KR20210020832A - Power control method, device and storage medium for sidelink communication system - Google Patents

Abstract

Disclosed are a communication technology for fusing an Internet of things (IoT) technology and a fifth-generation (5G) communication system for supporting a higher data transmission rate after a fourth-generation (4G) system and a system thereof. The present invention can be applied to an intelligent service (for example, a service related to a smart home, a smart building, a smart city, a smart of connected car, healthcare, digital education, retail sales, security, safety, and the like) based on a 5G communication technology and an IoT-related technology. According to one aspect of the present invention, a method for a first terminal of a communication system comprises the following steps of: transmitting sidelink control information (SCI) including an information field related to a request for sidelink channel state information (CSI) to a second terminal; transmitting a sidelink channel state information reference signal (CSI-RS) to the second terminal in response to the information field indicating a request for the sidelink CSI; and receiving the sidelink CSI acquired based on the sidelink CSI-RS from the second terminal.

Description

Power control method, device and storage medium for sidelink communication system {POWER CONTROL METHOD, DEVICE AND STORAGE MEDIUM FOR SIDELINK COMMUNICATION SYSTEM}

The present disclosure relates to communication technology, and in particular, to a power control method for NR V2X in a communication system.

Efforts are being made to develop an improved 5G communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of 4G communication systems. For this reason, a 5G communication system or a pre-5G communication system is called a Beyond 4G Network communication system or an LTE system and a Post LTE system. In order to achieve a high data rate, the 5G communication system is being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Giga (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, in order to improve the network of the system, in 5G communication system, advanced small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation And other technologies are being developed. In addition, in the 5G system, advanced coding modulation (ACM) methods such as Hybrid FSK and QAM Modulation (FQAM) and SWSC (Sliding Window Superposition Coding), advanced access technologies such as Filter Bank Multi Carrier (FBMC), NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) have been developed.

On the other hand, the Internet is evolving from a human-centered network in which humans generate and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are implemented by techniques such as beamforming, MIMO, and array antenna. There is. As the big data processing technology described above, a cloud radio access network (cloud RAN) is applied as an example of the convergence of 5G technology and IoT technology.

In the 3GPP LTE standard, a direct communication link between a user equipment (UE) and another UE is called a sidelink (SL). Similar to the downlink (DL) and uplink (UL), the control channel(s) and data channel(s) are also present on the SL, the former being called the Physical Sidelink Control Channel (PSCCH). The latter is called a Physical Sidelink Shared Channel (PSSCH). The PSCCH is used to indicate information about time domain and frequency domain resource locations, modulation and coding schemes, etc. of PSSCH transmission, and the PSSCH is used to carry data.

In the 3GPP 5G New Radio (NR) system, V2X is one of the working items (WI) of the Rel-16 NR standard. In the NR V2X system, in order to support more types of data services, sidelink communication is added to the broadcast transmission, and groupcast transmission (i.e., the sidelink physical channel transmitted by the UE is Received and decoded) and unicast transmission (i.e., the sidelink physical channel transmitted by the UE is received and decoded by another UE within a certain range) also needs to be supported. In order to reduce interference between UEs in a sidelink system, both groupcast and unicast transmissions can support calculation of transmit power based on sidelink path loss between two UEs, but no specific solution has been proposed.

The present disclosure primarily proposes a corresponding solution(s) to one or more technical problems mentioned above.

In order to overcome the above technical problems or at least partially solve the above technical problems, the following technical solutions are proposed:

According to an aspect of the present disclosure, a method of a first terminal of a communication system is provided, the method comprising sidelink control information (SCI) including an information field related to a request for sidelink channel state information (CSI). : transmitting sidelink control information) to a second terminal; Transmitting a sidelink channel state information reference signal (CSI-RS) to the second terminal in response to the information field indicating a request for a sidelink CSI; And receiving a sidelink CSI obtained based on the sidelink CSI-RS from the second terminal.

Preferably, the sidelink CSI is characterized in that it is received through a medium access control (MAC) control element (CE).

Preferably, the priority of the MAC CE is characterized in that a predefined value.

Preferably, the sidelink CSI is characterized in that it includes a rank indicator (RI) and channel quality information (CQI) excluding a precoding matrix indicator (PMI).

According to another aspect of the present disclosure, a method of a second terminal of a communication system is provided, the method comprising sidelink control information including an information field related to a request for sidelink channel state information (CSI) ( SCI: receiving sidelink control information) from the first terminal; Receiving a sidelink channel state information reference signal (CSI-RS) from the first terminal in response to the information field indicating a request for a sidelink CSI; And transmitting the sidelink CSI obtained based on the sidelink CSI-RS to the first terminal.

According to another aspect of the present disclosure, a first terminal of a communication system is provided, and the first terminal includes: a transceiver; And sidelink control information (SCI: sidelink control information) including an information field related to a request for sidelink channel state information (CSI) is transmitted to the second terminal, and the information field is a sidelink CSI request In response to the indication, a sidelink channel state information reference signal (CSI-RS) is transmitted to the second terminal, and the sidelink CSI obtained based on the sidelink CSI-RS is transmitted to the second terminal. It may include a control unit configured to receive from the second terminal.

According to another aspect of the present disclosure, a second terminal of a communication system is provided, and the second terminal includes: a transceiver; And sidelink control information (SCI) including an information field related to a request for sidelink channel state information (CSI) from the first terminal, and the information field is a request for sidelink CSI In response to indicating, a sidelink channel state information reference signal (CSI-RS) is received from the first terminal, and the sidelink CSI obtained based on the sidelink CSI-RS is received. It may include a control unit configured to transmit to the first terminal.

By the above-described method, the UE and the storage medium, the transmit power of the sidelink transmission between the two UEs can be effectively calculated based on the sidelink path loss between the two UEs.

The above and/or additional aspects and advantages of the present invention will become apparent and easy to understand from the description of the following embodiments with the accompanying drawings.
1 is a flowchart of a power control method for a sidelink communication system according to an embodiment of the present disclosure.
2 is a diagram illustrating a structure of a MAC SE for indicating L1-RSRP according to an embodiment of the present disclosure.
3A to 3C are diagrams of a structure of a MAC SE for indicating L1-RSRP of a plurality of slots according to an embodiment of the present disclosure.
4 is a flowchart illustrating a power control method for a sidelink communication system according to another embodiment of the present disclosure.
5A to 5C are diagrams of a pattern design for a CSI-RS according to an embodiment of the present disclosure.
6 is a flowchart illustrating a power control method for a sidelink communication system according to another embodiment of the present disclosure.
7 is a flowchart illustrating a sidelink communication system for measuring/feeding back sidelink channel state information according to another embodiment of the present disclosure.
8 shows a diagram of a time window for SL CSI feedback according to an embodiment of the present disclosure.
9A to 9B are diagrams for determining a measurement slot position corresponding to SL CSI feedback according to an embodiment of the present disclosure.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings in which embodiments of the present invention are shown, wherein the same or similar reference numerals throughout the drawings refer to the same or similar elements or elements having the same or similar functions. do. The embodiments described later in connection with the drawings are merely illustrative, and are only for describing the present invention, and are not intended to limit the present invention.

As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. The terms “consist of” and/or “consisting of” or “comprising” and/or “comprising”, as used herein, refer to the mentioned feature(s), integer(s), step(s), To specify the presence of an action(s), element(s), and/or component(s), but one or more other features, integers, steps, actions, elements, components, and/or their It will also be understood that the presence or addition of groups is not excluded. When an element is referred to as being “connected” or “coupled” to another element, it will be understood that it may be directly connected or coupled to the other element or that intervening elements may exist between them. In addition, "connection" or "coupling" as used herein may include wireless connection or wireless coupling. The term “and/or” as used herein includes one or all of the listed one or more related items and all combinations thereof.

Those skilled in the art can understand that unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms, such as terms defined in a commonly used dictionary, should be understood as having a meaning consistent with their meaning in the context of the related art and the present disclosure, and unless explicitly defined in the present specification, it is ideal or overly formal. It will be understood that it is not interpreted in meaning.

"Terminal" and "terminal equipment" as used herein are not only a wireless signal receiver device, which is a device having only a wireless signal receiver without transmission capability, but also a device having reception and transmission hardware capable of performing two-way communication through a two-way communication link. It will be appreciated by those skilled in the art that it includes an apparatus with phosphor receiving and transmitting hardware. Such a device may be a cellular or other communication device with a single line display or a multiple line display or a cellular or other communication device without a multiple line display; Personal Communication Services (PCS), which may be a combination of voice, data processing, fax and/or data communication functions; PDA (Personal Digital Assistant), which may include a radio frequency receiver, pager, Internet/Intranet access, web browser, notes, calendar, and/or Global Positioning System (GPS) receiver; It may include a conventional laptop and/or handheld computer or other device with and/or including a radio frequency receiver. As used herein, "terminal", "terminal equipment" may be portable, transportable, vehicle (air, sea and/or land) installation type, or may be adapted and/or configured to operate locally and/or It can operate in a distributed form on Earth and/or other places in space. "Terminal" and "terminal equipment" as used herein may also be a communication terminal, an Internet terminal, an audio/video playback terminal, for example, this may be a PDA, a Mobile Internet Device (MID) and/or an audio/video playback It could be a mobile phone with functionality, or a smart TV, a set-top box, and other devices.

Two sidelink communication mechanisms: device-to-device (D2D) communication and sidelink-based vehicle-to-vehicle/pedestrian/infrastructure/network (hereinafter simply referred to as V2X) are defined in the 3GPP LTE standard. The latter has become the most common sidelink communication technology in the current 3GPP LTE standard because it is superior to the former in terms of data rate, time delay, and reliability.

From the point of view of the resource allocation mechanism, the current LTE V2X technology has a total of two modes, namely a sidelink resource allocation mode (mode 3) based on base station scheduling referred to as centralized communication, and autonomous selection of the UE referred to as distributed communication. Includes the dependent sidelink resource allocation mode (mode 4). Regarding mode 3, the UE determines sidelink resources for sidelink channel communication allocated by the base station by receiving the downlink control channel of the base station, and sidelinks for different UEs according to the base station's rational scheduling strategy. Mutual interference between resources can be minimized. Regarding mode 4, the base station is not involved in specific sidelink resource allocation, and the UE determines available sidelink resources by sensing sidelink channels. When the existing LTE V2X technology was initially designed, it was mainly used to support broadcast transmissions, so the current mode 3 and mode 4 use broadcast transmission at the physical layer, that is, the sidelink physical channel transmitted by the UE. Is received and decoded by all UEs within a certain range. In addition, for UEs in coverage (IC), both mode 3 and mode 4 transmissions support power control, and based on downlink path loss between the UE and the base station of the cell in which the UE is camped. The transmit power is calculated.

Some specific embodiments will be described below. In the following embodiments, a UE that transmits a sidelink physical data channel is simply referred to as a transmitting UE (TX UE), and a UE that receives a sidelink physical data channel is simply referred to as a receiving UE (RX UE).

In Examples 1 and 2, the RX UE measures the layer 1 (L1) Reference Signal Received Power (RSRP) based on the reference signal (RS) transmitted by the TX UE, and the measured L1 -RSRP is fed back to the TX UE. The TX UE generates a layer L3 (L3) RSRP based on the L1-RSRP received through upper layer filtering, and the TX UE and the RX UE based on the generated L3-RSRP and the transmission power of the RS for RSRP measurement. Calculate the sidelink pathloss between. That is, the TX UE is a performer for generating the L3-RSRP, and is also a performer for calculating the sidelink path loss between the TX UE and the RX UE.

In Example 2, the RX UE measures L1-RSRP based on the RS transmitted by the TX UE, generates L3-RSRP through upper layer filtering based on the measured L1-RSRP, and also generates L3-RSRP. RSRP is fed back to the TX UE. Thereafter, the TX UE calculates the sidelink path loss between the TX UE and the RX UE based on the received L3-RSRP and the transmit power of the RS for RSRP measurement. That is, the RX UE is an performer for generating the L3-RSRP, and the TX UE is an performer for calculating the sidelink path loss between the TX UE and the RX UE.

In embodiment 3, the TX UE signals the transmit power of the RS for RSRP measurement to the RX UE. RX UE measures L1-RSRP based on the RS transmitted by the TX UE, generates L3-RSRP through upper layer filtering based on the measured L1-RSRP, and measures the generated L3-RSRP and the received RSRP The sidelink path loss between the TX UE and the RX UE is calculated based on the transmission power of the RS for, and the calculated sidelink path loss is fed back to the TX UE. That is, the RX UE is a performer for generating L3-RSRP, and is also a performer for calculating sidelink path loss between the TX UE and the RX UE.

L1-RSRP is the reference signal received power measured at the physical layer, and since it is affected by both large-scale fading and small-scale fading, it cannot be used to directly estimate path loss. The physical layer must report the measured L1-RSRP to an upper layer (Radio Resource Control (RRC) layer), and this upper layer filters the measured L1-RSRPs within a predetermined time to generate L3-RSRP. RSRP upper layer filtering can be understood as a sliding average of L1-RSRPs measured within a certain period of time to compensate for the effect of small-scale fading, and therefore, L3-RSRP generated after filtering includes only the effect of large-scale fading. do. Therefore, only L3-RSRP can be used for path loss calculation. L1-RSRP may be simply referred to as physical layer RSRP, and L3-RSRP may simply be referred to as higher layer RSRP or RRC layer RSRP.

Example 1: The RX UE feeds back L1-RSRP to the TX UE, and the TX UE generates L3-RSRP based on the received L1-RSRP.

In Embodiment 1, the RSRP fed back to the TX UE by the RX UE is L1-RSRP, that is, the TX UE is a performer for generating L3-RSRP by performing RSRP higher layer filtering. The RX UE measures RSRP based on the RS transmitted by the TX UE, and feeds back the measured L1-RSRP to the TX UE. The TX UE reports the received L1-RSRP to the upper layer, and the L3-RSRP is generated through upper layer filtering of the L1-RSRP. The TX UE calculates the sidelink path loss between the TX UE and the RX UE based on the generated L3-RSRP and the transmission power of the RS for RSRP measurement. In particular, as shown in Fig. 1, Embodiment 1 includes the following steps.

In step S110, the TX UE transmits signaling for triggering feedback of L1-RSRP to the RX UE.

In step S120, the RX UE measures L1-RSRP based on the RS transmitted by the TX UE, and feeds back the measured L1-RSRP to the TX UE. In particular, after receiving the signaling for triggering feedback of L1-RSRP, the RX UE measures L1-RSRP based on the RS transmitted by the TX UE, and feeds back the measured L1-RSRP to the TX UE.

In step S130, the TX UE reports the received L1-RSRP to an upper layer, and generates an L3-RSRP through RSRP upper layer filtering. In particular, after receiving the fed back L1-RSRP, the TX UE reports the L1-RSRP to the upper layer, and generates the L3-RSRP by RSRP upper layer filtering of the L1-RSRPs received within a predetermined time.

In step S130, when the TX UE is in coverage (IC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the TX UE is UE-specific by the serving base station of the cell where the TX UE is located. Pre-configured through RRC signaling; When the TX UE is out of coverage (OOC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the TX UE is hard-coded through the sidelink higher layer parameter. Pre-configured.

In step S140, the TX UE calculates a sidelink path loss between the TX UE and the RX UE based on the transmission power of the RS for measuring the L3-RSRP and RSRP generated in step S130.

