Terminal device and terminal device method

Abstract

To provide a method for enabling determination of side link channel path loss for open loop power control in a side link channel transmitting terminal device.SOLUTION: In a communication process 200, a first terminal device generates a measurement report by measuring a reference signal from a second terminal device via a side link channel, determines whether to transmit the measurement report to the second terminal device on the basis of a reporting criterion, and transmits the measurement report to the second terminal device in response to the determination to send the measurement report. The second terminal device determines the path loss of the side link channel on the basis of the measurement report.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD Embodiments of the present disclosure relate generally to the field of communications, and more particularly to solutions for sidelink power control. [Background technology]

[0002] The most recent evolution of the 3GPP standard is called the Long Term Evolution (LTE) of the Evolved Packet Core (EPC) network and the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), commonly referred to as "4G." The term "5G New Radio (NR)" also refers to a continuously evolving communications technology that is expected to support a variety of applications and services. 5G NR is part of the continuing evolution of mobile broadband announced by the Third Generation Partnership Project (3GPP) and is intended to meet new requirements associated with latency, reliability, security, scalability (e.g., the Internet of Things), and other requirements. Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Summary of the Invention [Problem to be solved by the invention]

[0003] The recent 3GPP meeting has already allowed the following: For a unicast receiving (RX) user equipment (UE), reporting the sidelink (SL) reference signal received power (RSRP) to the transmitting (TX) UE; For sidelink open loop power control for TX UE unicast, the TX UE derives a path loss estimate; For SL open loop power control, the UE is configured to use only the downlink (DL) path loss (between the TX UE and the gNB), only the SL path loss (between the TX UE and the RX UE), or both the DL and SL path losses; However, the details and procedures of the various operations for the sidelink power control of the RX UE and the TX UE are still unclear and need clarification.

[0004] Generally, the exemplary embodiments of the present disclosure provide a solution for sidelink power control. [Means for solving the problem]

[0005] In a first aspect, a method for communication is provided, the method including: generating, at a first terminal device, a measurement report by measuring a reference signal from a second terminal device via a sidelink channel; determining, based on a reporting criterion, whether to transmit the measurement report to the second terminal device; and, in response to determining the transmission of the measurement report, transmitting the measurement report to the second terminal device, thereby causing the second terminal device to determine a path loss of the sidelink channel based on the measurement report.

[0006] In a second aspect, a method for communications is provided, the method including: transmitting, at a second terminal device, via a sidelink channel, a plurality of reference signals to a first terminal device over a time window; determining an average received power of the plurality of reference signals measured by the first terminal device over the time window; and determining a path loss of the sidelink channel based on a difference between the average received power and an average transmitted power of the plurality of reference signals.

[0007] In a third aspect, a method for communications is provided, the method including: receiving, at a second terminal device, a measurement report from the first terminal device for reporting a received power of a reference signal measured by the first terminal device, the reference signal being transmitted from the second terminal device to the first terminal device via a sidelink channel; determining a transmit power of the reference signal; and determining a path loss of the sidelink channel based on the received power and the transmit power.

[0008] In a fourth aspect, a method for communication is provided, the method including, at a second terminal device, transmitting information to a first terminal device, the first terminal device performing Layer 3 filtering on received power of a reference signal measured by the first terminal device, the reference signal being transmitted from the second terminal device to the first terminal device via a sidelink channel, receiving a measurement report from the first terminal device reporting the filtered received power, and determining a path loss of the sidelink channel based on the information and the filtered received power.

[0009] In a fifth aspect, there is provided a first terminal device, the first terminal device including a processor and a memory for storing instructions, the memory and the instructions, together with the processor, configured to cause the first terminal device to perform a method according to the first aspect.

[0010] In a sixth aspect, there is provided a second terminal device, the second terminal device comprising a processor and a memory for storing instructions, the memory and the instructions, together with the processor, configured to cause the second terminal device to perform a method according to the second, third or fourth aspect.

[0011] In a seventh aspect, there is provided a computer readable medium having stored thereon instructions which, when executed by at least one processor of a device, cause the device to perform a method according to the first, second, third or fourth aspect.

[0012] The Summary section herein is not intended to identify key or required features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description. [Brief explanation of the drawings]

[0013] These and other objects, features and advantages of the present disclosure will become apparent from a more detailed description of several embodiments of the present disclosure in the drawings.

[0014] [Figure 1] FIG. 1 is a schematic diagram of a communication environment in which some embodiments of the present disclosure may be implemented.

[0015] [Figure 2] 1 illustrates an exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0016] [Figure 3] 10 illustrates another exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0017] [Figure 4A] 1 illustrates an exemplary scenario in which a first terminal device according to some embodiments of the present disclosure transmits respective measurement reports of multiple reference signals to a second terminal device.

[0018] [Figure 4B] Illustrated is an example scenario in which a first terminal device according to some embodiments of the present disclosure transmits a single measurement report to a second terminal device for reporting average received power of multiple reference signals.

[0019] [Figure 5A] 10 illustrates another exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0020] [Figure 5B] 10 illustrates another exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0021] [Figure 6] 10 illustrates another exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0022] [Figure 7] 1 illustrates an example resource distribution for transmitting a reference signal and associated measurement reports according to some embodiments of the present disclosure, where the measurement reports are transmitted on a PSFCH associated with a PSSCH associated with the reference signal.

[0023] [Figure 8] 1 illustrates another example resource distribution for transmitting reference signals and associated measurement reports according to some embodiments of the present disclosure, where two ordered sets of time-frequency resources transmit reference signals and associated measurement reports.

[0024] [Figure 9] 10 illustrates another example resource distribution for transmitting reference signals and associated measurement reports according to some embodiments of the present disclosure, where the measurement reports include time information of the associated reference signals.

[0025] [Figure 10] 10 illustrates another exemplary communication process between a first terminal device and a second terminal device according to some embodiments of the present disclosure.

[0026] [Figure 11] 1 is a flowchart of an exemplary method according to some embodiments of the present disclosure.

[0027] [Figure 12] 1 is a flowchart of another exemplary method according to some embodiments of the present disclosure.

[0028] [Figure 13] 1 is a flowchart of another exemplary method according to some embodiments of the present disclosure.

[0029] [Figure 14] 1 is a flowchart of another exemplary method according to some embodiments of the present disclosure.

[0030] [Figure 15] FIG. 1 is a simplified block diagram of an apparatus capable of implementing some embodiments of the present disclosure.

[0031] Throughout the drawings, the same or similar reference numbers refer to the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0032] The principles of the present disclosure will now be described with reference to some exemplary embodiments. However, these embodiments do not represent any limitation on the scope of the present disclosure, but are merely for the purpose of explanation and for those skilled in the art to understand and practice the present disclosure. The present disclosure described herein can be implemented in various forms other than those described below.

[0033] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0034] For example, the terms "network device" or "base station" (BS) used herein refer to a device that provides or accommodates a cell or coverage area over which terminal devices can communicate. Examples of network devices include, but are not limited to, a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gNB), infrastructure devices for V2X communications, a Transmission / Reception Point (TRP), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), and a low-power node (e.g., a femto node, a pico node, etc.).

[0035] For example, the term "terminal device" as used herein refers to any device having wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user equipment (UE), in-vehicle terminal devices, pedestrian devices, roadside units, personal computers, desktop computers, mobile phones, cellular phones, smartphones, personal digital assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback devices, or Internet devices enabling wireless or wired Internet access and browsing. For purposes of discussion, some embodiments will be described below with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably in the specification of this disclosure.

[0036] In one embodiment, a terminal device is connected to a first network device and a second network device. One of the first network device and the second network device is a master node, and the other is a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device is a first RAT device, and the second network device is a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information regarding the different RATs is transmitted to the terminal device from at least one of the first network device and the second network device. In one embodiment, the first information is transmitted from the first network device to the terminal device, and the second information is transmitted from the second network device directly or via the first network device to the terminal device. In one embodiment, information regarding the configuration of the terminal device configured by the second network device is transmitted from the second network device via the first network device. Information regarding the reconfiguration of the terminal device configured by the second network device is transmitted to the terminal device from the second network device directly or via the first network device.

[0037] As used herein, the singular forms "a," "an," and "said" are intended to include the plural forms as well, unless expressly indicated otherwise. The term "comprises" and variations thereof are understood as open terms, meaning "including, but not limited to." The term "based on" is understood as "based at least in part on." The terms "in one embodiment" and "embodiment" are understood as "at least one embodiment." The term "another embodiment" is understood as "at least one other embodiment." The terms "first," "second," etc., refer to different or identical objects. Other definitions (explicit and implicit) may be included below.

[0038] In some instances, values, programs, or devices are referred to as "optimal," "lowest," "highest," "minimum," "maximum," etc. Such designations indicate that a choice may be made from among many functional alternative solutions to be used, and that such a choice is not necessarily better, smaller, higher, or otherwise more preferred than other choices.

[0039] 1 is a schematic diagram of a communication environment 100 in which some embodiments of the present disclosure can be implemented. As shown in FIG. 1, a first terminal device 110 and a second terminal device 120 are both within the coverage of a network device 130. In other words, the network device 130 can serve and provide wireless connectivity to the first terminal device 110 and the second terminal device 120. Specifically, the first terminal device 110 can communicate with the network device 130 via a communication channel 105, and the second terminal device 120 can communicate with the network device 130 via a communication channel 115. For transmissions from the network device 130 to the first terminal device 110 or the second terminal device 120, the communication channel 105 or the communication channel 115 is referred to as a downlink channel, and for transmissions from the first terminal device 110 or the second terminal device 120 to the network device 130, the communication channel 105 or the communication channel 115 is alternatively referred to as an uplink channel.

[0040] Additionally, the first terminal device 110 can communicate with the second terminal device 120 via a device-to-device (D2D) channel 125, which is also referred to as a sidelink channel 125. In some cases, the network device 130 may not be present in the communication environment 100. For example, the first terminal device 110 and the second terminal device 120 are outside the coverage of the network device 130. In this case, only sidelink communication exists between the first terminal device 110 and the second terminal device 120, and possibly other terminal devices not shown in FIG.

[0041] In some embodiments, during a sidelink communication period between the first terminal device 110 and the second terminal device 120 via the sidelink channel 125, the second terminal device 120 transmits a reference signal 135 to the first terminal device 110 using a first set of transmission resources. For example, the term "reference signal" as used herein refers to a known signal of a transmitting device and a receiving device, and can be used to perform channel estimation, channel sounding, and the like. Generally, the term "reference signal" as used herein includes any conventional or future reference signal defined in various standards or specifications (e.g., 3GPP specifications). Upon receiving the reference signal 135, the first terminal device 110 measures the reference signal 135 to obtain a measurement result of the reference signal 135, such as the received power and reception quality of the reference signal 135.

