Time Synchronization in a Wireless Communication Network

Abstract

A system and method for time synchronization in a wireless communication network is disclosed. In one embodiment, a method implemented by a wireless communication device includes transmitting a signal for enhanced uplink timing estimation to an access node, the signal occupying more or separate physical resources compared to a corresponding signal transmitted for purposes other than the enhanced uplink timing estimation. The method further includes receiving a message including timing related information or a clock time from the access node in response to transmitting the signal for enhanced uplink timing estimation. In this manner, the wireless communication network is able to meet enhanced timing error requirements, for example, when interworking with a time sensitive network (TSN).

Description

Technical Field

[0001] Related Applications This application claims the benefit of International Application No. PCT / CN2021 / 083957, filed on Mar. 30, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure generally relates to wireless communication or mobile communication. More particularly, the present disclosure relates to a method for time synchronization between an access node and a wireless communication device in a wireless communication network. The present disclosure also relates to an apparatus and a computer program product adapted for the same purpose.

Background Art

[0003] To support Time Sensitive Network (TSN) time synchronization, the 3rd Generation Partnership Project (3GPP) 5th Generation System (5GS) is integrated with an external network as a TSN bridge (or a time-aware system). There are two synchronization systems under consideration, namely, 5GS synchronization and TSN domain synchronization. 5GS synchronization is specified in the 3GPP specifications for Next Generation (NG) Radio Access Network (RAN) synchronization, and TSN domain synchronization provides synchronization services to the TSN according to the Institute of Electrical and Electronics Engineers (IEEE) 802.1AS.

[0004] 5GS time synchronization needs to meet stringent accuracy requirements to support interworking with TSN. A severe use case in the context of TSN-5GS interworking is when the TSN grandmaster clock is located at an end station connected to a user equipment (UE) / device-side TSN translator (DS-TT). This new Release 17 use case involves two Uu interfaces in the 5GS path through which the TSN grandmaster clock is relayed (i.e., 5GS inlet to 5GS outlet). One variation of the use case is shown in Figure 1, where two UEs are connected to different next-generation node Bs (gNBs), which may introduce increased uncertainty compared to the case where those two UEs are both connected to the same gNB.

[0005] As shown in Figure 1, the 5GS simultaneity budget is the portion of the end-to-end simultaneity budget applicable between the inlet and outlet of 5GS. The synchronization error per Uu interface represents a part of the end-to-end simultaneity budget and consists of the uncertainty introduced when (a) sending the 5th Generation (5G) reference time from the gNB antenna to the UE antenna by including ReferenceTimeInfo in either the DLInformationTransfer radio resource control (RRC) message or System Information Block (SIB) 9 (SIB9), and then (b) adjusting the 5G reference time to reflect the downlink propagation delay.

[0006] In 3GPP TSG-RAN WG2 #113-e, the range of uncertainty for a single Uu interface, as shown in Table 1 below, was agreed upon. TIFF0007700262000001.tif24170

[0007] Release 17 RAN work item "Enhanced Industrial Internet of Things (IoT) and ultra-reliable and low latency communication (URLLC) support for NR" has the following goals, where propagation delay compensation is used to achieve time synchronization between a UE and its associated gNB. 5. Extension for time synchronization support: a. If any, the RAN impact on uplink time synchronization for TSN. [RAN2] b. Propagation delay compensation extension (including mobility issues if any). [RAN2, RAN1, RAN3, RAN4]

[0008] RAN1 agreed on the following at RAN1 #102e. The following options for propagation delay compensation are further considered in RAN1 · Option 1: TA-based propagation delay · Option 1a: Propagation delay estimation based on legacy timing advance (potentially with extended TA indication granularity). · Option 1b: Propagation delay estimation based on advanced timing extended for time synchronization (similar to 1a, but with TA adjustment error and updated RAN4 requirements for Te). · Option 1c: Propagation delay estimation based on new dedicated signaling with finer delay compensation granularity (signaling separated from TA so that the TA procedure is not affected). · Option 2: RTT-based delay compensation: · Propagation delay estimation based on the RAN management Rx-Tx procedure for time synchronization (FFS procedure / signaling extended or separated for positioning).

[0009] TA-based propagation delay compensation In cellular communication for uplink transmission synchronization, a Timing Advance (TA) command is utilized. The Timing Advance (TA) command is further classified into two types. 1. First, in connection setup, an absolute timing advance command is communicated to the UE in a Media Access Control (MAC) protocol data unit (PDU) Random Access Response (RAR) or in an absolute timing advance command MAC control element (CE) of Message B (MSGB). 2. After connection setup, relative timing correction can be sent to the UE using a Timing Advance command MAC CE (e.g., the UE can move or due to multipath from a changing environment).

[0010] The downlink propagation delay (PD) can be estimated for a given UE by: (a) first, adding the TA value indicated by the RAR and all subsequent TA values sent using the MAC CE, and (b) taking a certain portion of the total TA value resulting from the addition of all TA values (e.g., assuming the downlink propagation delay and the uplink propagation delay are essentially the same, 50% can be used). The PD can be utilized, for example, to accurately track the value of its clock on the UE side relative to the value of the clock in other network nodes to understand time synchronization dynamics.

[0011] RTT - based Propagation Delay Compensation In the case of the round - trip time (RTT) - based method, the UE receive - transmit (Rx - Tx) time difference and / or the gNB Rx - Tx time difference are measured at the UE side and the gNB side respectively, and then used to derive the propagation delay.

[0012] For example, two types of Timing Advance (TADV) can be defined. · Type 1: TADV = (gNB Rx - Tx time difference)+(UE E - UTRA Rx - Tx time difference), · Type 2: TADV = gNB Rx - Tx time difference.

[0013] For either Type 1 or Type 2, the propagation delay can be estimated as 1 / 2 * TADV.

[0014] For Type 2 TADV, the Rx - Tx time difference corresponds to the received uplink radio frame containing the PRACH from each UE.

[0015] UL Time Synchronization in New Radio (NR) In RRC_CONNECTED, the gNB plays the role of maintaining the timing advance so as to keep L1 synchronized. Serving cells that have the same uplink (UL) to which the same timing advance is applied and use the same timing reference cell are grouped in a timing advance group (TAG). Each TAG contains at least one serving cell having a configured uplink, and the mapping of each serving cell to the TAG is set by RRC.

[0016] For the primary TAG, the UE uses the primary cell (PCell) as the timing reference, except for shared spectrum channel access where in some cases a secondary cell (SCell) may also be used by the UE (see Section 7.1 of 3GPP Technical Specification (TS) 38.133 V17.0.0). For the secondary TAG, the UE may use any of the activated SCell of this TAG as the timing reference cell and should not change it unless necessary.

[0017] The timing advance update is signaled to the UE by the gNB via a MAC CE command. Such a command restarts a TAG - specific timer indicating whether the layer 1 (L1) is synchronized or not. When the timer is running, L1 is considered synchronized, and in other cases, L1 is considered not synchronized, and in that case, uplink transmission can be performed only on the physical random access channel (PRACH).

[0018] The TA timer is configured in the TAG-Config information element (IE) in the IE MAC-CellGroupConfig that is used to configure MAC parameters for a cell group, including DRX. The TAG-Config IE is currently defined as follows. TIFF0007700262000002.tif106170TIFF0007700262000003.tif35170

[0019] Timing Estimation Error in gNB In the following excerpt from 3GPP TS38.104, the PRACH timing detection error tolerance in NR (see 3GPP TS38.104 V17.1.0) is described. *****Start of excerpt from 3GPP TS38.104***** 8.4.2 PRACH Detection Requirements 8.4.2.1 General The probability of detection is the conditional probability of correct detection of the preamble when the signal is present. There are several error cases, namely, detecting a preamble different from what was sent, not detecting the preamble at all, or correct preamble detection but with an incorrect timing estimate. For AWGN and TDLC300-100, the timing estimation error occurs when the estimated error of the timing of the strongest path is greater than the time error tolerance given in Table 8.4.2.1-1. The performance requirements for high-speed trains (Tables 8.4.23-1 to 8.4.2.3-4) are optional. TIFF0007700262000004.tif3517011.4.2.2 PRACH Detection Requirements 11.4.2.2.1 General The detection probability is the conditional probability of correct detection of the preamble when the signal is present. There are several error cases, namely, detecting a preamble different from what was sent, not detecting the preamble at all, or correct preamble detection but with an incorrect timing estimate. For AWGN and TDLA30 - 300, a timing estimation error occurs when the estimated error in the timing of the strongest path is greater than the time error tolerance given in Table 11.4.2.2 - 1. TIFF0007700262000005.tif30170*****End of excerpt from 3GPP TS38.104*****

Summary of the Invention

[0020] A system and method for time synchronization in a wireless communication network are disclosed. In one embodiment, a method implemented by a wireless communication device includes transmitting, to an access node, a signal for extended uplink timing estimation, the signal occupying more or distinct physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation. The method further includes receiving, in response to transmitting the signal for extended uplink timing estimation, a message from the access node that includes timing relationship information or clock time. In this way, the wireless communication network can meet extended timing error requirements, for example, when interworking with a time - sensitive network (TSN).

