EP4229816A1

EP4229816A1 - Method and apparatus for transmitting/receiving phase tracking reference signal in wireless communication system

Info

Publication number: EP4229816A1
Application number: EP21880265.0A
Authority: EP
Inventors: Andrey PUDEEV; Suckchel Yang; Jiwon Kang; Seunghwan Choi; Seonwook Kim; Alexander Maltsev
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2020-10-16
Filing date: 2021-04-26
Publication date: 2023-08-23
Also published as: WO2022080613A1

Abstract

The present disclosure relates to a method and an apparatus for transmitting or receiving a downlink phase tracking reference signal (PTRS) and/or uplink PTRS in a wireless communication system. According to an aspect of the present invention, the PTRS is received in one or more PTRS subcarrier groups within a specific scheduled bandwidth. Each PTRS subcarrier group includes one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. The one or more null PTRS subcarriers are determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for DL data as scheduled by a DCI.

Description

METHOD AND APPARATUS FOR TRANSMITTING/RECEIVING PHASE TRACKING REFERENCE SIGNAL IN WIRELESS COMMUNICATION SYSTEM

The present disclosure relates to a method and an apparatus for transmitting or receiving a downlink (DL) phase tracking reference signal (PT-RS) and/or uplink (UL) PTRS in a wireless communication system.

Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless access system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.) among them. For example, multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system.

Provided are a method and apparatus for efficiently performing a wireless signal transmission and reception procedure.

It will be appreciated by persons skilled in the art that the objects that could be achieved with the present disclosure are not limited to what has been particularly described hereinabove and the above and other objects that the present disclosure could achieve will be more clearly understood from the following detailed description .

According to an aspect of the present invention, a method of receiving a signal by a user equipment (UE) in a wireless communication system, may include receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); receiving downlink control information (DCI) scheduling DL data; and receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be received in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. And, the one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

A processor readable medium recorded thereon instruction for executing the method can be provided according to other aspect of the present invention.

According to another aspect of the present invention, a device for processing a signal for wireless communication, may include a memory configured to store instructions; and a processor configured to perform operations, by executing the instructions. The operations may include an operation for receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); an operation for receiving downlink control information (DCI) scheduling DL data; and an operation for receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be received in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. And, the one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the downlink data as scheduled by the DCI. The device may further include a transceiver configured to transmit or receive signals under control of the processor. The device may be a user equipment (UE) configured to operate in a 3rd generation partnership project (3GPP)-based wireless communication system.

According to another aspect of the present invention, a method of transmitting a signal by a base station (BS) in a wireless communication system, may include transmitting, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); transmitting downlink control information (DCI) scheduling DL data; and transmitting in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. The one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

According to another aspect of the present invention, a base station (BS) for wireless communication, may include a transceiver; a memory configured to store instructions; and a processor configured to perform operations, by executing the instructions. The operations may include an operation for transmitting, via the transceiver through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); an operation for transmitting, via the transceiver, downlink control information (DCI) scheduling DL data; and an operation for transmitting, via the transceiver, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. The one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

The one or more PTRS subcarrier groups may include a first PTRS subcarrier group and a second PTRS subcarrier group which are apart from each other in a frequency domain, and a distance between the first PTRS subcarrier group and the second PTRS subcarrier group may be determined based on a size of the specific scheduled bandwidth.

The one or more active PTRS subcarriers can be power boosted based on freed power from the one or more null PTRS subcarriers. For example, the one or more active PTRS subcarriers can be power boosted based a ratio of X/(X-N), where 'X' denotes a total number of subcarriers per 1-PTRS subcarrier group, and 'N' denotes a number of null PTRS subcarriers per 1-PTRS subcarrier group.

The configuration regarding the PTRS include information regarding at least one of a number of the one or more PTRS subcarrier groups, a size of 1-PTRS subcarrier group, a distance between neighboring PTRS subcarrier groups, a number of the null PTRS subcarriers per 1-PTRS subcarrier group, or at least one power boost level for the one or more active PTRS subcarriers.

The DCI may include information regarding a power boost level applied to the one or more active PTRS subcarriers from among one or more power boost levels configured through the configuration regarding the PTRS.

The one or more active PTRS subcarriers may locate at a center of each PTRS subcarrier group through localized mapping; and the one or more null subcarriers may locate at edges of each PTRS subcarrier group.

The less null PTRS subcarriers may be used for lager SCS. The more null PTRS subcarriers may be used for a wider phase noise bandwidth.

The number of the one or more null PTRS subcarriers may satisfy a formula floor{(X-1)/2}, where 'X' denotes a total number of subcarriers per 1-PTRS subcarrier group.

The DCI can be received through a physical downlink control channel (PDCCH), the DL data can be received through a physical downlink shared channel (PDSCH), and the DL signal may include the PDSCH and a demodulation reference signal (DMRS) for the PDSCH.

The above-describe aspects of the present disclosure are merely a part of preferred embodiments of the present disclosure, and those skilled in the art will derive and understand various embodiments reflecting technical features of the present disclosure based on the following detailed description of the present disclosure.

According to embodiments of the present disclosure, a signal may be efficiently transmitted and received in a wireless communication system.

It will be appreciated by persons skilled in the art that the effects that can be achieved with the present disclosure are not limited to what has been particularly described hereinabove and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure.

In the drawings:

FIG. 1 illustrates physical channels and a general signal transmission method using the physical channels in a 3 ^rd generation partnership project (3GPP) system as an exemplary wireless communication system;

FIG. 2 illustrates network initial access and a subsequent communication process;

FIG. 3 illustrates a discontinuous reception (DRX) cycle;

FIG. 4 illustrates a radio frame structure;

FIG. 5 illustrates a resource grid during the duration of a slot;

FIG. 6 illustrates exemplary mapping of physical channels in a slot;

FIG. 7 illustrates exemplary uplink (UL) transmission operations of a user equipment (UE);

FIG. 8 illustrates exemplary repeated transmissions based on a configured grant;

FIG. 9 illustrates a wireless communication system supporting an unlicensed band;

FIG. 10 illustrates 3GPP phase noise model;

FIG. 11 illustrates examples of the pilot (i.e., PTRS) allocations variants;

FIG. 12 illustrates PTRS allocations with nulling according to an embodiment of present invention;

FIG. 13 illustrates a 3GPP Rel. 15 based PTRS allocations example (without nulling);

FIG. 14 illustrates a Distributed pilot allocation with nulling example according to an embodiment of present invention;

FIG. 15 illustrates a result and comparison regarding simulations of Rel.15 (e.g., FIG 13) and Nulling (e.g., FIG 14) for K = 2, 5 tap filter, 64 QAM;

FIG. 16 illustrates a result and comparison regarding simulations of Rel.15 (e.g., FIG 13) and Nulling (e.g., FIG 14) for K = 2, 5 tap filter, 64 QAM;

FIG. 17 illustrates a result and comparison regarding simulations of Rel.15 (e.g., FIG 13) and Nulling (e.g., FIG 14) for K = 4, 3- and 5-tap filters, 256 QAM

FIG. 18 illustrates PTRS allocation in a frequency domain according to an embodiment of present invention;

FIG. 19 illustrates an example of DL PTRS according to an embodiment of present invention;

FIG. 20 illustrates an example of UL PTRS according to an embodiment of present invention;

FIG. 21 illustrates an exemplary communication system applied to the present disclosure;

FIG. 22 illustrates an exemplary wireless device applicable to the present disclosure;

FIG. 23 illustrates another exemplary wireless device applicable to the present disclosure; and

FIG. 24 illustrates an exemplary vehicle or autonomous driving vehicle applicable to the present disclosure.

The following technology may be used in various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and so on. CDMA may be implemented as a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented as a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented as a radio technology such as institute of electrical and electronics engineers (IEEE) 802.11 (wireless fidelity (Wi-Fi)), IEEE 802.16 (worldwide interoperability for microwave access (WiMAX)), IEEE 802.20, evolved UTRA (E-UTRA), and so on. UTRA is a part of universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA, and LTE-advanced (LTE-A) is an evolution of 3GPP LTE. 3GPP new radio or new radio access technology (NR) is an evolved version of 3GPP LTE/LTE-A.

As more and more communication devices require larger communication capacities, the need for enhanced mobile broadband communication relative to the legacy radio access technologies (RATs) has emerged. Massive machine type communication (MTC) providing various services to inter-connected multiple devices and things at any time in any place is one of significant issues to be addressed for next-generation communication. A communication system design in which services sensitive to reliability and latency are considered is under discussion as well. As such, the introduction of the next-generation radio access technology (RAT) for enhanced mobile broadband communication (eMBB), massive MTC (mMTC), and ultra-reliable and low latency communication (URLLC) is being discussed. For convenience, this technology is called NR or New RAT in the present disclosure.

While the following description is given in the context of a 3GPP communication system (e.g., NR) for clarity, the technical spirit of the present disclosure is not limited to the 3GPP communication system. For the background art, terms, and abbreviations used in the present disclosure, refer to the technical specifications published before the present disclosure (e.g., 3GPP TS 38.211, 38.212, 38.213, 38.214, 38.300, 38.331, and so on).

Also, following documents can be incorporated by references:

[1] RP-200902, Study on supporting NR from 52.6GHz to 71 GHz

[2] D. Petrovic, W. Rave, and G. Fettweis, “Intercarrier interference due to phase noise in OFDM-Estimation and suppression,” in Proc. IEEE VTC Fall, Sep. 2004, pp. 2191-2195.

[3] Maltsev, A., Maslennikov, R., Khoryaev, A. Influence of phase noise on OFDM data transmission systems. Radiophysics and Quantum Electronics, 2011, vol. 53, no. 8, p. 475-487.

[4] 3GPP TR 38.803 V14.2.0 (2017-09) “Study on new radio access technology: Radio Frequency (RF) and co-existence aspects”

[5] V. Syrjala, T. Levanen, T. Ihalainen and M. Valkama, “Pilot Allocation and Computationally Efficient Non-Iterative Estimation of Phase Noise in OFDM,” IEEE Wireless Comm Letters, Apr. 2019.