In step S150, the TX UE calculates the transmit power based on the sidelink path loss calculated in step S140, and applies the calculated transmit power to the sidelink transmission to the RX UE. Here, the sidelink transmission is PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), Sidelink Channel Information Reference Signal (SL CSI-RS) and/or sidelink phase tracking reference Signal (Sidelink Phase Tracking Reference Signal, SL PTRS), etc.

Optionally, step S110 may be omitted. For example, when power control based on sidelink path loss is configured, after the sidelink RRC connection between the TX UE and the RX UE is established, the RX UE releases the sidelink RRC connection between the TX UE and the RX UE. L1-RSRP should continue to be fed back to the TX UE until it becomes available. Thereby, signaling overhead for establishing a sidelink transmission between the TX UE and the RX UE can be reduced, thereby improving communication efficiency.

In the power control method of the existing systems, the transmission power of a reference signal for measuring RSRP for power control purposes is not changed. For example, in the LTE system, the transmission power of the CRS for RSRP measurement does not change, the LTE base station can notify the UE of the transmission power of the CRS, and the UE is between the transmission power of the CRS and the corresponding generated L3-RSRP. The difference is determined as the downlink path loss. In the NR system, the transmission powers of SSB and CSI-RS for RSRP measurement do not change, the NR base station signals the transmission powers of SSB and CSI-RS to the UE, and the UE corresponds to the transmission power of SSB/CSI-RS. The difference between the generated L3-RSRP is determined as the downlink path loss.

In conclusion, the transmit power of the RS based on L1-RSRP (ie, L1-RSRPs measured within a predetermined time) for generating L3-RSRP should not generally change. When the transmission power of the RS is changed, the performer who generates the L3-RSRP must know the change amount of the transmission power of the RS, compensates the change amount for the corresponding measured L1-RSRP, and then increases the compensated L1-RSRP. It is reported to the layer, thereby ensuring that transmission powers based on L1-RSRPs measured within a predetermined time to generate L3-RSRP are equally equal.

In Embodiment 1, since both the performer for RS transmission and the performer for L3-RSRP generation are TX UEs, there is no need to maintain a state in which the transmission power of the RS for RSRP measurement is not changed. Since the TX UE knows the amount of change in the transmission power of the RS, it can compensate the corresponding measured L1-RSRP. However, in this case, the TX UE must accurately know the slot location where the corresponding RS for RSRP measurement is located for each L1-RSRP fed back by the RX UE, thereby accurately knowing the transmission power of the corresponding RS. I can.

Periodic/semi-continuous L1-RSRP feedback

Since L3-RSRP is generated based on a plurality of L1-RSRP samples within a predetermined time, preferably, the TX UE should trigger periodic L1-RSRP feedback by sending signaling to the RX UE, and the RX UE should trigger this signaling. After receiving the L1-RSRP should be periodically fed back to the TX UE.

The TX UE may trigger periodic L1-RSRP feedback by the RX UE through explicit signaling. For example, the TX UE transmits sidelink RRC signaling to the RX UE to trigger (configure) periodic L1-RSRP feedback. Alternatively, the TX UE transmits sidelink RRC signaling to the RX UE to configure a plurality of period values of the L1-RSRP feedback, and transmits MAC CE signaling to the RX UE, so that among a plurality of period values of the L1-RSRP feedback. Trigger one and periodic L1-RSRP feedback. To distinguish between periodic L1-RSRP feedback triggered by MAC CE signaling and periodic L1-RSRP feedback triggered by sidelink RRC signaling, the former is referred to as semi-persistent L1-RSRP feedback, and the latter is periodic L1-RSRP feedback. And the difference is the way that triggers signaling. The system may support periodic L1-RSRP feedback and/or semi-persistent L1-RSRP feedback. After receiving the trigger (configuration) signaling for the periodic L1-RSRP feedback, the RX UE periodically performs the L1-RSRP feedback until it receives the corresponding sidelink RRC or MAC CE signaling for terminating the periodic L1-RSRP feedback. Should be done.

The TX UE may also trigger periodic L1-RSRP feedback by the RX UE via implicit signaling. For example, when power control based on sidelink path loss is configured, after the sidelink RRC connection between the TX UE and the RX UE is established, the RX UE releases the sidelink RRC connection between the TX UE and the RX UE. Periodic L1-RSRP feedback is performed.

Optionally, a period value of the L1-RSRP feedback may be configured, and the TX UE configures values including the period of the L1-RSRP feedback through sidelink RRC signaling. Optionally, the period value of the L1-RSRP feedback is determined in advance by the system, and accordingly, signaling overhead between the TX UE and the RX UE can be reduced.

Optionally, the RS for RSRP measurement is periodically transmitted by the TX UE, and the TX UE signals the period of the RS to the RX UE, and the system sets the value of the period in which the RX UE feeds back L1-RSRP by the TX UE. It is assumed that it is designated to be the same as the period values of RS for measuring transmitted RSRP. That is, explicit signaling for configuring the period of the L1-RSRP feedback is not required, and thus, signaling overhead between the TX UE and the RX UE is reduced.

Optionally, the RS for RSRP measurement is periodically transmitted by the TX UE, and the system ensures that the value of the period at which the RX UE feeds back L1-RSRP feedback is greater than or equal to the period value of the RS for RSRP measurement transmitted by the TX UE. It is assumed to be specified. That is, explicit signaling is required to configure the period of the L1-RSRP feedback.

When the RS for RSRP measurement transmitted by the TX UE is periodic and the value of the period for the RX UE to feed back L1-RSRP is greater than the period value of the RS for RSRP measurement transmitted by the TX UE, or by the TX UE When the RS for the transmitted RSRP measurement is aperiodic, the RX UE may receive RSs for RSRP measurement that are transmitted several times by the TX UE during one period before the L1-RSRP feedback slot, after which the RX UE RSRP can be fed back in any of the following ways.

Method 1: The RX UE feeds back the L1-RSRP measured on the RS of the nearest one slot before the L1-RSRP feedback slot and within a predetermined gap to the TX UE.

Method 2: Based on the time point at which the RX UE feeds back any one of L1-RSRPs measured on a plurality of RSs before the L1-RSRP feedback slot and within a predetermined gap, and feeds back L1-RSRP, the L1- RSRP indicates the measured slot RS.

Method 3: The RX UE feeds back the average of L1-RSRPs measured on all RSs before the L1-RSRP feedback slot and within a predetermined gap to the TX UE.

Method 4: The RX UE feeds back all L1-RSRPs measured on all RSs before the L1-RSRP feedback slot and within a predetermined gap to the TX UE.

Here, the predetermined gap is for preparation of L1-RSRP feedback.

It is assumed that the RS for RSRP measurement transmitted by the TX UE is aperiodic and it cannot be guaranteed that the RS for RSRP measurement is transmitted at least once during each L1-RSRP feedback period. If the RX UE fails to receive the RS for RSRP measurement transmitted by the TX UE during one period prior to the L1-RSRP feedback slot, the RX UE cannot measure L1-RSRP, and at this time, the L1-RSRP feedback will be skipped. I can. That is, the aforementioned periodic L1-RSRP feedback may not be absolutely continuous periodic L1-RSRP feedback, but may be intermittent periodic L1-RSRP feedback.

In mode 1 based on centralized communication in NR V2X, transmission resources for PSCCH/PSSCH are evenly allocated by the base station. When the RX UE performs periodic L1-RSRP feedback, the RX UE requests periodic sidelink resources for L1-RSRP feedback from the serving base station of the cell in which it is located, and the base station requests periodic sidelink resources for L1-RSRP feedback of the RX UE. Sidelink resources can be allocated. Alternatively, the TX UE requests periodic sidelink resources for L1-RSRP feedback of the RX UE to the serving base station of the cell in which it is located, and periodic sidelink resources for L1-RSRP feedback of the RX UE allocated by the base station Signals to the RX UE.

In mode 2 based on distributed communication in NR V2X, transmission resources for PSCCH/PSSCH are autonomously allocated by the UE, and the UE autonomously selects available sidelink resources by channel sensing. When the RX UE performs periodic L1-RSRP feedback, if the RX UE selects one available sidelink resource for L1-RSRP transmission, sidelink resources may be periodically reserved for subsequent L1-RSRP feedbacks. . That is, the RX UE periodically reserves the same sidelink resource according to the value of the L1-RSRP feedback period. Alternatively, the TX UE periodically reserves the same sidelink resource for L1-RSRP feedback of the RX UE, and signals the periodic sidelink resource reserved for L1-RSRP feedback of the RX UE to the RX UE.

Aperiodic (one-shot) L1-RSRP feedback

As a supplement to periodic L1-RSRP feedback, the system may also support aperiodic L1-RSRP feedback. Here, the aperiodic L1-RSRP feedback means one-shot L1-RSRP feedback. That is, the TX UE triggers the one-shot L1-RSRP feedback of the RX UE through signaling. If the TX UE requests that the RX UE feeds back L1-RSRP multiple times, the TX UE must transmit trigger signaling multiple times.

TX UE may trigger aperiodic L1-RSRP feedback for RX UE through sidelink control information (SCI), for example, SCI transmitted from TX UE to RX UE is aperiodic L1- Contains 1 bit to trigger (request) RSRP feedback. Optionally, the SCI transmitted from the TX UE to the RX UE may always include a 1-bit indication field regardless of whether the power control based on sidelink path loss is configured to be applied. The 1-bit indication field may be used to trigger (request) aperiodic L1-RSRP feedback when configured to apply power control based on sidelink path loss; If power control based on sidelink path loss is not configured to be applied, this 1-bit indication field may be reserved or used to indicate other information. Optionally, the SCI transmitted from the TX UE to the RX UE may include a 1-bit indication field only when it is configured to apply power control based on sidelink path loss; When the power control based on the sidelink path loss is not configured to be applied, the SCI transmitted from the TX UE to the RX UE may not include a 1-bit indication field. That is, in these two cases, the payload of the SCIs is different in size, and the former is one bit larger than the latter.

Optionally, when the TX UE triggers the aperiodic L1-RSRP feedback of the RX UE through SCI, the RX UE measures the RS for RSRP measurement transmitted from the TX UE in the current slot (ie, a slot with trigger signaling). That is, the TX UE must transmit the RS for RSRP measurement in the slot in which the L1-RSRP feedback is triggered. When the RS for L1-RSRP feedback is SL CSI-RS (for convenience of explanation, the SL CSI-RS is hereinafter referred to as simply CSI-RS), signaling for triggering aperiodic L1-RSRP feedback in SCI is, It may implicitly indicate whether the CSI-RS is transmitted in the current slot. That is, if the SCI indicates that the L1-RSRP feedback has been triggered, this implicitly indicates that the CSI-RS is transmitted in the current slot. Alternatively, signaling indicating whether the CSI-RS is transmitted in the current slot of SCI may implicitly trigger aperiodic L1-RSRP feedback. That is, if the SCI indicates that the CSI-RS is transmitted in the current slot, this indicates that it implicitly triggers the L1-RSRP feedback.

Optionally, when the TX UE triggers the aperiodic L1-RSRP feedback of the RX UE through SCI, the TX UE performs an RS for RSRP measurement in the current slot (the slot in which the SCI triggering the aperiodic L1-RSRP is located). May not be transmitted. When the TX UE does not transmit the RS for RSRP measurement in the slot for triggering the aperiodic RSRP feedback, the RX UE feeds back L1-RSRP measured in the nearest RS before the slot with trigger signaling to the TX UE, or Or, the RX UE measures L1-RSRP in the nearest RS after the slot with trigger signaling and feeds it back to the TX UE.

Irregular L1-RSRP feedback

If the sidelink system wants to support periodic L1-RSRP feedback, the L1-RSRP should be transmitted along with periodic sidelink resources. When there are a large number of UEs performing periodic L1-RSRP feedback, interference level and congestion level for NR V2X mode 2 based on distributed communication are definitely deteriorated; In the case of NR V2X mode 1 based on centralized communication, sidelink resource scheduling at the base station side is certainly more complicated. A reasonable method may be non-regular L1-RSRP feedback, that is, the feedback timing for L1-RSRP becomes aperiodic. After the TX UE triggers the irregular L1-RSRP feedback for the RX UE through explicit or implicit signaling, the RX UE continues to feed back L1-RSRPs, and the feedback timing of this L1-RSRP is aperiodic.

Optionally, it is not necessary for the RX UE to feed back each measured L1-RSRP to the TX UE for power control based on sidelink path loss, but feed back at least one L1-RSRP in a predefined or preconfigured gap. Needs to be. RX UE autonomously determines which L1-RSRP is to be fed back in that gap, but the gap between measurement slots corresponding to two adjacent L1-RSRPs at the time of being fed back does not exceed a predefined/preconfigured threshold. It should be ensured to avoid, and accordingly ensure timely L1-RSRP feedback. Optionally, the RX UE feeds back each measured L1-RSRP to the TX UE for power control based on sidelink path loss, that is, the RX UE receives the RS for RSRP measurement transmitted by the TX UE. As long as, L1-RSRP can be measured and fed back.

The TX UE may trigger the irregular L1-RSRP feedback of the RX UE through explicit signaling. For example, the TX UE triggers (configures) irregular L1-RSRP feedback to the RX UE through sidelink RRC signaling, or the MAC UE triggers (configures) irregular L1-RSRP feedback through MAC CE signaling. ; The RX UE receives the trigger (configuration) signaling for the irregular L1-RSRP feedback until it receives the corresponding sidelink RRC signaling or the corresponding MAC CE signaling for terminating the irregular L1-RSRP feedback. Enemy L1-RSRP feedback should be performed.

The TX UE may also trigger the non-canonical L1-RSRP feedback of the RX UE through implicit signaling. For example, in the case of power control based on sidelink path loss, the RX UE is, until the sidelink RRC connection between the TX UE and the RX UE is released, the sidelink RRC connection between the TX UE and the RX UE is established. After that, irregular L1-RSRP feedback can be performed.

Optionally, the system may support periodic/semi-static L1-RSRP feedback, aperiodic L1-RSRP feedback, and/or non-regular L1-RSRP feedback, and trigger each of them to the RX UE through specific signaling. Optionally, the system supports only one of periodic/semi-static L1-RSRP feedback or irregular L1-RSRP feedback, and no specific signal is required for triggering. When the resource pool in which the unicast PSCCH/PSSCH transmitted by the TX UE to the RX UE is located is configured to apply power control based on sidelink path loss, the RX UE is a sidelink RRC connection between the TX UE and the RX UE. Until is released, as long as the sidelink RRC connection between the TX UE and the RX UE is established, periodic/semi-static L1-RSRP feedback or non-regular L1-RSRP feedback may be started by default. As a supplement to periodic/semi-static L1-RSRP feedback or irregular L1-RSRP feedback, the system also supports aperiodic L1-RSRP feedback and can trigger (indicate) this via SCI.

Time delay of L1-RSRP feedback

After measuring the L1-RSRP, the RX UE should feed back the L1-RSRP to the TX UE as quickly as possible. Optionally, the system specifies that the RX UE should feed back the L1-RSRP to the TX UE in a slot after a predefined or preconfigured gap to prepare for transmission of the L1-RSRP. For example, the RX UE must feed back L1-RSRP in the 4th slot after L1-RSRP measurement. If for some reason the RX UE does not have time to feed back L1-RSRP in this slot, this L1-RSRP should be discarded.