[0021] In one embodiment, the signal for extended uplink timing estimation is a physical random access channel (PRACH) preamble for extended uplink timing estimation, and the PRACH preamble for extended uplink timing estimation occupies more or distinct physical resources compared to a PRACH preamble for purposes other than extended uplink timing estimation.

[0022] In one embodiment, a message including time-related information or clock time is a random access response. In one embodiment, a PRACH preamble has a bandwidth larger than 12 physical resource blocks (PRBs), and the PRACH preamble for purposes other than extended uplink timing estimation is 12 PRBs. In one embodiment, each PRB has a bandwidth of 15·2 μ ·12 kilohertz, and 15·2 μ kilohertz is the subcarrier spacing of each cell where the PRACH preamble is transmitted.

[0023] In one embodiment, the message includes timing-related information. In one embodiment, the timing-related information includes at least one of absolute timing advance, timing advance adjustment, and propagation delay. In another embodiment, the timing-related information includes a timing advance command, and the timing advance command has a granularity of K / 2μ, where μ is an integer greater than or equal to 0, and 15·2 μ kilohertz is the subcarrier spacing of each cell on which the PRACH preamble is transmitted, and K is less than 1,024. In one embodiment, K is a power-of-two value. In one embodiment, K is 512, 256, 128, 64, 32, or 16.

[0024] In one embodiment, the PRACH preamble is transmitted on a PRACH resource from a common set of PRACH resources for all wireless communication devices in each cell on which the PRACH preamble is transmitted. In another embodiment, transmitting the PRACH preamble is cell-specific and includes transmitting the PRACH preamble according to a RACH configuration that is common to all wireless communication devices in each cell on which the PRACH preamble is transmitted. In one embodiment, the PRACH preamble is one of a first set of PRACH preambles dedicated to time synchronization, and the first set of PRACH preambles is different from a second set of PRACH preambles defined for cells for random access for purposes other than extended uplink timing estimation. In one embodiment, the wireless communication device transmits a PRACH preamble from the first set of PRACH preambles in response to an indication from a higher layer that the random access procedure is for TSN time synchronization, or an indication that the TSN protocol has been initiated in the wireless communication device.

[0025] In one embodiment, transmitting the PRACH preamble is triggered by a downlink signal.

[0026] In one embodiment, transmitting the PRACH preamble while the wireless communication device is in a connected state. In one embodiment, transmitting the PRACH preamble is triggered by downlink control information (DCI) received from an access node while the wireless communication device is in a connected state. In one embodiment, the DCI includes a field indicating one or more PRACH occasions configured for extended uplink timing estimation. In one embodiment, transmitting the PRACH preamble while the wireless communication device is in a connected state is in accordance with settings received via device-specific or group-specific signaling.

[0027] In one embodiment, the PRACH preamble is transmitted on dedicated PRACH resources, and the PRACH mask index value defined for clock synchronization in a time-sensitive network (TSN) is used for the dedicated PRACH resources.

[0028] In one embodiment, transmitting the PRACH preamble includes transmitting the PRACH preamble according to a PRACH configuration for extended uplink timing estimation, and the PRACH configuration for extended uplink timing estimation is the same as the PRACH configuration for purposes other than extended uplink timing estimation but with an adjustable time-domain correction.

[0029] In one embodiment, transmitting the PRACH preamble includes transmitting the PRACH preamble according to a first power ramping step size that is larger than a second power ramping step size used for transmitting the PRACH preamble for purposes other than extended uplink timing estimation, a first backoff time that is smaller than a second backoff time used for transmitting the PRACH preamble for purposes other than extended uplink timing estimation, or both the first power ramping step size and the first backoff time.

[0030] In one embodiment, the signal for extended uplink timing estimation includes one or more uplink reference signals for extended uplink timing estimation, and the one or more uplink reference signals for extended uplink timing estimation occupy more or distinct physical resources as compared to the corresponding one or more reference signals transmitted for purposes other than extended uplink timing estimation. In one embodiment, the one or more uplink reference signals for extended timing estimation include aperiodic, semi-persistent, or periodic sounding reference signals (SRS), aperiodic, semi-persistent, or periodic demodulation reference signals (DMRS), or aperiodic, semi-persistent, or periodic phase-tracking reference signals (PTRS). In another embodiment, the one or more uplink reference signals for extended timing estimation include periodic reference signals. In one embodiment, the periodic reference signal has a bandwidth larger than the bandwidth of the corresponding periodic reference signal transmitted for purposes other than extended uplink timing estimation. In another embodiment, the one or more uplink reference signals for extended timing estimation include semi-persistent reference signals. In one embodiment, the periodicity of the semi-persistent reference signal is a function of the propagation delay estimation refresh periodicity. In one embodiment, the propagation delay estimation refresh periodicity is a function of an accurate reference time refresh from the access node to the wireless communication device, a generalized Precision Time Protocol (gPTP) message refresh periodicity from the TSN master clock to the associated TSN slave clock, or both. In another embodiment, the propagation delay estimation refresh periodicity is set independently of the upper layer reference time refresh. In one embodiment, the semi-persistent reference signal has an offset value with respect to the propagation delay estimation refresh periodicity. In one embodiment, the semi-persistent uplink reference signal has an associated validity period.

[0031] In one embodiment, one or more uplink reference signals for extended timing estimation include periodic reference signals. In one embodiment, the periodicity of the periodic reference signal is a function of the propagation delay estimation refresh periodicity. In one embodiment, the semi-persistent reference signal has an offset value with respect to the propagation delay estimation refresh periodicity.

[0032] In one embodiment, the message is a timing advance adjustment medium access control (MAC) control element (CE) or a radio resource control (RRC) message.

[0033] Corresponding embodiments of the wireless communication device are also disclosed. In one embodiment, the wireless communication device is adapted to transmit a signal for extended uplink timing estimation to an access node, where the signal occupies more or separate physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation. The wireless communication device is further adapted to receive, from the access node, a message including timing relationship information or clock time in response to transmitting the signal for extended uplink timing estimation.

[0034] In one embodiment, the wireless communication device comprises a wireless interface and one or more processors associated with the wireless interface. The one or more processors are configured to cause the wireless communication device to transmit a signal for extended uplink timing estimation to an access node, where the signal occupies more or separate physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation. The one or more processors are further configured to cause the wireless communication device to receive, from the access node, a message including timing relationship information or clock time in response to transmitting the signal for extended uplink timing estimation.

[0035] Embodiments of a method implemented by an access node are also disclosed. In one embodiment, the method implemented by the access node comprises receiving, from a wireless communication device, a signal for extended uplink timing estimation, wherein the signal for extended uplink timing estimation occupies more or separate physical resources compared to a corresponding signal for purposes other than extended uplink timing estimation. The method further comprises deriving timing relationship information based on the signal for extended uplink timing estimation and transmitting, in response to transmitting the signal for extended uplink timing estimation, a message including the timing relationship information or clock time to the wireless communication device.

[0036] Corresponding embodiments of the access node are also disclosed. In one embodiment, the access node is adapted to receive, from a wireless communication device, a signal for extended uplink timing estimation, wherein the signal for extended uplink timing estimation occupies more or separate physical resources compared to a corresponding signal for purposes other than extended uplink timing estimation. The access node is further adapted to derive timing relationship information based on the signal for extended uplink timing estimation and transmit, in response to transmitting the signal for extended uplink timing estimation, a message including the timing relationship information or clock time to the wireless communication device.

[0037] In one embodiment, an access node comprises one or more processors, which are configured to cause the access node to receive, from a wireless communication device, a signal for extended uplink timing estimation, where the signal for extended uplink timing estimation occupies more or different physical resources compared to a corresponding signal for purposes other than extended uplink timing estimation. The one or more processors are further configured to cause the access node to derive timing relationship information based on the signal for extended uplink timing estimation and, in response to transmitting the signal for extended uplink timing estimation, transmit a message including the timing relationship information or clock time to the wireless communication device.

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate some aspects of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

Brief Description of the Drawings

[0039]

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Best Mode for Carrying Out the Invention

[0040] The embodiments described below represent information for enabling those skilled in the art to practice these embodiments and show the best mode of practicing these embodiments. Reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and recognize application examples of these concepts that are not specifically addressed herein. It should be understood that these concepts and application examples fall within the scope of the present disclosure.

[0041] As used herein, relative terms such as "first" and "second", "upper" and "lower" may be used simply to distinguish one entity or element from another entity or element, without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the concepts described herein. The singular forms "a", "an" and "the" as used herein are to be construed to include the plural forms as well, unless the context clearly dictates otherwise. Further, the terms "comprises", "comprising", "includes" and / or "including" as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0042] In some embodiments described herein, terms such as "coupled", "connected", etc. may be used herein to indicate a connection, which may not necessarily be direct and may include wired and / or wireless connections.

