Patent Description:
This application relates to radio access networks and, in particular, to apparatus for determining channel state information by requesting multiple aperiodic channel state information (CSI) reports.

Wireless communication systems send and receive data at increasing rates using a variety of transmission modes, encoding techniques and modulation schemes. These communication systems employ multiple antennas and modulation schemes such as quadrature amplitude modulation (QAM) as well as transmission techniques such as carrier aggregation (CA) and orthogonal frequency division multiple access (OFDMA). The systems support downlink data rates and upload data rates greater than one gigabit per second (<NUM> Gbit/s). The communication systems may be used to send a small number of high-data rate communications or a larger number of lower data rate communications. The peak rates assume channels having minimal noise and interference. Wireless channels, however, are subject to noise, multipath fading, inter-symbol interference, Doppler shifts due to mobile user equipment (UE) and other noise or distortion sources.

The communications standards include a number of encoding techniques for overcoming noise and distortion in a channel. These include encoding the data with a forward error correction (FEC), and employing a hybrid automatic repeat request (HARQ) acknowledgement (ACK) scheme to resend corrupted data.

The status of the channel or channels used to transmit data may change rapidly, especially for mobile UEs. It is desirable for a base station, such as an evolved Node B (eNB) or generation Node B (gNB) to be able to rapidly and continually determine channel status for a number of channels in order to determine which channels to use and what type of encoding and transmission techniques to use on each of the channels so that the data in each channel is transmitted in a way that compensates for the status of the channels.

The document by <NPL>, discusses the specification impacts of beamformed CSI-RS configuration. <CIT> relates to channel state information being reported in periodic and aperiodic reports for multiple component carriers or serving cells. Channel state information may be reported for a subset of aggregated downlink carriers or serving cells. For an aperiodic report, the carrier(s)/serving cell(s) for which channel state information is reported are determined based on the request for the aperiodic report. When a CQI/PMI/RI report and a HARQ ACK/NACK report coincide in a subframe, the HARQ ACK/NACK report is transmitted on PUCCH, and the CQI/PMI/RI report is transmitted on PUSCH.

Preferred embodiments of the invention are stipulated in the dependent claims.

The following detailed description refers to the accompanying drawings. The same reference numbers may be used in different drawings to identify the same or similar elements. In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of various embodiments. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the various embodiments may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the various embodiments with unnecessary detail.

<FIG> shows a wireless communication system <NUM> that includes a core network <NUM> which controls a number of base stations, for example, base stations 112A, 112B and 112C. The base stations, in turn, provides communications services to one or more user equipment (UE) 114A1, 114A2, 114B1, 114B2, 114C1 and 114C2 in respective geographical areas 115A, 115B and 115C. The geographical areas are known as cells and the cell serving a particular UE is known as the serving cell for that UE. Each cell, in turn, may be divided into a plurality of sectors. In a multiple-input multiple-output (MIMO) or multiple-input single-output (MISO) system, UEs in different sectors may be served individually using beam forming techniques that define a matrix of spatially multiplexed channels. While a base station generally provides communication services to UE in its serving cell, it may also provide services to UE in one or more neighboring cells. As shown in <FIG>, for example, the base station 112C provides communication services to the UE 114C1 in cell 115C as well as to UE 114A2 in cell 115A. Conversely, a base station may provide multiple transmission points to a UE.

The communication system <NUM> may include, without limitation, an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN) or a wireless personal area network (WPAN). The network <NUM> may be compatible with one or more wireless communication protocols including, without limitation Institute of Electrical and Electronic Engineers (IEEE) <NUM> wireless technology (WiMax), IEEE <NUM> wireless technology (ZigBee), IEEE <NUM> wireless technology (WiFi) including IEEE <NUM>. 11ad, which operates in the <NUM> millimeter wave spectrum, various other wireless technologies such as global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radio access network (GERAN), universal mobile telecommunications system (UMTS), UMTS terrestrial radio access network (UTRAN), or other <NUM>, <NUM>, <NUM>, <NUM>, etc. technologies either already developed or to be developed.

