Communication method, terminal device, and network device

Abstract

To provide a method of establishing a phase tracking reference signal (PT-RS), a terminal device, a network device, and a computer-readable medium.SOLUTION: In a communication process 200, a terminal device receives control information indicating a resource set and transmission configuration instruction (TCI) status for communication between a terminal device and a network device from a network device (205), determines a resource subset that is a frequency domain portion of the resource set associated with each TCI state (215), determines a mapping of a phase tracking reference signal (PT-RS) to the resource subset (225), and performs PT-RS transmission between the network device and the terminal device (230) after determining the mapping of PT-RS to the resource subset.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of communications, and more particularly to solutions for configuring phase tracking reference signals (PT-RS).

Background Art

[0002] In 3GPP meeting RAN#81, new work items (WIs) for NR eMIMO were approved, including the following. First, enhanced multi-user (MU) multiple-input multiple-output (MIMO) support is provided. Specifically, overhead reduction is defined based on type II channel state information (CSI) feedback, considering the trade-off between performance and overhead. The type II CSI feedback is considered for and defined for expansion to rank >2 as needed. Second, enhanced multi-TRP / panel transmission is provided, including improved reliability and robustness for both ideal and non-ideal backhaul. In particular, enhanced downlink control signaling is defined to effectively support non-coherent joint transmission. Enhanced uplink control signaling and / or reference signals for non-coherent joint transmission are considered and defined as needed. The multi-TRP technology for ultra-reliable low-latency communication (URLLC) requirements is included in this WI.

[0003] Thirdly, enhancements for multi-beam operations mainly targeting FR2 operations are provided. Specifically, to reduce latency and overhead, enhancements to the selection of uplink (UL) and / or downlink (DL) transmission beams defined in Rel-15 are considered and defined as necessary. UL transmission beam selection for multi-panel operations is defined to facilitate panel-specific beam selection. Beam failure recovery for secondary cells (SCells) is defined based on the beam failure recovery defined in Rel-15. Measurement and reporting of L1-reference signal received quality (RSRQ) or L1-signal-to-interference plus noise ratio (SINR) are defined. Fourthly, research and summary are conducted at the first RAN1 meeting after the start of WI, and if necessary, CSI-RS and demodulation reference signals, DMRS (both for downlink and uplink) are enhanced to reduce the peak-to-average power ratio (PAPR) of one or more layers (the resource element (RE) mapping defined in Rel-15 is not changed).

Summary of the Invention

[0004] Overall, exemplary embodiments of the present disclosure provide a solution for setting a phase tracking reference signal (PT-RS).

[0005] In a first aspect, a method for communication is provided. The method includes receiving, at a terminal device, control information from a network device indicating a resource set and a transmission configuration indication (TCI) state for communication between the terminal device and the network device. The method further includes determining a resource subset that is a part in the frequency domain of the resource set associated with each TCI state. The method further includes determining a mapping of the PT-RS to the resource subset.

[0006] In a second aspect, a communication method is provided. The method includes, in a network device, transmitting to a terminal device control information indicating a resource set and a TCI state for communication between the terminal device and the network device. The method further includes determining a resource subset that is a part in the frequency domain of the resource set, which is associated with each TCI state. The method further includes determining a mapping from PT-RS to the resource subset.

[0007] In a third aspect, a terminal device is provided. The terminal device includes a processor and a memory in which instructions are stored. The memory and the instructions are configured, together with the processor, to cause the terminal device to execute the method according to the first aspect.

[0008] In a fourth aspect, a network device is provided. The network device includes a processor and a memory in which instructions are stored. The memory and the instructions are configured, together with the processor, to cause the network device to execute the method according to the second aspect.

[0009] In a fifth aspect, a computer-readable medium storing instructions is provided. When the instructions are executed by at least one processor of a device, the instructions cause the device to execute the method according to the first aspect or the second aspect.

[0010] It should be understood that the summary of the invention is not intended to identify key or essential 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 understood from the following description.

Brief Description of the Drawings

[0011] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of some embodiments of the present disclosure in the accompanying drawings. In the drawings:

[0012]

Figure 1

[0013]

Figure 2

[0014]

Figure 3

[0015]

Figure 4

[0016]

Figure 5

[0017]

Figure 6

[0018] Throughout the drawings, the same or similar reference numerals denote the same or similar elements.

Mode for Carrying Out the Invention

[0019] Hereinafter, the principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are described only for the purpose of explanation and to assist those skilled in the art in understanding and implementing the present disclosure, and do not imply any limitation to the scope of the present disclosure. The disclosure described in the present text can be implemented in various ways different from the methods described below.

[0020] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0021] As used herein, the term "network device" or "base station" (BS) means a device that can provide or host a cell or coverage with which a terminal device can communicate. Examples of network devices include, but are not limited to, Node B (NodeB or NB), evolved Node B (eNodeB or eNB), next-generation Node B (gNB), infrastructure devices for V2X (vehicle-to-everything) communication, transmission / reception point (TRP), remote radio unit (RRU), radio head (RH), remote radio head (RRH), low-power nodes (such as femto nodes, pico nodes, etc.).

[0022] As used herein, the term "terminal device" means 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 acquisition devices such as digital cameras, gaming devices, music storage and playback devices, or Internet devices that enable wireless or wired Internet access and browsing. For the sake of discussion, hereinafter, in some embodiments, an example of a terminal device, UE, will be referred to for explanation, and the terms "terminal device" and "user equipment" (UE) can be used interchangeably in the context of this disclosure.

[0023] In one embodiment, the terminal device can be connected to a first network device and a second network device. It is possible to use one of the first network device and the second network device as a master node and the other as a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, it is possible to use the first network device as a first RAT device and the second network device as a second RAT device. In one embodiment, the first RAT device is an eNB and the second RAT device is a gNB. Information regarding different RATs can be transmitted from at least one of the first network device and the second network device to the terminal device. In one embodiment, the first information may be transmitted from the first network device to the terminal device, and the second information may be transmitted from the second network device directly or via the first network device to the terminal device. In one embodiment, information related to the configuration of the terminal device constituted by the second network device may be transmitted from the second network device via the first network device. Information regarding the resetting of the terminal device constituted by the second network device may be transmitted directly from the second network device to the terminal device or via the first network device to the terminal device.

[0024] As used herein, the terms "transmission and reception point", "transmission / reception point", or "transmission and reception point" can generally indicate a station that communicates with a user equipment. However, the transmission and reception point can be called by different terms, such as a base station (BS), a cell, a Node B, an evolved Node B (eNB), a next-generation Node B (gNB), a transmission and reception point (TRP), a sector, a site, a base transceiver system (BTS), an access point (AP), a relay node (RN), a remote radio head (RRH), a radio unit (RU), an antenna, etc.

[0025] That is, in the context of the present disclosure, a transmission and reception point, a base station (BS) or a cell can be interpreted as a comprehensive concept indicating an area or a part of a function covered by a base station controller (BSC) in code division multiple access (CDMA), a Node B in WCDMA, an eNB or a sector (site) in LTE, a gNB or a TRP in NR, etc. Therefore, the concepts of a transmission and reception point, a base station (BS) and / or a cell can include various coverage areas such as a megacell, a macrocell, a microcell, a picocell, a femtocell, etc. Further, such concepts can include the communication range of a relay node (RN), a remote radio head (RRH), or a radio unit (RU).

[0026] In the context of the present disclosure, a user equipment and a transmission / reception point can be regarded as two comprehensive transmission / reception entities having a comprehensive meaning for embodying the technologies and technical concepts disclosed herein, and should not be limited to specific terms or words. Note that the user equipment and the transmission / reception point can be regarded as an uplink or downlink transmission / reception entity having a comprehensive meaning for embodying the technologies and technical concepts disclosed in relation to the present embodiment, and should not be limited to specific terms or words. In this specification, uplink (UL) transmission / reception is a scheme in which data is transmitted from a user equipment to a base station. Instead, downlink (DL) transmission / reception is a scheme in which data is transmitted from a base station to a user equipment.

