WO2021033114A1

WO2021033114A1 - Timing advance enhancement

Info

Publication number: WO2021033114A1
Application number: PCT/IB2020/057694
Authority: WO
Inventors: Bikramjit Singh; Yufei Blankenship; John Walter Diachina
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-08-16
Filing date: 2020-08-14
Publication date: 2021-02-25

Abstract

A method performed by a node (e.g., a gNB) is provided. The method includes: sending one or more timing advance (TA) commands to a user equipment (UE). The one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity. The second granularity is smaller than the first granularity.

Description

TIMING ADVANCE ENHANCEMENT RELATED APPLICATIONS

[001] This application claims priority to U.S. Serial No. 62/887,992 filed August 16,

2019, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[002] Disclosed are embodiments related to time synchronization and clock distribution, for instance, with respect to a Time Sensitive Network (TSN).

BACKGROUND

[003] Fifth generation (5G) new radio (NR) can be implemented to support a TSN. For instance, 5G can be integrated in Ethernet-based industrial communication networks. Use cases could include, for example, factory automation networking or other Industrial Internet of Things (IIoT) applications.

[004] Third Generation Partnership Project (3GPP) Technical Specification (TS) 38.133 describes timing advance adjustments and delays, including a 3GPP Timing Advance (TA) command, which is utilized in cellular communication for uplink transmission synchronization. It is further classified as one of two types. A first type of command may be used at the beginning, for instance at connection setup, and provides an absolute timing parameter. This first type is communicated to a User Equipment (UE) using a Medium Access Control (MAC) Random Access Response (RAR) element. A second type may be used at connection setup. This second type may be understood as a relative timing correction sent to a UE using the MAC Control Element (CE). Corrections may be needed, for instance, when UEs move locations or due to multi-path delay in a changing environment.

[005] The downlink Propagation Delay (PD) can be estimated for a given UE by: (1) summing the TA value indicated by the RAR and all subsequent TA values sent using the MAC CE, and (2) taking some portion of the total TA value resulting from summation of all the TA values (e.g. 50% could be used assuming the downlink and uplink propagation delays are essentially the same). The propagation delay (PD) can be utilized to address time synchronization dynamics, for instance, for frame alignment at the node (e.g., gNB). 3GPP TS 38.133 (16.0.0) at Section 7.3 (“Timing Advance”) and 3GPP TS 36.213 (15.6.0) at Section 4.2 (“Timing Synchronization”) provide a description of TA related and synchronization procedures. [006] There remains a need for improved determination and communication of Timing

Advances.

SUMMARY

[007] According to embodiments, synchronization and timing offset processes and devices are provided. Such processes and devices may control Timing Advance procedures between nodes (e.g., between a gNB and UE) with improved granularity over existing technologies. The improved granularity can provide sufficient accuracy/certainty to enable TSN operation.

[008] According to embodiments, a node (e.g., gNB) implementation knows the uncertainty with which it can acquire uplink (UL) sync and can use that knowledge to determine a maximum uncertainty target it wants to allow when performing a TA procedure with a given UE. In certain aspects, the process may begin when the gNB triggers a TA procedure in which it indicates how much uncertainty the UE implementation is allowed when establishing downlink (DL) sync. For instance, the gNB may indicate the value of maximum uncertainty allowed for the TA procedure minus the value of the uncertainty with which it can acquire UL sync. If UE can accept the value indicated for the UE implementation, then it proceeds with the TA procedure. However, if the UE cannot accept the indicated value it can inform the gNB that the DL sync uncertainty target is too demanding but provide a best-case DL sync uncertainty that it can realize, in which case the gNB can then decide whether or not to proceed using the UE’s best case uncertainty. If the gNB decides not to proceed then the gNB has effectively determined that, due to an excessive uncertainty associated with performing a TA procedure, the overall uncertainty requirements (e.g. regarding an external TSN clock value) cannot be met as long as the UE remains in its current location and therefore informs the UE that any end stations (managed by the UE) that make use of the corresponding clock cannot operate with sufficient timing accuracy.