The base stations <NUM> may be, for example, fixed stations that communicate with one or more UEs <NUM> which belong to a service defined by the core network <NUM>. A base station, also known as a base transceiver station (BTS) may be an evolved Node B (eNB), a generation Node B (gNB), a macrocell, microcell, picocell or femtocell. One or more of the base stations <NUM> may also be wireless access points.

The UE <NUM> may be a mobile device or a fixed device that operates according to a mobile protocol. The UE <NUM> may include, without limitation, a tablet computer, a wearable computer such as a smart watch or head-mounted display, a personal digital assistant (PDA), a game console, a portable media player, a mobile telephone and/or a smart phone.

Communications sent from the base station <NUM> to the UE <NUM> are referred to as downlink (DL) communications while communications sent from the UE <NUM> to the base station <NUM> are referred to as uplink (UL) communications. The wireless communication system <NUM> may be a MIMO system having multiple transmit antennas and multiple receive antennas or a MISO system having multiple transmit antennas and a single receive antenna. The multiple antennas may be coupled to the base station and/or the UE. The system <NUM> may also be a single input, single output (SISO) system having a single transmit antenna and a single receive antenna.

The example communication system may use between one and five frequency bands having bandwidths of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or more than <NUM>. Furthermore, the communication system may perform carrier aggregation (CA) in which multiple carriers may be aggregated to send a single data stream. As many as <NUM> carriers can be aggregated in CA.

As used herein, the term "circuitry" may refer to, be part of, or include a core processor, a digital signal processor (DSP), a field-programmable gate array (FPGA), an Application Specific Integrated Circuit (ASIC), a programmable logic device (PLD) an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality.

Embodiments described herein may be implemented in a system using any suitably configured hardware and/or software. <FIG> illustrates, for one embodiment, example components of two electronic devices <NUM> and <NUM>. In embodiments, the electronic device <NUM> may be incorporated into, or otherwise be a part of an eNB or gNB, or some other suitable electronic device. Electronic device <NUM> may be incorporated into or otherwise a part of a UE. In some embodiments, the electronic device <NUM> may include application circuitry <NUM>, baseband circuitry <NUM>, Radio Frequency (RF) circuitry <NUM>, front-end module (FEM) circuitry <NUM> and one or more antennas <NUM>, coupled together at least as shown.

For example, the application circuitry <NUM> may include circuitry such as, but not limited to, one or more single-core or multi-core processors (not separately shown). The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, DSPs, etc.).

The baseband circuitry <NUM> may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry <NUM> and to generate baseband signals for a transmit signal path of the RF circuitry <NUM>. Baseband processing circuity <NUM> may interface with the application circuitry <NUM> for generation and processing of the baseband signals and for controlling operations of the RF circuitry <NUM>. For example, in some embodiments, the baseband circuitry <NUM> may include a second generation (<NUM>) baseband processor 204A, third generation (<NUM>) baseband processor 204B, fourth generation (<NUM>) baseband processor 204C, and/or other baseband processor(s) 204D for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (<NUM>), <NUM>, etc.).

The baseband circuitry <NUM> (e.g., one or more of baseband processors 204A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry <NUM>. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry <NUM> may include Fast-Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry <NUM> may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry <NUM> may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 204E of the baseband circuitry <NUM> may be configured to run elements of the protocol stack for signalling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 204F. The audio DSP(s) 204F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments.

The baseband circuitry <NUM> may further include memory/storage <NUM>. The memory/storage <NUM> may be used to load and store data and/or instructions for operations performed by the processors of the baseband circuitry <NUM> Memory/storage for one embodiment may include any combination of suitable volatile memory and/or non-volatile memory. The memory /storage <NUM> may include any combination of various levels of memory /storage including, but not limited to, read-only memory (ROM) having embedded software instructions (e.g., firmware), random access memory (e.g., dynamic random access memory (DRAM)), cache, buffers, etc. The memory/storage <NUM> may be shared among the various processors or dedicated to particular processors.

Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry <NUM> and the application circuitry <NUM> may be implemented together such as, for example, on a system on a chip (SOC).

RF circuitry <NUM> may include one or more receive signal paths which may include circuitry to down-convert RF signals received from the FEM circuitry <NUM> and provide baseband signals to the baseband circuitry <NUM>.

In some embodiments, the RF circuitry <NUM> may include a one or more receive signal paths and transmit signal paths. The receive signal path of the RF circuitry <NUM> may include mixer circuitry 206A, amplifier circuitry 206B and filter circuitry 206C. The transmit signal path of the RF circuitry <NUM> may include filter circuitry 206C and mixer circuitry 206A. RF circuitry <NUM> may also include synthesizer circuitry 206D for synthesizing a frequency for use by the mixer circuitry 206A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 206A of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry <NUM> based on the synthesized frequency provided by synthesizer circuitry 206D. The amplifier circuitry 206B may be configured to amplify the down-converted signals and the filter circuitry 206C may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry <NUM> for further processing. In some embodiments, the output baseband signals may be, without limitation, low intermediate frequency (LIF), very low intermediate frequency (VLIF) or zero-frequency baseband signals. In some embodiments, mixer circuitry 206A of the receive signal path may comprise, without limitation, active or passive mixers.

In some embodiments, the mixer circuitry 206A of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 206D to generate RF output signals for the FEM circuitry <NUM>. The baseband signals may be provided by the baseband circuitry <NUM> and may be filtered by filter circuitry 206C. The filter circuitry 206C may include a BPF or a high-pass filter (HPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206A of the receive signal path and the mixer circuitry 206A of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion respectively. In some embodiments, the mixer circuitry 206A of the receive signal path and the mixer circuitry 206A of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 206A of the receive signal path and the mixer circuitry 206A may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 206A of the receive signal path and the mixer circuitry 206A of the transmit signal path may be configured for super-heterodyne operation.

In these alternate embodiments, the RF circuitry <NUM> may include analog-to-digital converter (ADC) circuitry (not shown) and digital-to-analog converter (DAC) circuitry (not shown) and the baseband circuitry <NUM> may include a digital baseband interface to communicate with the RF circuitry <NUM>.

In some dual-mode embodiments, separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206D may be a fractional-N synthesizer or a fractional N/N+<NUM> synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 206D may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

The synthesizer circuitry 206D may be configured to synthesize an output frequency for use by the mixer circuitry 206A of the RF circuitry <NUM> based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 206D may be a fractional N/N+<NUM> synthesizer.

Synthesizer circuitry 206D of the RF circuitry <NUM> may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+<NUM> (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, frequency input to the synthesizer 206D may be provided by a voltage controlled oscillator (VCO) (not shown), although that is not a requirement. Divider control input for the synthesizer 206D may be provided by either the baseband circuitry <NUM> or the applications processor <NUM> depending on the desired output frequency.

In some embodiments, synthesizer circuitry 206D may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a local oscillator (LO) frequency (fLO). In some embodiments, the RF circuitry <NUM> may include an IQ/polar converter.

FEM circuitry <NUM> may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas <NUM>, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry <NUM> for further processing.