[0027] As used herein, the terms "resource", "transmission resource", "resource block", "physical resource block", or "sidelink resource" can refer to any resource used to perform communication (e.g., communication between a terminal device and a network device), such as a resource in the time domain, a resource in the frequency domain, a resource in the spatial domain, a resource in the code domain, or any other resource that enables communication. In the following, some embodiments of the present disclosure will be described by taking resources in both the frequency domain and the time domain as examples of transmission resources. It should be noted that the embodiments of the present disclosure are similarly applicable to other resources in other domains.

[0028] As used herein, the singular forms "a", "one", and "the" include the plural forms as well, unless explicitly stated otherwise in the context. The term "including" and its variants should be understood as open-ended terms meaning "including but not limited to". The term "based on" should be understood as "at least partially based on". The terms "an embodiment" and "embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first", "second", etc. can refer to different or the same objects. In the following, both explicit definitions and implicit definitions can be included.

[0029] In some examples, a value, procedure, or device is referred to as "best", "lowest", "highest", "minimum", "maximum", etc. Such descriptions are intended to indicate that a selection can be made from among many available functional alternatives, and it should be understood that such a selection does not have to be better, smaller, higher, or otherwise more preferred than other selections.

[0030] FIG. 1 is a schematic diagram of a communication environment 100 in which some embodiments of the present disclosure can be implemented. The communication environment 100 includes a network device 110 and a terminal device 120 that receives services from the network device 110. The service area of the network device 110 can be referred to as a cell 102. In the communication environment 100, the network device 110 can transmit data and control information to the terminal device 120, and the terminal device 120 can also transmit data and control information to the network device 110. The communication link from the network device 110 to the terminal device 120 is called a downlink (DL) or forward link, and the communication link from the terminal device 120 to the network device 110 is called an uplink (UL) or reverse link.

[0031] As shown in FIG. 1, the network device 110 is coupled to two TRPs 131 and 132 and can communicate with the terminal device 120 via these two TRPs 131 and 132. For example, in iterative transmissions between the network 110 and the terminal device 120, such as multi-TRP URLLC transmissions, the network device 110 can transmit and receive the same data 140 via the TRPs 131 and 132. As used herein, the data 140 can include any data that can be transmitted between the network device 110 and the terminal device 120, including user plane data, control plane data, etc. For example, the data 140 may be a transport block (TB) or a packet. Hereinafter, the TRP 131 may be referred to as the first TRP, and the TRP 132 may be referred to as the second TRP. The first TRP 131 and the second TRP 132 may be included in the same serving cell (e.g., the cell 102 shown in FIG. 1) or in different serving cells provided by the network device 110.

[0032] In some embodiments, the first TRP131 and the second TRP132 can be explicitly associated with different upper layer configuration identities. For example, an index set by the upper layer can be associated with a pre-defined control resource set (CORESET), a pre-defined reference signal (RS), or a pre-defined transmission configuration indication (TCI) state for distinguishing transmissions between different TRPs and the terminal device 120. When the terminal device 120 receives two DCIs from two CORESETs associated with different identities set by the upper layer, these two DCIs are indicated by different TRPs. Further, the first TRP131 and the second TRP132 can be implicitly identified by dedicated settings of physical channels or signals. For example, dedicated CORESET, RS, and TCI states associated with a TRP are used to identify transmissions from different TRPs to the terminal device 120. For example, when the terminal device 120 receives a DCI from a dedicated CORESET, the DCI is indicated by the associated TRP dedicated to the CORESET.

[0033] In iterative transmission or reception via these two TRP131 and 132, the network device 110 can use one of a plurality of available iterative schemes. The iterative scheme can specify, for the network device 110, a transmission method for using these two TRP131 and 132 in cooperation, such as a multiplexing scheme between these two TRP131 and 132, respective resource allocations for these two TRP131 and 132, and the like.

[0034] For example, to facilitate further down-selection of one or more schemes in 3GPP meeting RAN1#96bis, some schemes of multi-TRP-based URLLC scheduled by a single DCI are made explicit at least as follows.

[0035] Scheme 1 (SDM): In a single slot, there are n (n ≤ N s ) TCI states with overlapping time and frequency resource allocations.

[0036] Scheme 1a: Each transmission occasion is the same layer or set of layers of the same TB, and each layer or set of layers is associated with one TCI and one set of (multiple) DMRS ports. A single codeword with one RV is used across all spatial layers or sets of layers. From the UE's perspective, different coded bits are mapped to different layers or sets of layers using the same mapping rules as in Rel-15.

[0037] Scheme 1b: Each transmission occasion is the same layer or set of layers of the same TB, and each layer or set of layers is associated with one TCI and one set of (multiple) DMRS ports. A single codeword with one RV is used for each spatial layer or set of layers. The RVs corresponding to each spatial layer or set of layers may be the same or different. The codeword-layer mapping for the case where the total number of layers ≤ 4 is for future consideration.

[0038] Scheme 1c: One transmission occasion is one layer of the same TB where one DMRS port is associated with multiple TCI state indices, or one layer of the same TB where multiple DMRS ports are associated one-to-one with multiple TCI state indices.

[0039] Furthermore, it has been shown that it is possible to discuss applying different MCS / modulation orders to different layers or sets of layers.

[0040] Scheme 2 (FDM): n (n ≤ N fThere are [[ID=]], and have non-overlapping frequency resource allocations. Each of the non-overlapping frequency resource allocations is associated with one TCI state. The same single / multiple DMRS ports are associated with all non-overlapping frequency resource allocations.

[0041] Scheme 2a: A single codeword with one RV is used across the entire resource allocation. From the UE's perspective, a common RB mapping (e.g., the codeword-layer mapping in Rel-15) is applied across the entire resource allocation.

[0042] Scheme 2b: A single codeword with one RV is used for each of the non-overlapping frequency resource allocations. The RV corresponding to each of the non-overlapping frequency resource allocations may be the same or different.

[0043] Furthermore, it is shown that it is possible to discuss applying different MCS / modulation orders to different non-overlapping frequency resource allocations. It is also shown that it is possible to discuss the details of the frequency resource allocation mechanism of FDM 2a / 2b regarding the allocation granularity and time-domain allocation.

[0044] Scheme 3 (TDM): There are n (n ≤ N t1 ) TCI states in a single slot and have non-overlapping time resource allocations. Each transmission occasion of the TB has one TCI and one RV at the time granularity of a micro-slot. All transmission occasions within the slot use a common MCS with the same single or multiple DMRS ports. The RV / TCI state may be the same or different between transmission occasions. Channel estimation interpolation between minislots with the same TCI index is for future consideration.

[0045] Scheme 4 (TDM): Has n (n ≤ N t2There are TCI states. Each transmission occasion of TB has one TCI and one RV. All transmission occasions over K slots use a common MCS with the same single or multiple DMRS ports. Between transmission occasions, the RV / TCI states may be the same or different. Channel estimation interpolation between slots with the same TCI index is for future consideration. Note that the URLLC scheme based on M-TRP / panel should be compared in terms of improved reliability, efficiency, and specification impact. Note that it can be discussed about the support for the number of layers per TRP.

[0046] Furthermore, before transmitting data 140 to the terminal device 120, the network device 110 can transmit control information 135 related to the transmission of data 140. For example, the control information 135 can schedule a resource set for the transmission of data 140 and include various transmission parameters related to the transmission of data 140, such as one or more TCI states, frequency domain resource allocation (FDRA), time domain resource allocation (TDRA) that can include a slot offset and a start / length indicator value, a demodulation reference signal (DMRS) group, and a redundancy version (RV), as defined in the 3GPP specification. It should be understood that the transmission parameters indicated by the control information 135 are not limited to those as described above. The embodiments of the present disclosure can be similarly applied to control information including any transmission parameters.

