CN109075828B

CN109075828B - Method and apparatus for implementing uplink MIMO

Info

Publication number: CN109075828B
Application number: CN201780026321.0A
Authority: CN
Inventors: 埃科·昂高萨努斯; 麦德·赛弗·拉赫曼; 阿里斯·帕帕萨克拉里欧; 黄文隆
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2016-04-26
Filing date: 2017-04-26
Publication date: 2023-04-28
Anticipated expiration: 2037-04-26
Also published as: EP3449579A2; CN109075828A; WO2017188736A2; CN116346179A; KR102587760B1; EP3449579A4; KR20220156098A; KR20180129875A; WO2017188736A3

Abstract

The present disclosure relates to a pre-fifth generation (5G) or 5G communication system to be provided for supporting higher data rates than fourth generation (4G) communication systems like Long Term Evolution (LTE). Methods and apparatus are provided for implementing uplink Multiple Input Multiple Output (MIMO). A User Equipment (UE) includes a transceiver and a processor operatively connected to the transceiver. The transceiver is configured to receive Uplink (UL) grants for UL transmissions. The processor is configured to decode a precoding information field in Downlink Control Information (DCI) associated with the UL grant. The precoding information field includes at least one Precoding Matrix Indicator (PMI) corresponding to the plurality of precoders. The transceiver is further configured to precode the data stream according to the precoder indicated by the precoding information field and to transmit the precoded data stream on the UL channel.

Description

Method and apparatus for implementing uplink MIMO

Technical Field

In order to meet the increasing demand for wireless data traffic since the deployment of 4G (4 th generation) communication systems, efforts have been made to develop improved 5G (5 th generation) or pre-5G communication systems. Therefore, a 5G or pre-5G communication system is also referred to as a "super 4G network" or a "LTE-after-system".

It is believed that 5G communication systems will be implemented in the millimeter wave (mmWave) frequency band (e.g., the 60GHz frequency band) in order to achieve higher data rates. In order to reduce propagation loss of radio waves and increase transmission distance, a beam forming technique, a massive Multiple Input Multiple Output (MIMO) technique, a full-dimensional MIMO (FD-MIMO) technique, an array antenna technique, an analog beam forming technique, a massive antenna technique are discussed in the 5G communication system.

Further, in the 5G communication system, development is being conducted for system network improvement based on advanced small cellular, cloud Radio Access Network (RAN), ultra dense network, device-to-device (D2D) communication, wireless backhaul, mobile network, cooperative communication, cooperative multipoint (CoMP), reception-side interference cancellation, and the like.

In 5G systems, hybrid FSK and QAM modulation (FQAM) and Sliding Window Superposition Coding (SWSC) as Advanced Code Modulation (ACM), and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access technologies have been developed.

The present disclosure relates generally to methods for implementing uplink Multiple Input Multiple Output (MIMO). These methods may be used when the user equipment is equipped with a plurality of transmit antennas and transmit-receive units.

Background

Wireless communication has been one of the most successful innovations in modern history. As smart phones and other mobile data devices (such as tablet computers, "notepad" computers, netbooks, e-book readers, and machine-type devices) continue to grow in popularity for consumers and businesses, the demand for wireless data traffic has increased rapidly. Improvements in wireless interface efficiency and coverage are critical in order to meet the high growth in mobile data traffic and support new applications and deployments.

The mobile device or user equipment may measure the quality of the downlink channel and report the quality to the base station in order to be able to determine whether various parameters should be adjusted during communication with the mobile device. Existing channel quality reporting processes in wireless communication systems are inadequate for reporting channel state information associated with large two-dimensional array transmission antennas, or antenna array geometries that are generally suitable for accommodating a large number of antenna elements.

Disclosure of Invention

Embodiments of the present disclosure provide methods and apparatus for CSI reporting.

In one embodiment, a User Equipment (UE) is provided. The UE includes a transceiver and a processor operatively connected to the transceiver. The transceiver is configured to receive Uplink (UL) grants for UL transmissions. The processor is configured to decode a precoding information field in Downlink Control Information (DCI) associated with the UL grant. The precoding information field includes at least one Precoding Matrix Indicator (PMI) corresponding to the plurality of precoders. The transceiver is further configured to precode the data stream according to the precoder indicated by the precoding information field and to transmit the precoded data stream on the UL channel.

In another embodiment, a Base Station (BS) is provided. The BS includes a processor and a transceiver operatively connected to the processor. The processor is configured to generate a precoding information field in the DCI and generate a UL grant for UL transmission to the UE. The transceiver is configured to transmit UL grants to the UE via a Downlink (DL) channel. The DCI is associated with a UL grant, and the precoding information field includes at least one PMI corresponding to a plurality of precoders.

In another embodiment, a method for operating a UE is provided. The method includes receiving, by the UE, a UL grant for a UL transmission. The method also includes decoding, by the UE, a precoding information field in the DCI associated with the UL grant, wherein the precoding information field includes at least one PMI corresponding to the plurality of precoders. The method also includes precoding, by the UE, the data stream according to a precoder indicated by the precoding information field. The method also includes transmitting, by the UE, the precoded data stream on the UL channel.

In another embodiment, a method for operating a Base Station (BS) is provided. The method comprises the following steps: generating a precoding information field in Downlink Control Information (DCI); generating an Uplink (UL) grant for UL transmission to a User Equipment (UE); and transmitting an UL grant to the UE via a Downlink (DL) channel, wherein the DCI is associated with the UL grant and the precoding information field includes at least one Precoding Matrix Indicator (PMI) corresponding to the plurality of precoders.

The present disclosure relates to a pre-fifth generation (5G) or 5G communication system to be provided for supporting higher data rates than fourth generation (4G) communication systems like Long Term Evolution (LTE).

Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

Before proceeding with the detailed description that follows, it may be advantageous to define certain words and phrases used throughout this patent document. The term "couple" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate" and derivatives thereof, encompass both direct and indirect communication. The words "include" and "comprise" and derivatives thereof mean inclusion without limitation. The term "or" is inclusive, meaning and/or. The phrase "associated with" and derivatives thereof means including, comprising, being within, interconnected with, containing, being within, being connected to or with the right, being coupled to or with the right, being communicable with, being co-operative with, being interleaved with, being juxtaposed with, being proximate to, being adhered to or with the right, being adhered to, having the right attribute, having a relationship or relationship with …, or the like. The term "controller" means any device, system, or portion thereof that controls at least one operation. Such a device may be implemented as hardware or a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one" when used with a list of items means that different combinations of one or more of the listed items can be used and that only one item in the list may be required. For example, "at least one of A, B and C" includes any one of the following combinations: A. b, C, A and B, A and C, B and C, and a and B and C.

Furthermore, the various functions described below may be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and implemented in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, processes, functions, objects, classes, examples, related data, or a portion thereof adapted for implementation in a suitable computer readable program. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read Only Memory (ROM), random Access Memory (RAM), a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), or any other type of memory. "non-transitory" computer-readable media exclude wired, wireless, optical, or other communication links that transmit transient electrical signals or other signals. Non-transitory computer readable media include media in which data can be permanently stored and media in which data can be stored and later rewritten, such as rewritable optical disks or erasable memory devices.

Definitions for certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art will understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

Drawings

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which like reference numbers indicate like parts throughout the views:

fig. 1 illustrates an exemplary wireless network in accordance with various embodiments of the present disclosure;

fig. 2A and 2B illustrate exemplary wireless transmit paths and wireless receive paths according to various embodiments of the present disclosure;

fig. 3A illustrates an exemplary user device in accordance with various embodiments of the present disclosure;

fig. 3B illustrates an exemplary Base Station (BS) according to various embodiments of the present disclosure;

fig. 4 illustrates an exemplary beamforming architecture in which one CSI-RS port is mapped to a large number of analog controlled antenna elements;

fig. 5 illustrates exemplary operations of dynamic and semi-dynamic precoding transmissions in accordance with an embodiment of the present disclosure;

fig. 6 illustrates an exemplary Downlink (DL) signaling for subband precoding and UE processing for interpreting the precoding information DCI field in accordance with an embodiment of the present disclosure;

Fig. 7 illustrates several exemplary DL signaling schemes for supporting subband precoding in accordance with some embodiments of the present disclosure;

fig. 8 illustrates another exemplary DL signaling scheme for supporting subband precoding according to embodiments of the present disclosure;

fig. 9 shows a flowchart of an example method according to an embodiment of the present disclosure, in which a UE receives a UL grant for UL transmission, the UL grant for UL transmission including precoding information fields associated with a plurality of precoders.

Fig. 10 shows a flowchart of an exemplary method according to an embodiment of the present disclosure, in which a BS generates a precoding information field with at least one PMI for a UE (labeled UE-k).

Detailed Description

Figures 1 through 10, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged wireless communication system.

List of acronyms

2D: two-dimensional

MIMO: multiple input multiple output

SU-MIMO: single user MIMO

MU-MIMO: multi-user MIMO

3GPP: third generation partnership project

LTE: long term evolution

UE: user equipment

eNB: evolved node B or "eNB"

BS: base station

DL: downlink link

UL: uplink channel

CRS: cell specific reference signal

DMRS: demodulation of reference signals

SRS: detecting a reference signal

UE-RS: UE-specific reference signal

CSI-RS: channel state information reference signal

SCID: scrambling identity

MCS: modulation and coding scheme

RE: resource elements

CQI: channel quality information

PMI: precoding matrix indicator

RI: rank indicator

MU-CQI: multi-user CQI

CSI: channel state information

CSI-IM: CSI interference measurement

CoMP: coordinated multipoint

DCI: downlink control information

UCI: uplink control information

PDSCH: physical downlink shared channel

PDCCH: physical downlink control channel

PUSCH: physical uplink shared channel

PUCCH: physical uplink control channel

PRB: physical resource block

RRC: radio resource control

AoA: angle of arrival

AoD: departure angle

The following documents and standard descriptions are incorporated herein by reference as if fully set forth herein: 3GPP Technical Specification (TS) 36.211 version 12.4.0, "E-UTRA, physical channel and modulation" ("reference 1"); 3gpp TS 36.212 release 12.3.0, "E-UTRA, multiplexing and channel coding" ("reference 2"); 3GPP TS 36.213 version 12.4.0, "E-UTRA, physical layer handling" ("reference 3"); 3GPP TS 36.321 version 12.4.0, "E-UTRA, media Access Control (MAC) protocol Specification" ("reference 4"); and 3GPP TS36.331 version 12.4.0, "E-UTRA, radio Resource Control (RRC) protocol Specification" ("reference 5").