In some embodiments, the communication device <NUM> may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input/output (I/O) interface as described in more detail below. In some embodiments, the communication device <NUM> described herein may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a gaming system, a smartphone, a smart watch, wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the communication device <NUM> may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. For example, the communication device <NUM> may include one or more of a keyboard, a keypad, a touchpad, a display, a sensor, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, a power supply interface, one or more antennas, a graphics processor, an application processor, a speaker, a microphone, and other I/O components. The display may be a liquid crystal device (LCD), electroluminescent (EL) or light emitting diode (LED) screen that may include a touch screen input device. The sensor may include a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

The antennas <NUM> may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas, fractal antennas or other types of antennas suitable for transmission of RF signals. In some MIMO or MISO embodiments, the antennas <NUM> may be effectively separated and/or polarized to take advantage of spatial diversity and the different channel characteristics among the different transmission points of the base station to implement multi-layer communication. Alternatively, or in addition, the antennas <NUM> may be configured in a beam-forming array to direct a transmitted beam toward a particular UE to implement spatial multiplexing and/or spatial diversity and/or to determine the angle of arrival (AoA) of a signal received from a UE.

Although the communication device <NUM> is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media, including optical storage media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.

As described above, although the circuitry used by device <NUM> is described as implementing a base station, such as an eNB/gNB, similar circuitry may be used to implement a UE. <FIG> includes a block diagram of an example UE communication device <NUM> in accordance with some embodiments. The device may be a UE, for example, such as any of the UEs <NUM> shown in <FIG>. The physical layer circuitry <NUM> may perform various encoding and decoding functions that may include formation of baseband signals for transmission and decoding of received signals. The communication device <NUM> may also include media access control (MAC) layer circuitry <NUM> for controlling access to the wireless medium. The communication device <NUM> may further include processing circuitry <NUM>, such as one or more single-core or multi-core processors, and memory <NUM> arranged to perform the operations described herein. The physical layer circuitry <NUM>, MAC circuitry <NUM>, transceiver circuitry <NUM>, processing circuitry <NUM>, memory <NUM> and interface circuitry <NUM> may be the same as the base station circuitry <NUM>, described above, and may handle various radio control functions that enable communication with one or more radio networks compatible with one or more radio technologies. The radio control functions may include signal modulation, encoding, decoding, radio frequency shifting, etc..

For example, similar to the device <NUM> shown in <FIG>, in some embodiments, communication may be enabled with one or more of a WMAN, a WLAN, and aWPAN. In some embodiments, the communication device <NUM> can be configured to operate in accordance with 3GPP standards or other protocols or standards, including ZigBee, WiMax, Wi-Fi, WiGig, GSM, EDGE, GERAN, UMTS, UTRAN, or other <NUM>, <NUM>, <NUM>, <NUM>, etc. technologies either already developed or to be developed. The communication device <NUM> may include transceiver circuitry <NUM> to enable communication with other external devices wirelessly and interfaces <NUM> to enable wired communication (including optical fiber communication) with other external devices. As another example, the transceiver circuitry <NUM> may perform various transmission and reception functions such as conversion of signals between a baseband range and a Radio Frequency (RF) range.

The example UE device <NUM> may also include antennas <NUM> that may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip, fractal antennas or other types of antennas suitable for transmission of RF signals. In some MIMO embodiments, the antennas <NUM> may be effectively separated anchor polarized to take advantage of spatial diversity and the different channel characteristics among the different transmission points of the base station to support multi-layer communication. Alternatively, or in addition, the antennas <NUM> may be configured in a beam-forming array to direct a transmitted beam toward a particular base station and/or to determine the angle of arrival (AoA) of a signal received from a base station.

Although the communication device <NUM> is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including DSPs, and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, FPGAs, PLDs, ASICs, RFICs and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements. Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein.

In embodiments where the electronic device <NUM> and/or <NUM> is, implements, is incorporated into, or is otherwise part of a UE, the physical layer circuitry <NUM> and MAC layer circuitry <NUM> may be configured to determine, based on one or more signals received from an eNB/gNB, whether multi-shot aperiodic channel state information (CSI) reporting is configured for the UE. Transceiver circuitry <NUM> may be configured to receive an aperiodic CSI request which is processed in the physical layer circuitry <NUM>, where the aperiodic CSI request is to trigger the multi-shot aperiodic CSI reporting by the UE and insert and encode multiple aperiodic CSI reports into the PUCCH or PUSCH for transmission to the base station in response to the aperiodic CSI request.

