EP4666493A1 - Dmrs-ptrs association - Google Patents

Abstract

Embodiments of the present disclosure relate to methods and apparatus for DMRS port and PTRS port for SFN based PUSCH. A terminal device receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device. In this way, the terminal device can use a DMRS port and a PTRS port associated with the DMRS port to transmit the uplink signal in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

Description

DMRS-PTRS ASSOCIATION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority from, and the benefit of, Finland application No. 20235188, filed February 17, 2023, the contents of which is hereby included by reference in its entirety.

FIELD

[0002] Various example embodiments relate to the field of telecommunication and in particular, to a method, device, apparatus and computer readable storage medium for demodulation reference signal (DMRS)- phase tracking reference signal (PTRS) association for, especially, single frequency network (SFN) based uplink transmission.

BACKGROUND

[0003] In the communications area, there is a constant evolution ongoing in order to provide efficient and reliable solutions for utilizing wireless communication networks. Each new generation has it owns technical challenges for handling the different situations and processes that are needed to connect and serve devices connected to the wireless network. In 5G NR, it was proposed to support simultaneous multi-panel UL transmission with at least two panels. In comparison to single downlink control information (S-DCI) based Rel-17 time division multiplexing (TDM) repetition scheme, both S-DCI and multi (M)-DCI based simultaneous uplink multi-panel physical uplink channel (PUSCH) schemes will be investigated in Rel-18, targeting to enhance throughput and reliability with reduced latency.

[0004] Traditionally, uplink demodulation reference signal (DMRS) and phase tracking reference signal (PTRS) are reference signals associated with PUSCH. The DMRS is a special type of physical layer signal which functions as a reference signal for decoding PUSCH and is used for channel estimation as part of coherent demodulation of PUSCH. To compensate for the common phase error (CPE), 3GPP 5G NR introduced PTRS. PTRS is used mainly to estimate and minimize the effect of CPE on system performance. In DCI, there is a PTRS-DMRS association field which it is used to link PTRS port to DMRS port. However, the existing PTRS-DMRS association cannot be applied in either S-DCI or multi (M)-DCI based simultaneous uplink multi-panel PUSCH schemes, and thus the association of PTRS port and DMRS port needs to be further researched.

SUMMARY

[0005] In general, example embodiments of the present disclosure provide a solution for DMRS port and PTRS port for SFN based PUSHC.

[0006] In a first aspect, there is provided a terminal device. The terminal device comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS- DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

[0007] In a second aspect, there is provided a network device. The terminal device comprises at least one processor; at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0008] In a third aspect, there is provided a method implemented at a terminal device. The method comprises receiving, by the terminal device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication from a network device,, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmitting, by the terminal device, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two and more antenna panels of the terminal device, based on the PTRS-DMRS association indication.

[0009] In a fourth aspect, there is provided a method implemented at a network device. The method comprises transmitting, by the network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receiving, by the network device, an uplink signal from a terminal device in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0010] In a fifth aspect, there is provided an apparatus comprising means for receiving a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication from a network device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and means for transmitting an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two and more antenna panels of the apparatus, based on the PTRS-DMRS association indication.

[0011] In an sixth aspect, there is provided an apparatus comprising means for transmitting a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and means for receiving an uplink signal from a terminal device in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0012] In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication from a network device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmitting an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two and more antenna panels of the apparatus, based on the PTRS-DMRS association indication.

[0013] In an eighth aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: transmitting a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS- DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receiving an uplink signal from a terminal device in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0014] In a ninth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the apparatus.

[0015] In a tenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to: transmit a phasetracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0016] In an eleventh aspect, there is provided a terminal device. The terminal device comprises one or more transceivers; and one or more processors communicatively coupled to the one or more transceivers, wherein the one or more processors are configured to cause the terminal device to: receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS- DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

[0017] In a twelfth aspect, there is provided a network device. The network device comprises one or more transceivers; and one or more processors communicatively coupled to the one or more transceivers, wherein the one or more processors are configured to cause the network device to: transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS- DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0018] In a thirteenth aspect, there is provided a terminal device. The terminal device comprises receiving circuitry configured to receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmitting circuitry configured to transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

[0019] In a fourteenth aspect, there is provided a network device. The network device comprises transmitting circuitry configured to transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receiving circuitry configured to receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[0020] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0022] Fig. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

[0023] Fig. 2 illustrates an example signaling flow illustrating a process for DMRS-PTRS port association for SFN based PUSCH according to some embodiments of the present disclosure;

[0024] Fig. 3 illustrates an example schematic diagram of uplink sounding reference signal (SRS) resource set configurations for SFN based simultaneous multi-panel PUSCH transmission with two layers according to some embodiments of the present disclosure;

[0025] Fig. 4 illustrates another example schematic diagram of uplink sounding reference signal (SRS) resource set configurations for SFN based simultaneous multi-panel PUSCH transmission with four layers according to some embodiments of the present disclosure;

[0026] Fig. 5 illustrates an example schematic diagram of PTRS-DMRS association for UL PTRS port 0 or for the actual UL PTRS port according to some embodiments of the present disclosure;

[0027] Fig. 6 illustrates an example flowchart of a method implemented at a terminal device according to some embodiments of the present disclosure;

[0028] Fig. 7 illustrates an example flowchart of a method implemented at a network device according to some other embodiments of the present disclosure;

[0029] Fig. 8 illustrates an example simplified block diagram of an apparatus that is suitable for implementing embodiments of the present disclosure; and

[0030] FIG. 9 illustrates an example block diagram of an example computer readable medium in accordance with some embodiments of the present disclosure.

[0031] Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

[0032] Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

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

[0034] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0035] It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including”, when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/ or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0037] As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable):

(i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit(s) and or processor(s), such as a microprocessor s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0038] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0039] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as long term evolution (LTE), LTE-Advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), narrow band internet of things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the future fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0040] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

[0041] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0042] Rel-15 specification enables user equipment (UE) to be configured either codebook or non-codebook based physical uplink shared channel (PUSCH) transmission with two uplink (UL) sounding reference signal (SRS) resource sets. In other words, based on this configuration, the UE shall transmit PUSCH up to rank 4 with single transmitting (TX) antenna panel to single TRP. This mode is referred as Rel-15 UL TX mode.

