Method and apparatus for reference signal signaling for advanced wireless communications

A method of a user equipment (UE) for configuring a phase noise reference signal (RS) in an advanced communication system. The method comprises receiving, from a base station (BS), configuration information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme including information of the phase noise RS; identifying an RS mapping pattern based on the configuration information of the phase noise RS signaled in the RRC and DCI through the hybrid signaling scheme; performing a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW) according to the identified RS mapping pattern; and receiving, from the BS, downlink data over the downlink channel in the scheduled BW.

TECHNICAL FIELD

The present application relates generally to reference signal signaling in advanced wireless communications. More specifically, this disclosure relates to a reference signal design for transmission in a physical downlink channel for data transmissions analogous to physical downlink shared channel (PDSCH) in LTE.

BACKGROUND

A reference signal (RS) can be provided for facilitating demodulation on an antenna port. In orthogonal frequency division multiplexing (OFDM) systems, the reference signal is mapped onto a NRSREs number of resource elements (REs) in a time-frequency resource unit. RS' s for multiple antenna ports can be orthogonally multiplexed time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM) or with a combination of a few of these multiplexing methods. When a CDM is applied, different orthogonal cover codes (OCCs) can be assigned for different antenna ports.

SUMMARY

The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-Generation (4G) communication system such as long term evolution (LTE). Embodiments of the present disclosure provide advanced channel state information (CSI) reporting based on linear combination codebook for multi-input multi-output (MIMO) wireless communication systems wherein advanced CSI comprises at least one of a downlink channel matrix, a covariance matrix of the downlink channel matrix, or at least one eigenvector of the covariance matrix of the downlink channel matrix.

In one embodiment, a user equipment (UE) for configuring a phase noise reference signal (RS) in an advanced communication system is provided. The UE comprises a transceiver configured to receive, from a base station (BS), configuration information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme. The UE further comprises at least one processor configured to identify an RS mapping pattern based on the configuration information of the phase noise RS signaled in the RRC and the DCI through the hybrid signaling scheme and perform a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW) according to the identified RS mapping pattern. The transceiver is further configured to receive, from the BS, downlink data over the downlink channel in the scheduled BW.

In another embodiment, a base station (BS) for configuring a phase noise reference signal (RS) in an advanced communication system is provided. The BS comprises at least one processor configure to generate information of the phase noise RS including an RS mapping pattern, wherein the RS mapping pattern is used, at a user equipment (UE), for a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW). The BS further comprises a transceiver configured to transmit the information of the phase noise RS, to a user equipment (UE), using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme, transmit, to the UE, downlink data over a downlink channel in the scheduled BW, and receive, from the UE, uplink data over an uplink channel in the scheduled BW.

In yet another embodiment, a method of a user equipment (UE) for configuring a phase noise reference signal (RS) in an advanced communication system is provided. The method comprises receiving, from a base station (BS), configuration information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme including information of the phase noise RS, identifying an RS mapping pattern based on the configuration information of the phase noise RS signaled in the RRC and DCI through the hybrid signaling scheme, performing a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW) according to the identified RS mapping pattern; and receiving, from the BS, downlink data over the downlink channel in the scheduled BW.

Aspects, features, and advantages of the present disclosure are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the present disclosure. The present disclosure is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as the duplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assume orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA), this present disclosure can be extended to other OFDM-based transmission waveforms or multiple access schemes such as filtered OFDM (F-OFDM).

This present disclosure covers several components which can be used in conjunction or in combination with one another, or can operate as standalone schemes

DETAILED DESCRIPTION

The following documents and standards descriptions are hereby incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TS 36.211 v13.0.0, “E-UTRA, Physical channels and modulation” (REF1); 3GPP TS 36.212 v13.0.0, “E-UTRA, Multiplexing and Channel coding” (REF2); 3GPP TS 36.213 v13.0.0, “E-UTRA, Physical Layer Procedures” (REF3); and 3GPP TS 36.331 v13.0.0, “Radio Resource Control (RRC) Protocol Specification” (REF4).

The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission coverage, the beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques and the like are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul communication, moving network, cooperative communication, coordinated multi-points (CoMP) transmission and reception, interference mitigation and cancellation and the like.