[009] Otherwise the gNB proceeds with the TA procedure. According to embodiments, this procedure supports legacy TA granularity values and TA values that are smaller than those of the legacy TA (e.g. granularity = 52 ns = 1.6*Ts). When the UE determines the value of the downlink PD it can, in some embodiments, assume that the downlink and uplink delays are symmetric and as such it can use ½ of the total TA (/.<?., resulting from the initial TA command plus subsequent TA commands as discussed herein) as the applicable downlink PD and can therefore increase the value of a received clock (e.g. the 5G system clock) using this PD value. The smaller the value the gNB determines for the maximum uncertainty allowed for the TA procedure and the smaller the value of the uncertainty with which it can acquire UL sync the smaller the value that can be indicated (by the TA command) for the maximum uncertainty the UE implementation is allowed when establishing DL sync. Aspects of the disclosure therefore allow for at least minimizing the component of the downlink PD uncertainty due to downlink sync detection in cases where there may be significant differences between downlink and uplink delays (/.<?., the greater the asymmetries of these delays the greater the uncertainty for the downlink PD value that results from the UE simply using ½ of the total TA as the downlink PD). Embodiments help to estimate PD, which in turn helps to measure an accurate clock at the UE side.

[0010] According to a first aspect, a method performed by a node (e.g., a gNB) is provided. The method includes sending one or more timing advance (TA) commands to a user equipment (UE). The one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and the second granularity is smaller than the first granularity.

[0011] According to a second aspect, a method performed by a user equipment (UE) is provided. The method includes receiving one or more timing advance (TA) command, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity. The method further includes determining a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing. The method further includes updating the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

[0012] According to a third aspect, a computer program is provided comprising instructions which when executed by processing circuitry causes the processing circuitry to perform the method of any one of the embodiments of the first or second aspects.

[0013] According to a fourth aspect, a carrier is provided containing the computer program of the third aspect, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium. [0014] According to a fifth aspect, a node (e.g., a gNB) is provided. The node is adapted to send one or more timing advance (TA) commands to a user equipment (UE). The one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and the second granularity is smaller than the first granularity.

[0015] According to a sixth aspect, a user equipment (UE) is provided. The UE is adapted to receive one or more timing advance (TA) command, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity. The UE is further adapted to determine a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing. The UE is further adapted to update the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

[0016] According to a seventh aspect, a node (e.g., a gNB) is provided. The node includes a sending unit configured to send one or more timing advance (TA) commands to a user equipment (UE). The one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and the second granularity is smaller than the first granularity.

[0017] According to a seventh aspect, a user equipment (UE) is provided. The UE includes a receiving unit configured to receive one or more timing advance (TA) command, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity. The UE further includes a determining unit configured to determine a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing. The UE further includes an updating unit configured to update the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing. [0018] These and other features of the present disclosure will become apparent to those skilled in the art from the following detailed description of the disclosure, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0020] FIG. 1 illustrates a system according to some embodiments.

[0021] FIGs. 2A and 2B illustrate messaging and timing offset according to some embodiments.

[0022] FIG. 2C illustrates a message format according to some embodiments.

[0023] FIG. 3 illustrates a flow diagram according to some embodiments.

[0024] FIG. 4 illustrates a flow diagram according to some embodiments.

[0025] FIG. 5 is a block diagram of a node (e.g., gNB or UE) according to some embodiments.

[0026] FIGs. 6A and 6B are diagrams showing functional modules of nodes according to some embodiments.

DETAIFED DESCRIPTION

[0027] A UE may receive a value for the 5G system clock (e.g. sourced by a GPS receiver that serves a 5G network and is made available to a gNB) that is subject to reduced accuracy due to downlink PD experienced when the gNB provides the UE with the 5G system clock. The UE can then mitigate the reduced accuracy by updating the value of that 5G system clock to reflect the downlink PD between the gNB and UE. The UE may thus realize a more finely synchronized value for that clock at the UE relative to the value for that same clock maintained by the 5G system. In other words, in order to estimate an accurate clock time or clock value the UE is required to add downlink PD to the clock time it receives from the gNB.