[0043] For wireless communication systems (e.g. LTE and NR), local oscillator (LO) is an essential component for shifting carrier frequency up- or downwards in transceivers. The quality of LO is defined by phase-noise of the LO. Depending on the combination of scheduled/configured modulation order and bandwidth for data and/or control information transmission, the impact of phase-noise can be negative to a system performance without any specification support for phase noise compensation, especially at high carrier frequencies, e.g. for above 52.6GHz.

[0044] For Rel-15, a physical layer provides a support for phase-noise compensation by specifying a phase tracking reference signal (PTRS) for UL and DL with orthogonal frequency division multiplexing (OFDM) as well as UL single carrier discrete-flourier- transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) waveforms. The PTRS is used for tracking the phase of the local oscillator at the receiver and transmitter. This may enable suppression of phase noise and common phase error, particularly important at high carrier frequencies such as millimeter wave.

[0045] For UL, depending on reported capability, UE can be scheduled with one or two PTRS port(s). When UE has capability for non-/partial coherent codebook based PUSCH transmission, two PT-RS ports can be used for the UE with two local oscillators. Typically, this corresponds to the case of UE equipped with two or more UL TX antenna panels. When UE has reported the capability of supporting full-coherent UL transmission, only a single PTRS port is used.

[0046] For non-codebook based PUSCH transmission, the actual number of a transmitted UL PTRS port(s) is determined based on SRS resource indicators (SRIs). UE may be configured with the PTRS port index for each configured SRS resource by the higher layer parameter ptrs-Portlndex configured by SRS-Config. If the PTRS port index associated with different SRIs are the same, the corresponding UL DM-RS ports are associated to the one UL PT-RS port.

[0047] Downlink control information DCI format 0 1 or format 0 2 defines PTRS-DMRS association field which it is used to link a PTRS to a UL DMRS. This allows the pair of reference signals to be used in combination, i.e. channel estimates derived from both and interpolated between them. If transform precoding is enabled or if the configured maximum uplink rank is 1 (based upon the maxRank information element), then the PTRS-DMRS association field is not required and is excluded from the DCI.

[0048] When only a single DMRS is configured, the PTRS is linked by default to that specific DMRS. Otherwise, the PTRS-DMRS association field in DCI occupies 2 bits and these bits are used to identify either 1st or 2nd DMRS. Table 1 shows an example of PTRS- DMRS association field.

Table 1 PTRS-DMRS association or Second PTRS-DMRS association for UL PTRS port 0

[0049] When the UE transmits a single PTRS, DCI indicates one of four different DMRSs and indicated DMRS antenna port is associated with the single PTRS antenna port. When the UE transmits two PTRS antenna ports, MSB and LSB of DCI field indicate one of the DMRS antenna ports for PTRS antenna port 0 or 1.

[0050] For codebook or non-codebook based UL transmission, the association between UL PTRS port(s) and DMRS port(s) is signaled by PTRS-DMRS association field(s) in DCI format 0 1 and DCI format 0 2, as shown in Table 1.

[0051] In Rel-17, there is a single downlink control information indicator (S-DCI) for timedivision multiplexing (TDM) multi-transmission-reception point (M-TRP) physical uplink shared channel (PUSCH) repetition and antenna panel selection. Rel-17 was specified to enhance reliability of uplink transmission in the context of multi-TRP scenario. UE is configured with two different UL SRS resource sets with a followUnifiedTCIstateSRS information element to follow two different DL/or joint DL and UL/UL transmission configuration indication (TCI) states associated as the spatial source.

[0052] Based on the Rel-17 capability set index reporting, a network can be aware of the UE antenna panel (including information on the number of UL SRS antenna ports) specific transmission capability of UL SRS codebook-based transmission into a certain spatial UL direction. Based on this information, the network can trigger transmission of two different UL SRS resource sets with the usage of codebook to obtain TRP-specific transmit precoding matrix identity (TPMI) hypotheses (i.e., determine pre-coder index and rank selection) antenna panel specifically for PUSCH transmissions.

[0053] Based on obtained TRP-specific TPMI and SRI information, the network can trigger non-simultaneous TRP-specific Rel-17 PUSCH transmission by indicating via DCL a codepoint for a single SRS resource set indicator, in which 2 -bits, and thereby 4 values, are reserved, when two SRS resource sets configured with usage codebook or non-codebook, and otherwise O-bit, the first value out of the four possible values of the DCI codepoint may be used to indicate which of the two SRS resource indicators (SRIs), the first or the second, is used to enable dynamic switching between a single TRP (either TRP1 or either TRP2) PUSCH transmission in time division multiplexing (TDM) manner. The other remaining two bits may be used to enable multi-TRP PUSCH transmission between TRP1 and TRP2 in TDM manner with repetition either cyclical or sequential mapping configured via radio resource control (RRC)for mapping two SRIs to PUSCH repetitions. Moreover, for codebook based transmission, the DCI includes two separate codepoint fields for SRIs and two precoding information and number of transmission layers fields. The first field indicates the number of transmission layers, whereas the second field does not. For non-codebook based transmission, the DCI may comprise two SRI codepoint fields, where the first one indicates the transmission layers and second does not. Based on the received S-DCI, the terminal device may then transmit the PUSCH transmission using the multiple antenna panels (only one panel at the time). This mode is referred as Rel-17 UL TX mode.

[0054] Rel-17 defines a way to associate PTRS and DMRS antenna ports to different TRPs according to configured maxRank. A first PTRS-DMRS association field in DCI is applied shown in Table 2 as follows. The first PTRS-DMRS association field may be set as 2 bits, where Table 2 and 3 are used to indicate the association between PTRS port(s) and DMRS port(s) when one PT-RS port and two PT-RS ports are configured by maxNrofPorts in PTRS- UplinkConfig respectively, and the DMRS ports are indicated by the antenna ports field. When the SRS resource set indicator field is present and maxRank>2, this field indicates the association between PTRS port(s) and DMRS port(s) corresponding to SRS resource indicator field and/or Precoding information and number of layers field according to Table 2 and 3. When the SRS resource set indicator field is present and equals "10" and "11" and maxRank=2, the MSB of this field indicates the association between PTRS port(s) and DMRS port(s) corresponding to SRS resource indicator and/or precoding information and number of layers field, and the LSB of this field indicates the association between PTRS port(s) and DMRS port(s) corresponding to Second SRS resource indicator field and/or Second Precoding information field, according to Table 2.