In the 5G system, hybrid frequency shift keying and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an adaptive modulation and coding (AMC) technique, and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

FIGS. 1-4Bbelow describe various embodiments implemented in wireless communications systems and with the use of OFDM or OFDMA communication techniques. The descriptions ofFIGS. 1-3are not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably-arranged communications system.

FIG. 1illustrates an example wireless network100according to embodiments of the present disclosure. The embodiment of the wireless network100shown inFIG. 1is for illustration only. Other embodiments of the wireless network100could be used without departing from the scope of this disclosure.

As shown inFIG. 1, the wireless network100includes an eNB101, an eNB102, and an eNB103. The eNB101communicates with the eNB102and the eNB103. The eNB101also communicates with at least one network130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

The eNB102provides wireless broadband access to the network130for a first plurality of user equipments (UEs) within a coverage area120of the eNB102. The first plurality of UEs includes a UE111, which may be located in a small business (SB); a UE112, which may be located in an enterprise (E); a UE113, which may be located in a WiFi hotspot (HS); a UE114, which may be located in a first residence (R); a UE115, which may be located in a second residence (R); and a UE116, which may be a mobile device (M), such as a cell phone, a wireless laptop, a wireless PDA, or the like. The eNB103provides wireless broadband access to the network130for a second plurality of UEs within a coverage area125of the eNB103. The second plurality of UEs includes the UE115and the UE116. In some embodiments, one or more of the eNBs101-103may communicate with each other and with the UEs111-116using 5G, LTE, LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can refer to any component (or collection of components) configured to provide wireless access to a network, such as transmit point (TP), transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), gNB, a macrocell, a femtocell, a WiFi access point (AP), or other wirelessly enabled devices. Base stations may provide wireless access in accordance with one or more wireless communication protocols, e.g., 5G 3GPP New Radio Interface/Access (NR), long term evolution (LTE), LTE advanced (LTE-A), High Speed Packet Access (HSPA), Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “eNodeB” and “eNB” are used in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, other well-known terms may be used instead of “user equipment” or “UE,” such as “mobile station,” “subscriber station,” “remote terminal,” “wireless terminal,” or “user device.” For the sake of convenience, the terms “user equipment” and “UE” are used in this patent document to refer to remote wireless equipment that wirelessly accesses an eNB, whether the UE is a mobile device (such as a mobile telephone or smartphone) or is normally considered a stationary device (such as a desktop computer or vending machine).

Dotted lines show the approximate extents of the coverage areas120and125, which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with eNBs, such as the coverage areas120and125, may have other shapes, including irregular shapes, depending upon the configuration of the eNBs and variations in the radio environment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs111-116include circuitry, programing, or a combination thereof, for efficient CSI reporting on an uplink channel in an advanced wireless communication system. In certain embodiments, and one or more of the eNBs101-103includes circuitry, programing, or a combination thereof, for receiving efficient CSI reporting on an uplink channel in an advanced wireless communication system.

AlthoughFIG. 1illustrates one example of a wireless network100, various changes may be made toFIG. 1. For example, the wireless network100could include any number of eNBs and any number of UEs in any suitable arrangement. Also, the eNB101could communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network130. Similarly, each eNB102-103could communicate directly with the network130and provide UEs with direct wireless broadband access to the network130. Further, the eNBs101,102, and/or103could provide access to other or additional external networks, such as external telephone networks or other types of data networks.

FIG. 2illustrates an example eNB102according to embodiments of the present disclosure. The embodiment of the eNB102illustrated inFIG. 2is for illustration only, and the eNBs101and103ofFIG. 1could have the same or similar configuration. However, eNBs come in a wide variety of configurations, andFIG. 2does not limit the scope of this disclosure to any particular implementation of an eNB.

In some embodiment, the RF transceivers210a-210nis capable of transmitting the information of the phase noise RS, to a user equipment (UE), using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme, transmitting, to the UE, downlink data over a downlink channel in the scheduled BW, and receiving, from the UE, uplink data over an uplink channel in the scheduled BW.

In such embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and the uplink channel in the scheduled BW, respectively.