[6] 3GPP TS38.211V15.8.0(2019-12) “Physical channels and modulation (Release 15)”

[7] D. Petrovic, W. Rave and G. Fettweis, “Effects of Phase Noise on OFDM Systems With and Without PLL: Characterization and Compensation,” IEEE Trans. Comm., Aug. 2007.

[8] R1-2005922 “On Phase Noise Compensation for OFDM”

[9] 3GPP TR 38.901 V16.1.0 (2019-12), “Study on channel model for frequencies from 0.5 to 100 GHz (Release 16)”

In a wireless access system, a user equipment (UE) receives information from a base station (BS) on DL and transmits information to the BS on UL. The information transmitted and received between the UE and the BS includes general data and various types of control information. There are many physical channels according to the types/usages of information transmitted and received between the BS and the UE.

FIG. 1 illustrates physical channels and a general signal transmission method using the physical channels in a 3GPP system.

When a UE is powered on or enters a new cell, the UE performs initial cell search (S11). The initial cell search involves acquisition of synchronization to a BS. For this purpose, the UE receives a synchronization signal block (SSB) from the BS. The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The UE synchronizes its timing to the BS and acquires information such as a cell identifier (ID) based on the PSS/SSS. Further, the UE may acquire information broadcast in the cell by receiving the PBCH from the BS. During the initial cell search, the UE may also monitor a DL channel state by receiving a downlink reference signal (DL RS).

After the initial cell search, the UE may acquire more detailed system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) corresponding to the PDCCH (S12).

Subsequently, to complete connection to the BS, the UE may perform a random access procedure with the BS (S13 to S16). Specifically, the UE may transmit a preamble on a physical random access channel (PRACH) (S13) and may receive a PDCCH and a random access response (RAR) for the preamble on a PDSCH corresponding to the PDCCH (S14). The UE may then transmit a physical uplink shared channel (PUSCH) by using scheduling information in the RAR (S15), and perform a contention resolution procedure including reception of a PDCCH and a PDSCH signal corresponding to the PDCCH (S16).

When the random access procedure is performed in two steps, steps S13 and S15 may be performed as one step (in which Message A is transmitted by the UE), and steps S14 and S16 may be performed as one step (in which Message B is transmitted by the BS).

After the above procedure, the UE may receive a PDCCH and/or a PDSCH from the BS (S17) and transmit a physical uplink shared channel (PUSCH) and/or a physical uplink control channel (PUCCH) to the BS (S18), in a general UL/DL signal transmission procedure. Control information that the UE transmits to the BS is generically called uplink control information (UCI). The UCI includes a hybrid automatic repeat and request acknowledgement/negative acknowledgement (HARQ-ACK/NACK), a scheduling request (SR), channel state information (CSI), and so on. The CSI includes a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indication (RI), and so on. In general, UCI is transmitted on a PUCCH. However, if control information and data should be transmitted simultaneously, the control information and the data may be transmitted on a PUSCH. In addition, the UE may transmit the UCI aperiodically on the PUSCH, upon receipt of a request/command from a network.

The UE may perform a network access procedure to perform the described/proposed procedures and/or methods (FIGS. 11 to 18). For example, the UE may receive and store system information and configuration information required to perform the above-described/proposed procedures and/or methods during network (e.g., BS) access. The configuration information required for the present disclosure may be received by higher-layer signaling (e.g., radio resource control (RRC) signaling, medium access control (MAC) signaling, or the like).

FIG. 2 is a diagram illustrating a signal flow for network initial access and a subsequent communication process. In NR, a physical channel and an RS may be transmitted by beamforming. When beamforming-based signal transmission is supported, a beam management process may be performed to align beams between a BS and a UE. Further, a signal proposed in the present disclosure may be transmitted/received by beamforming. In RRC_IDLE mode, beam alignment may be performed based on an SSB, whereas in RRC_CONNECTED mode, beam alignment may be performed based on a channel state information reference signal (CSI-RS) (in DL) and a sounding reference signal (SRS) (in UL). When beamforming-based signal transmission is not supported, a beam-related operation may be skipped in the following description.

Referring to FIG. 2, a BS may periodically transmit an SSB (S2102). The SSB includes a PSS/SSS/PBCH. The SSB may be transmitted by beam sweeping. Subsequently, the BS may transmit remaining minimum system information (RMSI) and other system information (OSI) (S2104). The RMSI may include information (e.g., PRACH configuration information) required for a UE to initially access the BS. After SSB detection, the UE identifies a best SSB. The UE may then transmit an RACH preamble (Message 1 (Msg 1)) to the BS in PRACH resources linked/corresponding to the index (i.e., beam) of the best SSB (S2106). The beam direction of the RACH preamble is associated with the PRACH resources. The association between the PRACH resources (and/or RACH preamble) and the SSB (index) may be configured by system information (e.g., RMSI). Subsequently, as a part of the RACH process, the BS may transmit an RAR (Msg 2) in response to the RACH preamble (S2108), and the UE may transmit Msg 3 (e.g., RRC Connection Request) using a UL grant in the RAR (S2110). The BS may transmit a contention resolution message (Msg 4) (S2112). Msg 4 may include an RRC Connection Setup message. Msg 1 and Msg 3 may be combined (e.g., into Msg A) and transmitted in one step, and Msg 2 and Msg 4 may be combined (e.g., into Msg B) and transmitted in one step.

When an RRC connection is established between the BS and the UE through the RACH process, subsequent beam alignment may be performed based on an SSB/CSI-RS (in DL) and an SRS (in UL). For example, the UE may receive the SSB/CSI-RS (S2114). The UE may use the SSB/CSI-RS to generate a beam/CSI report. The BS may request a beam/CSI report to the UE by downlink control information (DCI) (S2116). In this case, the UE may generate a beam/CSI report based on the SSB/CSI-RS, and transmit the generated beam/CSI report to the BS on a PUSCH/PUCCH (S2118). The beam/CSI report may include a beam measurement result, preferred beam information, and the like. The BS and the UE may switch beams based on the beam/CSI report (S2120a and S2120b).

Subsequently, the UE and the BS may perform the later-described/proposed procedures and/or methods (FIGS. 11 to 18). For example, the UE and the BS may process information stored in memories and transmit a wireless signal or process a received wireless signal and store the processed wireless signal in the memories, according to a proposal in the present disclosure based on configuration information obtained during the network access procedure (e.g., the system information acquisition process, the RRC connection process through an RACH, and so on). The wireless signal may include at least one of a PDCCH, a PDSCH, or an RS on DL, and at least one of a PUCCH, a PUSCH, or an SRS on UL.

FIG. 3 is a diagram illustrating a DRX cycle (RRC_CONNECTED state).

Referring to FIG. 3, the DRX cycle includes On Duration and Opportunity for DRX. The DRX cycle defines a time interval in which On Duration is periodically repeated. On Duration is a time period during which the UE monitors to receive a PDCCH. When DRX is configured, the UE performs PDCCH monitoring during the On Duration. When there is any successfully detected PDCCH during the PDCCH monitoring, the UE operates an inactivity timer and is maintained in an awake state. On the other hand, when there is no successfully detected PDCCH during the PDCCH monitoring, the UE enters a sleep state, when the On Duration ends. Therefore, if DRX is configured, PDCCH monitoring/reception may be performed discontinuously in the time domain, when the afore-described/proposed procedures and/or methods are performed. For example, if DRX is configured, PDCCH reception occasions (e.g., slots having PDCCH search spaces) may be configured discontinuously according to a DRX configuration in the present disclosure. On the contrary, if DRX is not configured, PDCCH monitoring/reception may be performed continuously in the time domain, when the afore-described/proposed procedures and/or methods are performed. For example, if DRX is not configured, PDCCH reception occasions (e.g., slots having PDCCH search spaces) may be configured continuously in the present disclosure. PDCCH monitoring may be limited in a time period configured as a measurement gap, irrespective of whether DRX is configured.

Table 1 describes a UE operation related to DRX (in the RRC_CONNECTED state). Referring to Table 1, DRX configuration information is received by higher-layer (RRC) signaling, and DRX ON/OFF is controlled by a DRX command of the MAC layer. Once DRX is configured, the UE may perform PDCCH monitoring discontinuously in performing the described/proposed procedures and/or methods according to the present disclosure, as illustrated in FIG. 3.

[Table 1]

MAC-CellGroupConfig includes configuration information required to configure MAC parameters for a cell group. MAC-CellGroupConfig may also include DRX configuration information. For example, MAC-CellGroupConfig may include the following information in defining DRX.

- Value of drx-OnDurationTimer: defines the length of the starting duration of a DRX cycle.

- Value of drx-InactivityTimer: defines the length of a time duration in which the UE is in the awake state after a PDCCH occasion in which a PDCCH indicating initial UL or DL data has been detected.

- Value of drx-HARQ-RTT-TimerDL: defines the length of a maximum time duration from reception of a DL initial transmission to reception of a DL retransmission.

- Value of drx-HARQ-RTT-TimerDL: defines the length of a maximum time duration from reception of a grant for a DL initial transmission to reception of a grant for a UL retransmission.

- drx-LongCycleStartOffset: defines the time duration and starting time of a DRX cycle.

- drx-ShortCycle (optional): defines the time duration of a short DRX cycle.

When at least one of drx-OnDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL, or drx-HARQ-RTT-TimerDL is running, the UE performs PDCCH monitoring in each PDCCH occasion, while staying in the awake state.

For example, according to an embodiment of the present disclosure, when DRX is configured for a UE of the present disclosure, the UE may receive a DL signal during On Duration.

FIG. 4 illustrates a radio frame structure.

