Apparatuses and methods for timing offset compensation for inter-transmission reception point

Abstract

The exemplary embodiment of this disclosure relates to a time offset compensation solution. In this solution, a first device determines precoding matrix indicator (PMI) information based on measurements on multiple channel status information reference signal (CSI-RS) resources and at least one first time offset, and sends a PMI report containing the PMI information to a second device, wherein each of the at least one first time offset corresponds to one of the multiple CSI-RS resources.

Description

Timing offset compensation between transmitting and receiving points Many of the exemplary embodiments of this disclosure are generally related to the field of telecommunications, and particularly to methods, apparatus, devices and computer-readable storage media for compensating for timing offsets between transmission reception points (TRPs). Coherent joint transmission (CJT) provides downlink spectral benefits and coverage gain. Release 18 improved Type-II CSI to accommodate CJT, provided there is adequate synchronization and backhaul. Some scenarios—such as inter-site CJT and base stations equipped with distributed remote radio heads (RRHs)—require additional latency and phase / frequency correction. As user equipment (UE) gains more knowledge about downlink (DL) channel conditions in both frequency division duplexing (FDD) and time division duplexing (TDD), the need for TRP (transmission-to-return) correction reports measured from the channel status information (CSI) reference signal (RS) (i.e., CSI-RS) is clearly not only for expanding deployment scenarios but also for providing added robustness to CJT operations. Therefore, in connection with Release No. 19, one of the following objectives related to CJT improvement was proposed and agreed upon: to describe the improvement of UE reporting for CJT deployment under non-ideal synchronization and backhaul conditions, targeting both frequency range 1 (FR1), frequency division duplex (FDD) and time division duplex (TDD) aspects, such as time error and frequency / phase offset measurement between transceiver points (TRPs), and reporting performed as independent, irregular reports on the physical uplink shared channel (PUSCH), assuming the use of the legacy CSI-RS design. In one first aspect of this disclosure, a first device is provided. The first device includes at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first device to at least: determine precoding matrix indicator (PMI) information based on measurements on a plurality of Channel State Information Reference Signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and send a PMI report containing the PMI information to a second device. In a second aspect of this disclosure, a second device is provided. The second device includes at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the second device to at least: receive a precoding matrix indicator (PMI) report from the first device, the PMI report including PMI information determined by the first device based on measurements on a plurality of Channel State Information Reference Signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and determine, based on the PMI information, a precoder to be applied to a transmission between the first device and the second device. In a third aspect of this disclosure, a method is provided. The method includes: determining precoding matrix indicator (PMI) information based on measurements on a plurality of channel status information reference signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and sending a PMI report containing the PMI information to a second device. In one fourth aspect of this disclosure, a method is provided. The method includes: receiving a precoding matrix indicator (PMI) report from a first device, the PMI report including PMI information determined by the first device based on measurements on a plurality of Channel State Information Reference Signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and determining a precoder to be applied to a transmission between the first device and the second device based on the PMI information. In a fifth aspect of this disclosure, a first device is provided. The first device includes: means for determining precoding matrix indicator (PMI) information based on measurements on a plurality of channel status information reference signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and means for sending a PMI report to a second device, the PMI report containing the PMI information. In a sixth aspect of this disclosure, a second device is provided. The second device includes: means for receiving a precoding matrix indicator (PMI) report from the first device, the PMI report including PMI information determined by the first device based on measurements on a plurality of Channel State Information Reference Signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and means for determining a precoder to be applied to a transmission between the first device and the second device based on the PMI information. In one of the seventh aspects of this disclosure, a computer-readable medium is provided. This computer-readable medium includes instructions stored therein for causing a device to perform at least the method according to the third aspect. In one of the eighth aspects of this disclosure, a computer-readable medium is provided. This computer-readable medium includes instructions stored therein for causing a device to perform at least the method according to the fourth aspect. It should be understood that this summary is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. The principles of this disclosure will now be illustrated with reference to some exemplary embodiments. It should be understood that these embodiments are for illustrative purposes only, to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of this disclosure. The embodiments described herein can be implemented in various ways other than those described below. In the following description and scope of the patent application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In this disclosure, the terms "an embodiment," "an example embodiment," "an exemplary embodiment," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment is required to include that particular feature, structure, or characteristic. Furthermore, these terms do not necessarily refer to the same embodiment. Also, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is hereby stated that making that feature, structure, or characteristic function in connection with other embodiments falls within the knowledge of those skilled in the art, whether or not it is stated. It should be understood that although terms such as "first," "second," and others may be used herein to describe various elements, these elements should not be limited by such terms. These terms are merely used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the exemplary embodiments. When used herein, the term "and / or" includes any one or more of the listed items and all combinations thereof. When used herein, "at least one of the following: " and " at least one of them" and other similar phrases mean at least one of the elements, or at least two or more of the elements, or at least all of the elements, wherein the list containing two or more elements is connected by "and" or "or". When used in this text, unless otherwise stated, "in response to A" does not mean that the step is performed immediately after "A" occurs, and may involve one or more intermediate steps. The terminology used herein is intended to describe particular embodiments only and is not intended to limit the exemplary embodiments. When used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless otherwise expressly indicated in the context. It will be further understood that, when used herein, the words “comprising,” “including,” “having,” “having,” “including,” and / or “comprising” indicate the presence of the stated features, elements, and / or components, etc., and do not exclude the addition or presence of one or more other features, elements, components, and / or combinations thereof. When used in this