In such embodiments, the DCI includes a modulation and coding scheme to identify the RS mapping pattern when the phase noise RS for the phase tracking is included for a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW, respectively.

In some embodiments, the controller/processor225includes at least one microprocessor or microcontroller. As described in more detail below, the eNB102may include circuitry, programing, or a combination thereof for processing of reference signal on a downlink channel. For example, controller/processor225can be configured to execute one or more instructions, stored in memory230, that are configured to cause the controller/processor to process the reference signal.

The controller/processor225is capable of generating information of the phase noise RS including an RS mapping pattern, wherein the RS mapping pattern is used, at a user equipment (UE), for a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW).

In such embodiments, an RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and the uplink channel in the scheduled BW, respectively.

In such embodiments, a DCI includes a modulation and coding scheme to identify the RS mapping pattern when the phase noise RS for the phase tracking is included for a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW, respectively.

In such embodiments, the DCI comprises a code point indicating whether a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW includes the phase noise RS, respectively and a code point indicating at least one density pattern that is used for a scheduled downlink allocation and a scheduled uplink allocation included in the scheduled BW.

In such embodiments, demodulation reference signal (DMRS) antenna ports corresponding to phase noise RS antenna ports, a phase rotation estimated from the phase noise RS is applied to a channel that is estimated from the DMRS antenna ports, and a number of phase tracking RS antenna ports is less than a number of the DMRS antenna ports in the scheduled BW.

The controller/processor225is capable of identifying demodulation reference signal (DMRS) antenna ports corresponding to phase noise RS antenna ports, wherein a phase rotation estimated from the phase noise RS is applied to a channel that is estimated from the DMRS antenna ports.

In such embodiments, a number of phase tracking RS antenna ports is less than a number of the DMRS antenna ports in the scheduled BW.

AlthoughFIG. 2illustrates one example of eNB102, various changes may be made toFIG. 2. For example, the eNB102could include any number of each component shown inFIG. 2. As a particular example, an access point could include a number of interfaces235, and the controller/processor225could support routing functions to route data between different network addresses. As another particular example, while shown as including a single instance of TX processing circuitry215and a single instance of RX processing circuitry220, the eNB102could include multiple instances of each (such as one per RF transceiver). Also, various components inFIG. 2could be combined, further subdivided, or omitted and additional components could be added according to particular needs.

In some embodiments, the RF transceiver310is capable of receiving, from a base station (BS), configuration information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme and receiving, from the BS, downlink data over the downlink channel in the scheduled BW.

In some embodiments, the RF transceiver310is capable of transmitting, to the BS, uplink data over the uplink channel in the scheduled BW.

In such embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and an uplink channel in the scheduled BW, respectively.

In such embodiments, the DCI includes a modulation and coding scheme to identify whether the phase noise RS is included in a scheduled downlink allocation or a scheduled uplink allocation, and the RS mapping pattern when the phase noise RS for the phase tracking is included in the scheduled downlink allocation and the scheduled uplink allocation over the scheduled BW, respectively.

In such embodiments, the DCI comprises a code point indicating whether a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW includes the phase noise RS, respectively.

In such embodiments, the DCI comprises a code point indicating at least one frequency and time density pattern that is used for a scheduled downlink allocation and a scheduled uplink allocation included in the scheduled BW.

In some embodiments, the processor340is also capable of identifying an RS mapping pattern based on the configuration information of the phase noise RS signaled in the RRC and the DCI through the hybrid signaling scheme, and performing a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW) according to the identified RS mapping pattern.

In some embodiments, the processor340is also capable of performing the channel estimation and phase tracking for an uplink channel in the scheduled BW according to the identified RS mapping pattern.

In such embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and an uplink channel in the scheduled BW, respectively.

In such embodiments, the DCI includes a modulation and coding scheme to identify whether the phase noise RS is included in a scheduled downlink allocation or a scheduled uplink allocation, and the RS mapping pattern when the phase noise RS for the phase tracking is included in the scheduled downlink allocation and the scheduled uplink allocation over the scheduled BW, respectively.

In such embodiments, the DCI comprises a code point indicating whether a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW includes the phase noise RS, respectively.