Optionally, the system specifies that the RX UE feeds back L1-RSRP to the TX UE within a time window of a predefined or preconfigured length after L1-RSRP measurement, and the time window is the first slot after L1-RSRP measurement. Starting at, or starting at the first slot after a predefined or preconfigured gap from the L1-RSRP measurement, this predefined or preconfigured gap is for preparing for transmission of the L1-RSRP. For example, the RX UE feeds back L1-RSRP in the 4th to 10th slots after L1-RSRP measurement, and the slot used to feed back L1-RSRP specifically depends on the RX UE. In other words, the system designates the fastest timing for L1-RSRP feedback, i.e. the first slot after a predefined or preconfigured gap from the L1-RSRP measurement, for example the 4th slot after the L1-RSRP measurement; The system further designates the last timing for the L1-RSRP feedback, that is, the end time of the time window, for example, the 10th slot after the L1-RSRP measurement. If for some reason the RX UE does not have time to feed back L1-RSRP in this slot, this L1-RSRP should be discarded.

As described above, for each L1-RSRP fed back by the RX UE, the TX UE should be able to determine the slot location in which the corresponding RS for L1-RSRP measurement is located. When the system specifies that the RX UE feeds back L1-RSRP in a slot after a predefined or preconfigured gap from the L1-RSRP measurement, the RX UE can entirely determine the slot position of the corresponding RS. When the system specifies to feed back L1-RSRP to the TX UE within a time window having a predefined or preconfigured length after L1-RSRP measurement, the TX UE is a corresponding RS for L1-RSRP measurement according to a predefined rule. The slot position where is located can be determined, for example, the TX UE considers the received L1-RSRP to be measured based on the nearest RS, which is a predefined or preconfigured gap before the feedback timing. Alternatively, the RX UE indicates the slot position of the RS corresponding to the L1-RSRP fed back through explicit signaling, for example, the RX UE feedbacks the slot position of the corresponding RS when feeding back the L1-RSRP. do.

Feedback method of L1-RSRP

In the existing NR Uu interface, L1-RSRP feedback is supported for beam management, whereas the purpose of SL L1-RSRP feedback in the NR V2X system is power control based on sidelink path loss. Although their purposes are different, the same or similar quantization methods can be used. For example, SL L1-RSRP in the [-140, -44] dBm range is quantized to 7 bits with a quantization gap of 1 dBm. When the RX UE feeds back a plurality of L1-RSRPs corresponding to different measurement slots to the TX UE once, the L1-RSRP measured in the nearest or farthest slot from the timing of the L1-RSRP feedback is considered as the reference L1-RSRP. In the case of L1-RSRPs measured in different slots, differential quantized values compared to the reference L1-RSRP are fed back. Since differences between the L1-RSRPs measured in different slots and the reference L1-RSRP are quantized to 4 bits with a quantization gap of 2 dBm, total information bits are saved and signaling overhead is reduced. For example, it is assumed that the UE feeds back L1-RSRP of 4 slots once, and the total number of feedback bits is 7+(4-1)*4=19. The quantized values or differential quantized values of the plurality of L1-RSRPs fed back once may be sequentially arranged in the order of corresponding measurement timings. For example, a high-order bit is L1-RSRP measured in a slot furthest from the feedback timing, and a low-order bit is L1-RSRP measured in a slot closest to the feedback timing; Alternatively, the upper bit is L1-RSRP measured in the slot closest to the feedback timing and the lower bit is L1-RSRP measured in the slot furthest from the feedback timing. Optionally, considering that the precision of L1-RSRP feedback for power control based on sidelink path loss may be lower than that of L1-RSRP feedback for beam management, where SL L1-RSRP adopts a larger quantization gap. You may. For example, SL L1-RSRP in the [-140, -44] dBm range is quantized as 6 bits with a quantization gap of 2 dBm.

Optionally, the quantized value of L1-RSRP is transmitted through the PSFCH, that is, the RX UE feeds back the L1-RSRP to the TX UE through the PSFCH. In the current 3GPP Rel-16 NR V2X WID, it has been agreed that HARQ-ACK is transmitted through a dedicated PSFCH, and the design for PSFCH can refer to the PUCCH in the NR Uu system, so the transmission of L1-RSRP through the PSFCH is It is possible. For example, after the TX UE triggers the aperiodic L1-RSRP feedback to the RX UE through SCI, PSFCH resources for feeding back L1-RSRP are explicitly indicated in the corresponding SCI, or L1-RSRP Corresponding PSFCH resources for feedback are implicitly determined according to the PSCCH/PSSCH resource location in which the SCI is located. Alternatively, the corresponding PSFCH resources are determined by combining the two methods described above.

When the RX UE has both L1-RSRP feedback and HARQ-ACK feedback in the same slot, and L1-RSRP feedback and HARQ-ACK feedback are for the same UE, L1-RSRP feedback and HARQ-ACK feedback are multiplexed with each other It can be transmitted through the PSFCH. When the total number of bits of the multiplexed L1-RSRP and HARQ-ACK exceeds the maximum number of bits that can be handled by the PSFCH, the HARQ-ACK is fed back preferentially while the L1-RSRP feedback is discarded. Alternatively, the RX UE always preferentially feeds back HARQ-ACK and the L1-RSRP feedback is discarded. Optionally, the PSFCH carrying L1-RSRP and the PSFCH carrying HARQ-ACK are transmitted in different channel formats, and when the L1-RSRP feedback collides with the HARQ-ACK feedback, the HARQ-ACK carries the L1-RSRP. It can be multiplexed in PSFCH format. Optionally, PSFCH carrying L1-RSRP and PSFCH carrying HARQ-ACK are transmitted in the same channel format, and when L1-RSRP feedback collides with HARQ-ACK feedback, PSFCH resources and HARQ for L1-RSRP feedback -If the PSFCH resources for ACK feedback are different resources, L1-RSRP and HARQ-ACK are multiplexed together and transmitted together with the PSFCH resource corresponding to the L1-RSRP feedback; Alternatively, L1-RSRP and HARQ-ACK are multiplexed together and transmitted together with PSFCH resources corresponding to HARQ-ACK. Here, HARQ-ACK may be replaced by CSI, that is, the above-described scheme may be similarly applied to combined transmission of L1-RSRP and CSI.

If the RX UE has both L1-RSRP feedback and data transmission in the same slot, and the L1-RSRP feedback and PSCCH/PSSCH transmission are for the same UE, the L1-RSRP will be transmitted in a piggyback manner of the PSSCH. I can. That is, the L1-RSRP is transmitted with some of the PSSCH resources, and the modulated and encoded symbols of the L1-RSRP are according to a predefined scheme (e.g., the lowest sub of the frequency domain in the first OFDM symbol of the PSSCH resources). From the RE of the carrier location, it is mapped to some of the resource elements (RE) of the PSSCH resource in a time domain priority and frequency domain suboptimal manner.

RX UE has both L1-RSRP feedback and data transmission in the same slot, L1-RSRP feedback and PSCCH / PSSCH transmission is for the same UE, PSCCH 1 PSCCH and 2 PSCCH each carrying different control information When including-Here, the first PSCCH is for indicating basic control information, for example, a target receiving UE ID or a target receiving UE group ID, and some basic information for channel monitoring, and the second PSSCH is the details of the PSSCH. Scheduling information, for example, to indicate the HARQ process number, coding and modulation scheme, and new data indication -, L1-RSRP feedback can be carried in the second PSCCH, the first PSCCH, the second PSCCH is L1 -It may indicate whether to include RSRP feedback.

Similar to representing quantized values of L1-RSRP of multiple slots by MAC CE described below, PSFCH may also represent quantized values of L1-RSRP measured in multiple slots at once. The PSFCH may indicate the quantized value and slot position of the L1-RSRP corresponding to the measurement, similar to indicating the L1-RSRP measurement value and the slot position corresponding to the measurement by the MAC CE described below.

Optionally, the quantized value of L1-RSRP is transmitted by the MAC CE, that is, the RX UE feeds back the L1-RSRP to the TX UE by the PSSCH. Here, the RX UE may multiplex the MAC CE indicating the quantized value of L1-RSRP with data for transmission to other control signaling and/or TX UE, and only MAC CE indicating the quantized value of L1-RSRP The included PSSCH may be transmitted. There is no difference between a method of acquiring PSSCH resources including L1-RSRP feedback and a method of acquiring PSSCH resources for other control signaling/data transmission. The system needs to define a dedicated MAC CE to represent the quantized value of L1-RSRP, for example, the MAC CE contains 1 byte (8 bits), where the first bit R is an inverted bit. The remaining 7 bits represent the quantized value of L1-RSRP. 2 shows the structure of the MAC CE for indicating the L1-RSRP.

3A to 3C are diagrams of a MAC CE structure representing quantized values of L1-RSRPs of a plurality of slots according to an embodiment of the present disclosure.

To further reduce the signaling overhead for feeding back L1-RSRP, the RX UE can feed back quantized values of L1-RSRPs measured in multiple slots at once. For example, as shown in Fig. 3A, the system defines a new MAC CE of 3 bytes (24 bits) to indicate the quantized value of L1-RSRPs in 4 slots. As shown in the figure, the first bit of the MAC CE is an inverted bit, and the subsequent 19 bits are L1-RSRP including a 7-bit L1-RSRP reference quantized value and three 4-bit L1-RSRP differential quantized values. And the remaining 4 bits (proposed to represent characters other than R) are inverted bits. In order to allow the TX UE to determine the slot positions of the corresponding RSs where the fed back L1-RSRPs are measured, these four L1-RSRPs are consecutively measured four before a predefined/preconfigured gap for the feedback timing. It can be designated to the nearest L1-RSRP.

Optionally, the TX UE and the RX UE may differently understand the measurement slot positions corresponding to the L1-RSRP feedback for power control based on sidelink path loss, for example, for some reason, the RX UE is transmitted by the TX UE. RS for RSRP measurement is missed. That is, the RX UE may not have a corresponding L1-RSRP measurement for each RS for RSRP measurement transmitted by the TX UE. To avoid different understanding between the TX UE and RX UE of the measurement slot positions corresponding to the L1-RSRP feedback, the RX UE indicates the measurement slot position corresponding to the L1-RSRP when feeding back L1-RSRP. For example, as shown in Figure 3b, MAC CE represents one L1-RSRP quantized value and the corresponding slot position of the measurement, as shown in Figure 3c, MAC CE is a number of L1-RSRP Represents a number of quantized values and corresponding slot positions for each of the measurements.

The RX UE may take the feedback slot of L1-RSRP as a reference slot and indicate the relative positions of the slots corresponding to the L1-RSRP measurement. For example, the relative position of the slot corresponding to the L1-RSRP measurement is indicated by indicating the absolute gap or the relative gap before the feedback slot of L1-RSRP, and the unit of this indication is the slot , And the absolute gap refers to all a plurality of slots included in the actual gap including slots not configured for V2X transmission, and the relative gap refers to a plurality of slots configured for V2X transmission included in the actual gap. . Optionally, the relative position of the slot corresponding to the L1-RSRP measurement can be determined by adding a predefined gap for preparing the L1-RSRP transmission with respect to the gap indicated by the MAC CE, that is, the reference slot is the L1-RSRP. This is the first slot of the predefined gap before the feedback slot.

Optionally, when the RX UE feeds back L1-RSRP to the TX UE by MAC CE, the L1-RSRP feedback may be triggered by the RX UE according to some rules or events. The system has a time greater than a predefined or pre-configured gap between two L1-RSRP feedbacks transmitted by the RX UE to the same TX UE (this gap is referred to as the L1-RSRP feedback prohibition gap), and the RX UE After the L1-RSRP is fed back once, it designates that the L1-RSRP cannot be fed back to the same TX UE again within this prohibition gap. That is, the RX UE starts a timer with the length of the L1-RSRP feedback prohibition gap after each L1-RSRP feedback, and if the L1-RSRP feedback prohibition gap timer is still running, the RX UE provides L1-RSRP feedback to the same TX UE. Cannot be triggered. The system may also specify that the L1-RSRP feedback is triggered only when the amount of change in the newly measured L1-RSRP exceeds a predefined or preconfigured threshold compared to the previously fed back L1-RSRP. For example, when the L1-RSRP feedback prohibition gap timer expires and the amount of change of the new L1-RSRP exceeds the threshold value compared to the previously fed back L1-RSRP, the RX UE should trigger the L1-RSRP feedback. The system can additionally define a periodic L1-RSRP feedback gap, and the RX UE should start the timer with the length of the periodic L1-RSRP feedback gap after the first feedback of L1-RSRP, and the RX UE should start the periodic L1-RSRP feedback. When the timer expires, the L1-RSRP feedback should be triggered, and when the periodic L1-RSRP feedback timer expires, the periodic L1-RSRP feedback timer should be restarted after triggering the L1-RSRP feedback.

Optionally, in order to solve the problem of resource use low efficiency caused by transmitting the PSSCH including only the L1-RSRP MAC CE, the system can define a waiting window for L1-RSRP feedback, and the RX UE has the PSSCH in that window. It waits until it is transmitted to the TX UE, and if there is a PSSCH to be transmitted to the TX UE in the waiting window, additionally transmits L1-RSRP by PSSCH including L1-RSRP MAC CE or by PSSCH piggyback; And/or, the RX UE waits until the PSSCH is transmitted to the TX UE in this window, and when there is a PSFCH for carrying the HARQ-ACK to be transmitted to the TX UE in the window, L1-RSRP indication information is additionally included. L1-RSRP is transmitted by the PSFCH, that is, L1-RSRP and HARQ-ACK are multiplexed together to be transmitted by the PSFCH. If the RX UE does not have a regular PSSCH to be transmitted to the TX UE within the waiting window and/or the RX UE does not have a PSFCH for carrying the HARQ-ACK to be transmitted to the TX UE within the waiting window, the RX UE has a waiting time. After and before the maximum feedback time delay of the L1-RSRP, the L1-RSRP may be transmitted by the PSSCH including only the L1-RSRP MAC CE.

Embodiment 2: The RX UE feeds back L3-RSRP to the TX UE, and the transmission power of the RS for RSRP measurement does not change, or the TX UE signals information on the transmission power of the RS for RSRP measurement.

In Embodiment 2, the RSRP fed back to the TX UE by the RX UE is L3-RSRP, that is, the RX UE is an performer for performing higher layer filtering to generate L3-RSRP. The RX UE measures RSRP based on the RS transmitted by the TX UE, the physical layer reports the measured L1-RSRP to the upper layer, L1-RSRP undergoes upper layer filtering to generate L3-RSRP, and RX The UE feeds back the generated L3-RSRP to the TX UE, and this TX UE calculates the sidelink path loss between the TX UE and the RX UE based on the received L3-RSRP and the transmit power of the RS for RSRP measurement. . In particular, as shown in Fig. 4, Embodiment 2 includes the following steps.

In step S410, the TX UE triggers the feedback of the L3-RSRP by transmitting signaling to the RX UE.

In step S420, the RX UE feeds back L3-RSRP to the TX UE. Here, the RX UE measures L1-RSRP based on the RS transmitted by the TX UE after receiving the trigger signaling for the L3-RSRP feedback, and the physical layer reports the measured L1-RSRP to the upper layer, and in advance L1-RSRPs within the determined time pass through higher layer filtering to generate L3-RSRP, and the RX UE feeds back the generated L3-RSRP to the TX UE.

In step S430, the TX UE calculates a sidelink path loss between the TX UE and the RX UE based on the received L3-RSRP and the transmission power of the RS for RSRP measurement.