application, the term "circuit system" may refer to one or more or all of the following: (a) a purely hardware circuit implementation (e.g., an implementation only in analog and / or digital circuit systems), and (b) a combination of hardware circuitry and software, such as (if applicable): (i) a combination of analog and / or digital hardware circuitry and software / firmware, and (ii) any part of a hardware processor (including a digital signal processor, software, and memory) with software that works together to enable a device—e.g., a mobile phone or a server—to perform various functions, and (c) hardware circuitry and / or processors that require software (e.g., firmware) to operate, but may not exist when the software is not required for operation, such as a microprocessor or a part of a microprocessor. This definition of circuit system applies to all uses of the term in this application—including in any claim. As a further example, when used in this application, the term circuit system B also covers implementations of a single hardware circuit or processor (or a plurality of processors), or a portion of a hardware circuit or processor and its accompanying software and / or firmware. The term circuit system B also covers, for example, baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or networking devices, if applicable to specific claim elements. When used herein, the term "communication network" refers to a network conforming to any suitable communication standard, such as New Radio (NR), 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 others like these. Furthermore, communication between a terminal device and a network device within the communication network can be performed according to any suitable generation of communication protocol, including but not limited to 1G, 2G, 2.5G, 2.75G, 3G, 4G, 4.5G, 5G, and / or any other currently known or future protocols. Embodiments of this disclosure can be applied to a variety of communication systems. Given the rapid development of communications, there will naturally be future types of communication technologies and systems that can be represented by this disclosure. This should not be construed as limiting the scope of this disclosure to the systems mentioned above. When used in this document, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. The network device may refer to a base station (BS) or access point (AP), such as a B node (NodeB or NB), an evolved B node (eNodeB or eNB), an NR NB (also known as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a repeater, an integrated access and backhaul (IAB) node, a low-power node (such as a femtosecond or picosecond), a non-terrestrial network (NTN) or non-terrestrial network device (such as a satellite network device, a low earth orbit (LEO) satellite, and a geosynchronous earth orbit (GEO) satellite), a spacecraft network device, and so on, depending on the terminology system and technology used. In some exemplary embodiments, the radio access network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) in the IAB donor node. The IAB node contains a mobile terminal (IAB-MT) portion that behaves like a UE towards the parent node, while the DU portion of the IAB node behaves like a base station towards the next-hop IAB node. The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (e.g., digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile radios, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB adapters (dongles), smart devices, customer-premises equipment (CPE), Internet of Things (IoT) devices, watches or other wearables, and head-mounted displays. HMDs, vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain environments), user electronic devices, devices operating on commercial and / or industrial wireless networks, and others of the like. A terminal device may also correspond to the mobile termination (MT) portion of an IAB node (e.g., a relay node). In the following description, the terms "terminal device," "communication device," "terminal," "user equipment," and "UE" may be used interchangeably. When used herein, the terms “resource,” “transmission resource,” “resource block,” “physical resource block (PRB),” “uplink resource,” or “downlink resource” can refer to any resource used for communication—such as communication between a terminal device and a network device—such as resources in the time domain, frequency domain, spatial domain, code domain, or any other resource enabling communication, and others like these. In the following text, time-domain resources will be used as examples of resources to illustrate some exemplary embodiments of this disclosure. Note that the exemplary embodiments of this disclosure can also be applied to other resources in other domains. In short, the resources used herein include, but are not limited to, time resources or frequency resources, such as subband non-overlapping full-duplex time resources, dynamic time-division multiplexing time resources, full-duplex evolution time resources, subbands, subcarriers, or resource elements (REs). Demonstration Environment Figure 1A illustrates a demonstrative communication environment 100A, within which several demonstrative embodiments of this disclosure can be implemented. Communication environment 100A includes a first device 110 and a second device 120. A service area provided by the second device 120 is referred to as a cell. The second device 120 may provide one or more cells. In some exemplary embodiments, the first device 110 may be included in a terminal device, and the second device 120 may be included in a network device serving the terminal device. Furthermore, the communication environment 100A may also include one or more third devices, namely third devices 130-1 to 130-4. The first device 110 and the second device 120 may communicate with each other via one or more of the third devices 130-1 to 130-4. In some exemplary embodiments, the third device 130 may be contained within a transceiver point (TRP) or a remote radio head (RRH). In the following description, for illustrative purposes, some exemplary embodiments are illustrated by operating the first device 110 as a terminal device and the second device 120 as a network device. However, in some exemplary embodiments, the operations described in connection with the terminal device may be performed at the network device or other devices, and the operations described in connection with the network device may be performed at the terminal device or other devices. In some exemplary embodiments, if the first device 110 is a terminal device and the second device 120 is a network device, then the link from the second device 120 to the first device 110 is referred to as a downlink (DL), and the link from the first device 110 to the second device 120 is referred to as an uplink (UL). In the DL, the second device 120 is a transmitting (TX) device (or transmitter), and the first device 110 is a receiving (RX) device (or receiver). In the UL, the first device 110 is a TX device (or transmitter), and the second device 120 is an RX device (or receiver). Communication in communication environment 100 may be implemented in accordance with any appropriate communication protocol, including but not limited to cellular communication protocols such as first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), sixth generation (6G) and others, wireless local area network communication protocols (such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and others), and / or any other currently known or future protocols. Furthermore, the communication may use any suitable wireless communication technology, including 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 Fourier Transform Spread OFDM (DFT-s-OFDM), and / or any other currently known or future technologies. Please now refer to Figure 1B, which illustrates a demonstrative communication environment 100B in which several demonstrative embodiments of this disclosure can be implemented. Demonstration Communication Environment 100B illustrates an example of a downlink single downlink control information (DCI) multiple TRP system, which consists of up to It consists of several cooperative TRPs (or TRP groups) connected via perfect backhaul