Fig. 1 illustrates an exemplary wireless network 100 according to various embodiments of the present disclosure. The embodiment of the wireless network 100 shown in fig. 1 is for illustration only. Other embodiments of wireless network 100 may be used without departing from the scope of this disclosure.

The wireless network 100 includes a Base Station (BS) 101, a BS 102, and a BS 103.BS 101 communicates with BS 102 and BS 103.BS 101 is also in communication with at least one Internet Protocol (IP) network 130, such as the internet, a proprietary IP network, or other data network. Alternative terms such as "eNB" (enhanced node B) or "gNB" (generic node B) may also be used instead of "BS". Other well-known terms may be used in place of "gNB" or "BS", such as "base station" or "access point", depending on the network type. For convenience, the terms "gNB" and "BS" are used in this patent document to refer to the network infrastructure components that provide wireless access to remote terminals. Further, other well-known terms may be used in place of "user equipment" or "UE" such as "mobile station", "subscriber station", "remote terminal", "wireless terminal" or "user device", depending on the type of network. For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses the gNB, whether the UE is a mobile device (such as a mobile phone or a smart phone) or is generally considered to be a stationary device (such as a desktop computer or a vending machine).

The gNB 102 provides wireless broadband access to the network 130 for a first plurality of User Equipment (UEs) within the coverage area 120 of the gNB 102. The first plurality of UEs includes UE 111, which may be located in a Small Business (SB); a UE 112 that may be located in an enterprise organization (E); UE 113, which may be located in a WiFi Hotspot (HS); UE 114, which may be located in a first home (R); a UE 115 that may be located in a second home (R); and UE 116, which may be a mobile device (M) (e.g., a cell phone, wireless notebook computer, wireless PDA, etc.). The gNB 103 provides wireless broadband access to the network 130 for a second plurality of UEs within the coverage area 125 of the gNB 103. The second plurality of UEs includes UE 115 and UE 116. In some implementations, one or more of the gnbs 101-103 can communicate with each other and with UEs 111-116 using 5G, LTE, LTE-A, wiMAX or other advanced wireless communication technology.

The dashed lines illustrate the general extent of

coverage areas

120 and 125, which are shown as approximately circular for purposes of illustration and explanation. It should be clearly understood that the coverage areas associated with the gnbs, such as

coverage areas

120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the gnbs and the variations in the radio environment associated with natural and man-made obstructions.

As described in more detail below, one or more of gNB 101, gNB 102, and gNB 103 transmit measurement reference signals to UEs 111-116, and configure UEs 111-116 for CSI reporting, as described in the embodiments of the disclosure. In various embodiments, one or more of UEs 111-116 receives the transmission scheme or precoding information signaled in the uplink grant and transmits accordingly.

Although fig. 1 illustrates one example of a wireless network 100, various changes may be made to fig. 1. For example, wireless network 100 may include any number of gnbs and any number of UEs in any suitable arrangement. Further, the gNB 101 may communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network 130. Similarly, each of the gnbs 102-103 may communicate directly with the network 130 and provide the UE with direct wireless broadband access to the network 130. Furthermore, gNB 101, gNB 102, and/or gNB 103 may provide access to other or additional external networks (such as external telephone networks or other types of data networks).

Fig. 2A and 2B illustrate exemplary wireless transmit paths and wireless receive paths according to the present disclosure. In the following description, transmit path 200 may be described as being implemented in a gNB (e.g., gNB 102), while receive path 250 may be described as being implemented in a UE (e.g., UE 116). However, it should be understood that the receive path 250 may be implemented in the gNB and the transmit path 200 may be implemented in the UE. In some embodiments, as described in the presently disclosed embodiments, the receive path 250 is configured to receive a transmission scheme or a precoded signal signaled in an uplink grant and transmit accordingly.

The transmit path 200 includes a channel coding and modulation block 205, a serial-to-parallel (S-to-P) block 210, an N-sized Inverse Fast Fourier Transform (IFFT) block 215, a parallel-to-serial (P-to-S) block 220, an add cyclic prefix block 225, and an up-converter (UC) 230. The receive path 250 includes a down-converter (DC) 255, a remove cyclic prefix block 260, a serial-to-parallel (S-to-P) block 265, an N-sized Fast Fourier Transform (FFT) block 270, a parallel-to-serial (P-to-S) block 275, and a channel decoding and demodulation block 280.

In the transmit path 200, a channel coding and modulation block 205 receives a set of information bits, applies coding, such as convolutional, turbo, or low-density parity-check (LDPC) coding, and modulates input bits, such as with Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM), to generate a sequence of frequency-domain modulation symbols. Serial-to-parallel block 210 transforms (e.g., demultiplexes) the serial modulated symbols into parallel data to generate N parallel symbol streams, where N is the IFFT/FFT size used in the gNB 102 and UE 116. An N-sized IFFT block 215 performs an IFFT operation on the N parallel symbol streams to generate a time-domain output signal. Parallel-to-serial block 220 transforms (e.g., multiplexes) the parallel time-domain output symbols from the N-sized IFFT block 215 to generate a serial time-domain signal. The "Add cyclic prefix" block 225 inserts a cyclic prefix into the time domain signal. Up-converter 230 modulates (up-converts) the output of "add cyclic prefix" block 225 to RF frequency for transmission over a wireless channel. The signal may also be filtered at baseband before being converted to RF frequencies.

The transmitted RF signals arrive at the UE 116 from the gNB 102 after passing through the wireless channel, and operations reverse to those at the gNB 102 are performed at the UE 116. The down-converter 255 down-converts the received signal to baseband frequency and the remove cyclic prefix block 260 removes the cyclic prefix to generate a serial time domain baseband signal. Serial-to-parallel block 265 converts the time-domain baseband signal into a parallel time-domain signal. The N-sized FFT block 270 performs an FFT algorithm to generate N parallel frequency domain signals. Parallel-to-serial block 275 converts the parallel frequency domain signals into a sequence of modulated data symbols. The channel decoding and demodulation block 280 demodulates and decodes the modulation symbols to recover the original input data stream.

As described in more detail below, transmit path 200 or receive path 250 may perform signaling for CSI reporting. Each of the gnbs 101 to 103 may implement a transmission path 200 that simulates transmitting to the UEs 111 to 116 in the downlink, and may implement a reception path 250 that simulates receiving from the UEs 111 to 116 in the uplink. Similarly, each of UEs 111-116 may implement a transmit path 200 for transmitting to gnbs 101-103 in the uplink, and may implement a receive path 250 for receiving from gnbs 101-103 in the downlink.

Each of the components in fig. 2A and 2B may be implemented using hardware alone or using a combination of hardware and software/firmware. As a specific example, at least some of the components in fig. 2A and 2B may be implemented in software, while other components may be implemented in configurable hardware or a mixture of software and configurable hardware. For example, FFT block 270 and IFFT block 215 may be implemented as configurable software algorithms, wherein the value of N size may vary depending on the implementation.

Further, although described as using an FFT and an IFFT, this is by way of example only and should not be construed as limiting the scope of the present disclosure. Other types of transforms may be used, such as Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions. It should be appreciated that for DFT and IDFT functions, the value of the variable N may be any integer (such as 1, 2, 3, 4, etc.), while for FFT and IFFT functions, the value of the variable N may be any integer that is a power of 2 (such as 1, 2, 4, 8, 16, etc.).

Although fig. 2A and 2B show examples of a wireless transmission path and a wireless reception path, various changes may be made to fig. 2A and 2B. For example, the various components in fig. 2A and 2B may be combined, further subdivided, or omitted, and additional components may be added according to particular needs. Also, fig. 2A and 2B are intended to illustrate examples of the types of transmit and receive paths that may be used in a wireless network. Other suitable architectures may be used to support wireless communications in a wireless network.

Fig. 3A illustrates an exemplary UE 116 according to the present disclosure. The embodiment of UE 116 shown in fig. 3A is for illustration only, and UEs 111-115 of fig. 1 may have the same or similar configuration. However, the UE has a variety of configurations, and fig. 3A does not limit the scope of the present disclosure to any particular implementation of the UE.

UE 116 includes an antenna 305, a Radio Frequency (RF) transceiver 310, transmit (TX) processing circuitry 315, a microphone 320, and Receive (RX) processing circuitry 325.UE 116 further includes speaker 330, processor 340, input/output (I/O) Interface (IF) 345, input 350, display 355, and memory 360. Memory 360 includes an Operating System (OS) program 361 and one or more applications 362.

RF transceiver 310 receives incoming RF signals from antenna 305 that are transmitted by the gNB of network 100. The RF transceiver 310 down-converts the incoming RF signal to generate an Intermediate Frequency (IF) or baseband signal. The IF or baseband signal is sent to RX processing circuit 325, and RX processing circuit 325 generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. RX processing circuit 325 sends the processed baseband signal to speaker 330 (e.g., for voice data) or to processor 340 for further processing (e.g., for web browsing data).

TX processing circuitry 315 receives analog or digital voice data from microphone 320 or other outgoing baseband data (such as network data, email, or interactive video game data) from processor 340. TX processing circuitry 315 encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or IF signal. RF transceiver 310 receives outgoing processed baseband or IF signals from TX processing circuitry 315 and up-converts the baseband or IF signals to RF signals for transmission via antenna 305.

Processor 340 may include one or more processors or other processing devices and execute OS program 361 stored in memory 360 to control the overall operation of UE 116. For example, processor 340 may control the reception of forward channel signals and the transmission of reverse channel signals by RF transceiver 310, RX processing circuit 325, and TX processing circuit 315 in accordance with well-known principles. In some embodiments, processor 340 includes at least one microprocessor or microcontroller.

As described in the presently disclosed embodiments, the processor 340 is also capable of executing other processes and programs residing in the memory 360, such as operations for CQI measurement and reporting for the system described in the presently disclosed embodiments. Processor 340 may move data into or out of memory 360 as needed to perform the processing. In some implementations, the processor 340 is configured to execute the application 362 based on the OS program 361 or in response to a signal received from the gNB or operator. Processor 340 is also coupled to I/O interface 345, I/O interface 345 providing UE 116 with the ability to connect to other devices, such as laptop computers and handheld computers. I/O interface 345 is the communication path between these accessories and processor 340.