[0042] Then, the first terminal device 110 generates a measurement report 155 based on the measurement result of the reference signal 135. For example, the measurement report 155 includes information indicating the received power of the reference signal 135 measured by the first terminal device 110. The first terminal device 110 then transmits the measurement report 155 to the second terminal device 120 using a second set of transmission resources. Based on the measurement report 155, the second terminal device 120 obtains channel information of the sidelink channel 125. For example, the second terminal device 120 determines a path loss of the sidelink channel 125 based on the transmit power of the reference signal 135 and the received power of the reference signal 135 reported by the first terminal device 110.

[0043] For example, the terms "resource," "transmission resource," or "sidelink resource" used herein refer to any resource for performing communication (e.g., sidelink communication between communication devices), such as a resource in the time domain (e.g., time slot), a resource in the frequency domain (e.g., subchannel), a resource in the spatial domain, a resource in the code domain, or any other resource for realizing communication. Hereinafter, some embodiments of the present disclosure will be described by taking resources in the frequency domain and the time domain as examples of sidelink resources. However, the embodiments of the present disclosure also apply to other resources in other domains.

[0044] For example, as defined in the 3GPP specifications, the measurement result obtained by the first terminal device 110 measuring the reference signal 135 is called a layer 1 (i.e., physical layer) measurement result. Before reporting the measurement result to the second terminal device 120, the first terminal device 110 performs layer 3 filtering on the layer 1 measurement result to obtain a filtered measurement result and reports it to the second terminal device 120. Alternatively, when the first terminal device 110 reports the layer 1 measurement result to the second terminal device 120, before determining the path loss, the second terminal device 120 performs layer 3 filtering on the layer 1 measurement result to obtain a filtered measurement result and determine the path loss. For example, layer 3 filtering is performed based on the following equation (1):

number

[0045] Although the communication environment 100 of FIG. 1 illustrates a first terminal device 110, a second terminal device 120, and a network device 130, embodiments of the present disclosure equally apply to any other suitable communication devices communicating with each other. That is, embodiments of the present disclosure are not limited to the exemplary scenario of FIG. 1. In this regard, although the first terminal device 110 and the second terminal device 120 are schematically illustrated as mobile phones in FIG. 1, this illustration is not limiting and is merely exemplary. In other embodiments, the first terminal device 110 and the second terminal device 120 may be any other wireless communication device, for example, a vehicle-mounted terminal device.

[0046] When the first terminal device 110 and the second terminal device 120 are in-vehicle terminal devices, communication between the first terminal device 110 and the second terminal device 120 is referred to as V2X communication. More specifically, although not shown in FIG. 1 , V2X communication between the first terminal device 110 or the second terminal device 120 may include communication between the first terminal device 110 or the second terminal device 120 and any other communication device, including, but not limited to, an infrastructure device, another in-vehicle terminal device, a pedestrian device, a roadside device, etc. Also, although not shown, all communication links in FIG. 1 may go through one or more relays.

[0047] 1 are not intended to be limiting and are merely for illustrative purposes. Communication environment 100 may include any suitable number of terminal devices, any suitable number of network devices, and any suitable number of other communication devices capable of implementing embodiments of the present disclosure. Also, various wireless and wired communications may exist (if necessary) between all of the communication devices.

[0048] Communications in communication environment 100 may conform to any suitable standard, including, but not limited to, Global System for Mobile Communication (GSM), Extended Coverage Global System for Mobile Internet of Things (EC-GSM-IoT), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), etc. Additionally, communications may be performed in accordance with any currently known or future-developed generation of communication protocols. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communication protocols.

[0049] As described above, in the conventional solutions, the details and procedures of various operations for sidelink power control of the RX UE and the TX UE are still unclear and need to be clarified. Specifically, in conventional LTE sidelink communication, SL-RSRP is used for, for example, synchronization source search and resource detection. Additionally, in conventional LTE / NR uplink power control, RSRP performs path loss estimation. These conventional solutions do not define the RSRP to be transmitted / reported to other UEs.

[0050] In contrast, in NR sidelink communication, for unicast RX UEs (which also applies to multicast or broadcast RX UEs), reporting of SL-RSRP to TX UEs is required to determine sidelink path loss. However, there are some issues with measurement reporting for reporting reference signals in sidelink communication. For example, in traditional solutions, the timing of RSRP measurement and reporting at the RX UE is not defined, and some timing may be unnecessary.

[0051] In NR sidelink communication, the transmit power of a reference signal from a TX UE (represented by the energy of each resource element EPRE) may vary from time slot to time slot through transmit power control. Furthermore, the time domain order of measurement reports transmitted by a RX UE may differ from the reference signal transmission order, which may cause the RX UE to miss some reference signals. Therefore, the TX UE does not know the transmit power of the reference signal associated with the received measurement report.

[0052] In addition, it is unclear when and where to send the SL-RSRP to the TX UE. For example, it is unclear which channel and which transmission resource the RX UE uses to send the measurement report. It is unclear whether the RX UE sends the measurement report when it generates the measurement report or based on periodicity.

[0053] In summary, in traditional solutions, in some cases, reference signal measurements and measurement reports may not be required, and when a TX UE receives a measurement report from a RX UE, the transmit power (e.g., EPRE) associated with the reference signal is unclear.

[0054] To solve the above technical problems and other technical problems that may exist in conventional solutions, embodiments of the present disclosure provide a solution for sidelink power control. In some embodiments, measurement behavior of reference signals and measurement reports at the TX UE and the RX UE are specified. In some embodiments, Layer 3 filtering can be performed at the TX UE, and the average transmit power and average receive power within a time window are used to determine the path loss. For example, the RX UE reports each measurement result, and the TX UE calculates the average transmit power and average receive power. Alternatively, the RX UE reports the average receive power, and the TX UE calculates the average transmit power.

[0055] In some embodiments, Layer 3 filtering can be performed at the TX UE, with a one-to-one mapping between reported measurements and reference signals. For example, the mapping between measurement reports and reference signals can be implicitly indicated by distinguishing transmission resources. Alternatively, the mapping can be explicitly indicated by indicating the time point of the reference signal transmission. In some embodiments, Layer 3 filtering can be performed at the RX UE. The TX UE indicates transmit power information (e.g., reference transmit power and / or actual transmit power) to the RX UE, and the RX UE performs L3 filtering using the normalized received power.

[0056] According to the embodiments of the present disclosure, more effective and efficient measurement reports can be obtained, and the path loss in the sidelink channel can be more accurately determined, which can be used for controlling the transmit power in the sidelink communication. The principles and embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0057] 2 illustrates an exemplary communication process 200 between a first terminal device 110 and a second terminal device 120 in accordance with some embodiments of the present disclosure. For purposes of discussion, communication process 200 is described with reference to FIG. 1, although communication process 200 here also applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0058] As shown in Fig. 2, the second terminal device 120 transmits a reference signal 135 to the first terminal device 110 via the sidelink channel 125 at 210. As described above, the reference signal 135 can perform channel estimation, channel probing, etc. Therefore, the first terminal device 110 measures the reference signal 135 at 210 and generates a measurement report 155 at 215 based on the measurement result of the reference signal 135. In other words, the first terminal device 110 measures the reference signal 135 at 210 and generates the measurement report 155 at 215.

[0059] In some embodiments, to avoid unnecessary measurement of the reference signal, the first terminal device 110 uses a measurement criterion to determine whether to measure the reference signal 135 at 210 and generate the measurement report 155 at 215. In other words, the first terminal device 110 determines whether to measure the reference signal 135 at 210 based on the measurement criterion and generates the measurement report 155 at 215. If it is decided to measure the reference signal 135, the terminal device 110 measures the reference signal 135 at 210 and then generates the measurement report 155. In this way, the first terminal device 110 does not always measure the reference signal transmitted from the second terminal device 120. In fact, when measurement of the reference signal 135 is required, the first terminal device 110 measures the reference signal 135, thereby improving the efficiency of the measurement report 155 and saving processing resources and other resources for performing measurements at the first terminal device 110.

[0060] In general, the metric may be any suitable metric that allows the first terminal device 110 to avoid unnecessary measurements of the reference signal. In some embodiments, the metric allows the second terminal device 120 to perform transmit power control using the path loss of the sidelink channel 125. For example, if the second terminal device 120 is configured to perform transmit power control using only the path loss of the sidelink channel 125, or to perform transmit power control using the path loss of the downlink channel 115 and the path loss of the sidelink channel 125, the first terminal device 110 can measure the reference signal 135.

[0061] Otherwise, if the second terminal device 120 is configured to perform transmit power control using only the path loss of the downlink channel 115, the measurement report 155 of the reference signal 135 in the sidelink channel 125 is disabled for the second terminal device 120, which in turn disables the first terminal device 110 from measuring the reference signal 135. In some embodiments, an indication to indicate whether the second terminal device 120 should use the path loss of the sidelink channel 125 is transmitted from the second terminal device 120 or the network device 130 to the first terminal device 110, e.g., via higher layer signaling.

[0062] Alternatively or additionally, the metric may be that the estimated path loss (or radio distance) of the sidelink channel 125 is below a configurable threshold (also referred to as a first threshold). As used herein, the term "radio distance" between two devices refers to the distance between the two devices in terms of radio communication. For example, if there are obstacles in the radio communication path between the two devices that may affect radio communication, the radio distance between the two devices may be longer than the actual geographical distance between them. Therefore, the estimated path loss of the sidelink channel 125 can be obtained based on the radio distance between the first terminal device 110 and the second terminal device 120. In this case, if the estimated path loss is below the first threshold, the first terminal device 110 determines to measure the reference signal 135. Otherwise, if the estimated path loss is above the first threshold, the first terminal device 110 determines not to measure the reference signal 135.

[0063] According to the agreement of the recent 3GPP conference, when the SL open-loop power control is configured to use the DL path loss and the SL path loss, the minimum power value from the open-loop power control based on the DL path loss and the open-loop power control based on the SL path loss is adopted. Therefore, if the wireless distance between the first terminal device 110 and the second terminal device 120 is large, the power value from the open-loop power control may become large. In this case, the second terminal device 120 may not control the transmission power using the path loss of the sidelink channel 125. In this case, it may be necessary to measure the reference signal 135.

[0064] In some embodiments, the indication to indicate whether the estimated path loss of the sidelink channel 125 is below the first threshold is transmitted from the network device 130, e.g., via RRC signaling, or from the second terminal device 120, e.g., via a field in sidelink control information (SCI), to the first terminal device 110. In other embodiments, the first terminal device 110 may make the decision to estimate whether the path loss is below the first threshold, since the first terminal device 110 may know the radio distance between itself and the second terminal device 120.

[0065] Alternatively or additionally, the measurement criterion is that the path loss (or wireless distance) of the communication channel 115 between the second terminal device 120 and the network device 130 exceeds a configurable threshold (also referred to as a second threshold). In other words, if the path loss of the communication channel 115 exceeds the second threshold, the first terminal device 110 decides to measure the reference signal 135. Otherwise, if the path loss of the communication channel 115 is below the second threshold, the first terminal device 110 decides not to measure the reference signal 135.