links, and performs co-homogeneous transmission (CJT) to one or more co-scheduled UEs. It is assumed that all RRH / TRPs have the same array geometry in both polarizations. In azimuth angle There are one antenna port and at the elevation angle There are , and each TRP has a total of . The antenna port. In this example, each TRP is equipped with an antenna port. The dual-polarized array has a total of 32 transmit antenna ports spanning these TRPs. With the introduction of a Type-I single panel (SP) for non-coherent joint transmission (NCJT) from two TRPs, Publication No. 17 first introduced support for multiple TRP CSI reporting. As discussed earlier, CJT provides downlink spectral benefits and coverage gain. CJT differs from NCJT in that it assumes each MIMO layer can be transmitted from multiple TRP antenna ports, whereas in NCJT, each MIMO layer can only be transmitted from a single TRP. In Release No. 18, a new feature, eType-II-CJT, was introduced to improve Multiple Input Multiple Output (MIMO) CSI. This feature extends the support of eType-II codebooks to multiple TRP CSI reports for coherent joint transmission (CJT) in up to four distributed RRH or TRP scenarios. Both NCJT and CJT operations assume complete overlap of MIMO layers in time and frequency resources; that is, both assume that time synchronization between TRPs is within a cyclic prefix of a symbol. Conversely, CJT also assumes phase synchronization between TRPs, enabling precoding of a MIMO layer to be performed across multiple TRP antenna ports. In Type-II-CJT, a UE is assembled for measurement. One CSI-RS resource per TRP / per TRP group, wherein... It is the maximum number of TRP / TRP groups in the CJT cooperation set, and its selection A TRP (or TRP group) is used for CSI reporting. Therefore, the CJT reporting set contains a subset of the largest CJT cooperating set configured by gNBs. Generally, for this... For each selected TRP, the Type-II-CJT codebook structure is given by the following formula: In equation (1) above, (in ) is a matrix having rows formed by basis vectors of the chosen spatial-domain (SD). (in ) is a matrix having rows formed by selected frequency-domain (FD) basis vectors, while This is a matrix of combination coefficients. The FD basis vectors are defined by a discrete Fourier transform (DFT) codebook; therefore, there is a correspondence between the indices of the FD basis vectors and the channel propagation delay. In fact, the delay domain is the domain of the discrete signal obtained by performing the DFT transform on a signal measured in the frequency domain. Similarly, the SD basis vectors are defined by a DFT codebook; therefore, there is a correspondence between the indices of the SD basis vectors and the channel propagation arrival angle. SD basis vectors are selected separately for each reported TRP, while FD basis vectors can be selected separately for each TRP (if the codebook "mode-1" is configured), or jointly across TRPs (if the codebook "mode-2" is configured). Therefore, in the mode-2 case, the same set of FD basis vectors is used in the PMI representation for all TRPs, i.e. In both codebook modes, the number of FD basis vectors selected for each TRP or across TRPs—that is... In or various matrices The number of row vectors in the array is determined by a set of parameters. To define. One approach to selecting the codebook mode for the FD basis vectors on a per-TRP basis is to target a CJT scenario where the difference in propagation delay between the TRP and the receiver is large enough that the channel delay profiles of different TRPs cannot be accurately captured by a single FD basis vector without performance loss. The reason for this loss is that, in eType II CSI, it is assumed that a common set of FD component bases is used across all TRPs. When there is a significant propagation delay between different TRPs, finding a shared delay window is difficult, and CSI is not captured correctly. It is worth noting that the larger the delay window, the higher the UL overhead. In inter-site CJT scenarios, the cooperating TRPs are located at different cell sites. In this case, given the scale of the CJT deployment, the timing differences in reception between signals transmitted from the antenna ports of different TRPs can be quite large, especially in the presence of non-ideal backhaul. Figure 2A illustrates the results 200A of four channels measured on a port. In this example, without pre-alignment (or pre-compensation of the channels), the UE cannot capture channels from TRP 1 and 3 within a delay window. Figure 2B illustrates the average and nested edge performance of CJT with and without time offset (TO). Passage occurs when there is a time offset (TO) between different TRPs. Users are assumed to experience random delays between 0 and the cyclic prefix (CP) length. The maximum timing offset supported by Mode 1 is limited by the number of precoding matrix indicator (PMI) numbers in the frequency domain, i.e. For example, when And the number of subbands per PRB is At that time, the maximum delay = If the bandwidth is 10MHz and a normal CP is used, then the maximum CP length is = Therefore, the range of delays covered by Mode 1 is much smaller than the CP length. This can also be clearly seen in Figure 2B, which shows a significant loss of ~7% in the Mode 1 case. In Release No. 18, a higher value of R=2 is supported, which increases the delay range of Mode 1, but the UE is not required to implement this. It also leads to a higher feedback indirect burden. Therefore, relying on such a feature to recover the time offset between TRPs is inappropriate. It is expected that the UE will provide an independent report indicating the estimated time offset between the UE and the gNB to the gNB. To calculate the TO value, the UE can be configured to measure the TO value, for example, from received tracking reference signals (TRS). The TRS has a high density of three pilots per PRB in the frequency domain, so the maximum delay that can be calculated from the TRS is (continuing the analysis above). This is much higher than what can be supported through mode 1, and it can cover up to the length of the extended cyclic prefix (CP). Once the time offset is estimated and fed back to the gNB, the reference signal (i.e., CSI-RS) used to calculate the CSI on the UE side needs to be pre-compensated between different TRPs so that the shared delay window can be found and the CSI can be correctly captured. In a later stage, the same offset is applied by the gNB in ​​the user's physical downlink shared channel (PDSCH) transmission. Figure 2C illustrates the average and grid edge performance with and without TRP pre-compensation (line ② in Figure 2C). The challenge here is that although CSI-RS is configured in a UE-specific manner, CSI-RS is typically a cell-specific reference signal because it carries a significant DL indirect burden. The UE-specific pre-compensation on the TRP side causes CSI-RS to become a UE-specific reference signal; therefore, the DL indirect burden scales linearly with the number of deployed UEs. Please note that the time offset is due to time alignment errors between TRPs. The resulting time offset, that is, the time offset caused by the hardware, is common to all UEs within a TRP. The UE measures the combined delay of the propagation delay plus the time offset caused by the hardware. Among them, the propagation delay This is specific to each UE-TRP channel; therefore, the latency ultimately measured by the UE is specific to each UE. . One solution to avoid this problem is to perform pre-compensation of the CSI-RS signal on the UE side. This means that before calculating the CSI, the UE should apply appropriate time-domain compensation to ensure that the channel impulse responses (CIRs) from different TRPs are aligned in the delay domain and that the CSI is calculated properly. The challenge on the UE side now is determining which TO value the UE should apply. Generally, the CSI report is self-contained, meaning it should contain all the information needed to build the precoder on the gNB side. According to this disclosure, timing offset compensation between transceiver points (TRPs) can be implemented at the terminal device. Working principle