Processor 340 is also coupled to input 350 (e.g., keyboard, touch screen, buttons, etc.) and display 355. The operator of UE 116 may use input 350 to input data into UE 116. Display 355 may be a liquid crystal display or other display capable of presenting text and/or at least limited graphics, such as from a website.

Memory 360 is coupled to processor 340. A portion of memory 360 may include Random Access Memory (RAM) and another portion of memory 360 may include flash memory or other Read Only Memory (ROM).

As described in more detail below, UE 116 may perform signaling and calculations for CSI reporting. Although fig. 3A shows one example of UE 116, various changes may be made to fig. 3A. For example, the various components in FIG. 3A may be combined, further subdivided, or omitted, and additional components may be added according to particular needs. As a particular example, the processor 340 may be divided into multiple processors, such as one or more Central Processing Units (CPUs) and one or more Graphics Processing Units (GPUs). Moreover, while fig. 3A shows the UE 116 configured as a mobile phone or smart phone, the UE may be configured to operate as other types of mobile or stationary devices.

Fig. 3B illustrates an exemplary gNB 102 in accordance with the present disclosure. The embodiment of the gNB 102 shown in FIG. 3B is for illustration only, and other gNBs of FIG. 1 may have the same or similar configuration. However, the gNB has a variety of configurations, and fig. 3B does not limit the scope of the disclosure to any particular implementation of the gNB. The gNB 101 and the gNB 103 may include the same or similar structures as the gNB 102.

As shown in fig. 3B, the gNB 102 includes a plurality of antennas 370a through 370n, a plurality of RF transceivers 372a through 372n, transmit (TX) processing circuitry 374, and Receive (RX) processing circuitry 376. In certain embodiments, one or more of the plurality of antennas 370a through 370n comprises a 2D antenna array. The gNB 102 also includes a controller/processor 378, a memory 380, and a backhaul or network interface 382.

RF transceivers 372 a-372 n receive incoming RF signals from antennas 370 a-370 n, such as signals transmitted by a UE or other gNB. The RF transceivers 372 a-372 n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signal is sent to RX processing circuit 376, and RX processing circuit 376 generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuit 376 sends the processed baseband signals to a controller/processor 378 for further processing.

TX processing circuitry 374 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from controller/processor 378. TX processing circuitry 374 encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or IF signal. RF transceivers 372a through 372n receive outgoing processed baseband or IF signals from TX processing circuitry 374 and up-convert the baseband or IF signals to RF signals for transmission via antennas 370a through 370 n.

The controller/processor 378 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, controller/processor 378 may control the reception of forward channel signals and the transmission of reverse channel signals by RF transceivers 372 a-372 n, RX processing circuit 376, and TX processing circuit 374 in accordance with well-known principles. The controller/processor 378 may also support additional functions, such as higher-level wireless communication functions. In some embodiments, controller/processor 378 includes at least one microprocessor or microcontroller.

Controller/processor 378 is also capable of executing programs and other processes residing in memory 380, such as an OS. As described in the embodiments of the present disclosure, controller/processor 378 is also capable of supporting channel quality measurements and reporting for systems having 2D antenna arrays. In some implementations, the controller/processor 378 supports communication between entities, such as web RTCs. Controller/processor 378 may move data into or out of memory 380 as needed to perform the processes.

The controller/processor 378 is also coupled to a backhaul or network interface 382. The backhaul or network interface 382 allows the gNB 102 to communicate with other devices or systems through a backhaul connection or through a network. The interface 382 may support communication over any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as supporting 5G or new radio access technologies or NR, LTE, or one of LTE-a), the interface 382 may allow the gNB 102 to communicate with other gnbs over a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 382 may allow the gNB 102 to communicate with a larger network (e.g., the Internet) through a wired or wireless local area network or through a wired or wireless connection. The interface 382 includes any suitable structure that supports communication over a wired or wireless connection, such as an ethernet or RF transceiver.

Memory 380 is coupled to controller/processor 378. A portion of memory 380 may include RAM and another portion of memory 380 may include flash memory or other ROM. In some embodiments, a plurality of instructions, such as BIS algorithms, are stored in the memory. The plurality of instructions are configured to cause the controller/processor 378 to perform BIS processing and to decode the received signal after subtracting the at least one interfering signal determined by the BIS algorithm.

As described in more detail below, the transmit path and the receive path of the gNB 102 (implemented using RF transceivers 372 a-372 n, TX processing circuitry 374, and/or RX processing circuitry 376) perform configuration and signaling for CSI reporting.

Although fig. 3B shows one example of the gNB 102, various changes may be made to fig. 3B. For example, the gNB 102 may include any number of each of the components shown in FIG. 3A. As a particular example, an access point may include multiple interfaces 382 and the controller/processor 378 may support routing functions to route data between different network addresses. As another particular example, while shown as including a single instance of TX processing circuitry 374 and a single instance of RX processing circuitry 376, the gNB 102 may include multiple instances of each (e.g., one for each RF transceiver).

Rel.13lte supports up to 16 CSI-RS antenna ports that enable the gNB to be equipped with a large number of antenna elements (such as 64 or 128). In this case, multiple antenna elements are mapped onto one CSI-RS port. Furthermore, up to 32 CSI-RS ports will be supported in rel.14lte. For next generation cellular systems like 5G, it is expected that the maximum number of CSI-RS ports remains more or less the same.

For the millimeter wave band, while the number of antenna elements may be greater for a given form factor, as shown in embodiment 400 of fig. 4, the number of CSI-RS ports, which may correspond to the number of digital pre-coding ports, tends to be limited due to hardware limitations (e.g., the feasibility of installing a large number of ADCs/DACs at millimeter wave frequencies). In this case, one CSI-RS port is mapped onto a large number of antenna elements controllable by a set of analog phase shifters 401. Then, one CSI-RS port may correspond to one sub-array that generates a narrow analog beam by analog beamforming 405. The analog beam may be configured to sweep a wider range of angles by changing the phase shifter sets over a symbol or sub-frame (420). The number of subarrays (equal to the number of RF chains) and the number of CSI-RS ports N _CSI-PORT (N _CSI-port ) The same applies. Digital beamforming unit 410 spans N _CSI-PORT The analog beams perform linear combining to further increase the precoding gain. Although the analog beams are wideband (and thus not frequency selective), the digital precoding may vary over frequency subbands or resource blocks.

To achieve digital precoding, efficient design of CSI-RS is an important factor. To this end, three types of CSI reporting mechanisms corresponding to three types of CSI-RS measurement behaviors are supported in rel.13lte: 1) a "CLASS a (CLASS a)" CSI report corresponding to a non-precoded CSI-RS, 2) a "CLASS B (CLASS B)" report having k=1 CSI-RS resources corresponding to a UE-specific beamformed CSI-RS, 3) a "CLASS B (CLASS B)" report having K >1 CSI-RS resources corresponding to a cell-specific beamformed CSI-RS. For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping between CSI-RS ports and TXRUs is utilized. Here, the different CSI-RS ports have the same wide beamwidth and direction, and are therefore typically cell-wide coverage. For beamformed CSI-RS, a (cell-specific or UE-specific) beamforming operation is applied to non-zero power (NZP) CSI-RS resources (which include multiple ports). Here, the CSI-RS ports have a narrow beam width (at least at a given time/frequency) and thus do not have cell width coverage, and at least some CSI-RS port resource combinations have different beam directions (at least from the perspective of the gNB).

In a scenario where DL long-term channel statistics can be measured by the UL signal at the serving gNB, UE-specific BF CSI-RS can be easily used. This is generally possible when the UL-DL duplex distance is sufficiently small. However, when this condition is not met, some UE feedback is used for the gNB to obtain an estimate of DL long-term channel statistics (or any of its representations). To facilitate this process, a first BF CSI-RS is transmitted with a period T1 (ms) and a second NP CSI-RS is transmitted with a period T2 (ms), where T1 is less than or equal to T2. This scheme is called hybrid CSI-RS. The implementation of hybrid CSI-RS depends largely on the definition of CSI processing and NZP CSI-RS resources.

In rel.10lte, a codebook-based transmission scheme is used to support UL SU-MIMO transmission. That is, the UL grant (including DCI format 4) includes a single PMI field (along with the RI) that indicates that a single precoding vector or matrix (from a predefined codebook) should be used by the UE for the scheduled UL transmission. Thus, when multiple PRBs are allocated to a UE, a single precoding matrix indicated by the PMI means to utilize wideband UL precoding. This is clearly suboptimal, although it is simple, because typical UL channels are frequency selective and UEs are frequency scheduled for transmission using multiple PRBs.

Yet another disadvantage of rel.10lte UL SU-MIMO is the lack of support for scenarios where accurate UL-CSI cannot be obtained at the gNB (which is required for correct operation of codebook-based transmissions). This situation may occur in the scenario of a UE with high mobility or in the scenario of bursty inter-cell interference in a cell with poor isolation.

Therefore, new components need to be designed to achieve more efficient support for UL MIMO for the following reasons. First, it is desirable to support frequency selective (or subband) precoding for UL MIMO as much as possible. Second, UL MIMO should provide competitive performance even when accurate UL-CSI is not available at the gNB. Furthermore, the proposed UL MIMO solution should be able to exploit UL-DL reciprocity, where the UE uses CSI-RS to provide UL-CSI estimation for TDD scenarios.

In the present disclosure, unless otherwise specified, the terms PMI (precoding matrix indicator) and TPMI (transmit PMI) are used interchangeably to indicate an UL-related DCI field that indicates an allocated precoder or precoder group used by a UE for scheduled UL transmissions. Likewise, unless otherwise indicated, the terms RI (rank indicator) and TRI (transmission RI) are used interchangeably to indicate a UL-related DCI field indicating the number of allocated layers that a UE uses for scheduled UL transmissions.

The present disclosure includes at least four components for implementing UL MIMO. The first component includes a method for configuring a precoded UL transmission. The second component includes an embodiment for supporting UL frequency selective precoding. The third component includes a method for implementing reciprocity-based UL MIMO transmission. The fourth component includes a method for UL transmission having two waveforms. The names or terms used to represent functionality are exemplary and may be replaced with other names or labels without changing the essence of the embodiment.