Table 2 PTRS-DMRS association for UL PTRS 0

[0055] When the maxRank of scheduled PUSCH>2, the second PTRS-DMRS association field in DCI, shown in Table 3, is applied in conjunction of the first PTRS-DMRS association field as follows: a second PTRS-DMRS association-2 bits if PTRS-DMRS association field and SRS resource set indicator field are present and maxRank>2; 0 bit otherwise.

[0056] Table 2 and 3 are used to indicate the association between PTRS port(s) and DMRS port(s) corresponding to Second SRS resource indicator field and/or Second precoding information field when one PT-RS port and two PT-RS ports are configured by maxNrofPorts in PTRS-UplinkConfig respectively, and the DMRS ports are indicated by the Antenna ports field.

Table 3 PTRS-DMRS association or Second PTRS-DMRS association for UL PTRS 0 and

UL PTRS 1

[0057] As shown in Table 2, two bits, of the MSB and LSB of the PTRS-DMRS association field, indicate scheduled DMRS ports corresponding different SRS resource indicator fields and/or precoding information and number of layers fields when there is one PTRS port. Furthermore, when PTRS-DMRS association field and SRS resource set indicator field are present and maxRank>2, the second PTRS-DMRS association field is used.

[0058] In comparison to single (S)-DCI based Rel-17 TDM repetition scheme, Rel-18 will specify support for both S-DCI and multi (M)-DCI based simultaneous uplink multi-panel PUSCH schemes with SDM and SFN, targeting to enhance throughput and reliability with reduced latency.

[0059] For S-DCI, a network is assumed to have a centralized scheduler with an ideal backhaul between multiple TRPs, whereas for M-DCI distributed scheduler with non-ideal backhaul is assumed. In SDM-based scheme, different layers/DMRS ports of one PUSCH are separately precoded and transmitted from different UE panels simultaneously. In SFN- based transmission scheme, all of the same layers/DMRS ports of one PUSCH transmission occasion are transmitted from two different UE panels simultaneously.

[0060] In addition, it has been agreed that the Rel-18 UE can be configured use singlefrequency network (SFN) or spatial division multiplexing (SDM) transmission mode. In an SDM scheme, different PUSCH layers and DMRS antenna ports of one codeword are separately pre-coded and transmitted from different UE antenna panels simultaneously; in an SFN-based transmission scheme, the same PUSCH layers and DMRS antenna ports are transmitted simultaneously with two different pre-coders via two different UE antenna panels associated with different TCI states

[0061] Thus, for single-DCI based ST x MP PUSCH SDM scheme, it may support the layer combinations of { 1+1, 1+2, 2+1 and 2+2} for single code word (CW) case. The DMRS port indication for SDM scheme single-DCI based ST x MP transmission is also supported, where the DMRS antenna ports associated with two TPMI/SRI fields can be in the same or different CDM groups.

[0062] Therefore, Rel-18 specification provides support for different simultaneous multipanel PUSCH transmission modes, i.e. SDM. Furthermore, the Rel-18 provides also support for legacy PUSCH transmission modes, e.g. Rel-15 single antenna panel to single TRP, Rel- 17 TDM based single antenna panel to multi-TRP, as discussed in previous section.

[0063] However, existing DMRS-PTRS association cannot be applied in Rel-18 due to the above difference and an ambiguity remains for the Rel-18 UE how to interpret correctly the PTRS-DMRS association for SFN based simultaneous multi-panel PUSCH transmission (i.e., how to distinguish SFN based operation with respect to legacy operation and SDM based operation). In other words, the PTRS-DMRS association for SFN based simultaneous multi-panel PUSCH transmission is not resolved.

[0064] According to embodiments of the present disclosure, there is providing a solution for DMRS-PTRS port association for SFN based PUSCH. In this solution, a terminal device receives, from a network device, a phase-tracking reference signal (PTRS)- demodulation reference signal (DMRS) association indication. The terminal device transmits, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device. The PTRS-DMRS association indication comprises a PTRS- DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port. The terminal device reports an indication to a network device based on the measurement value, wherein the indication indicates at least one uplink transmission scheme that can be used.

[0065] As such, with the embodiments, the PTRS-DMRS association may indicated to the terminal device in a flexible and efficient way, and then the terminal may determine a DMRS port and a corresponding PTRS port for the SFN based simultaneous multi-panel PUSCH transmission. Thus, the solution proposed herein may enable the SFN based simultaneous multi-panel PUSCH transmission.

[0066] Principle and embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, it is to be noted that these embodiments are illustrated as examples and not intended to limit scope of the present application in any way.

[0067] Reference is first made to Fig. 1, which illustrates an example communication system 100 in which embodiments of the present disclosure may be implemented. As illustrated in Fig. 1, the system 100 includes two transmission and reception points (TRPs), such as TRPs 120, 130. The TRPs 120, 130 may each have one respective group of antenna ports. In other words, the TRPs 120, 130 may be associated with or function as two respective network devices, and thus sometimes they can be also referred to as network device 120 and network device 130 in the present disclosure. For clarity purposes, TRP 120 may be also referred to a first TRP, and TRP 130 may be also referred to a second TRP.

[0068] The TRPs 120, 130 may each operate using different frequency bands in both DL and UL. In communication systems, “UL” refers to a communication link in a direction from a terminal device to a network device, and “DL” refers to a communication link in a direction from the network device to the terminal device.

[0069] The system 100 also includes one or more terminal devices, such as terminal device 110. The terminal device 110 are capable of connecting, for example wirelessly, and communicating in an UL and DL with either or both of the TRPs 120, 130 depending on location of the terminal devices in the cells of the TRPs 120, 130. The terminal device 110 may be configured to be communicated with network via one or more TRPs, for example 2 TRPs. The two TRPs may be located within the same cell (intra-cell TRP) or within different cells (inter-cell TRP).

[0070] The terminal device 110 may be a MP-UE comprising a plurality of panels. From a wireless communication perspective, a MP-UE may comprise any device having a plurality of antenna groups configured as a panel. The MP-UE may provide flexibility in selecting antennas for wireless communication. In an aspect, although multiple panels of the MP-UE may be active, one panel may be selected for uplink transmission using a single beam. In other aspects, multiple beams may be transmitted simultaneously from multiple panels.