In NR, UL and DL transmissions are configured in frames. Each radio frame has a length of 10ms and is divided into two 5-ms half-frames. Each half-frame is divided into five 1-ms subframes. A subframe is divided into one or more slots, and the number of slots in a subframe depends on a subcarrier spacing (SCS). Each slot includes 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP). When a normal CP is used, each slot includes 14 OFDM symbols. When an extended CP is used, each slot includes 12 OFDM symbols. A symbol may include an OFDM symbol (or a CP-OFDM symbol) and an SC-FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol).

Table 2 exemplarily illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to SCSs in a normal CP case.

[Table 2]

* N ^slot _symb: number of symbols in a slot

* N ^frame,u _slot: number of slots in a frame

* N ^subframe,u _slot: number of slots in a subframe

Table 3 illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to SCSs in an extended CP case.

[Table 3]

The frame structure is merely an example, and the number of subframes, the number of slots, and the number of symbols in a frame may be changed in various manners.

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CP lengths, and so on) may be configured for a plurality of cells aggregated for one UE. Accordingly, the (absolute time) duration of a time resource (e.g., a subframe, a slot, or a transmission time interval (TTI)) (for convenience, referred to as a time unit (TU)) composed of the same number of symbols may be configured differently between the aggregated cells.

In NR, various numerologies (or SCSs) may be supported to support various 5 ^th generation (5G) services. For example, with an SCS of 15kHz, a wide area in traditional cellular bands may be supported, while with an SCS of 30kHz or 60kHz, a dense urban area, a lower latency, and a wide carrier bandwidth may be supported. With an SCS of 60kHz or higher, a bandwidth larger than 24.25kHz may be supported to overcome phase noise.

An NR frequency band may be defined by two types of frequency ranges, FR1 and FR2. FR1 and FR2 may be configured as described in Table 4 below. FR2 may be millimeter wave (mmW).

[Table 4]

FIG. 5 illustrates a resource grid during the duration of one slot.

A slot includes a plurality of symbols in the time domain. For example, one slot includes 14 symbols in a normal CP case and 12 symbols in an extended CP case. A carrier includes a plurality of subcarriers in the frequency domain. A resource block (RB) may be defined by a plurality of (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) may be defined by a plurality of consecutive (physical) RBs ((P)RBs) in the frequency domain and correspond to one numerology (e.g., SCS, CP length, and so on). A carrier may include up to N (e.g., 5) BWPs. Data communication may be conducted in an active BWP, and only one BWP may be activated for one UE. Each element in a resource grid may be referred to as a resource element (RE), to which one complex symbol may be mapped.

FIG. 6 illustrates exemplary mapping of physical channels in a slot.

A DL control channel, DL or UL data, and a UL control channel may all be included in one slot. For example, the first N symbols (hereinafter, referred to as a DL control region) in a slot may be used to transmit a DL control channel, and the last M symbols (hereinafter, referred to as a UL control region) in the slot may be used to transmit a UL control channel. N and M are integers equal to or greater than 0. A resource region (hereinafter, referred to as a data region) between the DL control region and the UL control region may be used for DL data transmission or UL data transmission. A time gap for DL-to-UL or UL-to-DL switching may be defined between a control region and the data region. A PDCCH may be transmitted in the DL control region, and a PDSCH may be transmitted in the DL data region. Some symbols at the time of switching from DL to UL in a slot may be configured as the time gap.

Now, a detailed description will be given of physical channels.

The PDSCH delivers DL data (e.g., a downlink shared channel (DL-SCH) transport block (TB)) and adopts a modulation scheme such as quadrature phase shift keying (QPSK), 16-ary quadrature amplitude modulation (16 QAM), 64-ary QAM (64 QAM), or 256-ary QAM (256 QAM). A TB is encoded to a codeword. The PDSCH may deliver up to two codewords. The codewords are individually subjected to scrambling and modulation mapping, and modulation symbols from each codeword are mapped to one or more layers. An OFDM signal is generated by mapping each layer together with a DMRS to resources, and transmitted through a corresponding antenna port.

The PDCCH delivers DCI. For example, the PDCCH (i.e., DCI) may carry information about a transport format and resource allocation of a DL shared channel (DL-SCH), resource allocation information of an uplink shared channel (UL-SCH), paging information on a paging channel (PCH), system information on the DL-SCH, information on resource allocation of a higher-layer control message such as an RAR transmitted on a PDSCH, a transmit power control command, information about activation/release of configured scheduling, and so on. The DCI includes a cyclic redundancy check (CRC). The CRC is masked with various identifiers (IDs) (e.g. a radio network temporary identifier (RNTI)) according to an owner or usage of the PDCCH. For example, if the PDCCH is for a specific UE, the CRC is masked by a UE ID (e.g., cell-RNTI (C-RNTI)). If the PDCCH is for a paging message, the CRC is masked by a paging-RNTI (P-RNTI). If the PDCCH is for system information (e.g., a system information block (SIB)), the CRC is masked by a system information RNTI (SI-RNTI). When the PDCCH is for an RAR, the CRC is masked by a random access-RNTI (RA-RNTI).

The PDCCH uses a fixed modulation scheme (e.g., QPSK). One PDCCH includes 1, 2, 4, 8, or 16 control channel elements (CCEs) according to its aggregation level (AL). One CCE includes 6 resource element groups (REGs), each REG being defined by one OFDM symbol by one (P)RB.

The PDCCH is transmitted in a control resource set (CORESET). The CORESET corresponds to a set of physical resources/parameters used to deliver the PDCCH/DCI in a BWP. For example, the CORESET is defined as a set of REGs with a given numerology (e.g., an SCS, a CP length, or the like). The CORESET may be configured by system information (e.g., a master information block (MIB)) or UE-specific higher-layer signaling (e.g., RRC signaling). For example, the following parameters/information may be used to configure a CORESET, and a plurality of CORESETs may overlap with each other in the time/frequency domain.

- controlResourceSetId: indicates the ID of a CORESET.

- frequencyDomainResources: indicates the frequency area resources of the CORESET. The frequency area resources are indicated by a bitmap, and each bit of the bitmap corresponds to an RB group (i.e., six consecutive RBs). For example, the most significant bit (MSB) of the bitmap corresponds to the first RB group of a BWP. An RB group corresponding to a bit set to 1 is allocated as frequency area resources of the CORESET.

- duration: indicates the time area resources of the CORESET. It indicates the number of consecutive OFDMA symbols in the CORESET. For example, the duration is set to one of 1 to 3.

- cce-REG-MappingType: indicates a CCE-to-REG mapping type. An interleaved type and a non-interleaved type are supported.

- precoderGranularity: indicates a precoder granularity in the frequency domain.

- tci-StatesPDCCH: provides information indicating a transmission configuration indication (TCI) state for the PDCCH (e.g., TCI-StateID). The TCI state is used to provide the quasi-co-location relation between DL RS(s) in an RS set (TCI-state) and PDCCH DMRS ports.

- tci-PresentInDCI: indicates whether a TCI field is included in DCI.

- pdcch-DMRS-ScramblingID: provides information used for initialization of a PDCCH DMRS scrambling sequence.

To receive the PDCCH, the UE may monitor (e.g., blind-decode) a set of PDCCH candidates in the CORESET. The PDCCH candidates are CCE(s) that the UE monitors for PDCCH reception/detection. The PDCCH monitoring may be performed in one or more CORESETs in an active DL BWP on each active cell configured with PDCCH monitoring. A set of PDCCH candidates monitored by the UE is defined as a PDCCH search space (SS) set. The SS set may be a common search space (CSS) set or a UE-specific search space (USS) set.

Table 5 lists exemplary PDCCH SSs.

[Table 5]

The SS set may be configured by system information (e.g., MIB) or UE-specific higher-layer (e.g., RRC) signaling. S or fewer SS sets may be configured in each DL BWP of a serving cell. For example, the following parameters/information may be provided for each SS set. Each SS set may be associated with one CORESET, and each CORESET configuration may be associated with one or more SS sets.

- searchSpaceId: indicates the ID of the SS set.

- controlResourceSetId: indicates a CORESET associated with the SS set.

- monitoringSlotPeriodicityAndOffset: indicates a PDCCH monitoring periodicity (in slots) and a PDCCH monitoring offset (in slots).

- monitoringSymbolsWithinSlot: indicates the first OFDMA symbol(s) for PDCCH monitoring in a slot configured with PDCCH monitoring. The OFDMA symbols are indicated by a bitmap and each bit of the bitmap corresponds to one OFDM symbol in the slot. The MSB of the bitmap corresponds to the first OFDM symbol of the slot. OFDMA symbol(s) corresponding to bit(s) set to 1 corresponds to the first symbol(s) of the CORESET in the slot.

- nrofCandidates: indicates the number of PDCCH candidates (e.g., one of 0, 1, 2, 3, 4, 5, 6, and 8) for each AL={1, 2, 4, 8, 16}.

- searchSpaceType: indicates whether the SS type is CSS or USS.

- DCI format: indicates the DCI format of PDCCH candidates.

The UE may monitor PDCCH candidates in one or more SS sets in a slot based on a CORESET/SS set configuration. An occasion (e.g., time/frequency resources) in which the PDCCH candidates should be monitored is defined as a PDCCH (monitoring) occasion. One or more PDCCH (monitoring) occasions may be configured in a slot.

Table 6 illustrates exemplary DCI formats transmitted on the PDCCH.

[Table 6]

DCI format 0_0 may be used to schedule a TB-based (or TB-level) PUSCH, and DCI format 0_1 may be used to schedule a TB-based (or TB-level) PUSCH or a code block group (CBG)-based (or CBG-level) PUSCH. DCI format 1_0 may be used to schedule a TB-based (or TB-level) PDSCH, and DCI format 1_1 may be used to schedule a TB-based (or TB-level) PDSCH or a CBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0/0_1 may be referred to as UL grant DCI or UL scheduling information, and DCI format 1_0/1_1 may be referred to as DL grant DCI or DL scheduling information. DCI format 2_0 is used to deliver dynamic slot format information (e.g., a dynamic slot format indicator (SFI)) to a UE, and DCI format 2_1 is used to deliver DL pre-emption information to a UE. DCI format 2_0 and/or DCI format 2_1 may be delivered to a corresponding group of UEs on a group common PDCCH which is a PDCCH directed to a group of UEs.