[0066] This is because the minimum of the power values from the DL path loss based open loop power control and the SL path loss based open loop power control is used, and both are used to perform transmit power control. Thus, if the path loss of the communication channel 115 (e.g., the downlink channel 115) is small, the power value from the open loop power control may be small, and the second terminal device 120 may be able to perform effective transmit power control using the path loss of the communication channel 115 rather than the path loss of the sidelink channel 125. In this case, measurement of the reference signal 135 may be required. In some embodiments, an indication to indicate whether the path loss of the communication channel 115 exceeds the second threshold is transmitted to the first terminal device 110 from the network device 130, e.g., via RRC signaling, or from the second terminal device 120, e.g., via a field in the SCI.

[0067] Alternatively or additionally, the measurement criterion may be that the priority of the sidelink data transmission performed via the sidelink channel 125 exceeds a configurable threshold (also referred to as a third threshold). In other words, if the priority of the sidelink data transmission exceeds the third threshold, the first terminal device 110 decides to measure the reference signal 135. Otherwise, if the priority of the sidelink data transmission is below the third threshold, the first terminal device 110 decides not to measure the reference signal 135.

[0068] Because the priority of the sidelink data transmission is low, the sidelink data transmission is not important, and thus the first terminal device 110 does not need to measure the reference signal 135 and therefore does not transmit the measurement report 155 to the second terminal device 120, avoiding any adverse impact on the communication between the first terminal device 110 or the second terminal device 120 and the network device 130. In some embodiments, an indication to indicate whether the priority of the sidelink data transmission exceeds the third threshold is transmitted from the network device 130, e.g., via RRC signaling, or from the second terminal device 120, e.g., via a field in the SCI, to the first terminal device 110.

[0069] In some embodiments, the first terminal device 110 has multiple ports for receiving the reference signal 135. For example, these antenna ports are numbered antenna port 0, antenna port 1, antenna port 2, etc. As specified by the 3GPP specifications, the antenna ports are defined so that the channel on which a code at an antenna port is transmitted can be inferred from the channel on which another code at the same antenna port is transmitted. Therefore, when measuring the reference signal 135, the first terminal device 110 measures the received power of the reference signal 135 received via one antenna port (e.g., antenna port 0) of the multiple antenna ports of the first terminal device 110. In this way, the measurement program for the reference signal 135 is simplified, and the load on the first terminal device 110 for measuring the reference signal is reduced. Alternatively, the first terminal device 110 can measure the average received power of the reference signal 135 received via the multiple antenna ports of the first terminal device 110. Therefore, the measurement result of the reference signal 135 becomes more accurate.

[0070] In some embodiments, reference signals (including reference signal 135) transmitted from second terminal device 120 to first terminal device 110 have various types. For example, these types include, but are not limited to, a PSSCH demodulation (DM)-reference signal (RS) type, a sidelink channel state information (CSI)-RS type, etc. Generally, first terminal device 110 can measure reference signals of any type. However, in some embodiments, first terminal device 110 is configured to measure reference signals of a predefined type, such as DM-RS or CSI-RS. Thus, when performing measurements, first terminal device 110 may only focus on one type of reference signal. For example, such configuration of first terminal device 110 is performed by higher layer configuration or SCI instruction.

[0071] In some other embodiments, when the first terminal device 110 performs measurement of reference signals from the second terminal device 120, there is a possibility that only one type of reference signal, for example, only DM-RS or CSI-RS, is present. In this case, the first terminal device 110 measures reference signals of a type that are present in the period in which the first terminal device 110 performs measurement. Alternatively, when the first terminal device 110 performs measurement, if reference signals having different types are transmitted from the second terminal device 120, the first terminal device 110 measures the reference signals having the different types. For example, if DM-RS and CSI-RS are present in the period in which the first terminal device 110 performs measurement, the first terminal device 110 measures the DM-RS and CSI-RS. In this way, the number of reference signals that the first terminal device 110 can measure is maximized.

[0072] In some embodiments, the first terminal device 110 measures the reference signal 135 at various timings. For example, when the reference signal 135 is associated with a sidelink data transmission over the sidelink channel 125, the first terminal device 110 measures the received power of the reference signal. In this example, the reference signal 135 is a DM-RS, and the first terminal device 110 measures the received power of the reference signal associated with each PSSCH transmission. In this manner, the first terminal device 110 can obtain measurement timing for measuring the maximum number of DM-RSs and more accurate measurement results.

[0073] Alternatively or additionally, if the first terminal device 110 receives an instruction from the second terminal device 120 that the received power of the reference signal 135 is to be measured, the first terminal device 110 measures the received power of the reference signal 135. For example, the instruction is transmitted via the SCI. Thus, the reference signal for measuring the received power and determining the path loss is selected by the second terminal device 120 and becomes the transmitter of the reference signal.

[0074] Alternatively or additionally, when the first terminal device 110 selects a reference signal 135 from multiple reference signals and measures the received power, the first terminal device 110 measures the received power of the reference signal 135. For example, if the measurable reference signals are DM-RS, the first terminal device 110 can decide to measure several reference signals associated with the selected PSSCH transmission. In this way, the first terminal device 110 can measure fewer reference signals, thereby saving processing resources and power for measurements. Optionally, the selection of the PSSCH transmission may be based on the radio distance between the first terminal device 110 and the second terminal device 120. If the radio distance is large, the second terminal device 120 may need to measure the reference signal 135, since it does not need to perform transmission power control using the path loss of the sidelink channel 125.

[0075] Alternatively or additionally, when the first terminal device 110 measures channel state information (CSI) of the sidelink channel 125 based on the reference signal 135, the first terminal device 110 measures the received power of the reference signal 135. For example, in this case, the reference signal 135 is a CSI-RS, and the measurement of the received power is synchronized with the CSI measurement. Thus, different types of measurements are performed in parallel based on the same reference signal, making full use of the CSI-RS and measurement timing.

[0076] 2, in order to avoid unnecessary measurement reports from the first terminal device 110 to the second terminal device 120, the first terminal device 110 determines whether to transmit a measurement report 155 to the second terminal device 120 at 217 based on the report criteria 145. In other words, the first terminal device 110 always does not transmit a measurement report to the second terminal device 120. Conversely, when it is necessary to transmit a measurement report 155 to the second terminal device 120, the first terminal device 110 transmits the measurement report 155 of the reference signal 135, thereby improving the effectiveness of the measurement report 155 of the second terminal device 120 and saving processing resources and other resources at the first terminal device 110 and the second terminal device 120 for transmitting or receiving unnecessary measurement reports.

[0077] In general, the reporting criteria 145 may be any suitable criteria that allows the first terminal device 110 to avoid unnecessary measurement reports. In some embodiments, the reporting criteria 145 may be similar to the measurement criteria described above and may be used by the first terminal device 110 to determine whether to measure the reference signal 135.

[0078] For example, the report criterion 145 may be that the second terminal device 120 performs transmission power control using the path loss of the sidelink channel 125. In other words, if the second terminal device 120 is configured to perform transmission power control using only the path loss of the sidelink channel 125, or to perform transmission power control using the path loss of the downlink channel 115 and the path loss of the sidelink channel 125, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120. Otherwise, if the second terminal device 120 is configured to perform transmission power control using only the path loss of the downlink channel 115, the measurement report 155 of the reference signal 135 in the sidelink channel 125 is invalid for the second terminal device 120, and therefore the first terminal device 110 does not need to transmit the measurement report 155 to the second terminal device 120.

[0079] Alternatively or additionally, the reporting criterion 145 may be that the estimated path loss (or radio distance) of the sidelink channel 125 is below a first threshold. In this case, if the estimated path loss is below the first threshold, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120. Otherwise, if the estimated path loss exceeds the first threshold, the first terminal device 110 may not transmit the measurement report 155 to the second terminal device 120. This is because, as described above, if the radio distance between the first terminal device 110 and the second terminal device 120 is large, the power value obtained by open-loop power control may become large. In this case, the second terminal device 120 may not need to control the transmission power using the path loss of the sidelink channel 125. In this case, the measurement report 155 of the reference signal 13 may not be necessary.

[0080] Alternatively or additionally, the report criterion 145 may be that the path loss (or wireless distance) of the communication channel 115 between the second terminal device 120 and the network device 130 exceeds a second threshold. In other words, if the path loss of the communication channel 115 exceeds the second threshold, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120. Otherwise, if the path loss of the communication channel 115 is below the second threshold, the first terminal device 110 may not transmit the measurement report 155 to the second terminal device 120. This is because, as described above, if the path loss of the communication channel 115 (e.g., the downlink channel 115) is small, the power value obtained by open-loop power control may be small. In this case, the second terminal device 120 may be able to control the transmission power using the path loss of the communication channel 115 rather than the path loss of the sidelink channel 125. In this case, the measurement report 155 of the reference signal 13 may not be necessary.

[0081] Alternatively or additionally, the reporting criterion 145 may be that the priority of the sidelink data transmission performed via the sidelink channel 125 exceeds a third threshold. In other words, if the priority of the sidelink data transmission exceeds the third threshold, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120. Otherwise, if the priority of the sidelink data transmission is below the third threshold, the first terminal device 110 may not transmit the measurement report 155 to the second terminal device 120. Because, as explained above, if the priority of the sidelink data transmission is low, the sidelink data transmission is not important, and therefore the first terminal device 110 may not transmit the measurement report 155 to the second terminal device 120, thereby avoiding any adverse effects on the communication between the first terminal device 110 or the second terminal device 120 and the network device 130.

[0082] The first terminal device 120 uses the measurement and reporting criteria 145, and the two criteria may be similar. In this case, the first terminal device 120 does not check the common criterion twice, but determines whether the common criterion is met only once. If the common criterion is met, the first terminal device 120 measures the reference signal 135 and then transmits the measurement report 155. Otherwise, if the common criterion is not met, the first terminal device 120 does not measure the reference signal 135 and does not transmit the measurement report 155. Also, in the described embodiment, a common first threshold, a common second threshold, and a common third threshold are configured to be used for the measurement and reporting criteria 145, but in some other embodiments, two different thresholds may be configured to be used for each of the two criteria.

[0083] 2 , if the first terminal device 110 determines to transmit the measurement report 155 at 217, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120 at 220, and the second terminal device 120 determines the path loss of the sidelink channel 125 based on the measurement report 155. Generally, the first terminal device 110 can use any available transmission resource to transmit the measurement report 155 at 220. For example, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120 on a predefined set of transmission resources of the PSSCH. The predefined set of transmission resources may be known to the first terminal device 110 and the second terminal device 120, so that the second terminal device 120 knows whether the transmission resource was used to transmit the measurement report.

