WO2022078920A1

WO2022078920A1 - Methods and systems for propagation delay compensation

Info

Publication number: WO2022078920A1
Application number: PCT/EP2021/077966
Authority: WO
Inventors: Zhenhua Zou; Yufei Blankenship
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2020-10-16
Filing date: 2021-10-08
Publication date: 2022-04-21

Abstract

A method performed by a network node is provided. The method comprises transmitting toward a user equipment (UE) an order. The method further comprises after transmitting the order, obtaining timing information indicating the UE's uplink signal transmission timing. The method further comprises after obtaining the timing information, transmitting toward the UE a message containing a timing advance (TA) command. The TA command is configured to trigger the UE to adjust the UE's uplink signal transmission timing.

Description

METHODS AND SYSTEMS FOR PROPAGATION DELAY COMPENSATION

TECHNICAL FIELD

[0001] Disclosed are embodiments related to methods and systems for propagation delay compensation.

BACKGROUND

[0002] There are different options for propagation delay compensation. The options are the followings:

[0003] The legacy multi-RTT positioning method makes use of the UE Rx-Tx time difference measurements and Downlink (DL) Positioning Reference Signal (PRS) Reference Signal Received Power (RSRP) of downlink signals received from multiple TRPs measured by the UE, and the measured gNB Rx-Tx time difference measurements and UL-SRS-RSRP at multiple TRPs of uplink signals transmitted from UE. The measurements are used to determine the RTT at the positioning server which are used to estimate the location of the UE. [0004] The RTT based delay compensation is leveraged on the legacy multi-RTT positioning method illustrated in FIG. 1. As shown in FIG. 1, the user equipment (UE) 102 (which can be any device capable of wirelessly communicating with a base station) transmits an uplink frame i and records the transmission time as ti. The base station (gNB) 104 receives uplink frame i and records the time of arrival of the first detected path as t3. Next, the gNB transmits a downlink frame j to the UE, and records transmission time as t2. Next, the UE receives downlink frame j and records the time of arrival of the first detected path as U. The following calculations are performed in the UE and gNB, respectively: i) UE R_X-TX diff= ti- ti; and ii) gNB R_X-Txdiff= t3- 12. This quantity can be positive or negative depending on the whether gNB transmits the DL frame before or after receiving the UL frame. The propagation delay can be calculated as follows: RTT= (gNB Rx - Tx time difference) + (UE Rx - Tx time difference).

[0005] The reference cell for reference time delivery is the Primary Cell (PCell). The reference time information sent on Radio Resource Control (RRC) contains a field that indicates the reference System Frame Number (SFN) corresponding to the reference time information. It is possible to have unaligned SFN across carriers in a cell group, and thus a reference cell is needed and defined in RRC that “If referenceTimelnfo field is received in DLInformationTransfer message, this field indicates the SFN of PCell.” PSCell is not included as DLInformationTransfer is sent on SRB1/2 on MCG not on SCG Additionally, SIB9 is only broadcasted on PCell and this restriction aligns the RRC-dedicated and broadcast message for reference time delivery.

SUMMARY

[0006] Certain challenges presently exist. For instance, although the principle of the propagation delay compensation method is the same as the Timing Advance (TA) for uplink timing alignment and Round-Trip-Time (RTT) for positioning, the signalling details to support those two approaches (i.e., TA and RTT) on the Access Stratum (AS) layer are missing.

[0007] Accordingly, in one aspect, there is provided a method performed by a network node. The method comprises transmitting toward a user equipment (UE) an order. The method further comprises after transmitting the order, obtaining (s404) timing information indicating the UE’s uplink signal transmission timing. The method further comprises after obtaining the timing information, transmitting toward the UE a message containing a timing advance (TA) command. The TA command is configured to trigger the UE to adjust the UE’s uplink signal transmission timing.

[0008] In another aspect, there is provided a method performed by a user equipment (UE). The method comprises receiving from a network node an order and after receiving the order, transmitting toward the network node timing information indicating UE’s uplink signal transmission timing. The method further comprises after transmitting the timing information, receiving from the network node a message containing a timing advance (TA) command, and adjusting the UE’s uplink signal transmission timing based on the TA command.

[0009] In another aspect, there is provided a computer program comprising instructions which when executed by processing circuitry cause the processing circuitry to perform the methods described above.

[0010] In another aspect, there is provided an apparatus. The apparatus is configured to transmit toward a user equipment (UE) an order, and after transmitting the order, obtain timing information indicating the UE’s uplink signal transmission timing. The apparatus is further configured to after obtaining the timing information, transmit toward the UE a message containing a timing advance (TA) command. The TA command is configured to trigger the UE to adjust the UE’s uplink signal transmission timing.