and demonstration of communication Based on some exemplary embodiments of this disclosure, a solution related to a UE-side compensation scheme is provided. For the purposes of discussion, the following embodiments will be discussed with reference to FIG1A, for example using a first device 110 and a second device 120, wherein the first device 110 may operate as a terminal device and the second device 120 may operate as a network device. It should be understood that the operations performed by the first device 110 and the second device 120 should be coordinated. In other words, the second device 120 and the first device 110 should have a consensus on assembly or configuration, parameters, etc. Such a consensus can be achieved through any appropriate interaction between the second device 120 and the first device 110, or by applying the same rules / policies to the second device 120 and the first device 110. In the following text, although some operations are described from the perspective of the first device 110, it should be understood that the second device 120 should also perform corresponding operations. Similarly, although some operations are described from the perspective of the second device 120, it should be understood that the first device 110 should also perform corresponding operations. For the sake of brevity, some identical or similar content has been omitted in this text. Please refer to Figure 3, which illustrates a communication transmission process 300 based on some exemplary embodiments of the present disclosure. In operation, the first device 110 determines 340 PMI information based on measurements on multiple CSI-RS resources and at least one first time offset, wherein each of the at least one first time offset corresponds to one of the multiple CSI-RS resources. In some exemplary embodiments, each of these plurality of CSI-RS resources corresponds to a third device 130 (e.g., a TRP) serving the first device 110. As a specific example, there are four TRPs, TRP 0 through TRP 3, and CSI-RS resources 0 through 3 associated with TRP 0 through TRP 3 in a one-to-one manner. In some exemplary embodiments, the first device 110 may further pre-compensate at least one of the plurality of CSI-RS resources by using the respective corresponding first time offset. Next, the first device 110 sends a PMI report containing the PMI information to the second device 120. As a specific example, the PMI report could be included within a CSI report (also known as CSI feedback). As for the second device 120, after receiving the PMI report (which includes PMI information determined by the first device 110 based on measurements on the plurality of CSI-RS resources and at least a first time offset), the second device 120 determines, based on the PMI information, a precoder to be applied to the transmission between the first device 110 and the second device 120. With this pre-encoder, subsequent transmissions from the second device 120 to the first device 110 can be performed based on the pre-encoder 355. In other words, according to this disclosure, the first device can calculate the PMI information at least partially based on the time offset between different TRPs, and then the second device 120 can determine the precoder based on the PMI information. In this way, even if there may be time offsets between different TRPs, essentially synchronous transmission between different TRPs can be achieved. Furthermore, because the compensation is implemented in the first device 110, rather than in the second device 120 serving many terminal devices, the additional communication overhead of the second device 120 is avoided, and the processing complexity of the second device 120 is reduced. According to this disclosure, in some exemplary embodiments, the at least one first time offset may be determined by the first device 110 and provided to the second device 120. Alternatively, in some other embodiments, the at least one first time offset may be determined by the second device 120 and provided to the first device 110. These two different exemplary embodiments will be discussed separately below. We will first discuss an embodiment in which the at least one first time offset is determined by the second device 110. As shown in Figure 3, in some exemplary embodiments, before receiving PMI information, the second device 120 may send information indicating the at least one first time offset to the first device 110 330. In this way, the first device 110 and the second device 120 can reach a consensus on the time offset used to calculate PMI information. Furthermore, in some exemplary embodiments, it is indicated that the information regarding the at least one first time offset may be included within a MAC CE / DCI. Compared to RRC communication, MAC CE or DCI typically has a shorter periodicity with greater flexibility; therefore, the at least one first time offset determined by the second device 120 can be provided to the first device 110 in a timely manner. Furthermore, the second device 120 may determine the at least one first time offset based on at least one second time offset estimated by the first device 110, as discussed below. In some exemplary embodiments, the first device 110 may measure 305 or more downlink reference signals and determine at least one second time offset. As a specific example, for instance, the multiple downlink reference signals are multiple tracking reference signals (TRS) from different TRPs, and the first device 110 may determine the at least one second time offset by measuring the multiple TRSs, wherein each second time offset corresponds to one of the multiple TRPs. Next, in some exemplary embodiments, the first device 110 may send a measurement report containing the at least one second time offset to the second device 120, for example, via a stand-alone report. As for the second device 120, the second device 120 can determine 325 the at least one first time offset based on the reported second time offset, and send the determined first time offset 330 to the first device 110. Generally, the second device may have a broader overview of such TRPs, and therefore, the determined first time offset may have higher accuracy than the reported (estimated by the first device 110) second time offset. Through the above processing, the first device 110 and the second device 120 can reach a consensus on at least one first time offset. The second device can then trigger a (irregular) channel measurement. As illustrated in Figure 3, a reference signal (CSI-RS) can be sent from the second device to the first device 110 via different TRPs. The first device 110 can determine the PMI information in the manner described above. Considering that the determination of at least one first time offset by the second device 120 might incur additional communication overhead for reporting the at least one first time offset, the at least one first time offset could also be determined by the first device 110. Such exemplary embodiments will be discussed below. As illustrated in Figure 3, the first device 110 can determine the at least one first time offset by measuring multiple downlink reference signals. For example, the first device 110 can determine the at least one first time offset by measuring multiple TRS from different TRPs. Next, in some exemplary embodiments, the first device 110 may send a measurement report containing the at least one first time offset to the second device 320. In some exemplary embodiments, the following can be defined as a preset rule: when calculating PMI information, the first device 110 always uses the time offset from the last / least measurement report. Using this preset rule, after sending the measurement report 320, the first device 110 can determine the PMI information based on the time offset contained in the measurement report, and the second device 120 can also determine the precoder based on the reported PMI information and the time offset contained in the measurement report. Alternatively, or additionally, the first device 110 may report the at least one first time offset together with the PMI report. Specifically, in some exemplary embodiments, after determining the at least one first time offset (310), the first device 110 may