[0028] TA is utilized to synchronize uplink frame/slot timings (boundaries) at the gNB with respect to where downlink frame slot boundaries are transmitted by the gNB, such that the gNB receives the start of uplink System Frame Number (SFN) “X” at nominal point in time relative to when it transmits SFN X on the downlink. In LTE, TA is discrete and is sent with multiples of 16 Ts, which is a measure of the combined PD experienced over the downlink and uplink. Hence, the maximum frame timing (synchronization) error in either direction is 8 Ts with respect to where the gNB receives the start of uplink SFN X relative to the nominal point of its reception, where Ts = 32.5 ns is the basic time unit in LTE. Therefore, uplink timing error shall be within ±4*Ts assuming each direction introduces the same amount of synchronization error. Similarly, timing advance command is also discrete in NR and Tc = .509 ns is the basic time unit in NR. According to 3GPP TS 38.213, for NR the TA indicating granularity is 16 64 T_c/ 2^m, so the indicating error can be as large as ±8 64 T_c/ 2^m in the worst case. Additionally, Timing Advance adjustment accuracy is also defined in 3GPP TS 38.133. For Subcarrier Spacing (SCS) = 15 and 120 kHz, TA adjustment accuracy is half of TA granularity. For SCS = 30 and 60 kHz, TA adjustment accuracy is the same as TA granularity. Existing levels of granularity - and thus accuracy - may be unacceptable for certain TSN applications. While aspects of legacy TA may be used, there remains a need for enhancements in the TA implementation for better uplink/clock synchronization.

[0029] Aspects of this disclosure address the problem of clock inaccuracy/uncertainty inherent to methods for relaying one or more clocks (e.g. internal 5G system clock or external TSN clocks) via the 5G system to UEs supporting IIoT end devices. An inaccuracy of particular concern is a result of the radio frequency (RF) propagation delay that occurs when a gNB transmits a clock over the radio interface within a message (e.g. System Information Block (SIB) or Radio Resource Control (RRC) unicast based) wherein the propagation delay needs to be compensated to ensure the clock value received by the UE is as close as possible to the value of that clock in the corresponding source node (e.g. a gNB with knowledge of the 5G internal system clock or a TSN network node). According to embodiments, as a first step the 5G internal system clock is sent from a gNB to a UE and corrected by the UE to reflect the downlink PD, thereby allowing the UE and 5G core network (e.g., the User Plane Function (UPF) node) to have synchronized values for the 5G internal system clock. The availability of synchronized 5G internal system clocks at the UE and 5G core network then allows for an external TSN clock to be sent from a TSN node to a UE and corrected according to the delay it experiences when relayed between the 5G core network and the UE. Subsequent UE distribution of the external TSN clock from the UE to IIoT end devices is needed to enable TSN functionalities, e.g. Time- Aware Scheduling of IIoT device operations specific to the working domain (a specific factory area) associated with a given working clock.

[0030] A system 100 is depicted in FIG. 1. According to embodiments, system 100 comprises a node 102 (e.g., gNB) in communication with a UE 104. The UE 104 may service, for instance, one or more (n) devices 106, 108, which may form a time aware network. According to embodiments, the devices 106, 108 can be IIoT devices, for instance, in a factory setting. The devices 106, 108 may be part of a larger TSN that is serviced by a 5G network, including UE 104, node 102, and a network 112. The network 112 may include, for instance, a User Plane Function (UPF) node that receives information from TSN 110. For instance, messages from TSN 110 may be received and time stamped on ingress, passed to UE 104, and time stamped on egress. In some embodiments, TSN timing information is provided by TSN 110 in the form of a TSN master clock. According to embodiments, the 5G network can receive the TSN timing information via direct connectivity with TSN master clocks, e.g. via underlying transport network by having an embedded TSN client within the node 104.

[0031] As used in this disclosure, anywhere that a node such as a gNB is used, any other type of node, such as a base station (including a gNB or eNB), a transmission reception point (TRP) node, or any other network node whether utilizing 5 G technology, LTE technology, or any other communication system may be used and is within the scope of this disclosure. Likewise, as used in this disclosure, anywhere that a user equipment is used, any other type of device, such as mobile communication device, a computer, and so on, may be used and is within the scope of this disclosure.

[0032] Referring now to FIG. 2A, an example is provided where a UE 104 is sent a Ta_m command indicating TAA,P_I= m A T 2^m, as an initial TA command. In this example, the parameters might be A = 16 and m=0 for NR SCS = 15 KHz, and in one direction the propagation delay is half of TA. This may be understood, for instance, as an initial TA command with a granularity “A” and a number “m” that serves as a multiplier. T_c = .509 ns is the basic time unit in NR.