[0084] Alternatively or additionally, the measurement report 155 may be transmitted on a selected set of transmission resources of the PSFCH, and the selected set may be indicated in an instruction transmitted from the first terminal device 110 to the second terminal device 120. In other words, the first terminal device 110 may select a selected set of transmission resources, and the first terminal device 110 may notify the second terminal device 120 whether the transmission resources were used to transmit the measurement report. Alternatively or additionally, the measurement report 155 may be transmitted in a medium access control (MAC) control element (CE) transmitted from the first terminal device 110 to the second terminal device 120. For example, a field in the MAC CE indicates the RSRP value to be reported. Alternatively or additionally, the measurement report 155 is transmitted from the first terminal device 110 to the second terminal device 120 on a set of transmission resources of the PSFCH.

[0085] In some embodiments, to avoid frequent measurement reports, the first terminal device 110 transmits the measurement report 155 if the difference between the value reported in the measurement report 155 and the previous value reported in the previous report exceeds a configurable threshold (also referred to as a fourth threshold). In other words, if the change in path loss of the sidelink channel 125 is sufficiently large, the first terminal device 110 transmits the measurement report 155 to the second terminal device 120. In this way, processing and other resources at the first terminal device 110 and the second terminal device 120 for transmitting or receiving measurement reports of the reference signal can be saved.

[0086] In some other embodiments, the first terminal device 110 periodically transmits multiple measurement reports, including the measurement report 155. Thus, the path loss of the sidelink channel 125 is periodically determined by the second terminal device 120, and the accuracy of the determined path loss may be periodically adjusted. In some embodiments, to report a received power value having a small absolute value, the first terminal device 110 subtracts a predefined value (e.g., −140 dBm) from the value to be reported, thus reducing the number of information bits for reporting the received power of the reference signal 135.

[0087] In some embodiments, the first terminal device 110, as a receiver of the reference signal 135, may determine the path loss of the sidelink channel 125 and perform transmit power control based on the path loss. For example, this may be the case when channel reciprocity of the sidelink channel 125 is assumed to be true. To this end, the first terminal device 110 receives information indicating the transmit power of the reference signal 135 from the second terminal device 120. The first terminal device 110 then performs transmit power control based on the difference between the transmit power of the reference signal 135 and the received power of the reference signal 135 measured by the first terminal device 110. In this way, the first terminal device 110 does not need to transmit a separate reference signal to the second terminal device 120 to determine the path loss of the sidelink channel 125.

[0088] In some embodiments, before using the difference to control the transmit power, the first terminal device 110 performs Layer 3 filtering on the difference. For example, Layer 3 filtering may be performed based on equation (1) specified in the 3GPP specifications. In some embodiments, the transmit power control performed by the first terminal device 110 can be transmitted to the second terminal device 120 via a measurement report 155 or any other sidelink data. In some embodiments, the transmit power control at the first terminal device 110 can be performed if the first terminal device 110 is configured to use the path loss of the sidelink channel 125 to control the transmit power.

[0089] As described above, in NR sidelink communication, the transmission power of a reference signal may change for each time slot by controlling the transmission power of a transmitting terminal device. Furthermore, when a receiving terminal device uses each measurement report to report the reception power of multiple reference signals, these measurement reports have a time domain order that differs from the transmission time domain order of the reference signals. Furthermore, the receiving terminal device may miss some reference signals among the multiple reference signals transmitted by the transmitting terminal device.

[0090] Therefore, in traditional solutions, when a transmitting terminal device of multiple reference signals receives measurement reports from receiving terminal devices of multiple reference signals, the transmitting terminal device may not know the transmit power of the reference signals associated with the measurement reports. Therefore, the transmitting terminal device may not be able to determine the path loss of the sidelink channel. Some embodiments of the present disclosure provide a solution to this problem. This method is called a time-window averaging method, which will be described in detail below with reference to Figures 3, 4A, 4B, 5A, and 5B.

[0091] 3 illustrates another exemplary communication process 300 between a first terminal device 110 and a second terminal device 120 in accordance with some embodiments of the present disclosure. Communication process 300 may be considered another embodiment of communication process 200 of FIG. 2. For purposes of discussion, communication process 300 will be described with reference to FIGS. 1, 4A, and 4B, although communication process 300 here also applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0092] 4A illustrates an exemplary scenario according to some embodiments of the present disclosure, in which a first terminal device 110 transmits a measurement report for each of multiple reference signals to a second terminal device 120. FIG. 4B illustrates an exemplary scenario according to some embodiments of the present disclosure, in which the first terminal device 110 reports the average received power of multiple reference signals by transmitting a single measurement report to a second terminal device 120.

[0093] As shown in Figures 3 and 4A, during a time window 405, the second terminal device 120 transmits 210 multiple reference signals 410, 135, and 420 to the first terminal device 110 via the sidelink channel 125. In the exemplary scenario of Figure 4A, the time window 405 is defined with the second terminal device 120 as the transmitter of the multiple reference signals 410, 135, and 420. The length and location of the time window 405 in the time domain may be configured, for example, by higher layers. Note that the number of reference signals and measurement reports in Figures 4A and 4B are not intended to be limiting and are merely for illustrative purposes. In other embodiments, the time window 405 includes any suitable number of reference signals and any suitable number of measurement reports.

[0094] In some embodiments, when multiple reference signals 410, 135, and 420 are associated with a data transmission 440 in the sidelink channel 125, a time window 405 is defined for the time of the data transmission 440. For example, if the data transmission 440 is to occur in a timeslot with sequence number (or index) N, then a start point A of the time window 405 is defined at the timeslot with sequence number (Na) and an end point B of the time window 405 is defined at the timeslot with sequence number (Nb), where "N", "a", and "b" are integers whose values are configured by higher layers.

[0095] After transmitting the plurality of reference signals 410, 135, and 420 to the first terminal device 110, the second terminal device 120 determines in 315 the average received power of the plurality of reference signals 410, 135, and 420 measured by the first terminal device 110 during the time window 405. There are various ways for the second terminal device 120 to determine the average received power in 315. As a first option, the first terminal device 110 reports the received power of each reference signal among the reference signals 410, 135, and 420 to the second terminal device 120, and the second terminal device 120 calculates the average received power. In this way, the complexity of the first terminal device 110 is reduced. Alternatively, as a second option, the first terminal device 110 calculates the average received power and reports it to the second terminal device 120. Thus, the number of measurement reports transmitted from the first terminal device 110 to the second terminal device 120 is reduced.

[0096] Therefore, the specific manner in which second terminal device 120 determines average received power in 315 may depend on how first terminal device 110 reports measurement results of multiple reference signals 410, 135, and 420 to second terminal device 120. The first option will be described in detail below with reference to Figures 4A and 5A, and the second option will be described in detail with reference to Figures 4B and 5B.

[0097] 5A illustrates another exemplary communication process 500 between a first terminal device 110 and a second terminal device 120 in accordance with some embodiments of the present disclosure. Communication process 500 may be considered an embodiment of communication process 300 of FIG. 3. For purposes of discussion, communication process 500 will be described with reference to FIGS. 1 and 4A, although communication process 500 here also applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0098] 4A and 5A, in a first option, the first terminal device 110 generates each measurement report for a plurality of reference signals 410, 135, and 420 in 215, and then transmits the measurement report to the second terminal device 120 in 220. In other words, for each reference signal among the plurality of reference signals 410, 135, and 420, the first terminal device 110 generates a measurement report in 215 so as to include information indicating the received power of the reference signal. For example, the first terminal device 110 generates in 215 a measurement report 415 for reporting the received power of the reference signal 410, a measurement report 155 for reporting the received power of the reference signal 135, and a measurement report 425 for reporting the received power of the reference signal 420. The first terminal device 110 then transmits the measurement reports 415, 155, and 425 to the second terminal device 120 in 220.

[0099] 4A, the time domain order of measurement reports 415, 425, and 155 is different from the time domain order of the transmission of reference signals 410, 135, and 420. However, embodiments of the present disclosure equally apply to other scenarios in which measurement reports have the same order as the reference signals in the time domain, or in which one or more reference signals are not measured by the receiving device, for example, the first terminal device 110 may not be able to measure reference signal 420 and does not transmit measurement report 425, but only transmits measurement reports 415 and 155.

[0100] If the first terminal device 110 transmits each measurement report 415, 425, and 155 at 220, the second terminal device 120 can receive multiple measurement reports 415, 425, and 155 from the first terminal device 110 in the time window 405 at 220. As described, the first terminal device 110 uses multiple measurement reports 415, 425, and 155 to report multiple received power amplitudes of multiple reference signals 410, 135, and 420, respectively. Thus, the second terminal device 120 obtains the average received power at 510 by averaging the multiple received power amplitudes reported by the first terminal device 110.

[0101] As described above, first terminal device 110 transmits multiple measurement reports 410, 135, and 420 using various resources. In some embodiments, first terminal device 110 transmits multiple measurement reports 410, 135, and 420 from first terminal device 110 to second terminal device 120 on a predefined set of transmission resources of the PSSCH. For example, multiple measurement reports 410, 135, and 420 are multiplexed on predefined PSSCH resources. Alternatively or additionally, first terminal device 110 may transmit multiple measurement reports 410, 135, and 420 on a selected set of transmission resources of the PSSCH, and an indication sent from first terminal device 110 to second terminal device 120 may indicate the selected set. For example, multiple measurement reports 410, 135, and 420 are transmitted on resources allocated similarly to the PSSCH, and an indication in the SCI indicates the presence of a measurement report.

[0102] Alternatively or additionally, first terminal device 110 transmits multiple measurement reports 410, 135, and 420 from first terminal device 110 to second terminal device 120 in MAC CE. For example, a field in MAC CE indicates the RSRP value to be reported. Alternatively or additionally, first terminal device 110 transmits multiple measurement reports 410, 135, and 420 from first terminal device 110 to second terminal device 120 in a set of transmission resources of the PSFCH. Thus, depending on the transmission channel or message transmitting multiple measurement reports 410, 135, and 420 at 220, second terminal device 120 can receive multiple measurement reports 415, 425, and 155 at 220 from one of these transmission channels or messages.

[0103] 5B illustrates another exemplary communication process 550 between first terminal device 110 and second terminal device 120 in accordance with some embodiments of the present disclosure. Communication process 550 may be considered another embodiment of communication process 300 of FIG. 3. For purposes of discussion, communication process 550 will be described with reference to FIG. 4B, where communication process 550 equally applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0104] 4A, as shown in FIG. 4B, unlike the scenario of FIG. 4A, a time window 405 can be defined in the first terminal device 110 and the second terminal device 120, and a single measurement report 155 of multiple reference signals 410, 135, and 420 is generated and transmitted to the second terminal device 120. Referring to FIG. 5B, when the measurement report 155 is generated in 215, the first terminal device 110 can determine the time window 405 for generating the measurement report 155. Then, the first terminal device 110 can obtain the average received power of the multiple reference signals 410, 135, and 420 measured by the first terminal device 110 in the time window 405. When the average received power is obtained, the first terminal device 110 generates the measurement report 155 to include information indicating the average received power.