In step S440, the TX UE calculates the transmit power based on the sidelink path loss calculated in step S430, and applies the calculated transmit power to the sidelink transmission transmitted to the RX UE, and the sidelink transmission is PSCCH, PSSCH. , PSFCH, CSI-RS and/or PTRS.

In the second embodiment, the performer generating the L3-RSRP through RSRP upper layer filtering is the RX UE, and the transmission power of the RS for RSRP measurement should not be changed; Alternatively, the transmission power of the RS for RSRP measurement may be changed, but the TX UE must notify the RX UE of information about the transmission power of the RS for RSRP measurement. For example, the TX UE signals information about the relative change in the transmission power of the RS to the RX UE for RSRP measurement, and the RX UE transmits the RS for the measured L1-RSRP after receiving this information. By equally compensating for the change in power, the L1-RSRPs for generating L3-RSRP based on it ensure that the transmit powers of all the measured RSs are equally equal. By compensating for the measured L1-RSRPs, the TX UE can adjust the transmission power of the RS for RSRP measurement according to the channel condition, thereby making the L1-RSRP measurement method more flexible.

Optionally, in step S420, when the RX UE is within the coverage (IC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the RX UE is a UE-specific RRC by the serving base station of the cell where the RX UE is located. Pre-configured through signaling; When the TX UE is out of coverage (OOC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the RX UE is pre-configured through sidelink upper layer parameters in a hard coding scheme.

Optionally, in step S420, the coefficient α of the RSRP higher layer filter used by the RX UE is pre-configured through sidelink RRC signaling by the TX UE, and the TX UE is a corresponding serving base station pre-configuration or hard coding pre-configuration scheme. To obtain this coefficient. That is, the TX UE acquires the coefficients of the RSRP upper layer filter used by the RX UE in step S420 in a manner of preconfiguring a corresponding serving base station or preconfiguring a hard-coded sidelink higher layer parameter, and then performs sidelink RRC signaling. The coefficient α of the upper layer of the RSRP obtained through is signaled to the RX UE.

In Embodiment 2, step S410 may be omitted, that is, the TX UE does not need to trigger the L3-RSRP feedback of the RX UE through explicit signaling. For example, when the power control based on the sidelink path loss is configured to be applied, the RX UE starts step S410 as soon as the sidelink RRC connection between the TX UE and the RX UE starts to be established, and is transmitted by the TX UE. Based on the RS, the RSRP is continuously measured and L3-RSRP is continuously generated and fed back until the sidelink RRC connection between the TX UE and the RX UE is released. In this way, signaling overhead to trigger L3-RSRP feedback can be avoided.

TX UE signals information on transmission power of RS for RSRP measurement to RX UE

Like PSSCH, RS for RSRP measurement is applied to power control-based downlink path loss and/or sidelink path loss in order to efficiently use transmission power, thereby reducing the transmission power as much as possible based on transmission reliability satisfaction. Accordingly, it is possible to achieve the purpose of power saving and avoid serious interference to the base station of the serving cell and/or the sidelink system. When the transmission power of the RS dynamically changes according to the change in the downlink path loss and/or the sidelink path loss, the TX UE must inform the RX UE of information about the transmission power of the RS for RSRP measurement.

Here, since the sidelink path loss between the TX UE and the RX UE is calculated by the TX UE, the TX UE does not signal absolute information about the transmission power of the RS for RSRP measurement to the RX UE, and the RS for RSRP measurement It is possible to notify the RX UE only of information about the change in the transmission power of, and accordingly, the transmission powers of all the RSs in which L1-RSRPs for generating L3-RSRPs are measured are equally equal at the RX UE side. Can be guaranteed.

Optionally, the TX UE displays relative change information for the transmission power of the RS for RSRP measurement currently transmitted through SCI (ie, transmitted with SCI). When the RS for RSRP measurement is the DRMS of PSCCH/PSSCH, the SCI may include a field indicating relative change information of the transmission power of the currently transmitted DMRS. When the RS for RSRP measurement is SL CSI-RS, SCI includes a field indicating relative change information for the transmission power of the currently transmitted CSI-RS, and this is interpreted only when CSI-RS indicates transmission of CSI-RS. In other words, the CSI-RS may or may not be present in PSCCH/PSSCH transmission.

In one example, the above-mentioned relative change information for the transmission power of the RS indicated by the SCI is the amount of change compared to the reference transmission power. The reference transmit power is determined by the TX UE itself. The TX UE does not need to inform the RX UE of a specific value of the reference transmit power. RX UE to ensure that the transmission powers of all the RSs measured L1-RSRPs for generating L3-RSRP based on it are equally equal, that is, to ensure that the same as using the reference transmission power, The change in the transmission power of the RS compared with the received reference transmission power must be compensated for the corresponding L1-RSRP. After receiving the L3-RSRP, the TX UE should calculate the difference between the L3-RSRP and the reference transmit power as the sidelink path loss between the TX UE and the RX UE. When the reference transmission power of the RS determined by the TX UE is changed, the TX UE must notify the RX UE to restart RSRP upper layer filtering through sidelink RRC signaling. After receiving the signaling to restart the upper layer filtering, the RX UE must restart the RSRP upper layer filtering, that is, the L1-RSRPs measured before and after receiving the signaling are used for the same upper layer filtering for the L3-RSRP. Can't.

In another example, the above-mentioned relative change information for the transmit power of the RS indicated by the SCI is the amount of change compared with the transmit power of the last transmitted RS. Here, the TX UE itself determines the initial transmission power of the RS, and there is no need to notify the RX UE of a specific value of the initial transmission power. The RX UE regards the transmit power of the received first RS transmitted by the TX UE as the initial transmit power. The RX UE calculates the amount of change in the transmission power of each transmitted RS by comparing it with the initial transmission power by successive accumulation, and compensates it for the measured L1-RSRP, thereby generating L3-RSRP based on the L1 -Ensure that the transmit powers of all RSs for which the RSRPs are measured are equally equal at the RX UE side, that is, equal to that of using the initial transmit power. After receiving the L3-RSRP, the TX UE must calculate the difference between the L3-RSRP and the initial transmit power as the sidelink path loss between the TX UE and the RX UE. When the initial transmit power of the RS determined by the TX UE is changed, the TX UE must notify the RX UE to restart RSRP upper layer filtering through sidelink RRC signaling. After receiving the signaling for restarting RSRP upper layer filtering, the RX UE must restart RSRP upper layer filtering, that is, the L1-RSRPs measured before and after receiving the signaling are subjected to the same upper layer filtering for L3-RSRP. Should not be used. In addition, the RX UE restarts the cumulative calculation of the change amount of the transmission power of the RS compared with the initial transmission power, and after restarting the RSRP upper layer filtering, the first received RS transmitted by the TX UE should be taken as the initial transmission power. do. When the SCI indicating the relative change information of the RS transmission power is lost, there is an error in the change amount of the RS transmission power calculated by the RX UE in an accumulative manner compared to the initial transmission power, and this error continues to accumulate. To avoid continuous error accumulation and expansion, the TX UE must reset the initial transmit power of the RS within a predefined or pre-configured gap. That is, the system must notify the RX UE to restart the RSRP upper layer filtering within the predefined or pre-configured gap, and the RX UE receives the signaling to restart RSRP upper layer filtering and then the RSRP upper layer It specifies that filtering should be restarted and the cumulative calculation of the change in RS transmission power should be restarted.

In another example, the above-mentioned relative change information on the transmission power of the RS indicated by the SCI may be a change amount compared with the transmission power of the last transmitted RS or a change amount compared with the reference transmission power. The interpretation method for the relative change information indicated by the SCI configured through sidelink RRC signaling by the TX UE is one of the above two methods, or the TX UE uses a 1-bit SCI field indicating the relative change information, It further indicates that the interpretation method of the change information is one of the above two methods, that is, the TX UE may dynamically switch between the two methods.

Optionally, the TX UE displays relative change information of the transmission power of the RS for RSRP measurement through MAC CE or sidelink RRC signaling. The above description of the relative change information of the transmission power of the RS indicated by SCI may be applied here in the same manner.

For example, the TX UE represents the amount of change in the transmission power of the RS compared to the reference transmission power through MAC CE or sidelink RRC signaling, and the RX UE is the transmission power of the received RS for the measured L1-RSRP. Compensates for the relative amount of change. When the reference transmit power of the RS is changed, the TX UE must notify the RX UE to restart the upper layer filtering of the RSRP.

Alternatively, the TX UE indicates the amount of change in the transmit power of the RS compared to the transmit power of the last transmitted RS through MAC CE or sidelink RRC signaling. The RX UE calculates the amount of change in the transmission power of the transmitted RS whenever compared with the initial transmission power through continuous accumulation. The initial transmit power corresponds to the first RS for RSRP measurement transmitted by the TX UE and received by the RX UE. The RX UE compensates the measured L1-RSRP for the relative change amount of the calculated RS transmission power. When the initial transmit power of the RS is changed, the TX UE must notify the RX UE to restart the upper layer filtering of RSRP and the cumulative calculation of the change amount of the transmit power of the RS compared with the initial transmit power, and this initial transmit power Corresponds to the first RS for RSRP measurement that is transmitted from the TX UE and received by the RX UE after RSRP upper layer filtering is reset. In order to avoid continuous error expansion in the cumulative calculation, the system allows the TX UE to restart the RSRP upper layer filtering and restart the cumulative calculation of the relative change amount of the transmit power of the RS within a predefined or pre-configured time gap. It is specified to signal to.

TX UE indicates relative change information of transmission powers of RSs for multiple transmissions at once through MAC CE or sidelink RRC signaling, unlike information on relative change of transmission power of RS for RSRP measurement through SCI. And, as a result, overall signaling overhead is saved. For example, the relative change information of the transmission power of RSs including the currently transmitted RS and the N previously transmitted Rs is indicated by MAC CE or sidelink RRC signaling, where N is a predefined or preconfigured Value. In order for the TX UE and RX UE to have a completely identical understanding of the slot position of the RS with the corresponding power change information, MAC CE or sidelink RRC signaling is added to the relative change information of the transmission power of the RS, and the corresponding slot of the RS. The location can be further indicated.

In addition, when the change amount of the transmission power of the RS compared to the reference transmission power is 0, or the change amount of the transmission power of the RS compared to the transmission power of the last transmitted RS is 0, the TX UE changes the relative transmission power of the RS. It may not transmit the corresponding MAC CE or sidelink RRC signaling indicating information. Therefore, when the RX UE does not receive the relative change information of the transmission power of a specific RS, the change amount of the transmission power of the RS compared to the reference transmission power is 0, or the change amount of the transmission power of the last transmitted RS is 0. Can be regarded as Conversely, when the relative change information of the transmission power of the RS is indicated by SCI, regardless of whether the transmission power of the RS is changed, the corresponding SCI indication field is provided so that the payload size of the SCI is known to the RX UE. It must be included, and accordingly, the payload size of the SCI must be kept constant. That is, even if the relative change amount of the transmission power of the RS is 0, the SCI must also include a corresponding indication field. From this point of view, indicating the relative change information of the transmission power of the RS through MAC CE or sidelink RRC signaling can save the overall overhead of signaling compared to the indication by SCI. This is because the transmit powers of the PSSCH and the RS transmitted with it are changed only when the downlink path loss and/or the sidelink path loss calculated by the TX UE are changed. The total number by which the transmission power of the RS is changed should be less than the total number of which the transmission power of the RS is not changed. Therefore, it is more economical and effective to indicate the relative change information of the transmission power of the RS through MAC CE or RRC signaling.

Design for CSI-RS with unchanged transmit power

Optionally, the system requires that the transmission power of the RS for RSRP measurement is not changed, that is, the TX UE does not need to notify the RX UE of the information about the transmission power of the RS for RSRP measurement, which is signaling over. There is an advantage of saving head. In order to keep the transmit power unchanged, the RS for RSRP measurement uses preconfigured transmit power, and power control based on downlink path loss or power control based on sidelink path loss cannot be applied. none.

CSI-RS is used for RSRP measurement, and in order to avoid resource fragmentation caused by CSI-RS transmission, the system specifies that CSI-RS cannot be transmitted alone, that is, CSI-RS is used with PSCCH/PSSCH. It should be transmitted, that is, it is assumed that the CSI-RS specifies that it is mapped to some REs on specific PSCCH and/or PSSCH symbols. In addition, the system designates that the total transmission power of each PSCCH/PSSCH symbol in a slot should be kept the same in order to avoid an effect on the decoding performance of the PSCCH/PSSCH due to a sudden power change. Since CSI-RS is mapped to some OFDM symbols and not to other OFDM symbols, the total transmit power of each PSCCH/PSSCH symbol in the slot is guaranteed to be the same, without changing the transmit power of the CSI-RS. It is difficult to maintain, and a new design is required for the mapping pattern of SL CSI-RS.

Optionally, the CSI-RS for RSRP measurement occupies the same number of REs in each OFDM symbol of the PSCCH/PSSCH, and the REs for the CSI-RS on each OFDM symbol are at the same position or have a specific interval by interleaving. It can be distributed. Since the number of REs for CSI-RS on each OFDM symbol is the same, PSCCH/PSSCH uses power control based on downlink path loss and/or power control based on sidelink path loss, and CSI in the same slot -When the RSs use the pre-configured transmission power, the total transmission power of each OFDM symbol (i.e., the sum of the transmission power of PSCCH/PSSCH and the transmission power of CSI-RS) can be kept the same, and thereby It is possible to avoid the effect on the decoding performance of the PSCCH/PSSCH due to power change.

5A shows a pattern design for CSI-RS. In FIG. 5A, the first OFDM symbol of the slot is for automatic gain control (AGC), that is, the UE transmits a signal with the same power as data transmission in the same slot through this symbol, but a specific transmission signal is It depends on the implementation of the UE. The last OFDM symbol of the slot is GP (Guard Period), i.e. the UE does not transmit anything on this symbol. The 2nd to 4th symbols of the slot are for PSCCH transmission. The 5th to 13th symbols of the slot are for PSSCH transmission. One RE for CSI-RS transmission exists in each PRB of each PSCCH/PSSCH symbol, and the frequency domain position of the CSI-RS RE of each OFDM symbol is the same.

5B shows another pattern design for CSI-RS. Similar to FIG. 5A, in FIG. 5B, there is one RE for CSI-RS transmission in each PRB of each PSCCH/PSSCH symbol. The difference is that in FIG. 5B, the frequency domain position of the CSI-RS RE of each OFDM symbol may be different, and hopping may be performed at a specific interval in the frequency domain.

Optionally, the CSI-RS for RSRP measurement completely occupies the last one or two available OFDM symbols in time in the slot of the PSCCH/PSSCH, and the OFDM symbol(s) occupied by the CSI-RS has PSCCH/ There is no RE for PSSCH transmission. The CSI-RS may occupy all REs within the allocated bandwidth of the OFDM symbol(s), or may occupy some of the REs within the allocated bandwidth of the OFDM symbol. Like SRS transmission in existing systems, this design ensures that the total transmission power of each PSCCH/PSSCH symbol is the same, while maintaining the transmission power of the CSI-RS unchanged. When the PSCCH/PSSCH uses power control based on downlink path loss and/or sidelink path loss, and CSI-RSs in the same slot use preconfigured transmission power, a sudden power change occurs between PSCCH/PSSCH transmission and CSI. It occurs only between -RS transmissions, and the CSI-RS has little effect on the detection of the CSI-RS because it is based on the detection of the sequence.