DCI format 0_0 and DCI format 1_0 may be referred to as fallback DCI formats, whereas DCI format 0_1 and DCI format 1_1 may be referred to as non-fallback DCI formats. In the fallback DCI formats, a DCI size/field configuration is maintained to be the same irrespective of a UE configuration. In contrast, the DCI size/field configuration varies depending on a UE configuration in the non-fallback DCI formats.

The PUCCH delivers uplink control information (UCI). The UCI includes the following information.

- SR: information used to request UL-SCH resources.

- HARQ-ACK: a response to a DL data packet (e.g., codeword) on the PDSCH. An HARQ-ACK indicates whether the DL data packet has been successfully received. In response to a single codeword, a 1-bit of HARQ-ACK may be transmitted. In response to two codewords, a 2-bit HARQ-ACK may be transmitted. The HARQ-ACK response includes positive ACK (simply, ACK), negative ACK (NACK), discontinuous transmission (DTX) or NACK/DTX. The term HARQ-ACK is interchangeably used with HARQ ACK/NACK and ACK/NACK.

- CSI: feedback information for a DL channel. Multiple input multiple output (MIMO)-related feedback information includes an RI and a PMI.

Table 7 illustrates exemplary PUCCH formats. PUCCH formats may be divided into short PUCCHs (Formats 0 and 2) and long PUCCHs (Formats 1, 3, and 4) based on PUCCH transmission durations.

[Table 7]

PUCCH format 0 conveys UCI of up to 2 bits and is mapped in a sequence-based manner, for transmission. Specifically, the UE transmits specific UCI to the BS by transmitting one of a plurality of sequences on a PUCCH of PUCCH format 0. Only when the UE transmits a positive SR, the UE transmits the PUCCH of PUCCH format 0 in PUCCH resources for a corresponding SR configuration.

PUCCH format 1 conveys UCI of up to 2 bits and modulation symbols of the UCI are spread with an orthogonal cover code (OCC) (which is configured differently whether frequency hopping is performed) in the time domain. The DMRS is transmitted in a symbol in which a modulation symbol is not transmitted (i.e., transmitted in time division multiplexing (TDM)).

PUCCH format 2 conveys UCI of more than 2 bits and modulation symbols of the DCI are transmitted in frequency division multiplexing (FDM) with the DMRS. The DMRS is located in symbols #1, #4, #7, and #10 of a given RB with a density of 1/3. A pseudo noise (PN) sequence is used for a DMRS sequence. For 2-symbol PUCCH format 2, frequency hopping may be activated.

PUCCH format 3 does not support UE multiplexing in the same PRBS, and conveys UCI of more than 2 bits. In other words, PUCCH resources of PUCCH format 3 do not include an OCC. Modulation symbols are transmitted in TDM with the DMRS.

PUCCH format 4 supports multiplexing of up to 4 UEs in the same PRBS, and conveys UCI of more than 2 bits. In other words, PUCCH resources of PUCCH format 3 include an OCC. Modulation symbols are transmitted in TDM with the DMRS.

The PUSCH delivers UL data (e.g., UL-shared channel transport block (UL-SCH TB)) and/or UCI based on a CP-OFDM waveform or a DFT-s-OFDM waveform. When the PUSCH is transmitted in the DFT-s-OFDM waveform, the UE transmits the PUSCH by transform precoding. For example, when transform precoding is impossible (e.g., disabled), the UE may transmit the PUSCH in the CP-OFDM waveform, while when transform precoding is possible (e.g., enabled), the UE may transmit the PUSCH in the CP-OFDM or DFT-s-OFDM waveform. A PUSCH transmission may be dynamically scheduled by a UL grant in DCI, or semi-statically scheduled by higher-layer (e.g., RRC) signaling (and/or Layer 1 (L1) signaling such as a PDCCH) (configured scheduling or configured grant). The PUSCH transmission may be performed in a codebook-based or non-codebook-based manner.

On DL, the BS may dynamically allocate resources for DL transmission to the UE by PDCCH(s) (including DCI format 1_0 or DCI format 1_1). Further, the BS may indicate to a specific UE that some of resources pre-scheduled for the UE have been pre-empted for signal transmission to another UE, by PDCCH(s) (including DCI format 2_1). Further, the BS may configure a DL assignment periodicity by higher-layer signaling and signal activation/deactivation of a configured DL assignment by a PDCCH in a semi-persistent scheduling (SPS) scheme, to provide a DL assignment for an initial HARQ transmission to the UE. When a retransmission for the initial HARQ transmission is required, the BS explicitly schedules retransmission resources through a PDCCH. When a DCI-based DL assignment collides with an SPS-based DL assignment, the UE may give priority to the DCI-based DL assignment.

Similarly to DL, for UL, the BS may dynamically allocate resources for UL transmission to the UE by PDCCH(s) (including DCI format 0_0 or DCI format 0_1). Further, the BS may allocate UL resources for initial HARQ transmission to the UE based on a configured grant (CG) method (similarly to SPS). Although dynamic scheduling involves a PDCCH for a PUSCH transmission, a configured grant does not involve a PDCCH for a PUSCH transmission. However, UL resources for retransmission are explicitly allocated by PDCCH(s). As such, an operation of preconfiguring UL resources without a dynamic grant (DG) (e.g., a UL grant through scheduling DCI) by the BS is referred to as a "CG". Two types are defined for the CG.

- Type 1: a UL grant with a predetermined periodicity is provided by higher-layer signaling (without L1 signaling).

- Type 2: the periodicity of a UL grant is configured by higher-layer signaling, and activation/deactivation of the CG is signaled by a PDCCH, to provide the UL grant.

FIG. 7 illustrates exemplary UL transmission operations of a UE. The UE may transmit an intended packet based on a DG (FIG. 7(a)) or based on a CG (FIG. 7(b)).

Resources for CGs may be shared between a plurality of UEs. A UL signal transmission based on a CG from each UE may be identified by time/frequency resources and an RS parameter (e.g., a different cyclic shift or the like). Therefore, when a UE fails in transmitting a UL signal due to signal collision, the BS may identify the UE and explicitly transmit a retransmission grant for a corresponding TB to the UE.

K repeated transmissions including an initial transmission are supported for the same TB by a CG. The same HARQ process ID is determined for K times repeated UL signals based on resources for the initial transmission. The redundancy versions (RVs) of a K times repeated TB have one of the patterns {0, 2, 3, 1}, {0, 3, 0, 3}, and {0, 0, 0, 0}.

FIG. 8 illustrates exemplary repeated transmissions based on a CG.

The UE performs repeated transmissions until one of the following conditions is satisfied:

- A UL grant for the same TB is successfully received;

- The repetition number of the TB reaches K; and

- (In Option 2) the ending time of a period P is reached.

When there are UL/DL transmission data for multiple UEs in a wireless communication system, the BS selects a UE for data transmission in each TTI (e.g., slot). In a multi-carrier system and a similar system, the BS selects UEs for UL/DL data transmission and also selects frequency bands to be used for the data transmission for the UEs.

From the perspective of UL, the UEs transmit RSs (or pilots) on UL. The BS then determines the channel states of the UEs based on the RSs received from the UEs and selects UEs for UL data transmission in respective unit frequency bands in each TTI. The BS indicates these results to the UEs. That is, the BS transmits a UL assignment message requesting data transmission in a specific frequency band to a UE which has been scheduled for UL transmission in a specific TTI. The UL assignment message is also called a UL grant. The UE transmits data on UL according to the UL assignment message. The UL assignment message may include a UE ID, RB allocation information, a modulation and coding scheme (MCS), an RV, a new data indication (NDI), and so on.

In synchronous HARQ, a retransmission timing is pre-agreed at a system level (e.g., 4 subframes after a NACK reception time). Accordingly, the BS transmits a UL grant message to the UE only at an initial transmission, and subsequent retransmissions are performed based on an ACK/NACK signal (e.g., PHICH signal). In asynchronous HARQ, a retransmission timing is not agreed between the BS and the UE, and thus the BS should transmit a retransmission request message to the UE. Further, in non-adaptive HARQ, the same frequency resources and the same MCS may be used for a previous transmission and a retransmission, whereas in adaptive HARQ, different frequency resources and different MCSs may be used for a previous transmission and a retransmission. In asynchronous adaptive HARQ, for example, retransmission frequency resources or a retransmission MCS is changed at each transmission time. Therefore, a retransmission request message may include a UE ID, RB allocation information, an HARQ process ID/number, an RV, and NDI information.

In NR, a dynamic HARQ-ACK codebook scheme and semi-static HARQ-ACK codebook scheme are supported. The term HARQ-ACK (or A/N) codebook may be replaced with HARQ-ACK payload.

When the dynamic HARQ-ACK codebook scheme is configured, the size of A/N payload varies according to the amount of actually scheduled DL data. For this purpose, a PDCCH related to DL scheduling includes a counter-downlink assignment index (DAI) and a total-DAI. The counter-DAI indicates a {CC, slot} scheduling order calculated in a component carrier (CC) (or cell)-first manner and is used to indicate the position of an A/N bit in an A/N codebook. The total-DAI indicates a slot-level scheduling accumulative value up to the current slot and is used to determine the size of the A/N codebook.