In such embodiments, the DCI comprises a code point indicating at least one frequency and time density pattern that is used for a scheduled downlink allocation and a scheduled uplink allocation included in the scheduled BW.

In some embodiments, the processor340is also capable of identifying demodulation reference signal (DMRS) antenna ports corresponding to phase noise RS antenna ports and applying, to a channel, a phase rotation estimated from the phase noise RS, wherein the channel is estimated from the DMRS antenna ports.

In such embodiments, a number of phase tracking RS antenna ports is less than a number of the DMRS antenna ports in the scheduled BW.

identifying an RS mapping pattern based on the information of the phase noise RS and performing a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW) according to the identified RS mapping pattern, wherein the transceiver is further configured to receive, from the BS, downlink data over the downlink channel in the scheduled BW.

In some embodiments, the processor340is also capable of performing the channel estimation and phase tracking for an uplink channel in the scheduled BW according to the identified RS mapping pattern.

In such embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and an uplink channel in the scheduled BW, respectively.

In such embodiments, the DCI includes a modulation and coding scheme to identify the RS mapping pattern when the phase noise RS for the phase tracking is included for the downlink channel and an uplink channel in the scheduled BW, respectively.

In such embodiments, the DCI comprises a code point indicating whether the downlink channel and an uplink channel in the scheduled BW includes the phase noise RS, respectively.

In such embodiments, the DCI comprises a code point indicating at least one density pattern that is used for the downlink channel and an uplink channel included in the scheduled BW.

In some embodiments, the processor340is also capable of identifying demodulation reference signal (DMRS) antenna ports corresponding to phase noise RS antenna ports and applying, to a channel, a phase rotation estimated from the phase noise RS, wherein the channel is estimated from the DMRS antenna ports.

In such embodiments, a number of phase tracking RS antenna ports is less than a number of the DMRS antenna ports in the scheduled BW.

FIG. 4Ais a high-level diagram of transmit path circuitry400. For example, the transmit path circuitry400may be used for an orthogonal frequency division multiple access (OFDMA) communication.FIG. 4Bis a high-level diagram of receive path circuitry450. For example, the receive path circuitry450may be used for an orthogonal frequency division multiple access (OFDMA) communication. InFIGS. 4A and 4B, for downlink communication, the transmit path circuitry400may be implemented in a base station (eNB)102or a relay station, and the receive path circuitry450may be implemented in a user equipment (e.g. user equipment116ofFIG. 1). In other examples, for uplink communication, the receive path circuitry450may be implemented in a base station (e.g. eNB102ofFIG. 1) or a relay station, and the transmit path circuitry400may be implemented in a user equipment (e.g. user equipment116ofFIG. 1).

In transmit path circuitry400, channel coding and modulation block405receives a set of information bits, applies coding (e.g., LDPC coding) and modulates (e.g., quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) the input bits to produce a sequence of frequency-domain modulation symbols. Serial-to-parallel block410converts (i.e., de-multiplexes) the serial modulated symbols to parallel data to produce N parallel symbol streams where N is the IFFT/FFT size used in BS102and UE116. Size N IFFT block415then performs an IFFT operation on the N parallel symbol streams to produce time-domain output signals. Parallel-to-serial block420converts (i.e., multiplexes) the parallel time-domain output symbols from Size N IFFT block415to produce a serial time-domain signal. Add cyclic prefix block425then inserts a cyclic prefix to the time-domain signal. Finally, up-converter430modulates (i.e., up-converts) the output of add cyclic prefix block425to RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to RF frequency.

Each of eNBs101-103may implement a transmit path that is analogous to transmitting in the downlink to user equipment111-116and may implement a receive path that is analogous to receiving in the uplink from user equipment111-116. Similarly, each one of user equipment111-116may implement a transmit path corresponding to the architecture for transmitting in the uplink to eNBs101-103and may implement a receive path corresponding to the architecture for receiving in the downlink from eNBs101-103.