[0043] The term "wireless communication device" in this specification can be any type of device capable of communicating with a network node or another communication device via a wireless signal. A wireless communication device can be a wireless communication device, a target device, a user equipment (UE), a device-to-device (D2D) wireless device, a machine-type wireless device or a wireless device capable of machine-to-machine (M2M) communication, a low-cost and / or low-complexity wireless device, a sensor equipped with a wireless device, a tablet, a mobile terminal, a smartphone, a laptop embedded equipment (LEE), a laptop-mounted device (LME), a USB dongle, a customer premise equipment (CPE), an Internet of Things (IoT) device, or a narrowband IoT (NB-IoT) device, etc. The communication device can be a vehicle capable of supporting V2X communication.

[0044] There are problems with the current solutions for the interworking of a timing-sensitive network (TSN) and a 5th generation system (5GS). More specifically, in a TSN network, more accurate time offset estimation is required for clock synchronization.

[0045] In the 3rd Generation Partnership Project (3GPP) New Radio (NR) up to Release 16, the timing advance (TA) estimated based on the Physical Random Access Channel (PRACH) can have a detection time error larger than the requirement for the maximum time error for TSN, which causes the uplink timing at the next-generation Node B (gNB) side to not be as synchronized as required by TSN. This problem mainly occurs in the low band when a small subcarrier spacing (SCS) is applied such that the number of Physical Resource Blocks (PRBs) used by one PRACH preamble transmission is fixed at 12 PRBs. Therefore, the PRACH bandwidth is smaller when a smaller SCS is used. Since the detection error is approximately inverse to the uplink signal bandwidth, this leads to a larger detection error.

[0046] Therefore, a new PRACH design is required for clock synchronization, and it is also necessary to determine whether and how to use dedicated PRACH resources or common PRACH resources.

[0047] Furthermore, different resource allocations of reference signals are required to meet the requirements for TSN-specific time offset estimation in order to use signals other than PRACH for time synchronization.

[0048] The present disclosure relates to embodiments for improving time estimation accuracy to guarantee uplink synchronization in TSN by using an extended PRACH with a common PRACH resource configuration or a dedicated PRACH resource configuration for time synchronization, and a PRACH mask for determining a PRACH resource for clock synchronization, and a modified PRACH configuration for clock synchronization. The present disclosure also relates to embodiments for improving time estimation accuracy to guarantee uplink synchronization in TSN by using signals other than PRACH for time synchronization, such as an aperiodic sounding reference signal (SRS), a semi-persistent SRS, and a periodic SRS. The present disclosure also relates to embodiments for improving time estimation accuracy to guarantee uplink synchronization in TSN by prioritizing PRACH power ramping when performing a retry for TSN.

[0049] In the following description, it is assumed that a wireless communication device, such as a user equipment (UE), is a node for determining its own clock time using signaling provided by an access node, such as an evolved Node B (eNB) or a gNB, to assist the communication device. Thus, the access node can send time information (e.g., absolute timing advance, timing advance adjustment, propagation delay information) to the communication device.

[0050] It should be understood that the same methodology can be modified / adapted such that the access node is a node for determining the clock time for the wireless communication device. In this case, the access node can estimate the propagation delay for the wireless communication device and take this into account before sending a reference time to the wireless communication device via, for example, UE-specific signaling (dedicated radio resource control (RRC) signaling, or a MAC control element (CE) in a media access control (MAC) protocol data unit (PDU), or layer 1 (L1) physical layer signaling). It should be understood that the procedures described below can be easily adapted.

[0051] In the following description, it is assumed that accurate reference time distribution and its associated propagation delay estimation and compensation are for the purpose of providing an accurate timestamp clock in the TSN time synchronization procedure. More precisely, it is used for the TSN time synchronization procedure that requires extremely accurate synchronization on the Uu interface with an accuracy of, for example, 100 nanoseconds (ns) or less. However, the following embodiments can be used independently, for example, to provide a timing source for the UE (an alternative to the global positioning system (GPS) clock), distribution of a local clock to the UE, etc.

[0052] Other applications that require accurate clock synchronization between two nodes in a network can also use the embodiments of the present disclosure. That is, the term "TSN" described in the embodiments can be replaced by other similar networks or use cases.

[0053] FIG. 2 shows an example of a wireless communication network. Wireless communication devices (e.g., user equipment (UE)) 101 and 103 can communicate with an access node 105 (e.g., eNB or gNB). Wireless communication devices 101 and 103 communicate with access node 105 on the Uu physical interface.

[0054] FIG. 3 is a flowchart showing a method for time synchronization implemented in a communication system according to an embodiment. The communication system includes a network node and a wireless communication device and can be the one described with reference to FIG. 2.

[0055] In step 310, the access node 105 receives from the wireless communication device 101 a PRACH preamble for extending timing detection. In this embodiment, the transmission of the preamble for extending timing detection occupies more or separate physical resources, such as bandwidth, compared to the normal level or the level for purposes other than extending timing detection, for example, for the purposes of random access and normal timing detection. Optionally, the physical resources for transmitting the preamble for extending timing detection are shared by all wireless communication devices in the cell associated with the access node, that is, the wireless communication devices 101 and 103 in FIG. 2.

[0056] In step 320, the access node 105 derives timing relationship information based on the preamble for extending timing detection. Optionally, the timing relationship information is at least one of absolute timing advance (TA), TA adjustment, and propagation delay (PD).

[0057] In step 330, the access node 105 sends to the wireless communication device 101 the timing relationship information or the clock time for the wireless communication device determined based on the timing relationship information.

[0058] In this embodiment, the timing relationship information may be included in the TA command transmitted to the wireless communication device 101. Preferably, the TA command is signaled with a granularity smaller or finer than the granularity for normal transmission timing adjustment of the physical uplink control channel (PUCCH) / physical uplink shared channel (PUSCH) / sounding reference signal (SRS).

[0059] In this embodiment, the random access channel (RACH) configuration is performed before step 310. The RACH configuration specifies how wireless communication devices within the cell associated with access node 105 perform PRACH transmissions. Optionally, the RACH configuration is cell-specific and common to all wireless communication devices within the cell associated with access node 105.

[0060] Optionally, according to the RACH configuration, unlike for non-TSN use cases, a preamble for extending timing detection has a portion of the PRACH resources within the cell associated with access node 105 reserved for the transmission of the preamble for extending timing detection.

[0061] In an exemplary example, wireless communication device 101 is in the RRC connected state. Before step 310, access node 105 triggers the RACH procedure by means of a physical downlink control channel (PDCCH) containing a downlink control information (DCI) format that specifies which (one or more) PRACH occasions are configured for extending timing detection. Thus, at step 310, wireless communication device 101 transmits a preamble for extending timing detection by means of dedicated PRACH resources.

[0062] Optionally, according to the RACH configuration, the dedicated PRACH resources may be shared by all wireless communication devices within the cell associated with access node 105 or used by a group of wireless communication devices.

[0063] Optionally, according to the RACH configuration, the PRACH mask signaled by the DCI is used to filter dedicated PRACH resources, to extend timing detection, or to determine common PRACH resources.

[0064] Optionally, the RACH configuration for clock synchronization has configurable time domain corrections.

[0065] Optionally, according to the RACH configuration, a higher power ramping step and / or a smaller backoff time are used to extend the timing detection.

[0066] FIG. 4 is a flowchart illustrating a method for time synchronization implemented in a communication system according to another embodiment. The communication system includes a network node and a wireless communication device, and may be the one described with reference to FIG. 2.

[0067] In step 410, the access node 105 sends a downlink (DL) signal to the wireless communication device 101 to trigger the uplink (UL) reference signal (RS) transmission.

[0068] In step 420, the access node 105 receives the UL RS from the wireless communication device 101. Optionally, the UL RS is selected from a group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0069] In step 430, the access node 105 derives timing relationship information based on the UL RS. Optionally, the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0070] In step 440, the access node 105 sends the timing relationship information, or a clock time for the wireless communication device determined based on the timing relationship information, to the wireless communication device.

[0071] FIG. 5 is a flowchart illustrating a method for time synchronization implemented in a communication system according to another embodiment. The communication system includes a network node and a wireless communication device, and may be the one described with reference to FIG. 2.

[0072] In step 510, the access node 105 sends the settings regarding the UL RS to the wireless communication device 101, and according to the settings, the wireless communication device 101 performs multiple UL RS transmissions.

[0073] Optionally, the UL RS is selected from a group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0074] Optionally, the setting is an RRC setting that specifies the periodicity of multiple UL RS transmissions and the offset of the periodicity of multiple UL RS transmissions with respect to the propagation delay (PD) refresh periodicity.

[0075] Optionally, the setting is an RRC setting that specifies the periodicity of multiple UL RS transmissions, the duration of multiple UL RS transmissions, and the offset of the periodicity of multiple UL RS transmissions with respect to the propagation delay (PD) refresh periodicity.

[0076] In step 520, the access node 105 sends a downlink (DL) signal to the wireless communication device 101 to trigger multiple UL RS transmissions.

[0077] In step 530, the access node 105 refreshes or updates the time synchronization in the following manner. - Each time the access node 105 receives one UL RS from the wireless communication device 101 or receives a predetermined number of UL RSs from the wireless communication device 101, the access node 105 derives respective timing relationship information based on the received UL RS(s), and then sends the respective timing relationship information, or the clock time for the wireless communication device determined based on the respective timing relationship information, to the wireless communication device 101.

