different types of signals. In one aspect, the CSI measurement at the time the base station transmits downlink data is the most accurate. In another aspect, the interference of other devices received by the UE reflects the interference received by the UE relatively accurately when the UE receives data. Here, since the transmit power for transmitting downlink data is generally large, all other devices within a large range close to the base station cannot transmit signals, and thus the interference received by the UE is relatively low.
8 shows a schematic diagram of interference dispersion of the UE when the base station transmits downlink signals in different areas.
As shown by reference numeral 802 in FIG. 8 , when the base station 800 transmits downlink signals, all other base stations A, B, and C around the base station 800 cannot transmit signals and , therefore, the UE receives interference only from the base station D. However, for CSI measured when the base station transmits a reference signal specific to DRS or CSI measurement, even if the channel component of the CSI measurement is still accurate, since the transmit power of the base station is generally low, Only devices within a small range cannot transmit signals, so the level of interference present from other devices and received by the UE is higher than the level of interference at the time the base station transmits downlink data. As shown at 801 in FIG. 8 , when the base station 800 transmits DRS, only the base station around the base station 800 cannot transmit signals, so the UE can transmit signals to the base stations B, C and /or may receive interference from D. In this way, when configuring the CSI feedback of the UE, different characteristics of CSI measured based on different types of signals need to be considered.
The first method is to configure CSI that feeds back only one type of signal for one CSI process. That is, one CSI process feeds back only CSI measured at a time when the base station occupies a channel and transmits downlink data, or one CSI process is measured based on the DRS or a reference signal specific to the CSI measurement Only CSI is fed back. Here, for the above method of configuring the window of the CSI measurement, the UE feeds back valid CSI only when the signal of the type corresponding to this CSI process exists in this window. Otherwise, the UE may indicate that the CSI is not valid. As an example, the UE reports CQI index 0 (OOR).
Contrary to this, the second method is to allow one CSI process to measure and feed back CSI information based on the two types of signals as described above. It will be understood here that the two types of signals are classified according to the level of interference with the UE. Here, in general, since interference levels in subframes in which the two types of signals are present are different, the averaging operation is inappropriate for interference in subframes in which the two types of signals are present. In this case, it may be defined that the measurement of the interference component of the CSI measurement can be averaged only for subframes of signals of the same type. Alternatively, it may be defined that the interference component of the CSI measurement can be calculated based on only one subframe, that is, that the averaging operation is not performed for the interference. Alternatively, it may be defined that the interference component of the CSI measurement is a weighted average based on the two types of subframes as described above.
According to the above analysis, the CSI measured based on the DRS or a reference signal specific to the CSI measurement is substantially relatively small. This is because the level of interfering signals received by the UE is very low when the downlink data is actually transmitted. In this way, the CSI measured based on the reference signal specific to the DRS or the CSI measurement can be compensated to approximate the CSI measured at the time the downlink data is transmitted.
In some implementations, the compensation may be performed at the UE side. That is, the UE determines an interference level A in a period in which the base station transmits downlink data, and determines an interference level B in a period in which the base station transmits a reference signal specific to the DRS or CSI measurement, and then , the UE may compensate the measured signal-to-noise ratio according to the interference level A and the interference level B. For example, it is assumed that the signal-to-noise ratio measured based on the reference signal specific to the DRS or the CSI measurement is increased by (BA) dB, where the units of A and B are dB.
In another implementation, the compensation may be performed at the base station side. In particular, the base station may configure CSI measurement based on downlink data transmission and signal transmission assumptions of CSI measurement based on a reference signal specific to the CSI measurement. Alternatively, when measuring the CSI based on the DRS or a reference signal specific to the CSI measurement, it may be directly instructed to increase the measured power of the channel component by X dB. Alternatively, equivalently, the measured power of the interference component may be reduced by X dB. Here, the value of X is based on the difference between the interference levels in two situations. For different UEs, X is generally different in other areas. The base station may configure the value of X through signaling.
According to the current LTE standard, for the channel measurement based on the CRS, the UE determines an assumption of signal power while measuring the CSI based on _{the power reference P A} and the offset Δ _{offset configured by the higher level.} do. That is, for a situation in which TM 2 consisting of four CRS ports, TM 3 consisting of four CRS ports, and a rank indicator (RI) is 1, ρ _A = P _A + Δ _offset + 10log ₁₀ (2) dB; Otherwise, for any modulation scheme and any number of layers, ρ _A = P _A + Δ _offset dB.
ρ _A is the ratio of the EPRE of the PDSCH in OFDM symbols that do not include the power of each RE (EPRE) of the CRS to the CRS.