FIG. 5illustrates an example structure for a DL subframe500according to embodiments of the present disclosure. An embodiment of the DL subframe structure500shown inFIG. 1is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure. The downlink subframe (DL SF)510includes two slots520and a total of NsymbDLsymbols for transmitting of data information and downlink control information (DCI). The first MsymbDLSF symbols are used to transmit PDCCHs and other control channels530(not shown inFIG. 5). The remaining Z SF symbols are primarily used to transmit physical downlink shared channels (PDSCHs)540,542,544,546, and548or enhanced physical downlink control channels (EPDCCHs)550,552,554, and556. A transmission bandwidth (BW) comprises frequency resource units referred to as resource blocks (RBs). Each RB comprises either NscRBsub-carriers or resource elements (REs) (such as 12 REs). A unit of one RB over one subframe is referred to as a physical RB (PRB). A UE is allocated to MPDSCHRBs for a total of Z=OF+└(ns0+y·NEPDCCH)/D┘ REs for a PDSCH transmission BW. An EPDCCH transmission is achieved in either one RB or multiple of RBs.

A reference signal (RS) can be provided for facilitating demodulation on an antenna port. In OFDM systems, the reference signal is mapped onto a NRSREs number of resource elements (REs) in a time-frequency resource unit. RS' s for multiple antenna ports can be orthogonally multiplexed TDM, FDM, CDM or with a combination of a few of these multiplexing methods. When the CDM is applied, different orthogonal cover codes (OCCs) can be assigned for different antenna ports. In the present disclosure, an RS mapping pattern for an antenna port describes: (1) the time frequency locations of NRSREs number of RSREs; and (2) OCCs if CDM is applied.

In one embodiment, a UE is configured to use either a first RS mapping pattern, or an aggregation of the first and a second RS mapping patterns, for PDSCH demodulation on each antenna port, wherein, the first RS mapping pattern comprises a first set of RSREs (dense in frequency) that enables the UE to estimate the channel response and to take the estimates as demodulation reference, and the second RS mapping pattern includes a second set of RSREs (dense in time) that enable the UE estimate the phase error caused by phase noise.

FIG. 6illustrates example reference signal (RS) patterns600according to embodiments of the present disclosure. An embodiment of the RS patterns600shown inFIG. 6is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure. As shown inFIG. 6, an RS pattern605shows an example of the first RS mapping pattern which is dense in frequency domain to enable the UE to estimate the channels. An RS pattern610inFIG. 6shows an example of the second RS mapping pattern, which is dense in time domain to enable the UE to estimate the phase variation along time. An RS pattern615shows an example for an aggregation of the first and the second RS mapping patterns (e.g., RS pattern605and610, respectively), which has both time domain and frequency domain samples that enable UE to estimate channel in frequency domain and also track the phase variation along time.

FIG. 7Aillustrates an example RS mapping configuration1700according to embodiments of the present disclosure. An embodiment of the RS mapping configuration1700shown inFIG. 7Ais for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

FIG. 7Billustrates an example RS mapping configuration2703according to embodiments of the present disclosure. An embodiment of the RS mapping configuration2703shown inFIG. 7Bis for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

FIG. 7Cillustrates an example RS mapping configuration3705according to embodiments of the present disclosure. An embodiment of the RS mapping configuration3705shown inFIG. 7Cis for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

In some embodiments, for channel estimation and phase noise tracking/estimation for PDSCH demodulation on an antenna port, a UE is configured in a higher layer, with one of the following RS mapping configurations. In one example of a configuration1illustrated inFIG. 7A, the UE uses RS710mapped according to the first RS mapping pattern on the scheduled BW701. In this configuration1, the phase-noise reference signal component is absent in the scheduled PDSCH. This configuration1is useful when phase noise errors are negligible. In another example of configuration2illustrated inFIG. 7B, the UE may use RS710and712mapped according to the aggregation of the first and the second RS mapping patterns on the scheduled BW701. This configuration2is useful when phase noise errors are both Tx and Rx dominant or Tx dominant, in which case a UE-specific reference signal should be used for estimation of phase noise errors for each PDSCH. In yet another example of configuration illustrated inFIG. 7C, the UE may use: (1) the RS710(e.g., first RS) mapped according to the first RS mapping pattern on the scheduled BW701; and (2) a RS711(e.g., second RS) mapped according to the second RS mapping pattern on a separate BW.