[0047] In some embodiments, the control information 135 may be a DCI defined in the 3GPP specification that can dynamically (i.e., on a relatively short time scale) indicate various transmission parameters. In some other embodiments, the control information 135 may be a radio resource control (RRC) message or a media access control (MAC) control element (CE) message that can semi-statically (i.e., on a relatively long time scale) indicate various transmission parameters.

[0048] Some embodiments of the present disclosure are described with reference to a first TRP 131 and a second TRP 132 within the same serving cell provided by the network device 110. These examples are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing the present disclosure, and do not imply any limitation on the scope of the present disclosure. It should be understood that the embodiments of the present disclosure described herein can be implemented in various ways different from the methods described below.

[0049] It should be understood that the number of network devices, the number of terminal devices, and the number of TRPs shown in FIG. 1 are used for illustrative purposes only and do not imply any limitation. In fact, the communication environment 100 can include any appropriate number of network devices, any appropriate number of terminal devices, and any appropriate number of TRPs suitable for implementing the embodiments of the present disclosure. In other words, the embodiments of the present disclosure are also applicable to scenarios where a terminal device communicates with a network device coupled to one or more network devices or two or more TRPs.

[0050] Communication in the communication environment 100 can comply with any appropriate standard including, but not limited to, Global System for Mobile Communications (GSM), Extended Coverage GSM 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. Furthermore, the communication can be executed according to any generation of communication protocol known currently or developed in the future. Examples of communication protocols include, but are not limited to, the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols.

[0051] As specified in the 3GPP specification, for a CORESET in which a UE schedules a Physical Downlink Shared Channel (PDSCH), when the upper layer parameter tci-PresentInDCI is set to "valid", the UE assumes that a TCI field exists in DCI format 1_1 of the PDCCH transmitted in the CORESET. When tci-PresentInDCI is not set for the CORESET that schedules the PDSCH, or when the PDSCH is scheduled by DCI format 1_0, to determine the PDSCH antenna port quasi-collocation, the UE assumes that the TCI state of the PDSCH is the same as the TCI state applied to the CORESET for PDCCH transmission.

[0052] When tci-PresentInDCI is set to "valid", when the PDSCH is scheduled in DCI format 1_1, the UE should determine the PDSCH antenna port quasi-collocation using the TCI-State according to the value of the "transmission configuration indication" field in the PDCCH detected using the DCI. When the time offset between the reception of the DL DCI and the corresponding PDSCH is greater than or equal to the threshold Threshold-Sched-Offset (threshold scheduling offset) (where the threshold is based on the reported UE capabilities), the UE can assume that the DM-RS ports of the PDSCH of the serving cell and the (multiple) RSs in the TCI state are quasi-collocated with respect to the (multiple) quasi-collocation (QCL) type parameters given by the indicated TCI state.

[0053] In the current specification, a TCI field may exist in downlink control information (DCI), the terminal device may be configured with a TCI state, and the TCI state may include parameters for configuring the QCL relationship between one or two downlink reference signals and the DMRS ports of the PDSCH. The terminal device may be configured by the DMRS type and / or the maximum number / length of the DMRS and / or the number of codewords. When the terminal device is configured with a given DMRS type, a predetermined value of the maximum number / length of the DMRS, and a value of the predetermined number of codewords, there is a corresponding table for indicating at least one of the antenna port, the number of (multiple) DMRS CDM groups without data, the number of front-loaded DMRS symbols, the number of (multiple) DMRS ports, and the (multiple) indices of the (multiple) DMRS ports.

[0054] In some embodiments, when one or more (e.g., two) DMRS groups are configured for the terminal device, one or two TCI states configured within one DCI of that terminal device may exist. In some embodiments, the number of TCI states within one DCI depends on the QCL relationship between the DMRS ports from two DMRS groups. For example, if the DMRS ports from two DMRS groups are not QCL with each other for at least one of QCL-TypeA (QCL type A), QCL-TypeB (QCL type B), QCL-TypeC (QCL type C), and QCL-TypeD (QCL type D), the number of TCI states in one DCI may be 2. Further, for example, if the DMRS ports from two DMRS groups are QCL with each other regarding {Doppler shift, Doppler spread, average delay, average spread, spatial Rx parameter} and / or average gain, the TCI state in one DCI may be 1.

[0055] In some embodiments, the number of TCI states within one DCI depends on the number of DMRS ports. For example, when the number of DMRS ports is 2, the number of TCI states within one DCI may be 2. For example, the two TCI states within one DCI may be the same or different from each other. Also, for example, when the number of DMRS ports is 1, the number of TCI states within one DCI may be 1.

[0056] Generally, a network device (e.g., eNB or gNB) can transmit downlink reference signals (RS) such as demodulation reference signals (DMRS), channel state information reference signals (CSI-RS), sounding reference signals (SRS), phase tracking reference signals (PT-RS), and mini-time frequency tracking reference signals (TRS). A terminal device (e.g., user equipment) within the system can receive the downlink RS on the allocated resources. The terminal device can also transmit the uplink RS to the network device on the corresponding allocated resources. To indicate the allocated resources for the RS and / or other necessary information, the network device can transmit the RS configuration to the terminal device before transmitting the RS.

[0057] In other words, in addition to normal data communication, the network device 110 can transmit one or more downlink reference signals (RS) to one or more terminal devices 120 in a broadcast, multicast, and / or unicast manner in the downlink (DL). Similarly, one or more terminal devices 120 can transmit the RS to the network device 110 in the uplink (UL). Examples of the RS can include, but are not limited to, downlink or uplink demodulation reference signals (DMRS), channel state information reference signals (CSI-RS), sounding reference signals (SRS), phase tracking reference signals (PT-RS), mini-time frequency tracking reference signals (TRS), etc.

[0058] As used herein, a RS is a sequence of signals (also referred to as a "RS sequence") known to both the network device 110 and the terminal device 120. For example, the network device 110 can generate and transmit a RS sequence based on a specific rule, and the terminal device 120 can derive the RS sequence based on the same rule. In the transmission of downlink RS and uplink RS, the network device 110 can allocate corresponding resources (also referred to as "RS resources") for transmission and / or specify which RS sequence should be transmitted.

[0059] In some scenarios, both the network device 110 and the terminal device 120 are equipped with multiple antenna ports (or antenna elements) and can transmit a specified RS sequence through the antenna ports (antenna elements). A set of RS resources associated with the multiple RS ports is also specified. An RS port can be referred to as a specific mapping to one or more resource elements (REs) of a resource region allocated for RS transmission in the time domain, frequency domain, and / or code domain, for a part or all of the RS sequence. Such resource allocation information may be instructed to the terminal device 120 before the transmission of the RS.

[0060] In NR, PT-RS can be introduced to enable the compensation of phase noise. Usually, phase noise increases with the increase of the carrier frequency. Therefore, PT-RS can be used to remove the phase noise of a wireless network operating in a high-frequency band. Currently, PT-RS mapping patterns in the time domain and frequency domain are being studied, but the detailed patterns have not yet been fully designed. For example, the density of PT-RS in the time domain (also called the "time density" of PT-RS) is associated with the scheduled modulation and coding scheme (MCS), and the density of PT-RS in the frequency domain (also called the "frequency density" of PT-RS) and the group pattern of PT-RS ports (e.g., the number of PT-RS groups and the number of samples per PT-RS group) are agreed to be associated with the scheduled BW (e.g., the number of scheduled RBs).

[0061] For an OFDM-based system, the time density of PT-RS can be either zero (i.e., no PT-RS exists), every four symbols (i.e., 1 / 4), every two symbols (i.e., 1 / 2), or every symbol (i.e., 1). The time density of PT-RS is related to the scheduled MCS. For example, Table 5.1.6.3-1 in 3GPP TS 38.214 shows the correlation between the scheduled MCS and the time density of PT-RS as follows. In Table 5.1.6.3-1, ptrs-MCS1 to ptrs-MCS4 each represent the MCS threshold that needs to be set by the network device.