[0105] The first terminal device 110 then transmits the measurement report 155 to the second terminal device 120 at 220. Thus, having determined the average received power of the multiple reference signals 410, 135, and 420 at 315, the second terminal device 120 receives the measurement report 155 from the first terminal device 110 at 220 during the time window 405 (e.g., at or before endpoint B), and then obtains the average received power of the reference signals 410, 135, and 420 from the measurement report 155 at 560.

[0106] 4A and 5A, the first terminal device 110 transmits the measurement report 135 using various resources. For example, the first terminal device 110 transmits the measurement report 135 from the first terminal device 110 to the second terminal device 120 on a predefined set of transmission resources of the PSSCH. Alternatively or additionally, the first terminal device 110 transmits the measurement report 135 on a selected set of transmission resources of the PSSCH, with an indication sent from the first terminal device 110 to the second terminal device 120 indicating the selected set. For example, the measurement report 135 is transmitted on resources allocated similarly to the PSSCH, with an indication in the SCI indicating the presence of the measurement report.

[0107] Alternatively or additionally, in MAC CE, first terminal device 110 transmits measurement report 135 from first terminal device 110 to second terminal device 120. For example, a field in MAC CE indicates the RSRP value to be reported. Alternatively or additionally, in a set of transmission resources of the PSFCH, first terminal device 110 transmits measurement report 135 from first terminal device 110 to second terminal device 120. Thus, depending on the transmission channel or message transmitting measurement report 135 in 220, second terminal device 120 receives measurement report 135 from one of these transmission channels or messages in 220.

[0108] Referring back to FIG. 3 , after determining the average received power of the plurality of reference signals 410, 135, and 420 in 315, the second terminal device 120 determines the path loss of the sidelink channel 125 in 320 based on the difference between the average received power and the average transmit power of the plurality of reference signals 410, 135, and 420. In some embodiments, the average transmit power and the average received power are already average values associated with the plurality of reference signals or measurements within the time window 405. Therefore, as a simple option, the second terminal device 120 can directly determine the difference between the average received power and the average transmit power as the path loss. Alternatively, in a more accurate manner, the second terminal device 120 can perform Layer 3 filtering on the difference to obtain the path loss. For example, Layer 3 filtering may be performed based on equation (1) specified in the 3GPP specifications.

[0109] As shown, in traditional solutions, due to various reasons, when a transmitting terminal device of multiple reference signals receives a measurement report from a receiving terminal device of multiple reference signals, the transmitting terminal device may not know the reference signal associated with the measurement report. Some embodiments of the present disclosure solve this technical problem. According to these embodiments of the present disclosure, when a transmitting terminal device of multiple reference signals receives a measurement report, the transmitting terminal device determines the reference signal associated with the measurement report based on an implicit or explicit mapping between the measurement report and the reference signal. These embodiments of the present disclosure will be described in detail below with reference to Figures 6 to 9.

[0110] 6 illustrates another exemplary communication process 600 between a first terminal device 110 and a second terminal device 120 in accordance with some embodiments of the present disclosure. Communication process 600 may be considered another embodiment of communication process 200 of FIG. 2. For purposes of discussion, communication process 600 will be described with reference to FIG. 1, although communication process 600 here also applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0111] As shown in FIG. 6 , the first terminal device 110 reports the received power of the reference signal 135 measured by the first terminal device 110 by transmitting a measurement report 155 at 220. In some embodiments, when the measurement report 155 is received, the transmission manner of the measurement report 155 implicitly indicates an association between the measurement report 155 and the reference signal 135, so as to inform the second terminal device 120 that the measurement report 155 is used for the reference signal 135. Thus, from the perspective of a receiving device of the measurement report 155, the second terminal device 120 receives the measurement report 155 from the first terminal device 110 at 220. Then, based on the transmission manner of the measurement report 155, i.e., the reception manner of the measurement report 155, the second terminal device 120 can determine that the measurement report 155 is associated with the reference signal 135.

[0112] As an example of such implicit indication, first terminal device 110 may use a correspondence relationship between a reference signal, a PSSCH, and a PSFCH to implicitly indicate an association between a reference signal and its measurement report. Specifically, in sidelink communication, there is a one-to-one mapping between a PSSCH and its associated PSFCH. Thus, if reference signal 135 is associated with a PSSCH from second terminal device 120 to first terminal device 110, first terminal device 110 transmits measurement report 155 on the PSFCH from first terminal device 110 to second terminal device 120 associated with the PSSCH.

[0113] That is, the relationship between the PSSCH and its associated PSFCH implicitly indicates the relationship between the measurement report 155 and the reference signal 135. Therefore, based on the relationship between the PSSCH of the reference signal 135 and the PSFCH transmitting the measurement report 155, the second terminal device 120 as a receiving device of the measurement report 155 can determine that the measurement report 155 is used for the reference signal 135. Such implicit indication will be described in detail below with reference to FIG. 7.

[0114] 7 illustrates an exemplary resource distribution for transmitting reference signals and associated measurement reports in accordance with some embodiments of the present disclosure, where the measurement reports are transmitted on a PSFCH associated with a PSSCH associated with the reference signal. In FIG. 7, the horizontal axis represents the time domain, the vertical axis represents the frequency domain, and each block represents a time-frequency resource, e.g., a time slot and a subchannel resource.

[0115] As shown in the drawing, second terminal device 120 transmits a first reference signal (e.g., reference signal 135) in a first PSSCH resource 710 and transmits a second reference signal in a second PSSCH resource 720. Assume that first PSSCH resource 710 is associated with a first PSFCH resource 715 and that second PSSCH resource 720 is associated with a second PSFCH resource 725. Thus, first terminal device 110 transmits a first measurement report (e.g., measurement report 155) for the first reference signal in first PSFCH resource 715 and transmits a second measurement report for the second reference signal in second PSFCH resource 725. In this way, when second terminal device 120 receives the first measurement report in first PSFCH resource 715, it can determine that the first measurement report is used for the first reference signal transmitted in first PSSCH resource 710. Similarly, if a second measurement report is received in the second PSFCH resource 725, the second terminal device 120 can determine that the second measurement report is used for the second reference signal transmitted in the second PSSCH resource 720.

[0116] In some embodiments, to transmit measurement report 155 over the PSFCH, first terminal device 110 performs a cyclic shift on a bit sequence to be transmitted over the PSFCH based on a value to be reported in measurement report 155 to obtain a shifted bit sequence. First terminal device 110 then transmits the shifted bit sequence over the PSFCH to second terminal device 120. Thus, second terminal device 120 decodes the PSFCH to obtain the shifted bit sequence, and then determines a value to be reported in measurement report 155 based on the shifted bit sequence. In this way, it is not necessary to add more information bits than are intended to be transmitted over the PSFCH to indicate a value to be reported in measurement report 155.

[0117] As another example of implicit instruction, the second terminal device 120 and the first terminal device 110 each transmit a reference signal and a measurement report using two corresponding ordered sets of time-frequency resources. Specifically, the first ordered set and the second ordered set have the same number of time-frequency resources, and each time-frequency resource in the first ordered set is associated with each time-frequency resource in the second ordered set. Therefore, the time-frequency resources in the first ordered set and the time-frequency resources in the second ordered set have a one-to-one mapping. Such implicit instruction will be described in detail below with reference to FIG. 8.

[0118] 8 illustrates another exemplary resource distribution for transmitting reference signals and associated measurement reports according to some embodiments of the present disclosure, where two ordered sets of time-frequency resources transmit the reference signals and associated measurement reports. In FIG. 8, the horizontal axis represents the time domain, the vertical axis represents the frequency domain, and each block represents a time-frequency resource.

[0119] 8, a first ordered set of time-frequency resources includes resource 810, resource 812, resource 814, resource 816, resource 818, resource 820, resource 822, resource 824, resource 826, resource 828, resource 830, and resource 832. A second ordered set of time-frequency resources includes resource 840, resource 842, resource 844, resource 846, resource 850, resource 852, resource 854, resource 856, resource 858, resource 860, and resource 862.

[0120] Here, the number of resources in the first ordered set and the number of resources in the second ordered set in FIG. 8 are not intended to be limiting and are merely for illustrative purposes. In other embodiments, the first ordered set includes any suitable number of time-frequency resources, and the second ordered set includes any suitable number of time-frequency resources. Also, although the size of each of the time-frequency resources in the second ordered set is illustrated as a fraction of the size of each of the time-frequency resources in the first ordered set, the size of each resource in the first ordered set and the size of each resource in the second ordered set may have any suitable relationship. Furthermore, the positional relationship between the first ordered set and the second ordered set is not limited to the illustrated positional relationship and may be any suitable positional relationship.

[0121] In the example of FIG. 8, resource 810 corresponds to resource 840, resource 812 corresponds to resource 842, resource 814 corresponds to resource 844, resource 816 corresponds to resource 846, resource 818 corresponds to resource 848, resource 820 corresponds to resource 850, resource 822 corresponds to resource 852, resource 824 corresponds to resource 854, resource 826 corresponds to resource 856, resource 828 corresponds to resource 858, resource 830 corresponds to resource 860, and resource 832 corresponds to resource 862.

[0122] In this case, when transmitting measurement report 155 at 220, if first terminal device 110 determines that reference signal 135 is to be transmitted on a first time frequency resource (e.g., resource 820) in a first ordered set of time frequency resources, first terminal device 110 can determine a sequence number of the first time frequency resource in the first ordered set, for example, 6. Then, based on the sequence number (e.g., 6), first terminal device 110 selects a second time frequency resource (e.g., resource 850) from a second ordered set of time frequency resources. Then, first terminal device 110 transmits measurement report 155 on second time frequency resource 850.

[0123] In the example of Figure 8, it is assumed that the first ordered set and the second ordered set are derived from a resource pool. A measurement report is configured to be transmitted in an end time slot of every N time slots, where N is equal to 5 in this example. However, the measurement report may also be configured to be transmitted in another time slot (e.g., the start time slot). In the example of Figure 8, the mapping rule for the order of the first ordered set is as follows: first consider the time domain, then consider the frequency domain. However, in other embodiments, the order may be reversed: first consider the frequency domain, then consider the time domain. More generally, the resources in the first ordered set may have any order.

[0124] As an alternative solution to the above implicit instruction, the first terminal device 110 explicitly indicates the association between the measurement report 155 and the reference signal 135 in the measurement report 155. For example, the first terminal device 110 notifies the second terminal device 120 of the time point when the first terminal device 110 measures the reference signal 135 through the measurement report 155, thereby informing the second terminal device 120 that when the measurement report 155 is received, the time point indicated in the measurement report 155 will be used for the reference signal 135 to be transmitted. Such explicit instruction will be described in detail below with reference to FIG. 9.