In this manner, in one implementation, is to the method of compensation is made for two Δ _offset, the one of the two Δ _offset is used for the CSI measurement that is based on the downlink data transmission, Δ _offset, expressed as ₁ and the other one is used for CSI measurement based on the DRS or a reference signal specific to the CSI measurement, and is expressed as _{Δ offset, 2.} Δ _offset,2 is X dB higher than _{Δ offset,1.}
Alternatively, in another implementation, the method for the compensation is to indicate X. That is, with respect to the CSI measurement that is based on the downlink data transmission, the home of the signal power during the CSI measurement is determined based on the P _A and Δ _offset, ρ _A = f represented as (P _A, Δ _offset) lose For the CSI measurement based on the DRS or a reference signal specific to the CSI measurement, the assumption of signal power during the CSI measurement is determined as ρ _A = f(P _A , Δ _offset )+X.
According to the current LTE standard, for channel measurement which is based on the CSI-RS, and the UE determines the assumption of a signal power for the CSI measurement that is based on the power reference P _C constituted by the high-level.
In this way, in one embodiment, the method of compensation is to configure two P _C, wherein one of the two P _C is used for the CSI measurement that is based on the downlink data transmission, expressed as P _C1, The other one is used for CSI measurement based on the DRS or a reference signal specific to the CSI measurement, and is expressed as _{P C2.} P _C2 is X dB higher than _{P C1.}
Alternatively, in another implementation, the method for the compensation is to indicate X. That is, with respect to the CSI measurement that is based on the downlink data transmission, the home of the signal power during the CSI measurement is determined based on P _C. For CSI measurement based on the DRS or a reference signal specific to the CSI measurement, the assumption of signal power during CSI measurement is determined based on _{P C +X.}
third embodiment
In the third embodiment, how to report CSI when there is a collision between CSI feedback resources is described.
In some situations, the same resource may be occupied for feeding back several CSIs. As an example, in this area, periodic CSI (P-CSI) of multiple carrier components (CCs) and/or P-CSI of multiple CSI processes, and/or other sets of subframes P-CSI may be configured in the same Physical Uplink Control Channel (PUCCH) resource.In the current LTE system, for CSI feedback in the PUCCH, when there is a collision between PUCCH resources, high The order of priorities from priority to low priority is CSI report type > CSI process ID > cell ID > CSI subframe set index, where the CSI report type is a pre-coded matrix indicator/channel quality indicator ( It is used to distinguish more important CSI such as RI from normal CSI such as Pre-coded Matrix Indication/Channel Quality Indication: PMI/CQI) information.
According to the above description of the present application, in the carrier of the unlicensed band, the CSI reported by the UE may be derived from several different types of signals, and the validity of the different types of signals is different from each other. In particular, the CSI measured at the time when the base station transmits downlink data is the most accurate and therefore the most efficient. This is because the interference of other devices received by the UE reflects the interference received by the UE relatively accurately when the UE receives data. CSI measured at a time when the base station transmits the DRS or a reference signal specific to the CSI measurement has a relatively low accuracy, and thus has a relatively low efficiency. This is because the transmit power is generally relatively low, and even if the measurement in the channel component is accurate, only devices within a small range around the base station cannot transmit signals and thus the level of interference the UE receives from other devices. is higher than the level of interference at the time when the base station transmits downlink data. In conclusion, since the base station does not occupy the channel for a long time, the pure interference level indicator reported by the UE only provides a criterion for scheduling of the base station, and thus has the lowest efficiency.
In this way, in one implementation, when it occurs to feed back more CSI information of the unlicensed band by occupying the same resource, the efficiency corresponding to such multiple types of CSI measurements is the most efficient processing of the CSI report. It can be used as a high priority, ie, CSI validity > CSI report type > CSI process ID > cell ID > CSI subframe set index. In this way, the CSI measurement at the time when the base station transmits downlink data has the highest priority, and when the base station transmits the DRS or a reference signal specific to the CSI measurement, the measured CSI has an intermediate priority , the pure interference level indicator reported by the UE has the lowest priority. The pure interference level indicator may be considered as a definition not suitable for the CSI report type. Alternatively, the pure interference level indicator may be considered to correspond to one CSI report type, and may be considered to be equivalent to, for example, PMI/CQI. In this way, it can be guaranteed that the CSI reported by the UE should be the CSI with the highest validity.
Contrary to this, in another implementation, the priority of validity as described above may be set to be lower than the CSI report type, but may be set to be higher than other parameters, for example, CSI report type > CSI validity > CSI process ID > Cell ID > CSI subframe set index. In this way, it is guaranteed that the priority of more important CSI information, such as RI, is higher than normal PMI/CQI information. The pure interference level indicator may be considered as a definition not suitable for the CSI report type. Alternatively, the pure interference level indicator may be considered to correspond to one CSI report type, and may be considered to be equivalent to, for example, PMI/CQI.