Table 1

[0062] Similarly, the frequency density of PT-RS can be any one of zero (i.e., no PT-RS exists), per RB (i.e., 1), per two RBs (i.e., 1 / 2), or per four RBs (i.e., 1 / 4). The frequency density of PT-RS is associated with the scheduled bandwidth (i.e., the number of scheduled RBs). For example, Table 5.1.6.3-2 in 3GPP TS 38.214 shows the correlation between the scheduled bandwidth (expressed as N RB and the frequency density of PT-RS as follows. In Table 5.1.6.3-2, N RB0 and N RB1 each represent the threshold of the bandwidth that needs to be set by the network device.

Table 2

[0063] The M-TRP URLLC schemes 2a and 2b based on a single DCI are agreed to support the following designs. Comb-like frequency resource allocation between / among TRPs. For the wideband precoding resource block group (PRG), the first ceiling[N_RB / 2] RBs (where ceiling[ ] refers to the ceiling bracket) are allocated to the TCI state 1 (also called TCI state A), and the remaining floor[N_RB / 2] RBs (where floor[ ] refers to the floor bracket) are allocated to the TCI state 2 (also called TCI state B). When the PRG size = 2 or 4, the even-numbered PRGs within the allocated FDRA are allocated to the TCI state 1, and the odd-numbered PRGs within the allocated FDRA are allocated to the TCI state 2.

[0064] Regarding the PRG, as defined in the 3GPP specification, the UE can assume that the precoding granularity is P ’ BWP.i consecutive resource blocks in the frequency domain. P ’ BWP.i can be equal to any one of the values in {2, 4, wideband}. P’ BWP.i When it is determined that it is "wideband", it is not desirable for the UE to be scheduled in non - contiguous PRBs, and the UE can assume that the same precoding is applied to the allocated resources. P ’ BWP.i When it is determined that it is any one value among {2, 4}, the precoding resource block group (PRG) divides the bandwidth part i with P ’ BWP.i P consecutive PRBs. The actual number of consecutive PRBs in each PRG may be one or more.

[0065] In view of the above, for the URLLC scheme 2a / 2b, when the total number of PRB schedulings is N, based on the agreement, a part of the PRBs is allocated to each TCI state. On the other hand, for each TCI state, it is unclear how to determine the specific setting or mapping of the PT - RS. For example, it is not designed how to obtain the PT - RS density and PRBs for the PT - RS mapping.

[0066] To solve the above-described technical problems and potential other technical problems in the conventional solutions, embodiments of the present disclosure provide a solution for setting PT-RS (especially PT-RS presence / density / pattern / offset) based on multi-TRP transmission. In some embodiments, in the case of schemes 2a / 2b based on multi-TRP transmission, the PT-RS presence / density / pattern / offset is determined independently / individually in each part of the scheduled resource. In some other embodiments, the presence / density of PT-RS is the same for two or more parts of the scheduled resource and is determined based on the largest part among the two or more parts. In some other embodiments, the PT-RS offset is the same for two or more parts and is determined based on the smallest part among the two or more parts. Embodiments of the present disclosure provide practical details on how to determine the PT-RS presence / density / pattern / offset when the scheduled resource set is shared by multiple TCI states (especially in the case of schemes 2a / 2b). The principle and implementation of the present invention will be described in detail below.

[0067] FIG. 2 shows an exemplary communication process 200 between a network device 110 and a terminal device 120 according to some embodiments of the present disclosure. For the sake of explanation, the communication process 200 will be described with reference to FIG. 1. However, it should be understood that the communication process 200 is equally applicable to any other communication scenario in which the network device and the terminal device communicate with each other.

[0068] As shown in FIG. 2, the network device 110 transmits 205 control information 135 to the terminal device 120. Thereby, the terminal device 120 receives 205 the control information 135 from the network device 110. In some embodiments, the control information 135 may be downlink control information (DCI) as defined in the 3GPP specifications. In some other embodiments, the control information 135 may include any existing or future signaling as defined in the 3GPP specifications or other standard specifications. The control information 135 can indicate a resource set for communication (e.g., transmission of data 140) between the terminal device 120 and the network device 110 and one or more TCI states.

[0069] In some embodiments, the resource set can include a plurality of physical resource blocks (PRBs) as defined in the 3GPP specifications. However, in some other embodiments, the resource set may be in any other form as defined in the 3GPP specifications or other standard specifications. Further, in some embodiments, the TCI state can include up to 8 TCI states defined in the 3GPP specifications. However, in some other embodiments, the TCI state can include any existing or future transmission configuration indication state having a function similar or identical to the function as defined in the 3GPP specifications. Examples of the resource set and the TCI state are described below with reference to FIG. 3.

[0070] FIG. 3 shows an exemplary resource set 300 divided into two resource subsets 310 and 320 associated with two TCI states (TCI state A and TCI state B) in the frequency domain according to some embodiments of the present disclosure. In FIG. 3, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. As shown, the control information 135 transmitted by the network device 110 to the terminal device 120 can indicate the resource set 300, for example, the time and frequency positions of the resource set 300, and the control information 135 can also indicate two of the eight TCI states defined in the 3GPP specification (for example, TCI state A and TCI state B). The resource set 300, TCI state A, and TCI state B are used for communication (for example, transmission of data 140) between the terminal device 120 and the network device 110.

[0071] Returning to FIG. 2, the network device 110 determines 210 the resource subsets associated with the respective TCI states, and each resource subset is a part of the resource set in the frequency domain. Similarly, the terminal device 120 also determines 215 the resource subsets associated with the respective TCI states. For example, referring to FIG. 3, the network device 110 or the terminal device 120 can determine the resource subset 310 associated with TCI state A and the resource subset 320 associated with TCI state B. Thus, it can be seen that the resource subsets 310 and 320 are two parts of the resource set 300 in the frequency domain.

[0072] It should be understood that the number of TCI states as shown in FIG. 3, the wideband PRG setting of the resource set 300, and the specific division method of the resource set 300 are for illustrative purposes only and do not imply any limitation. In other embodiments, any suitable number of TCI states indicated within the control information 135 may exist, the resource set 300 may have any suitable PRG setting, and the resource set 300 may be divided into any number of subsets associated with the respective TCI states in any suitable manner.

[0073] Returning to FIG. 2, the network device 110 determines 220 the mapping of the PT-RS to the resource subset for each resource subset, for example, whether the PT-RS is to be transmitted to or received from the terminal device 120, and which resources within the resource subset are to be used if the PT-RS is transmitted or received. Similarly, the terminal device 120 also determines 225 the mapping of the PT-RS to the resource subset. For example, referring to FIG. 3, the network device 110 or the terminal device 120 can determine how the PT-RS is mapped to the resources within the resource subsets 310 and 320, respectively. There are various possible options for mapping the PT-RS to the resources within the resource subset, which will be described one by one below.

[0074] In the first option, the PT-RS mapping in each resource subset can be determined independently. For example, the PT-RS mapping in each resource subset can be based on the resources (e.g., PRBs) for each TCI state. Using this straightforward option, an optimal mapping can be set for each of the resource subsets (i.e., for each of the TCI states). In particular, for schemes 2a / 2b, the scheduling PRBs for the PDSCH are split into two parts, and the PT-RS mapping for each part is independent. In other words, the PT-RS presence / pattern / mapping is for each part of the scheduled PRBs.

[0075] More specifically, when the UE is configured with M-TRP URLLC schemes 2a and 2b based on a single DCI, and the UE is configured with one or more (e.g., two or three or four) TCI states at one TCI code point, the PT-RS presence / density / mapping is based on the scheduled PRBs assigned / associated with each TCI state. That is, the network device 110 or the terminal device 120 can determine each value of the mapping parameters (e.g., frequency density of PT-RS, PT-RS resource offset, etc.) for the resource subset. For example, referring to FIG. 3, the mapping of PT-RS to resources may be determined separately for resource subsets 310 and 320. In particular, for scheme 2a / 2b, the PT-RS on the two parts of the scheduled PRBs assigned / associated with the two TCI states is independent.