[0078] Optionally, the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0079] In this embodiment, step 520 is optional. That is, the plurality of UL RS transmissions can be triggered either by a signal from the network side, for example, a DL signal from the access node, or spontaneously triggered in the wireless communication device according to the settings sent to the wireless communication device in step 510.

[0080] FIG. 6 is a flowchart showing a method for time synchronization implemented in a communication system according to an embodiment. The communication system includes a network node and a wireless communication device, and may be the one described with reference to FIG. 2.

[0081] In step 610, the wireless communication device 101 transmits a physical random access channel (PRACH) preamble from the access node 105 to extend timing detection. In this embodiment, the transmission of the preamble for extending timing detection occupies more or separate physical resources, for example, bandwidth, compared to the normal level for the purposes of random access and normal timing detection. Optionally, the physical resources for transmitting the preamble for extending timing detection are shared by all wireless devices in the cell associated with the access node, that is, the UEs 101 and 103 in FIG. 2.

[0082] In step 620, the wireless communication device 101 receives timing relationship information derived from the preamble for extending timing detection from the access node 105, or the clock time for the wireless communication device determined based on the timing relationship information. Optionally, the timing relationship information is at least one of absolute timing advance (TA), TA adjustment, and propagation delay (PD).

[0083] In this embodiment, the timing relationship information may be included in the TA command transmitted to the wireless communication device 101. Preferably, the TA command is signaled with a granularity smaller than or finer than the granularity for the normal transmission timing adjustment of the Physical Uplink Control Channel (PUCCH) / Physical Uplink Shared Channel (PUSCH) / Sounding Reference Signal (SRS).

[0084] In this embodiment, the Radio Access Channel (RACH) configuration is performed before step 610. The RACH configuration specifies how the wireless communication devices in the cell associated with the access node 105 perform PRACH transmission. Optionally, the RACH configuration is cell-specific and common to all wireless communication devices in the cell associated with the access node 105.

[0085] Optionally, according to the RACH configuration, unlike for the use cases of non-time-sensitive networks (TSN), a part of the PRACH resources in the cell associated with the access node 105 is reserved for the transmission of the preamble for extending the timing detection.

[0086] In an exemplary example, the wireless communication device 101 is in the RRC connected state. Before step 610, the wireless communication device 101 receives, from the access node 105 via the PDCCH, a control signal for triggering the RACH procedure. The control signal includes a Downlink Control Information (DCI) format that specifies which (one or more) PRACH occasions are configured for extending the timing detection. Thus, at step 610, the wireless communication device 101 transmits a preamble for extending the timing detection using dedicated PRACH resources.

[0087] Optionally, according to the RACH configuration, the dedicated PRACH resource is shared by all wireless communication devices in the cell associated with access node 105 or is allowed to be used by a group of wireless devices.

[0088] Optionally, according to the RACH configuration, the PRACH mask signaled by DCI is used to extend timing detection, to filter the dedicated PRACH resource, or to determine the common PRACH resource.

[0089] Optionally, the RACH configuration for clock synchronization has configurable time domain corrections.

[0090] Optionally, according to the RACH configuration, higher power ramping steps and / or smaller backoff times are used to extend timing detection.

[0091] FIG. 7 is a flowchart showing a method for time synchronization implemented in a communication system according to another embodiment. The communication system includes a network node and a wireless communication device and may be the one described with reference to FIG. 2.

[0092] In step 710, the wireless communication device 101 receives a downlink (DL) signal from the access node 105 for triggering UL RS transmission.

[0093] In step 720, the wireless communication device 101 transmits UL RS to the access node 105. Optionally, the UL RS is selected from a group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0094] In step 730, the wireless communication device 101 receives, from the access node 105, timing relationship information derived based on the UL RS, or the clock time for the wireless communication device determined based on the timing relationship information. Optionally, the timing relationship information is at least one of an absolute timing advance, TA adjustment, and propagation delay.

[0095] FIG. 8 is a flowchart showing a method for time synchronization implemented in a communication system according to another embodiment. The communication system includes a network node and a wireless communication device, and may be the one described with reference to FIG. 2.

[0096] In step 810, the wireless communication device 101 receives, from the access node 105, a setting for the UL RS, and in accordance with the setting, the wireless communication device 101 performs a plurality of UL RS transmissions.

[0097] Optionally, the UL RS is selected from a group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0098] Optionally, the setting is an RRC setting that specifies the periodicity of the plurality of UL RS transmissions and the offset of the periodicity of the plurality of UL RS transmissions with respect to the propagation delay (PD) refresh periodicity.

[0099] Optionally, the setting is an RRC setting that specifies the periodicity of the plurality of UL RS transmissions, the duration of the plurality of UL RS transmissions, and the offset of the periodicity of the plurality of UL RS transmissions with respect to the propagation delay (PD) refresh periodicity.

[0100] In step 820, the wireless communication device 101 receives, from the access node 105, a downlink (DL) signal for triggering a plurality of UL RS transmissions.

[0101] In step 830, the wireless communication device 101 performs or updates time synchronization according to the settings in the following manner.

[0102] Either send one UL RS to the access node 105 or, after sending a predetermined number of UL RSs to the access node 105, each time the wireless communication device 101 receives from the access node 105 each timing relationship information derived based on the (one or more) transmitted UL RSs, or the clock time for the wireless communication device determined based on each timing relationship information.

[0103] Optionally, the timing relationship information is at least one of absolute timing advance, TA adjustment, and propagation delay.

[0104] In this embodiment, step 820 is optional. That is, the multiple UL RS transmissions can be triggered either by a signal from the network side, for example, a DL signal from the access node, or spontaneously triggered in the wireless communication device according to the settings received from the access node in step 810.

[0105] FIG. 9 shows a processor-based implementation form of a network node that can be used to implement the embodiment described above. For example, the structure shown in FIG. 9 can be used to implement the concept in any of the above-described access nodes.

[0106] As shown, node 900 may include one or more wireless interfaces 910. The (one or more) wireless interfaces 910 may be based on, for example, NR technology or LTE technology. The (one or more) wireless interfaces 910 may be used to control a wireless communication device, such as any of the UEs described above. Further, node 900 may include one or more network interfaces 920. The (one or more) network interfaces 920 may be used, for example, for communication with one or more other nodes of a wireless communication network.

[0107] Further, node 900 may include one or more processors 930 coupled to interfaces 910, 920, and a memory 940 coupled to the (one or more) processors 930. By way of example, interfaces 910, 920, the (one or more) processors 930, and memory 940 may be coupled by one or more internal bus systems of node 900. Memory 940 may include read-only memory (ROM), such as flash ROM, random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM), mass storage, such as a hard disk or solid state disk, and the like. As shown, memory 940 may include software 950 and / or firmware 960. Memory 940 may include suitably configured program code to be executed by the (one or more) processors 930 to implement the functions described above for time synchronization, as described with respect to FIGS. 3-5.

[0108] It should be understood that the structure shown in FIG. 9 is only schematic and that node 900 may actually include additional components not shown, such as additional interfaces, such as a dedicated management interface, or additional processors, for the sake of clarity. It should also be understood that memory 940 may include additional program code for implementing known functions of an eNB or gNB.

[0109] According to some embodiments, a computer program may also be provided in the form of a physical medium storing program code and / or other data to be stored, for example, in memory 940, or by making the program code available for download or by streaming, to implement the functions of node 900.

[0110] FIG. 10 shows a processor-based implementation of a wireless communication device that may be used to implement the embodiments described above.

[0111] As shown, wireless communication device 1000 includes one or more wireless interfaces 1010. The (one or more) wireless interfaces 1010 may be based on, for example, NR technology or LTE technology.

[0112] Furthermore, wireless communication device 1000 may include one or more processors 1020 coupled to the (one or more) wireless interfaces 1010 and a memory 1030 coupled to the (one or more) processors 1020.

[0113] As an example, one or more wireless interfaces 1010, one or more processors 1020, and a memory 1030 can be coupled by one or more internal bus systems of the wireless communication device 1000. The memory 1030 can include read-only memory (ROM), such as flash ROM, random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM), mass storage, such as a hard disk or solid state disk, etc. As shown, the memory 1030 can include software 1040 and / or firmware 1050. The memory 1030 can include suitably configured program code to be executed by one or more processors 1020 to implement the functions described above for time synchronization, as described with respect to FIGS. 6 - 8.

[0114] It should be understood that the structure shown in FIG. 10 is only schematic and that the wireless communication device 1000 may actually include additional components not shown, such as additional interfaces, such as a dedicated management interface, or additional processors, for the sake of clarity. It should also be understood that the memory 1030 may include additional program code for implementing known functions of the UE.

[0115] According to some embodiments, a computer program may also be provided in the form of a physical medium storing, for example, program code and / or other data to be stored in the memory 1030, or by making the program code available for download or streaming in order to implement the functions of the wireless communication device 1000.

[0116] Next, further details applicable to the embodiments described above are explained in the following sections.