In embodiments where the electronic device <NUM> and/or <NUM> is, implements, is incorporated into, or is otherwise part of a base station, the baseband circuitry <NUM> may be configured to determine whether a user equipment (UE) should be configured for an aperiodic channel state information (CSI) reporting process. The application circuitry <NUM> may send a message, via the RF circuitry <NUM>, to configure the UE to send multiple aperiodic CSI reports and, then, may send a CSI request as a part of a channel control message, for example, downlink control information (DCI), to trigger the multi-shot aperiodic CSI reporting by the UE. The application circuitry <NUM> may also process the received multi-shot aperiodic CSI reports to cause the base station to reconfigure its communications with the UE to compensate for the reported channel conditions.

As shown in <FIG>, each base station <NUM> may communicate with UEs in the serving cell <NUM> of the base station as well as with UEs in neighboring cells. Conversely, using coordinated multipoint (CoMP), a UE may communicate with multiple base stations. At any given time, each base station has a number of communications in process. The status of a channel used to communicate with one or more UE may change quickly, especially for mobile UE. Thus, it is beneficial for each base station <NUM> to be able to quickly determine any change in channel status so that the base station <NUM> may dynamically adjust the channels used, the bandwidth of the channels as well as encoding, modulation and transmission techniques used on the channels to ensure that the most important data is transmitted in a way to reduce reception errors and otherwise increase throughput.

In order to determine the status of data channels between the base stations <NUM> and the UEs <NUM>, Long Term Evolution Advanced (LTE-A) supports two types of CSI - periodic and aperiodic. Periodic CSI reporting is mainly used to indicate current encoding and modulation techniques being used as well as channel status of the downlink channel at the UE on a relatively long-term basis. Periodic CSI reports are provided by the UE in accordance with a predefined reporting time schedule configured by a serving base station or serving eNB/gNB using a resource control message sent via higher layer signalling (e.g., radio resource control (RRC) signalling and the like). Periodic CSI reporting usually has relatively low overhead. By contrast, in one embodiment, multi-shot aperiodic CSI reporting may be used to provide relatively large and relatively more detailed reporting in a multiple reporting instances based on one dynamic CSI request triggered by the serving cell/serving eNB/gNB using the one CSI request sent in a channel control message, for example in DCI of a physical downlink control channel (PDCCH) or in a media access control (MAC) control element (CE).

<FIG> are data diagrams that illustrate the structure of a down link (DL) data frame. As shown in <FIG>, each frame includes <NUM> subframes and each sub-frame includes two slots. <FIG> illustrates the structure of a slot. Each slot includes seven symbols in the time domain, where each symbol includes a number, M, modulated subcarriers in the frequency domain. The modulated subcarriers in a slot are divided into resource blocks, where each resource block includes seven symbols and each symbol is represented by <NUM> modulated subcarriers. The subcarriers are mutually orthogonal having a spacing of <NUM>. Each subcarrier may be modulated using quadrature phase shift keying (QPSK), <NUM> quadrature amplitude modulation (16QAM), 64QAM or 256QAM. Multiple resource blocks may be divided among multiple UEs. In order to effectively transmit downlink data, it is desirable for the base station to continually know the characteristics of the channel on each resource block to each UE being served.

Uplink (UL) frames have a similar format but may have fewer subcarriers as uplink transmissions may use single carrier frequency division multiplexing (SC-FDMA). The uplink transmissions may also use OFDMA.

In LTE, aperiodic CSI requests are sent from the base station(s) to the UEs in DCIs. The PDCCH is allocated in the resource blocks by the base station. As described above, a base station may concurrently determine the status of several channels using an aperiodic CSI request. In CA, multiple CSI corresponding to multiple carriers (or serving cells) can be requested by the serving base station in accordance with Table <NUM>. The set of serving base stations for reporting corresponding to CSI request fields '<NUM>' and '<NUM>' may be configured using a resource control message sent via radio resource control (RRC) signalling.