store (315) the at least one first time offset. Next, the first device 110 may determine PMI information based on the stored first time offset, and may further send information indicating the at least one first time offset along with the PMI information; for example, the PMI report may include the PMI information and information about the at least one first time offset. As for the second device, after receiving the PMI report, the second device 120 may determine the precoder based on the reported PMI information and the reported at least one first time offset. Through the above processing operations, a solution for time offset compensation by the first device 110 becomes feasible. To better understand the above processing operations, some exemplary embodiments will be further discussed with reference to Figures 4 and 5. In the examples of Figures 4 and 5, the first device 110 is described as a UE, and the second device is described as a gNB. Please now refer to Figure 4, which illustrates a flowchart 400 of a method for time offset compensation based on some exemplary embodiments of the present disclosure. In the example of Figure 4, the at least first offset is determined by the second device 120. As illustrated in Figure 4, in block 410, the UE calculates and feeds back the time offset (TO) estimates of the different TRPs connected to it in a standalone report (i.e., the at least one second time offset). Therefore, in block 415, the gNB receives the TO estimates (from each UE). In block 425, the gNB can determine the actual TO compensation value it wants to apply for each UE-TRP link (per UE). In block 435, the gNB can inform the UE of the TO compensation value to be applied on CSI-RS via a new MAC-CE message or via DCI, and can trigger the UE via (irregular) CSI-RS transmission. Therefore, in block 420, the UE can receive the TO compensation value(e) from the gNB and use the TO compensation value(e) to pre-compensate CSI-RS before CSI calculation (especially for PMI calculation). In block 430, the UE can feed back the PMI report to the gNB, and in block 445, the gNB can use the PMI report and the transmitted TO compensation value to establish a downlink precoder. In Figure 4, the gNB can determine the actual values ​​of the delays that should be applied to CSI-RS and PDSCH for each UE, which is usually advantageous because the network usually has a broader overview than the UE. Please now refer to Figure 5, which illustrates a flowchart 500 of a method for time offset compensation based on some exemplary embodiments of the present disclosure. In the example of Figure 6, the at least first offset is determined by the first device 110. As illustrated in Figure 5, in block 510, the UE calculates and feeds back the TO estimates (i.e., the at least one second time offset) of the different TRPs connected to it in a standalone report. Therefore, in block 515, the gNB receives the TO estimates (from each UE). It is assumed that the UE will store these values ​​to be used in CSI-RS before processing the next CSI report. In block 525, the gNB triggers the UE via AP CSI-RS transmission. As for the UE, in block 520, the UE receives the AP CSI-RS and pre-compensates the AP CSI RS using the stored TO compensation value. Next, in block 530, the UE feeds back a PMI report containing the used TO compensation value. In block 535, the gNB uses the PMI report and the transmitted TO compensation value to establish the DL precoder. In other words, the UE needs to include the assumption of the TO compensation value used by the UE in CSI-RS pre-compensation in the PMI report. In addition, if there is no available stored value on the UE side, the gNB will also be notified, because the delay used in CSI-RS compensation will not be part of the PMI report. In Figure 5, it is required that the TO compensation value be stored within the UE (from the time of TO calculation in the standalone report to the time of AP CSI-RS triggering and CSI feedback calculation). Furthermore, feedback on these values ​​is also required to ensure a self-sufficient PMI report. However, no additional communication indirection burden (such as MAC CE or DCI in Figure 4) is needed to indicate the TO value. Furthermore, in some embodiments, the second device 120 may send a first message (e.g., MAC CE or DCI) for enabling / disabling time offset compensation (e.g., a UE-side compensation scheme) at the first device 110. As a specific example, the second device 120 may send the first message with a one-bit indication, where a bit value "1" / "0" indicates that the first device 110 wants to enable the time offset feature, and a bit value "0" / "1" indicates that the first device 110 wants to disable the time offset feature. Alternatively, or additionally, the second device 120 may send a second message (e.g., MAC CE or DCI) indicating how to compensate for the time offset—for example, which time offset compensation method (if there are more than two offset compensation methods) the first device 110 may use / operate. For instance, the second device 120 may trigger or operate a first time offset compensation method (where the first device determines the at least one first time offset) via a MAC CE / DCI, and the second device 120 may also trigger or operate a second time offset compensation method (where the second device 120 determines the at least one first time offset) via a MAC CE / DCI. In addition, the first device 110 may also provide the second device with information about its time offset compensation capabilities via, for example, RRC communication. This capability information includes, but is not limited to, whether the first device 110 supports time offset compensation at the first device 110, at least one time offset compensation method supported by the first device 110, etc. Demonstration method Figure 6 shows a flowchart of an exemplary method 600 implemented in a first device, based on some exemplary embodiments of the present disclosure. For the purposes of discussion, method 600 will be described from the viewpoint of the first device 110 in Figure 1A. At block 610, the first device determines precoding matrix indicator (PMI) information based on measurements on multiple channel status information reference signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the multiple CSI-RS resources. At block 620, the first device sends a PMI report containing the PMI information to a second device. In some exemplary embodiments, before determining PMI information, the first device may receive information from the second device indicating at least one first time offset determined by the second device. In some embodiments, the first device may determine at least one second time offset by measuring multiple downlink reference signals, send a measurement report including the at least one second time offset, and receive from the second device information indicating the at least one first time offset determined by the second device based on the at least second time offset. In some exemplary embodiments, it is indicated that the information of the at least one first time offset is included in a medium access control (MAC) control element (CE) or downlink control information (DCI). In some exemplary embodiments, the first device can determine the at least one first time offset by measuring multiple downlink reference signals. In some exemplary embodiments, the first device may send information indicating the at least one first time offset to the second device along with the PMI information and / or via a measurement report. In some exemplary embodiments, after determining the at least one first time offset, the first device may store the at least one first time offset. In some exemplary embodiments, the first device may pre-compensate at least one of the plurality of CSI-RS resources by using separate first time offsets. In some exemplary embodiments, each of the plurality of CSI-RS resources may correspond to a transceiver point (TRP) serving the first device, and the PMI report may be included in a CSI report. In some exemplary embodiments, the first device may include a terminal device, and the second device may include a network device. Figure 7 shows a flowchart of an exemplary method 700 