In addition, when the case of feeding back the CSI of the carrier of the unlicensed band and the CSI of the licensed band by occupying the same resource occurs, the order of priorities of the CSI of the licensed band and the plurality of types of CSI of the unlicensed band need to define
In one implementation, when the priority is determined, the band types may be classified, ie, classified into a licensed band and an unlicensed band. The band type may have the highest priority; or the priority of the type of the band is higher than the priority of the CSI validity but lower than the priority of the CSI report type; or the priority of the band type is higher than the priority of the CSI report type, but lower than the priority of the CSI validity; or the priority of the band type is lower than the priority of the CSI validity, but higher than the priority of other parameters; or the priority of the band type is higher than the priority of the cell ID but lower than the priority of the CSI process ID; Alternatively, the priority of the band type is higher than the priority of the CSI subframe set index, but lower than the priority of the cell ID.
Alternatively, in another implementation, the validity of the CSI of the licensed band may be specified such that it can be ordered according to the validity together with the validity of the CSI of the unlicensed band. Here, the reference signal for the CSI measurement of the licensed band may be transmitted periodically, and the CSI may always be reported in time. Accordingly, the validity of the CSI of the licensed band may be defined to be higher than that of the CSI of the unlicensed band. On the other hand, when the contention characteristics of channel occupation of the unlicensed band are considered, the opportunity for measuring CSI based on the downlink data transmission and/or the DRS or a reference signal specific for the CSI measurement is limited. Accordingly, the validity of the CSI of the licensed band may be defined to be lower than the validity of the CSI measured based on a specific reference signal for the downlink data transmission and/or the DRS or the CSI measurement. Contrary to this, the validity of the CSI of the licensed band is lower than the validity of the CSI measured based on the downlink data transmission, but is defined to be higher than the validity of the CSI measured based on the DRS or a reference signal specific to the CSI measurement. can be
For P-CSI, the PUCCH resource of P-CSI of a plurality of licensed band cells and unlicensed band cell may be configured entirely in the same or partially identical subframes, and then in the subframe, the UE selects which CSI Whether to feed back is determined using the prioritization classification as described above. For example, the priority of the CSI of the unlicensed band is configured to be higher than that of the CSI of the licensed band, and the UE is based on the downlink data, the DRS, or a reference signal specific to the CSI measurement. The window reporting the n is configured to be a small value. That is, the UE may only report the CSI based on the downlink data, the DRS, or a reference signal specific to the CSI measurement within a small period from the base station occupying the channel. The UE preferentially reports the CSI because the priority of the CSI is higher than that of the CSI of the licensed band. However, at a timing position of another feedback P-CSI, the unlicensed band can only feed back a pure interference indicator. According to the above priority, the UE feeds back the P-CSI of the licensed band. In this way, feedback of different types of CSI of different bands in one PUCCH resource according to importance is achieved, and thus the resource utilization rate is improved.
9 shows a preferred schematic diagram for feeding back P-CSI based on priority.
As shown in FIG. 9 , for the P-CSI feedback in uplink subframe n, only downlink signals in subframe n-4 and subframe n-5 measure the CSI without losing generality, as shown in FIG. can be used for, ie, the size of the window is 2. The priority of the CSI measured by the UE based on the DRS transmission 901 is higher than that of the CSI of the licensed band, and thus, the UE feeds back the CSI of the unlicensed band in the PUCCH resource 911. Similarly, the UE measures the CSI based on the downlink data transmission 902 and the DRS 903 , and feeds back the CSI of the unlicensed band in the PUCCH resource 914 and the PUCCH resource 915 . However, in other PUCCH resources, since only the pure interference indicator priority can be fed back in the unlicensed band lower than the priority of the CSI of the licensed band, the UE uses the PUCCH resources 910, 912, 913, 916, 917) feeds back the CSI of the licensed band. In this way, the UE may report the CSI of the unlicensed band as long as the most recent good information in the unlicensed band exists, and may report the CSI of the licensed band at different times.
Similarly, the above method of processing the P-CSI may be extended to aperiodical CSI (A-CSI). When the A-CSI is configured by higher layer signaling, a plurality of licensed band cells, unlicensed band cells, and/or CSI process may be divided into groups requiring only one CSI to be fed back. The UE may still select the CSI information that needs to be fed back using the priority strategy as described above.