[0011] In another aspect, there is provided an apparatus configured to receive from a network node an order, and after receiving the order, transmit toward the network node timing information indicating UE’s uplink signal transmission timing. The apparatus is further configured to after transmitting the timing information, receive from the network node a message containing a timing advance (TA) command, and adjust the UE’s uplink signal transmission timing based on the TA command.

[0012] In another aspect, there is provided an apparatus. The apparatus comprises a memory and processing circuitry coupled to the memory. The apparatus is configured to perform the methods described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments. [0014] FIG. 1 is a message flow diagram illustrating a process for determining RTT.

[0015] FIG. 2 is an example of a simplified message flow diagram according to some embodiments.

[0016] FIGS. 3 A-3D show examples of MAC CE.

[0017] FIG. 4 is a flowchart illustrating a process according to some embodiments.

[0018] FIG. 5 is a flowchart illustrating a process according to some embodiments.

[0019] FIG. 6 illustrates a gNB according to some embodiments.

[0020] FIG. 7 illustrates a UE according to some embodiments.

DETAILED DESCRIPTION

[0021] 1. Timing Advance (TA) Command

[0022] To compensate for the propagation delay, TA is used in the embodiments of this disclosure. TA enables a user equipment (UE) to adjust its uplink (UL) signal transmission timing to better align the timing of receiving data from the UE at a base station (BS) with the timing of sending data from the BS to the UE. If data (e.g., Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), etc.) transmitted from the UE is arrived at the BS too early, the BS may send to the UE a TA command asking the UE to transmit data a little bit late. On the other hand, if data transmitted from the UE is arrived at the BS too late, the BS may send to the UE a TA command asking the UE to transmit data a little bit early.

[0023] Depending on the degree of adjusting the UL signal transmission timing, a TA command may be categorized as a finer granularity TA command and a legacy TA command. In some embodiments of this disclosure, the finer granularity TA command and/or the legacy TA command may be used for TA.

[0024] TA command may be sent either as an incremental TA command or as an absolute TA command. TA command may be sent using the following two signaling approaches: (1) Using the Random Access Response (e.g., Medium Access Control (MAC) Random Access Response (RAR) or fallbtack RAR)) for the transmission of an absolute TA command and (2) Using a separate MAC Control Element (CE) for either an incremental TA command or an absolute TA command. [0025] 2. Absolute TA Command

[0026] Absolute TA command (the TA command that does not depend on any previously used/ stored time adjustment) may only be transmitted during random access procedure.

[0027] FIG. 2 shows an example of a simplified message flow diagram 200 according to some embodiments. The diagram 200 shows messages exchanged between UE 102 and BS 104.

[0028] As shown in FIG. 2, BS 104 (e.g., eNB, gNB, etc.) may transmit to UE 102 a Physical Downlink Control Channel (PDCCH) order 202. PDCCH order 202 is a mechanism by which BS 104 forces UE 102 to initiate Physical Random Access Channel (PRACH). Via PRACH, BS 104 may obtain an up-to-date UL timing information 204 from UE 102. After UE’s UL transmission of the up-to-date UL timing information 204, the Absolute Timing Advance Command MAC CE 206 (e.g., as defined in 6.1.3.4a of TS 38.321) may be used as a response to indicate the absolute TA command.

[0029] Generally, MAC CE applies for Primary Timing Advance Group (PT AG) but it may only be sent by BS 104 in response to a MsgA transmission from UE 102 including a Cell Radio Network Temporary Identifier (C-RNTI) MAC CE. Also, in Rel-16 UE expects and applies the absolute TA command MAC CE if the timeAlignmentTimer associated with the PT AG is not running. timeAlignmentTimer is a configurable timer provided by BS 104 to UE 102. timeAlignmentTimer may be used to control how long UE 102 may consider or assume that UL timing is aligned.

[0030] In some embodiments of this disclosure, BS 104 may send a PDCCH order 202 even if UE 102 and BS 104 are not out of sync (i.e., the associated timeAlignmentTimer is still running). In such case, UE 102 may apply the absolute TA command MAC CE regardless of the status of the associated timeAlignmentTimer for the PTAG.

[0031] The Rel-16 absolute TA command MAC CE may have the form shown in FIG. 3A (e.g., as shown in subclause 6.1.3.4a of TS 38.321 vl6.2.1). The TA command field may indicate the index value TA that is used to control the amount of timing adjustment that the MAC entity has to apply. In one example, the size of the TA command field is 12 bits. [0032] For a Subcarrier Spacing (SCS) of 2^ ■ 15 kHz, the legacy TA command for a Timing Advance Group (TAG) may indicate the amount of change of the UL timing relative to

the current UL timing for the TAG in multiples of 16 ■ 64 ■ With the indicated T_A in the

absolute TA command Medium Access Control (MAC) Control Element (CE), the amount of the time alignment (i.e., adjustment) for the TAG with SCS of 2^ ■ 15 kHz is N_TA= T_A - 16 - ^⁶ .