5C shows another pattern design for CSI-RS. In Figure 5c, the first OFDM symbol of the slot is for automatic gain control (AGC), that is, the UE transmits a signal with the same power as data transmission in the same slot through this symbol, but a specific transmission signal is Depends. The last OFDM symbol of the slot is GP (Guard Period), i.e. the UE does not transmit anything on this symbol. The 2nd to 4th symbols of the slot are for PSCCH transmission. The 5th to 12th symbols of the slot are for PSSCH transmission. The 13th symbol of the slot is for CSI-RS transmission, and all REs within the same transmission bandwidth as the PSSCH in the symbol are occupied by the CSI-RS.

DMRS can be used for RSRP measurements under certain conditions (transmit power remains unchanged)

In general, the DMRS should use the same EPRE as the associated physical channel. When PSCCH/PSSCH is configured to apply power control based on downlink path loss and/or sidelink path loss, the transmission power of DMRS of PSCCH/PSSCH is also changed in downlink path loss and/or sidelink path loss. It may vary according to, and thus it is difficult to keep the transmission power of the DMRS unchanged. As described above, if the transmission power of the RS for RSRP measurement can be kept unchanged, the TX UE does not need to notify the RX UE of the transmission power of the RS for RSRP measurement, as a result It is possible to save signaling overhead. Due to the specificity of DMRS, only DMRS under certain conditions can be used for RSRP measurement.

Optionally, the data of the PSCCH/PSSCH and the DMRS use different transmit powers, and the former (data of the PSCCH/PSSCH) is applied to power control based on downlink path loss and/or sidelink path loss, but the latter (DMRS of PSCCH/PSSCH) uses a pre-configured transmit power and keeps the transmit power semi-statically unchanged. In order to maintain the total transmission power of each PSCCH/PSSCH symbol in the slot to be the same and to keep the transmission power of the DMRS unchanged, a design similar to the CSI-RS described above may be applied to the DMRS, that is, the DMRS is Each PSCCH/PSSCH symbol occupies the same number of REs. In addition, since the transmission power of the DMPS and the transmission power of the data are different, when a modulation method of QPSK or higher is used, the RX UE needs to know the power difference between the DMRS and the data to accurately demodulate the data. For example, when the DMRS is configured for RSRP measurement for power control based on sidelink path loss, the power difference between the DMRS and data should be indicated in the SCI. Alternatively, in order to avoid signaling overhead for indicating the power difference between the DMRS and the data, the system specifies that the PSCCH/PSSCH transmission does not use a modulation scheme higher than QPSK.

Optionally, the system specifies that power control based on sidelink path loss is applied only to the PSSCH, not the PSCCH. When the TX UE is out of coverage (OOC) of the cellular network, that is, when the PSCCH transmitted by the TX UE is not applied to power control based on downlink path loss, the DMRS of the PSCCH is based on sidelink path loss. It can be used to measure RSRP for power control.

Optionally, the system specifies that power control based on sidelink path loss is not applied to the broadcast PSCCH/PSSCH. When the TX UE is the OOC of the cellular network, that is, when power control based on downlink path loss is not applied to the broadcast PSCCH/PSSCH transmitted by the TX UE, the groupcast or unicast transmitted by the TX UE When PSCCH/PSSCH is configured to apply power control based on sidelink path loss, DMRS of broadcast PSCCH/PSSCH transmitted by TX UE is groupcast or unicast RSRP for power control based on sidelink path loss Can be used for measurement.

Optionally, when the TX UE is OOC, that is, when the groupcast PSCCH/PSSCH transmitted by the TX UE does not use power control based on downlink path loss, the unicast PSCCH/PSSCH transmitted by the TX UE is When configured with power control based on sidelink path loss, the DMRS of the groupcast PSCCH/PSSCH transmitted by the TX UE may be used for unicast RSRP measurement for power control based on sidelink path loss.

The DMRS under specific conditions can be used independently for RSRP measurement for power control based on sidelink path loss, that is, the system allows the RX UE to perform RSRP measurement based on CSI-RS and/or DMRS under specific conditions. Can be configured to perform; Alternatively, the DMRS under specific conditions cannot be independently used for RSRP measurement for power control based on sidelink path loss, and can be used only to assist CSI-RS.

Optionally, when the TX UE is OOC, that is, when the unicast PSCCH/PSSCH transmitted by the TX UE does not use power control based on downlink path loss, the unicast PSCCH/PSSCH transmitted by the TX UE is When configured with power control based on sidelink path loss, the DMRS of unicast PSCCH/PSSCH transmitted by the TX UE is power control based on sidelink path loss before the RX UE first feeds back L3-RSRP. CSI-RS can be assisted in unicast RSRP measurement for After the RX UE feeds back L3-RSRP and the TX UE adjusts the transmit power of PSCCH/PSSCH, the RX UE should measure L1-RSRP based only on CSI-RS.

Optionally, the system may also simultaneously support Embodiment 1 (L1-RSRP feedback) and Embodiment 2 (L3-RSRP feedback) discussed above, and which method to use can be configured. For example, the system configures power control based on sidelink path loss for one resource pool to use L1-RSRP feedback, and based on sidelink path loss for another resource pool to use L3-RSRP feedback. You can configure the power control. The TX UE may also determine which one to use according to the Channel Busy Ratio (CBR) for the resource pool. The L3-RSRP feedback is used when the CRB is greater than a predefined/preconfigured threshold to save the overall signaling overhead for RSB feedback. The L1-RSRP feedback is used when the CRB is lower than a predefined/preconfigured threshold in order to obtain greater flexibility for adjusting the transmit power of the reference signal.

Example 3: The RX UE calculates the sidelink path loss between the TX UE and the RX UE and feeds it back to the TX UE.

In Embodiment 3, the RX UE calculates the sidelink path loss between the TX UE and the RX UE, and feeds back the calculated sidelink path loss to the TX UE. The RX UE measures RSRP based on the RS transmitted by the TX UE, the physical layer reports the measured L1-RSRP to the upper layer, L1-RSRP undergoes upper layer filtering to generate L3-RSRP, and RX The UE calculates the sidelink path loss between the TX UE and the RX UE based on the generated L3-RSRP and the transmission power of the RS for RSRP measurement signaled by the TX UE, and calculates the calculated sidelink path loss to the TX UE. Feedback to In particular, as shown in Fig. 6, Embodiment 3 includes the following steps.

In step S610, the TX UE transmits signaling for triggering the feedback of the sidelink path loss to the RX UE.

In step S620, the RX UE calculates the sidelink path loss and feeds it back to the TX UE. In particular, after receiving the signaling for triggering the feedback of the sidelink path loss, the RX UE measures the L1-RSRP based on the RS transmitted by the TX UE, and the physical layer transfers the measured L1-RSRP to the upper layer. Reports, L1-RSRPs at a predetermined time undergo higher layer filtering to generate L3-RSRP, and the RX UE is based on the generated L3-RSRP and the transmission power of the RS for RSRP measurement signaled by the TX UE. The sidelink path loss between the TX UE and the RX UE is calculated, and the generated sidelink path loss is fed back to the TX UE.

In step S630, the TX UE calculates transmission power based on the received sidelink path loss, applies the calculated transmission power to the sidelink transmission to the RX UE, and the sidelink transmission is PSCCH, PSSCH, PSFCH, CSI- Includes RS and/or PTRS.

Optionally, in step S620, when the RX UE is within the coverage (IC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the RX UE is served in the cell where the RX UE is located through UE-specific RRC signaling. Pre-configured by the base station; When the RX UE is out of coverage (OOC) of the cellular network, the coefficient α of the RSRP upper layer filter used by the RX UE is pre-configured by the sidelink upper layer parameter in a hard coding scheme.

Optionally, in step S620, the coefficient α of the RSRP upper layer filter used by the RX UE is pre-configured through sidelink RRC signaling by the TX UE, and the TX UE is configured in a preconfigured manner or hard by the corresponding serving base station. This coefficient is obtained in a manner pre-configured with the coding method. That is, the TX UE acquires the coefficients of the RSRP upper layer filter used by the RX UE in step S420 in a manner that is preconfigured by the corresponding serving base station or preconfigured by hard-coded sidelink higher layer parameters, The coefficient α of the RSRP upper layer filter obtained through sidelink RRC signaling is signaled to the RX UE.

In Embodiment 3, step S610 may be omitted, that is, the TX UE does not need to trigger the feedback of the sidelink path loss to the RX UE through explicit signaling. For example, when configured to apply power control based on sidelink path loss, the RX UE may start step S620 as soon as the sidelink RRC connection between the TX UE and the RX UE starts to be established, and also RX UE L1-RSRP is measured based on the RS continuously transmitted by the TX UE, L3-RSRP is continuously generated through upper layer filtering of the RSRP, and the sidelink RRC connection between the TX UE and the RX UE is released. Until, the sidelink path loss between the TX UE and the RX UE is continuously calculated and fed back. In this way, signaling overhead to trigger sidelink path loss feedback can be avoided.

TX UE signals absolute information on transmission power of RS for RSRP measurement to RX UE

In Embodiment 3, in order for the RX UE to calculate the sidelink path loss between the TX UE and the RX UE, the TX UE must notify the RX UE of a specific value of the transmit power of RS for RSRP measurement. For example, the TX UE signals a specific value of transmit power for each transmitted RS for RSRP measurement; Alternatively, the TX UE signals a specific value of the reference transmission power of the RS for RSRP measurement to the RX UE, and signals a change amount of the transmission power of the RS for the RSRP measurement transmitted every time compared with the reference transmission power to the RX UE, or ; Alternatively, the TX UE signals a specific value of the initial transmission power of the RS for RSRP measurement to the RX UE, and then transmits the RS for RSRP measurement that is transmitted every time the transmission power of the RS for the last transmitted RSRP measurement is compared. The amount of power change is signaled to the RX UE.

Here, when the TX UE signals the amount of change in the transmission power of the RS for RSRP measurement transmitted every time compared with the reference transmission power, or when comparing the transmission power of the RS for the last transmitted RSRP measurement, the RSRP measurement transmitted every time For the case of signaling the change amount of the transmission power of the RS for the RX UE, the related methods described in the second embodiment may be reused. In Embodiment 2, the RX UE is an entity for performing RSRP higher layer filtering, and the TX UE transmits relative change information on the transmission power of RS for RSRP measurement to the RX UE without signaling specific values of the transmission powers of RS. It should be notified, and a similar indication method for the relative change information and restart signaling of RSRP upper layer filtering can be reused. In addition, the TX UE must notify the RX UE of the reference transmission power or initial transmission power of the RS for RSRP measurement through sidelink RRC signaling or MAC CE.

RS for RSRP measurement

In the above-described embodiments 1, 2 and 3, the RS for RSRP measurement may be SL CSI-RS and/or DMRS, and the DMRS is a DMRS for PSSCH demodulation and/or a DMRS for PSCCH demodulation.

Optionally, the system configures CSI-RS and/or DMRS for RSRP measurement for power control based on sidelink path loss through dedicated signaling, and, for example, power based on sidelink path loss of the resource pool. The parameters of the control include configuration information on the RS for RSRP measurement. The system can configure only CSI-RS for RSRP measurement for power control based on sidelink path loss, and can configure only DMRS for RSRP measurement for power control based on sidelink path loss. For power control based on link path loss, both CSI-RS and DMRS for RSRP measurement may be configured. When the CSI-RS and DMRS are transmitted in the same slot, the accuracy of RSRP measurement may be improved. When the CSI-RS and DMRS are transmitted in different slots, the number of samples of L1-RSRP may be increased to make the generated L3-RSRP more accurate.

When both CSI-RS and DMRS are used for RSRP for power control based on sidelink path loss, CSI-RS and DMRS use the same transmission power. Alternatively, CSI-RS and DMRS use different transmit powers. Thereafter, a reference RS is defined, the power offset of another RS compared to the reference RS is signaled to the RX UE, and the RX UE calculates the measured RSRP based on the other RS, based on the reference signal RS, and based on the power offset. Convert the measured equivalent RSRP value. For example, DMRS is defined as a reference RS for RSRP measurement, and CSI-RS is defined as a secondary RS for RSRP measurement. The TX UE must semi-statically maintain the difference between the transmission powers of the CSI-RS and the DMRS, and the power offset of the CSI-RS compared to the DMRS through sidelink RRC signaling or MAC CE signaling is the RX UE. Should be notified.

Optionally, the DMRS is always used for RSRP measurement for power control based on sidelink path loss without configuration through dedicated signaling; The CSI-RS may be configured to be used for RSRP measurement for power control based on sidelink path loss. For example, the parameters of power control based on the sidelink path loss of the resource pool include configuration information on whether the CSI-RS is used for RSRP measurement. That is, in the case of the RX UE, the RSRP measurement based on the DMRS is the main one, and the RSRP measurement based on the CSI-RS is supplementary. When the CSI-RS is configured to support RSRP measurement of the DMRS, and the CSI-RS and the DMRS use different transmission powers, the TX UE must notify the RX UE of the power offset of the CSI-RS compared to the DMRS.

Optionally, CSI-RS is always used for RSRP measurement for power control based on sidelink path loss without configuration through dedicated signaling; The DMRS may be configured to be used for RSRP measurement for power control based on sidelink path loss through dedicated signaling. For example, the parameters of power control based on the sidelink path loss of the resource pool include configuration information on whether or not the DMRS is used for RSRP measurement. That is, in the case of the RX UE, RSRP measurement based on CSI-RS is the main thing, and RSRP measurement based on DMRS is supplementary. If the DMRS is configured to support RSRP measurement of CSI-RS, and the CSI-RS and DMRS use different transmit powers, the TX UE must notify the RX UE of the power offset of the DMRS compared to the CSI-RS.

Optionally, the UE cannot transmit the CSI-RS alone in one slot, and the CSI-RS must be transmitted together with the PSCCH/PSSCH. In one example, the CSI-RS may be transmitted with broadcast, multicast or unicast PSCCH/PSSCH. In another example, the CSI-RS is transmitted with a groupcast or unicast PSCCH/PSSCH. In another example, the CSI-RS is transmitted only in unicast PSCCH/PSSCH. When the CSI-RS is transmitted with the broadcast PSCCH/PSSCH, the CSI-RS is for one, plural or all of the receiving UEs of the broadcast PSCCH/PSSCH for measuring RSRP and/or CSI; When the CSI-RS is transmitted with the groupcast PSCCH/PSSCH, the CSI-RS is for one, plural or all of the target receiving UE groups of the groupcast PSCCH/PSSCH for measuring RSRP and/or CSI; When the CSI-RS is transmitted with the unicast PSCCH/PSSCH, the CSI-RS is used only for the target receiving UE of the unicast PSCCH/PSSCH to measure RSRP and/or CSI. The CSI-RS is mapped to some REs of specific OFDM symbols in one slot according to a predefined or preconfigured pattern. For example, the CSI-RS is mapped to only some REs of the PSSCH resource, or the CSI-RS is mapped to the PSCCH resource and some REs of the PSSCH resource. The transmission bandwidth of the CSI-RS should be the same as the transmission bandwidth of the PSSCH. The TX UE indicates whether the CSI-RS is transmitted in the current slot by 1 bit of SCI. When SCI indicates that CSI-RS is transmitted in the current slot, rate matching should be performed for transmission of PSCCH and/or PSSCH based on the number of all UEs except CSI-RS REs, or CSI-RS REs The PSCCH and/or PSSCH signals originally mapped to are discarded.