For the above method of feeding back the P-CSI and A-CSI, the finally selected CSI information is based on the validity of the CSI measured in the unlicensed band, that is, the base station in the unlicensed band It is based on whether or not downlink data has been transmitted. However, the event in which the base station occupies the channel and transmits the downlink data is obtained using blind detection of the UE or a Downlink Control Indication (DCI) in the licensed band, for example, common It is indicated by the DCI format in the Common Search Space (CSS). These methods are not very reliable, which may cause the base station and the UE to differently understand whether there is CSI measured based on the downlink data transmission. In order to prevent collision of the UE when reporting the CSI, in some embodiments, the indicator information of the CSI may be transmitted in the CSI report reporting the CSI. For example, the UE may report the cell ID, CSI process ID, CSI validity type corresponding to the fed back CSI, and the like.
fourth embodiment
In the fourth embodiment, how to adjust the CSI feedback according to the change of the signal type for the CSI measurement is described.
According to the current LTE standard, CSI information of up to 11 bits may be fed back from the PUCCH every time. In this way, for subband CSI, the UE cannot feed back CSI information of each subband in the full bandwidth at a time, but divide the entire bandwidth into several bandwidth parts (Bandwidth Part: BP) and , therefore, only the subband PMI/COI of one CP can be fed back at a time. In addition, the cycle through which the UE feeds back the RI is relatively long. That is, in one cycle of feeding back the RI, there may be several opportunities for feeding back the PMI/CQI of the BP.
According to the above description of the present application, in the carrier of the unlicensed band, the CSI reported by the UE may be derived from several different types of signals. In particular, the CSI measured at the time when the base station transmits downlink data is the most accurate. CSI measured at a time when the base station transmits the DRS or a reference signal specific for the CSI measurement has a relatively low accuracy. Since the base station does not occupy the channel for a long time, the pure interference level indicator reported by the UE has the lowest validity. Due to the randomness in which the base station occupies the channel, the time of occurrence of the several possible types of signals is not determined. In particular, after the RI is reported based on one type of signal, before the PMI/CQI reporting of all BPs is completed, a new type of signal may be generated. Therefore, it is necessary to define how the UE processes CSI measurement and feedback under such circumstances.
10 is a diagram illustrating situations that may occur when CSI is fed back due to CSI measured based on different types of signals.
As shown in FIG. 10, it is assumed that the system bandwidth is divided into 5 BPs. Downlink data transmission ( 1002) may operate as a reference of CSI measurement for processing the CSI report of the two BPs 1015 and 1016. However, the characteristics of the DRS 1001 and the downlink data transmission 1002 are different.
In the first method, it does not matter which new signal type is useful for measuring CSI, the PMI/CQI reporting of all BPs in the full bandwidth is always according to the most recently reported signal type of the RI, and the same type of signal is completed based on However, a new RI report needs to be measured according to a new signal type.
11 shows a preferred schematic diagram of CSI feeding back RI and CSI feeding back each BP according to the first method.
As shown in FIG. 11 , the fed back RI 1111 is obtained according to the DRS 1101 and then five BPs 1112 to 1116 , and each of the five BPs 1112 to 1116 is a DRS That is, it is measured based on the DRS 1101 in FIG. 11 . Next, the fed back RI 1117 is obtained according to the downlink data transmission 1102 and then five BPs 1118 to 1122, each of which is a downlink data transmission. , that is, measured based on the downlink data transmission 1102 in FIG. 11 .
In the second method, due to the occurrence of a new signal type useful for measuring CSI, the PMI/CQI and RI of the next BP are measured based on the new signal type. Here, before reporting the new RI, even if the PMI/CQI of the BP is measured based on the new signal type, it is assumed that the RI is the same as the most recently reported RI.
12 is a diagram illustrating a preferred schematic diagram of CSI feeding back RI and each BP according to the second method.
12, after the fed back RI 1211 and subband CSIs 1212 to 1214 of three BPs are obtained according to the DRS 1201, the downlink data transmission 1202 is CSI It becomes possible to act as a reference for measurement. At this time, although the UE still operates according to the RI fed back in 1211 , the subband CSI of the two BPs 1215 and 1216 is calculated based on the downlink data transmission 1202 . Next, the UE may acquire the subband CSI 1218 of the RI 1217 and the BP based on the downlink data transmission 1202 . Then, for the next four BPs 1219 to 1222 , the RI calculated according to the downlink data transmission 1202 is used, but the subband CSI is calculated based on the DRS 1203 .
In the third method, when the priority of the new signal type useful for measuring CSI is higher than the priority of the previous signal type, the PMI/CQI and RI of the next BP are measured based on the new signal type. Here, before reporting the new RI, even though the PMI/CQI of the BP is being measured based on the new signal type, it is assumed that the RI is the same as the most recently reported RI. If the priority of a new signal type useful for measuring CSI is lower than that of the previous signal type, the old signal type is still used to feed back the CSI.