[0125] 9 illustrates another exemplary resource distribution for transmitting reference signals and associated measurement reports according to some embodiments of the present disclosure, where the measurement reports include time information of the associated reference signals. In FIG. 9, the horizontal axis represents the time domain, the vertical axis represents the frequency domain, and each block represents a time-frequency resource. As shown in FIG. 9, second terminal device 120 transmits a first reference signal (e.g., reference signal 135) in resource 910 and a second reference signal in resource 920. First terminal device 110 transmits a first measurement report (e.g., measurement report 155) of the first reference signal in resource 915 and a second measurement report of the second reference signal in resource 925. In some embodiments, the resource pool of first device 110 and the resource pool of second device 120 may be different.

[0126] In this case, when generating measurement report 15 at 215, first terminal device 110 determines the time point at which first terminal device 110 measures reference signal 135, for example, the time point of resource 910. Then, first terminal device 110 generates measurement report 155 at 215 to include information indicating the time point of resource 910. In a similar manner, first terminal device 110 generates second measurement report 155 to include information indicating the time point of indicated resource 920. In some embodiments, the information includes the index of the time slot of resource 910. For example, the time slot index range may be 0 to 10239.

[0127] When generating the measurement report 155 at 215, instead of indicating the time point of the reference signal 135, the first terminal device 110 determines a first time point (e.g., the time point of resource 910) at which the first terminal device 110 measures the reference signal 135. The first terminal device 110 also determines a second time point (e.g., the time point of resource 915) at which the first terminal device 110 transmits the measurement report. Then, the first terminal device 110 generates the measurement report 155 to include information indicating the time difference between the first time point and the second time point.

[0128] In a similar manner, the first terminal device 110 generates the second measurement report to include information indicating the time difference between the first time point of the resource 920 and the second time point of the resource 925. In some embodiments, the time difference is indicated by a time slot offset between the time slot in which the reference signal 135 is transmitted and the time slot in which the measurement report is transmitted. Alternatively, the time difference is indicated by an absolute time offset (in milliseconds or seconds) between the time point in which the measurement report 155 is transmitted and the time point in which the reference signal 135 is transmitted.

[0129] In some embodiments, when transmitting measurement report 155 in MAC CE, a field in MAC CE may indicate time information of the associated reference signal. For example, the time information may be a time slot index of a resource for transmitting reference signal 135, or a time slot offset between the time slot for transmitting reference signal 135 and the time slot for transmitting measurement report. Also, the field in MAC CE may indicate a value to be reported in measurement report 155.

[0130] 6, after receiving 220 measurement report 155 from the first terminal device 110, the second terminal device 120 determines the transmission power of the reference signal 135 in 610. The manner in which the second terminal device 120 determines the transmission power in 610 depends on the manner in which the first terminal device 110 transmits the measurement report 155 (in the case of an implicit instruction) or the content of the measurement report 155 (in the case of an explicit instruction).

[0131] For example, in the embodiment described with reference to FIG. 7, if second terminal device 120 receives measurement report 155 on the PSFCH (e.g., transmits on resource 715 in FIG. 7), second terminal device 120 can determine the PSSCH associated with the PSFCH (e.g., transmits on resource 710 in FIG. 7). Then, for example, second terminal device 120 can determine the transmit power of reference signal 135 associated with the PSSCH because reference signal 135 is transmitted on resource 710.

[0132] 8, if the second terminal device 120 receives the measurement report 155 on a second time frequency resource (e.g., resource 850) in the second ordered set of time frequency resources, the second terminal device 120 can determine the sequence number (e.g., 6) of the second time frequency resource in the second ordered set. Then, based on the sequence number (e.g., 6), the second terminal device 120 can determine the first time frequency resource (e.g., resource 820) in the second ordered set of time frequency resources. The second terminal device 120 can then determine the transmit power of the reference signal 135 since it is transmitted on the first time frequency resource (e.g., resource 820).

[0133] 9, the second terminal device 120 can determine, in the measurement report 155, a first time point (e.g., a time slot number of the resource 910) at which the second terminal device 120 transmits the reference signal 135. Then, the second terminal device 120 can obtain the transmission power of the reference signal 135 to be transmitted at the first time point (e.g., the time slot number of the resource 910).

[0134] Alternatively, the second terminal device 120 can determine a second time point (e.g., a timeslot number of the resource 915) at which the second terminal device 120 receives the measurement report 135. The second terminal device 120 can then determine a time difference (e.g., 4) between the first time point (e.g., a timeslot number of the resource 910) and the second time point (e.g., a timeslot number of the resource 915) in the measurement report 155. Then, based on the second time point (e.g., a timeslot number of the resource 915) and the time difference (e.g., 4), the second terminal device 120 can determine the first time point (e.g., a timeslot number of the resource 910). The second terminal device 120 can then obtain the transmission power of the reference signal 135 to be transmitted at the first time point (e.g., a timeslot number of the resource 910).

[0135] 6, based on the received power of the reference signal 135 reported in the measurement report 55 and the determined transmit power of the reference signal 135, the second terminal device 120 determines 620 the path loss of the sidelink channel 125. In some embodiments, the second terminal device 120 determines the difference between the received power and the transmit power and then performs Layer 3 filtering on the difference to obtain the path loss, for example, according to equation (1) specified in the 3GPP specifications.

[0136] Alternatively, the second terminal device 120 can first determine the previous transmit power of the previous reference signal transmitted from the second terminal device 120 to the first terminal device 110. Then, the second terminal device 120 adjusts the received power using the transmit power and the previous transmit power to obtain the adjusted received power. In general, the second terminal device 120 can adjust the received power using any appropriate adjustment method. For example, the received power may be adjusted based on the following equation (2):

number

[0137] After adjusting the received power, the second terminal device 120 performs layer 3 filtering on the adjusted received power to obtain filtered received power. For example, this operation can be expressed by the following equation (3).

number

[0138] After obtaining the filtered received power, the second terminal device 120 determines the path loss based on the difference between the transmitted power and the filtered received power. i -RSRP_filtered(i) represents the path loss.

[0139] As described above, before the first terminal device 110 uses the received power of the reference signal 135 measured to determine the path loss of the sidelink channel 125, the second terminal device 120 performs Layer 3 filtering on the received power of the reference signal 135 to obtain the filtered received power, which is actually used by the second terminal device 120 to determine the path loss of the sidelink channel 125. In some embodiments, the Layer 3 filtering is performed by the first terminal device 110 as the receiving terminal device of the reference signal 135, rather than by the second terminal device 120 as the transmitting terminal device of the reference signal 135. In this way, the complexity of the reference signal transmitting device is reduced. These embodiments are described in detail below with reference to FIG. 10.

[0140] 10 illustrates another exemplary communication process 1000 between a first terminal device 110 and a second terminal device 120 in accordance with some embodiments of the present disclosure. Communication process 1000 may be considered another embodiment of communication process 200 of FIG. 2. For purposes of discussion, communication process 1000 will be described with reference to FIG. 1, although communication process 1000 here also applies to other communication scenarios of communication between two terminal devices over a sidelink channel.

[0141] 10 , in order to enable the first terminal device 110 to perform Layer 3 filtering, the second terminal device 120 transmits information to the first terminal device 110 at 1010, so that the first terminal device 110 performs Layer 3 filtering on the received power of the reference signal 135 measured by the first terminal device 110. Here, the information may be any information that enables the first terminal device 110 to perform Layer 3 filtering, and the content of the information depends on the method of performing Layer 3 filtering by the first terminal device 110. For example, the information includes transmission power information of the reference signal 135.

[0142] Specifically, as an example, the information includes the transmit power of the reference signal 135 shared between the first terminal device 110 and the second terminal device 120, and the reference transmit power of the reference signal 135. Thus, the first terminal device 110 uses the transmit power and the reference transmit power to perform Layer 3 filtering on the received power measured by the reference signal 135. In some embodiments, the second terminal device 120 notifies the first terminal device 110 of the reference transmit power, for example, via higher layer signaling. In some other embodiments, the network device 130 determines the reference transmit power and notifies the first terminal device 110 and the second terminal device 120 of the reference transmit power, for example, via higher layer signaling. Information including the reference transmit power is transmitted via an SCI or higher layer signaling used for timing to measure the reference signal 135.

[0143] Alternatively, as another example, the information includes the transmit power of the reference signal 135 and the previous transmit power of the previous reference signal transmitted from the second terminal device 110 to the first terminal device 120. In this case, the first terminal device 110 uses the transmit power and the previous transmit power to perform Layer 3 filtering on the received power measured by the reference signal 135. The information including the previous transmit power is transmitted via a physical sidelink control channel (PSCCH) / PSSCH or higher layer signaling used for timing to measure the reference signal 135.

[0144] After receiving information from the second terminal device 120 at 1010, the first terminal device 110 generates a measurement report 155 at 215 based on the information to include the filtered received power of the reference signal 135. The specific manner in which the first terminal device 110 performs Layer 3 filtering on the received power of the reference signal 135 depends on the specific content of the information. In some embodiments, the first terminal device 110 first obtains the adjusted received power by adjusting the received power of the reference signal 135 measured by the first terminal device 110. Such adjustment of the received power is also referred to as normalization, and therefore the adjusted received power is also referred to as normalized received power.

[0145] The adjustment of the received power may be different for different contents of the information received from the second terminal device 120. If the information includes the reference transmission power and the transmission power, the first terminal device 110 adjusts the received power using the transmission power and the reference transmission power. For example, the adjusted received power of the reference signal 135 is obtained by the following equation (4):

number

[0146] Here, the above equation (4) is not limiting and merely exemplifies the adjustment of the received power of the reference signal 135. In some other embodiments, the first terminal device 110 may perform the adjustment using any other suitable mathematical operation or non-mathematical method. Also, as shown above, alternatively, the reference transmit power is notified to the first terminal device 110 by the network device 130, rather than by the second terminal device 120. Regardless of the provider of the reference transmit power information, the first terminal device 110 can determine the reference transmit power of the reference signal 135 shared between the first terminal device 110 and the second terminal device 120.

[0147] Alternatively, if the information received by the first terminal device 110 from the second terminal device 120 includes the transmission power and the previous transmission power, the first terminal device 110 can adjust the reception power using the transmission power and the previous transmission power. For example, the adjusted reception power of the reference signal 135 is obtained by the following equation (5):

number

[0148] After obtaining the adjusted received power of the reference signal 135, the first terminal device 110 performs Layer 3 filtering on the adjusted received power to obtain filtered received power. The first terminal device 110 performs Layer 3 filtering in various manners. In some embodiments, the Layer 3 filtering is performed based on the following equation (6):

number

[0149] When the filtered received power of the reference signal 135 is acquired, the first terminal apparatus 110 generates a measurement report 155 at 215 so as to include information indicating the filtered received power. Then, the first terminal apparatus 110 transmits the measurement report 155 including the filtered received power of the reference signal 135 to the second terminal apparatus 120. Therefore, from the receiving side, the second terminal apparatus 120 receives the measurement report 155 from the first terminal apparatus 110 at 220.