[0117] Section 1: RACH Procedure Using Extended PRACH for Time Synchronization In this section, the RACH procedure is used for the gNB to send timing advance related information to the UE, where the PRACH used in the RACH procedure is extended for more accurate uplink timing estimation at the gNB.

[0118] The RACH procedure includes all variants, including 4-step RACH and 2-step RACH, contention-free based RACH and contention-based RACH. The timing advance (TA) related information can be absolute timing advance and incremental timing advance. The TA related information is carried in the random access response (RAR) message, where the RAR message format includes all variants for the corresponding RACH procedure, i.e., RAR for the 4-step RACH procedure, fallbackRAR and successRAR MAC subPDUs for the 2-step RACH.

[0119] The extended PRACH is specifically designated for improved timing detection and is different from the PRACH used for normal data communication, such as random access and normal timing detection. In a preferred embodiment, the extended PRACH occupies a larger bandwidth than the PRACH for normal data communication for a given value of the PUSCH SCS.

[0120] In the extended PRACH for timing detection, the timing information generated by the gNB can be signaled with a smaller or finer granularity so as to achieve improved timing accuracy. For example, when the extended PRACH is used in the uplink, the timing advance command is related to the granularity g1, where g1 < g0. Here, g0 is the granularity defined for the normal transmission timing adjustment of PUCCH / PUSCH / SRS. For the 2μ * 15kHz uplink SCS, the existing timing advance command granularity g0 is g0 = 16 * 64 / 2μ in NR Rel-15 / Rel-16. In contrast, for g1 < g0, exemplary values of g1 include g1 = K / 2μ, where the integer K is preferably a power of 2 value and K < 16 * 64. Exemplary values of K include K = {8 * 64, 4 * 64, 2 * 64, 64, 32, 16}.

[0121] The timing advance value carried in the RAR is denoted as TA. The absolute timing advance value is NTA = TA * g1. The propagation delay between the gNB and the UE is estimated as TIFF0007700262000006.tif10170.

[0122] Tc is the basic timing unit defined in TS38.211, and T c = 1 / (Δf max · N f ) and here, Δfmax = 480 * 103Hz and Nf = 4096.

[0123] Section 1-1: Extended RACH procedure for common PRACH resources: Optionally, the RACH procedure used for time synchronization purposes is the same RACH as for initial attachment and uses a common PRACH resource shared by all UEs in the cell.

[0124] Optionally, the RACH configuration is cell-specific and common to all UEs in the cell, i.e., the upper layer configuration is provided by RACH-ConfigCommon for 4-step RACH and by RACH-ConfigCommonTwoStepRA in MsgA-ConfigCommon for 2-step RACH. In this way, the RACH resource overhead is minimized to support more accurate timing synchronization in TSN.

[0125] Optionally, only TSN usage can use some preambles, and different preambles are used to distinguish TSN usage from non-TSN usage. Further, the same UE can access both the preambles reserved for TSN usage and those reserved for non-TSN usage. The UE uses the preamble reserved for TSN usage if the upper layer in the UE indicates that, for example, TSN time synchronization or the TSN protocol has been started in its software stack. Otherwise, the UE uses the preamble reserved for non-TSN usage. In this variant, which preamble is used for TSN usage is implicit. For example, the UE selects (depending on the UE implementation) the preamble that gives better timing estimation (e.g., longer length, larger bandwidth, etc.) in the gNB, or the network indicates so in the non-access stratum (NAS) message.

[0126] Optionally, the gNB divides the common PRACH resources of one cell into two sets, e.g., set A and set B. Set A is reserved for TSN usage and set B is reserved for non-TSN usage. The gNB simply sets set A for one set of UEs in the cell (which require accurate reference time distribution for TSN) and set B for another set of UEs in the cell (which do not require accurate reference time distribution).

[0127] Optionally, the RACH configuration is cell-specific and common to all UEs in the cell, but the PRACH resources are explicitly and separately configured, for example, for propagation delay compensation used in accurate timing distribution for the purpose of time synchronization in the TSN. In this way, a more flexible PRACH / MsgA configuration can be set for more accurate time synchronization in the TSN.

[0128] To implement this change in the specification, as an example, a separate RRC field / IE, namely RACH-ConfigCommonSync for the 4-step RACH, is set and provided by RACH-ConfigCommonTwoStepRASync in MsgA-ConfigCommonSync for the 2-step RACH. TIFF0007700262000007.tif107170

[0129] Optionally, the PRACH is triggered by a downlink signal (e.g., DCI transmitted in DCI or PDCCH order), and the PRACH resources are cell-common.

[0130] Section 1-2: Dedicated PRACH resources with extended PRACH: Optionally, the RACH procedure used for time synchronization purposes is triggered when the radio link is already established, i.e., not the same RACH as in the initial attachment, and the UE is in the RRC_CONNECTED state. In a preferred embodiment, the RACH procedure using the extended PRACH is triggered by the PDCCH. The DCI format carried by the PDCCH is extended for uplink timing detection and includes a field indicating the (one or more) PRACH occasion(s) configured for the extended PRACH, which is different from the PRACH for initial access.

[0131] Optionally, the RACH procedure using the extended PRACH is triggered periodically. For example, the PRACH transmission can be similar to the configured grant-based PUSCH transmission.

[0132] Optionally, the extended PRACH is not provided by cell-specific signaling shared by all UEs in the cell. Instead, the extended PRACH is provided by UE-specific signaling. For example, the RRC configuration is sent in a UE-specific RRC message, such as RACH-ConfigDedicated. Alternatively, the extended PRACH is provided by group-specific signaling. For example, the RRC configuration RACH-ConfigDedicated is sent to and shared by a group of TSN UEs.

[0133] An example regarding the dedicated PRACH configuration for TSN in the RACH-ConfigDedicated IE is provided below. TIFF0007700262000008.tif117170

[0134] Section 1-3: PRACH mask for filtering PRACH resources for clock synchronization: Optionally, when dedicated PRACH resources are configured, a new RACH mask index value can be defined for clock synchronization in TSN compared to NR Rel-16.

[0135] The PRACH mask index can be signaled by the DCI format when the PDCCH order is used to trigger PRACH transmission for clock synchronization. For example, the 4-bit "PRACH mask index" field in DCI format 1_0.

[0136] Let J be the PRACH occasion index. The variable J is an integer with a value starting from 1. The maximum value of the variable J depends on the time / frequency / format settings of the PRACH. As an example, as shown in Table 4 below, two new sets of allowed PRACH occasions for SSB can be defined via the previously reserved values 11 and 12 of the PRACH mask index. TIFF0007700262000009.tif104170

[0137] Optionally, a PRACH mask is introduced to determine the common PRACH resources for clock synchronization.

[0138] Section 1-4: PRACH configuration with time domain correction for clock synchronization: Optionally, the PRACH configuration for clock synchronization is based on the PRACH configuration for clock synchronization but with a configurable time domain correction.

[0139] The configuration is performed by the RRC and the correction includes, for example, the following.

[0140] For the clock synchronization of the UE with the network node (e.g., gNB), the following applies. - When the upper layer parameter prach-ConfigurationPeriodScalingSync is set, the variable x used in n_“f” “mod”x=y in Tables 6.3.3.2-2 to 6.3.3.2-4 shall be replaced by x_“sync”, where x_“sync” = αx and α is given by the upper layer parameter prach-ConfigurationPeriodScalingSync. - When the upper layer parameter prach-ConfigurationFrameOffsetSync is set, the variable y used in n_“f” “mod”x=y in Tables 6.3.3.2-2 to 6.3.3.2-4 shall be replaced by y_“sync”=(y+Δy)“mod”x, where Δy is given by the upper layer parameter prach-ConfigurationFrameOffsetSync, and x is the value used in n_“f” modx=y. - When the upper layer parameter prach-ConfigurationSOffsetSync is set, the subframe number s_“n” from Tables 6.3.3.2-2 to 6.3.3.2-3 and the slot number s_“n” from Table 6.3.3.2-4 shall be replaced by (s_“n”+Δs)“mod”L, where Δs∈{0,1,…,L-1} is given by the upper layer parameter prach-ConfigurationSOffsetSync, and L is the number of subframes in a frame when using Tables 6.3.3.2-2 to 6.3.3.2-3, and the number of slots in a frame for a 60 kHz subcarrier spacing when using Table 6.3.3.2-4.

[0141] Upper layer (e.g., RRC) parameters (prach-ConfigurationPeriodScalingSync, prach-ConfigurationFrameOffsetSync, prach-ConfigurationSOffsetSync) may be part of IE RACH-ConfigGeneric or RACH-ConfigGenericTwoStepRA-r16.

[0142] The configuration can be sent to the UE in cell-specific format, i.e., the parameters are the same for all UEs in the same cell. For example, the parameters can be included in the information element RACH-ConfigCommon for 4-step RACH and / or in RACH-ConfigCommonTwoStepRA for 2-step RACH. Alternatively, these higher layer parameters can be configured for specific TSN UEs with different values and can be transmitted, for example, in RACH-ConfigDedicated.