[0033] Using NR for this example, after applying the initial TA command (A times m), it is possible that messages from the UE 104 are not received by the node 102 sufficiently close to the nominal timing boundary in that the remaining timing error (i.e., departure from the nominal timing boundary) is considered to be excessive considering the timing accuracy requirements applicable for a specific TSN related use case. In other words, the more precisely the gNB receives uplink transmissions from a UE, the more precise the TA value will be. This then allows the downlink PD determined by taking one half of the TA value to be more accurate, thereby resulting in more accurate synchronization of 5G internal system clocks maintained at the UE and UPF and therefore more accurate synchronization of external TSN clocks received by the UE from the TSN node managing a given master clock. This may be the timing accuracy requirements of the TSN related to the devices 106, 108 served by UE 104. To further reduce the uplink timing error, node 104 (e.g., a gNB in this example) provides a subsequent TA command (which supplements the TA value provided by the Ta_m command). However, and according to embodiments, this new subsequent TA command has relatively finer granularity of “B” Ts, such that B < A. As illustrated in FIG. 2B, where a subsequent TA command is used to further reduce uplink timing error from what has already been realized using the initial TA command (e.g., if the gNB is still not satisfied with uplink timing error reduction resulting from the initial TA command), an additional command may be used. This may be the result of the gNB receiving the start of uplink SFN X at the left hand edge of FIG. 2B, but determining that the nominal point of its reception occurs at the boundary indicated by .5 (n+1) B T_c/ 2^m , and therefore this subsequent TA command is used, and the indicated TA is TAB.H-I = (n+1) B T 2^m.

[0034] If the gNB is still not satisfied with uplink timing error reduction provided by the first subsequent TA command, then another subsequent TA command is provided with further finer granularity of “C” Ts, where C < B < A. According to embodiments, this may be repeated as needed (e.g., until the gNB determines the uplink timing error with an acceptable range). The subsequent TA commands can follow immediately, or within a certain time period. The time period may be indicated by a timer.

[0035] According to embodiments, to realize one or more processes disclosed herein, the

UE 104 knows values for the parameters, A, B C, etc. This information may be provided to the UE in a number of ways.

[0036] For example, a gNB and UE can agree on A, B, C, etc. in an a-priori manner, and the gNB can report these values to UE through RRC, Downlink Control Information (DCI) signaling, over data channels, e.g., Physical Data Shared Channel (PDSCH), etc. In some embodiments, within a group of TA commands, the first TA command has A T_c/ 2^m granularity, the following TA command has B T_c/ 2^m granularity, and so on. [0037] In another example, and referring now to format 200 shown FIG. 2C, a new field

202 in the TA command may be used. According to embodiments, the new field 202 can denote the granularity value, and other bits 204 for the TA value (which identifies the factor by which the granularity value is to be multiplied to determine the additional TA adjustment to be made) can be provided. A gNB may send a TA command with new code space for indicating “B” and “n+1” Other information already included within legacy TA (LTE TA) can be included as well.

[0038] According to some embodiments, a single TA command is expanded to include all parts, including A, B, C, etc. An example command may have two parts, for instance. The first part uses the same granularity as existing Release- 15 granularity (i.e., A = 16); however, the second part uses finer granularity “B.” In this example:

• If the 2^nd part uses half of the existing granularity, i.e., B=A/2, then the 2^nd part needs 2 bits. T_B = 0,1,2. T_{B max} = 2.

• If the 2^nd part uses 1/4 of existing granularity, i.e., B=A/4, then the 2^nd part needs 3 bits. T_B = 0,1, 2, 3, 4. T_{B max} = 4.

• In general, if 2^nd part uses 1/N of existing granularity, i.e., B=A/N, then the 2^nd needs at least ceil(log2N) bits. T_B = 0, T_{B max} = N. o T_B can have more than N code spaces (keeping still granularity A/N). This will make T_B more robust, but resource expense will increase if the required bits is more than ceil(log2N).

• The value of A, B can be dynamically indicated if granularity field included in TA command.

Accordingly, an accurate TA can be communicated within constraints on the number of available bits.