implemented in a first device, based on some exemplary embodiments of the present disclosure. For the purposes of discussion, method 700 will be described from the viewpoint of the second device 120 in Figure 1A. At block 710, the second device receives a precoded matrix indicator (PMI) report from the first device. The PMI report includes PMI information determined by the first device based on measurements on multiple channel status information reference signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the multiple CSI-RS resources. At block 720, the second device determines, based on the PMI information, a precoder to be applied to the transmission between the first device and the second device. In some exemplary embodiments, the second device may send information indicating the at least one first time offset to the first device before receiving the PMI information. In some exemplary embodiments, the second device may receive a measurement report including the at least one second time offset determined by the first device by measuring multiple downlink reference signals, determine the at least one first time offset based on the at least one second time offset, and send the information indicating the at least one first time offset to the first device. In some exemplary embodiments, it is indicated that the information of the at least one first time offset is included in a Media Access Control (MAC) control element (CE) or Downlink Control Information (DCI). In some exemplary embodiments, the second device may receive information indicating the at least one first time offset via a measurement report or the PMI report. In some exemplary embodiments, the plurality of CSI-RS resources may each correspond to a transceiver point (TRP) serving the first device, and the PMI report may be included in a CSI report. In some exemplary embodiments, the first device may include a terminal device, and the second device may include a network device. Demonstration equipment, devices and media In some exemplary embodiments, a first device capable of performing any of method 600 (e.g., first device 110 in FIG. 1A) may include means for performing individual operations of method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit system or a software module. The first device may be implemented as first device 110 in FIG. 1A or may be included within first device 110. The first device includes means for determining precoded matrix indicator (PMI) information based on measurements on a plurality of channel status information reference signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and means for sending a PMI report to a second device, the PMI report containing the PMI information. In some exemplary embodiments, the first device may further include means for receiving information from the second device indicating the at least one first time offset determined by the second device before determining the PMI information. In some exemplary embodiments, the first device may further include means for determining at least one second time offset by measuring a plurality of downlink reference signals; means for sending a measurement report including the at least one second time offset; and means for receiving from the second device the information indicating the at least one first time offset determined by the second device based on the at least second time offset. In some exemplary embodiments, it is indicated that the information of the at least one first time offset is included in a Media Access Control (MAC) control element (CE) or Downlink Control Information (DCI). In some exemplary embodiments, the first device may further include means for determining the at least one first time offset by measuring a plurality of downlink reference signals. In some exemplary embodiments, the first device may further include means for sending information indicating the at least one first time offset to the second device together with the PMI information and / or via a measurement report. In some exemplary embodiments, the first device may further include means for storing the at least one first time offset after determining the at least one first time offset. In some exemplary embodiments, the first device may further include means for pre-compensating at least one of the plurality of CSI-RS resources by using separate first time offsets. In some exemplary embodiments, the plurality of CSI-RS resources may each correspond to a transceiver point (TRP) serving the first device, and the PMI report may be included in a CSI report. In some exemplary embodiments, the first device may include a terminal device, and the second device may include a network device. In some exemplary embodiments, a first device capable of performing any of method 700 (e.g., the second device 120 in FIG. 1A) may include means for performing individual operations of method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit system or a software module. The second device may be implemented as the second device 120 in FIG. 1A or may be included within the second device 120. The second device includes means for receiving a precoding matrix indicator (PMI) report from the first device, the PMI report including PMI information determined by the first device based on measurements on a plurality of Channel State Information Reference Signal (CSI-RS) resources and at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and means for determining a precoder to be applied to transmission between the first device and the second device based on the PMI information. In some exemplary embodiments, the second device may further include means for sending information indicating the at least one first time offset to the first device before receiving the PMI information. In some exemplary embodiments, the second device may further include means for receiving a measurement report, the measurement report including the at least one second time offset determined by the first device by measuring a plurality of downlink reference signals; means for determining the at least one first time offset based on the at least one second time offset; and means for sending the information indicating the at least one first time offset to the first device. In some exemplary embodiments, it is indicated that the information of the at least one first time offset is included in a Media Access Control (MAC) control element (CE) or Downlink Control Information (DCI). In some exemplary embodiments, the second device may further include means for receiving information indicating the at least one first time offset via a measurement report or the PMI report. In some exemplary embodiments, the plurality of CSI-RS resources may each correspond to a transceiver point (TRP) serving the first device, and the PMI report may be included in a CSI report. In some exemplary embodiments, the first device may include a terminal device, and the second device may include a network device. Figure 8 is a simplified block diagram of a device 800 suitable for implementing an exemplary embodiment of the present disclosure. The device 800 may be provided to implement a communication apparatus, such as the first device 110 or the second device 120 shown in Figure 1A. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processors 810, and one or more communication modules 840 coupled to the processors 810. Communication module 840 is used for bidirectional communication. Communication module 840 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface necessary for communication with other network elements. In some exemplary embodiments, communication module 840 may include at least one antenna. Processor 810 may be any type suitable for the technology network in this area, and may include one or more of the following: general purpose computer, special purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture, these examples are not limiting. Device 800 may have multiple processors, such as application-specific integrated circuit chips that are time-subject to a clock calibrated by the main processor. Memory 820 may include one or more non-electrically dependent memories and one or more electrically dependent memories. Examples of non-electrically dependent memories include, but are not limited to, read-only memory (ROM) 824, electrically programmable read-only memory (EPROM), flash memory, hard disks, compact discs (CDs), digital video disks (DVDs), optical discs, laser discs, and other magnetic and / or optical storage. Examples of electrically dependent memories include, but are not limited to, random access memory (RAM) 822, and other electrically dependent memories that will not persist during power-off periods. Computer program 830 includes computer-executable instructions that are executed by a associated processor 810. The instructions of program 830 may include instructions for performing operations / actions of some exemplary embodiments of this disclosure. Program 830 may be stored in memory, such as ROM 824. Processor 810 may perform any appropriate actions and processing by loading program 830 into RAM 822. The exemplary embodiments of this disclosure can be implemented by program 830, enabling device 800 to perform any processing operations of the disclosure discussed with reference to Figures 3 to 7. The exemplary embodiments of this disclosure can also be implemented by hardware or a combination of hardware and software. In some exemplary embodiments, program 830 may be tangibly incorporated in a computer-readable medium (e.g., in memory 820), which may be included in device 800 or other storage device accessible by device 800. Device 800 may load program 830 from the computer-readable medium into RAM 822 for execution. In some exemplary embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, and others like these. When used herein, the term "non-transitory" is a limitation on the medium itself (i.e., tangible, not signaling), and not a limitation on the persistence of data storage (e.g., RAM versus ROM). Figure 9 shows an example of a computer-readable medium 980, which may be in the form of a CD, DVD, or other optical storage disc. The computer-readable medium 980 stores a program 830 within it. Generally, various embodiments of this disclosure can be implemented in hardware or special-purpose circuitry, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while others may be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although various aspects of embodiments of this disclosure are illustrated and explained using block diagrams, flowcharts, or other graphic representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein can be implemented in non-limiting forms such as hardware, software, firmware, special-purpose circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof. Some exemplary embodiments of this disclosure also provide at least one computer program product tangibly stored on a computer-readable medium—such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions, such as those included in a program module, which are executed in a device on a target entity or virtual processor to implement any of the methods described above. Generally, a program module includes a routine, program, library, object, category, component, data structure, or other such entity that performs a particular task or implements a particular abstract data type. The functionality of the program module can be combined or divided among a plurality of program modules, as desired in various embodiments. The machine-executable instructions for the program module can be executed locally or in a distributed device. In a distributed device, the program module can be located in both local and remote storage media. The program code used to implement the methods disclosed herein may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, such that, when executed by the processor or controller, the program code causes the functions / operations described in the flowcharts and / or block diagrams to be performed. The program code may be executed entirely on a machine, partially on the machine as a standalone software package, partially on the machine and partially on a remote machine, or entirely on the remote machine or server. In the context of this disclosure, computer code or related data may be carried on any suitable carrier to enable a device, apparatus, or processor to perform the various processing operations and actions described above. Examples of such carriers include signals, computer-readable media, and others like these. Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination of the foregoing. More specific examples of computer-readable storage media include electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM, or flash memory), optical fibers, compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, although the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order, or that all illustrated operations must be performed to achieve the desired result. In some cases, multiplexing and parallel processing may be beneficial. Similarly, while some specific implementation details are included in the above discussion, they should not be construed as limiting the scope of this disclosure; rather, they are merely descriptions of features that may be specific to certain embodiments. Unless expressly stated, certain features described in the context of several different embodiments may also be combined and implemented in a single embodiment. Conversely, unless expressly stated, multiple features described in the context of a single embodiment may also be implemented in multiple embodiments in a separate or any suitable sub-combination manner. Although the disclosure has been described above in language specific to structural features and / or methodological actions, it should be understood that the disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms by which the claims are implemented. 100A: Demonstration Communication Environment; Communication Environment 100B: Demonstration Communication Environment 110: First Device 120: Second Device 130 (130-1, 130-2, 130-3, 130-4): Third Device 200A: Results 200B, 200C: Charts 300: Transmission Flow 305: Measurement 310, 325, 340, 350: Decision 315: Storage 320, 330, 335, 345: Transmission 355: Perform 400, 500: Flowcharts 410, 415, 420, 425, 430, 435, 445: Blocks 510, 515, 520, 525, 530, 535, 610, 620, 710 720: Block 600, 700: Demonstration method; method 800: Device; apparatus 810: Processor 820: Memory 822: Random Access Memory (RAM) 824: Read-Only Memory (ROM) 830: Computer program; program 840: Communication module 980: Computer-readable media Now, some exemplary embodiments will be described with reference to the accompanying drawings, in which: Figure 1A illustrates a model communication environment in which several exemplary embodiments of the present disclosure can be implemented; Figure 1B illustrates another exemplary communication environment in which several exemplary embodiments of this disclosure can be implemented; Figure 2A illustrates the results of measurements taken at four channels on a port. Figure 2B illustrates the average and grid edge performance of CJT with and without time offset (TO); Figure 2C illustrates another chart illustrating the average and grid edge performance of CJT with and without time offset (TO); Figure 3 illustrates a communication transmission diagram based on some exemplary embodiments of the present disclosure; Figure 4 illustrates a flowchart of a method for time offset compensation based on some exemplary embodiments of the present disclosure; Figure 5 illustrates a flowchart of a method for time offset compensation based on some exemplary embodiments of the present disclosure; Figure 6 is a flowchart illustrating a method implemented in a first device according to some exemplary embodiments of the present disclosure; Figure 7 is a flowchart illustrating a method implemented in a second device according to some exemplary embodiments of the present disclosure; Figure 8 illustrates a simplified block diagram of one of the apparatuses suitable for implementing several exemplary embodiments of the present disclosure; and Figure 9 illustrates a block diagram of an exemplary computer-readable medium based on some exemplary embodiments of the present disclosure. Throughout these diagrams, the same or similar labels represent the same or similar elements. 600: Demonstration method; method 610, 620: Square