[0071] The terminal device 110 in Fig. 1 may comprise a plurality of panels, such as a first panel 111, a second panel 112, and additional optional panels (not shown) if necessary. In general, a panel may be a component of UE that includes one or more antenna group. The antenna group may comprise one or more antennas, antenna elements and/or antenna arrays. Each panel may operate independently to some extent. For example, each panel may be individually activated or deactivated. The activated panel may be used for transmission and/or reception, while the disabled panel may not be used for transmission and/or reception. The panels may be elements of an antenna group that independently control beams. For example, within the panel, one beam may be selected and used for UL transmission. In addition, multiple panels may be used for UL transmission, and multiple beams (each beam selected per panel) may be used for UL transmission across different panels.

[0072] It is to be understood that in Fig. 1, the number of network devices, terminal devices is only for the purpose of illustration without suggesting any limitations. Moreover, the number of panels of a terminal device is also given only for the purpose of illustration. The system 100 may include any suitable number of network devices and terminal devices and a terminal device may include any suitable number of panels, as long as the number could be adapted for implementing embodiments of the present disclosure.

[0073] Communications in the communication system 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the third generation (3G), the fourth generation (4G) and the fifth generation (5G) or beyond, wireless local network communication protocols such as institute for electrical and electronics engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple-input multiple-output (MIMO), orthogonal frequency division multiple (OFDM), discrete flourier transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

[0074] As illustrated in Fig. 1 a terminal device 110 may receive, from a network device, such as any of TRP 120, 130 a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication. The terminal device 110 transmits, based on the PTRS-DMRS association indication, an uplink signal to the network device such as any of TRP 120, 130 in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device. The PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port. The terminal device 100 reports an indication to a network device such as any of TRP 120, 130 based on the measurement value, wherein the indication indicates at least one uplink transmission scheme that can be used.

[0075] Reference is now made to Fig. 2, which shows an example of a process 200 for DMRS-PTRS port association for SFN based PUSCH according to some embodiments of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to Fig. 1. The network device 120 and the terminal device 110 may be involved in the process 200 for the purpose of illustration.

[0076] In the process 200, a terminal device 110 receives 202, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication. The PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port. In order to facilitate the terminal device to transmit an uplink signal, the network device 120 needs to send information about the PTRS port and DMRS port to the terminal device 110.

[0077] After obtaining the PTRS-DMRS association indication, the terminal device may transmit 204, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device. Therefore, the network device can receive the an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port. The PTRS-DMRS association indication may dynamic indicate uplink PTRS-DMRS antenna port association for SFN based simultaneous multi-panel PUSCH transmission.

[0078] In some embodiments, the first part of the PTRS-DMRS association field is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field. The second part of the PTRS-DMRS association field is configured to indicate a scheduled DMRS port sharing a PTRS port. For example, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[0079] In order to dynamic indicate uplink PTRS-DMRS antenna port association for SFN based simultaneous multi-panel PUSCH transmission, the PTRS-DMRS association indication can be configure using for example a signal DMRS-PTRS association field, which is also called Solution A hereinafter.

Solution A.

[0080] In this solution, when the UE scheduled with SFN based simultaneous multi-panel PUSCH with DCI, the PTRS-DMRS association field in scheduling DCI indicates only (independent of number of layers) the association between PTRS antenna port 0/1 (or 0/1/. . . ./port N) and scheduled DMRS antenna port(s) corresponding to both first and second SRS resource indicator and/or both first and second precoding information and number of layers.

[0081] For example, the PTRS-DMRS association field indicates the following information: most significant bit (MSB) indicates: k-th scheduled UL DMRS antenna port; least significant bit (LSB) indicates: n-th indicated PTRS antenna port out of N different configured by RRC or activated PTRS antenna ports, where MAC level signaling, e.g. medium access control (MAC) control element (CE), is used to activate and overwrite PTRS- DMRS association table with activated PTRS antenna ports.

[0082] When the PTRS-DMRS association field indicates above information, i.e., combination of MSB and LSB and SFN transmission is scheduled, the UE shall apply association between k-th scheduled DMRS antenna port and n-th indicated PTRS antenna port when transmitting UL DMRS and PTRS resource with SFN based simultaneous multipanel transmission by using both first SRI and second SRI and/or both first and second precoding information and number of layers.

[0083] In some example, the PTRS-DMRS association indication may comprise two PTRS- DMRS association fields, i.e., it comprises another PTRS-DMRS association field. In such a case, the UE shall ignore information associated with the another PTRS-DMRS association field (independent of indicated number of layers) which means, the terminal device will still interpret only one of the two PTRS-DMRS association fields, for example a first PTRS- DMRS association field.

[0084] In some embodiment, the PTRS-DMRS association indication may comprise another PTRS-DMRS association field and the another PTRS-DMRS association field may has a same structure as the PTRS-DMRS association field. For example, another PTRS- DMRS association field has the most significant bit (MSB) and least significant bit (LSB), wherein the MSB indicates k-th scheduled UL DMRS antenna port, and the LSB indicates: n-th indicated PTRS antenna port out of N different configured by RRC or activated PTRS antenna ports.

[0085] The two PTRS-DMRS association field may be used for different scenarios. For example, a first PTRS-DMRS association field is used for a lower number of layers associated with PUSCH and a second PTRS-DMRS association field is used for a higher number of layers associated with PUSCH.

[0086] In some embodiments, the network device 120 may notify the terminal device of the layer number for example, in a precoding information and number of layers field. Therefore, the network device 120 determines 206 a number of layers for the terminal device 110 to transmit the uplink signal in the SFN manner, and transmits 208 a layer number indication indicative of the number of layers to the terminal device 110. Then, the terminal device 110 may obtain a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner from the network device 120. Moreover, the network device 120 selects 210, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port. Then, the PTRS-DMRS association indication may be contained in the selected PTRS-DMRS association field and sent to the terminal device.

[0087] After receiving the PTRS-DMRS association indication, the terminal device 110 may select 212, based on the number of layers and a predetermined layer number threshold in 206, the one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port .

[0088] The terminal device 110 and the network device 120 may determine the total number of layers used by them. For example, the total number of layers can be comprised in DCI. Additionally or alternatively, the predetermined layer number threshold may be based on the total number of layers.

[0089] In some embodiments, when the number of layers is not higher than the predetermined layer number threshold, a first PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port. When the number of layers is higher than the predetermined layer number threshold, a second PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port. Additionally, in both the first and second PTRS-DMRS association fields, the first part comprises one or more most significant bits (MSB) and the second part comprises one or more least significant bits (LSB) and they may be used in a similar way. In the present disclosure, such a solution may also be called as Solution B, which will further described herein after.

Solution B .

