Patent Description:
With extensive deployment of Long Term Evolution (Long Term Evolution, LTE) networks, to meet a demand of a user for a wireless data service, development of a next-generation wireless communications system (<NUM>) starts to be promoted in the industry. Measurement and reporting of channel state information (Channel State Information, CSI) plays an extremely important role to an LTE system and a <NUM> system.

How to better feed back CSI becomes an urgent technical problem to be resolved.

<NPL>, discloses that CSI reporting in <NUM> NR can be periodic, aperiodic or semi-persistent.

<CIT> discloses how periodic CSI is configured and performed in conventional LTE systems.

<NPL>, discloses, in connection to semi-persistent CSI reporting, possible RRC signalling/DCI signalling/MAC control configure/trigger/stop the CSI reporting.

In view of this, a main objective of this application is to provide a method for periodically feeding back CSI in a feedback time period, to reduce system overheads through automatic feedback of UE.

To describe the technical solutions in the embodiments of this application more clearly, the following briefly describes the accompanying drawings required for the embodiments of this application. Apparently, the accompanying drawings in the following description show merely some embodiments of this application, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

Apparently, the described embodiments are merely some rather than all of the embodiments of this application.

It should be understood that, the technical solutions of the embodiments of this application can be applied to various communications systems, for example, a Global System for Mobile Communications (English full name: Global System of Mobile communication, GSM for short) system, a Code Division Multiple Access (English full name: Code Division Multiple Access, CDMA for short) system, a Wideband Code Division Multiple Access (English full name: Wideband Code Division Multiple Access, WCDMA for short) system, a general packet radio service (English full name: General Packet Radio Service, GPRS for short) system, a Long Term Evolution (English full name: Long Term Evolution, LTE for short) system, an LTE frequency division duplex (English full name: Frequency Division Duplex, FDD for short) system, an LTE time division duplex (English full name: Time Division Duplex, TDD for short), a Universal Mobile Telecommunications System (English full name: Universal Mobile Telecommunication System, UMTS for short), a Worldwide Interoperability for Microwave Access (English full name: Worldwide Interoperability for Microwave Access, WiMAX for short) communications system, a wireless local area network (English full name: Wireless Local Area Network, WLAN for short), and a future fifth generation (English full name: the fifth Generation, <NUM> for short) wireless communications system.

It should also be understood that in the embodiments of this application, a terminal device may be referred to as user equipment (User Equipment, UE for short), a mobile station (Mobile Station, MS for short), a mobile terminal (Mobile Terminal), or the like. The terminal device may communicate with one or more core networks by using a radio access network (Radio Access Network, RAN for short). For example, the terminal device may be a mobile phone (also referred to as a "cellular" phone) or a computer having a mobile terminal. For example, the terminal device may alternatively be a portable, pocket-sized, handheld, computer built-in, or in-vehicle mobile apparatus, which exchanges voice and/or data with the radio access network.

In the embodiments of this application, a base station may be a base transceiver station (Base Transceiver Station, "BTS" for short) in GSM or CDMA, or may be a NodeB (NodeB, "NB" for short) in WCDMA, or may be an evolved NodeB (Evolutional Node B, "eNB or e-NodeB" for short) in LTE, and a network side device in a future <NUM> network.

<FIG> shows a method for feeding back channel state information according to an implementation of this application. The method is interactively performed between a base station and one or more UEs. The communication method specifically includes the following steps:.

The base station sends time configuration signaling and feedback configuration signaling to the UE, where the time configuration signaling is used to set a feedback time period, and the feedback configuration signaling is used to configure one or more feedback cycles, so as to control the user equipment to obtain and feed back a channel state information report during the feedback time period according to the feedback cycle.

The UE receives the time configuration signaling and the feedback configuration signaling from the base station, and periodically sends CSI to the base station in one or more feedback cycles based on the feedback configuration signaling. Specifically, the UE obtains and sends the CSI in the one or more feedback cycles, where the CSI may be generated through measurement in a previous transmission time unit, or may be generated through measurement in a current transmission time unit, or may be obtained through average measurement in a plurality of historical feedback cycles.

The base station receives the CSI from the UE.

According to the foregoing method for feeding back channel state information, the base station can dynamically control, based on a feedback demand of the UE, the UE to periodically feed back the CSI in a specified time, so as to improve feedback efficiency, and reduce system overheads through automatic feedback of the UE.

In an example, the time configuration signaling and the feedback configuration signaling are carried in Radio Resource Control (Radio Resource Control, RRC) signaling for being sent, or carried in MAC-CE signaling for being sent, or may be carried in downlink control information (downlink control information, DCI) signaling for being sent.