[0076] In some embodiments, there may be two TCI states at one TCI code point. For example, these two TCI states may be TCI state A and TCI state B. As an example of the first option, the frequency density of PT-RS may be set independently for the resource subset. In this way, the optimal PT-RS frequency density can be determined for each resource subset. Therefore, the network device 110 or the terminal device 120 can determine the frequency density of PT-RS for each of the resource subsets based on the number of resources in the resource subset. For example, as shown in FIG. 3, let the number of resources (e.g., PRBs) (resource subset 310) assigned / associated with TCI state A be N RB_a and the number of resources (e.g., PRBs) (resource subset 320) assigned / associated with TCI state B be N RB_b . For example, the total number of resource blocks of the PDSCH scheduled by a single DCI or the scheduled bandwidth can be set as N RB . For example, N RB_a +N RB_b =N RBIt is as follows.

[0077] Accordingly, the frequency density of PT-RS in the resource subset 310 can be determined based on N RB_a and the frequency density of PT-RS in the resource subset 320 can be determined based on N RB_b For example, based on Table 5.1.6.3-2 defined in 3GPP TS 38.214, the PT-RS frequency density in the resource subset 310 can be determined by replacing the parameter "N RB " with "N RB_a ", and the PT-RS frequency density in the resource subset 320 can be determined by replacing the parameter "N RB " with "N RB_b ".

[0078] As another example of the first option, the PT-RS resource offset may be set independently for each resource subset. In this way, an optimal PT-RS resource offset can be determined for each resource subset. Therefore, the network device 110 or the terminal device 120 can determine, for each of the resource subsets, the offset between the start resource for mapping and the resource having the lowest frequency within the resource subset based on the number of resources, the frequency density, and the identifier of the terminal device. For example, referring to FIG. 3, the PT-RS resource offset in the resource subset 310 can be determined based on N RB_a and the PT-RS resource offset in the resource subset 320 can be determined based on N RB_b

[0079] More specifically, based on the following formula (1) defined in section 7.4.1.2.2 of 3GPP TS 38.211, the PT-RS resource offset in the resource subset 310 is obtained by replacing the parameter "N RB " with "N RB_a ​can be determined by replacing it with "", and the PT-RS resource offset in the resource subset 320 is the parameter "N" RB is replaced with "N" RB_b can be determined by replacing it with "". The other parameters in Equation (1) are defined in the 3GPP specifications.

Number

[0080] In some embodiments, using the first option described above, Section 5.1.6.3 of the current technical specification 3GPP TS 38.214 can be updated as follows. 5.1.6.3 PT-RS Reception Procedure When the UE is configured with M-TRP URLLC schemes 2a and 2b based on a single DCI (and / or when the UE is configured with multiple (e.g., 2 or 3 or 4) TCI states at one TCI code point), the UE should assume the presence and pattern of the PT-RS antenna ports based on each part of the scheduled PRBs assigned to / associated with each TCI state. When the UE is configured with the higher-level parameter phaseTrackingRS (phase tracking reference signal) in DMRS-DownlinkConfig (DMRS downlink configuration), - The higher-layer parameters timeDensity (time density) and frequencyDensity (frequency density) in PTRS-DownlinkConfig (PTRS downlink configuration) are, as shown in Table 5.1.6.3-1 and Table 5.1.6.3-2 respectively, the thresholds ptrs-MCS i (i = 1, 2, 3) and N RB,i (i = 0, 1). - If one or both of the additional higher layer parameters timeDensity and frequencyDensity are set, and the RNTI is equal to MCS-C-RNTI, C-RNTI, or CS-RNTI, the UE shall assume that the antenna port presence and pattern of the PT-RS are a function of the scheduled MCS of the corresponding codeword and the scheduled PRBs of one TCI state of the corresponding bandwidth part as shown in Tables 5.1.6.3-1 and 5.1.6.3-2. - If the higher layer parameter timeDensity provided by PTRS-DownlinkConfig is not set, the UE shall assume that L PT-RS = 1. - If the higher layer parameter frequencyDensity provided by PTRS-DownlinkConfig is not set, the UE shall assume that K PT-RS = 2. - Otherwise, if neither of the additional higher layer parameters timeDensity and frequencyDensity is set, and the RNTI is equal to MCS-C-RNTI, C-RNTI, or CS-RNTI, the UE shall assume that PT-RS is present when L PT-RS = 1, K PT-RS = 2, and shall assume that PT-RS is not present otherwise. - The scheduled MCS from Table 5.1.3.1-1 is less than 10, or - The scheduled MCS from Table 5.1.3.1-2 is less than 5, or - The scheduled MCS from Table 5.1.3.1-3 is less than 15, or - N RB is less than 3, (and when the UE is configured with single-DCI based M-TRP URLLC schemes 2a and 2b, N RB is the scheduled PRBs allocated / associated with one TCI state, otherwise N RB(which is the scheduled bandwidth), or - Otherwise, if the RNTI is equal to RA-RNTI, SI-RNTI, or P-RNTI, the UE should assume that the PT-RS does not exist. [Table 3]

[0081] In some embodiments, using the first option described above, Section 5.1.6.3 of the current technical specification 3GPP TS 38.214 can be updated as follows. 5.1.6.3 PT-RS Reception Procedure If the UE is configured with M-TRP URLLC schemes 2a and 2b based on a single DCI, (and / or if the UE is configured with multiple (e.g., two or three or four) TCI states at one TCI code point), the UE should assume the presence and pattern of the PT-RS antenna ports based on each part of the scheduled PRBs assigned to / associated with each TCI state. If the UE is configured with the higher-layer parameter phaseTrackingRS in DMRS-DownlinkConfig, - The higher-layer parameters timeDensity and frequencyDensity in PTRS-DownlinkConfig are, respectively, as shown in Table 5.1.6.3-1 and Table 5.1.6.3-2, the threshold ptrs-MCS i (i = 1, 2, 3) and N RB,i (i = 0, 1). - If one or both of the additional higher-layer parameters timeDensity and frequencyDensity are configured and the RNTI is equal to MCS-C-RNTI, C-RNTI, or CS-RNTI, the UE should assume that the PT-RS antenna port presence and pattern are those corresponding to the scheduled MCS and N of the corresponding codeword as shown in Table 5.1.6.3-1 and Table 5.1.6.3-2 RBshould be assumed to be the function, and when the UE is configured with M-TRP URLLC schemes 2a and 2b based on a single DCI (and / or when the UE is configured with multiple (e.g., 2 or 3 or 4) TCI states at one TCI code point, otherwise, N RB is the scheduled bandwidth), N RB is the scheduled PRB allocated / associated with one TCI state in the corresponding bandwidth part, - When the upper layer parameter timeDensity given by PTRS-DownlinkConfig is not configured, the UE should assume that L PT-RS = 1. - When the upper layer parameter frequencyDensity given by PTRS-DownlinkConfig is not configured, the UE should assume that K PT-RS = 2. - Otherwise, when neither the additional upper layer parameters timeDensity and frequencyDensity are configured and the RNTI is equal to MCS-C-RNTI, C-RNTI, or CS-RNTI, the UE should assume that PT-RS exists when L PT-RS = 1, K PT-RS = 2, and assume that PT-RS does not exist in the following cases. - The scheduled MCS from Table 5.1.3.1-1 is less than 10, or - The scheduled MCS from Table 5.1.3.1-2 is less than 5, or - The scheduled MCS from Table 5.1.3.1-3 is less than 15, or - The NRB is less than 3, (and when the UE is configured with M-TRP URLLC schemes 2a and 2b based on a single DCI, the NRB is the scheduled PRB allocated / associated with one TCI state, otherwise, the NRB is the scheduled bandwidth), or - Otherwise, if the RNTI is equal to the RA-RNTI, SI-RNTI, or P-RNTI, the UE should assume that there is no PT-RS.