[0039] In the above examples for realizing a target uplink timing accuracy (i.e. having an acceptable error), if enhanced TA commands are sent (e.g. a legacy TA command and one subsequent TA command with tighter granularity), then an example of the overall TA value may be as follows:

• If random access response, the enhanced timing advance command is sent to the UE for a timing advance group (TAG), where the enhanced timing advance command is composed of two parts: T_A and T_B. T_A refers to Rel-15 TA command part, T_A = 0, 1,2, ...,3846. T_B refers to the proposed new TA command part which has tighter granularity. Putting these two parts together,

• Otherwise, the enhanced timing advance command for a timing advance group (TAG) is sent to the UE to indicate adjustment of a current N_TA value, where the enhanced timing advance command is composed of two parts: T_A1 and T_A2. T_A1 refers to Rel-15 TA command part, T_A = 0, 1,2, ...,63. T_B refers to the proposed new TA command part which has tighter granularity. N_{TA new} = N_{TA old} + (T_A - 31) 16 64/2“ + (t_B - Ί y^ B 64/2^u.

According to certain aspects, basic timing unit Ts and T_c/ 2^m can be used interchangeably to represent TA implementation in LTE and NR with given SCS for parameter m respectively. The proposed methodology holds for either or any other system (LTE, NR, and other communication networks) which uses signaling similar to TA.

[0040] TA based methods (including enhancements to TA, such as those proposed here or otherwise) can be triggered by a base station (such as a gNB); alternatively, or in addition, a UE can also request a base station (such as a gNB) to provide new TA commands.

[0041] Referring now to FIG. 3, a method 300 is provided according to some embodiments. Method 300 may be performed by a node (e.g., a gNB) and may begin with step 310.

[0042] Step 310 comprises sending one or more timing advance (TA) commands to a user equipment (UE).

[0043] Step 320 comprises wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and wherein the second granularity is smaller than the first granularity.

[0044] In some embodiments, sending the one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier.

[0045] In some embodiments, the method further includes, prior to sending the second TA command with the second granularity to the UE, determining to send finer granularity timing information based on a timing error reduction between the node and the UE. Reducing timing error is alternatively stated as improving the time alignment between the node and the UE. In some embodiments, the timing error reduction between the gNB and the UE is experienced by the node on the uplink. In some embodiments, the method further includes determining to send a third TA command with a third granularity to the UE in order to further improve the timing error reduction between the node and the UE; and as a result of determining to send the third TA command with the third granularity to the UE, sending the third TA command with the third granularity to the UE, wherein the third granularity is smaller than the second granularity.

[0046] In some embodiments, the second granularity is half the first granularity. The second granularity, in other embodiments, can be any other fraction of the first granularity. In some embodiments, the method further includes signaling to the UE granularity values (e.g., the first granularity, second granularity, third granularity) to be used by the UE for successive TA commands. In some embodiments, one or more of the first, second, and third TA commands indicate the respective granularity value (e.g., the first granularity, second granularity, third granularity). In some embodiments, the first TA command with the first granularity indicates a first timing advance value TA1 = ih*A*T /2^m, where m represents a multiplier value and A represents the first granularity. In some embodiments, the method further includes determining a specific accuracy/maximum certainty target (e.g., 4*T_S) to be realized by the UE.

[0047] Some embodiments of method 300 are related to having a UE receive a 5G internal system clock, applying a set of TAs, taking one half of the resulting cumulative TA to determine the downlink PD, and then adjusting the value of the received 5G internal system clock by adding half the resulting cumulative TA to it.

[0048] In some embodiments, sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier.

[0049] In some embodiments, the method may further include determining a specific uncertainty target (e.g., 4*T_S) to be realized by the UE.

[0050] In some embodiments, the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

[0051] As indicated above, in embodiments the UE may receive a single TA command that includes multiple granularities, or it may receive multiple TA commands that each include a granularity different from the other TA commands, in order to reduce timing error and improve the timing alignment between UE and gNB. In embodiments, a UE may use information derived from one or more TA commands to update its uplink transmission timing. If the UE uplink transmission timing is not sufficiently accurate, the gNB may determine to send additional TA commands having a higher precision, so that the UE may further refine its uplink transmission timing. The information derived from the TA commands also allows the UE to correct an internal system clock received from a gNB to reflect the downlink PD, improving synchronization of clock values between the gNB and the UE.

[0052] Referring now to FIG. 4, a method 400 is provided according to some embodiments. Method 400 may be performed by a UE, and may start with step 410.

[0053] Step 410 comprises receiving one or more timing advance (TA) commands, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity.

[0054] Step 420 comprises determining a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing.