An eNB may configure the second RS to be used by a group of UEs; a UE can be informed in a higher layer (e.g., radio resource control (RRC)) of the separate BW, e.g., in terms of identities of time-frequency resource units (e.g., PRBs). This configuration is useful when the phase noise errors are Rx dominant, in which case a common RS can be used for estimation of such phase noise errors at a group of scheduled UEs in a subframe.

In some embodiments, the UE is configured in the higher layer (e.g., RRC) of an information on whether the UE can be provided with phase-noise reference signal (according to the second RS mapping pattern) or not for channel estimation and PDSCH demodulation.

In some embodiments, the UE is dynamically indicated whether the UE is provided with phase-noise reference signal for the channel estimation and demodulation of one given scheduled PDSCH.

The higher-layer configuration can be indicated explicitly through higher layer message or implicitly by carrier frequency to a UE. The dynamic signaling is only enabled when the UE is configured such that the UE can be provided with phase noise reference signal. The information provided in the dynamic signaling can be explicitly indicated via a codepoint in a DCI scheduling the PDSCH for the UE or implicitly via the modulation and coding scheme (MCS) level in the PDSCH for the UE.

When a UE is configured such that the UE can be provided with phase noise reference signal, in one embodiment, the dynamic signaling indicates an RS mapping configuration out of the three RS mapping configurations devised inFIGS. 7A, 7B, and 7Cfor demodulation of the scheduled PDSCH via a state of a codepoint in the DCI. In one example, the dynamic signaling comprises a one bit codepoint on a DCI on a PDCCH. When the state of the 1-bit codepoint equals to 0, the UE is configured to use DMRS generated according to the first configuration (with the first RS mapping pattern only).

When the state of the 1-bit codepoint equals to 1, the UE is configured to use RS mapped according to an aggregation of the first and the second RS mapping patterns (corresponding to Configurations2illustrated inFIGS. 7B and 3illustrated inFIG. 7C). In one embodiment, a UE is configured to use Configuration2. In another embodiment, a UE is configured to use Configuration3. In yet another embodiment, a UE is configured in the higher layer, which of Configuration2and Configuration3may be used in this case.

The RS mapping configuration information can be implicitly indicated by the MCS used/indicated for the scheduled PDSCH in the DCI. In one embodiment, the two cases of the MCS being lower and greater than or equal to an MCS threshold respectively correspond to “state 0” and “state 1” in the above example. In another embodiment, the two cases of the modulation order being lower and greater than or equal to a modulation order threshold (the threshold can be e.g., 4 or 6) respectively correspond to “state 0” and “state 1” in the above example. Similar embodiment can be constructed with the transmission schemes of PDSCH allocation, the number of spatial multiplexing layers of PDSCH allocation, the HARQ redundancy version of PDSCH allocation and combinations thereof.

When the UE is configured such that the UE is not provided with the phase noise reference signals, the codepoint does not exist in the DCI or the UE can assume to ignore the codepoint field in the DCI, and the UE is configured to receive RS according to configuration1(i.e., only a first reference signal pattern is mapped on the scheduled PDSCH).

In one embodiment, carrier frequency and a higher layer configuration are used to indicate an RS mapping configuration. If the carrier frequency is less than a first carrier frequency threshold, the UE is configured with an RS mapping configuration1. If the carrier frequency is greater than or equal to a first carrier frequency threshold, the UE is configured to detect 1 bit in information (in RRC or SIB) and this 1 bit indicates the candidate RS mapping configurations, for example either {configurations1or2} or {configurations1,3}. The selected RS mapping configuration out of the two candidates for each scheduled PDSCH can be dynamically indicated according to some embodiments of the present disclosure.

In another embodiment, if the carrier frequency is below a first carrier frequency threshold, the first reference signal pattern is used (Configuration1) and the DCI does not contain information on the RS mapping configuration. If the carrier frequency is above or equal to a first carrier frequency threshold, the UE is configured to check the state of a codepoint of a DCI scheduling for the PDSCH or to figure out the RS mapping configuration according to some embodiments of the present disclosure.