When the semi-static HARQ-ACK codebook scheme is configured, the size of an A/N codebook is fixed (to a maximum value) irrespective of the amount of actually scheduled DL data. Specifically, (a maximum) A/N payload (size) transmitted on one PUCCH in one slot may be determined to be the number of A/N bits corresponding to combinations (hereinafter, referred to as a bundling window) of all CCs configured for the UE and DL scheduling slots (or PDSCH transmission slots to PDCCH monitoring slots) available as the A/N transmission timing. For example, DL grant DCI (PDCCH) may include PDSCH-to-A/N timing information, and the PDSCH-to-A/N timing information may have one (e.g., k) of a plurality of values. For example, when a PDSCH is received in slot #m and PDSCH-to-A/N timing information in DL grant DCI (PDCCH) that schedules the PDSCH indicates k, A/N information for the PDSCH may be transmitted in slot #(m+k). For example, k ∈ {1, 2, 3, 4, 5, 6, 7, 8}. When A/N information is transmitted in slot #n, the A/N information may include as many A/Ns as possible based on a bundling window. That is, the A/N information in slot #n may include an A/N corresponding to slot #(n-k). For example, when k ∈ {1, 2, 3, 4, 5, 6, 7, 8}, the A/N information in slot #n includes A/Ns (i.e., a maximum number of A/Ns) corresponding to slot #(n-8) to slot #(n-1) irrespective of actual DL data reception. A/N information may be replaced with A/N codebook or A/N payload. Further, a slot may be understood as/replaced with a candidate occasion for DL data reception. As in the example, the bundling window may be determined based on a PDSCH-to-A/N timing based on an A/N slot, and a PDSCH-to-A/N timing set may have predefined values (e.g., {1, 2, 3, 4, 5, 6, 7, 8}) or may be configured by higher-layer (RRC) signaling.

Similarly to licensed-assisted access (LAA) in the legacy 3GPP LTE system, use of an unlicensed band for cellular communication is also under consideration in a 3GPP NR system. Unlike LAA, a stand-along (SA) operation is aimed in an NR cell of an unlicensed band (hereinafter, referred to as NR unlicensed cell (UCell)). For example, PUCCH, PUSCH, and PRACH transmissions may be supported in the NR UCell.

In an NR system to which various embodiments of the present disclosure are applicable, up to 400MHz per component carrier (CC) may be allocated/supported. When a UE operating in such a wideband CC always operates with a radio frequency (RF) module turned on for the entire CC, battery consumption of the UE may increase.

Alternatively, considering various use cases (e.g., eMBB, URLLC, mMTC, and so on) operating within a single wideband CC, a different numerology (e.g., SCS) may be supported for each frequency band within the CC.

Alternatively, each UE may have a different maximum bandwidth capability.

In this regard, the BS may indicate to the UE to operate only in a partial bandwidth instead of the total bandwidth of the wideband CC. The partial bandwidth may be defined as a bandwidth part (BWP).

A BWP may be a subset of contiguous RBs on the frequency axis. One BWP may correspond to one numerology (e.g., SCS, CP length, slot/mini-slot duration, and so on).

The BS may configure multiple BWPs in one CC configured for the UE. For example, the BS may configure a BWP occupying a relatively small frequency area in a PDCCH monitoring slot, and schedule a PDSCH indicated (or scheduled) by a PDCCH in a larger BWP. Alternatively, when UEs are concentrated on a specific BWP, the BS may configure another BWP for some of the UEs, for load balancing. Alternatively, the BS may exclude some spectrum of the total bandwidth and configure both-side BWPs of the cell in the same slot in consideration of frequency-domain inter-cell interference cancellation between neighboring cells.

The BS may configure at least one DL/UL BWP for a UE associated with the wideband CC, activate at least one of DL/UL BWP(s) configured at a specific time point (by L1 signaling (e.g., DCI), MAC signaling, or RRC signaling), and indicate switching to another configured DL/UL BWP (by L1 signaling, MAC signaling, or RRC signaling). Further, upon expiration of a timer value (e.g., a BWP inactivity timer value), the UE may switch to a predetermined DL/UL BWP. The activated DL/UL BWP may be referred to as an active DL/UL BWP. During initial access or before an RRC connection setup, the UE may not receive a configuration for a DL/UL BWP from the BS. A DL/UL BWP that the UE assumes in this situation is defined as an initial active DL/UL BWP.

FIG. 9 illustrates an exemplary wireless communication system supporting an unlicensed band applicable to the present disclosure.

In the following description, a cell operating in a licensed band (L-band) is defined as an L-cell, and a carrier of the L-cell is defined as a (DL/UL) LCC. A cell operating in an unlicensed band (U-band) is defined as a U-cell, and a carrier of the U-cell is defined as a (DL/UL) UCC. The carrier/carrier-frequency of a cell may refer to the operating frequency (e.g., center frequency) of the cell. A cell/carrier (e.g., CC) is commonly called a cell.

When a BS and a UE transmit and receive signals on carrier-aggregated LCC and UCC as illustrated in FIG. 9(a), the LCC and the UCC may be configured as a primary CC (PCC) and a secondary CC (SCC), respectively. The BS and the UE may transmit and receive signals on one UCC or on a plurality of carrier-aggregated UCCs as illustrated in FIG. 9(b). In other words, the BS and UE may transmit and receive signals only on UCC(s) without using any LCC. For an SA operation, PRACH, PUCCH, PUSCH, and SRS transmissions may be supported on a UCell.

Signal transmission and reception operations in an unlicensed band as described in the present disclosure may be applied to the afore-mentioned deployment scenarios (unless specified otherwise).

Unless otherwise noted, the definitions below are applicable to the following terminologies used in the present disclosure.

Channel: a carrier or a part of a carrier composed of a contiguous set of RBs in which a channel access procedure (CAP) is performed in a shared spectrum.

- Channel access procedure (CAP): a procedure of assessing channel availability based on sensing before signal transmission in order to determine whether other communication node(s) are using a channel. A basic sensing unit is a sensing slot with a duration of Tsl = 9us. The BS or the UE senses the slot during a sensing slot duration. When power detected for at least 4us within the sensing slot duration is less than an energy detection threshold Xthresh, the sensing slot duration Tsl is be considered to be idle. Otherwise, the sensing slot duration Tsl is be considered to be busy. CAP may also be called listen before talk (LBT).

- Channel occupancy: transmission(s) on channel(s) from the BS/UE after a CAP.

- Channel occupancy time (COT): a total time during which the BS/UE and any BS/UE(s) sharing channel occupancy performs transmission(s) on a channel after a CAP. Regarding COT determination, if a transmission gap is less than or equal to 25us, the gap duration may be counted in a COT. The COT may be shared for transmission between the BS and corresponding UE(s).

- DL transmission burst: a set of transmissions without any gap greater than 16us from the BS. Transmissions from the BS, which are separated by a gap exceeding 16us are considered as separate DL transmission bursts. The BS may perform transmission(s) after a gap without sensing channel availability within a DL transmission burst.

- UL transmission burst: a set of transmissions without any gap greater than 16us from the UE. Transmissions from the UE, which are separated by a gap exceeding 16us are considered as separate UL transmission bursts. The UE may perform transmission(s) after a gap without sensing channel availability within a DL transmission burst.

- Discovery burst: a DL transmission burst including a set of signal(s) and/or channel(s) confined within a window and associated with a duty cycle. The discovery burst may include transmission(s) initiated by the BS, which includes a PSS, an SSS, and a cell-specific RS (CRS) and further includes a non-zero power CSI-RS. In the NR system, the discover burst includes may include transmission(s) initiated by the BS, which includes at least an SS/PBCH block and further includes a CORESET for a PDCCH scheduling a PDSCH carrying SIB1, the PDSCH carrying SIB1, and/or a non-zero power CSI-RS.

Phase Tracking Reference Signal (PTRS)

PTRS is employed in 5G NR wireless communication system Rel. 16. The NR standard document 3GPP TS 38.211 v16.3.0 and 3GPP TS 38.214 v16.3.0 define the PTRS as table 8 and table 9, respectively.

[Table 8]

[Table 9]

Meanwhile, recent advancements in the communication technologies and an ever-growing data traffic capacity demands drives the 5G NR spec towards higher frequency bands and subjected a new study item on the support of the frequencies from 52.6 GHz to 71 GHz [1]. It is noted that the key challenge for the OFDM systems in the millimeter-wave bands it is a phase noise [2] that causes severe inter-carrier interference (ICI) and prohibits the operation of the spectrally efficient higher order modulations without a specific phase tracking and ICI compensation algorithms application. The performance of these algorithms strongly depends on training sequences design and functions. Although such sequences already included on the 5G NR specification, the expansion to the 52-71 GHz band may require reconsideration of the current spec solutions.

Advancement to 52-71 GHz band requires dealing with the increased phase noise which cannot be neglected anymore and may prevent the higher order modulations to be functional. The current NR specification, although designed to support lower frequencies than 52-71 GHz band, has enough flexibility to avoid or to compensate the phase noise impact at least for that lower frequencies.

Figure 10 shows the power spectral density (PSD) of the phase noise, corresponded to the model currently accepted as a main model for simulations and analysis [4]. For convenience, 5G NR subcarrier spacing (SCS) values (including those that are not supported in current NR specification but discussed to be introduced for frequency range from 52.6 GHz to 71 GHz) are shown along the frequency axis. It can be seen that the amount of out-of-subcarrier noise, that corresponds to the ICI term is different for different subcarrier spacing, so the higher SCSs are much less susceptible to the negative phase noise impact.

Analysis of the phase noise influence on an OFDM system [2][3][5]shows that the overall phase noise (PN) impact can be divided in the two components - the common phase error (CPE), and the inter-carrier interference (ICI). The first term is common for all subcarriers on the given OFDM symbol, but largely fluctuating for different symbols. The second term describes influence of the adjacent OFDM subcarriers on the given one due to signal spreading caused by multiplicative phase noise.

While the first term may be rather easily mitigated by finding a common phase shift for the OFDM symbol, the compensation of the ICI may require more advanced algorithms and pilot structures. Current 3GPP 5G NR specification (as shown in Tables 8 and 9 define the PTRSs as a grid of selected resource elements (REs), sparsely distributed in frequency. Spec allows changing also time density of the PTRS symbols, but for the frequencies of interests, the PN has weak correlations between OFDM symbols and PTRSs should be used on every OFDM symbol for proper compensation.