In the above-described three embodiments, for various reasons, the RX UE may not measure L1-RSRP for a certain period of time and/or may not feed back L1-RSRP, for example, the TX UE is the RX UE during this time. May not transmit the RS for RSRP measurement to the user, or the RX UE may fail to receive the RS for RSRP measurement transmitted by the TX UE during this time, or the RX UE may perform L1-RSRP during this time. If the feedback fails, L1-RSRP measurement and/or L1-RSRP feedback may be interrupted.

Optionally, the interruption time of L1-RSRP measurement and/or L1-RSRP feedback should not exceed a predefined or preconfigured threshold. In particular, the TX UE must transmit the RS for RSRP measurement at least once during this threshold, that is, the gap between the two RSs for RSRP measurement adjacent to the time transmitted by the TX UE is a predefined or preconfigured threshold. Must not exceed the value; And/or, the RX UE must measure L1-RSRP at least once during this threshold, that is, the gap between measurement slots corresponding to two L1-RSRP adjacent to the time measured by the RX UE is predefined Or does not exceed a preconfigured threshold; And/or, the RX UE must feed back at least one L1-RSRP during this threshold, that is, a gap between measurement slots corresponding to two L1-RSRP adjacent to the time fed back by the RX UE is predefined Or does not exceed a preconfigured threshold.

Optionally, there is no limitation on the interruption time of L1-RSRP measurement and/or L1-RSRP feedback. When the interruption time of L1-RSRP measurement and/or L1-RSRP feedback exceeds a predefined or pre-configured threshold, the entity performing upper layer filtering must restart RSRP upper layer filtering.

Example 4: TX UE transmits signaling for triggering SL CSI feedback to RX UE, and RX UE feeds back the measured SL CSI to TX UE.

In Example 4, in order for the TX UE to better adjust the modulation coding scheme (Modulation Coding Scheme, MCS) of the sidelink transmission, the RX UE is measured between the TX UE and the RX UE in order to achieve the effect of link adaptation. The sidelink channel state information (Sidelink Channel-State Information, SL CSI) is fed back to the TX UE. In particular, as shown in Fig. 7, Embodiment 4 includes the following steps.

In step S710, the TX UE transmits signaling for triggering SL CSI feedback to the RX UE. For example, the TX UE transmits signaling for triggering SL CSI feedback to the RX UE through SCI.

In step S720, the RX UE measures SL CSI based on the SL CSI-RS transmitted by the TX UE.

In step S730, the RX UE feeds back the measured SL SCI to the TX UE.

Optionally, the TX UE triggers SL CSI feedback to the RX UE through SCI, that is, SCI contains 1 bit indicating whether SL CSI feedback is triggered, or SCI triggers SL CSI feedback, and It includes a plurality of bits indicating whether to trigger a specific mode among the plurality of SL CSI feedback modes preconfigured by the upper layer. Here, the TX UE configures a plurality of SL CSI feedback modes in the RX UE through SL RRC signaling, for example, subband CSI feedback or wideband CSI feedback. In addition, the TX UE may indicate the transmission of the CSI-RS to the RX UE through SCI, that is, the SCI includes 1 bit indicating whether the CSI-RS is transmitted in the slot of the SCI, or the SCI is CSI- It includes a plurality of bits indicating whether an RS is transmitted and whether a specific CSI-RS is transmitted among a plurality of CSI-RSs preconfigured by an upper layer. Here, the TX UE configures a plurality of CSI-RSs in the RX UE through SL RRC signaling, for example, antenna port configuration and/or pattern configuration of a plurality of CSI-RSs.

In one example, an SCI field indicating whether SL CSI-RS is transmitted and an SCI field indicating whether SL CSI feedback is triggered are two independent indication fields. For example, SL CSI feedback may not be triggered in a slot in which transmission of SL CSI-RS is indicated, a CSI-RS may not be transmitted in a slot indicated as being triggered by SL CSI feedback, and a TX UE may have SL CSI feedback. After this triggering, one or more CSI-RS slots may be transmitted for SL CSI measurement by the RX UE.

In another example, the SCI field indicating whether the SL CSI-RS is transmitted and the SCI field indicating whether the SL CSI feedback is triggered are two different indication fields, and these two indication fields have some association. For example, if the SCI indicates the trigger of SL CSI feedback, the SL CSI-RS must be transmitted, that is, the SCI must also indicate the transmission of the SL CSI-RS, and this transmitted SL CSI-RS must be the SL CSI For measurement; If SCI indicates transmission of SL CSI-RS, SL CSI feedback need not be triggered, that is, SCI may not trigger SL CSI feedback, and this transmitted SL CSI-RS is measured for other purposes. For (eg, L1-RSRP measurement).

In another example, the SCI field indicating whether the SL CSI-RS is transmitted and the SCI field indicating whether the SL CSI feedback is triggered are the same field. For example, if the SCI indicates that the SL CSI feedback is triggered, the SL CSI-RS may be implicitly indicated as being transmitted in this slot, and if the SCI indicates that the SL CSI feedback is not triggered, the SL CSI -RS may be implicitly indicated as not being transmitted in this slot; Alternatively, if SCI indicates transmission of SL CSI-RS in this slot, it may be implicitly indicated as triggering SL CSI feedback, and if SCI indicates that SL CSI-RS is not transmitted in this slot, SL It can be implicitly indicated that CSI feedback is not triggered.

Optionally, after receiving the signaling for triggering SL CSI feedback transmitted by the TX UE, the RX UE feeds back the SL CSI to the TX UE within a time window of a predefined or preconfigured length. That is, the gap between the signaling for triggering the SL CSI feedback transmitted by the TX UE and the corresponding SL CSI fed back by the RX UE is not fixed but variable. Within the time window for SL CSI feedback, a slot for feeding back SL CSI is autonomously determined by the RX UE. If the RX UE fails to feed back SL CSI within the time window for SL CSI feedback, this SL CSI should be discarded. The introduction of a time window for SL CSI feedback is to ensure the timeliness of SL CSI feedback, and expired SL CSI feedback is not only bad for the system, but also has disadvantages.

In one example, the time window for SL CSI feedback is defined as starting from the time the signaling to trigger SL CSI feedback transmitted by the TX UE is received by the RX UE. In another example, the time window for SL CSI feedback is defined as starting from a fixed time after signaling to trigger SL CSI feedback transmitted by the TX UE is received by the RX UE. As shown in FIG. 8, the time window for SL CSI feedback starts from the minimum preparation time for SL CSI feedback after the slot triggering the SL CSI feedback, and the minimum preparation time is a processing time for transmitting SL CSI, etc. Includes. For example, the minimum preparation time for SL CSI feedback is N-1 slot, and the time window for SL CSI feedback starts at the N-th slot after the slot that triggers SL CSI feedback, where N is a predefined value. Is assumed. When the SL CSI is fed back through the PSFCH or the piggyback method of the PSSCH in the physical layer, the minimum preparation time as the CSI feedback of the Uu system may be used (ie, N=4), and the SL CSI is fed back through the MAC CE. , The minimum preparation time for SL CSI feedback may be larger than that for CSI feedback of the Uu system (eg, N=5).

In one example, the time window for SL CSI feedback is defined as starting from the time when the RX UE receives the CSI-RS transmitted by the TX UE. In another example, the time window for SL CSI feedback is defined as starting from a fixed time after the RX UE receives the CSI-RS transmitted by the TX UE. For example, similar to FIG. 8, the time window for SL CSI feedback starts from the minimum preparation time for SL CSI feedback after receiving the CSI-RS. The difference between them is that the reference point of the time window for SL CSI feedback is not a slot that triggers SL CSI feedback, but a slot that transmits CSI-RS, that is, a slot that performs CSI measurement. The slot for performing CSI measurement may be a slot in which SL CSI feedback is triggered or after.

The length unit of the time window for SL CSI feedback is a slot. The measurement of the time window can be absolute slots, ie the length of the time window is the number of all slots contained therein; Alternatively, the measurement of the time window may be relative slots, that is, the length of the time window is the number of slots configured to be available for sidelink transmission included therein, excluding slots not configured to be available for sidelink transmission.

All methods for triggering L1-RSRP feedback described in Embodiment 1 can be similarly applied to triggering SL CSI feedback. For example, periodic SL CSI feedback is triggered through RRC signaling and/or semi-persistent SL CSI feedback with one of a plurality of pre-configured periodic values is triggered through MAC CE. That is, the timing for feeding back SL CSI by the RX UE has a period, and this period may not be completely continuous but may be discontinuous. Alternatively, aperiodic SL CSI feedback is triggered through SCI, that is, the RX UE feeds back the SL CSI once in response to one trigger signaling transmitted by the TX UE. Alternatively, aperiodic SL CSI feedback is triggered through SCI, MAC CE or RRC signaling, that is, the RX UE feeds back the SL CSI multiple times in response to one trigger signaling transmitted by the TX UE.

All methods for feedback of the quantized value of SL L1-RSRP through the MAC CE described in Example 1 can be similarly applied to the SL CSI feedback, that is, the RX UE transmits the measured SL CSI through the MAC CE. Feedback to the UE, the SL CSI includes an SL channel quality indicator (CQI), SL rank information (RI), and/or an SL precoding matrix indicator (PMI). The MAC CE indicating SL CSI may be multiplexed and transmitted with data packets, SL RRC signaling or other MAC CEs, transmitted to the same UE and transmitted on the same PSSCH, or included only in the PSSCH and transmitted.

When the TX UE triggers the SL CSI feedback to the RX UE through SCI, the TX UE transmits the SL CSI-RS in or after the slot triggering the SL CSI feedback, and the RX UE is the SL transmitted by the TX UE. CSI is measured based on the CSI-RS, and the measured CSI is reported to the MAC layer. When there is a PSSCH resource allocated for another transmission within the time window for SL CSI feedback and autonomously allocated by the serving base station or UE, the MAC CE indicating SL CSI is multiplexed with the same PSSCH with other transmissions Can be transmitted through the allocated PSSCH resource; If there is no PSSCH resource allocated within the time window of SL CSI feedback, the sidelink resource must be allocated within the time window of SL CSI feedback for transmission of MAC CE indicating SL CSI. Before preparing for transmission of the PSSCH including the MAC CE indicating SL CSI, when the RX UE receives a new CSI-RS transmitted by the TX UE, the RX UE is the latest CSI-RS transmitted by the TX UE. CSI is measured on the basis of, and the previous SL CSI should be replaced with the latest measured SL CSI.

Optionally, in addition to the indication information on the SL CSI, one MAC CE may further include indication information on the measurement slot position corresponding to the SL CSI, and accordingly, the TX UE is CSI fed back by the RX UE. It is possible to determine which slot of the RS is measured.

In one example, the MAC CE for SL CSI feedback further indicates a gap between the feedback slot of the SL CSI and the corresponding measurement slot, as shown in FIG. 9A. The metric unit of the gap is a slot, that is, the MAC CE indicating SL CSI indicates the number of slots between the feedback slot of the SL CSI and the corresponding measurement slot. Similarly, the metric of the gap may be absolute slots, ie the number of all slots between the feedback slot of the SL CSI and the corresponding measurement slot; Alternatively, the gap metric may be relative slots, that is, the number of slots configured to be available for sidelink transmission between the feedback slot of the SL CSI and the corresponding measurement slot, excluding slots not configured to be available for sidelink transmission. have.

In another example, the MAC CE for SL CSI feedback additionally indicates a gap between the feedback preparation slot of the SL CSI and the corresponding measurement slot, as shown in FIG. 9B. Here, the feedback preparation slot of the SL CSI refers to a time when the RX UE starts preparing to transmit SL CSI, for example, a time when the RX UE starts processing operations such as channel encoding of SL CSI. The gap between the feedback slot of the SL CSI and the corresponding preparation slot is a predefined value, for example, the RX UE starts preparing the transmission process of the SL CSI in the fourth slot before the feedback slot. Similarly, the gap indicated by the MAC CE between the feedback ready slot of the SL CSI and the corresponding measurement slot may include all slots, or may include only all slots configured to be available for sidelink transmission.

In another example, the TX UE sequentially numbers CSI-RSs for temporally transmitted CSI measurement, and transmits the CSI-RS by explicit signaling or implicit signaling, so that the number of CSI-RSs is RX Indicated to the UE, and the MAC CE for SL CSI feedback additionally indicates the number of CSI-RSs measured corresponding to the SL CSI. Here, the number of CSI-RSs is limited in time, and when the number of slots of CSI-RSs transmitted by the TX UE actually exceeds the maximum number, the number of CSI-RSs should start again from 0.

When transmitting the CSI-RS, the TX UE may indicate the number of CSI-RS by a dedicated field included in the SCI in the slot where the CSI-RS is located; Alternatively, the number of CSI-RSs is indicated by the MAC CE included in the PSSCH in the slot in which the CSI-RS is located; Alternatively, the number of CSI-RS is implicitly indicated by the SCI field for triggering CSI-RS feedback, for example, the SCI field for triggering CSI-RS feedback is the pattern of the transmitted CSI-RS May be additionally indicated, and the patterns of a plurality of CSI-RSs for the same SL CSI feedback trigger event transmitted to the same RX UE by the TX UE must be different, and the pattern of the CSI-RS transmitted by the TX UE is The number of CSI-RS can be implicitly indicated.

Priority of SL RRC signaling and/or SL MAC CE transmission

In the LTE V2X system, the SCI includes a field for indicating the priority of the data package transmitted by the associated PSSCH, and this priority is transmitted from the application layer of V2X to the physical layer, whereby the service type of the data package and /Or the priority is determined according to QoS, etc. In the NR V2X system, in addition to the data package, the PSSCH transmitted by the TX UE to the RX UE may further include SL RRC signaling and SL MAC CE, where SL RRC signaling and SL MAC CE are mainly for unicast transmission. , For example, SL RRC signaling is for establishment of a unicast RRC connection state between the TX UE and the RX UE, including higher layer parameter configuration and signaling control, etc., SL MAC CE is the RX UE feedback SL CSI And, it is used to perform processing such as feeding back the SL L1-RSRP to the TX UE or reporting a Power Headroom Report (PHR). When the PSSCH includes only SL RRC signaling and/or SL MAC CE without a data package, the setting of the priority indication value included in the corresponding SCI must be specified.

Optionally, SL RRC signaling and/or MAC CE signaling are transmitted with a predefined or preconfigured priority. For example, PSSCH transmission including SL RRC signaling and/or SL MAC CE has the highest priority, that is, has a priority with a minimum indication value by default, or has the lowest priority, that is, a default It has a priority with the maximum display value, or has a medium priority, i.e., has a priority with an intermediate display value by default. Alternatively, the PSSCH transmission including SL RRC signaling and/or SL MAC CE has a preconfigured priority, and when the UE is an IC, this priority is preconfigured by the serving base station through RRC signaling, and the UE In the case of OOC, this priority is pre-configured in a hard coding scheme by the upper layer sidelink parameter.

When SL RRC signaling and/or SL MAC CE are multiplexed and transmitted on the same PSSCH as the data package, there are several methods for determining the priority of PSSCH transmission. For example, in one example, the priority corresponding to the PSSCH transmission including the data package along with SL RRC signaling and/or SL MAC CE is the priority of the data package and the priority of SL RRC signaling and/or SL MAC CE. Use the higher one in between. In another example, the priority corresponding to the PSSCH transmission including the data package with SL RRC signaling and/or SL MAC CE uses the priority of the data package by default. In another example, the priority corresponding to the PSSCH transmission including the data package with SL RRC signaling and/or SL MAC CE uses the priority of SL RRC signaling and/or SL MAC CE by default.