[0090] In this solution, when the UE scheduled with SFN based simultaneous multi-panel PUSCH with L-layers via DCI, the first PTRS-DMRS or second PTRS-DMRS association field in scheduling DCI indicates only (independent of number of layers) the association between PTRS antenna port 0/1 (or 0/1/. .. ./port N) and scheduled DMRS antenna port(s) corresponding to both first and second SRS resource indicator and/or both first and second precoding information and number of layers.

[0091] When indicated PUSCH layers^L/2, the first PTRS-DMRS association field may be used to indicate the following information:

■ The most significant bit (MSB) indicates: k-th, scheduled UL DMRS antenna port sharing indicated n-th PTRS antenna port, where kU L/2,

■ The least significant bit (LSB) indicates: n-th indicated PTRS antenna port out of N different configured by RRC or activated PTRS antenna ports, where MAC level signaling, e.g. MAC CE, is used to activate and overwrite PTRS-DMRS association table with activated PTRS antenna ports.

[0092] When the first PTRS-DMRS association field indicates above information, i.e., combination of MSB and LSB and SFN transmission is scheduled, the UE shall apply the association between k-th scheduled DMRS antenna port and n-th indicated PTRS antenna port as indicated in the first PTRS-DMRS association field, when transmitting UL DMRS and PTRS resource with SFN based simultaneous multi-panel transmission. In the transmission, the terminal device may use both first SRI and second SRI and/or both first and second precoding information and number of layers. In this case, the UE shall ignore information associated with the another PTRS-DMRS association field (independent of indicated number of layers) and interpret only the most significant bit (MSB) and least significant bit (LSB) of the PTRS-DMRS association field.

[0093] On the other hand, when indicated PUSCH layers> L/2, the second PTRS-DMRS association field indicates the following information:

■ The most significant bit (MSB) indicates: j-th, where j>L/2, scheduled UL DMRS antenna port sharing indicated n-th PTRS antenna port;

■ The least significant bit (LSB) indicates: n-th indicated PTRS antenna port out of N different configured by RRC or activated PTRS antenna ports, where MAC level signaling, e.g. MAC CE, is used to activate and overwrite PTRS-DMRS association table with activated PTRS antenna ports.

[0094] When the second PTRS-DMRS association field indicates above information, i.e., combination of MSB and LSB and SFN transmission is scheduled, the UE shall apply association between j-th scheduled DMRS antenna port and n-th indicated PTRS antenna port when transmitting UL DMRS and PTRS resource with SFN based simultaneous multipanel transmission. In the transmission, the terminal device may use both first SRI and second SRI and/or both first and second precoding information and number of layers. In this case, the UE shall ignore information associated with the PTRS-DMRS association field (independent of indicated number of layers) and interpret only the most significant bit (MSB) and least significant bit (LSB) of the another PTRS-DMRS association field.

[0095] In some embodiments, the PTRS-DMRS association indication can be configured with another solution different from Solutions A and B, Which may be called as Solution C.

Solution C

[0096] In this solution, when the UE scheduled with SFN based simultaneous multi-panel PUSCH with DCI, the indication is done via the PTRS-DMRS association field and another PTRS-DMRS association field as follows: the PTRS-DMRS association field in scheduling DCI indicates (independent of number of layers) the association between PTRS antenna port x and scheduled DMRS antenna port(s) corresponding to first and second SRS resource indicator and/or first and second precoding information and number of layers.

[0097] In one example, MSB and LSB bits are repurposed by defining the restricted set of MSB and LSB combinations allowed for the UE. For example, PUSCH transmission with two layers (straightforward to extend also with higher number of layers): ‘00’

MSB: a 1st scheduled DMRS port corresponding to SRS resource indicator field and/or Precoding information and number of layers field;

LSB: a 1st scheduled DMRS port corresponding to a second SRS resource indicator field and/or second Precoding information field.

‘ir

MSB: a 2nd scheduled DMRS port corresponding to SRS resource indicator field and/or Precoding information and number of layers field;

LSB: a 2nd scheduled DMRS port corresponding to a second SRS resource indicator field and/or a second Precoding information field.

[0098] When another PTRS-DMRS association field is configured, the association field indicates PTRS antenna port x associated with scheduled DMRS antenna port. In some embodiments, PTRS antenna port x can be associated with LSB or MSB. In some embodiments, PTRS antenna port x can be associated with the combination of LSB and MSB. Otherwise (i.e. no another PTRS-DMRS association field configured in scheduling DCI), RRC configured PTRS antenna port x is associated with indicated DMRS-PTRS association via the PTRS-DMRS association field.

[0099] When the PTRS-DMRS and another PTRS-DMRS association fields are configured for SFN based simultaneous multi-panel PUSCH transmission, the UE shall apply association between k-th scheduled DMRS antenna port and x-th indicated/configured PTRS antenna port when transmitting UL DMRS and PTRS resource with SFN based simultaneous multi-panel transmission by using both first SRI and second SRI and/or both first and second precoding information and number of layers.

[00100] In some embodiments, the PTRS-DMRS association indication can be configured with another solution different from Solutions A, B and C, which may be called as Solution D.

[00101] Particularly, two PTRS-DMRS association field may correspond to different SRS resource indicator field and/or different precoding information and number of layers fields. For example, a first PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field. A second PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00102] Additionally, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field. This solution may be called as solution D.

Solution D

[00103] In this solution, when the UE is scheduled with SFN based simultaneous multi-panel PUSCH triggered via DCI, the PTRS-DMRS association field indicates that DMRS port(s) associated to each SRI and precoder matrix indicator (PMI) are also associated to own PTRS antenna port. In other words, there are two PTRS antenna ports, PTRS antenna port per SRI and/or precoding information land layer information pair.

[00104] For example, the PTRS-DMRS association field in scheduling DCI indicates the association between PTRS antenna port x and scheduled DMRS antenna port(s) corresponding to first SRS resource indicator and/or first precoding information and number of layers. The second PTRS-DMRS association field in scheduling DCI indicates the association between PTRS antenna port y and scheduled DMRS antenna port(s) corresponding to second SRS resource indicator and/or second precoding information and number of layers.

[00105] In some embodiments, the PTRS-DMRS association indication may be comprised in downlink control information (DCI). In some embodiments, SFN specific PTRS-DMRS association may be defined.

[00106] With the embodiments as proposed herein, it may dynamically indicate DMRS- PTRS association for scheduled SFN based simultaneous multi-panel PUSCH transmission with precoding. Moreover, the corresponding UE behavior (i.e. how UE shall interpret indicated information) for proposed indication methods for SFN based simultaneous multipanel PUSCH transmission is provided.