In transmission mode <NUM>, for multi-antenna base stations, multiple CSI reports corresponding to multiple CSI processes on the same serving frequency but on different channels (transmission points) for each base station can be requested by a serving base station in accordance to the Table <NUM>. The set of CSI processes for reporting corresponding to CSI request fields '<NUM>', '<NUM>' and '<NUM>' may be configured using RRC signalling.

The aperiodic CSI triggering is performed by setting, in the DCI formats <NUM> or <NUM>, the Modulation and Coding Scheme (MCS) and resource allocation size in such way that the MCS index, denoted as IMCS, is <NUM> and resource allocation size (number of resource blocks), denoted as NPRB, to be less than x (e.g., x = <NUM> or <NUM>). The base station sends the DCI in the Physical Downlink Control Channel (PDCCH) or the enhanced PDCCH.

The CSI report includes detailed information regarding the status of channels between a UE and one or more base stations. Each report includes a rank indicator (RI), a precoding matrix indicator (PMI), a precoding type indicator (PTI) and a channel quality indicator (CQI) for each DL channel. In response to an aperiodic CSI request, the UE obtains this information for the requested channel or channels and sends it to the requesting base station. The CSI reports may be encoded by the UE and sent from the UE to the base station in the physical uplink shared channel (PUSCH). As described below, according to the invention the CSI reports are encoded and sent via the PUCCH.

<FIG> are data diagram showing example channel control messages, in this case, a format <NUM> DCI and a format <NUM> DCI, respectively. The format <NUM> DCI includes a <NUM> bit flag <NUM> that differentiates the format <NUM> DCI from a format 1A DCI, a <NUM> bit hopping flag <NUM>, a <NUM> bit hopping resource allocation ( NUL hop) field <NUM>, a resource block assignment field <NUM> that has between <NUM> and <NUM> bits, a <NUM> bit field <NUM> containing modulation coding scheme (MCS), redundancy version (RV) and new-data indicator (NDI) subfields a <NUM> bit power control command (TPC) field <NUM> for the physical uplink shared channel (PUSCH), a <NUM> bit cyclic shift field <NUM> for the demodulation reference (RM RS) signal, a <NUM> bit uplink (UL) index field <NUM>, a <NUM> bit downlink assignment index (DAI) field <NUM> and a <NUM> or <NUM> bit CSI request field. The UL index and DAI fields are only used for time division duplex (TTD) transmissions.

The format <NUM> DCI includes a carrier indicator field <NUM> that has between <NUM> and <NUM> bits, a resource block assignment field <NUM> having between <NUM> and <NUM> bits, a <NUM> bit TPC power control field <NUM>, a <NUM> bit cyclic shift for DM RS and orthogonal cover code (OCC) index field <NUM>, a <NUM> or <NUM> bit CSI request field <NUM>, a <NUM> bit sounding reference signal (SRS) request field <NUM>, a <NUM> bit resource allocation type field <NUM>, a <NUM> bit field <NUM> containing a first sub field for the modulation coding scheme and redundancy version (MCS and RV) for transport block <NUM> (TB1) and a second subfield containing the NDI for TB1, a <NUM> bit field <NUM> containing the MCS, RV and NDI for transport block <NUM> (TB2), and a field <NUM> having between <NUM> and <NUM> bits that defines the precoding index and number of layers.

In the case of aperiodic CSI feedback, the UE can send a DCI including a CSI request in every sub-frame. This gives the network flexibility in assigning the resources to the UE for CSI transmission. A drawback is that there may be additional overhead associated with the transmission of the triggering DCIs on PDCCH or enhanced PDCCH (EPDCCH) in every sub-frame. In a Full Dimension Multiple Input Multiple Output (FD-MIMO) system with many UEs the overhead may be significant because each DCI may have as many as <NUM> bits. Thus, the DCI including the CSI request for each UE may occupy <NUM> bits in each downlink sub-frame. Some methods to reduce the control channel overhead should be considered.