For the first component (i.e., configuring the precoded UL transmissions), one exemplary embodiment for facilitating operation in various scenarios, dynamic and semi-dynamic beamforming may be described as follows. In one embodiment, dynamic beamforming is particularly applicable when accurate UL-CSI is available at the gNB or UE (e.g., low UE speed and good cell isolation or inter-cell interference coordination). In this case, since accurate direction information is accessible, the UE may transmit data through a narrow directional beam. For FDD, the gNB may signal the UE with beamforming or precoding vector/matrix (or vectors/matrices) selection via DL control channels (e.g., UL grant). Upon receiving such precoding information, the UE should send the requested UL data to the gNB using an associated precoder or beamformer. The precoding information is dynamically updated by the gNB.

To support dynamic beamforming, codebook-based MIMO transmission may be used, where the UL grant (including the associated DCI) includes a single precoding information (PMI) field (along with RI). The PMI indicates a single precoding matrix to be used by the UE for the scheduled UL transmission. Thus, one precoder or beamforming is applied to all scheduled PRBs of the UE.

Semi-dynamic beamforming is particularly useful when UL-CSI quality is compromised at the gNB or UE (e.g., high UE speed and poor cell isolation leading to inter-cell interference of bursts known as the flash effect). In this case, it is more advantageous for the gNB to transmit data over a set of directional beams, since the UE can only indicate approximate direction information (or range). For this purpose, a precoder (beam) may be employed that cycles within a set of beams in the time (over OFDM symbols) or frequency (over REs, RBs, or a set of RBs) domain. Such approximate direction information may be signaled to the UE via a DL control channel (e.g., UL grant). Such information may be a type of long-term precoding information or an indicator of a subset of precoders.

For semi-dynamic beamforming, a set of multiple precoders is used in combination with a predetermined cyclic pattern (or set of cyclic patterns). A set of cyclic patterns or precoders may be specified and signaled to the UE via UL grant. The PMI field for dynamic beamforming may be extended to support semi-dynamic beamforming via precoder cycling. For rank-1 (one layer) transmission, such semi-dynamic beamforming may be cascaded with transmission diversity such as SFBC or SFBC-FSTD applied to two or four beams, where the number of beams may be configured as the number of UL antenna ports.

Fig. 5 depicts an example operation 500 in which UE1 502 and UE2 503 are connected with a gNB 501. The gNB schedules UL transmissions for UE1 via UL grant 1 and for UE2 via UL grant 2. After receiving and successfully decoding UL grant 1, which contains a grant for UE1 to transmit data using dynamic beamforming, UE1 transmits on the UL using dynamic beamforming. That is, UE1 precodes its data so that the data is transmitted via one narrow directional beam. The precoder used by UE1 is signaled via the PMI field in UL grant 1. After receiving and successfully decoding UL grant 2, which contains a grant for UE2 to transmit data using semi-dynamic beamforming, UE1 transmits on the UL using semi-dynamic beamforming. That is, UE2 precodes its data such that the data is transmitted via multiple directional beams that cycle the four beams in time (on OFDM symbols), frequency (on REs or RBs), or both time and frequency. In fig. 5, four spatially overlapping beams are shown for illustrative purposes. The set of precoders used by UE1 or the use of four beams in a cyclic manner is signaled via the PMI field in UL grant 2.

In this disclosure, the terms "dynamic beamforming" and "semi-dynamic beamforming" are used for illustrative purposes. Other terms may also be used to refer to the same method and/or function. For example, terms such as "transmission scheme 1 or a" and "transmission scheme 2 or B" -or "transmission mode 1" and "transmission mode 2" may be used to represent two transmission methods, respectively. These two transmission schemes may also be used with other transmission schemes.

To configure the UE interchangeably with dynamic or semi-dynamic beamforming as shown in fig. 5, several alternative implementations are possible.

In a first embodiment, the UE is semi-statically configured with dynamic or semi-dynamic beamforming via higher layer (e.g., RRC) signaling. An example of this embodiment is to perform a transmission scheme or a transmission mode configuration via at least one RRC parameter. In this case, the value of the RRC parameter indicates whether the UE is configured with dynamic beamforming or semi-dynamic beamforming.

In this first embodiment, the PMI field that is part of the DCI in the UL grant (mentioned earlier) may be used for both dynamic and semi-dynamic beamforming. The PMI field may be configured to signal different hypotheses depending on whether the UE is configured with dynamic beamforming or semi-dynamic beamforming. When the UE is configured with dynamic beamforming, the PMI field indicates the precoding matrix or vector that should be used by the UE for licensed UL data transmission. When the UE is configured with semi-dynamic beamforming, the PMI field may indicate the selection of a precoding matrix or set of vectors that should be used by the UE for licensed UL data transmission.

An example is given in table 1, in which a set of MO-length time-oversampled DFT vectors is used as a set of possible rank-1 precoders for M antenna ports. Thus, (OM-1) sets of precoding vectors are available. As an example, the RRC or higher layer parameter indicating whether the UE is configured with dynamic beamforming or semi-dynamic beamforming is beamformamine scheme. When the parameter beamformamingscheme indicates "dynamic" (i.e., dynamic beamforming), pmi=i indicates that the UE is requested (should) to use precoder v _i For UL data transmission. When the parameter beamformamingscheme indicates "semi-dynamic" (i.e., semi-dynamic beamforming), pmi=i indicates that the requesting UE (should) use precoder set G _i (which includes B consecutive precoder groups) for UL data transmission. Alternatively, if the UL channel angle spread is large, a set of B non-consecutive precoders can also be used.

Exemplary PMI Table of embodiment 1

[ Table 1 ]

In a second embodiment, the UE is dynamically configured with dynamic or semi-dynamic beamforming via UL grants transmitted on DL control channels.

One example of this second embodiment is to use one DCI parameter to instruct the UE to indicate the selection of a transmission scheme or mode (dynamic or semi-dynamic) that should be used by the UE for licensed UL data transmission. In this example, the PMI field that is part of the DCI in the UL grant may be used for both dynamic and semi-dynamic beamforming. Depending on the value of the DCI parameter (i.e., whether the UE is configured with dynamic or semi-dynamic beamforming), a PMI field is also required. When the UE is configured with dynamic beamforming, the PMI field indicates the precoding matrix or vector that should be used by the UE for licensed UL data transmission. When the UE is configured with semi-dynamic beamforming, the PMI field may indicate the selection of a precoding matrix or set of vectors that should be used by the UE for licensed UL data transmission. This example may be described similarly to table 1. In this case, however, the higher layer parameter beamformamine scheme may be replaced with a DCI field beamformamine scheme having a value of 0 (representing, for example, semi-dynamic beamforming) or a value of 1 (representing, for example, dynamic beamforming).

Another example of this second embodiment is to use only one PMI field as part of the DCI in the UL grant. In this case, consider a total of N associated with the PMI field of the B bits _H A possible hypothesis (where N _H ≤2 ^B )，N _H Some N of the hypotheses _H，d May be utilized to indicate precoder selections for dynamic beamforming, while the remainder (N _H，sd ＝N _H -N _H，d A hypothesis) may be utilized to indicate the selected precoder set for semi-dynamic beamforming. This example may be described in table 2. In comparison to table 1, table 2 combines hypotheses from dynamic and semi-dynamic beamforming into one set indicated by the PMI field. For this example, the number of hypotheses associated with the PMI field is twice the number associated with the first example of the second embodiment and the PMI field in the first embodiment.

Exemplary PMI Table of embodiment 2 (second example)

[ Table 2 ]

Alternatively, a two-dimensional precoder or codebook (particularly geometrically related to a two-dimensional or rectangular array) may be utilized. In this case, the precoder may correspond to a pair of indexes (m ₁ ，m ₂ ) While each index represents one of two dimensions. An exemplary rank-1 precoder modeled as described above may be described in equation 3 (where v _i And G _i Defined in equation 2). Here, M ₁ And M ₂ Representing the number of ports in the first and second dimensions, respectively. Likewise, O ₁ And O ₂ Representing the oversampling factors in the first and second dimensions, respectively.

Alternatively, a one-dimensional precoder or codebook designed for dual polarized array configuration may also be utilized. In this case, a precoder having two identical parts (each part associated with one polarization group) and co-phased between the two polarization groups may be used. The exemplary one-dimensional 2M port (each of the two polarization groups including M ports) rank-1 precoder modeled as described above may be described in equation 4. Here, K possible co-phase values are used.

m＝(K-1)i+k

Alternatively, a two-dimensional precoder or codebook designed for dual polarized array configuration may also be utilized. Simulated as the exemplary two-dimensional 2M described above ₁ M ₂ Port (including M ₁ M ₂ Each of the two polarization groups of the ports) rank-1 precoder can be described in equation 5. Can be combined with three indexes m constituting a single PMI ₁ ，m ₂ K similarly define the beam group.

With any of the codebook options described above, DL signaling implementations that support switching between dynamic beamforming and semi-dynamic beamforming are applicable and can be extended in a direct forward manner (as each precoder or codebook corresponds to a single PMI).

For the second component (i.e., supporting UL frequency selective precoding), in the above-described embodiments with respect to the first component, a single precoder is indicated to the UE for UL transmission. Thus, for a single allocation, the same precoder applies to all allocated RBs. Optionally, subband precoding may also be supported by signaling one PMI per subband via UL grant, where one subband may include multiple consecutive RBs. In this case, the DCI field containing precoding information includes a plurality of PMIs, each of which is associated with one subband and indicates selection of a precoder from a predetermined codebook.

Fig. 6 shows exemplary DL signaling for subband precoding and UE processing to explain the inclusion of N _PMI Precoding information DCI fields of each PMI (each associated with one subband). Quantity N of PMIs _PMI Subband size P with RB _SUBBAND (P _Sub-band ) Interdependence. For a given UL resource allocation span (RA in number of RBs _RB Expressed), the number of PMIs can be obtained as follows:

thus, for a given UE resource allocation, the number of PMIs is not directly dependent on the number of RBs allocated to the UE, as UL resource allocation may include multiple consecutive RBs (as shown in 601) or clustered RBs (as shown in 602). Instead, it depends on being within the associated UE resource allocation The number of RBs starting from the lowest indexed RB to the highest indexed RB. Representing the RBs with the lowest index and the RBs with the highest index as RBs respectively _low (RB _{Low and low} ) And RB (RB) _high (RB _{High height} )，

Optionally, in RA _RB，i In case of the number of RBs in the ith cluster +.>

The two examples given in fig. 6 represent a continuous resource allocation (601) and a clustered resource allocation (602). Here, P is used for illustrative purposes _SUBBAND =4. Although the total number of RBs allocated in 602 is smaller than that in 601, the total number of subbands, and thus the number of PMIs +.>

Is the same because the dl allocation span is the same for 601 and 602.