[00107] In some embodiments, the gNB may select one of the above solutions to be applied when the UE receives scheduling DCI. For instance, the gNB may configure/activate Solution A or Solution B when the UE is to transmit simultaneously from two panels to a single TRP, and configure/activate Solution C when the UE is to transmit simultaneously from two panels to two TRPs, each panel having its own target receiving TRP. The selection of the solution to be applied could be configured via a RRC or, MAC or LI signaling.

[00108] Hereinafter, some specific example of the above solutions will be described in details with reference to Fig. 3 to 5.

[00109] Figure 3 illustrates a schematic diagram of uplink sounding reference signal (SRS) resource set configurations for SFN based simultaneous multi-panel PUSCH transmission with two layers according to some embodiments of the present disclosure. It shows an example of UL SRS resource configuration for SFN based ST x MP PUSCH with 2-layers with two TRPs, i.e. TRP1 302 and TRP2 304. UE 306 is equipped with two transmit antenna panels 308 and 310 which are used to transmit simultaneously PUSCH in SFN manner via two antenna panels i.e. panell 310 and panel2 308, with the capability of 2 TX antenna ports in each antenna panel. The UE 306 also includes a pre-coder PREC 1 328 and a pre-coder PREC 2 330. Based on the UE capability report, PUSCH TXCoherency is configured as ‘ fully AndPartialNonCoherent’ and DMRS-UplinkConfig is configured with phaseTrackingRS (i.e. PTRS-UplinkConfig) with maxNRofPorts=2.

[00110] Moreover, the UE 306 is configured with two UL SRS resource sets e.g. set#l 312 and set#2 314, with usage set to ‘codebook’ and with ‘followUnifiedTCIstateSRS-rl7’ where resource sets are configured with same or different number of resources with same or different number of antenna ports. Here, each UL SRS resource set has one SRS resource with 2-antenna ports, e.g. setl w/ 2-AP SRI#1 316 and set w/2-AP SRI#2 318. Furthermore, the UE 306 is configured with UE specific PUSCH-Config parameter, i.e. UL-TXMode-rl8 = SFN. The UE is dynamically indicated via DCI 1 1 or 1 2 with two different TCI states, TCLstatel (associated with TRP1) and TCI-state2 (associated with TRP2) which both UL SRS resource sets are configured to follow.

[00111] In Solution A, SFN based simultaneous multi-panel PUSCH transmission is scheduled via uplink DCI format 0 1 where the first DMRS-PTRS association field conveys information on association between scheduled DMRS antenna port and associated PTRS antenna port. Upon detection of DCI 0 1, the first SRI and second SRI codepoint field indicates SRI#1, SRI#4 and both first precoding and number of layers information and second precoding and number of layers information indicates 2 (with 2 layers but with different TPMIs). Moreover,

[00112] DMRS antenna ports indicates 0 (i.e. portO 322 and portl 320) and PTRS-DMRS association set to 0 (00). For codebook or non-codebook based UL transmission, the association between UL PTRS port(s) and DMRS port(s) is indicated by the first PTRS- DMRS association field(s). For example, PTRS ports include PTRS portO 324 and PTRS portl 326.

[00113] For illustrative purposes, Table 4 shows an example PTRS-DMRS association field. As shown, the MSB of PTRS-DMRS association field indicates the scheduled k-th, k=l . . .K (K=number of PUSCH layers), a DMRS antenna port corresponding to both a SRS resource indicator and a second SRS resource indicator field and/or both a precoding information and number of layers field and a second Precoding information and number of layers field. Furthermore, the LSB of PTRS-DMRS association field indicates n-th PTRS antenna port, where n=0. . .N-l (=1), where N defines the number of supported PTRS antenna ports and depends on the UE capability.

[00114] It is worth noting that the reserved bits in LSB can be used for indication of higher number of PTRS ports, e.g. 2 and 3. Moreover, the table can be easily extended to support higher number of scheduled DMRS antenna port, e.g. 8 by increasing 4 additional rows with two columns.

Table 4 PTRS-DMRS association for SFN based PUSCH up to four layers with UL PTRS port indication.

[00115] Furthermore, Fig. 4 illustrates another schematic diagram of uplink sounding reference signal (SRS) resource set configurations for SFN based simultaneous multi-panel PUSCH transmission with four layers according to some embodiments of the present disclosure. In Fig. 4, there are two TRPs, TRP1 402 and TRP2 404. UE 406 is equipped with two transmit antenna panels 408 and 410 which are used to transmit simultaneously PUSCH in SFN manner via two antenna panels i.e. panel#l 410 and panel#2 408, with the capability of 4 TX antenna ports in each antenna panel. Based on the UE capability report, PUSCH TXCoherency is configured as ‘ fully AndPartialNonCoherent’ and DMRS- UplinkConfig is configured with phaseTrackingRS (i.e. PTRS-UplinkConfig) with maxNRofPorts=2.

[00116] Moreover, the UE 406 is configured with two UL SRS resource sets e.g. set#l 416 and set#2418, with usage set to ‘codebook’ and with ‘followUnifiedTCIstateSRS-rl7’ where resource sets are configured with same or different number of resources with same or different number of antenna ports. Each UL SRS resource set has one SRS resource with 4- antenna ports, e.g. set#l w/ 4-AP SRI#1 420 and set#2 w/ 4-AP SRI#1 422. Furthermore, the UE is configured with UE specific PUSCH-Configuration parameter, i.e. UL-TXMode-rl8 = SFN.

[00117] In this example, Solution A may be extended to operate with 4-layers and same principles as described earlier with two PUSCH layers can be applied. In this example, four DMRS ports and two PTRS ports are used. For example, one DMRS port is selected from DMRS port P0 424, DMRS port Pl 426, DMRS port P2 428, DMRS port P3 430, and the associated PTRS port is selected from PTRS portO 432 and PTRS portl 434.

[00118] In some embodiments, the Solution B may be used, the PTRS-DMRS association field can be the same as the PTRS-DMRS association field in Solution A and different lies in that two PTRS-DMRS association fields are used for the lower lays and the higher layers respectively and the lay number indication may help to determine which one indicates the DMRS-PTRS association.