[0055] Step 430 comprises updating the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

[0056] In some embodiments, sending the one or more TA commands comprises sending a first TA command and a second TA command, and the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier. The method may further include determining a second timing advance value based on the second multiplier and the second granularity, wherein the second timing advance value represents an offset from the second uplink transmission timing. The method may further include updating the second uplink transmission timing based on the second timing advance value to generate a third uplink transmission timing.

[0057] In some embodiments, the first timing advance value is determined as TAA = hi*A*T /2^m, wherein m represents the multiplier corresponding to the first TA command and A represents the first granularity. In some embodiments, the second timing advance value is determined as TAB = h*B*T /2^m, wherein n represents the multiplier corresponding to the second TA command and B represents the second granularity. In some embodiments, the method further includes receiving a third TA command with a third granularity to the UE, wherein the third granularity is smaller than the second granularity; determining a third timing advance value TAc = o*0*T /2^m, wherein o represents a multiplier corresponding to the third TA command and C represents the third granularity, wherein the third timing advance value represents an offset from the third uplink transmission timing; and updating the third uplink transmission timing based on the third timing advance value to generate a fourth uplink transmission timing. In some embodiments, any of the offset values can be positive or negative.

[0058] In some embodiments, the second granularity is half the first granularity. In some embodiments, the method further includes receiving a signal indicating granularity values (e.g., the first granularity, second granularity, third granularity) to be used for successive TA commands. In some embodiments, one or more of the first, second, and third TA commands indicate the respective granularity value (e.g., the first granularity, second granularity, third granularity).

[0059] In some embodiments, sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier. Determining the first timing advance value is further based on the second granularity and second multiplier.

[0060] In some embodiments, the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

[0061] FIG. 5 is a block diagram of a node, such as node 102 (e.g. a gNB) or UE 104, according to some embodiments. As shown in FIG. 5, the node may comprise: a data processing apparatus (DPA) 502, which may include one or more processors (P) 555 (e.g., a general purpose microprocessor and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); a transmitter 505 and a receiver 504 coupled to an antenna 522 for enabling the node to transmit data to and receive data from an AN node (e.g., base station); and local storage unit (a.k.a., “data storage system”) 508, which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). In embodiments where the node includes a general purpose microprocessor, a computer program product (CPP) 541 may be provided. CPP 541 includes a computer readable medium (CRM) 542 storing a computer program (CP) 543 comprising computer readable instructions (CRI) 544. CRM 542 may be a non-transitory computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory), and the like. In some embodiments, the CRI 544 of computer program 543 is configured such that when executed by data processing apparatus 502, the CRI causes the node to perform steps described above (e.g., steps described above with reference to the flow charts). In other embodiments, the node may be configured to perform steps described herein without the need for code. That is, for example, data processing apparatus 502 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software.

[0062] FIG. 6A is a diagram showing functional modules of a first node, such as node 102

(e.g., a gNB), according to some embodiments. As shown in FIG. 6A, the first node comprises one or more of a sending unit 602 and a receiving unit 604. According to embodiments, sending unit 602 is arranged to send messages, such as TA commands and as described with respect to steps 310-320 of FIG. 3. According to embodiments, receiving unit 604 is arranged to receive messages, such as requests from a UE including requests for TA commands. Similarly, the first node may be adapted to send and/or receive the messages set forth in and described with respect to FIGs. 2A-2C (e.g., one or more TA commands, such as including a granularity and multiplier) and FIGs. 3-4.

[0063] FIG. 6B is a diagram showing functional modules of a second node, such as node

104 (e.g., a UE), according to some embodiments. As shown in FIG. 6B, the second node comprises one or more of a receiving unit 606, a determining unit 608, and an updating unit 610. According to embodiments, these units are arranged to perform the functions described with respect to steps 410-430 of FIGs. 46. Similarly, the second node may be adapted to send and/or receive the messages set forth in and described with respect to FIGs. 2A-2C (e.g., one or more TA commands, such as including a granularity and multiplier) and FIGs. 3-4.

[0064] While various embodiments of the present disclosure are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0065] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel. Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A method performed by a node, the method comprising: sending one or more timing advance (TA) commands to a user equipment (UE), wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and wherein the second granularity is smaller than the first granularity.