FIG. 8illustrates example base station (BS) antenna panels800according to embodiments of the present disclosure. An embodiment of the BS antenna panels800shown inFIG. 8is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

As shown inFIG. 8, the BS antenna panels800correspond to DMRS APs allocated to the panels. The BS comprises an Npanel (e.g., 2 in this illustration) number of antenna panels, wherein each panel comprises an NTXRUs (e.g., 4 in this illustration) number of TXRUs, each TXRU mapping to a DMRS AP. In this example, the first four DMRS antenna ports {Np+0, Np+1, Np+2, Np+3}805are mapped to antenna panel1and the second four DMRS antenna ports {Np+4, Np+5, Np+6, Np+7}810are mapped to antenna panel2.

The RS for channel estimation (e.g., mapped according to the first RS mapping pattern) needs to be provided per AP. However, it is not always necessary to provide RS for phase noise estimation (e.g., mapped according to the second RS mapping pattern) per AP. For example, one-port phase-noise RS may be sufficient for UE's demodulation of data on DMRS APs on the same panel. The aim of embodiments is to allow the BS to flexibility configure a mapping between phase noise reference signal antenna port and DMRS antenna ports for different implementation and deployment scenarios. In such embodiments, the UE may use a certain phase-noise RS AP for demodulating data on a given DMRS AP. In one example, one phase noise RS AP is configured to be used for demodulating data on each DMRS antenna port—one-to-one mapping. In another example, one phase noise RS AP is configured to be used for demodulating data on multiple DMRS antenna ports—one-to-many mapping.

In some embodiments, the N1number of antenna ports for the RS for channel estimation and the N2number of antenna ports for RS for phase-noise estimation are separately configured. In one example, N1=8, and N2=2, and: APs for RS for channel estimation {Np+0, Np+1, Np+2, Np+3, Np+4, Np+5, Np+6, Np+7}; and APs for RS for phase-noise estimation {Nq+0, Nq+1}.

The UE can use a first AP (Nq+0) for RS for phase-noise estimation for demodulating data on the first four DMRS APs {Np+0, Np+1, Np+2, Np+3} and a second AP (Nq+1) for RS for phase-noise estimation for demodulating data on the second four DMRS APs {Np+4, Np+5, Np+6, Np+7}.

In some embodiments, the N number of antenna ports are configured for channel estimation and for phase-noise estimation. In one example, in the system with antenna configuration shown inFIG. 8, the UE can receive data on up to 8 antenna ports {Np+0, Np+1, Np+2, Np+3, Np+4, Np+5, Np+6, Np+7}, for each of which RS is provided according to RS mapping configuration2—mapped according to an aggregation of RS mapping patterns1and2in the scheduled BW.

In some embodiments, the UE is configured to use a particular phase-noise RS AP for demodulating data on a DMRS AP. The phase noise RS port q configured to be used for data demodulation on DMRS port p is derived by the equation given by:

q=⌊p-NpNpnrs⌋+Nq
where q is the phase noise RS AP number, p is the DMRS AP number, Npand Nqare the antenna port number offset for phase noise reference signal and DMRS, respectively. The Npnrsmapping parameter is configured by the BS through higher layer signaling (e.g., RRC).

In one example, the DMRS antenna port numbers are {10, 11, 12, . . . , 17} and Np=10 and Nq=100. The BS signals Npnrs=4 to the UE. The UE is configured to calculate the antenna port mapping based on the above equation and configuration received from the BS. The UE may include the phase noise reference signal antenna port100mapping to DMRS antenna {10, 11, 12, 13} and the phase noise reference signal antenna port101mapping to DMRS antenna port {14, 15, 16, 17}. The UE may use the phase noise error estimated from phase noise reference signal antenna port100to compensate the DMRS antenna port {10, 11, 12, 13} and the UE is configured to use the phase noise error estimated from phase noise reference signal antenna port101to compensate the DMRS antenna port {14, 15, 16, 17}.

In some embodiments, the phase noise reference signal component in reference signal may have various time and frequency density. In one example, the time domain density may be every one, two or four OFDM symbols and frequency domain density is every 48 subcarriers. Different time domain density may allow different phase variation limitation. The density configuration of reference signal component for phase noise estimation can be signaled explicitly through a few bits in DCI scheduling a PDSCH/PUSCH or in an RRC signaling configuring a PDSCH/PUSCH transmission. In one example, four preconfigured time domain/frequency domain density of phase noise estimation component is defined and a first 2-bit field in RRC signaling to indicate one out of four preconfigured density structures to a UE.