As shown in fig. 7, there are several DL signaling implementations for supporting subband precoding. The following examples are different in several aspects, such as whether the associated DCI payload size is fixed or varies with the number of subbands corresponding to the allocated RBs (and thus the number of subband PMIs), whether all PMI components are included in the DCI or whether at least some PMI components are signaled outside the DCI (or primary DCI), and/or whether the number of subbands corresponding to the allocated RBs (and thus the number of subband PMIs) is fixed or varies according to UL resource allocation. When the number of subband PMIs is fixed, PMI granularity (subband size) varies according to UL resource allocation. In contrast, when the PMI granularity (subband size) is fixed, the number of subband PMIs varies according to UL resource allocation.

In the first embodiment 1, as shown by DCI 710, a method including N is used _PMI The length-variable precoding information DCI fields 711 and 712 of each PMI (each associated with one subband). In this case, the subband size (number of RBs per subband) is fixed. PMI (PMI)Number N _PMI Depending on the allocation size and the location of the allocated RBs (e.g., whether the allocated PRBs are contiguous or clustered). Thus, the size of the DCI associated with the UL grant is also variable (depending on the number of subbands). This increases the number of blind decoding attempts at the UE. As shown by DCI 710 of fig. 7, the length of precoding information DCI fields 711 and 712 is scaled according to the number of PMIs inferred from the resource allocation information, where DCI field 712 represents resource allocation requiring more PMIs than DCI field 711 (as is the case where DCI field 712 is allocated more RBs than DCI field 711).

In the second embodiment 2, as shown by DCI 720, a method is used that includes at least precoding information (N _PMI PMI) second (or second level) DL control information. In this case, the subband size (number of RBs per subband) is fixed. The location and size of the precoding information may be made in accordance with the resource allocation indicated in the associated UL grant. In this case, the UE first receives UL grant and decodes DCI field indicating resource allocation. After decoding the resource allocation information, the UE decodes the second DL control information including only precoding information. The precoding information indicates a precoder used by the UE for each RB (subband) set and thus for each RB allocated to the UE. Comprising N _PMI The length precoding information DCI field of the PMI is variable and may be inferred from resource allocation information from the first DL control information. Therefore, the number of blind decoding attempts associated with the first DL control information is not increased.

In this embodiment, the first DL control information may be transmitted via an L1 DL control channel (simulated as LTE PDCCH or ePDCCH) using a C-RNTI or UE ID. The second DL control information may be transmitted separately from the first DL control information, wherein transmission parameters such as its location (in time and/or frequency domain) and/or payload size and/or MCS may be inferred implicitly from the first DL control information (e.g., from the C-RNTI and/or some other UE specific parameters), or explicitly (indicated as DCI fields in the first DL control information). For the second DL control information, the C-RNTI or UE ID may or may not be used. As shown by DCI 720 of fig. 7, the length of the precoding information DCI field is scaled according to the number of subband PMIs inferred from the resource allocation information, where DCI field 722 represents a resource allocation requiring more PMIs than DCI field 721 (as is the case where DCI field 722 is allocated more RBs than DCI field 721). However, unlike the first embodiment, as shown by the DCI 710, the length of the first DL control information including the resource allocation information remains the same, while the length of the second DL control information varies according to the number of required subband PMIs.

The second DL control information may be sent via an L1 DL control channel (e.g., emulated as LTE PDCCH or ePDCCH-thus may be perceived as second-level DCI), or as part of a resource/channel for DL data transmission (e.g., emulated as LTE PDSCH). It may be located in the same slot/subframe as the slot/subframe in which the DCI (or first-level DCI, and thus UL grant) is transmitted, or in a different slot/subframe than it. Whether the second DL control information is transmitted in the form of a second-level DCI or DL data channel transmission (simulated as LTE PDSCH), a CRC may be appended to its information bits to facilitate error detection at the UE.

In the third embodiment 3, as shown by DCI 730, a fixed number N including PMIs is used _PMI >1 (each associated with one subband) a fixed length precoding information DCI field 731. Thus, only a single N is allowed _PMI Values. In this case, the subband size (number of RBs per subband) may be variable depending on the resource allocation (allocation size and location of allocated RBs).

For example, in N _PMI In the case of=2, only two PMIs (thus, two separate precoders) may be allocated to the UE. The first PMI indicates a precoder associated with a first subset of allocated RBs and the second PMI indicates a precoder associated with a second subset of allocated RBs, wherein the second subset is different from the first subset-wherein the first subset and the second subset are combined together to form all RBs allocated to the UE. Thus, the number of allocated RBs for each of the two subsets is variable (depending on the resource allocation). Thus, the size of DCI associated with UL grant is fixed and the number of RBs associated with each of two PMIs is variable . In this case, the number of blind decoding attempts associated with the first DL control information is not increased. As shown by DCI 730 of fig. 7, the length of the precoding information DCI field remains the same because a fixed number of PMIs are used for any resource allocation (i.e., the number of allocated RBs and/or the location of allocated RBs).

For the third embodiment, several sub-embodiments related to the interpretation of each PMI and associated subband size may be described as follows.

In a first sub-embodiment, with N _PMI The set/subset of each associated RB in a subband varies with the resource allocation (i.e., the number of allocated RBs and/or the location of the allocated RBs). However, for a given/fixed resource allocation, and N _PMI The set/subset of each associated RB in a subband is fixed, predetermined, or configured via higher layer signaling. This may be shown, for example, in fig. 6. That is, for a given number and/or location of RBs indicated in the UL Resource Allocation (RA) field, each sub-band constitutes the same number of PRBs and/or subset of PRBs. Thus, no additional indication is required in the associated UL related DCI or via any other DL signaling mechanism.

In a second sub-embodiment, the index of the ith PMI (PMI _i Wherein i=0, 1, N _PMI -1) associated subbands and thus dynamically signaled via UL-related DCI. In this case, only signaling (N _PMI -1) subbands of PMI, since the subbands for one remaining PMI can be derived from the RA field and (N) _PMI -1) the remaining subbands out of the subbands. Thus, in addition to N _PMI Outside of PMI/TPMI, (N) _PMI 1) additional fields (each of the additional fields indicates and (N) _PMI -1) PMI-associated subbands) via UL-related DCI signaling. For example, in N _PMI In case of=2, one additional subband indicator field (for the first PMI or the second PMI) is signaled via UL-related DCI. In a variant of this sub-embodiment, one of the two PMIs (denoted PMI _SB,1 ) A precoder may be indicated for only RBs indicated in the additional subband indicator field (e.g., interpreted as simulated as'The best-M "subband, where the value of M may be dynamically signaled as part of an additional subband indicator field, either via MAC CE, or semi-statically configured via higher layer signaling), while another PMI (denoted PMI _SB,2 ) A wideband precoder may be indicated that is available for all allocated RBs (indicated in the resource allocation DCI field). In another variation of this sub-embodiment, one of the two PMIs (denoted PMI _SB,1 ) A precoder may be indicated for RBs indicated only in the additional subband indicator field (e.g., interpreted as being modeled as a "best-M" subband, where the value of M may be dynamically signaled as part of the additional subband indicator field or semi-statically configured via MAC CE or via higher layer signaling), while another PMI (denoted PMI _SB,2 ) The precoder for the remaining allocated RBs (indicated in the resource allocation DCI field) may be indicated.

To avoid any change in DCI size that may increase the number of UE blind decodes of DL control signaling, the size of the additional subband indicator field may be fixed or configured via higher layer signaling. Thus, the number of hypotheses (or, in addition, the set of hypotheses) associated with the subband indicator field may be fixed or configured via higher layer signaling. For example, in order to be used for PMI _SB,2 The number of subband hypotheses to maintain to a maximum N _HYP When N _RB When a number of RBs are allocated to a UE (as indicated in the resource allocation DCI field), the number of possible subbands (N _RB A subset of RBs) may be fixed or higher layer configured not to exceed N _HYP . If each of these possible subbands has the same size in terms of the number of RBs and the RBs within each subset are as continuous as possible, each of the possible subbands may approximately include

And RB.

In fourth embodiment 4, the precoding information DCI field may include the number of PMIs N _PMI Maximum possible value of K. This embodiment can be regarded as an intermediate zone between embodiment 1 and embodiment 3. In this case, the subband size (number of RBs per subbandAmount) may be variable depending on the resource allocation (allocation size and location of allocated RBs). For example, at k=2 and N _PMI In case of e {1,2}, the precoding information DCI field may contain 1 PMI or 2 PMIs. When the precoding information DCI field contains 1 PMI, the UE should use the precoder indicated by the PMI for all its allocated RBs. When the precoding information DCI field contains 2 PMIs, the first PMI indicates a precoder associated with a first subset of allocated RBs and the second PMI indicates a precoder associated with a second subset of allocated RBs, wherein the second subset is different from the first subset-wherein the first subset and the second subset are combined together to form all RBs allocated to the UE. Thus, the number of allocated RBs for each of the two subsets is variable (depending on the resource allocation).

Thus, the size of the DCI associated with the UL grant is variable (may be one of two possible sizes) and the number of RBs associated with the PMI is variable. This increases the number of blind decoding attempts at the UE, but only by a factor of 2. Except that there are only two possible lengths of precoding information (with N _PMI Associated with the two values of (c), embodiment 4 may be shown in a similar manner as DCI 710 of fig. 7.

For any of the above-described exemplary embodiments for supporting subband precoding, particularly for embodiment 2 (DCI 720 of fig. 7) in which second DL control information comprising a subband PMI is used, there may be an additional assumption in the DCI (or first-level DCI) that indicates that the UE may assume precoding information (including PMI, wideband component or subband component) of previous (or most recent) signaling for licensed UL transmission. The assumption may also indicate that the same precoder (wideband and/or subband) may be used that is signaled in the previously (or most recently) licensed UL transmission.

Several options for signaling this additional assumption are possible. First, the assumption may be associated with one code point of any other existing UL-related DCI field. For example, when precoding information is not included in DCI (or first-level DCI), this is relevant. Some example DCI fields include resource allocation, a DCI field indicating a transmission scheme, or UL DMRS information. Second, a dedicated 1-bit DCI field indicating whether second DL control information including precoding information (e.g., subband PMI) exists. Further, when a dual-stage codebook (described later in this disclosure) is used, a wideband (first-stage) PMI component may be included in DCI (or first-stage DCI) and signaled as a first PMI DCI field. In this case, the additional hypothesis may include one code point that is the first PMI DCI field.