13 shows a preferred schematic diagram of each BP and CSI feedback RI according to the third method.
As shown in FIG. 13 , after the fed back RI 1311 and subband CSIs 1312 to 1314 of three BPs are obtained according to the DRS 1301 , the downlink data transmission 1302 performs CSI measurement. It can act as a standard for At this time, since the priority of the CSI based on the downlink data transmission 1302 is higher than that of the CSI based on the DRS 1301, the two BPs 1315 and 1316 are fed back The processing method is the same as the second method. That is, the UE still operates according to the fed back RI at 1311 , but the subband CSI of the two BPs 1315 and 1316 is calculated based on the downlink data transmission 1302 . In the following, the UE may acquire the subband CSI 1318 of the RI 1317 and the BP based on the downlink data transmission 1302 . Then, for the next four BPs 1319 to 1322, the priority of the CSI based on the DRS 1303 is lower than that of the CSI based on the downlink data transmission 1302, In the third method, the subband CSI is still calculated based on the downlink data transmission 1302 .
In the fourth method, when the priority of the new signal type useful for measuring CSI is higher than the priority of the previous signal type, from a PUCCH resource that satisfies a process delay, RI measured based on the new signal type is reported first, and then the PMI/CQI of each BP is reported. When this method is used, the time for reporting the RI is random. Accordingly, when P-CSI is fed back from the PUCCH, it is necessary to indicate the CSI type currently reported by the UE, that is, the RI related information or the PMI/CQI of the BP.
14 is a diagram illustrating a preferred flowchart of a method for receiving CSI according to an embodiment of the present invention. As shown in FIG. 14 , the method includes the step 1401 of the base station transmitting multiple types of downlink signals for CSI measurement.
The signals transmitted by the base station and useful for CSI measurement include: a reference signal for CSI measurement transmitted within a time period during which the base station transmits downlink data; DRS; There may be other types including at least one of the reference signals specific to CSI measurement. Since the specific details have been described above, the specific details will be omitted.
In step 1402, the base station receives the CSI measured based on the plurality of types of downlink signals and fed back by the user equipment (UE).
In some embodiments, receiving CSI fed back by the UE and measured based on multiple types of downlink signals includes: receiving only CSI measured based on one type of downlink signal in one CSI process do or; Alternatively, it includes receiving CSI measured based on a plurality of types of downlink signals in one CSI process.
When receiving CSI measured based on multiple types of downlink signals in one CSI process, the base station may perform the following operations: Accordingly, constructing signal power assumptions of the CSI measurement based on each of the different types of downlink signals; or instructing the UE to increase the power of the channel component obtained from the CSI measurement corresponding to the high interference level by a predetermined value (eg, X dB), or from the CSI measurement corresponding to the high interference level reducing the power of the interference component to be obtained by the predetermined value (X dB).
15 is a diagram illustrating a simplified block diagram of an entity 1500 that is adapted to implement many preferred embodiments of the present application. The entity 1500 may be configured as a network-side device such as a base station. The entity 1500 may also be configured as a user-side device such as a user terminal.
As shown in FIG. 15 , the entity 1500 includes a processor 1501 , a memory 1502 coupled to the processor 1501 , and a suitable radio frequency coupled to the processor 1501 . frequency: RF) transmitter and receiver 1504 . The storage unit 1502 stores a program 1503 . The transmitter/receiver 1504 is suitable for two-way wireless communication. It should be noted that the transmitter/receiver 1504 has at least one antenna to aid in communication. In practice, the base station or UE may have multiple antennas. The entity 1500 may be connected to one or more external networks or systems, such as internetworks, via a data path.
The program 1503 may include program instructions. When these program instructions are executed by the coprocessor 1501, the program instructions cause the entity 1500 to operate in accordance with preferred embodiments of the present invention.
Embodiments of the present invention may be implemented by computer software or hardware that can be executed by the processor 1501 of the entity 1500 , or a combination of the software and hardware.
The storage unit 1502 may be any type of memory suitable for a local technical environment, and may include semiconductor-based storage devices and systems, magnetic storage devices and systems, optical storage devices and systems, and fixed devices. It may be implemented using any suitable data storage techniques, such as local storage and removable storage, which are examples without limitation. Although only one memory is shown in the entity 1500 , a plurality of physically separate memory cells may exist in the entity 1500 . The processor 1501 may be any processor of a suitable type, suitable for the local technical environment, and may include one or more of the following items: a general purpose computer, a dedicated computer, It may include a processor based on the architecture of a micro-processor, a digital signal processor (DSP), or a multi-core processor, which is just non-limiting examples.