FIG. 11 illustrates examples of the pilot (i.e., PTRS) allocations variants.

Both pilots’ allocations (e.g., FIG. 11) have its limitations and features. The clustered variant has non-optimal pilot usage since cluster-edge subcarriers are omitted (e.g., cluster-edge subcarriers may be unavailable for PTRS transmission as illustrated as dotted line in FIGURE 11b)), due to ICI from neighboring data subcarriers (adjacent to the cluster). The distributed pilots allocation can be easily scaled and agnostic to pilot locations, but have limited performance in its LS variant, due to quick loss of the estimation accuracy with the increase of the filter size.

FIG. 12 illustrates PTRS allocations with nulling.

In an aspect of present invention, we propose modification to the both of the mentioned PTRS allocation approaches - both to distributed and clustered allocation that includes disabling the neighboring to the active PTRS subcarriers (e.g., nulling one more subcarriers neighboring to the active PTRS subcarrier). For example, subcarriers (reserved) for PTRS may include (i) active PTRS subcarriers on which a PTRS sequence is mapped and allocated with non-zero power, and (ii) null (PTRS) subcarriers. The null subcarriers may be allocated with (substantially/almost) zero-power. The PTRS sequence may not be mapped on the null subcarriers (or punctured). In one embodiment, for the distributed PTRS allocation, one or more subcarriers can be disabled (nulled) at the both sides of the active PTRS (active PTRS subcarriers) (e.g., see Figure 12a). In another embodiment, the nulling can be applied to the subcarriers in a cluster that are not directly used in the estimations (e.g., Figure 12b). In some embodiments, the freed power (which is based on nulling the subcarriers) may be redirected to the active PTRS (i.e.., power boosting for active PTRS), boosting its SNR for both allocation cases.

Hereafter, a subcarrier to which nulling is performed/required) for the active PTRS subcarrier may be a null PTRS subcarrier or a null subcarrier or just simply Nulls.

For evaluation of the proposed allocation methods performance, the nulling methods was implemented in the 5G NR links layer simulator (LLS), resembling the performance of the real NR system in the frequency selective channel under influence of the phase noise and thermal noise impairments.

To keep the comparison fair, the amount of resources allocated for PTRS was the same for every compared scheme, so the amount of active + nulled subcarriers for the case of nulling was equal to the number of PTRSs in the baseline Rel. 15 case. So, the number of active PTRSs for the case of nulling is smaller than the number of PTRS subcarriers for the case of 3GPP NR Rel. 15. The power is also equalized for the both cases, by boosting the center active pilots (PTRS subcarriers) in the nulling case.

Figure 13 and Figure 14 illustrate the data allocation (PDSCH) structure for the baseline Rel-15 and proposed distributed allocation with side subcarrier nulling.

The performance of the considered PTRS structures were investigated for the SCS 480 kHz in the 400 MHz band. Two PTRS frequency density cases were considered: parameter K = 2 (where K corresponds to frequency density parameter K _PT-RS in above Table 8) with 32 PT-RS REs (i.e., 32 PTRS subcarriers in 400 MHz band) allocated for PTRS at every symbol (Figure 15) and K = 4 with 16 PTRS REs allocated every symbol (Figure 16). (For example, K _PT-RS = m, PRTS mapping may be performed for 1-RB per every m-RB.)

An OFDM signal with a TX-side phase noise was propagated through a frequency selective channel described by TDL-A model [9], with normalized delay spread of 10ns and Jakes Doppler spectrum corresponding to 3 km/h. 1x2 SIMO system was modeled, with the MRC processing and practical DMRS based channel estimation scheme at the receiver.

Before the applications of the phase noise ICI compensation algorithms, a simple CPE compensation were performed. The BER curves corresponding to the cases of CPE compensation and to the case when no compensation is performed are also plotted on the resulting graphs for reference.

For more dense allocation with PTRS parameter K = 2, two subcarriers were nulled from each side, producing only 6 active pilots per 32 allocated REs, distributed along the band. For sparse allocation with K = 4, with 16 allocated RE we have 5 active pilots with single subcarrier at both sides nulled.

In both cases, it can be seen that the simple LS algorithm, applied to the nulled PTRS allocation gives better phase noise compensation than the same LS algorithms applied to the Rel. 15 PTRSs, approximately by 0.7-0.9 dB in terms of Uncoded BER.

For the other SCS/density combination, the nulling operation may give less or comparable improvement, but never loses to the Rel.15 PTRS structure.

Besides shown performance improvement, the nulled PTRS design will have advantages in all cases where the inter-carrier interference may affect the performance - for example for the high-Doppler scenarios.

Proposals

Proposal 1: DL/UL clustered (localized mapping)/Distributed PT-RS can be used by UE or BS. Configuration for the PTRS can be configured in a UE (e.g., higher layer signaling). A UE can be configured with "clustered PT-RS" (FIG. 19 1505/FIG. 20 1605). The clustered PT-RS (resources) may be composed of (or mapped to) C chunk(s) where the size of a chunk is X REs (subcarriers). The chunks may be consecutive or may be apart from each other (by a distance based on a specific rule or configuration). In the latter case, the distance between adjacent chunks (e.g., distance between Chunk #i and Chunk #i+1) in a frequency domain is D REs (or RBs). (Hereafter, "RE" can be replaced as "subcarrier" in the frequency domain.)

Proposal 2: For clustered PT-RS, N REs within a chunk can be nulled and the number of active PT-RS RE(s) can be {X - N}. All (or a part) of {X - N} active PT-RS RE(s) can be power-boosted with the ratio of R. The number/location of the N (<X) REs can be determined based on the chunk size X. For example, for a given X (>3), N/2 REs at one side of a chunk and N/2 REs at the other side of the chunk can be nulled (i.e., in total, N REs at both sides within each chunk are nulled). For another example, for a given X, N can be determined/configured as floor{(X-1)/2} so that X = 2N + 1. Here, the floor {M} means a largest integer not exceeding a value 'M'. For another example, with X=3, 1 RE at one side of a chunk and 1 RE at the other side of the chunk can be nulled (i.e., in total, 2 REs at both sides within each chunk are nulled). The power-boosting ratio, R, can be derived from a function of N and X. That is, R can be determined based on a plurality of parameters including at least one of N and X. R can increase as N increases. For example, active PT-RS RE(s) can be power-boosted based on a ratio of X/(X-N). For example, the ratio of R = X/(X-N). Figure 18 illustrate mentioned parameters X, N, D and R by showing PTRS subcarriers allocations in a frequency domain.

Proposal 3: For DL PT-RS reception and/or UL PT-RS transmission, a UE can determine/receive/obtain one or more of the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R) based on network signaling. For example, a UE can be configured with information regarding the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R) parameter(s) by higher layer signaling such as RRC and MAC CE (e.g., FIG. 19 1505/FIG. 20 1605). The value of parameter(s) or the range of the values can be differently configured/determined according to at least one of scheduled bandwidth, scheduled MCS value, SCS, and PN PSD bandwidth. A base station can transmit/receive DL/UL PT-RS based on one or more of the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R). DL/UL PT-RS signal/sequence generation and/or mapping can be performed based on one or more of the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R).

- In more detail: As shown in Tables 10 and 11, the values of D, X and N can be configured with respect to scheduled MCS and scheduled bandwidth, respectively. Higher layer parameters ptrs-MCSi (i=1,2,3,4...) and N_RBj (j=0,1) can be configured to the UE. I_MCS and N_RB correspond to actually scheduled MCS value and actually scheduled number of RBs, respectively, via DCI (e.g., FIG. 19 1510) scheduling PDSCH in case of DL PTRS (or DCI scheduling PUSCH in case of UL PTRS, e.g., FIG. 20 1610). For example, with a configuration of ptrs-MCS3=20, ptrs-MCS4=29, and N_RB1=100, if a UE is scheduled with PDSCH with I_MCS=25, N_RB=150, the UE receives the clustered PT-RS with X=5, N=2 and D=6 RBs (e.g., FIG. 19 1550).

Table 10 represents Chunk size of PT-RS (and/or Null subcarriers) as a function of scheduled MCS (non-limiting example).

[Table 10]

For example, the number of the active PTRS subcarriers (or the size of Chunk and/or the number of null subcarriers) may increase as modulation order of corresponding data gets high.

Table 11 represents Frequency density of PT-RS as a function of scheduled bandwidth (non-limiting example).

[Table 11]

Proposal 4: For PT-RS reception, a UE can be configured with multiple candidate R values by higher layer signaling such as RRC and MAC CE and one of the values can be (explicitly or implicitly) indicated via a DCI scheduling PDSCH. For example, with explicit manner, additional DCI field can be added to the DCI to indicate which R value out of configured multiple candidate values can be applied. For another example, with implicit manner, one of the values can be determined by UE according to DCI scheduling status (e.g. multi-UE or single-UE, or depending on the number of CDM groups and antenna ports, or depending on the number of CDM groups to be rate-matched for data) with existing DCI field(s).

Obviously, above proposals can be applied/extended to the cases of two-port PT-RS (where the proposals can be applied to each port) and UL PT-RS (especially when transform precoder is disabled).

Examples

According to at least one embodiment of this application:

- Pilot subcarrier (e.g., subcarrier(s) allocated for Phase-Tracking Reference Signal) may be consisted of the single active subcarrier or (contiguous) group of active subcarriers. The active subcarrier(s) may be surrounded by one or more nulled (i.e. transmitting no signal) subcarriers.

-The active PTRSs may be boosted in power. The PTRS power boost may be performed to compensate power in the nulled subcarriers. The power boost level may be determined based on nulling subcarriers.

-The number/location of nulled SC (subcarrier) may be chosen adaptively, as a non-limiting example, depending on the SC spacing and/or PN PSD bandwidth. More specifically, in such way that (i) the lager SCS, the less number of nulled SCs used, and/or (ii) the wider PN bandwidth (BW), the more nulled SCs used, but not limited thereto.