Table 4

[0082] In some embodiments, using the first option described above, Section 7.4.1.2.2 of the current technical specification 3GPP TS 38.211 can be updated as follows. 7.4.1.2.2 Mapping to Physical Resources When the UE is configured with the M-TRP URLLC schemes 2a and 2b based on a single DCI (and / or when the UE is configured with multiple (e.g., two or three or four) TCI states at one TCI code point), the UE should assume that the phase-tracking reference signal only exists within the resource blocks assigned to / associated with each TCI state of the PDSCH. Otherwise, the UE should assume that the phase-tracking reference signal only exists within the resource blocks used for the PDSCH only when the procedures in [6, TS 38.214] indicate that the phase-tracking reference signal is being used. The UE should assume that the phase-tracking reference signal only exists within the resource blocks assigned to / associated with each TCI state of the PDSCH only when the procedures in [6, TS 38.214] indicate that the phase-tracking reference signal is being used. If present, the UE should assume that the PDSCH PT-RS is scaled by the factor β PT-RS,i to conform to the transmission power specified in Clause 4.1 of [6, TS 38.214] and is mapped to the resource element (k,l) p,μ as follows.

Equation

Equation

Table 5

[0083] As an alternative to the first option, in the second option for mapping PT-RS to resource subsets, the common value of the mapping parameters may be set for all resource subsets based on the number of resources within each resource subset. For example, the frequency density of PT-RS, the PT-RS resource offset, etc. within all resource subsets may be set in the same way. In particular, for schemes 2a / 2b, the PT-RS on the two parts of the scheduled PRB assigned / associated with the two TCI states can be made identical as much as possible. By using the common value of the mapping parameters for all resource subsets, the resource subsets can be associated with the TCI state for transmitting the same codeword of data 140, so that the communication performance between the network device 110 and the terminal device 120 can be improved.

[0084] As an example of the second option, the common value of the frequency density of PT-RS may be set for all resource subsets. In this way, the distribution of PT-RS in different resource subsets can be unified as much as possible. To determine this common value of the frequency density, the network device 110 or the terminal device 120 can determine the number of resources within each respective resource subset. For example, referring to FIG. 3, the number of resources (e.g., PRBs) (resource subset 310) assigned / associated with TCI state A is N RB_a , and the number of resources (e.g., PRBs) (resource subset 320) assigned / associated with TCI state B is N RB_b . Assume. Then, the network device 110 or the terminal device 120 can determine the maximum number among the number of resources within each respective resource subset. For example, in FIG. 3, max(N RB_a , N RB_b ) represents the maximum value of N RB_a and N RB_b can be determined.

[0085] Next, the network device 110 or the terminal device 120 can determine the common frequency density of PT-RS in all resource subsets based on the maximum number. For example, referring to FIG. 3, by replacing the parameter "N RB " in Table 5.1.6.3-2 defined in 3GPP specification TS 38.214 with max(N RB_a , N RB_b ), the common frequency density of PT-RS that can be applied to both resource subsets 310 and 320 can be determined. Therefore, in scheme 2a / 2b, the PT-RS frequency density is based on the larger of the two parts associated with the two TCI states, and the presence / density of PT-RS is the same for the two parts. By using the number of maximum resources within the resource subset, individual calculations of the frequency density of PT-RS based on the number of individual resources can be avoided.

[0086] As another example of the second option, the common value of the frequency density of PT-RS may be set for all resource subsets. In this way, the distribution of PT-RS in different resource subsets can be made as uniform as possible. To determine this common value of the frequency density, the network device 110 or the terminal device 120 can determine the number of resources within each resource subset. For example, referring to FIG. 3, the number of resources (e.g., PRBs) (resource subset 310) assigned / associated with TCI state A is N RB_a , and the number of resources (e.g., PRBs) (resource subset 320) assigned / associated with TCI state B is N RB_b . Assume. Then, the network device 110 or the terminal device 120 can determine the minimum number among the number of resources within each resource subset. For example, in FIG. 3, min(N RB_a , N RB_b ) represents the minimum value of N RB_a and N RB_b can be determined.

[0087] Next, the network device 110 or the terminal device 120 can determine the common frequency density of PT-RS in all resource subsets based on the minimum number. For example, referring to FIG. 3, by replacing the parameter "N RB " in Table 5.1.6.3-2 defined in 3GPP specification TS 38.214 with min(N RB_a , N RB_b ), the common frequency density of PT-RS that can be applied to both resource subsets 310 and 320 can be determined. Therefore, in scheme 2a / 2b, the PT-RS frequency density is based on the smaller of the two parts associated with the two TCI states, and the presence / density of PT-RS is the same for the two parts. By using the minimum number of resources within the resource subset, individual calculations of the frequency density of PT-RS based on the number of individual resources can be avoided.

[0088] Instead of determining the common frequency density of subsets 310 and 320, the network device 110 or the terminal device 120 can determine the PT-RS frequency density within each resource subset based on the number of resources within each resource subset. For example, referring to FIG. 3, based on Table 5.1.6.3-2 defined in 3GPP TS 38.214, by replacing the parameter "N RB " with "N RB_a ", the PT-RS presence / density for subset 310 is determined as d1, and by replacing the parameter "N RB " with "N RB_b ", the PT-RS presence / density for subset 320 can be determined as d2.

[0089] Next, the network device 110 or the terminal device 120 can determine a map based on the maximum frequency density among the frequency densities. In other words, for schemes 2a / 2b, the frequency density of PT-RS in all the scheduled PRBs for PDSCH is the same, and the density can be determined as max(d1, d2). In some embodiments, if the PT-RS exists for at least a part, the PT-RS exists in all the scheduled PRBs. For example, if the PTRS exists for one part and does not exist for another part, the PTRS must exist for both parts. By comparing the individually calculated frequency densities, it is possible to avoid comparing the number of individual resources within the resource subset.

[0090] As another example of the second option, a common value of the PT-RS resource offset may be set for a resource subset. In this way, the distribution of PT-RS in different resource subsets can be made as uniform as possible. To determine this common value of the PT-RS resource offset, the network device 110 or the terminal device 120 can determine the offset between the start resource for mapping and the resource with the lowest frequency in each resource subset based on the number of resources in each resource subset, the frequency density within each resource subset, and the identifier of the terminal device.

[0091] For example, referring to FIG. 3, assume that the number of resources (e.g., PRBs) (resource subset 310) assigned / associated with TCI state A is N RB_a and the number of resources (e.g., PRBs) (resource subset 320) assigned / associated with TCI state B is N RB_b . The frequency density in each resource subset can be determined as described above based on Table 5.1.6.3-2 defined in 3GPP TS 38.214. The identifier of the terminal device 120 is known to the network device 110 and the terminal device 120. Then, using the above formula (1) defined in 3GPP TS 38.211, the network device 110 and the terminal device 120 can determine the respective offsets (e.g., k RB_a ref and k RB_b ref ) for the resource subsets 310 and 320.

[0092] Then, the network device 110 or the terminal device 120 can determine the mapping of PT-RS for all resource subsets based on the minimum offset among the offsets. In other words, the minimum offset can be used as the common value of the PT-RS resource offsets for all resource subsets. For example, referring to FIG. 3, the PT-RS resource offsets in all scheduled PRBs of the PDSCH are the same, and the PT-RS resource offset can be determined as min(k RB_a ref ,k RB_b ref ). In this way, by comparing the offsets calculated for each resource offset using the existing formula (1), the common value of the PT-RS resource offset can be determined.

[0093] Instead of determining a common PT-RS resource offset value for the subset, the common value of the PT-RS resource offset may be based on the smallest of the resource subsets, i.e., the one with the smallest number of resources. For example, referring to FIG. 3, assume the number of resources (e.g., PRBs) (resource subset 310) assigned / associated with TCI state A is N RB_a , and the number of resources (e.g., PRBs) (resource subset 320) assigned / associated with TCI state B is N RB_b .