Each feedback cycle includes a plurality of transmission time units, and each feedback cycle includes a start transmission time unit and an end transmission time unit. For example, the transmission time unit may be a subframe (subframe), or may be a transmission time interval (Transmission Time Interval, TTI).

In an example, referring to <FIG>, the foregoing time configuration signaling includes reporting activation (reporting activation) signaling and reporting deactivation (reporting deactivation) signaling. The reporting activation signaling is used to determine a start transmission time unit of the feedback time period, and the reporting deactivation signaling is used to determine an end transmission time unit of the feedback time period. The reporting activation signaling and the reporting deactivation signaling may be sent independently. That is, the base station sends the reporting activation signaling to the UE first, and the UE start to feed back a CSI report after receiving the reporting activation signaling; and when the base station sends the reporting deactivation signaling to the UE then, the UE stops feeding back the CSI report. Alternatively, the reporting activation signaling and the reporting deactivation signaling may be sent simultaneously. That is, when the UE receives the reporting activation signaling and the reporting deactivation signaling, a CSI report starts to be fed back at a moment indicated by the reporting activation signaling, and feedback of the CSI report stops at a moment indicated by the reporting deactivation signaling.

According to the present invention, the foregoing time configuration signaling includes reporting activation signaling and reporting duration signaling. The reporting activation signaling is used to determine a start moment of the feedback time period, and reporting duration signaling is used to determine a consecutive transmission time unit in the feedback time period.

In still another example, referring to <FIG>, the foregoing time configuration signaling is further used to configure a start delay or a stop delay, and start delays or stop delays of UEs may be the same or different. The start delay is used to control the user equipment to start CSI feedback after a delay of one or more transmission time units after receiving reporting activation signaling; the stop delay is used to control the user equipment to stop CSI feedback after a delay of one or more transmission time units after receiving reporting deactivation signaling or after duration indicated by delay offset signaling ends. Therefore, the start delay or the stop delay can reduce an error caused by a CSI feedback conflict.

According to the present invention, furthermore, the foregoing feedback configuration signaling includes an offset Z, and the user equipment feeds back the CSI in a corresponding transmission time unit that has an offset of Z transmission time units from a start transmission time unit of each feedback cycle, where Z is an integer greater than or equal to zero. For example, when Z=<NUM>, the user equipment feeds back the CSI in the second transmission time unit that is after a start transmission time unit of one cycle in the feedback time period. When there are a plurality of user equipments, the base station may set Z values of the user equipments, for example, set a Z value of UE1 to <NUM>, and set a Z value of UE2 to <NUM>, so as to avoid a conflict occurring in a process of feeding back the CSI by the UEs. That is, the user equipment feeds back an information state report at a moment that has an offset of Z TTIs from a start moment of a frame in the feedback time period.

In another example, one piece of CSI may be fed back in each feedback cycle. For example, one piece of CSI may include a channel quality indicator (channel quality indicator, CQI), a precoding matrix indication (precoding matrix indication, PMI), and a rank indication (rank indication, RI). The foregoing three indications are only used as examples, and are not used to limit CSI composition in this application.

Optionally, each piece of CSI may be further fed back in a plurality of feedback cycles. Specifically, according to the present invention, the feedback configuration signaling is used to configure N cycles, the CSI includes M parts, and the M parts is sent by using M cycles, where N≥M≥<NUM>, and both N and M are positive integers. For example, the foregoing CSI may include two parts, and the two parts are any combination of a CQI, a PMI, and an RI. Referring to <FIG>, when CSI is divided into a part that includes a CQI and a PMI and a part that includes an RI, in a process of feeding back the CSI, the CQI and the PMI are fed back in one cycle, and the RI is fed back in a next cycle; in other words, one complete CSI feedback is completed in two cycles. Therefore, when there is relatively much content in the CSI, the CSI can be consecutively fed back by using a plurality of cycles, so as to ensure timely CSI feedback.

In still another example, one feedback cycle includes a plurality of transmission time units, and the CSI is fed back in one of the transmission time units. For ease of description, the transmission time unit used to feed back the CSI is referred to as an effective time unit. The effective time unit is only used to indicate a transmission time unit used to feed back the CSI and is not used for limitation. For example, the transmission time unit may be a subframe, that is, the CSI is fed back in one subframe.