2. The method of claim 1, wherein sending one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier.

3. The method of claim 2, further comprising, prior to sending the second TA command with the second granularity to the UE, determining to send finer granularity timing information based on a timing error reduction between the node and the UE.

4. The method of claim 3, wherein the timing error reduction between the gNB and the UE is experienced by the node on the uplink.

5. The method of any one of claims 3-4, further comprising: determining to send a third TA command with a third granularity to the UE in order to further reduce the timing error between the node and the UE; and as a result of determining to send the third TA command with the third granularity to the UE, sending the third TA command with the third granularity to the UE, wherein the third granularity is smaller than the second granularity.

6. The method of any one of claims 2-5, wherein the second granularity is half the first granularity.

7. The method of any one of claims 2-6, further comprising signaling to the UE granularity values to be used by the UE for successive TA commands.

8. The method of any one of claims 5-6, wherein one or more of the first, second, and third TA commands indicate the respective granularity value.

9. The method of any one of claims 2-8, wherein the first TA command with the first granularity indicates a first timing advance value TA1 = ih*A*T /2^m, where m represents the first multiplier and A*T /2^m represents the first granularity.

10. The method of any one of claims 2-9, further comprising determining a specific uncertainty target to be realized by the UE as a result of sending to the UE the one or more TA commands.

11. The method of claim 1, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier.

12. The method of claim 11, wherein the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

13. The method of any one of claims 11-12, further comprising determining a specific uncertainty target to be realized by the UE as a result of sending to the UE the one or more TA commands.

14. A method performed by a user equipment (UE), the method comprising: receiving one or more timing advance (TA) commands, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity; determining a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing; and updating the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

15. The method of claim 14, wherein sending the one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier, the method further comprising: determining a second timing advance value based on the second multiplier and the second granularity, wherein the second timing advance value represents an offset from the second uplink transmission timing; and updating the second uplink transmission timing based on the second timing advance value to generate a third uplink transmission timing.

16. The method of claim 15, wherein the first timing advance value is determined as TAA = ih*A*T /2^m, wherein m represents the multiplier corresponding to the first TA command and A*T /2^m represents the first granularity.

17. The method of any one of claims 15-16, wherein the second timing advance value is determined as TAB = h*B*T /2^m, wherein n represents the multiplier corresponding to the second TA command and B*T /2^m represents the second granularity.

18. The method of any one of claims 15-17, further comprising: receiving a third TA command with a third granularity to the UE, wherein the third granularity is smaller than the second granularity; determining a third timing advance value TAc = o*(2*T /2^m, wherein o represents a multiplier corresponding to the third TA command and (2*T /2^m represents the third granularity, wherein the third timing advance value represents an offset from the third uplink transmission timing; and updating the third uplink transmission timing based on the third timing advance value to generate a fourth uplink transmission timing.

19. The method of any one of claims 15-18, wherein any of the offset values can be positive or negative.

20. The method of any one of claims 15-19, wherein the second granularity is half the first granularity.

21. The method of any one of claims 15-20, further comprising receiving a signal indicating granularity values to be used for successive TA commands.

22. The method of any one of claims 18-20, wherein one or more of the first, second, and third TA commands indicate the respective granularity value.

23. The method of claim 14, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier, and wherein determining the first timing advance value is further based on the second granularity and second multiplier.

24. The method of claim 23, wherein the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

25. A computer program comprising instructions which when executed by processing circuitry causes the processing circuitry to perform the method of any one of claims 1-24.

26. A carrier containing the computer program of claim 25, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

27. A node, the node being adapted to: send one or more timing advance (TA) commands to a user equipment (UE), wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and wherein the second granularity is smaller than the first granularity.

28. The node of claim 27, wherein sending the one or more TA commands comprises sending a first TA command and a second TA command, and wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier.

29. The node of claim 28, wherein the node is further adapted to, prior to sending the second TA command with the second granularity to the UE, determine to send finer granularity timing information based on a timing error reduction between the node and the UE.

30. The node of claim 29, wherein the timing error reduction between the gNB and the UE is experienced by the node on the uplink.

31. The node of any one of claims 29-30, wherein the node is further adapted to: determine to send a third TA command with a third granularity to the UE in order to further improve the timing error reduction between the node and the UE; and as a result of determining to send the third TA command with the third granularity to the UE, send the third TA command with the third granularity to the UE, wherein the third granularity is smaller than the second granularity.