Thus, when this additional hypothesis is detected at the UE, the UE does not attempt to decode the second DL control information comprising the subband PMI, and assumes the previous (most recent) signaling and received precoding information. This scheme contributes to DL control consumption savings because the second DL control information (which may include a subband PMI) is not signaled, for example, when the gNB/network appears not to need to change UL precoder.

A variation of embodiment 2 (DCI 720 of fig. 7) using the additional assumptions described above may be shown in 800 of fig. 8. In this illustrative example, the additional hypothesis 805 is signaled as one of the two-value information (DL control information 1) included in the DCI 801. As previously disclosed, other options may be used. When this additional hypothesis is signaled (in DCI field 803), the second DL control information (denoted as precoding information including the subband PMI) is not signaled. Thus, upon detecting hypothesis 805, the UE may assume a Precoder (PMI) signaled in the most recent previously decoded/received precoding information (e.g., from the most recent decoded/received UL grant). Otherwise, new/updated precoding information is signaled. In this case, the UE should receive/decode the second DL control information including precoding information based on the decoded UL resource allocation in the

DCI

802 or 803.

Any of the above embodiments for supporting subband precoding is applicable to dynamic beamforming and thus may be combined with the mechanisms for semi-dynamic beamforming (as exemplified in tables 1 and 2). That is, for purposes of precoder/beamformer cycling, dynamic beamforming may be associated with the DL control signaling mechanism used for subband precoding, while semi-dynamic beamforming is associated with the DL control mechanism used to indicate the precoder group.

In addition, when dynamic and semi-dynamic beamforming is dynamically configurable for a UE, the UE can also be configured via higher layer (RRC) signaling with a single precoder for all allocated RBs ("wideband" precoding) or subband precoding. In this case, the RRC parameters are used to configure the UE by "wideband" precoding (a single precoder for all allocated RBs) or subband precoding (possibly multiple precoders, each for a subset of allocated RBs). For example, a binary RRC parameter, sub and pre coding enabled, may be used. When its value is "TRUE" or "ON" (ON), the UE is configured with subband precoding. In this case, according to one of the aforementioned four embodiments for subband precoding, a plurality of PMIs (including one PMI depending on the embodiment) may be used. When its value is "FALSE" or "OFF", the UE is configured with "wideband" precoding. In this case, one PMI is used regardless of UE resource allocation.

The above-described exemplary embodiments regarding signaling support for facilitating switching between dynamic and semi-dynamic beamforming and embodiments for supporting subband precoding apply not only to single-stage precoder structures (and thus to single-stage codebooks) but also to dual-stage precoder structures (and thus to dual-stage codebooks).

For the third component (i.e., an implementation with a dual-stage codebook based on a dual-stage precoder), the precoding vector or matrix is combined with two indices (e.g., i ₁ And i ₂ ) In association, wherein the first index indicates wideband components and the second index indicates possible subband components. Examples of such precoder structures are

(similar to Rel.12LTE DL MIMO codebook), wherein +.>

Is wideband (i.e. single stage one precoder +.>

Thus also being i ₁ RB for all allocations), and +.>

Can be broadband or subband (i.e. single-stage-two precoders +.>

Thus also being i ₂ RBs available for different allocations), depending on whether "wideband" precoding or subband precoding is configured for the UE. The pair of indexes (i) ₁ ，i ₂ ) Corresponding to the precoder (vector or matrix) in the configured precoding codebook. First precoder- >

(along with its associated PMI value i ₁ ) May correspond to a precoder group, wherein the second precoder +.>

(along with its associated PMI value i ₂ ) Can correspond to->

A selection and a linear combination of precoder groups. In the case of a dual polarized antenna, a second precoder +.>

(along with its associated PMI value i ₂ ) Co-phase operation between the two polarization sets may also be included.

Furthermore, a two-dimensional bi-level precoder or codebook (particularly geometrically related to a two-dimensional or rectangular array) may be utilized. In this case, the first PMI value i ₁ Can be defined by two indexes (i _1，1 ，i _1，2 ) A composition, each of which corresponds to one of two dimensions. Thus, the corresponding precoder structure may be written as

(similar to Rel.13LTE DL MIMO codebook). Here, the->

Is wideband (i.e. single stage one precoder +.>

Thus also being (i) _1，1 ，i _1，2 ) RB for all allocations) and +.>

Can be broadband or subband (i.e. single-stage-two precoders +.>

Thus also being i ₂ RBs available for different allocations), depending on whether "wideband" precoding or subband precoding is configured for the UE. The index group (i) _1，1 ，i _1，2 ，i ₂ ) Corresponding to the precoder (vector or matrix) in the configured precoding codebook. First precoder->

(along with its associated PMI value (i _1，1 ，i _1，2 ) May correspond to a precoder group, wherein the second precoder +.>

(along with its associated PMI value i ₂ ) Can correspond to->

The following implementations for a dual stage precoder or codebook are applicableFor one-dimensional or two-dimensional precoders. For a two-dimensional precoder or codebook structure, a first PMI value i ₁ Can be defined by two indexes (i _1，1 ，i _1，2 ) The composition is formed. Thus, a first stage precoder may be associated with these two indices:

for example, to configure a UE interchangeably with dynamic or semi-dynamic beamforming for a dual stage precoder, several alternative implementations simulated as the above-described implementations and examples for a single stage precoder are possible. For a dual stage precoder or codebook, the pair of PMI values (i ₁ ，i ₂ ) (or (i) for a two-dimensional precoder _1，1 ，i _1，2 ，i ₂ ) A) may provide natural support for dynamic and semi-dynamic beamforming. When dynamic beamforming is configured, the PMI signaled to the UE includes i ₁ (it is composed of (i) for two-dimensional codebook _1，1 ，i _1，2 ) Constitution) and i ₂ Both of which are located in the same plane. When semi-dynamic beamforming is configured, the PMI signaled to the UE includes only i ₁ (which is composed of (i) for a two-dimensional precoder _1，1 ，i _1，2 ，i ₂ ) Constitute). Values of the second precoder

(along with its associated PMI value i ₂ ) Indicating the precoder set on which a loop should be performed by the UE for its UL data transmission.

In this first embodiment, the PMI field (mentioned earlier) that is part of the DCI in the UL grant may be used for dynamic and semi-dynamic beamforming. Depending on whether the UE is configured with dynamic or semi-dynamic beamforming (i.e.,the PMI field may signal different hypotheses depending on the setting of higher layer parameters indicating whether the UE is configured with dynamic beamforming or semi-dynamic beamforming, or more generally, the first or second transmission scheme). When the UE is configured with dynamic beamforming, the PMI field indicates the precoding matrix or vector that should be used by the UE for licensed UL data transmission. In this case, the PMI field i includes two indexes (which are defined by (i for a two-dimensional codebook _1，1 ，i _1，2 ) Constitution) and codebook i ₂ . When the UE is configured with semi-dynamic beamforming, PMI field i may indicate the selection of a precoding matrix or set of vectors that should be used by the UE for licensed UL data transmission. In this case, the PMI field i includes only i of the same codebook ₁ 。

For example, RRC or higher layer parameter beamformamine scheme is used to indicate whether the UE is configured with dynamic beamforming or semi-dynamic beamforming. When the parameter beamformamingscheme indicates "dynamic" (i.e., dynamic beamforming), pmi= (i) ₁ ，i ₂ ) Indicating that the UE is requested (should) to use the precoder

For UL data transmission. The PMI pair may be jointly encoded as one PMI parameter i or may be separately indicated as two parameters. Pmi=i when the parameter beamformamingscheme indicates "semi-dynamic" (i.e., semi-dynamic beamforming) ₁ Indicating that UE (shall) use is requested and i ₁ (e.g.)>

) An associated precoder group for UL data transmission. For a two-dimensional codebook, i ₁ From (i) _1，1 ，i _1，2 ) The composition is formed.

In addition, when dynamic and semi-dynamic beamforming can be semi-statically configured for a UE via higher layer signaling, the UE can also be configured via higher layer (RRC) signaling with a single precoder for all allocated RBs ("wideband" precoding) or subband precoding. In this case, the RRC parameters are used to configure the UE by "wideband" precoding (a single precoder for all allocated RBs) or subband precoding (possibly multiple precoders, each for a subset of allocated RBs). For example, a binary RRC parameter, sub and pre coding enabled, may be used. When its value is "TRUE" or "ON" (ON), the UE is configured with subband precoding. In this case, according to one of the four aforementioned embodiments for subband precoding, a plurality of PMIs (including one PMI, depending on the embodiment) may be used. When its value is "FALSE" or "OFF", the UE is configured with "wideband" precoding. In this case, one PMI is used regardless of UE resource allocation.

In a second embodiment, the UE is configured dynamically by dynamic or semi-dynamic beamforming, either via a MAC control element (MAC CE) or via UL grant transmitted on a DL control channel.

One example of this second embodiment is to use one DCI parameter to instruct the UE to indicate the selection of a transmission scheme or mode (dynamic or semi-dynamic) that should be used by the UE for licensed UL data transmission (or more generally, the first or second transmission scheme). In this example, the PMI field that is part of the DCI in the UL grant may be used for both dynamic and semi-dynamic beamforming. Depending on the value of the DCI parameter (i.e., whether the UE is configured with dynamic or semi-dynamic beamforming, or more generally, the first or second transmission scheme), a PMI field is also required. When the UE is configured with dynamic beamforming, the PMI field indicates the precoding matrix or vector that should be used by the UE for licensed UL data transmission. When the UE is configured with semi-dynamic beamforming, the PMI field may indicate the selection of a precoding matrix or set of vectors that should be used by the UE for licensed UL data transmission. The DCI field beamformamine scheme has a value of 0 (representing, for example, semi-dynamic beamforming) or a value of 1 (representing, for example, dynamic beamforming).

Another example of this second embodiment is to use only one PMI field as part of the DCI in the UL grant. In this case, consider a field (where N _H ≤2 ^B ) Associated total of N _H A possible assumption, N _H Personal prosthesisSome N in the design _H，d May be utilized to indicate precoder selections for dynamic beamforming, while the remainder (N _H，sd ＝N _H -N _H，d A hypothesis) may be utilized to indicate the selected precoder set for semi-dynamic beamforming.