[0094] Next, the network device 110 or the terminal device 120 can determine the common value of the PT-RS resource offset based on the following formula (2). That is, for scheme 2a / 2b, the resource offsets of the two parts associated with the two TCI states are the same, and the value can be determined as follows.

Equation

[0095] In a third option of mapping PT-RS to a resource subset, the mapping of PT-RS to the resource subset can be determined based on the entire resource set (i.e., the scheduled bandwidth) indicated in the control information 135. In other words, the common value of the mapping parameter can be set for the resource subset based on the entire resource set, rather than the number of each resource within the resource subset. For example, for the iterative schemes 2a / 2b, the PT-RS settings (i.e., PT-RS presence / density / mapping) on two parts of the scheduled PRBs assigned / associated with two TCI states can be based on the entire scheduled bandwidth.

[0096] As an example of the third option, the network device 110 or the terminal device 120 can determine the common frequency density of PT-RS within the resource subset based on the number of resources within the resource set. For example, referring to FIG. 3, assume that the number of resources in the resource set 300 is N RB . Then, the common values of the frequency density of PT-RS in the resource subsets 310 and 320 can be determined based on N RB (e.g., according to Table 5.1.6.3-2 defined in 3GPP TS 38.214).

[0097] Then, the network device 110 or the terminal device 120 can map the PT-RS to the resource subsets in an order in which one resource subset follows another based on the common frequency density. In other words, for scheme 2a / 2b, the PT-RS mapping order is such that the PT-RS is mapped to a part of the scheduled PRBs assigned / associated with one TCI state and then to another part of the scheduled PRBs assigned / associated with another TCI state. For example, referring to FIG. 3, the mapping of the PT-RS is performed on the resource subset 310 and then on the resource subset 320. In this way, the distribution of the PT-RS in different resource subsets can be made as uniform as possible.

[0098] As another example of the third option, the network device 110 or the terminal device 120 can determine the common frequency density of the PT-RS within a resource subset based on the number of resources in the resource set multiplied by the number of resource subsets. In particular, the PT-RS frequency density is based on Table 5.1.6.3-2 defined in 3GPP TS 38.214, and for scheme 2a / 2b, N in the table RB is replaced by 2 * the number of scheduled PRBs (i.e., twice the number of scheduled PRBs). For example, referring to FIG. 3, since the resource set 300 is divided into two subsets, the common value of the frequency density of the PT-RS in the resource subsets 310 and 320 can be determined based on 2N RB This simplifies the calculation of the common value of the frequency density of the PT-RS without having to determine the number of individual resources within the resource subset.

[0099] As another example of the third option, the network device 110 or the terminal device 120 can determine the initial frequency density of the PT-RS based on the number of resources in the resource set. For example, referring to FIG. 3, the initial frequency density of the PT-RS can be determined based on N RB using Table 5.1.6.3-2 defined in 3GPP TS 38.214. Next, the network device 110 or the terminal device 120 can determine the mapping based on the minimum value between the initial frequency density multiplied by the number of resource subsets and 1 / 2.

[0100] In particular, for scheme 2a / 2b, the PT-RS frequency density is based on Table 5.1.6.3-2 defined in 3GPP TS 38.214, and the final density is min(1 / 2, 2 * density) or min(1, 2 * density). For example, referring to FIG. 3, if this value is less than 1 / 2 or 1, the common value of the PT-RS frequency density in the resource subsets 310 and 320 can be RB twice the value determined based on N, thereby preventing the PT-RS frequency density from becoming excessively high and avoiding potential interference caused by PT-RS transmission. In addition, in this way, the calculation of the common value of the PT-RS frequency density can be simplified without determining the number of individual resources in the resource subset.

[0101] As yet another example of the third option, for scheme 2a / 2b, the PT-RS frequency density can be based on a newly designed table that is different from Table 5.1.6.3-2 defined in 3GPP specification TS38.214. In this way, the PT-RS frequency density in the resource subset can be determined in any other appropriate way without being restricted by Table 5.1.6.3-2 defined in the 3GPP specification. For example, the new table can be shown as Table 1 below.

Table 6

[0102] Returning to FIG. 2, after determining the mapping to the resource subset of PT-RS, network device 110 and terminal device 120 can perform PT-RS transmission 230 therebetween. For example, when downlink PT-RS is transmitted between network device 110 and terminal device 120, for each TCI state, network device 110 transmits PT-RS to terminal device 120 within the resource subset associated with the TCI state according to the determined mapping. On the receiving side, terminal device 120 receives PT-RS from network device 110 within the resource subset associated with the TCI state according to the determined mapping.

[0103] Alternatively, when uplink PT-RS is transmitted between network device 110 and terminal device 120, for each TCI state, terminal device 120 transmits PT-RS to network device 110 within the resource subset associated with the TCI state according to the determined mapping. On the receiving side, network device 110 receives PT-RS from terminal device 120 within the resource subset associated with the TCI state according to the determined mapping.

[0104] FIG. 4 shows a flowchart of another exemplary method 400 according to some embodiments of the present disclosure. In some embodiments, method 400 can be implemented in a terminal device (e.g., terminal device 120 shown in FIG. 1). Further, or alternatively, method 400 may be implemented in other terminal devices not shown in FIG. 1. For the sake of discussion, method 400 will be described with reference to FIG. 1 as being executed by terminal device 120 without loss of generality.

[0105] In block 410, the terminal device receives, from the network device, control information indicating a resource set and a TCI state for communication between the terminal device and the network device. In block 420, the terminal device determines a resource subset associated with each TCI state, where each resource subset is a part in the frequency domain of the resource set. In block 430, the terminal device determines a mapping from the PT-RS to the resource subsets.

[0106] In some embodiments, determining the mapping includes determining, for each resource subset, a value of a mapping parameter, or determining a common value of the mapping parameter for the resource subsets.

[0107] In some embodiments, determining the mapping includes, for each of the resource subsets, determining a frequency density of the PT-RS based on the number of resources within the resource subset.

[0108] In some embodiments, determining the mapping further includes, for each of the resource subsets, determining an offset between a start resource for the mapping and a resource having the lowest frequency within the resource subset based on the number, the frequency density, and an identifier of the terminal device.

[0109] In some embodiments, determining the mapping includes determining the number of resources within each of the resource subsets, determining the maximum number among the numbers, and determining a common frequency density of the PT-RS within the resource subsets based on the maximum number.

[0110] In some embodiments, determining the mapping includes determining a frequency density of the PT-RS within each of the resource subsets based on the number of resources within each of the resource subsets, and determining the mapping based on the maximum frequency density among the frequency densities.

[0111] In some embodiments, determining the mapping further includes determining an offset between a start resource for the mapping and a resource having the lowest frequency within each resource subset based on the number, the frequency density, and the identifier of the terminal device, and determining the mapping based on the minimum offset among the offsets.

[0112] In some embodiments, determining the mapping includes determining a common frequency density of PT-RS within a resource subset based on the number of resources in the resource set, and mapping the PT-RS to the resource subsets in an order in which one resource subset follows another resource subset based on the common frequency density.

[0113] In some embodiments, determining the mapping includes determining a common frequency density of PT-RS within a resource subset based on the number of resources in the resource set multiplied by the number of resource subsets.

[0114] In some embodiments, determining the mapping includes determining an initial frequency density of PT-RS based on the number of resources in the resource set, and determining the mapping based on the minimum value between the initial frequency density multiplied by the number of resource subsets and 1 / 2.

[0115] FIG. 5 shows a flowchart of another exemplary method 500 according to some embodiments of the present disclosure. In some embodiments, method 500 can be implemented in a network device (e.g., network device 110 shown in FIG. 1). Further, or alternatively, method 500 may be implemented in other network devices not shown in FIG. 1. For the sake of discussion, method 500 is described with reference to FIG. 1 as being executed by network device 110 without loss of generality.

[0116] In block 510, the network device transmits to the terminal device control information indicating a resource set and a TCI state for communication between the terminal device and the network device. In block 520, the network device determines a resource subset associated with each TCI state, and each resource subset is a part in the frequency domain of the resource set. In block 530, the network device determines a mapping of the PT-RS to the resource subset.