-The number/location of nulled SC may be chosen adaptively, as a non-limiting example, in such way that the total nulling area (resource), around of the pilot PT-RSs, covers the substantial part of the PN PSD BW.

-The PT-RS may be used at the RX device in combination with DM-RS at least for channel estimation, Doppler shift estimations and/or coherent OFDM symbol demodulation. For example, DL PT-RS may be transmitted along with DL DMRS and PDSCH (or PDCCH). UL PT-RS may be transmitted along with UL DMRS and PUSCH (or PUCCH).

FIG. 19 illustrates an example of DL PTRS according to an embodiment of present invention.

UE may receive configuration regarding the PTRS through RRC signaling (1505). The configuration may include one or more of the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R).

UE may receive DCI scheduling PDSCH (1510).

UE may determine information regarding the PTRS to be received along with the PDSCH, based on the configuration regarding the PTRS and the DCI (1520). For example, the UE can figure out the power and position, and number of the active PTRS/null SCs, based on the configuration regarding the PTRS and DCI indicating MCS to be applied to PDSCH and BW of PDSCH.

The BS may generate and map the PTRS (1540) as signaled by the configuration regarding the PTRS and the DCI.

The UE may receive (1550) the DL signal including the PTRS based on the information regarding the PTRS. PTRS may be used for PDSCH reception (e.g., channel estimation, demodulation).

FIG. 20 illustrates an example of UL PTRS according to an embodiment of present invention.

UE may receive configuration regarding the PTRS through RRC signaling (1605). The configuration may include one or more of the number of chunks (C), the size of 1 chunk (X), the distance between Chunks (D), the number of (minimum) null subcarriers required for active PTRS subcarriers per chunk (N), and/or PTRS-power boost level (R).

UE may receive DCI scheduling UL Signal (1610).

UE may generate/map the PTRS to be transmitted, based on the configuration regarding the PTRS and the DCI (1630). For example, the UE can determine the power and position, and number of the active PTRS/null SCs, based on the configuration regarding the PTRS and DCI indicating MCS to be applied to PUSCH/PUCCH and BW of PUSCH/PUCCH.

The UE may transmit the UL signal including the PTRS (1635).

Meanwhile, aforementioned higher frequency band such as 52.6 GHz to 71 GHz is one example of a frequency band where the present invention can be used, but this invention is not limited thereto. The frequency band where the present invention can be applied may be categorized as FR (frequency range) 3.

Also, aforementioned 'bandwidth' may refer to a frequency band including subcarriers (not limited to the size of the frequency band in the frequency domain). For example, the bandwidth may refer to a frequency band such as a bandwidth part, a component carrier and/or RBs.

According to an embodiment, a method of receiving a signal by a user equipment (UE) in a wireless communication system, may include receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); receiving downlink control information (DCI) scheduling DL data; and receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be received in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. And, the one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

A processor readable medium recorded thereon instruction for executing the method can be provided.

According to an embodiment, a device for processing a signal for wireless communication, may include a memory configured to store instructions; and a processor configured to perform operations, by executing the instructions. The operations may include an operation for receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); an operation for receiving downlink control information (DCI) scheduling DL data; and an operation for receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be received in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. And, the one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the downlink data as scheduled by the DCI. The device may further include a transceiver configured to transmit or receive signals under control of the processor. The device may be a user equipment (UE) configured to operate in a 3rd generation partnership project (3GPP)-based wireless communication system.

According to an embodiment, a method of transmitting a signal by a base station (BS) in a wireless communication system, may include transmitting, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); transmitting downlink control information (DCI) scheduling DL data; and transmitting in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. The one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

According to an embodiment, a base station (BS) for wireless communication, may include a transceiver; a memory configured to store instructions; and a processor configured to perform operations, by executing the instructions. The operations may include an operation for transmitting, via the transceiver through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS); an operation for transmitting, via the transceiver, downlink control information (DCI) scheduling DL data; and an operation for transmitting, via the transceiver, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS. The PTRS may be transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth. Each PTRS subcarrier group may include one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped. The one or more null PTRS subcarriers may be determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.

FIG. 21 illustrates a communication system 1 can be applied to the present disclosure.

Referring to FIG. 21, the communication system 1 applied to the present disclosure includes wireless devices, BSs, and a network. A wireless device is a device performing communication using radio access technology (RAT) (e.g., 5G NR (or New RAT) or LTE), also referred to as a communication/radio/5G device. The wireless devices may include, not limited to, a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an IoT device 100f, and an artificial intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of vehicle-to-vehicle (V2V) communication. Herein, the vehicles may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an augmented reality (AR)/virtual reality (VR)/mixed reality (MR) device and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) mounted in a vehicle, a television (TV), a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, and so on. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or smartglasses), and a computer (e.g., a laptop). The home appliance may include a TV, a refrigerator, a washing machine, and so on. The IoT device may include a sensor, a smartmeter, and so on. For example, the BSs and the network may be implemented as wireless devices, and a specific wireless device 200a may operate as a BS/network node for other wireless devices.

The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200/network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without intervention of the BSs/network. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g. V2V/vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

Wireless communication/connections 150a, 150b, and 150c may be established between the wireless devices 100a to 100f/BS 200 and between the BSs 200. Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as UL/DL communication 150a, sidelink communication 150b (or, D2D communication), or inter-BS communication (e.g. relay or integrated access backhaul(IAB)). Wireless signals may be transmitted and received between the wireless devices, between the wireless devices and the BSs, and between the BSs through the wireless communication/connections 150a, 150b, and 150c. For example, signals may be transmitted and receive don various physical channels through the wireless communication/connections 150a, 150b and 150c. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocation processes, for transmitting/receiving wireless signals, may be performed based on the various proposals of the present disclosure.

FIG. 20 illustrates wireless devices applicable to the present disclosure.

Referring to FIG. 20, a first wireless device 100 and a second wireless device 200 may transmit wireless signals through a variety of RATs (e.g., LTE and NR). {The first wireless device 100 and the second wireless device 200} may correspond to {the wireless device 100x and the BS 200} and/or {the wireless device 100x and the wireless device 100x} of FIG. 21.

The first wireless device 100 may include one or more processors 102 and one or more memories 104, and further include one or more transceivers 106 and/or one or more antennas 108. The processor(s) 102 may control the memory(s) 104 and/or the transceiver(s) 106 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. For example, the processor(s) 102 may process information in the memory(s) 104 to generate first information/signals and then transmit wireless signals including the first information/signals through the transceiver(s) 106. The processor(s) 102 may receive wireless signals including second information/signals through the transceiver(s) 106 and then store information obtained by processing the second information/signals in the memory(s) 104. The memory(s) 104 may be connected to the processor(s) 102 and may store various pieces of information related to operations of the processor(s) 102. For example, the memory(s) 104 may store software code including instructions for performing all or a part of processes controlled by the processor(s) 102 or for performing the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. The processor(s) 102 and the memory(s) 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connected to the processor(s) 102 and transmit and/or receive wireless signals through the one or more antennas 108. Each of the transceiver(s) 106 may include a transmitter and/or a receiver. The transceiver(s) 106 may be interchangeably used with radio frequency (RF) unit(s). In the present disclosure, the wireless device may be a communication modem/circuit/chip.

The second wireless device 200 may include one or more processors 202 and one or more memories 204, and further include one or more transceivers 206 and/or one or more antennas 208. The processor(s) 202 may control the memory(s) 204 and/or the transceiver(s) 206 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. For example, the processor(s) 202 may process information in the memory(s) 204 to generate third information/signals and then transmit wireless signals including the third information/signals through the transceiver(s) 206. The processor(s) 202 may receive wireless signals including fourth information/signals through the transceiver(s) 106 and then store information obtained by processing the fourth information/signals in the memory(s) 204. The memory(s) 204 may be connected to the processor(s) 202 and store various pieces of information related to operations of the processor(s) 202. For example, the memory(s) 204 may store software code including instructions for performing all or a part of processes controlled by the processor(s) 202 or for performing the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. The processor(s) 202 and the memory(s) 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 206 may be connected to the processor(s) 202 and transmit and/or receive wireless signals through the one or more antennas 208. Each of the transceiver(s) 206 may include a transmitter and/or a receiver. The transceiver(s) 206 may be interchangeably used with RF unit(s). In the present disclosure, the wireless device may be a communication modem/circuit/chip.

Now, hardware elements of the wireless devices 100 and 200 will be described in greater detail. One or more protocol layers may be implemented by, not limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as physical (PHY), medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), RRC, and service data adaptation protocol (SDAP)). The one or more processors 102 and 202 may generate one or more protocol data units (PDUs) and/or one or more service data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document and provide the messages, control information, data, or information to one or more transceivers 106 and 206. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document may be included in the one or more processors 102 and 202 or may be stored in the one or more memories 104 and 204 and executed by the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of code, an instruction, and/or a set of instructions.

The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or more memories 104 and 204 may be configured to include read-only memories (ROMs), random access memories (RAMs), electrically erasable programmable read-only memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories 104 and 204 may be located at the interior and/or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, control information, and/or wireless signals/channels, mentioned in the methods and/or operation flowcharts of this document, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and/or wireless signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive wireless signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or wireless signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or wireless signals from one or more other devices. The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208 and the one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and/or wireless signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document, through the one or more antennas 108 and 208. In this document, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). The one or more transceivers 106 and 206 may convert received wireless signals/channels from RF band signals into baseband signals in order to process received user data, control information, and wireless signals/channels using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, and wireless signals/channels processed using the one or more processors 102 and 202 from the baseband signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and/or filters.

FIG. 23 illustrates another example of a wireless device applied to the present disclosure. The wireless device may be implemented in various forms according to a use case/service (refer to FIG. 21).