[0143] Exemplary configurations of these parameters are shown below. TIFF0007700262000010.tif170170

[0144] Section 1-5: Higher priority PRACH configuration for clock synchronization: Higher priority PRACH configuration: For time synchronization in TSN, a higher power ramping step and / or a smaller backoff time can be used. An example of how to implement this in RRC is shown below. A separate IE RA-PrioritizationTimeSync with more code points can be used. TIFF0007700262000011.tif76170

[0145] The new IE can be used in the IE that configures the RACH resources, e.g., RACH-ConfigCommon for 4-step RA, RACH-ConfigCommonTwoStepRA for 2-step RA, 2-step CFRA or 4-step CFRA. An example is shown below. TIFF0007700262000012.tif80170

[0146] Section 2: Other uplink reference signal (other than PRACH)-based procedures for time synchronization In this section, the procedure uses uplink reference signals (i.e., not PRACH) on the uplink for the gNB to estimate uplink timing. In one example, the uplink reference signal (RS) is an extended SRS. Other examples of uplink reference signals include demodulation reference signals (DMRS), phase-tracking RS (PTRS). The following description assumes SRS, but DMRS and PTRS can be used in a similar procedure.

[0147] Section 2-1: Aperiodic SRS-based procedure: The SRS can be an aperiodic SRS (A-SRS). For each time instance, PD estimation is required and the following procedure is applied. - Step (a): The gNB sends a downlink signal to trigger an aperiodic SRS transmission on the uplink. - Step (b): The triggered aperiodic SRS is sent from the UE to the gNB. - Step (c): The gNB performs uplink timing detection based on the transmitted A-SRS and derives timing information. - Step (d): The gNB sends the timing information to the UE, either with a timing advance adjustment MAC CE (e.g., a time synchronization command (TSC) MAC CE) or an RRC message containing an accurate reference time with a pre-compensated propagation delay.

[0148] If PD estimation is required repeatedly (e.g., to refresh PD estimation from time to time), the above procedure is repeatedly applied, including the downlink signal to trigger A-SRS, as shown in Figure 11. Preferably, the gNB configures this A-SRS to be a broadband SRS, which is defined for time synchronization purposes.

[0149] The following is an example regarding the SRS resource configuration for time synchronization purposes in the RRC specification. In the first example, a specific SRS resource set for time synchronization is configured. TIFF0007700262000013.tif166170TIFF0007700262000014.tif255170TIFF0007700262000015.tif75170

[0150] Section 2-2: Semi-Persistent SRS-Based Procedure: Alternatively, the SRS can be a semi-persistent SRS (SP-SRS). The SP-SRS transmission periodicity is a function of the PD (propagation delay) estimation refresh periodicity. The PD refresh periodicity can be a function of the periodicity of the accurate reference time refresh from the gNB to the UE and / or the periodicity of the gPTP message refresh from the TSN master clock to the TSN slave clock. Further / Alternatively, the PD estimation refresh periodicity can be set independently of the upper layer reference time refresh.

[0151] The SP-SRS transmission has an offset with respect to the PD refresh periodicity.

[0152] For example, the SP-SRS periodicity is set to be the same as the PD refresh periodicity, and the offset is applied such that the SP-SRS is sent in advance so that the estimated PD value can complete the PD estimation procedure before being required by the TSN application, for example, to timestamp incoming / outgoing gPTP messages.

[0153] In the case of SP-SRS, the SRS transmission is sent periodically when triggered.

[0154] Thus, in one embodiment, as shown in FIG. 12, the procedure is performed as follows. - Step (a): The gNB sends an RRC configuration for the SP-SRS, including the time domain parameters and frequency domain parameters of the SP-SRS. - Step (b): The gNB sends a downlink signal to trigger the SP-SRS transmission on the uplink. - Step (c): The triggered SP-SRS is sent from the UE to the gNB with the configured periodicity and offset. - Step (d): For each time instance, PD estimation is required. - The gNB performs uplink timing detection based on the transmitted SP-SRS and derives timing information. - The gNB sends the UE timing information with either a timing advance adjustment MAC CE (e.g., a time-sensitive communication (TSC) MAC CE) or an RRC message containing an accurate reference time with a pre-compensated propagation delay.

[0155] In a variant of the embodiment described with reference to FIG. 12, furthermore, the periodic SRS transmission is only effective for a configurable period. The period can be set as an absolute time value such as 5 ms, 10 ms, etc., or as a number of SRS periods such as 10 SRS periods, 20 SRS periods, etc. In a follow-up network implementation example, the effective period is set such that the effective period extends at least until the time when an accurate reference time (with compensated PD) is required at the UE for TSN application. In another network implementation example, the duration of the effective period is a function of UL channel conditions, time synchronization requirements, etc. For example, the effective period should be longer for worse UL channel conditions or stringent synchronization requirements since it is expected that the estimation will be better with more SRS transmissions.

[0156] Thus, as shown in FIG. 13, the procedure is performed as follows. - Step (a): The gNB sends RRC configuration for the SP-SRS, including the time-domain parameters and frequency-domain parameters of the SP-SRS, and furthermore, the effective period. - Step (b): The gNB sends a downlink signal to trigger SP-SRS transmission on the uplink. - Step (c): The triggered SP-SRS is sent from the UE to the gNB with the configured periodicity, offset, and validity period. - Step (d): For each time instance, PD estimation is required. - The gNB performs uplink timing detection based on the transmitted SP-SRS and derives timing information. - The gNB sends the UE timing information with either a timing advance adjustment MAC CE (e.g., a time-sensitive communication (TSC) MAC CE) or an RRC message containing an accurate reference time with a pre-compensated propagation delay.

[0157] In another variation of the embodiment described with reference to FIG. 12, SRS transmission opportunities are temporally separated by a cycle length (e.g., 50 ms, 100 ms) as shown in FIG. 14. At each SRS transmission opportunity, the SRS is repeatedly transmitted within a validity period (or several repetitions). When the gNB sends a DL signal to trigger the SRS, the SRS transmission opportunities occur periodically until another DL signal is sent by the gNB to end the SRS transmission. At the end of an SRS transmission opportunity, time synchronization between the gNB and the UE can be estimated and updated (i.e., time synchronization refresh) using all SRS repetitions within one SRS transmission opportunity.

[0158] Note that in the embodiments described above, other types of parameters may be used to achieve similar or the same effects. For example, the validity period can be equivalently provided by the number of SRS instances to be transmitted in one transmission opportunity, e.g., in the example of FIG. 13, for each transmission opportunity, by 4 SRS instances.

[0159] Section 2-3: Periodic SRS-based Procedures Alternatively, the SRS can be periodic SRS (P-SRS). The P-SRS transmission periodicity is a function of the PD (propagation delay) estimation refresh periodicity. The PD refresh periodicity can be set in a similar manner as for semi-persistent SRS. The P-SRS transmission has an offset with respect to the PD refresh periodicity. For example, the P-SRS periodicity is set to be the same as the PD refresh periodicity, and the offset is applied such that the P-SRS is sent in advance so that the PD estimation procedure can be completed before the estimated PD value is required by TSN application.

[0160] In the case of P-SRS, the SRS transmission is sent periodically after the RRC configuration of the periodic SRS is provided to the UE. Thus, as shown in Figure 15, the procedure is performed as follows. - Step (a): The gNB sends the RRC configuration for periodic SRS transmission. - Step (b): After receiving the RRC configuration, the UE starts to send the P-SRS according to the configuration provided by the gNB, including the periodicity and the offset. - Step (c): For each time instance, PD estimation is required, - The gNB performs uplink timing detection based on the sent P-SRS, derives the timing information, - The gNB sends the timing information to the UE, with either a timing advance adjustment MAC CE (e.g., time-sensitive communication (TSC) MAC CE) or an RRC message containing an accurate reference time with a pre-compensated propagation delay.

[0161] As technology progresses, it will be apparent to those skilled in the art that the inventive concept can be implemented in various ways. The embodiments described above are provided for purposes of illustration rather than limitation, and it should be understood that modifications and variations can be made without departing from the scope of the present disclosure, as will be readily understood by those skilled in the art. Such modifications and variations are considered to be within the scope of the present disclosure and the appended claims. The protection scope of the present disclosure is defined by the appended claims.

[0162] Some exemplary embodiments of the present disclosure are as follows.

[0163] Embodiment 1: A method for time synchronization between an access node and a wireless communication device in a wireless communication network, the following steps being performed at the access node, namely, a) Receiving, from a wireless communication device, a physical random access channel (PRACH) preamble for extending timing detection, wherein the transmission of the preamble for extending timing detection occupies more or separate physical resources compared to that without the purpose of extending timing detection, receiving a physical random access channel (PRACH) preamble for extending timing detection; b) Deriving timing relationship information based on the preamble for extending timing detection; c) Sending to the wireless communication device the timing relationship information or the clock time for the wireless communication device determined based on the timing relationship information. A method comprising the above.

[0164] Embodiment 2: The method according to claim 1, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop integrated device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0165] Embodiment 3: The method according to claim 2, wherein the timing relationship information is at least one of an absolute timing advance (TA), TA adjustment, and propagation delay (PD).