[00119] For the Solution C, upon detection of DCI 0 1, the first SRI and second SRI codepoint field indicates SRI#1, SRI#4 and both first precoding and number of layers information and second precoding and number of layers information indicates 2 (with 2 layers but with different TPMIs). Moreover, DMRS antenna ports indicate 0 (i.e. ports 0 and 1) and PTRS-DMRS association set to 11. For codebook or non-codebook based UL transmission, the association between UL PT-RS port(s) and DM-RS port(s) is indicated by PTRS-DMRS association field(s) where the indicated value is 11, as shown in Table 5.

[00120] When PTRS-DMRS association is set to 11 and the number of configured PTRS antenna ports is one, the UE shall associate PTRS antenna port, i.e. port 0, to both indicated DMRS antenna ports, i.e. pO and pl which are associated with indicated SRI (i.e. SRI#1) of first UL SRS resource set (i.e. set#l) and SRI (i.e. SRI#4) of the second UL SRS resource set (i.e. set#2).

[00121] In fact, when the UE is configured with SFN based simultaneous PUSCH transmission, the UE shall assume that indicated PTRS-DMRS association values are restricted to only values ‘ 11’ or ‘00’. In other words, for SFN based codebook PUSCH transmission with single PTRS antenna port, the UE shall assume single PTRS antenna port is always indicated to same scheduled DMRS antenna port(s) independent of the number of SRS resource indicators (i.e. 1st or 2nd SRIs).

[00122] Fig. 5 shows an example 500 of allowed PTRS-DMRS association values for UL PTRS port 0 with dashed line. In this example, only the values 00 and 11 are used.

Table 5 Indicated codepoints via PCI 0 1 for SFN-based ST x MP PUSCH

[00123] In this way, network is dynamically indicated for the UE DMRS-PTRS antenna port association for SFN based simultaneous multi-panel PUSCH transmission

[00124] In some embodiments, for the Solution D, the structure of the PTRS-DMRS association field may be similar to or the same as that of Solution A. [00125] Fig. 6 shows a flowchart of an example method 600 implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the terminal device 110 with reference to Fig. 1.

[00126] At block 602, the terminal device 110 receive, from a network device, a phasetracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port. At block 604, the terminal device 110 transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

[00127] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field. The second part is configured to indicate a scheduled DMRS port sharing a PTRS port.

[00128] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00129] In some embodiments, the terminal device 110 may obtain, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00130] In some embodiments, the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00131] In some embodiment, the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold. [00132] In some embodiment, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00133] In some embodiment, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00134] In some embodiment, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00135] In some embodiment, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00136] Fig. 7 shows a flowchart of an example method 700 implemented at a network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the network device.

[00137] At block 702, the network device transmit a phase-tracking reference signal (PTRS)- demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port. At block 704, the network device receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00138] In some embodiment, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

[00139] In some embodiment, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00140] In some embodiment, the network device may determine a number of layers for the terminal device to transmit the uplink signal in the SFN manner; transmit a layer number indication indicative of the number of layers to the terminal device; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00141] In some embodiment, the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00142] In some embodiment, the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00143] In some embodiment, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00144] In some embodiment, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00145] In some embodiment, wherein PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00146] In some embodiment, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00147] In some embodiment, a terminal device comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS- DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

[00148] In some embodiment, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part is configured to indicate a scheduled DMRS port sharing a PTRS port.

[00149] In some embodiment, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00150] In some embodiment, the terminal device is further caused to obtain, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00151] In some embodiment, the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00152] In some embodiment, the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00153] In some embodiment, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00154] In some embodiment, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00155] In some embodiment, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00156] In some embodiment, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00157] In some embodiment, a network device comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS- DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00158] In some embodiment, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

[00159] In some embodiment, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00160] In some embodiment, the network device is further caused to determine a number of layers for the terminal device to transmit the uplink signal in the SFN manner; transmit a layer number indication indicative of the number of layers to the terminal device; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS- DMRS association field or the another PTRS-DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port. [00161] In some embodiment, the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00162] In some embodiment, the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00163] In some embodiment, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00164] In some embodiment, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00165] In some embodiment, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00166] In some embodiment, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00167] In some embodiments, an apparatus capable of performing any of the method 600 (for example, the terminal device 110) may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[00168] In some embodiments, the apparatus comprises: means for receiving, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and means for transmitting, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the apparatus.

[00169] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part is configured to indicate a scheduled DMRS port sharing a PTRS port.

[00170] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00171] In some embodiments, the apparatus comprises: means for obtaining, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and means for selecting, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00172] In some embodiments, the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00173] In some embodiments, the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00174] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00175] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field. [00176] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00177] In some embodiments, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00178] In some embodiments, an apparatus capable of performing any of the method 700 (for example, the network device) may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[00179] In some embodiments, the apparatus comprises: means for transmitting a phasetracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and means for receiving, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00180] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

[00181] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00182] In some embodiments, the apparatus further comprises: means for determining a number of layers for the terminal device to transmit the uplink signal in the SFN manner; means for transmitting a layer number indication indicative of the number of layers to the terminal device; and means for selecting, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS- DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00183] In some embodiments, the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00184] In some embodiments, the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00185] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00186] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00187] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00188] In some embodiments, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00189] In some embodiments, a non-transitory computer readable medium comprises program instructions that, when executed by an apparatus, cause the apparatus to perform: receiving a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication from a network device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmitting an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two and more antenna panels of the apparatus, based on the PTRS-DMRS association indication. [00190] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part is configured to indicate a scheduled DMRS port sharing a PTRS port.

[00191] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00192] In some embodiments, the program instructions further causes the apparatus to perform: obtaining, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and selecting, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port .

[00193] In some embodiments, the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00194] In some embodiments, the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00195] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00196] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00197] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00198] In some embodiments, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00199] In some embodiments, a non-transitory computer readable medium comprises program instructions that, when executed by an apparatus, cause the apparatus to perform: transmitting a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receiving an uplink signal from a terminal device in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00200] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

[00201] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00202] In some embodiments, the program instructions further causes the apparatus to perform: determining a number of layers for the terminal device to transmit the uplink signal in the SFN manner; transmitting a layer number indication indicative of the number of layers to the terminal device; and selecting, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS- DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00203] In some embodiments, the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00204] In some embodiments, the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00205] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00206] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00207] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00208] In some embodiments, wherein the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00209] In some embodiments, a computer program comprises instructions, which, when executed by an apparatus, cause the apparatus at least to: receive, from a network device, a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the apparatus.