To facilitate subband precoding for dual stage precoding, several alternative embodiments modeled as the above-described embodiments and examples in fig. 6, 7 and 8 for a single stage precoder may be extended to accommodate a pair of PMI values (i ₁ ，i ₂ ) Wherein i is ₁ (which may be defined by (i) for a two-dimensional codebook _1，1 ，i _1，2 ) Constituted) as a wideband sum i ₂ Is a subband. In this case, with i ₁ (it is composed of (i) for two-dimensional codebook _1，1 ，i _1，2 ) Constitution) remains the same regardless of the number of PMIs or UE resource allocation. That is, only one DCI field requires signaling i ₁ (which may be defined by (i) for a two-dimensional codebook _1，1 ，i _1，2 ) Constitute) regardless of the number of PMIs or UE resource allocation. And i only ₂ The associated number of bits may be scaled or changed according to the number of PMIs or UE resource allocation. Thus, the precoding information includes only one i ₁ (it is composed of (i) for two-dimensional codebook _1，1 ，i _1，2 ) Composition) parameters and possibly a plurality of i ₂ (i ₂ Corresponds to RB groups). In particular, for embodiment 2 (720 of fig. 7) using second-level DL control information including subband PMI, i ₁ May be included in the DCI (or first level DCI) because of i ₁ (which may be defined by (i) for a two-dimensional codebook _1，2 ，i _1，2 ) Constitution) is broadband. Because of i ₂ Is a subband, so the subband PMI included in the second level DL control information includes i for all subbands corresponding to the allocated UL resources ₂ 。

Any of the embodiments for supporting subband precoding is applicable to dynamic beamforming and thus may be combined with the mechanisms for semi-dynamic beamforming. That is, for purposes of precoder/beamformer cycling, dynamic beamforming may be associated with DL control signaling mechanisms for subband precoding, while semi-dynamic beamforming is associated with DL control mechanisms for indicating a precoder group or set.

In addition, when dynamic and semi-dynamic beamforming is dynamically configurable for a UE, the UE can also be configured via higher layer (RRC) signaling with a single precoder for all allocated RBs ("wideband" precoding) or subband precoding. In this case, the RRC parameters are used to configure the UE by "wideband" precoding (a single precoder for all allocated RBs) or subband precoding (possibly multiple precoders, each for a subset of allocated RBs). For example, a binary RRC parameter, sub and pre coding enabled, may be used. When its value is "TRUE" or "ON" (ON), the UE is configured with subband precoding. In this case, according to one of the four aforementioned embodiments for subband precoding, a plurality of PMIs (including one PMI, depending on the embodiment) may be used. When its value is "FALSE" or "OFF", the UE is configured with "wideband" precoding. In this case, one PMI is used regardless of UE resource allocation.

For the fourth component (i.e., supporting reciprocity-based UL transmission), when UL-DL channel reciprocity is feasible, e.g., for TDD scenarios, the UE may obtain an estimate of the UL channel from the measured DL CSI-RS. In this case, the UE may calculate its own precoder for a given resource allocation. This eliminates the need to signal the precoder information DCI field via the DL control channel.

Thus, in one embodiment (4.1), the DCI of the UL grant contains only the number of transmission layers without any PMI (i.e., transmission rank). However, it should be noted that while the UE can obtain an estimate of the UL channel to get its precoder, this precoder calculation may be inaccurate because there is no UL interference information (mainly intra-cell interference, which can only be obtained at the gNB via SRS measurements). This is particularly relevant when UL multi-user MIMO (MU-MIMO). To address this issue, several embodiments are presented in this disclosure-one or some combination of which may be utilized.

In another embodiment (4.2), the same or similar precoding information as described in the component 2 or 3 may be utilized. That is, the DCI for UL grant contains precoding information including one or more PMIs depending on whether "wideband" or subband precoding and/or UE resource allocation is configured. All embodiments presented in the application part 2 or 3 for the precoding information DCI field.

In another embodiment (4.3), the precoding information DCI field containing only a single field is signaled via a DL control channel. The single field may indicate a precoder group or set. The set of precoders can be obtained from a predefined codebook and defined as a subset of all precoders in the codebook. The precoder subset selection may be done for each rank value indicated to the UE via the transmission RI or TRI. In this case, for a given RI (or TRI) value, PMI (or TPMI) indicates a subset or group of precoders specific to the RI (or TRI) value. Alternatively, the precoder subset selection may be done on a codebook associated with all possible values of RI (or TRI). In this case, a single precoder subset or group may be defined that may include precoders from one codebook (associated with one value of RI/TRI) or multiple codebooks (associated with multiple values of RI/TRI). Thus, the PMI/TPMI may be interpreted without any reference or only with partial reference to RI/TRI.

The precoder group or set may include precoders from which the UE should select or combine. That is, since the UE may obtain an estimate of the UL channel via the CSI-RS by utilizing DL-UL channel reciprocity, the UL channel estimate may be used to select or derive a precoder from a combination of a subset or group of precoders indicated via the PMI. This restriction on the subset of precoders may be used (by the gNB) to configure the UE to select the precoder taking into account knowledge of the UL intra-cell interference caused by the gNB scheduling. For example, such selection of the precoder may minimize intra-cell interference caused by the UE to other UEs or intra-cell interference caused by other UEs to the UE. Optionally, the single field may indicate a precoder set that should be avoided by the UE. This avoidance of a subset of precoders may be used (by the gNB) to configure the UE to avoid selecting a precoder taking into account knowledge of UL intra-cell interference caused by the gNB scheduling. For example, such selection of a precoder may exacerbate intra-cell interference caused by the UE to other UEs or intra-cell interference caused by other UEs to the UE.

The same signaling mechanism used for semi-dynamic beamforming may be used in this embodiment. For example, if a single stage precoder or codebook is used, as shown in table 3, a precoding group DCI signaling mechanism similar to table 1 or table 2 for semi-dynamic beamforming may be utilized. Here, G _p The p-th group of B precoders is represented.

Exemplary precoding information table for TDD scenario: primary precoder

[ Table 3 ]

PMI value i	Precoder set
		0	G ₀
1	G ₁
		2	G ₂
…	…
		P-1	G _P-1

If a dual stage precoder or codebook is used, the PMI field in the precoding information field signaled to the UE includes only the first PMIi, which also represents the precoder group ₁ (which may be formed by (i) for a two-dimensional precoder _1，1 ，i _1，2 ) Constitute). Such precoding group signaling is "wideband", i.e. only one field is signaled for any UE resource allocation.

Any of the three embodiments described above may be used for TDD scenarios where DL-UL channel reciprocity is possible. Optionally, at least two of these three embodiments may be supported and configured for the UE via higher layer (RRC) signaling.

When DL CSI-RS is used for UL CSI acquisition (in particular for precoder computation), for this purpose, the UE may be configured by at least one CSI-RS resource. The CSI-RS resource configuration may be the same as or different from the resource configuration used for DL CSI acquisition. Typical CSI-RS resource parameters may be included in the resource configuration such as the number of CSI-RS ports, time domain behavior (periodic, semi-persistent or aperiodic), subframe configuration (which includes subframe frequency shift and periodic-applicable to periodic and semi-persistent CSI-RS), EPRE (energy per RE) or power level, CSI-RS pattern (within one slot/subframe, which also includes frequency density), and when more than one CSI-RS resource may be configured, the number of NZP CSI-RS resources (k≡1).

If the same CSI-RS resource configuration is used for UL CSI acquisition as is used for DL CSI acquisition, higher layer (RRC) parameters may be used to indicate whether the CSI-RS resource configuration corresponds to DL measurements or UL measurements (e.g., CSI, channel, or interference measurements-note that UL and DL interference profiles are typically non-reciprocal). Optionally, the indication may be included in a resource setting or a measurement setting for UL CSI acquisition. Optionally, by configuring the UE with K+.1 CSI-RS resources and dynamically signaling the CSI-RS resource index to the UE via the MAC CE or UL related DCI, an indication from the UL measurements to distinguish usage of the CSI-RS between the DL's may be avoided. The CSI-RS resource index indicates which N (e.g., n=1) of the K configured CSI-RS resources are allocated to the UE for UL CSI measurement/acquisition. In this case, each of the K CSI-RS resources may allocate its own parameters (such as the number of ports, subframe configuration when applicable, mode, etc.).

When the UE is configured with CSI-RS resources for UL CSI measurement, constraints may also be imposed on CSI or precoder computation. For example, it is assumed that the number of UE antenna ports for CSI calculation using DL CSI-RS may be set to the number of SRS antenna ports for corresponding SRS resource setting. Another possible constraint that the UE may assume is the bandwidth of the CSI-RS transmission. When configuring CSI-RS resources for UL measurements, its transmission bandwidth may be set to UL transmission bandwidth, RBs associated with UL resource allocation (especially related to aperiodic CSI-RS) included in UL-related DCI, or preconfigured values (via higher layer/RRC, MAC CE or L1 DL control signaling (e.g., DCI) signaling).

To facilitate the use of DL-UL channel reciprocity for UL transmissions, several alternative implementations may be used.

In one embodiment, in addition to "subband PMI" (one PMI per subband within an allocated resource/RB) and "wideband PMI" (one PMI representing all subbands in an allocated resource/RB), additional "no PMI" configurations and/or "set/group of precoders" configurations may be added. The PMI configuration may be used with a transmission scheme configuration.

In another embodiment, a separate UL transmission scheme may be defined in addition to the existing transmission scheme. For example, in addition to "dynamic beamforming" (or transmission scheme 1) and "semi-dynamic beamforming" (or transmission scheme 2, e.g., diversity-based transmission scheme), a "reciprocity-based" transmission scheme (or transmission scheme 3) may be defined. For example, when the UE is configured with a "reciprocity-based" transmission scheme (or transmission scheme 3), the UE may interpret precoding information (PMI) in the UL-related DCI as an indicator of the set/group of precoders of the UE. Based on DL channel measurements from CSI-RS, the UE may obtain an estimate of the UL channel via DL-UL channel reciprocity. The UL channel estimate may then be used to select or derive a precoder from a combination of a subset or group of precoders indicated via the PMI. Through this process, the UE may calculate a single precoder for all allocated RBs or one precoder for each of the allocated RBs. Such precoder computation may be assigned or left to the UE implementation.