Optionally, the base station further sends data channel signaling to the UE, where the data channel signaling is used to indicate whether the CSI is allowed to be fed back in an effective time unit by using an uplink data channel (PUSCH). Specifically, when there is not only the uplink data channel (PUSCH), but also an uplink control channel (PUCCH) in the effective time unit, the data channel signaling is used to indicate whether the uplink data channel is allowed to be used. When the uplink data channel is allowed to be used in the effective time unit, the CSI is fed back by using the uplink data channel. When the uplink data channel is not allowed to be used in the effective time unit, the CSI is fed back by using the uplink control channel. For example, the data channel signaling may be carried by RRC signaling; when content of the data channel signaling is set to <NUM>, it indicates that the uplink data channel is allowed to be used in the effective time unit; and when content of the data channel signaling is set to <NUM>, it indicates that the uplink data channel is not allowed to be used in the effective time unit. Therefore, when there is an uplink data channel resource, the resource can be effectively used, so as to improve CSI feedback efficiency.

Another embodiment of this application provides an apparatus <NUM> for feeding back channel state information that is applied to a wireless communications system. A solid structure of the apparatus <NUM> is shown in <FIG>. The apparatus <NUM> may be a base station, or the apparatus <NUM> may be an application-specific integrated circuit (Application-Specific Integrated Circuit, ASIC) or a chip for implementing a related function. The apparatus <NUM> includes a processor <NUM>, a memory <NUM>, a baseband processor <NUM>, a transceiver <NUM>, an antenna <NUM>, a bus <NUM>, and an I/O interface <NUM>.

Specifically, the processor <NUM> controls an operation of the apparatus <NUM>. The processor may be a general purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array, or another programmable logic device. The memory <NUM> may include a read-only memory and a random access memory, and provides an instruction and data to the processor <NUM>, where a part of the memory <NUM> may further include a non-volatile random access memory (NVRAM).

The baseband processor <NUM> is configured to generate a baseband signal (for example, time configuration signaling and feedback configuration signaling), or parse a received baseband signal to obtain useful information. The baseband processor includes a channel encoder and a modulator. The channel encoder can improve robustness of the baseband signal, overcome interference and fading in a wireless transmission environment, and reduce an error generated during transmission. The modulator may select an appropriate signal modulation manner based on the wireless transmission environment.

The transceiver <NUM> includes a transmitter circuit and a receiver circuit. The transmitter circuit is configured to perform an up-conversion operation on the baseband signal generated by the baseband processor <NUM>, so as to obtain a high frequency carrier signal, and the high frequency carrier signal is transmitted by using the antenna <NUM>. The receiver circuit performs a down-conversion operation on the high frequency signal received by the antenna <NUM>, so as to obtain a low frequency baseband signal. There are one or more antennas <NUM>. The apparatus <NUM> may further include the I/O interface <NUM>, and the I/O interface <NUM> includes an input/output device such as a keyboard, an audio monitoring unit, and/or a touchscreen.

Components of the apparatus <NUM> are coupled together by using a bus <NUM>. In addition to a data bus, the bus <NUM> further includes a power bus, a control bus, and a status signal bus. However, for clear description, various types of buses in the figure are marked as the bus <NUM>. It should be noted that, the foregoing description of an access point structure can be applied to a subsequent embodiment.

The baseband processor <NUM> is configured to generate the time configuration signaling and the feedback configuration signaling, where the time configuration signaling is used to set a feedback time period, and the feedback configuration signaling is used to configure one or more feedback cycles.

The transceiver <NUM> is configured to: send the time configuration signaling and the feedback configuration signaling, and receive CSI periodically sent by user equipment in one or more feedback cycles during the feedback time period.

Optionally, the feedback cycle configuration includes an offset Z, and the feedback configuration signaling is used to configure that the CSI is fed back in a corresponding transmission time unit that has an offset of Z transmission time units from a start transmission time unit of each feedback cycle, where Z is an integer greater than or equal to zero.

Optionally, the feedback configuration signaling is used to configure N cycles, the CSI includes M parts, and the M parts are sent by using M cycles, where N≥M≥<NUM>, and both N and M are positive integers.

Optionally, the feedback cycle includes at least one or more transmission time units, and the baseband processor further generates data channel signaling, where the data channel signaling is used to indicate whether an uplink data channel is allowed to be used in one transmission time unit of the feedback cycle; and when the data channel signaling indicates that the uplink data channel is allowed to be used in the transmission time unit, the CSI is fed back in the transmission time unit by using the uplink data channel.