[00210] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part is configured to indicate a scheduled DMRS port sharing a PTRS port. [00211] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00212] In some embodiments, the apparatus is further caused to: obtain, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00213] In some embodiments, wherein the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00214] In some embodiments, the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00215] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00216] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00217] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00218] In some embodiments, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00219] In some embodiments, a computer program comprises instructions, which, when executed by an apparatus, cause the apparatus at least to: transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00220] In some embodiments, the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

[00221] In some embodiments, the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS-DMRS association field has a same structure as the PTRS-DMRS association field.

[00222] In some embodiments, the apparatus is further caused to: determine a number of layers for the terminal device to transmit the uplink signal in the SFN manner; transmit a layer number indication indicative of the number of layers to the terminal device; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS- DMRS association field or the another PTRS-DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

[00223] In some embodiments, the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

[00224] In some embodiments, the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

[00225] In some embodiments, the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

[00226] In some embodiments, the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

[00227] In some embodiments, PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

[00228] In some embodiments, the PTRS-DMRS association indication is comprised in downlink control information (DCI).

[00229] FIG. 8 is a simplified block diagram of a device 800 that is suitable for implementing embodiments of the present disclosure. The device 800 may be provided to implement the communication device, for example the terminal device 110 as shown in Fig. 1 or the network device 120 and 130. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processor 810, and one or more communication modules 840 coupled to the processor 810.

[00230] The communication module 840 is for bidirectional communications. The communication module 840 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

[00231] The processor 810 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[00232] The memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 824, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 822 and other volatile memories that will not last in the power-down duration.

[00233] A computer program 830 includes computer executable instructions that are executed by the associated processor 810. The program 830 may be stored in the ROM 824. The processor 810 may perform any suitable actions and processing by loading the program 830 into the RAM 822.

[00234] The embodiments of the present disclosure may be implemented by means of the program 830 so that the device 800 may perform any process of the disclosure as discussed with reference to Figs. 2 to 7. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[00235] In some embodiments, the program 830 may be tangibly contained in a computer readable medium which may be included in the device 800 (such as in the memory 820) or other storage devices that are accessible by the device 800. The device 800 may load the program 830 from the computer readable medium to the RAM 822 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. Fig. 8 shows an example of the computer readable medium 900 in form of CD or DVD. The computer readable medium has the program 830 stored thereon.

[00236] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[00237] 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, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the method 600 or 700 as described above with reference to Figs. 2-6. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[00238] Program code for carrying out 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, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[00239] In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[00240] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but 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 computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, 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 compact disc read-only memory (CD- ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[00241] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[00242] Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure 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

WHAT IS CLAIMED IS:

1. A terminal device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: receive, from a network device, a phase-tracking reference signal (PTRS)- demodulation reference signal (DMRS) association indication, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmit, based on the PTRS-DMRS association indication, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two or more antenna panels of the terminal device.

2. The terminal device of claim 1, wherein the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field; and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part is configured to indicate a scheduled DMRS port sharing a PTRS port.

3. The terminal device of claim 1, wherein the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS- DMRS association field has a same structure as the PTRS-DMRS association field.

4. The terminal device of claim 3, wherein the terminal device is further caused to: obtain, from the network device, a layer number indication indicative of a number of layers configured for transmitting the uplink signal in the SFN manner; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port .

5. The terminal device of claim 4, wherein the PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

6. The terminal device of claim 4, wherein the another PTRS-DMRS association field is selected to determine the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

7. The terminal device of any of claims 2-5, wherein the first part comprises one or more most significant bits (MSB) of the PTRS-DMRS association field and the second part comprises one or more least significant bits (LSB) of the PTRS-DMRS association field.

8. The terminal device of Claim 3, wherein the PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a first sounding reference signal (SRS) resource indicator field and/or a first precoding information and number of layers field; and the another PTRS-DMRS association field is configured to indicate a PTRS-DMRS association corresponding to a second SRS resource indicator field and/or a second precoding information and number of layers field.

9. The terminal device of Claim 8, wherein PTRS ports corresponding to the first SRS resource indicator and/or the first precoding information and number of layers field are at least partially different from PTRS ports corresponding to the second SRS resource indicator and/or the second precoding information and number of layers field.

10. The terminal device of Claim 1, wherein the PTRS-DMRS association indication is comprised in downlink control information (DCI).

11. A network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit a phase-tracking reference signal (PTRS)-demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receive, from the terminal device, an uplink signal in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

12. The network device of claim 11, wherein the first part is configured to indicate a scheduled DMRS port corresponding to both a first sounding reference signal (SRS) resource indicator field and a second SRS resource indicator field, and/or both a first precoding information and number of layers field and a second precoding information and number of layers field, and wherein the second part indicates a scheduled DMRS port sharing a PTRS port.

13. The network device of claim 11, wherein the PTRS-DMRS association indication further comprises another PTRS-DMRS association field, and wherein the another PTRS- DMRS association field has a same structure as the PTRS-DMRS association field.

14. The network device of claim 13, wherein the network device is further caused to: determine a number of layers for the terminal device to transmit the uplink signal in the SFN manner; transmit a layer number indication indicative of the number of layers to the terminal device; and select, based on the number of layers and a predetermined layer number threshold, one of the PTRS-DMRS association field or the another PTRS-DMRS association field to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

15. The network device of claim 14, wherein the PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is not higher than the predetermined layer number threshold.

16. The network device of claim 14, wherein the another PTRS-DMRS association field is selected to indicate the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port when the number of layers is higher than the predetermined layer number threshold.

17. A method comprising: receiving, by a terminal device, a phase-tracking reference signal (PTRS)- demodulation reference signal (DMRS) association indication from a network device,, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and transmitting, by the terminal device, an uplink signal to the network device in a single frequency network (SFN) manner simultaneously via two and more antenna panels of the terminal device, based on the PTRS-DMRS association indication.

18. A method comprising: transmitting, by a network device, a phase-tracking reference signal (PTRS)- demodulation reference signal (DMRS) association indication to a terminal device, wherein the PTRS-DMRS association indication comprises a PTRS-DMRS association field having a first part indicative of a scheduled DMRS port and a second part indicative of a PTRS port associated with the scheduled DMRS port; and receiving, by the network device, an uplink signal from a terminal device in a single frequency network (SFN) manner on the scheduled DMRS port and the PTRS port associated with the scheduled DMRS port.

19. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method of claim 17 or 18.

20. An apparatus (800) comprising means (810, 820, 840) for performing at least the 5 method according to claim 17 or 18.