[0166] Embodiment 4: The method according to claim 3, wherein the timing relationship information is included in a TA command signaled with a granularity smaller than or finer than the granularity for normal transmission timing adjustment of a physical uplink control channel (PUCCH) / physical uplink shared channel (PUSCH) / sounding reference signal (SRS).

[0167] Embodiment 5: The method according to claim 3, wherein the physical resources for transmitting a preamble for extending timing detection are shared by all wireless devices in a cell associated with an access node.

[0168] Embodiment 6: The method according to claim 5, wherein the radio access channel (RACH) configuration is cell-specific and common to all wireless communication devices in a cell associated with an access node.

[0169] Embodiment 7: The method according to claim 3, wherein, unlike for use cases of a non-time sensitive network (TSN), a part of the PRACH resources in a cell associated with an access node is reserved for transmitting a preamble for extending timing detection.

[0170] Embodiment 8: The method according to claim 3, wherein the wireless communication device is in an RRC connected state and, prior to step a), a physical downlink control channel (PDCCH) including a downlink control information (DCI) format that specifies which (one or more) PRACH occasions are configured for extending timing detection triggers a radio access channel procedure, and thus the wireless communication device transmits a preamble for extending timing detection on dedicated PRACH resources, including triggering a radio access channel procedure.

[0171] Embodiment 9: The method according to claim 8, wherein the dedicated PRACH resource is shared by all wireless communication devices in a cell associated with the access node or is allowed to be used by a group of wireless devices.

[0172] Embodiment 10: The method according to claim 8 or 9, wherein the PRACH mask signaled by DCI is used to extend timing detection, filter a dedicated PRACH resource, or determine a common PRACH resource.

[0173] Embodiment 11: The method according to any one of claims 1 to 10, wherein the PRACH configuration for clock synchronization has configurable time domain corrections.

[0174] Embodiment 12: The method according to any one of claims 1 to 11, wherein a higher power ramping step and / or a smaller backoff time are used to extend timing detection.

[0175] Embodiment 13: A method for time synchronization between an access node and a wireless communication device in a wireless communication network, the following steps being performed at the access node, namely, a) receiving an uplink (UL) reference signal (RS) from the wireless communication device; b) deriving timing relationship information based on the UL RS; c) sending the timing relationship information or the clock time for the wireless communication device determined based on the timing relationship information to the wireless communication device and including the method.

[0176] Embodiment 14: The method according to claim 13, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop embedded device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0177] Embodiment 15: The method according to claim 14, wherein the UL RS is selected from the group consisting of a wideband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0178] Embodiment 16: The method according to claim 14 or 15, wherein the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0179] Embodiment 17: The method according to claim 13, further comprising sending a downlink (DL) signal to the wireless communication device to trigger UL RS transmission before step a).

[0180] Embodiment 18: A method for time synchronization between an access node of a wireless communication network and a wireless communication device, the method comprising the following steps performed at the access node, namely, a) sending a setting to the wireless communication device, according to which the wireless communication device performs a plurality of UL RS transmissions; b) each time receiving one UL RS from the wireless communication device or receiving a predetermined number of UL RSs from the wireless communication device, deriving respective timing relationship information based on the received UL RS(s), and sending the respective timing relationship information or a clock time for the wireless communication device determined based on the respective timing relationship information to the wireless communication device; The method includes the above steps.

[0181] Embodiment 19: The method according to claim 18, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop embedded device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0182] Embodiment 20: The method according to claim 19, wherein the UL RS is selected from the group consisting of a wideband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0183] Embodiment 21: The method according to claim 19 or 20, wherein the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0184] Embodiment 22: The method according to claim 18, wherein the setting is an RRC setting that specifies a periodicity of a plurality of UL RS transmissions and an offset of the periodicity of the plurality of UL RS transmissions with respect to a propagation delay (PD) refresh periodicity.

[0185] Embodiment 23: The method according to claim 18, wherein the setting is an RRC setting that specifies a periodicity of a plurality of UL RS transmissions, a validity period of the plurality of UL RS transmissions, and an offset of the periodicity of the plurality of UL RS transmissions with respect to a propagation delay (PD) refresh periodicity.

[0186] Embodiment 24: The method according to claim 22 or 23, further comprising triggering a plurality of UL RS transmissions by sending a downlink (DL) signal to the wireless communication device before step b).

[0187] Embodiment 25: - at least one processor; - a memory including program code executable by the at least one processor An access node comprising: - An access node that causes at least one processor to execute program code to cause the access node to perform the method according to any one of claims 1 to 24.

[0188] Embodiment 26: A computer program product embodied on a computer-readable storage medium and comprising program code to be executed by at least one processor of an access node, whereby execution of the program code causes the access node to perform the method according to any one of claims 1 to 24.

[0189] Embodiment 27: A method for time synchronization between an access node and a wireless communication device in a wireless communication network, the method comprising the following steps performed at the wireless communication device, namely: a) Transmitting, to an access node, a physical random access channel (PRACH) preamble for extending timing detection, wherein transmitting the preamble for extending timing detection occupies more or different physical resources compared to transmitting a preamble without the purpose of extending timing detection; b) Receiving, from the access node, timing relationship information derived based on the preamble for extending timing detection, or a clock time for the wireless communication device determined based on the timing relationship information. A method comprising the above.

[0190] Embodiment 28: The method according to claim 27, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop embedded device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0191] Embodiment 29: The method according to claim 28, wherein the timing relationship information is at least one of absolute timing advance (TA), TA adjustment, and propagation delay (PD).

[0192] Embodiment 30: The method according to claim 28 or 29, wherein the timing relationship information is included in a TA command signaled with a granularity smaller than or finer than the granularity for normal transmission timing adjustment of a physical uplink control channel (PUCCH) / physical uplink shared channel (PUSCH) / sounding reference signal (SRS).

[0193] Embodiment 31: The method according to claim 28 or 29, wherein the physical resources for transmitting a preamble for extending timing detection are shared by all radio devices in a cell associated with an access node.

[0194] Embodiment 32: The method according to claim 28 or 29, wherein a preamble for extending timing detection is different from that for use cases of a non-time sensitive network (TSN), and a part of the PRACH resources in a cell associated with an access node is reserved for transmitting a preamble for extending timing detection.

[0195] Embodiment 33: The method according to claim 28 or 29, including receiving a PDCCH order including a downlink control information (DCI) format that specifies which (one or more) PRACH occasions are set for extending timing detection before step a), so that the radio communication device receives a PDCCH order for transmitting a preamble for extending timing detection by dedicated PRACH resources.

[0196] Embodiment 34: The method according to claim 33, wherein the dedicated PRACH resource is shared by all wireless communication devices in the cell associated with the access node or is allowed to be used by a group of wireless devices.

[0197] Embodiment 35: A method for time synchronization between an access node and a wireless communication device in a wireless communication network, the method comprising the following steps performed at the wireless communication device, namely, a) transmitting an uplink (UL) reference signal (RS) to the access node; and b) receiving, from the access node, timing relationship information derived based on the UL RS or the clock time for the wireless communication device determined based on the timing relationship information. A method comprising the above.

[0198] Embodiment 36: The method according to claim 35, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop embedded device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0199] Embodiment 37: The method according to claim 36, wherein the UL RS is selected from the group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0200] Embodiment 38: The method according to claim 36 or 37, wherein the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0201] Embodiment 39: The method according to claim 36, further comprising receiving, from the access node, a downlink (DL) signal for triggering the UL RS transmission before step a).

[0202] Embodiment 40: A method for time synchronization between an access node and a wireless communication device in a wireless communication network, the following steps being performed in the wireless communication device, namely, a) receiving, from an access node, a configuration according to which the wireless communication device performs a plurality of UL RS transmissions; b) after transmitting one UL RS to the access node or transmitting a predetermined number of UL RSs to the access node, each time receiving, from the access node, respective timing relationship information derived based on the (one or more) transmitted UL RSs, or a clock time for the wireless communication device determined based on the respective timing relationship information; A method comprising the above.

[0203] Embodiment 41: The method according to claim 40, wherein the access node is an eNB or a gNB, and the wireless communication device is selected from the group consisting of a user equipment (UE), a tablet, a mobile terminal, a smartphone, a laptop embedded device, a laptop-mounted device, and an Internet of Things (IoT) device.

[0204] Embodiment 42: The method according to claim 41, wherein the UL RS is selected from the group consisting of a broadband or extended sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0205] Embodiment 43: The method according to claim 41 or 42, wherein the timing relationship information is at least one of an absolute timing advance, a TA adjustment, and a propagation delay.

[0206] Embodiment 44: The method according to claim 40, wherein the configuration is an RRC configuration specifying a periodicity of a plurality of UL RS transmissions and an offset of the periodicity of the plurality of UL RS transmissions with respect to a propagation delay (PD) refresh periodicity.

[0207] Embodiment 45: The method according to claim 40, wherein the configuration is an RRC configuration that specifies the periodicity of a plurality of UL RS transmissions, the validity period for the plurality of UL RS transmissions, and the offset for the periodicity of the plurality of UL RS transmissions with respect to the propagation delay (PD) refresh periodicity.