An embodiment of this application provides an apparatus for feeding back channel state information that is applied to a wireless communications system. A solid structure of the apparatus is shown in <FIG>. The apparatus may be UE, or the apparatus may be an application-specific integrated circuit (English: Application-Specific Integrated Circuit, ASIC for short) or a chip for implementing a related function. The apparatus <NUM> includes a processor <NUM>, a memory <NUM>, a baseband processor <NUM>, a transceiver <NUM>, an antenna <NUM>, a bus <NUM>, and an I/O interface <NUM>. Composition and a function of each component in the apparatus <NUM> have been described in detail in the embodiment shown in <FIG>, and are not described again.

The transceiver <NUM> is configured to receive time configuration signaling and feedback configuration signaling, where the time configuration signaling is used to set a feedback time period, and the feedback configuration signaling is used to configure one or more feedback cycles.

The baseband processor <NUM> is configured to periodically obtain and send CSI in one or more feedback cycles during the feedback time period.

Optionally, the feedback cycle configuration includes an offset Z, and the user equipment feeds back the CSI in a corresponding transmission time unit that has an offset of Z transmission time units from a start transmission time unit of each feedback cycle, where Z is an integer greater than or equal to zero.

Optionally, the feedback cycle includes at least one or more transmission time units, where the transceiver further receives data channel signaling, where the data channel signaling is used to indicate whether an uplink data channel is allowed to be used in one transmission time unit of the feedback cycle; and when the data channel signaling indicates that the uplink data channel is allowed to be used in the transmission time unit, the baseband processor feeds back the CSI in the transmission time unit by using the uplink data channel and sends the CSI by using the transceiver.

The foregoing mainly describes the solutions provided by the embodiments of this application from a perspective of interaction between network elements. It can be understood that, to implement the foregoing functions, network elements, for example, UE, a base station, and a core network entity, include corresponding hardware structures and/or software modules for performing the functions. A person of ordinary skill in the art should easily be aware that, in combination with the examples described in the embodiments disclosed in this specification, units and algorithm steps may be implemented by hardware or a combination of hardware and computer software. Whether a function is performed by hardware or hardware driven by computer software depends on particular applications and design constraints of the technical solutions.

A controller/processor configured to perform functions of the base station, the terminal, or the core network apparatus in this application may be a central processing unit (CPU), a general purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The controller/processor may implement or execute various example logical blocks, modules, and circuits described with reference to content disclosed in this application. Alternatively, the processor may be a combination implementing a computing function, for example, a combination of one or more microprocessors, or a combination of the DSP and a microprocessor.

Method or algorithm steps described in combination with the content disclosed in this application may be implemented by hardware, or may be implemented by a processor by executing a software instruction. The software instruction may be formed by a corresponding software module. The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable magnetic disk, a CD-ROM, or a storage medium of any other form known in the art. For example, a storage medium is coupled to a processor, so that the processor can read information from the storage medium or write information into the storage medium. Certainly, the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. In addition, the ASIC may be located in user equipment. Certainly, the processor and the storage medium may exist in the user equipment as discrete components.

A person skilled in the art should be aware that in the foregoing one or more examples, functions described in this application may be implemented by hardware, software, firmware, or any combination thereof. When the present invention is implemented by software, the foregoing functions may be stored in a computer-readable medium or transmitted as one or more instructions or code in a computer-readable medium. The computer-readable medium includes a computer storage medium and a communications medium, where the communications medium includes any medium that enables a computer program to be transmitted from one place to another place. The storage medium may be any available medium accessible to a general-purpose or dedicated computer.

Claim 1:
A method for feeding back channel state information, CSI, applied to a wireless communications system, and comprising:
receiving, by a user equipment, time configuration signaling and feedback configuration signaling, wherein the time configuration signaling comprises reporting activation signaling and reporting duration signaling, wherein the reporting activation signaling is used to determine a start moment of a feedback time period during which the user equipment feeds back CSI, and the reporting duration signaling is used to determine a consecutive transmission time unit of the feedback time period, and wherein the feedback configuration signaling is used to configure two or more feedback cycles during the feedback time period, each feedback cycle including a plurality of transmission time units, wherein the feedback configuration signaling comprises an offset Z, and the feedback configuration signaling is used to configure feeding back the CSI in a corresponding transmission time unit that has an offset of Z transmission time units from a start transmission time unit of each feedback cycle, wherein Z is an integer greater than or equal to zero, wherein the feedback configuration signaling is used to configure N cycles, the CSI comprises M parts, and the M parts are sent by using M cycles from the N cycles, wherein N≥M≥<NUM>, and both N and M are positive integers.; and
periodically obtaining and sending, by the user equipment, CSI in the two or more feedback cycles during the feedback time period.