FIG. 9illustrates a process900for controlling RS according to embodiments of the present disclosure, as may be performed by a UE. An embodiment of the process900shown inFIG. 9is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

The process900for controlling RS begins with the UE116. The UE116receives, in step905, configuration information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme.

In some embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for a downlink channel and an uplink channel in the scheduled BW, respectively. In some embodiments, the DCI includes a modulation and coding scheme (MCS) to identify whether the phase noise RS is included in a scheduled downlink allocation or a scheduled uplink allocation, and the RS mapping pattern when the phase noise RS for the phase tracking is included in the scheduled downlink allocation and the scheduled uplink allocation over the scheduled BW, respectively.

In some embodiments, the DCI further comprises a code point indicating whether a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW includes the phase noise RS, respectively. In some embodiments, the DCI further comprises a code point indicating at least one frequency and time density pattern that is used for a scheduled downlink allocation and a scheduled uplink allocation included in the scheduled BW.

The UE116subsequently identifies, in step910, the RS mapping pattern based on the configuration information of the phase noise RS signaled in the RRC and the DCI in step905through the hybrid signaling scheme.

In some embodiments, the UE116further identifies, in step910, demodulation reference signal (DMRS) antenna ports corresponding to phase noise RS antenna ports and apply, to a channel, a phase rotation estimated from the phase noise RS. In such embodiments, the channel is estimated from the DMRS antenna ports and a number of phase tracking RS antenna ports is less than a number of the DMRS antenna ports in the scheduled BW.

The UE116subsequently performs, in step915, a channel estimation and phase tracking for a downlink channel in the scheduled BW according to the identified RS mapping pattern. In some embodiments, the UE116further performs, in step915, the channel estimation and phase tracking for an uplink channel in the scheduled BW according to the identified RS mapping pattern.

The UE finally receives, in step920, data over the downlink channel in the scheduled BW from the eNB. In some embodiments, the UE is further configured to transmit, to the BS, uplink data over the uplink channel in the scheduled BW.

FIG. 10illustrates another process1000for controlling reference signal according to embodiments of the present disclosure, as may be performed by an base station (BS). An embodiment of the process1000shown inFIG. 10is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

The process1000for controlling RS begins with the base station (BS)102. In step1005, the BS generates information of the phase noise RS including an RS mapping pattern that is used, at a user equipment (UE), for a channel estimation and phase tracking for a downlink channel in a scheduled bandwidth (BW). Subsequently, the BS transmits, in step1010, the information of the phase noise RS using a radio resource control (RRC) signal and downlink control information (DCI) through a hybrid signaling scheme.

In some embodiments, the RRC signal includes information indicating whether the phase noise RS for the phase tracking is included for the downlink channel and the uplink channel in the scheduled BW, respectively. In some embodiments, the DCI includes a modulation and coding scheme to identify the RS mapping pattern when the phase noise RS for the phase tracking is included for a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW, respectively. In some embodiments, the DCI comprises a code point indicating whether a scheduled downlink allocation and a scheduled uplink allocation in the scheduled BW includes the phase noise RS, respectively and a code point indicating at least one density pattern that is used for a scheduled downlink allocation and a scheduled uplink allocation included in the scheduled BW.

Subsequently, the BS transmits, in step1015, downlink data over a downlink channel in the scheduled BW to the UE. Finally, the BS receives, in step1020, uplink date over an uplink channel in the scheduled BW from the UE.

A first time domain/frequency domain density configuration can be used for UE with small phase noise variation. A second time domain/frequency domain density configuration can be used for UE with large phase noise. A third and a fourth time domain/frequency domain density configuration can be used for UE who is capable to compensate the inter-subcarrier interference caused by phase noise.

None of the description in this application should be read as implying that any particular element, step, or function is an essential element that must be included in the claims scope. The scope of patented subject matter is defined only by the claims. Moreover, none of the claims are intended to invoke 35 U.S.C. § 112(f) unless the exact words “means for” are followed by a participle.