[0208] Embodiment 46: The method according to claim 44 or 45, further comprising receiving, from an access node, a downlink (DL) signal for triggering a plurality of UL RS transmissions before step b).

[0209] Embodiment 47: - at least one processor; - a memory including program code executable by the at least one processor A wireless communication device comprising: - whereby execution of the program code by the at least one processor causes the wireless communication device to perform the method according to any one of claims 27 to 46.

[0210] Embodiment 48: A computer program product embodied on a computer-readable storage medium and comprising program code to be executed by at least one processor of an access node, whereby execution of the program code causes the wireless communication device to perform the method according to any one of claims 27 to 46.

[0211] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are contemplated within the scope of the concepts disclosed herein.

Claims

1. A method performed by a wireless communication device (101), the method comprising: transmitting, to an access node, a signal for extended uplink timing estimation (610, 720), wherein the signal occupies more or separate physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation; receiving, from the access node, a message including clock time (620, 730) in response to transmitting the signal for extended uplink timing estimation; A method comprising the above.

2. A method performed by a wireless communication device (101), the method comprising: transmitting, to an access node, a signal for extended uplink timing estimation (610, 720), wherein the signal occupies more or separate physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation; receiving, from the access node, a message including timing relation information or clock time (620, 730) in response to transmitting the signal for extended uplink timing estimation; Including, wherein the signal for extended uplink timing estimation is a physical random access channel (PRACH) preamble for extended uplink timing estimation, and the PRACH preamble for extended uplink timing estimation occupies more or separate physical resources compared to a PRACH preamble for purposes other than extended uplink timing estimation.

3. The method according to claim 2, wherein the message including the timing relation information or the clock time is a random access response.

4. The method according to claim 2 or 3, wherein the PRACH preamble has a bandwidth larger than 12 physical resource blocks (PRBs), and the PRACH preamble for purposes other than extended uplink timing estimation is 12 PRBs.

5. Each PRB is 15.2 μ ·12 kilohertz bandwidth, and 15.2 μ kilohertz is the subcarrier spacing of each cell on which the PRACH preamble is transmitted, according to the method of claim 4.

6. The message includes the timing relation information, The timing relation information includes at least one of an absolute timing advance, a timing advance adjustment, and a propagation delay. The timing relation information includes a timing advance command, the timing advance command has a granularity of K / 2μ, μ is an integer greater than 0 or equal to 0, 15.2 μ Kilohertz is the subcarrier spacing of each cell on which the PRACH preamble is transmitted, and K is less than 1,024. The method according to any one of claims 2 to 5.

7. The method according to claim 6, wherein K is a value that is a power of 2, or K is 512, 256, 128, 64, 32, or 16.

8. The PRACH preamble is transmitted on a PRACH resource from a common set of PRACH resources for all wireless communication devices in each cell on which the PRACH preamble is transmitted. Transmitting the PRACH preamble (610) is cell-specific and includes transmitting the PRACH preamble (610) according to a RACH configuration that is common to all wireless communication devices in each cell on which the PRACH preamble is transmitted. The method according to any one of claims 2 to 7.

9. The PRACH preamble is one of a first set of PRACH preambles dedicated to time synchronization, and the first set of PRACH preambles is different from a second set of PRACH preambles defined for the cell for random access for purposes other than extended uplink timing estimation. The wireless communication device (101) transmits the PRACH preamble from the first set of PRACH preambles in response to an indication from a higher layer that the random access procedure is for TSN time synchronization, or an indication that the TSN protocol has been initiated in the wireless communication device (101). The method according to claim 8.

10. Transmitting the PRACH preamble (610) is triggered by a downlink signal. Transmitting the PRACH preamble (610) is performed while the wireless communication device (101) is in a connected state. Transmitting the PRACH preamble (610) is triggered by downlink control information (DCI) received from the access node while the wireless communication device (101) is in the connected state. The DCI includes a field indicating one or more PRACH occasions configured for extended uplink timing estimation. The method according to any one of claims 2 to 9.

11. The method according to claim 10, wherein transmitting the PRACH preamble (610) while the wireless communication device (101) is in the connected state is in accordance with settings received via device-specific or group-specific signaling.

12. The PRACH preamble is transmitted on a dedicated PRACH resource, and a PRACH mask index value defined for clock synchronization in a time-sensitive network (TSN) is used for the dedicated PRACH resource, or transmitting the PRACH preamble (610) includes transmitting the PRACH preamble (610) according to a PRACH setting for extended uplink timing estimation, and the PRACH setting for extended uplink timing estimation is the same as the PRACH setting for purposes other than extended uplink timing estimation, but with a configurable time-domain correction, or transmitting the PRACH preamble (610) a first power ramping step size that is larger than a second power ramping step size used for transmitting a PRACH preamble for purposes other than extended uplink timing estimation, a first backoff time that is smaller than a second backoff time used for transmitting a PRACH preamble for purposes other than extended uplink timing estimation, or both the first power ramping step size and the first backoff time The method according to any one of claims 2 to 7 or 11, including transmitting the PRACH preamble (610) according to.

13. A method performed by a wireless communication device (101), the method comprising: transmitting (610, 720) a signal for extended uplink timing estimation to an access node, the signal occupying more or separate physical resources compared to a corresponding signal transmitted for purposes other than extended uplink timing estimation; transmitting (610, 720) a signal for extended uplink timing estimation; receiving (620, 730) a message including timing relationship information or clock time from the access node in response to transmitting the signal for extended uplink timing estimation; including The signal for extended uplink timing estimation includes one or more uplink reference signals for extended uplink timing estimation, and the one or more uplink reference signals for extended uplink timing estimation occupy more or separate physical resources compared to the corresponding one or more reference signals transmitted for purposes other than extended uplink timing estimation. The one or more uplink reference signals for extended timing estimation include aperiodic, semi-persistent, or periodic phase-tracking reference signals (PTRS). A method. **Claim 14** The one or more uplink reference signals for extended timing estimation include a periodic reference signal. The method according to claim 13, wherein the periodic reference signal has a bandwidth larger than the bandwidth of the corresponding periodic reference signal transmitted for purposes other than extended uplink timing estimation. **Claim 15** The one or more uplink reference signals for extended timing estimation include a semi-persistent reference signal. The method according to claim 14, wherein the periodicity of the semi-persistent reference signal is a function of the propagation delay estimation refresh periodicity. **Claim 16** The propagation delay estimation refresh periodicity is a function of an accurate reference time refresh from the access node (105) to the wireless communication device (101), a periodicity of a general-purpose high-precision time protocol (gPTP) message refresh from a time-sensitive network (TSN) master clock to a related TSN slave clock, or both, or The propagation delay estimation refresh periodicity is set independently of the upper layer reference time refresh, or The method according to claim 15, wherein the semi-persistent reference signal has an offset value with respect to the propagation delay estimation refresh periodicity. **Claim 17** The method according to claim 15 or 16, wherein the semi-persistent reference signal has a related validity period. **Claim 18** The method according to claim 13, wherein the one or more uplink reference signals for extended timing estimation include a periodic reference signal. **Claim 19** The periodicity of the periodic reference signal is a function of the propagation delay estimation refresh periodicity, or The method according to any one of claims 15 to 17, wherein the semi-persistent reference signal has an offset value with respect to the propagation delay estimation refresh periodicity. **Claim 20** The method according to any one of claims 13 to 19, wherein the message is a timing advance adjustment medium access control (MAC) control element (CE) or a radio resource control (RRC) message.

21. A wireless communication device (101) comprising a wireless interface (1010) and one or more processors (1020) associated with the wireless interface (1010), wherein the one or more processors (1020) cause the wireless communication device (101) to transmit a physical random access channel (PRACH) preamble for extended uplink timing estimation (610), wherein the PRACH preamble for extended uplink timing estimation occupies more or separate physical resources compared to a PRACH preamble for purposes other than extended uplink timing estimation; and in response to transmitting the PRACH preamble, receive a random access response from the access node that includes timing relationship information or clock time (620). A wireless communication device (101) configured to perform the above.

22. A method performed by an access node (105), the method comprising: receiving a signal for extended uplink timing estimation from a wireless communication device (101) (310), wherein the signal for extended uplink timing estimation occupies more or separate physical resources compared to a corresponding signal for purposes other than extended uplink timing estimation; deriving timing relationship information based on the signal for extended uplink timing estimation (320); and in response to receiving the signal for extended uplink timing estimation, transmitting a message including clock time to the wireless communication device (101) (330). A method including the above.

23. An access node (105) comprising one or more processors (930), Receiving (310) a physical random access channel (PRACH) preamble from a wireless communication device (101) for extended uplink timing estimation, wherein the PRACH preamble for extended uplink timing estimation occupies more or separate physical resources as compared to a PRACH preamble for purposes other than extended uplink timing estimation, and receiving (310) the physical random access channel (PRACH) preamble for extended uplink timing estimation Deriving (320) timing relationship information based on the PRACH preamble for extended uplink timing estimation In response to receiving the PRACH preamble, transmitting (330) a random access response including timing relationship information or clock time to the wireless communication device (101) An access node (105) configured to cause the above to be performed.

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