According to the invention, multi-shot CSI reporting is provided. In accordance with various implementations, a UE receives a CSI request in DCI or MAC CE that activates multi-shot CSI calculation and reporting. The number of reports and/or periodicity can be configured using higher layer signalling such as RRC signalling. In the other embodiments, the number of CSI reports can be also determined by another DCI or MAC CE which releases the multi-shot CSI reporting at the UE. The UE is configured to encode and send the CSI reports by signalling data in the DCI containing the aperiodic CSI request. As an alternative to sending the DCI containing the CSI request in the PDCCH, the base station sends, according to the invention, CSI requests using a MAC CE.

In various embodiments, the base station can configure the UE with multi-shot aperiodic CSI reporting using a resource control message sent via higher layer signalling such as RRC signalling and the like. This signalling may include the index, I, of an initial sub-frame into which the CSI report is to be inserted, the configuration of CSI reporting periodicity, P, and the number of CSI report instances, N, a bit map, and/or reporting parameter threshold values. After the UE has been configured, the multi-shot aperiodic CSI reporting is triggered by the reception of a DCI (e.g., DCI Format <NUM> or <NUM>) with a non-zero CSI request field. Responsive to receiving this CSI request, the UE performs CSI calculation and reporting of CSI for N uplink sub-frames with periodicity of P sub-frames.

In other embodiments, the number of CSI reports can be determined by another DCI, which releases the multi-shot aperiodic CSI reporting at the UE. In yet other embodiments, the UE may be configured by the DCI or MAC CE without using any higher level signalling.

<FIG> shows examples of these embodiments for a Frequency Division Duplex (FDD) system. The embodiment is described with reference to a single base station <NUM> and a single UE <NUM>. It is contemplated, however, that it may be implemented in systems having multiple base stations and multiple UEs. When a UE has multiple serving base stations, any one of the base stations can receive a CSI report including the status of the channels between the UE and the other base stations as described above with reference to Tables <NUM> and <NUM>.

At <NUM>, the base station <NUM> may configure the UE <NUM> using higher-layer signalling such as RRC signalling. For a single aperiodic CSI request, the base station <NUM> may signal an initial sub-frame index, I, identifying the sub-frame in which the UE is to insert and encode the CSI report. For multi-shot CSI requests, the sub-frame index may indicate when the first CSI report is to be sent and the base station <NUM> may further configure the UE device in several ways for multi-shot CSI reports. First, the base station may configure the UE with only a period value P. Second, the base station may configure the UE with both a period value P and a number of CSI reports N. Third, the base station may configure the UE with a bit-map where each bit corresponds to a sub-frame in which the CSI report is to be generated, inserted and encoded. Fourth, the base station may send a period value P and one or more parameters to the UE describing threshold values (maximum and/or minimum) for one or more of the values in the CSI report. Using the higher level signalling, the base station may also assign the serving cells (component carriers) for the UE to the first and second sets, as described above with reference to Table <NUM> or it may assign the CSI processes for the different layers to sets <NUM> and <NUM> as described above with reference to Table <NUM>. The higher-layer signalling may also configure the UE to insert and encode the CSI reports in the physical uplink control channel (PUCCH) rather than the PUSCH to limit the impact of the increased reporting on the transmission of uplink data. Upon receiving the RCC signalling, the UE <NUM> extracts the sub-frame index, the values P and N, the bit map and/or the parameter threshold values and uses these values to configure processing of the CSI reports.