Optionally, PSSCH transmission including only SL RRC signaling and PSSCH transmission including only SL MAC CE are transmitted with the same priority, that is, SL RRC signaling and SL MAC CE use the same predefined or preconfigured priority; Alternatively, PSSCH transmission including only SL RRC signaling and PSSCH transmission including only SL MAC CE are transmitted with different priorities, that is, SL RRC signaling and SL MAC CE use different predefined or preconfigured priorities.

Optionally, all SL MAC CEs use the same priority, for example, PSSCH transmission including only MAC CE indicating SL CSI and PSSCH transmission including only MAC CE indicating SL L1-RSRP have the same priority. It is transmitted with a priority, ie all SL MAC CEs use the same predefined or preconfigured priority. Alternatively, different SL MAC CEs use different priorities, for example, PSSCH transmission including only MAC CE indicating SL CSI and PSSCH transmission including only MAC CE indicating SL L1-RSRP are different. Transmitted with priorities, ie SL MAC CEs for different purposes use different predefined or preconfigured priorities, respectively.

Example 5: Process for missing input samples in aperiodic SL-RSRP measurement of layer 3 filter

The layer 3 filter of the SL RSRP for power control described above may reuse the layer 3 filter for RRM measurement in the existing Uu system. The existing layer 3 filter is mainly for periodic measurement, but the RS for RSRP measurement transmitted to the RX UE by the TX UE is aperiodic in the V2X system. Therefore, when applying the existing layer 3 filter to aperiodic RSRP measurement, some adaptive processing is required.

The following equation is a layer 3 filter in a conventional Uu system:

이고, 여기서 k는 0,1,2,3,4,5,6,7,8,9,11,13,15,17,19를 포함하는 범위의 필터 계수로 지칭되며, k=0인 경우에는, 계층 3 필터가 수행되지 않고, 즉 계층 1 필터링 이후의 측정 결과가 보고되며 계층 1 필터의 특정 동작들은 UE의 구현에 의존한다.Where M _n is the latest measurement result received from the physical layer; F _n is the latest layer 3 filtered measurement result; F _n-1 is the previous layer 3 filtered measurement result;

Where k is referred to as a filter coefficient in the range including 0,1,2,3,4,5,6,7,8,9,11,13,15,17,19, where k=0 In E, the layer 3 filter is not performed, that is, the measurement result after layer 1 filtering is reported, and specific operations of the layer 1 filter depend on the implementation of the UE.

The above-described layer 3 filter requires that the input frequency of the sample be one sample per X milliseconds, that is, the physical layer reports the latest measurement result to the upper layer every X milliseconds, and X is a predefined value. In the NR Uu system, X is the intra-frequency measurement period defined in 3GPP 38.133, and is related to the frequency range of carriers.

In the NR V2X system, the RS for RSRP measurement transmitted by the TX UE is aperiodic, and the gap between two adjacent RSs for RSRP measurement transmitted by the TX UE may exceed the aforementioned X milliseconds, In that case, RX UE cannot guarantee to measure RSRP at least once per X milliseconds. One sample input frequency per X millisecond can lead to sample dropouts in the layer 3 filter. The standard should clarify and specify these cases.

When the gap between two adjacent RSs for RSRP measurement received by the RX UE exceeds the sample period for the layer 3 filter (i.e., X milliseconds described above), the physical layer is higher from the physical layer of the RX UE. The layer may not have the latest measurement results to report at the specific point in time when the sample should be reported. From this point of view, optionally, the physical layer reports the measurement result reported at the last time point back to the upper layer for layer 3 filtering. Optionally, the physical layer will skip reporting at this time, i.e. if the corresponding input sample is missing and the upper layer has the previously reported measurement result and the latest measurement result to be reported by the physical layer, Estimate the missing intermediate samples based on the latest measurement results reported by For example, the average of the measurement results reported before and after the missing sample is taken as an estimate of the missing sample, and the upper layer is a layer 3 filter based on the most recently reported measurement result and the estimate of the missing intermediate sample. Update the output of Optionally, reporting by the physical layer at this point is skipped, and the upper layer updates the output of the layer 3 filter assuming that the sample value reported at this point is 0.

In an optional manner, avoid the case of missing input samples due to the gap between two adjacent RSs of the RSRP measurement transmitted by the TX UE exceeding the sample period for layer 3 filtering (i.e., X milliseconds described above) To this end, the system specifies that the TX UE transmits an RS for RSRP measurement at least once every 1 millisecond. RS for RSRP measurement is PSSCH DMRS or CSI-RS in which RS for RSRP measurement is not independently transmitted (should be transmitted with PSSCH), that is, RS for RSRP measurement, TX UE is at least every X milliseconds In order to ensure that the RS for RSRP measurement is transmitted once once, assuming that the TX UE can only be transmitted when transmitting the PSSCH to the RX UE, the TX UE transmits the transmission data to be transmitted to the RX UE for X milliseconds. If not, the TX UE must transmit the PSSCH including 0 MAC SDU to the RX UE in order to achieve the purpose of transmitting the RS for RSRP measurement at least once.

Example 6: Under the condition that the TX UE knows the configuration of the layer 3 filter for RSRP at the RX UE side, the TX UE does not signal change information on the transmission power of the RS to the RX UE, and layer 3 filtering at the RX UE side It is possible to change the transmission power of the RS for RSRP measurement within the window.

In the above-described embodiment 2, the RX UE performs layer 3 filtering for SL RSRP, and feeds back the filtered L3-RSRP to the TX UE. In the L3-RSRP filtering window on the RX UE side, the TX UE must keep the transmission power of the RS for RSRP measurement unchanged, so all input samples for L3-RSRP filtering are applied to RSs having the same transmission power. It is measured on the basis of ensuring the accuracy of L3-RSRP. Alternatively, the TX UE may change the transmission power of the RS for RSRP measurement, but must notify the RX UE of the change information on the transmission power of the RS for RSRP measurement, and accordingly, the RX UE The samples reported to the upper layer can be corrected based on the L3-RSRP filtering, and all input samples for generating L3-RSRP filtering become equivalent to those measured based on RSs having the same transmit power, thereby improving the accuracy of L3-RSRP. Can be guaranteed.

Embodiment 2 described above assumes that the TX UE does not know the filter configuration for generating L3-RSRP at the RX UE side. If the TX UE knows the filter configuration for generating L3-RSRP at the RX UE side, the TX UE can know the corresponding coefficient of each input sample for layer 3 filtering at the RX UE side, and thus, based on the transmission power change of RS. Coordination for L3-RSRP may be performed by the TX UE. When the TX UE changes the transmission power of RS for RSRP measurement in the filter window of L3-RSRP, the TX UE does not need to notify the RX UE of change information on the transmission power of RS, and the TX UE transmits the RS. Since both the power change amount and the change time are known, the TX UE can adjust the received L3-RSRP based on the product of the transmit power change amount and the coefficient of the corresponding sample, thereby reducing the sidelink path loss. The accuracy of L3-RSRP for calculation can be guaranteed.

In Embodiment 6, the TX UE may change the transmission power of the RS for RSRP measurement in the filtering window of L3-RSRP at the RX UE side, and the TX UE transmits change information on the transmission power of the RS for RSRP measurement to the RX UE. There is no need to notify. When the TX UE changes the transmission power of RS for RSRP measurement within the filter window of L3-RSRP, the TX UE must adjust the reception L3-RSRP fed back by the RX UE based on the corresponding change amount.

The following equations can be deduced from the equation of the layer 3 filter described above:

임을 알 수 있으며, TX UE가 이 샘플 측정을 위한 RS의 송신 전력을 ΔdB만큼 조정하는 경우, TX UE에 의한 수신 L3-RSRP에 대한 조정량은

이며, 예를 들어, TX UE가 j 번째 샘플 측정을 위한 RS의 송신 전력을 ΔdB만큼 증가시키는 경우, TX UE는 수신된 L3-RSRP로부터

를 빼야 한다.Based on the above equations, the corresponding coefficient for the jth input sample of the filter is

When the TX UE adjusts the transmission power of the RS for this sample measurement by ΔdB, the amount of adjustment for the reception L3-RSRP by the TX UE is

And, for example, when the TX UE increases the transmission power of the RS for the j-th sample measurement by ΔdB, the TX UE from the received L3-RSRP

Should be subtracted.

Embodiment 6 assumes that the TX UE knows the filter configuration for generating L3-RSRP at the RX UE side, including the layer 3 filter coefficient k of samples for filtering and the input period (i.e., the aforementioned X milliseconds) do. In addition, the TX UE and RX UE must consistently understand which slot(s) of RS(s) a particular input sample of the layer 3 filter is measured based on.

Optionally, in order to ensure a consistent understanding between the TX UE and RX UE for the RS whose slot(s) is used for the measurement of the j th input sample, the system sets the first RS for RSRP measurement received by the RX UE. The j-th input sample to be reported to the upper layer using only the physical layer measurement results measured for RSs received in a time window of (j-1)*K to j*K milliseconds, taking the containing slot as a start point Is specified to be created. That is, the j-th input sample reported to the upper layer by the physical layer is the RSRP measurement results after layer 1 filtering within a time window of (j-1)*K to j*K milliseconds. The specific operations of layer 1 filtering depend on the implementation of the UE.

In the existing Uu system, layer 3 filter parameters are configured by the base station and are UE specific, ie the base station can configure different layer 3 filter parameters for different UEs. However, in the NR V2X system, for consistent understanding between the TX UE and RX UE of the layer 3 filter configuration for RSRP at the RX UE side, the configuration method of layer 3 filter parameters may be different from the existing Uu system.

Optionally, layer 3 filter parameters of RSRP for power control at the RX UE side are configured by the TX UE, for example, the TX UE configures layer 3 filter parameters for the RX UE through PC5 RRC signaling. That is, the TX UE and RX UE consistently understand the layer 3 filter configuration.

Optionally, layer 3 filter parameters of RSRP for power control at the RX UE side are configured by sidelink system information, for example, layer 3 filter parameters are configured in the sidelink PBCH. That is, all UEs in the same area have a consistent understanding of the layer 3 filter configuration.

Optionally, layer 3 filter parameters of RSRP for power control at the RX UE side are resource pool specific configurations, for example, layer 3 filter parameters are included in the resource pool configuration information set, and the configured layer 3 filter parameters are the corresponding resource It is used only for RSRP measurements in the pool. That is, all UEs have the same understanding of the layer 3 filter configuration for RSRP measurement in the same resource pool, and different layer 3 filter configurations may be used for RSRP measurement in different resource pools.

In the NR V2X system, the RS for RSRP measurement transmitted by the TX UE to the RX UE is aperiodic, and the TX UE can transmit the RS for RSRP measurement only when transmitting the PSSCH to the RX UE, and then the TX UE The transmission frequency of the RS for RSRP measurement by may be related to the service characteristic, and for this reason, the input period of the RSRP sample for layer 3 filtering in the RX UE (i.e., X milliseconds described above) is also the service of the TX UE. Can be related to characteristics.

Optionally, in addition to the layer 3 filter coefficients, the layer 3 filter configuration at the RX UE side further includes a configuration of an input period (X value) of the sample, that is, the value of X is not fixed but configurable.

Optionally, the value of the layer 3 filter coefficient k at the RX UE side is configured by sidelink system information, and the value of the RSRP input period X of the RSRP sample for layer 3 filtering is configured by the TX UE through PC5 RRC signaling. . The TX UE configures the value of X according to the characteristics of the service transmitted to the RX UE. That is, different RX UEs use the same layer 3 filter coefficient k, but may use different sample input period X milliseconds, and the value of X is associated with the data service characteristic transmitted by the TX UE to the RX UE.

In an optional method, the TX UE can change the transmission power of the RS for RSRP measurement in the layer 3 filtering window of the RX UE side without signaling the change information on the transmission power of the RS to the RX UE, and the transmission power of the RS Do not adjust the received L3-RSRP based on the amount of change in. When the TX UE changes the transmit power of the RS, the TX UE must transmit signaling to trigger a layer 3 filter reset at the RX UE side to ensure the accuracy of L3-RSRP. For example, after the TX UE triggers a layer 3 filter reset on the RX UE side through MAC CE, and after receiving the trigger signaling, the RX UE must perform a layer 3 filter reset, that is, the output of the filter is F ₀ Set to, and re-enter the samples to start layer 3 filtering.

에서 필터의 리셋을 수행하며, 여기서

는 현재 PSSCH에 의해 사용되는 서브캐리어 간격의 경우에 하나의 서브프레임에 포함되는 슬롯의 수이고; 또는 RX UE는 슬롯

에서 필터의 리셋을 수행하고, 여기서 k₁은 계층 3 필터 리셋을 트리거하는 MAC CE를 반송하는 PSSCH의 HARQ-ACK 피드백 시간이며, 즉, HARQ-ACK를 반송하는 PSFCH와 대응하는 PSSCH 사이의 갭이다.In particular, assuming that the RX UE receives the PSSCH carrying the MAC CE triggering the layer 3 filter reset in slot n, the RX UE is

Reset the filter at, where

Is the number of slots included in one subframe in the case of the subcarrier interval currently used by the PSSCH; Or RX UE slot

Performs a filter reset at, where k ₁ is the HARQ-ACK feedback time of the PSSCH carrying the MAC CE that triggers the layer 3 filter reset, that is, the gap between the PSFCH carrying the HARQ-ACK and the corresponding PSSCH. .

에서 또는 그 이후에 SL RSRP를 TX UE에게 보고하고; 또는 RX UE가 슬롯

에서 또는 그 이후에 SL RSRP를 TX UE에게 보고한다.Similarly, the viewpoints apply to the other MAC CE instructions described above, for example, the TX UE triggers the RX UE to report the SL RSRP through the MAC CE, and the MAC triggering the RSRP report in slot n. Assuming that RX CE receives PSSCH carrying CE, TX RS is slot

At or after reporting the SL RSRP to the TX UE; Or RX UE slot

At or after the SL RSRP is reported to the TX UE.

Example 7: TX UE receives L3-RSRP reported by RX UE. L3-RSRP is obtained by the RX UE performing layer 3 filtering of RSRP, which is measured based on the PSSCH DMRS transmitted by the TX UE. The TX UE determines the reference PSSCH DMRS transmission power. The TX UE estimates the sidelink path loss between the TX UE and the RX UE according to the difference between the determined reference PSSCH DMRS transmission power and the received L3-RSRP, and then based on the estimated sidelink path loss between the TX UE and the RX UE. Thus, the transmission power of the PSCCH/PSSCH transmitted to the RX UE is calculated.

Embodiment 7 The PSSCH DMRS transmission power referred to below refers to the transmission power for each resource element of the PSSCH DMRS, that is, the Energy Per Resource Element (EPER), not the total transmission power of the PSSCH DMRS.

The TX UE calculates PSSCH transmission power based on the sidelink path loss according to the following equation.

는 상위 계층을 통해 구성되는, 사이드링크 경로 손실에 기반하는 전력 제어 파라미터들 중 하나인

이고,

는 상위 계층을 통해 구성되는 사이드링크 경로 손실에 기반하는 전력 제어 파라미터들 중 하나인

이고,

는 PSSCH에 의해 차지되는 RB의 수이고, u는 사이드링크 송신에 의해 사용되는 서브캐리어 간격 구성이며,

는 TX UE와 RX UE 사이의 사이드링크 경로 손실이다.here,

Is one of the power control parameters based on the sidelink path loss, which is configured through the upper layer.

ego,

Is one of the power control parameters based on the sidelink path loss configured through the upper layer.

ego,

Is the number of RBs occupied by PSSCH, u is a subcarrier interval configuration used by sidelink transmission,

Is the sidelink path loss between the TX UE and RX UE.