Referring to FIG. 23, wireless devices 100 and 200 may correspond to the wireless devices 100 and 200 of FIG. 21 and may be configured to include various elements, components, units/portions, and/or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit 110 may include a communication circuit 112 and transceiver(s) 114. For example, the communication circuit 112 may include the one or more processors 102 and 202 and/or the one or more memories 104 and 204 of FIG. 20. For example, the transceiver(s) 114 may include the one or more transceivers 106 and 206 and/or the one or more antennas 108 and 208 of FIG. 20. The control unit 120 is electrically connected to the communication unit 110, the memory 130, and the additional components 140 and provides overall control to the wireless device. For example, the control unit 120 may control an electric/mechanical operation of the wireless device based on programs/code/instructions/information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the outside (e.g., other communication devices) via the communication unit 110 through a wireless/wired interface or store, in the memory unit 130, information received through the wireless/wired interface from the outside (e.g., other communication devices) via the communication unit 110.

The additional components 140 may be configured in various manners according to type of the wireless device. For example, the additional components 140 may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, not limited to, the robot (100a of FIG. 21), the vehicles (100b-1 and 100b-2 of FIG. 21), the XR device (100c of FIG. 21), the hand-held device (100d of FIG. 21), the home appliance (100e of FIG. 21), the IoT device (100f of FIG. 21), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a FinTech device (or a finance device), a security device, a climate/environment device, the AI server/device (400 of FIG. 21), the BSs (200 of FIG. 21), a network node, or the like. The wireless device may be mobile or fixed according to a use case/service.

In FIG. 23, all of the various elements, components, units/portions, and/or modules in the wireless devices 100 and 200 may be connected to each other through a wired interface or at least a part thereof may be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected by wire and the control unit 120 and first units (e.g., 130 and 140) may be wirelessly connected through the communication unit 110. Each element, component, unit/portion, and/or module in the wireless devices 100 and 200 may further include one or more elements. For example, the control unit 120 may be configured with a set of one or more processors. For example, the control unit 120 may be configured with a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphical processing unit, and a memory control processor. In another example, the memory 130 may be configured with a RAM, a dynamic RAM (DRAM), a ROM, a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

FIG. 24 illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. The vehicle or autonomous driving vehicle may be implemented as a mobile robot, a car, a train, a manned/unmanned aerial vehicle (AV), a ship, or the like.

Referring to FIG. 24, a vehicle or autonomous driving vehicle 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a driving unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d. The antenna unit 108 may be configured as a part of the communication unit 110. The blocks 110/130/140a to 140d correspond to the blocks 110/130/140 of FIG. 23, respectively.

The communication unit 110 may transmit and receive signals (e.g., data and control signals) to and from external devices such as other vehicles, BSs (e.g., gNBs and road side units), and servers. The control unit 120 may perform various operations by controlling elements of the vehicle or the autonomous driving vehicle 100. The control unit 120 may include an ECU. The driving unit 140a may enable the vehicle or the autonomous driving vehicle 100 to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, and so on. The power supply unit 140b may supply power to the vehicle or the autonomous driving vehicle 100 and include a wired/wireless charging circuit, a battery, and so on. The sensor unit 140c may acquire information about a vehicle state, ambient environment information, user information, and so on. The sensor unit 140c may include an inertial measurement unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, and so on. The autonomous driving unit 140d may implement technology for maintaining a lane on which the vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a route if a destination is set, and the like.

For example, the communication unit 110 may receive map data, traffic information data, and so on from an external server. The autonomous driving unit 140d may generate an autonomous driving route and a driving plan from the obtained data. The control unit 120 may control the driving unit 140a such that the vehicle or autonomous driving vehicle 100 may move along the autonomous driving route according to the driving plan (e.g., speed/direction control). During autonomous driving, the communication unit 110 may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. During autonomous driving, the sensor unit 140c may obtain information about a vehicle state and/or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving route and the driving plan based on the newly obtained data/information. The communication unit 110 may transfer information about a vehicle position, the autonomous driving route, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology based on the information collected from vehicles or autonomous driving vehicles and provide the predicted traffic information data to the vehicles or the autonomous driving vehicles.

The embodiments of the present disclosure described above are combinations of elements and features of the present disclosure. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, an embodiment of the present disclosure may be constructed by combining parts of the elements and/or features. Operation orders described in embodiments of the present disclosure may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. It is obvious to those skilled in the art that claims that are not explicitly cited in each other in the appended claims may be presented in combination as an embodiment of the present disclosure or included as a new claim by a subsequent amendment after the application is filed.

The embodiments of the present disclosure have been described above, focusing on the signal transmission and reception relationship between a UE and a BS. The signal transmission and reception relationship is extended to signal transmission and reception between a UE and a relay or between a BS and a relay in the same manner or a similar manner. A specific operation described as performed by a BS may be performed by an upper node of the BS. Namely, it is apparent that, in a network comprised of a plurality of network nodes including a BS, various operations performed for communication with a UE may be performed by the BS, or network nodes other than the BS. The term BS may be replaced with the term fixed station, Node B, enhanced Node B (eNode B or eNB), access point, and so on. Further, the term UE may be replaced with the term terminal, mobile station (MS), mobile subscriber station (MSS), and so on.

Those skilled in the art will appreciate that the present disclosure may be carried out in other specific ways than those set forth herein without departing from the spirit and essential characteristics of the present disclosure. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the disclosure should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

The present disclosure may be used in a UE, a BS, or other devices in a mobile communication system.

Claims

A method of receiving a signal by a user equipment (UE) in a wireless communication system, the method comprising:

receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS);

receiving downlink control information (DCI) scheduling DL data; and

receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS,

wherein the PTRS is received in one or more PTRS subcarrier groups within the specific scheduled bandwidth,

wherein each PTRS subcarrier group includes one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped, and

wherein the one or more null PTRS subcarriers are determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.
The method according to claim 1,

wherein the one or more PTRS subcarrier groups include a first PTRS subcarrier group and a second PTRS subcarrier group which are apart from each other in a frequency domain, and

where a distance between the first PTRS subcarrier group and the second PTRS subcarrier group is determined based on a size of the specific scheduled bandwidth.
The method according to claim 1, wherein the one or more active PTRS subcarriers are power boosted based on freed power from the one or more null PTRS subcarriers.
The method according to claim 1, wherein the configuration regarding the PTRS include information regarding at least one of a number of the one or more PTRS subcarrier groups, a size of 1-PTRS subcarrier group, a distance between neighboring PTRS subcarrier groups, a number of the null PTRS subcarriers per 1-PTRS subcarrier group, or at least one power boost level for the one or more active PTRS subcarriers.
The method according to claim 1, wherein the DCI includes information regarding a power boost level applied to the one or more active PTRS subcarriers from among one or more power boost levels configured through the configuration regarding the PTRS.
The method according to claim 1,

wherein the one or more active PTRS subcarriers locate at a center of each PTRS subcarrier group through localized mapping; and

wherein the one or more null subcarriers locate at edges of each PTRS subcarrier group.
The method according to claim 1, wherein less null PTRS subcarriers are used for lager SCS, and more null PTRS subcarriers are used for a wider phase noise bandwidth.
The method according to claim 1, wherein a number of the one or more null PTRS subcarriers satisfies a formula floor{(X-1)/2}, where 'X' denotes a total number of subcarriers per 1-PTRS subcarrier group.
The method according to claim 1, wherein the one or more active PTRS subcarriers are power boosted based a ratio of X/(X-N), where 'X' denotes a total number of subcarriers per 1-PTRS subcarrier group, and 'N' denotes a number of null PTRS subcarriers per 1-PTRS subcarrier group.
The method according to claim 1, wherein the DCI is received through a physical downlink control channel (PDCCH), the DL data is received through a physical downlink shared channel (PDSCH), and the DL signal includes the PDSCH and a demodulation reference signal (DMRS) for the PDSCH.
A processor readable medium recorded thereon instruction for executing the method of claim 1.
A device for processing a signal for wireless communication, the device comprising:

a memory configured to store instructions; and

a processor configured to perform operations, by executing the instructions, the operations comprising:

an operation for receiving, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS);

an operation for receiving downlink control information (DCI) scheduling DL data; and

an operation for receiving, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS,

wherein the PTRS is received in one or more PTRS subcarrier groups within the specific scheduled bandwidth,

wherein each PTRS subcarrier group includes one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped, and

wherein the one or more null PTRS subcarriers are determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the downlink data as scheduled by the DCI.
The device according to claim 12, further comprising:

a transceiver configured to transmit or receive signals under control of the processor, and

wherein the device is a user equipment (UE) configured to operate in a 3rd generation partnership project (3GPP)-based wireless communication system.
A method of transmitting a signal by a base station (BS) in a wireless communication system, the method comprising:

transmitting, through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS);

transmitting downlink control information (DCI) scheduling DL data; and

transmitting in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS,

wherein the PTRS is transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth,

wherein each PTRS subcarrier group includes one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped, and

wherein the one or more null PTRS subcarriers are determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.
A base station (BS) for wireless communication, the BS comprising:

a transceiver;

a memory configured to store instructions; and

a processor configured to perform operations, by executing the instructions, the operations comprising:

an operation for transmitting, via the transceiver through higher layer signaling, configuration regarding a phase tracking reference signal (PTRS);

an operation for transmitting, via the transceiver, downlink control information (DCI) scheduling DL data; and

an operation for transmitting, via the transceiver, in a specific scheduled bandwidth, a DL signal including the DL data and the PTRS based on the DCI and the configuration regarding the PTRS,

wherein the PTRS is transmitted in one or more PTRS subcarrier groups within the specific scheduled bandwidth,

wherein each PTRS subcarrier group includes one or more active PTRS subcarriers to which a PTRS sequence is mapped and one or more null PTRS subcarriers to which the PTRS sequence is not mapped, and

wherein the one or more null PTRS subcarriers are determined based on at least one of subcarrier spacing (SCS), and modulation and coding scheme (MCS) for the DL data as scheduled by the DCI.