The remainder of <FIG> illustrates the first two alternatives described above. At <NUM>, the base station <NUM> sends a DCI or MAC CE with a CSI request. Depending on how the UE has been configured, it may respond by inserting a first CSI report <NUM> into the sub-frame identified by the initial sub-frame index, I, and then by inserting subsequent CSI reports <NUM>, <NUM> and <NUM> with a period of P sub-frames until a deactivating DCI or MAC CE <NUM> is received. Such a deactivating DCI may, for example, have a non-zero DCI field, but zero-valued Transmit Power Control (TPC) command and Demodulation reference signal (DM-RS) shift fields. According to the invention, the MAC CE is sent to de-activate CSI reporting. According to the second alternative, when the UE has been configured to send N CSI reports, the UE may insert and encode the subsequent CSI reports <NUM>, <NUM> and <NUM> into sub-frames with a period of P until N reports have been sent. In this alternative, there is no deactivation DCI, as indicated by <NUM> being a dashed line.

<FIG> illustrates the third alternative, described above, in which the CSI reports are generated and transmitted in sub-frames determined from a bit-map. In the third alternative, at <NUM>, the base station <NUM>, using higher level signalling, configures the UE with a bit-map <NUM> describing die sub-frames in which a CSI report is to be inserted. As shown in <FIG>, the CSI request received at <NUM> aligns the bit-map <NUM> with the sub-frames such that the UE inserts a CSI report for each sub-frame <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> corresponding to a "<NUM>" valued bit in the bitmap <NUM>. No CSI report is sent for sub-frames corresponding to "<NUM>" valued bits in the bitmap. The bit-map <NUM> may be retained by the UE and used for subsequent multi-shot CSI reports.

<FIG> may also describe the fourth alternative in which the base station, using the higher level signalling, has configured the UE with threshold values for the data in the CSI report. In this alternative, the UE may insert, encode and send a first CSI report <NUM> in response to receiving a CSI request. The UE then calculates die CSI values (e.g. RI, PMI, PT1 and CQI) for each DL channel but only inserts reports in sub-frames <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, in which at least one of the calculated CSI values is greater than a maximum threshold value or less than a minimum threshold value. This alternative may be combined with the alternatives shown in <FIG> so that the UE only calculates the CSI values for every Pth sub-frame and may be limited in the number of CSI reports it sends either by the value N or by a deactivating DCI or MAC CE.

<FIG> shows another implementation which does not use higher-level signalling. In this embodiment, the base station configures the UE using the TPC and DM-RS cyclic shift fields. In this embodiment, the base station may configure the UE by sending a DCI having a non-zero valued CSI field, a zero-valued TPC field and a non-zero value in the DM-RS cyclic shift field. In one implementation, die non-zero value in the DM-RS field may represent the period value P so that a periodicity of between <NUM> and <NUM> sub-frames can be specified. After the CSI request is received at <NUM>, the UE calculates, inserts and encodes CSI reports into sub-frames <NUM>, <NUM>, <NUM> and <NUM> with a period of P until a deactivating DCI, having a non-zero CSI field and zero-valued TPC and DM-RS cyclic shift fields, is received at <NUM>.

Claim 1:
An apparatus (<NUM>) of a user equipment, UE (<NUM>), the apparatus (<NUM>) comprising:
an interface (<NUM>); and
processing circuitry (<NUM>) in communication with the interface (<NUM>) and arranged to:
decode a configuration to send multiple channel state information, CSI, reports to a base station (<NUM>), wherein the configuration specifies a CSI reporting periodicity on the physical uplink control channel, PUCCH;
decode a medium access control, MAC, control element, CE, the MAC CE including a request to activate the multiple CSI reports via the PUCCH, each CSI report of the multiple CSI reports describing channel status for a channel between the base station (<NUM>) and the UE (<NUM>);
transmit (<NUM>-<NUM>) the multiple CSI reports in response to the MAC CE;
stop transmitting the multiple CSI reports responsive to receiving a second MAC CE (<NUM>) deactivating the multiple CSI reports;
and
for each of the multiple CSI reports:
generate the respective CSI report according to the configuration;
and
encode the respective CSI report for transmission to the base station (<NUM>) on the PUCCH.