[0150] When receiving the measurement report 155 indicating the filtered received power, the second terminal device 120 determines the path loss of the sidelink channel 125 at 1020 based on the filtered received power of the reference signal 135 and the information transmitted from the second terminal device 120 to the first terminal device 110. For example, if the information includes the reference transmit power and the transmit power, the second terminal device 120 can determine the difference between the reference transmit power and the filtered received power as the path loss. Alternatively, if the information includes the transmit power and the previous transmit power, the second terminal device 120 determines the difference between the transmit power and the filtered received power as the path loss.

[0151] 11 illustrates a flowchart of an exemplary method 1100 according to some embodiments of the present disclosure. In some embodiments, method 1100 is performed in a terminal device, for example, first terminal device 110 of FIG. 1. Additionally or alternatively, method 1100 may be performed in a second terminal device or other terminal device not shown in FIG. 1. For purposes of discussion, and without loss of generality, first terminal device 110 will be described as performing method 1100 with reference to FIG. 1.

[0152] In block 1110, the first terminal device 110 generates a measurement report by measuring a reference signal transmitted via a sidelink channel from the second terminal device 120. In block 1120, the first terminal device 110 determines, based on a reporting criterion, whether to transmit the measurement report to the second terminal device 120. In block 1130, in response to determining to transmit the measurement report, the first terminal device 110 transmits the measurement report to the second terminal device 120, and the second terminal device 120 determines a path loss of the sidelink channel based on the measurement report.

[0153] In some embodiments, the reporting criteria include at least one of: the second terminal device 120 uses the path loss of the sidelink channel to perform transmission power control; the estimated path loss of the sidelink channel is below a first threshold; the path loss of the communication channel between the second terminal device 120 and the network device 130 communicating with the second terminal device 120 exceeds a second threshold; and the priority of the sidelink data transmission to be performed on the sidelink channel exceeds a third threshold.

[0154] In some embodiments, generating the measurement report includes determining whether to measure the reference signal based on a measurement criterion, and generating the measurement report in response to determining to measure the reference signal.

[0155] In some embodiments, the reporting criteria include at least one of: the second terminal device 120 uses the path loss of the sidelink channel to perform transmission power control; the estimated path loss of the sidelink channel is below a first threshold; the path loss of the communication channel between the second terminal device 120 and the network device 130 communicating with the second terminal device 120 exceeds a second threshold; and the priority of the sidelink data transmission to be performed on the sidelink channel exceeds a third threshold.

[0156] In some embodiments, measuring the reference signal includes at least one of measuring the received power of the reference signal received via one antenna port of the first terminal device 110 and measuring the average received power of the reference signal received via the first terminal device 110's multiple antenna ports.

[0157] In some embodiments, measuring the reference signal includes at least one of: measuring the received power of the reference signal in response to the reference signal being associated with a sidelink data transmission via a sidelink channel; measuring the received power of the reference signal in response to receiving an indication from the second terminal device 120 that the received power of the reference signal is to be measured; measuring the received power of the reference signal in response to measuring the received power by selecting a reference signal from a plurality of reference signals; and measuring the received power of the reference signal in response to measuring channel state information of the sidelink channel based on the reference signal.

[0158] In some embodiments, generating the measurement report includes generating the measurement report to include information indicative of the received power of the reference signal.

[0159] In some embodiments, generating the measurement report includes determining a time window for generating the measurement report, obtaining an average received power of a plurality of reference signals, the plurality of reference signals including reference signals measured by the first terminal device 110 in the time window, and generating the measurement report to include information indicating the average received power.

[0160] In some embodiments, the measurement report is transmitted on at least one of a predefined set of transmission resources for the PSSCH from the first terminal device 110 to the second terminal device 120, a selected set of transmission resources for the PSSCH, the selected set being indicated in an instruction transmitted from the first terminal device 110 to the second terminal device 120, a MAC CE transmitted from the first terminal device 110 to the second terminal device 120, and a set of transmission resources for the PSFCH from the first terminal device 110 to the second terminal device 120.

[0161] In some embodiments, transmitting the measurement report includes transmitting the measurement report on a PSFCH from the first terminal device 110 to the second terminal device 120 that is associated with the PSSCH in response to the reference signal being associated with the PSSCH from the second terminal device 120 to the first terminal device 110.

[0162] In some embodiments, transmitting the measurement report on the PSFCH includes performing a cyclic shift on a bit sequence to be transmitted on the PSFCH based on a value to be reported in the measurement report to obtain a shifted bit sequence, and transmitting the shifted bit sequence to the second terminal device 120 on the PSFCH.

[0163] In some embodiments, transmitting the measurement report includes: determining a sequence number of a first time-frequency resource in the first ordered set of time-frequency resources in response to transmitting a reference signal in the first time-frequency resource in the first ordered set of time-frequency resources; selecting a second time-frequency resource from a second ordered set of time-frequency resources based on the sequence number, wherein each time-frequency resource in the second ordered set is associated with a respective time-frequency resource in the first ordered set; and transmitting the measurement report in the second time-frequency resource.

[0164] In some embodiments, generating the measurement report includes determining a first time point at which the first terminal device 110 measures the reference signal, and generating the measurement report to include information indicating the first time point.

[0165] In some embodiments, generating the measurement report includes determining a first time point at which the first terminal device 110 measures the reference signal, determining a second time point at which the first terminal device 110 transmits the measurement report, and generating the measurement report to include information indicating a time difference between the first time point and the second time point.

[0166] In some embodiments, generating the measurement report includes adjusting the received power of the reference signal measured by the first terminal device 110 to obtain an adjusted received power, performing Layer 3 filtering on the adjusted received power to obtain a filtered received power, and generating the measurement report to include information indicating the filtered received power.

[0167] In some embodiments, adjusting the received power includes determining a reference transmission power of a reference signal shared between the first terminal device 110 and the second terminal device 120, receiving information indicating the transmission power of the reference signal from the second terminal device 120, and adjusting the received power using the transmission power and the reference transmission power.

[0168] In some embodiments, adjusting the received power includes receiving information from the second terminal device 120 indicating a transmit power of the reference signal and a previous transmit power of a previous reference signal, the previous reference signal being transmitted from the second terminal device 120 to the first terminal device 110, and adjusting the received power using the transmit power and the previous transmit power.

[0169] In some embodiments, the method 1100 further includes receiving information indicating the transmission power of the reference signal from the second terminal device 120, and performing control of the transmission power based on a difference between the transmission power and the received power of the reference signal measured by the first terminal device 110.

[0170] In some embodiments, transmitting the measurement report includes transmitting the measurement report in response to a difference between a value reported in the measurement report and a previous value reported in a previous report exceeding a fourth threshold, or periodically transmitting a plurality of measurement reports including the measurement report.

[0171] 12 illustrates a flowchart of another exemplary method 1200 according to some embodiments of the present disclosure. In some embodiments, method 1200 is performed in a terminal device, such as second terminal device 120 of FIG. 1. Additionally or alternatively, method 1200 may be performed in first terminal device 110 or other terminal devices not shown in FIG. 1. For purposes of discussion, and without loss of generality, second terminal device 120 will be described as performing method 1200 with reference to FIG. 1.

[0172] In block 1210, the second terminal device 120 transmits a plurality of reference signals over a sidelink channel to the first terminal device 110 in a time window. In block 1220, the second terminal device 120 determines an average received power of the plurality of reference signals measured by the first terminal device 110 in the time window. In block 1230, the second terminal device 120 determines a path loss of the sidelink channel based on the difference between the average received power and the average transmitted power of the plurality of reference signals.

[0173] In some embodiments, determining the average received power includes receiving a plurality of measurement reports from the first terminal device 110 during a time window, the plurality of measurement reports respectively reporting a plurality of received power amplitudes for a plurality of reference signals, and averaging the plurality of received power amplitudes to obtain the average received power.

[0174] In some embodiments, the measurement reports are received in at least one of a predefined set of transmission resources for the PSSCH from the first terminal device 110 to the second terminal device 120, a selected set of transmission resources for the PSSCH, where the selected set is indicated in an instruction sent from the first terminal device 110 to the second terminal device 120, a MAC CE sent from the first terminal device 110 to the second terminal device 120, and a set of transmission resources for the PSFCH from the first terminal device 110 to the second terminal device 120.

[0175] In some embodiments, determining the average received power includes receiving a measurement report from the first terminal device 110 in a time window to report the average received power, and obtaining the average received power from the measurement report.

[0176] In some embodiments, the measurement report is received in at least one of a predefined set of transmission resources for the PSSCH from the first terminal device 110 to the second terminal device 120, a selected set of transmission resources for the PSSCH, where the selected set is indicated in an instruction sent from the first terminal device 110 to the second terminal device 120, a MAC CE sent from the first terminal device 110 to the second terminal device 120, and a set of transmission resources for the PSFCH from the first terminal device 110 to the second terminal device 120.

[0177] In some embodiments, determining the path loss includes determining the difference between the average received power and the average transmitted power as the path loss, or performing Layer 3 filtering on the difference to obtain the path loss.

[0178] 13 illustrates a flowchart of another exemplary method 1300 according to some embodiments of the present disclosure. In some embodiments, method 1300 is performed in a terminal device, such as second terminal device 120 of FIG. 1. Additionally or alternatively, method 1300 may be performed in first terminal device 110 or another terminal device not shown in FIG. 1. For purposes of discussion, and without loss of generality, second terminal device 120 will be described as performing method 1300 with reference to FIG. 1.

[0179] In block 1310, the second terminal device 120 receives a measurement report from the first terminal device 110 for reporting the received power of a reference signal measured by the first terminal device 110. The reference signal is transmitted from the second terminal device to the first terminal device via a sidelink channel. In block 1320, the second terminal device 120 determines the transmit power of the reference signal. In block 1330, the second terminal device 120 determines a path loss of the sidelink channel based on the received power and the transmit power.

[0180] In some embodiments, determining the transmit power includes determining a PSSCH associated with the PSFCH in response to receiving a measurement report on the PSFCH, and determining a transmit power of a reference signal associated with the PSSCH.

[0181] In some embodiments, determining the transmit power includes: determining a sequence number of a second time-frequency resource in the second ordered set of time-frequency resources in response to receiving the measurement report on the second time-frequency resource in the second ordered set of time-frequency resources; determining a first time-frequency resource in the first ordered set of time-frequency resources based on the sequence number, wherein each time-frequency resource in the first ordered set is associated with a respective time-frequency resource in the second ordered set; and determining a transmit power of a reference signal transmitted on the first time-frequency resource.

[0182] In some embodiments, determining the transmission power includes determining, in a measurement report, a first time point at which the second terminal device 120 transmits a reference signal, and obtaining the transmission power of the reference signal transmitted at the first time point.

[0183] In some embodiments, determining the transmission power includes determining a second time point at which the second terminal device 120 receives a measurement report, determining a time difference between the first time point and the second time point in the measurement report, determining the first time point based on the second time point and the time difference, and obtaining the transmission power of a reference signal transmitted at the first time point.

[0184] In some embodiments, determining the path loss includes determining the difference between the received power and the transmitted power and performing Layer 3 filtering on the difference to obtain the path loss.