In yet another embodiment, a separate configuration may be defined to indicate that the UE is configured with "reciprocity-based" or "non-reciprocity-based" UL transmissions or precoder calculations or PMI patterns (or PMI interpretations for short). The configuration may be signaled via higher layer (RRC) or L1/L2 control signaling (DCI or MAC CE). Likewise, when the UE is configured with a "non-reciprocity-based" operation, the UE may interpret precoding information (PMI) in the UL-related DCI as an indicator of the set/group of precoders for the UE. Based on DL channel measurements from CSI-RS, the UE may obtain an estimate of the UL channel via DL-UL channel reciprocity. The UL channel estimate may then be used to select or derive a precoder from a combination of a subset or group of precoders indicated via the PMI. Also, through this process, the UE may calculate a single precoder for all allocated RBs, or one precoder for each of the allocated RBs. Such precoder computation may be assigned or left to the UE implementation.

Embodiment 4.3 of the fourth component is described assuming that a single PMI/TPMI indicating the allocated precoder subset/group is used. Thus, if the UE applies frequency selective precoding to the corresponding UL transmission, the UE assumes the same subset/set of precoders for all allocated RBs. However, for high frequency scenarios where allocated RBs may span a wide frequency range, a single precoder set for all allocated RBs may be insufficient. Thus, in a variation of this embodiment, multiple PMIs/TPMI may be included in the UL-related DCI, where each PMI/TPMI indicates a precoder group/subgroup allocation for a particular subband. That is, precoder group/subset allocation is frequency selective. For this variant, any embodiment of the second component with respect to signaling subband PMI/TPMI in UL related DCI is applied. In this case, the subband size or configuration for precoder group/subset allocation may be the same or different from the subband size or configuration for precoder allocation.

For the fifth component (i.e., supporting dual waveform UL transmission), UL transmission may support OFDM (CP-OFDM, i.e., OFDM with cyclic prefix) and DFT-S-OFDM (DFT-spread OFDM), where DFT-S-OFDM is used for single stream transmission. In this case, several possible embodiments may be described as follows.

In one embodiment (5.1), when the UE is configured with UL SU-MIMO, the UE transmits UL data on a physical uplink channel (simulated LTE PUSCH) using CP-OFDM, regardless of the transmission rank (number of transmission layers). When the UE is configured with single stream transmission (not UL SU-MIMO, but without rank adaptation capability), the UE may be configured with CP-OFDM or DFT-S-OFDM. The configuration may be signaled via higher layer (RRC) signaling, MAC control element (MAC CE), or L1 DL control signaling (included in UL-related DCI).

In one variation of embodiment 5.1 (embodiment 5.2), for single stream transmission, the UE may signal its own selection of the multiple access scheme (waveform) via the uplink channel (to the network or gNB) instead of receiving configuration signaling. The signaling may be included as part of UL data transmission or as a separate UL transmission (e.g., transmission on a UL control channel).

In another variation of embodiment 5.1 (embodiment 5.3), the following additional UE processing is supported in addition to the description of embodiment 5.1. When the UE is configured with UL SU-MIMO, a back-off (fallback) transmission scheme of DFT-S-OFDM based single stream transmission is supported. Such a fallback transmission may be dynamically scheduled for the UE via a different UL-related DCI than is used for the UL SU-MIMO transmission. The size of this backoff DCI may be significantly smaller than the size of the UL SU-MIMO transmission and be located in the same search space as that for the UL SU-MIMO transmission or in a different search space (e.g., a common search space). The back-off transmission scheme may be the same or different from the back-off transmission scheme used for single stream transmission associated with non-UL SU-MIMO transmission. Such a transmission scheme may be used, for example, when a UE configured with UL SU-MIMO transmission is in a coverage limited situation.

In another embodiment (5.4), when the UE is configured with UL SU-MIMO, the UE transmits UL data on a physical uplink channel (simulated LTE PUSCH) using CP-OFDM for rank-2 (dual layer transmission) and above. For rank-1 (single layer transmission), the UE may be configured to transmit with CP-OFDM or DFT-S-OFDM. The configuration may be signaled via higher layer (RRC) signaling, MAC CE, or L1 DL control signaling. For the last scheme (via L1 DL control signaling), UL-related DCI associated with UL SU-MIMO transmission includes a one-bit DCI field indicating which waveform (CP-OFDM or DFT-S-OFDM) to use when the value of RI is 1, or both hypotheses (CP-OFDM or DFT-S-OFDM) are encoded jointly with other hypotheses such as RI and/or precoding hypotheses.

In addition, a single precoder (frequency non-selective precoder) is used when the UE transmits with DFT-S-OFDM.

For this embodiment, when the UE is configured with single stream transmission (not UL SU-MIMO, without rank adaptation capability), the UE may be configured with CP-OFDM or DFT-S-OFDM. Likewise, the configuration may be signaled via higher layer (RRC) signaling, MAC control element (MAC CE), or L1 DL control signaling (included in UL-related DCI).

For all the above embodiments, DFT-S-OFDM (single carrier FDMA, SC-FDMA) may be used whenever DFT-S-OFDM is used, where the UE is configured to transmit on a single carrier version of a contiguous set of PRBs.

For all the above embodiments, whenever single-stream transmission is used, transmission diversity or single-port transmission may be used.

The name of the UL transmission channel or waveform is exemplary and may be replaced with other names or labels without changing the essence and/or function of this embodiment.

Fig. 9 shows a flow chart of an example method 900 in which a UE receives a UL grant for UL transmission including precoding information fields associated with a plurality of precoders, according to an embodiment of the disclosure. For example, method 900 may be performed by UE 116.

The method 900 begins with the UE receiving a UL grant for UL transmission (step 901) and decoding a precoding information field in DCI associated with the UL grant, wherein the precoding information field includes at least PMIs corresponding to a plurality of precoders (step 902). The composition of the precoding information field depends on the function of the PMI (step 903). If the PMI is used for a subband precoding indication, the number of PMIs is at least equal to the number of precoders, and at least one PMI is associated with a subband corresponding to at least one RB (step 904). In one option, the number of PMIs may be fixed as indicated in the UL Resource Allocation (RA) field of the DCI, and the number of RBs per subband depends on the allocated RBs. For example, the number of PMIs is at least 2, and the DCI further includes a subband indicator field for one of the PMIs. In another option, at least one PMI associated with the subband is transmitted separately from the DCI including the RA field. If the PMI is used for the precoder group indication, the number of PMIs is 1, and the PMI indicates a group including a plurality of precoders (step 905). In this case, the UE selects a precoder from the group, or derives a precoder from a combination of at least two precoders in the group for licensed UL transmission. Based on this function, a precoder for each of the allocated RBs is determined (step 906). The UE further precodes the data stream and then transmits the data stream on the UL channel (step 907). The UL channel may be a UL control channel (simulated as LTE PUCCH), a UL data channel (simulated as LTE PUSCH), or a combination of both.

Fig. 10 shows a flow chart of an exemplary method according to an embodiment of the present disclosure, in which a BS generates a precoding information field with at least one PMI for a UE (labeled UE-k). For example, method 1000 may be performed by BS 102.

The method 1000 starts with the BS generating a precoding information DCI field with at least one PMI for a UE-k (step 1001). The composition of the precoding information field depends on the function of the PMI (step 1002). If the PMI is used for the subband precoding indication, the number of PMIs is at least equal to the number of precoders, and at least one PMI is associated with a subband corresponding to at least one RB (step 1003). In one option, the number of PMIs may be fixed as indicated in the UL Resource Allocation (RA) field of the DCI, and the number of RBs per subband depends on the allocated RBs. For example, the number of PMIs is at least 2, and the DCI further includes a subband indicator field for one of the PMIs. In another option, at least one PMI associated with the subband is transmitted separately from the DCI including the RA field. If PMI is used for precoder set indication, the number of PMIs is 1, and the PMI indication includes a set of a plurality of precoders (step 1004). Based on this function, the BS generates UL grant with DCI for UL transmission to UE-k (step 1005), and transmits UL grant to UE-k on DL channel (step 1006). The transmission may be accomplished via a DL control channel (modeled as an LTE PDCCH or ePDCCH) or a combination between a DL control channel and a DL data channel (modeled as an LTE PDSCH).

Although fig. 9 and 10 show examples of methods for receiving configuration information and configuring a UE, respectively, various changes may be made to fig. 9 and 10. For example, while shown as a series of steps, various steps in each figure may overlap, occur in parallel, occur in a different order, occur multiple times, or are not performed in one or more embodiments.

While the present disclosure has been described with respect to exemplary embodiments, various changes and modifications may be suggested to one skilled in the art or to one skilled in the art. The disclosure is intended to embrace such alterations and modifications that fall within the scope of the appended claims.

Claims

1. A method for transmitting uplink data by a user equipment, the method comprising:

receiving first information configuring at least one downlink DL CSI-RS resource from a base station;

receiving second information from the base station indicating whether the user equipment is configured with a reciprocity-based uplink UL transmission or a non-reciprocity-based UL transmission, wherein the reciprocity-based UL transmission is related to DL-UL channel reciprocity;

receiving third information from the base station, the third information indicating that an orthogonal frequency division multiplexing CP-OFDM with a cyclic prefix is used for transmitting the uplink data or that a discrete fourier transform spread orthogonal frequency division multiplexing DFT-S-OFDM is used for transmitting the uplink data;

In case the second information indicates that the DL-UL channel is reciprocal, then determining at least one precoder for the UL data based on a measurement result estimated by measuring the at least one DL CSI-RS resource; and

the uplink data is transmitted using the at least one precoder and the transmission waveform of the uplink data determined based on the third information.

2. The method of claim 1, wherein the first information is received through higher layer signaling.

3. The method of claim 1, wherein the second information is received through higher layer signaling.

4. The method of claim 1, wherein the third information is received through higher layer signaling.

5. The method of claim 1, wherein the uplink data comprises a sounding reference signal.

6. A user equipment, comprising:

a transceiver; and

a processor operatively connected to the transceiver,

the processor is configured to:

7. The user equipment of claim 6, wherein the first information is received through higher layer signaling.

8. The user equipment of claim 6, wherein the second information is received through higher layer signaling.

9. The user equipment of claim 6, wherein the third information is received through higher layer signaling.

10. The user equipment of claim 6, wherein the uplink data comprises a sounding reference signal.