The TX UE estimates the sidelink path loss between the TX UE and the RX UE according to the following equation.

Here, referenceSignalPower is the reference PSSCH DMRS transmission power determined by the TX UE, highLayerFilteredRSRP is the L3-RSRP reported by the RX UE and received by the TX UE, and L3-RSRP is based on the PSSCH DMRS transmitted by the TX UE. It is obtained by the RX UE that performs layer 3 filtering of RSRP, which is measured by the method, and parameters for the layer 3 filter are provided by the configuration parameter filterCoefficient-SL.

In the seventh embodiment, the transmission power of the PSSCH DMRS transmitted from the TX UE to the RX UE may be changed. For example, the transmit power of the PSSCH DMRS transmitted from the TX UE to the RX UE is changed as the sidelink path loss between the TX UE and the RX UE estimated by the TX UE changes. For example, when the TX UE is configured with sidelink power control based on downlink path loss, the transmission power of the PSSCH DMRS transmitted from the TX UE to the RX UE is the downlink path loss estimated by the TX UE (i.e., It may be changed as the path loss between the TX UE and the base station) changes.

When the transmission power of the PSSCH DMRS transmitted from the TX UE to the RX UE is not changed for a long time, the TX UE uses the actual transmission power of the PSSCH DMRS transmitted to the RX UE as the reference PSSCH DMRS transmission power for sidelink path loss estimation. You can take it. When the transmission power of the PSSCH DMRS transmitted from the TX UE to the RX UE is changed, how the TX UE determines the reference PSSCH DMRS transmission power for sidelink path loss estimation becomes a problem.

In an alternative method, the TX UE performs an Exponential Weighted Moving Average (EWMA) of the actual transmission power samples of the PSSCH DMRS transmitted to the RX UE by the TX for a certain period of time to determine the reference PSSCH DMRS transmission power for sidelink path loss estimation. You can decide.

For example, the TX UE determines the reference PSSCH DMRS transmit power using the following EWMA equation, which is similar to the principle of the layer 3 filter for RSRP:

는 시점 n에서 계산된 기준 PSSCH DMRS 송신 전력, 즉, 전술한 사이드링크 경로 손실 추정을 위한 referenceSignalPower이며,

는 시점 n에서 RX UE에 송신되는 PSSCH DMRS의 실제 송신 전력이며, 대응하는 가중 계수는 0~1의 값 범위를 갖는 b이고,

는 시점 n-j에서 RX UE로 송신되는 PSSCH DMRS의 실제 송신 전력이며, 대응하는 가중 계수는

이다.here,

Is the reference PSSCH DMRS transmission power calculated at time n, that is, the referenceSignalPower for estimating the aforementioned sidelink path loss,

Is the actual transmission power of the PSSCH DMRS transmitted to the RX UE at time n, and the corresponding weighting factor is b having a value range of 0 to 1,

Is the actual transmit power of the PSSCH DMRS transmitted to the RX UE at time nj, and the corresponding weighting factor is

to be.

In the EWMA equation, samples at different time points correspond to different weighting factors, and moving averages are obtained based on the different weighting factors. Here, the weighting coefficients for each sample decrease exponentially with time, and the closer the sample is to the current time point, the larger the corresponding weighting coefficients become, i.e., the closer the sample is to the current time point, the greater the moving average. Its contribution increases.

In the EWMA equation, the weighting factors for the actual transmit power of the PSSCH DMRS transmitted to the RX UE at different times are different, and the weighting factor is associated with the distance to time n. The further the PSSCH DMRS is transmitted to the RX UE with respect to time n, the smaller the weighting factor for the actual transmit power. The closer to the point n when the PSSCH DMRS is transmitted to the RX UE, the greater the weighting factor for the actual transmission power.

와 완전히 동일할 수 있으며, 즉

이고, 여기서

는 계층 3 필터의 구성 파라미터 filterCoefficient-SL에 의해 제공되는 0,1,2,3,4,5,6,7,8,9,11,13,15,17,19의 값 범위를 갖는 필터 계수로 지칭된다.It can be understood from the layer 3 filter described above (in Embodiment 6) that the EWMA equation for determining the reference PSSCH DMRS transmission power is very similar to the principle of the layer 3 filter. Parameter b of the EWMA equation for determining the reference PSSCH DMRS transmission power is a parameter in the equation of the layer 3 filter described above

Can be exactly the same as

Is, where

Is a filter coefficient with a value range of 0,1,2,3,4,5,6,7,8,9,11,13,15,17,19 provided by the configuration parameter filterCoefficient-SL of the layer 3 filter Is referred to as.

That is, under the condition that the TX UE knows the parameter configuration of the layer 3 filter used by the L3-RSRP reported by the RX UE, the TX UE is the layer 3 filter used by the L3-RSRP reported by the RX UE. The reference PSSCH DMRS transmission power is determined by determining a corresponding weighting factor based on the parameter configuration filterCoefficient-SL. In Embodiment 6, there are a number of configuration methods for the filter parameter to realize this condition, for example, the TX UE configures the filterCoefficient-SL for the RX UE through PC5 RRC signaling, alternatively, filterCoefficient-SL is configured based on the resource pool.

In addition, the sample interval for determining the reference PSSCH DMRS transmission power may be completely the same as the sample interval for the layer 3 filter, that is, the sample period (X milliseconds) of the layer 3 filter, and the TX UE is PSSCH DMRS per millisecond. One value of the actual transmit power of may be provided as one input sample to the EWMA.

Alternatively, in order to improve the accuracy of sidelink path loss estimation, the TX UE keeps the actual transmission power of the PSSCH DMRS as constant as possible for at least X milliseconds, and then the value of the actual transmission power of the PSSCH DMRS is X milliseconds. It may be regarded as an input sample for EWMA to determine the reference PSSCH DMRS transmit power for seconds. Even if the downlink path loss and/or sidelink path loss changes, the TX UE ensures that the actual transmit power of the PSSCH DMRS does not change for X milliseconds, and the changed downlink path loss and/or side after X milliseconds. The actual transmission power of the PSSCH DMRS must be changed based on the link path loss, that is, the minimum time granularity for the TX UE to adjust the actual transmission power of the PSSCH DMRS is X milliseconds.

Alternatively, if the actual transmit power of the PSSCH DMRS changes for X milliseconds due to the change in downlink path loss and/or sidelink path loss, then the input sample for EWMA to determine the reference PSSCH DMRS transmit power for X milliseconds. The value of may depend on the implementation of the TX UE, for example, the TX UE may consider the average of the actual transmission powers of the PSSCH DMRS for X milliseconds as the aforementioned input sample.

Alternatively, assuming that the TX UE receives the L3-RSRP reported by the RX UE at time t, the TX UE is transmitted to the RX UE within a window [t-T2, t-T1] before time t. The reference PSSCH DMRS transmission power is determined based on the EWMA of the actual transmission powers of the PSSCH DMRSs. Here, T2>T1≥0, T1 and T2 may be predefined or preconfigured values, where the value for T1 may include the physical consumption time for reporting L3-RSRP; Alternatively, the length of the window T2-T1 is a predefined or preconfigured value, for example, the length of the window may be predefined or preconfigured as 10 seconds. When the TX UE does not transmit the PSSCH to the RX UE in the first period within the window [t-T2, t-T1], the TX UE is for input samples, the subsequence period within the window [t-T2, t-T1] Only the actual transmission powers of the PSSCH DMRS transmitted from the TX UE to the RX UE can be used.

Alternatively, assuming that the TX UE receives the L3-RSRP reported by the RX UE at time t, the TX UE is transmitted to the RX UE within a window [t-0, t-T1] before time t The reference PSSCH DMRS transmission power is determined based on the EWMA of the transmission powers of the PSSCH DMRS. Here, T1≥0, T1 may be a predefined or preconfigured value, and the value of T1 may include a physical consumption time for reporting L3-RSRP; t0 is the time when the TX UE establishes the PC5 RRC connection with the RX UE, i.e., until the time t-T1 before the L3-RSRP is received, a certain time from the time t0 when the TX UE establishes a PC5 RRC connection with the RX UE The actual transmission powers of all PSSCH DMRSs transmitted from the TX UE to the RX UE are used for EWMA during the period.

The above-described method of determining the reference PSSCH DMRS transmission power by performing EWMA of the actual transmission powers of the PSSCH DMRS can also be understood as determining the reference PSSCH DMRS transmission power by filtering the actual transmission powers of the PSSCH DMRS, and the output of the filter. This is the reference PSSCH DMRS transmission power, and the filter for the PSSCH DMRS transmission power at the TX UE side may use the same filter configuration parameters as the layer 3 filter of the RSRP at the RX UE side.

Alternatively, the physical layer (i.e., layer 1) in the TX UE determines the reference PSSCH DMRS transmission power by the above method, which is completely similar to the RSRP filtering principle of layer 3 in the RX UE, but the performing entities The layers to which they belong are different, that is, the former is performed by layer 1 in the TX UE, and the latter is performed by layer 3 in the RX UE. The above-described method may also be referred to as layer 1 filtering of PSSCH DMRS transmission power.

Alternatively, the upper layer (i.e., layer 3) in the TX UE determines the reference PSSCH DMRS transmission power by the above-described method, which is completely similar to the RSRP filtering principle of layer 3 in the RX UE, and the performing entities The layers to which they belong are the same, i.e. both are performed by layer 3. The above-described method may also be referred to as layer 3 filtering of PSSCH DMRS transmission power.

In another alternative scheme, the TX UE determines the reference PSSCH DMRS transmit power by performing EWMA of the actual transmit powers of the PSSCH DMRSs, and the specific weighting factors depend on the implementation of the TX UE. That is, the TX UE determines the above-described reference PSSCH DMRS transmission power by an EWMA method similar to the layer 3 filtering principle of RSRP, and the TX UE is the same filter as the layer 3 filter used by the L3-RSRP reported by the RX UE. The parameter can be used to determine weighting factors; The TX UE may also determine the weighting factor using a filter parameter different from that for the layer 3 filter used by L3-RSRP reported by the RX UE.

In another alternative scheme, the method of determining the reference PSSCH DMRS transmit power depends on the implementation of the TX UE. For example, the TX UE may determine the reference PSSCH DMRS transmit power by EWMA; Alternatively, the TX UE may calculate a linear weighted average of samples within a time window having a fixed length, and consider the obtained average as the reference PSSCH DMRS transmission power.

Those of skill in the art will understand that the present invention includes devices related to performing one or more of the operations described in this disclosure. These devices may be specially designed and manufactured for the required purpose, or may include devices known to general purpose computers. These devices store computer programs that are selectively activated or reconfigured. Such computer programs may be stored on device (e.g., computer) readable media, or floppy disks, hard disks, optical disks, CD-ROMs and magneto-optical disks, read-only memory (ROM), random access (RAM) Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, magnetic card, or light card, including, but not limited to, any type of disk, electronic instructions Can be stored on any type of medium suitable for storing them and coupled to the bus. That is, the readable medium includes any medium that stores or transmits information in a form readable by an apparatus (eg, a computer).

Those skilled in the art can understand that each block of these structural diagrams and/or block diagrams and/or flowcharts, and combinations of blocks of these structural diagrams and/or block diagrams and/or flowcharts, may be implemented by computer program instructions. . Those skilled in the art may provide these computer program instructions to a processor of a general-purpose computer, a specialized computer, or a processor for other programmable data processing methods, and are thus specified in one or more blocks of a structural diagram and/or block diagram and/or flowchart. It will be appreciated that the schemes may be executed by a computer or a processor of a computer for other programmable data processing methods.

Those of skill in the art will understand that the various operations, methods, steps, measurements, and manners discussed in this disclosure may be substituted, altered, combined, or deleted. In addition, other steps, measurements, and manners in the various operations, methods, and processes discussed in this disclosure may also be replaced, altered, rearranged, disassembled, combined, or deleted. In addition, various operations, methods, steps, measurements and methods of the prior art and those disclosed in the present invention may also be replaced, altered, rearranged, disassembled, combined or deleted.

The foregoing is only some of the embodiments of the present invention. It should be noted that some of the improvements and improvements may be made to those skilled in the art without departing from the principles of the present invention, and these improvements and improvements should also be regarded as the protection scope of the present invention.

Claims (15)

In the method of the first terminal of the communication system,
Transmitting sidelink control information (SCI) including an information field related to a request for sidelink channel state information (CSI) to a second terminal;
Transmitting a sidelink channel state information reference signal (CSI-RS) to the second terminal in response to the information field indicating a request for a sidelink CSI; And
And receiving a sidelink CSI obtained based on the sidelink CSI-RS from the second terminal. The method of claim 1,
The sidelink CSI method, characterized in that received through a MAC (medium access control) control element (CE: control element). The method of claim 2,
The method of claim 1, wherein the priority of the MAC CE is a predefined value. The method of claim 1,
The sidelink CSI includes a rank indicator (RI) and channel quality information (CQI) excluding a precoding matrix indicator (PMI). In the method of the second terminal of the communication system,
Receiving sidelink control information (SCI) including an information field related to a request for sidelink channel state information (CSI) from a first terminal;
Receiving a sidelink channel state information reference signal (CSI-RS) from the first terminal in response to the information field indicating a request for a sidelink CSI; And
And transmitting a sidelink CSI obtained based on the sidelink CSI-RS to the first terminal. The method of claim 5,
The sidelink CSI is characterized in that it is transmitted through a medium access control (MAC) control element (CE control element). The method of claim 6,
The method of claim 1, wherein the priority of the MAC CE is a predefined value. The method of claim 5,
The sidelink CSI includes a rank indicator (RI) and channel quality information (CQI) excluding a precoding matrix indicator (PMI). In the first terminal of the communication system,
A transceiver; And
Sidelink control information (SCI: sidelink control information) including an information field related to a request for sidelink channel state information (CSI) is transmitted to the second terminal, and the information field indicates a request for a sidelink CSI. In response to the indication, a sidelink channel state information reference signal (CSI-RS) is transmitted to the second terminal, and the sidelink CSI obtained based on the sidelink CSI-RS is transmitted to the second terminal. A first terminal comprising a control unit configured to receive from 2 terminals. The method of claim 9,
The first terminal, characterized in that the sidelink CSI is received through a medium access control (MAC) control element (CE). The method of claim 10,
The first terminal, characterized in that the priority of the MAC CE is a predefined value. The method of claim 9,
The first terminal, wherein the sidelink CSI includes a rank indicator (RI) and channel quality information (CQI) excluding a precoding matrix indicator (PMI). In the second terminal of the communication system,
A transceiver; And
Sidelink control information (SCI: sidelink control information) including an information field related to a request for sidelink channel state information (CSI) is received from a first terminal, and the information field is a request for a sidelink CSI. In response to the indication, a sidelink channel state information reference signal (CSI-RS) is received from the first terminal, and the sidelink CSI obtained based on the sidelink CSI-RS is received. A second terminal comprising a control unit configured to transmit to one terminal. The method of claim 13,
The sidelink CSI is transmitted through a medium access control (MAC) control element (CE: control element),
The second terminal, characterized in that the priority of the MAC CE is a predefined value. The method of claim 13,
The second terminal, wherein the sidelink CSI includes a rank indicator (RI) and channel quality information (CQI) excluding a precoding matrix indicator (PMI).

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