[0185] In some embodiments, determining the path loss includes determining a previous transmit power of a reference signal before it is transmitted from the second terminal device 120 to the first terminal device 110, adjusting the receive power using the transmit power and the previous transmit power to obtain an adjusted receive power, and determining the path loss based on the difference between the transmit power and the filtered receive power.

[0186] 14 shows a flowchart of another exemplary method 1400 according to some embodiments of the present disclosure. In some embodiments, method 1400 is performed in a terminal device, for example, second terminal device 120 of FIG. 1. Additionally or alternatively, method 1400 may be performed in first terminal device 110 or another terminal device not shown in FIG. 1. For purposes of discussion, and without loss of generality, second terminal device 120 will be described as performing method 1400 with reference to FIG. 1.

[0187] In block 1410, the second terminal device 120 transmits information to the first terminal device 110, causing the first terminal device 110 to perform Layer 3 filtering on the received power of a reference signal measured by the first terminal device 110. The reference signal is transmitted from the second terminal device 120 to the first terminal device 110 via a sidelink channel. In block 1420, the second terminal device 120 receives a measurement report from the first terminal device 110 for reporting the filtered received power. In block 1430, the second terminal device 120 determines a path loss of the sidelink channel based on the information and the filtered received power.

[0188] In some embodiments, the information includes a transmit power of a reference signal and a reference transmit power of a reference signal shared between first terminal device 110 and second terminal device 120.

[0189] In some embodiments, determining the path loss includes determining the difference between the reference transmit power and the filtered receive power as the path loss.

[0190] In some embodiments, the information includes the transmit power of the reference signal and the previous transmit power of the reference signal before it is transmitted from second terminal device 120 to first terminal device 110.

[0191] In some embodiments, determining the path loss includes determining the difference between the transmit power and the filtered receive power as the path loss.

[0192] 15 is a simplified block diagram of an apparatus 1500 capable of implementing some embodiments of the present disclosure. The apparatus 1500 may be considered another exemplary embodiment of the first terminal device 110, the second terminal device 120, and the network device 130 of FIG. 1. Thus, the apparatus 1500 may be implemented in, or at least as part of, the first terminal device 110, the second terminal device 120, and the network device 130.

[0193] As shown in the figure, the apparatus 1500 includes a processor 1510, a memory 1520 coupled to the processor 1510, a suitable transmitter (TX) and receiver (RX) 1540 coupled to the processor 1510, and a communication interface coupled to the TX / RX 1540. The memory 1520 stores at least a portion of a program 1530. The TX / RX 1540 is used for bidirectional communication. The TX / RX 1540 has at least one antenna for facilitating communication, although in practice, the access nodes referred to in this application may have multiple antennas. The communication interface may refer to any interface for communication with other network elements, such as an X2 interface for bidirectional communication between gNBs or eNBs, an S1 interface for communication between a mobility management entity (MME) / service gateway (S-GW) and a gNB or eNB, an Un interface for communication between a gNB or eNB and a relay node (RN), or a Uu interface for communication between a gNB or eNB and a terminal device.

[0194] The program 1530 includes program instructions that, when executed by an associated processor 1510, cause the device 1500 to operate in accordance with embodiments of the present disclosure, as described herein with reference to Figures 11-14. The embodiments of the present disclosure may be implemented by computer software or hardware executable by the processor 1510 of the device 1500, or a combination of software and hardware. The processor 1510 is configured to implement various embodiments of the present disclosure. The processor 1510 and memory 1520, in combination, form a processing means 1550 capable of implementing various embodiments of the present disclosure.

[0195] Memory 1520 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as, but not limited to, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. While only one memory 1520 is shown in device 1500, device 1500 may include several physically distinct memory modules. Processor 1510 may be of any type suitable for a local technology network, such as, but not limited to, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor with a multi-core processor architecture. Device 1500 may have multiple processors, e.g., dedicated integrated circuit chips, each slaved in time to a clock synchronized with the main processor.

[0196] The devices and / or components included in the devices of the present disclosure may be implemented in various forms, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units are implemented by software and / or firmware, e.g., machine-executable instructions stored on a storage medium. Other than or instead of machine-executable instructions, the devices and / or some or all units in the devices may be implemented, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that may be used include, but are not limited to, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip systems (SOCs), complex programmable logic devices (CPLDs), etc.

[0197] In general, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects are implemented in hardware, while other aspects are implemented in software, or firmware executed by a controller, microprocessor, or other computing device. Although aspects of the embodiments of the present disclosure may be shown and described as block diagrams, flowcharts, or represented in some other graphical form, it is understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special purpose circuits or logic, general purpose hardware, or a controller or other computing device, or some combination thereof.

[0198] The present disclosure further provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, e.g., those computer-executable instructions included in program modules, which, when executed by a device on a target real or virtual processor, perform the processes or methods described above with reference to any of Figures 11-14. Generally, program modules include routines, programs, bases, objects, categories, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or decomposed among program modules as desired. The machine-executable instructions of the program modules may be executed in a local or distributed device. In a distributed device, the program modules may be located in both local and remote storage media.

[0199] Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code performs the specified functions / acts in the flowcharts and / or block diagrams. The program code may be executed entirely on a machine, partially on a machine, as a separate software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0200] The program code may be embodied in a machine-readable medium, which is any tangible medium that contains or stores a program for use with or in conjunction with an instruction execution system, device, or apparatus. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus, or any suitable combination of the above. More specific examples of machine-readable storage media include an electrical connection having one or more wires, a portable computer magnetic disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable optical disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0201] Furthermore, although acts are shown in a particular order, it should not be understood that the acts or all acts shown need to be performed in the particular order shown, or in any order shown, to achieve desired results. In some cases, multitasking and parallel processing may be advantageous. Similarly, while the above discussion includes details of several specific embodiments, this should not be construed as a limitation on the scope of the disclosure, but rather as a description of features specific to particular embodiments. Some features described in a single embodiment may be combined and implemented in a single embodiment. Conversely, various features described in a single embodiment may be implemented in multiple embodiments, alone or in any suitable subcombination.

[0202] Although the present disclosure has described structure features and / or method acts in specific language, the present disclosure, as defined in the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. 1. A method performed by a first terminal device, comprising: receiving a physical sidelink shared channel (PSSCH) demodulation (DM)-reference signal (RS) from a second terminal device; transmitting a measurement report to the second terminal device to report a reference signal received power (RSRP) obtained from the PSSCH DM-RS based on an event associated with a threshold, wherein the RSRP is a higher layer filtered RSRP. the higher layer filtered RSRP is used by the second terminal device to determine a path loss of a sidelink channel based on a difference between a higher layer filtered transmit power of the PSSCH DM-RS and the higher layer filtered RSRP.

2. The method of claim 1 , wherein the RSRP is an average received power associated with PSSCH DM-RS received via multiple antenna ports of the first terminal device.

3. The method of claim 1 , wherein the higher layer filtered RSRP is filtered based on filter coefficients configured for the DM-RS.

4. A method performed by a second terminal device, comprising: transmitting a physical sidelink shared channel (PSSCH) demodulation (DM)-reference signal (RS) to a first terminal device; receiving, from the first terminal device, a measurement report for reporting a reference signal received power (RSRP) obtained from the PSSCH DM-RS, the RSRP being reported by the first terminal device based on an event associated with a threshold, the RSRP being a higher layer filtered RSRP; determining a path loss of a sidelink channel based on a difference between a higher layer filtered transmit power of the PSSCH DM-RS and a higher layer filtered RSRP.

5. The method of claim 4, wherein the RSRP is an average received power associated with PSSCH DM-RS received via multiple antenna ports of the first terminal device.

6. The method of claim 4, wherein the higher layer filtered RSRP is filtered based on filter coefficients configured for the DM-RS.

7. means for receiving a Physical Sidelink Shared Channel (PSSCH) demodulation (DM)-Reference Signal (RS) from a second terminal device; means for transmitting a measurement report to the second terminal device to report a reference signal received power (RSRP) obtained from the PSSCH DM-RS based on an event associated with a threshold, wherein the RSRP is a higher layer filtered RSRP; The higher layer filtered RSRP is used by the second terminal device to determine a path loss of a sidelink channel based on a difference between a higher layer filtered transmit power of the PSSCH DM-RS and the higher layer filtered RSRP. A first terminal device.

8. The first terminal device of claim 7, wherein the RSRP is an average received power associated with PSSCH DM-RS received via multiple antenna ports of the first terminal device.

9. The first terminal device according to claim 7, wherein the higher layer filtered RSRP is filtered based on a filter coefficient set for the DM-RS.

10. means for transmitting a Physical Sidelink Shared Channel (PSSCH) Demodulation (DM)-Reference Signal (RS) to a first terminal device; means for receiving, from the first terminal device, a measurement report for reporting a reference signal received power (RSRP) obtained from the PSSCH DM-RS, the RSRP being reported by the first terminal device based on an event associated with a threshold, the RSRP being a higher layer filtered RSRP; means for determining a path loss of a sidelink channel based on a difference between a higher layer filtered transmit power of the PSSCH DM-RS and a higher layer filtered RSRP; A second terminal device comprising:

11. The second terminal device of claim 10, wherein the RSRP is an average received power associated with PSSCH DM-RS received via multiple antenna ports of the first terminal device.

12. The second terminal device according to claim 11, wherein the higher layer filtered RSRP is filtered based on a filter coefficient set for the DM-RS.

13. 1. A method performed by a first terminal device, comprising: receiving a Physical Sidelink Shared Channel (PSSCH) demodulation (DM)—Reference Signal (RS); transmitting a measurement report to report reference signal received power (RSRP) obtained from the PSSCH DM-RS; transmitting the measurement report In response to transmitting the PSSCH DM-RS on a first time frequency resource in a first ordered set of time frequency resources, determining a sequence number of the first time frequency resource in the first ordered set of time frequency resources; selecting second time-frequency resources from a second ordered set of time-frequency resources based on the sequence number, wherein each time-frequency resource in the second ordered set is associated with a respective time-frequency resource in the first ordered set; transmitting the measurement report in the second time frequency resource.

14. A method performed by a second terminal device, comprising: transmitting a physical sidelink shared channel (PSSCH) demodulation (DM)-reference signal (RS) to a first terminal device; receiving a measurement report from the first terminal device for reporting a reference signal received power (RSRP) obtained from the PSSCH DM-RS; determining a transmission power of the PSSCH DM-RS; determining a path loss for a sidelink channel based on a difference between the RSRP and the transmit power; determining the transmit power determining a sequence number of a second time frequency resource in a second ordered set of time frequency resources in response to the measurement report being received on the second time frequency resource in the second ordered set of time frequency resources; determining a first time-frequency resource in a first ordered set of time-frequency resources based on the sequence number, wherein each time-frequency resource in the first ordered set is associated with a respective time-frequency resource in the second ordered set; determining the transmit power of the PSSCH DM-RS transmitted on the first time frequency resource.

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