When the entity 1500 is configured as a user-side device, i.e. the entity 1500 is a user terminal, in some embodiments, the receiver of the transmitter/receiver 1504 transmits multiple types of downlink signals. configured to receive The processor 1501 is configured to measure Channel State Information (CSI) in the plurality of types of downlink signals. The transmitter of the transmitter/receiver 1504 is configured to feed back the measured CSI based on the plurality of types of downlink signals to the base station.
When the entity 1500 is configured as a network-side device, that is, when the entity 1500 is a base station, in some embodiments, the transmitter of the transmitter/receiver 1504 is under the control of the processor for CSI measurement. and transmit multiple types of downlink signals. The receiver of the transmitter/receiver 1504 is configured to receive CSI fed back by a User Equipment (UE) and fed back based on multiple types of downlink signals.
It should be understood that the units included in the entity 1500 are configured to implement the preferred embodiments described herein. Accordingly, the above operations and features described with reference to FIGS. 3 to 14 are also suitable for the entity 1500 and its units, and a detailed description thereof will be omitted herein.
In another aspect, the present application provides a computer readable storage medium, wherein the computer readable storage medium exists separately in the computer readable storage medium included in the base station or the communication device or the device of the above embodiments. It may be a non-assembled computer readable storage medium. The computer readable storage medium stores one or more programs, which are used by one or more processors to execute a cellular access method as described in the present application.
The above description is merely an example of preferred embodiments of the present application and technical principles being used. Those skilled in the art should understand that the scope of the invention related to the present application is not limited to the technical solution formed by the specific combination of the technical features as described above, and Other technical solutions formed by any combination of the same technical features or equivalent features, for example, the technical features as described above are disclosed in the present application (but not limited thereto), and similar functions It should be understood that the branch must contain the technical features and the technical solutions formed by the interchange of each other.
Various embodiments of the present invention may be embodied as computer readable code on a computer readable recording medium in certain respects. A computer readable recording medium is any data storage device capable of storing data that can be read by a computer system. Examples of computer-readable recording media include read only memory (ROM: ROM), random access memory (RAM: 'RAM), and compact disk-read only memory (compact disk-read only memory). memory: CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission over the Internet); may include The computer readable recording medium may also be distributed over network coupled computer systems, so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for achieving various embodiments of the present invention may be easily interpreted by programmers skilled in the field to which the present invention is applied.
In addition, it will be appreciated that the apparatus and method according to various embodiments of the present invention can be realized in the form of hardware, software, or a combination of hardware and software. Such software may include, for example, a volatile or non-volatile storage device, such as a ROM, or a memory, such as, for example, RAM, a memory chip, device or integrated circuit, whether erasable or rewritable, or For example, the storage medium may be stored in an optically or magnetically recordable storage medium such as a compact disk (CD), a DVD, a magnetic disk, or a magnetic tape, and a machine (eg, computer) readable storage medium. The method according to various embodiments of the present invention may be implemented by a computer or portable terminal including a control unit and a memory, and the memory is to store a program or programs including instructions for implementing the embodiments of the present invention. It will be appreciated that this is an example of a suitable machine-readable storage medium.
Accordingly, the present invention includes a program including code for implementing the apparatus or method described in the claims of the present specification, and a machine (computer, etc.) readable storage medium storing the program. Also, such a program may be transmitted electronically over any medium, such as a communication signal transmitted over a wired or wireless connection, and the present invention suitably includes the equivalent thereof.
In addition, the device according to various embodiments of the present disclosure may receive and store a program from a program providing device connected by wire or wirelessly. The program providing apparatus includes a program including instructions for causing the program processing apparatus to perform a preset content protection method, a memory for storing information necessary for the content protection method, and the like for performing wired or wireless communication with the graphic processing apparatus. It may include a communication unit and a control unit for automatically transmitting a corresponding program to the transceiver or a request from the graphic processing device.