Claims

1. A first device for communication, comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first device to at least: determine at least one first time offset by measuring a plurality of downlink reference signals; determine precoding matrix indicator (PMI) information based on measurements on a plurality of channel state information reference signal (CSI-RS) resources and the at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and send a PMI report to a second device, the PMI report including the PMI information and information indicating the at least one first time offset via a measurement report.

2. The first device as described in claim 1, wherein, It indicates that the information regarding at least one first time offset was sent together with the PMI information or via a separate measurement report.

3. The first device as claimed in claim 1, wherein, The first device is further caused to: after determining the at least one first time offset, store the at least one first time offset.

4. The first device as claimed in claim 1, wherein, The first device is further caused to: pre-compensate at least one of the plurality of CSI-RS resources by using each of the respective first time offsets.

5. The first device as claimed in claim 1, wherein, Each of these multiple CSI-RS resources corresponds to a transceiver point (TRP) serving the first device, and the PMI report is included in a CSI report.

6. The first device as claimed in claim 1, wherein, The first device includes or is included in a terminal device, and the second device includes or is included in a network device.

7. A second device for communication, comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the second device to at least: receive information indicating at least one first time offset from a first device via a measurement report, wherein, The at least one first time offset is determined by the first device by measuring a plurality of downlink reference signals; the first device receives a precoding matrix indicator (PMI) report, the PMI report including PMI information determined by the first device based on measurements on a plurality of channel status information reference signal (CSI-RS) resources and the at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and a precoder determined based on the PMI information to be applied to the transmission between the first device and the second device.

8. The second device as described in claim 7, wherein, It indicates that the information regarding at least one first time offset was received either together with the PMI information or via a separate measurement report.

9. A method for communication, comprising: determining at least one first time offset by a first device by measuring a plurality of downlink reference signals; determining precoding matrix indicator (PMI) information by the first device based on measurements on a plurality of channel state information reference signal (CSI-RS) resources and the at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and sending a PMI report to a second device, the PMI report including the PMI information and information indicating the at least one first time offset via a measurement report.

10. A method for communication, comprising: receiving information indicating at least a first time offset from a first device via a measurement report, wherein, The at least one first time offset is determined by the first device by measuring a plurality of downlink reference signals; the first device receives a precoding matrix indicator (PMI) report, the PMI report including PMI information determined by the first device based on measurements on a plurality of channel status information reference signal (CSI-RS) resources and the at least one first time offset, each of the at least one first time offset corresponding to one of the plurality of CSI-RS resources; and a precoder determined by a second device based on the PMI information to be applied to the transmission between the first device and the second device.

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