32. The node of any one of claims 28-31, wherein the second granularity is half the first granularity.

33. The node of any one of claims 28-32, wherein the node is further adapted to signal to the UE granularity values to be used by the UE for successive TA commands.

34. The node of any one of claims 31-32, wherein one or more of the first, second, and third TA commands indicate the respective granularity value.

35. The node of any one of claims 28-34, wherein the first TA command with the first granularity indicates a first timing advance value TA1 = ih*A*T /2^m, where m represents a multiplier value and A represents the first granularity.

36. The node of any one of claims 28-35, wherein the node is further adapted to determine a specific uncertainty target to be realized by the UE.

37. The node of claim 27, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier.

38. The node of claim 37, wherein the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

39. The node of any one of claims 37-38, the node being further adapted to determine a specific uncertainty target to be realized by the UE.

40. A user equipment (UE), the UE being adapted to: receive one or more timing advance (TA) command, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity; determine a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing; and update the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

41. The UE of claim 40, wherein sending the one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier, the UE further being adapted to: determine a second timing advance value based on the second multiplier and the second granularity, wherein the second timing advance value represents an offset from the second uplink transmission timing; and update the second uplink transmission timing based on the second timing advance value to generate a third uplink transmission timing.

42. The UE of claim 41, wherein the first timing advance value is determined as TAA = hi*A*T /2^m, wherein m represents the multiplier corresponding to the first TA command and A represents the first granularity.

43. The UE of claims 41-42, wherein the second timing advance value is determined as TAB = h*B*T /2^m, wherein n represents the multiplier corresponding to the second TA command and B represents the second granularity.

44. The UE of any one of claims 41-43, the UE being further adapted to: receive a third TA command with a third granularity to the UE, wherein the third granularity is smaller than the second granularity; determine a third timing advance value TAc = o*(3*T /2^m, wherein o represents a multiplier corresponding to the third TA command and C represents the third granularity, wherein the third timing advance value represents an offset from the third uplink transmission timing; and update the third uplink transmission timing based on the third timing advance value to generate a fourth uplink transmission timing.

45. The UE of any one of claims 41-44, wherein any of the offset values can be positive or negative.

46. The UE of any one of claims 41-45, wherein the second granularity is half the first granularity.

47. The UE of any one of claims 41-46, wherein the UE is further adapted to receive a signal indicating granularity values to be used for successive TA commands.

48. The UE of any one of claims 44-46, wherein one or more of the first, second, and third TA commands indicate the respective granularity value.

49. The UE of claim 40, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier, and wherein determining the first timing advance value is further based on the second granularity and second multiplier.

50. The user equipment of claim 49, wherein the first TA command further includes a third granularity and a third multiplier corresponding to the third granularity.

51. A node (e.g., a gNB), the node comprising: a sending unit configured to send one or more timing advance (TA) commands to a user equipment (UE), wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, and wherein the second granularity is smaller than the first granularity.

52. The node of claim 51, wherein sending the one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier.

53. The node of claim 51, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier.

54. A user equipment (UE), the UE comprising: a receiving unit configured to receive one or more timing advance (TA) command, wherein the one or more TA commands include a first granularity and a first multiplier corresponding to the first granularity and a second granularity and a second multiplier corresponding to the second granularity, wherein the second granularity is smaller than the first granularity; a determining unit configured to determine a first timing advance value based at least on the first multiplier and the first granularity, wherein the first timing advance value represents an offset from a first uplink transmission timing; and an updating unit configured to update the first uplink transmission timing based on the first timing advance value to generate a second uplink transmission timing.

55. The UE of claim 54, wherein sending the one or more TA commands comprises sending a first TA command and a second TA command, wherein the first TA command includes the first granularity and the first multiplier, and the second TA command includes the second granularity and the second multiplier, and wherein the determining unit is further configured to determine a second timing advance value based on the second multiplier and the second granularity, wherein the second timing advance value represents an offset from the second uplink transmission timing; and the updating unit is further configured to update the second uplink transmission timing based on the second timing advance value to generate a third uplink transmission timing.

56. The UE of claim 54, wherein sending the one or more TA commands comprises sending a first TA command, and the first TA command includes the first granularity, the first multiplier, the second granularity, and the second multiplier, and wherein determining the first timing advance value is further based on the second granularity and second multiplier.