The embodiments of the present invention disclosed in the present specification and drawings are merely provided for specific examples to easily explain the technical content of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. In addition, the above-described embodiments according to the present invention are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent ranges of embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

Claims (21)

A method for measuring and reporting channel state information (CSI), the method comprising:
a process in which a user terminal (UE) measures CSI for multiple types of downlink signals;
The UE feeds back the CSI measured based on the plurality of types of downlink signals,
The CSI is measured based on at least one type of downlink signal selected from among the plurality of types, wherein the plurality of types of downlink signals are: by the base station within a time period during which the base station transmits downlink data a reference signal for CSI measurement transmitted, a search reference signal (DRS) transmitted by the base station, and a reference signal specific to CSI measurement and transmitted by the base station;
The process of feeding back the CSI is:
When it occurs that the first CSI of the unlicensed band and the second CSI of the licensed band occupy the same resource for being fed back, at least one of the band type and validity of the first and second CSI determining priorities of the first CSI and the second CSI; and
Method for measuring and reporting CSI comprising the step of feeding back CSI having a higher priority according to the determination. The method of claim 1, further comprising: indicating to the base station that the CSI is not valid when the UE does not receive any signal transmitted by the base station within a predetermined time period; or
The method of measuring and reporting CSI further comprising the step of the UE indicating a current channel interference level to the base station. The method of claim 2, wherein the step of indicating the current channel interference level to the base station by the UE comprises:
The process of the UE feeding back a pure interference level indicator to the base station when the signal transmitted by the base station is not received within a window configured by the base station to measure the CSI A method of measuring and reporting CSI, characterized by The method of claim 3, wherein the measuring of the CSI comprises:
directly using the DRS as a reference signal for the CSI measurement;
extending the DRS for the CSI measurement and using a plurality of reference signal ports included in the DRS;
A method of measuring and reporting CSI comprising any one of the steps of performing the CSI measurement based on a reference signal for the CSI measurement configured in the DRS through high layer signaling. 5. The method of claim 4, wherein the process of using a plurality of reference signal ports included in the DRS comprises:
a process of using a plurality of CRS ports extended and included in all or some of the sub-frames of the DRS for the CSI measurement;
The method of measuring and reporting CSI, comprising at least one of using a plurality of CSI-RS ports extended and included in all or some of the subframes of the DRS for the CSI measurement. 5. The method of claim 4, wherein the higher layer signaling comprises a cycle, an offset, and a duration of a cell common reference signal for the CSI measurement. The method of claim 1, wherein the feedback of the CSI comprises:
When occupying the same resource to feed back a plurality of CSIs of an unlicensed band, it includes the process of feeding back the CSI according to a predetermined priority,
The predetermined priority is:
The validity of each CSI is determined to have the highest priority;
A method of measuring and reporting CSI, characterized in that the CSI report type has the highest priority, and the priority of validity of each CSI is determined to be lower than the priority of the CSI report type. delete The method of claim 1, wherein the second CSI of the licensed band has a predetermined validity, the predetermined validity comprising:
is determined to be higher than the first CSI of the unlicensed band;
is determined to be lower than the first CSI of the unlicensed band;
Although lower than the first CSI of the unlicensed band, the method for measuring and reporting CSI, characterized in that it is determined to be higher than the CSI measured based on a reference signal specific to the DRS and CSI measurement. The method of claim 1, wherein the feedback of the CSI comprises:
The method further comprises the step of reporting, by the UE, identification information of the fed back CSI,
The identification information comprises at least one of a corresponding cell identifier, a CSI process identifier, and a CSI validity type. The method of claim 1, wherein the feedback of the CSI comprises:
Feeding back CSI measured based on one type of downlink signal in one CSI process; or
A method of measuring and reporting CSI, comprising the step of feeding back CSI measured based on the plurality of types of downlink signals in one CSI process. The method according to claim 11, wherein when the CSI measured based on the plurality of types of downlink signals is fed back in the one CSI process, the interference component of the CSI measurement is:
obtained by performing an averaging operation on the measurement of the interference component only in subframes of signals of the same type;
obtained through measurement of the interference component without an averaging operation;
A method for measuring and reporting CSI, which is obtained by taking a weighted average of the measurement of the interference component based on interference levels corresponding to different types of downlink signals. The method according to claim 12, wherein when CSI measured based on the plurality of types of downlink signals is fed back in one CSI process, the different types of downlink signals are selected according to interference levels corresponding to the different types of downlink signals. A method of measuring and reporting CSI, comprising the step of performing a compensation operation on the CSI measured based on downlink signals. 14. The method of claim 13, wherein the compensating operation comprises:
The UE determines the interference level A in the period in which the base station transmits downlink data, the base station determines the interference level B in the period in which the base station transmits a reference signal specific for the DRS or the CSI measurement, and the UE determines the compensating for the signal-to-noise ratio obtained from the CSI measurement of the UE according to the interference level A and the interference level B;