[0117] In some embodiments, determining the mapping includes determining a value of a mapping parameter for each resource subset, or determining a common value of the mapping parameter for the resource subsets.

[0118] In some embodiments, determining the mapping includes determining, for each of the resource subsets, a frequency density of the PT-RS based on the number of resources within the resource subset.

[0119] In some embodiments, determining the mapping further includes determining, for each of the resource subsets, an offset between a start resource for the mapping and a resource having the lowest frequency within the resource subset based on the number, the frequency density, and an identifier of the terminal device.

[0120] In some embodiments, determining the mapping includes determining the number of resources within each of the resource subsets, determining the maximum number among the numbers, and determining a common frequency density of the PT-RS within the resource subsets based on the maximum number.

[0121] In some embodiments, determining the mapping includes determining the frequency density of the PT-RS within each resource subset based on the number of resources within each resource subset, and determining the mapping based on the maximum frequency density among the frequency densities.

[0122] In some embodiments, determining the mapping further includes determining an offset between a start resource for the mapping and the resource having the lowest frequency within each resource subset based on the number, the frequency density, and the identifier of the terminal device, and determining the mapping based on the minimum offset among the offsets.

[0123] In some embodiments, determining the mapping includes determining a common frequency density of the PT-RS within the resource subset based on the number of resources within the resource set, and mapping the PT-RS to the resource subsets in an order in which one resource subset follows another resource subset based on the common frequency density.

[0124] In some embodiments, determining the mapping includes determining a common frequency density of the PT-RS within the resource subset based on the number of resources within the resource set multiplied by the number of resource subsets.

[0125] In some embodiments, determining the mapping includes determining an initial frequency density of the PT-RS based on the number of resources within the resource set, and determining the mapping based on the minimum value between the initial frequency density multiplied by the number of resource subsets and 1 / 2.

[0126] FIG. 6 is a simplified block diagram of an apparatus 600 suitable for implementing some embodiments of the present disclosure. The apparatus 600 can be considered as another exemplary embodiment of the network apparatus 110 and the terminal apparatus 120 shown in FIG. 1. Therefore, the apparatus 600 can be implemented in the network apparatus 110 and the terminal apparatus 120, or at least partially as the network apparatus 110 and the terminal apparatus 120.

[0127] As shown, the apparatus 600 includes a processor 610, a memory 620 coupled to the processor 610, a suitable transmitter (TX) and receiver (RX) 640 coupled to the processor 610, and a communication interface coupled to the TX / RX 640. The memory 620 stores at least a part of a program 630. The TX / RX 640 is for bidirectional communication. The TX / RX 640 has at least one antenna to facilitate communication, but the access nodes mentioned in this specification can actually have a plurality of antennas. The communication interface can represent any interface required for communication with other network elements, such as, for example, an X2 interface for bidirectional communication between gNBs or eNBs, an S1 interface for communication between a mobility management entity (MME) / serving gateway (S-GW) and a gNB or eNB, a 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 apparatus.

[0128] Program 630 is assumed to include program instructions, and when these program instructions are executed by the associated processor 610, it enables apparatus 600 to operate in accordance with the embodiments of the present disclosure described with reference to either one of FIGS. 4 and 5 in the text. The embodiments in the text can be realized by computer software executable by processor 610 of apparatus 600, or by hardware, or by a combination of software and hardware. Processor 610 can be configured to implement various embodiments of the present disclosure. Further, the combination of processor 610 and memory 620 can form a processing device 650 suitable for implementing various embodiments of the present disclosure.

[0129] As a non-limiting example, memory 620 can be of any type suitable for a local technology network, and can be realized using any appropriate data storage technology, such as a non-transitory computer-readable storage medium, a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, a fixed memory, and a removable memory. Although only one memory 620 is shown within apparatus 600, there may be several physically different memory modules within apparatus 600. As a non-limiting example, processor 610 can be of any type suitable for a local technology network, and can include a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP), and a plurality of processors based on a multi-core processor architecture. Apparatus 600 can have a specific-purpose integrated circuit chip that is temporally dependent on a clock that synchronizes a plurality of processors, for example, a main processor.

[0130] The components included in the devices and / or equipment of the present disclosure can be realized in various ways including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be realized using software and / or firmware (e.g., machine-executable instructions stored in a storage medium). In addition to or instead of the machine-executable instructions, some or all of the units within the device and / or equipment may be realized, at least in part, by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that can be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0131] Generally, the various embodiments of the present disclosure can be realized by hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be realized in hardware, and other aspects may be realized by firmware or software executable by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are illustrated and described using block diagrams, flowcharts, or some other pictorial representation, as a non-limiting example, it should be understood that the blocks, devices, systems, techniques, or methods described herein can be implemented by hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or any combination thereof.

[0132] The present disclosure also 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., instructions included in program modules) that are executed within an apparatus on a target physical processor or virtual processor to perform any one of the processes or methods described above with reference to FIGS. 4 to 5. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functions of the program modules can be combined or divided among the program modules as needed in various embodiments. The machine-executable instructions of the program modules can be executed within a local or distributed apparatus. In a distributed apparatus, the program modules may be disposed in both a local storage medium and a remote storage medium.

[0133] The program code for executing the method of the present disclosure can be described in any combination of multiple programming languages. This program code is provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing apparatus, and when executed by the processor or controller, realizes the functions / operations specified in the flowchart and / or block diagram with the program code. The program code can be executed entirely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0134] The above program code can be implemented on a machine-readable medium, and the machine-readable medium can be any tangible medium that can contain or store a program used by or in combination with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium can include an electrical connection having one or more wires, a portable computer floppy 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 foregoing.

[0135] Also, although the operations are described in a particular order, it should not be understood that this requires the operations to be performed in the particular order shown or in a sequential order, or that all of the shown operations be performed, to obtain the desired result. In some cases, multitasking or parallel processing may be advantageous. Similarly, although details of some specific embodiments are included in the above discussion, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features specific to particular embodiments. Some features described in the context of individual embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may be implemented separately in multiple embodiments, or in any suitable subcombination.

[0136] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. More precisely, the specific features and acts described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A communication method for a terminal device, comprising: receiving, from a network device, control information indicating a resource set for communication between the terminal device and the network device and a plurality of transmission configuration indication (TCI) states; determining a mapping of a phase tracking reference signal (PT-RS) to a resource element based on a physical resource block (PRB) associated with each of the plurality of TCI states; wherein a frequency density of the PT-RS is determined based on a number of the PRBs associated with each of the plurality of TCI states. A communication method.

2. A communication method for a network device, comprising: transmitting, to a terminal device, control information indicating a resource set for communication between the terminal device and the network device and a plurality of transmission configuration indication (TCI) states; determining a mapping of a phase tracking reference signal (PT-RS) to a resource element based on a physical resource block (PRB) associated with each of the plurality of TCI states; wherein a frequency density of the PT-RS is determined based on a number of the PRBs associated with each of the plurality of TCI states. A communication method.

3. A terminal device, comprising: means for receiving, from a network device, control information indicating a resource set for communication between the terminal device and the network device and a plurality of transmission configuration indication (TCI) states; means for determining a mapping of a phase tracking reference signal (PT-RS) to a resource element based on a physical resource block (PRB) associated with each of the plurality of TCI states, wherein a frequency density of the PT-RS is determined based on a number of the PRBs associated with each of the plurality of TCI states. A terminal device.

4. A network device, comprising: means for transmitting, to a terminal device, control information indicating a resource set for communication between the terminal device and the network device and a plurality of transmission configuration indication (TCI) states; means for determining a mapping of a phase tracking reference signal (PT-RS) to a resource element based on a physical resource block (PRB) associated with each of the plurality of TCI states, wherein a frequency density of the PT-RS is determined based on a number of the PRBs associated with each of the plurality of TCI states. A network device.

Images