According to the commands of the base station, the power of the channel component obtained from the CSI measurement corresponding to the predetermined interference level is increased by a predetermined value, or the CSI measurement corresponding to the predetermined interference level A method of measuring and reporting CSI comprising any one of the operations of reducing the power of the interference component obtained from the predetermined value. The method of claim 1, wherein the feedback of the CSI comprises:
Pre-coded matrix indicator and/or channel quality indicator of all bandwidth parts (BWP) based on the same type of signal according to the signal type based on the most recently reported rank indicator (Rank Indication: RI) a method of feeding back (Pre-coded Matrix Indication and/or Channel Quality Indication: PMI/CQI);
a method of feeding back the PMI/CQI of each BP based on a downlink signal of a channel most recently occupied by the base station, where it is assumed that RI is the same as the most recently reported RI;
When the priority of the new signal type useful for measuring the CSI is higher than the previous signal type, the PMI/CQI of each BP is fed back based on the downlink signal of the channel most recently occupied by the base station; where RI is assumed to be the same as the most recently reported RI;
When the priority of the new signal type useful for measuring the CSI is higher than the previous signal type, from a Physical Uplink Control Channel (PUCCH) resource that satisfies the process delay, the PMI/CQI of each BP and the Method of measuring and reporting CSI, characterized in that it further comprises the step of feeding back the RI and PMI/CQI of each BP subband according to any one of the methods of feeding back the measured RI based on the new signal type. A method for receiving channel state information (CSI), the method comprising:
a process in which a base station transmits multiple types of downlink signals for CSI measurement;
and receiving, by the base station, CSI fed back by a user terminal (UE) and measured based on the plurality of types of downlink signals,
The CSI is measured based on at least one type of downlink signals selected from among the plurality of types, and the plurality of types of downlink signals are: Transmitting within a time period in which the base station transmits downlink data A reference signal for CSI measurement, a search reference signal (DRS), and a reference signal specific to CSI measurement,
The received CSI is:
When it occurs that the first CSI of the unlicensed band and the second CSI of the licensed band occupy the same resource for being fed back, at least one of the band type and validity of the first and second CSI determining priorities of the first CSI and the second CSI; and feeding back CSI having a higher priority according to the determination, wherein the CSI is transmitted from the user terminal. 17. The method of claim 16, wherein transmitting the downlink signals comprises:
directly using the DRS as a reference signal for the CSI measurement;
extending the DRS to include a plurality of reference signal ports for the CSI measurement;
The method of receiving CSI comprising the step of configuring a reference signal for the CSI measurement in the DRS through higher layer signaling. The method of claim 16, wherein the receiving of the CSI comprises:
Receiving CSI measured based on one type of downlink signal in one CSI process; or
A method of receiving CSI comprising the step of receiving CSI measured based on the plurality of types of downlink signals in one CSI process. The method of claim 18, wherein when receiving CSI measured based on the plurality of types of downlink signals in the one CSI process,
constructing, according to interference levels corresponding to different types of downlink signals, signal power estimates of the CSI measurement based on each of the different types of downlink signals; or
Instructing the UE to increase the power of a channel component obtained from CSI measurement corresponding to a predetermined interference level by a predetermined value, or an interference component obtained from CSI measurement corresponding to the predetermined interference level The method of receiving CSI, characterized in that it further comprises the step of reducing the power of the predetermined value. A user terminal comprising a receiver, a transmitter and a processor, the user terminal comprising:
the receiver is configured to receive multiple types of downlink signals from a base station;
the processor is configured to measure channel state information (CSI) for the plurality of types of downlink signals;
The transmitter is configured to feed back CSI measured based on the plurality of types of downlink signals to the base station,
The CSI is measured based on at least one type of downlink signal selected from among the plurality of types, and the at least one type of downlink signals include: the base station within a time period during which the base station transmits downlink data. a reference signal for CSI measurement transmitted by, a search reference signal (DRS) transmitted by the base station, and a reference signal specified for CSI measurement and transmitted by the base station;
The processor is
When it occurs that the first CSI of the unlicensed band and the second CSI of the licensed band occupy the same resource for being fed back, at least one of the band type and validity of the first and second CSI and to determine priorities of the first CSI and the second CSI according to the determination, and to feed back CSI having a higher priority through the transmitter according to the determination. A base station comprising a receiver, a transmitter and a processor, the base station comprising:
the transmitter is configured to transmit a plurality of types of downlink signals for measurement of channel state information (CSI) under the control of the processor;
the receiver is fed back by a user terminal (UE) and is configured to receive the measured CSI based on the plurality of types of downlink signals;
The CSI is measured based on at least one type of downlink signals selected from among the plurality of types, and the plurality of types of downlink signals are: Transmitting within a time period in which the base station transmits downlink data A reference signal for CSI measurement, a search reference signal (DRS), and a reference signal specific to CSI measurement,
The received CSI is:
When it occurs that the first CSI of the unlicensed band and the second CSI of the licensed band occupy the same resource for being fed back, at least one of the band type and validity of the first and second CSI Accordingly, the base station, characterized in that the transmission from the user terminal by the operation of determining the priorities of the first CSI and the second CSI and the operation of feeding back the CSI having a higher priority according to the determination.

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