[0033] For a fine granularity TA command, m extra bits may be used to signal a TA command with finer granularity In such case, the granularity may be that of the existing

TA command (regardless of whether the TA command is absolute or incremental). Therefore, if the value of the finer granularity TA command in the message from the gNB is (TA)’, then the acutal TA for the UE is

[0034] In some embodiments, the first four or part of these four reserved bits in the Rel-16 absolute TA command MAC CE may be used to indicate a finer granularity beyond the smallest granularity that may be expressed by the index value. An example of using three bits (e.g., m=3) to indicate a finer granularity is shown in FIG. 3B.

[0035] In this example, if the finer TA command has three bits, then it may indicate a granularity of one eighth of the TA granularity in Rel-15 and Rel-16, i.e.,

8

[0036] In some embodiments, the legacy MAC CE is not reused by repurposing the “reserved bits” but a new MAC CE with a new (e)LCID is defined. In this new MAC CE, the granularity may be enhanced and the finer granularity TA commend (the one beyond the Rel- 15/16 TA command) may be indicated by the finer TA command field as shown in FIG. 3C.

[0037] In other embodiments, the finer TA commands (like the one shown in FIG. 3C) may be added in the Random- Access Response (e.g., the MAC RAR or the fallbackRAR).

[0038] 3. Incremental TA Command [0039] Incremental TA command may be used when UE 102 is previously uplink synchronized to BS 104 (e.g., gNB) and only occasional adjustments might be needed.

[0040] In one embodiment, for incremental TA command, a new finer TA command MAC CE with a new (e)LCID may be defined. FIG. 3D shows an example of MAC CE only with a finer TA command.

[0041] The finer TA command MAC CE may not have TAG ID field and it may apply only for PTAG. Additionally, UE 102 may not be expected to receive this MAC CE from the Secondary Cell Group (SCG). The reason for this restriction is that the reference time refers to the System Frame Number (SFN) of the PCell and only the PTAG of the Master Cell Group (MCG) contains the PCell. In general, if m extra bits are provided to signal a TA command with finer granularity, then the granularity is of the existing TA command (which may

indicate either absolute timing or incremental timing).

[0042] 4. UE’s Actions in Response to Receiving the TA Commands

[0043] Once UE 102 receives a TA command, UE 102 may use the TA command for propagation delay compensation. From the received TA command, UE 102 may determine the time difference between a DL frame and a UL frame. The half of the time difference is the propagation delay.

[0044] In one embodiment, when UE 102 receives an update of the reference time from the gNB on either SIB9 or the RRC-dedicated message (i.e., DLInformationTransfer), UE 102 may only utilize the TA commands (also finer TA commands if included) from the PTAG of the MCG when its associated timeAlignmentTimer has not expired. This is due to that the reference time refers to the SFN of the PCell and only the PTAG of the MCG contains the PCell.

[0045] In another embodiment, UE 102 may not be required to apply the finer TA command for UL transmission timing but may be configured to only compensate the propagation delay for the reference time. In some embodiments, if UE 102 is configured by the network through RRC message to apply propagation delay compensation (e.g., by PropagationDelayCompensation), UE 102 may deliver a finer TA command along with the (Rel-15/16) TA command to the upper layer for delay compensation or UE 102 may apply the delay compensation in RRC and deliver the reference time to the upper layer.

[0046] In some embodiments, UE may apply propagation delay compensation (i.e., delivers a finer TA command along with the (Rel-15/16) TA command to the upper layer for delay compensation or applies the delay compensation in RRC and delivers the reference time to the upper layer), if any MAC CE or RAR with a finer TA command is received. This is an implicit method to turn-on propagation delay compensation at UE 102.

[0047] In another embodiment, at the reception of a command with only finer TA command MAC CE (as shown in FIG. 3D), UE 102 does not (re) -start the time alignment timer for PTAG, while for other MAC CEs or RAR in which finer TA commands exist in addition to the legacy TA command, at the reception of the commands, UE 102 may (re)-start the time alignment timer for PTAG.

[0048] 5. Types of Downlink (DL) and Uplink (UL) Reference Signals (RS)

Supporting Finer Granularity TA commands

[0049] To provide TA commands with finer granularity (for absolute TA commands and/or incremental TA commands), better DL and/or UL reference signals are needed. Accordingly, in some embodiments, in order for NN 104 (e.g., gNB) to estimate uplink timing properly and send meaningful finer TA command values, a set of RS may be defined specifically for the purpose of uplink transmission timing estimation.

[0050] For example, the RS may be Sounding Reference Signals (SRS) and there may be a requirement on the minimum number of physical resource blocks (PRBs).

[0051] In another example, for DL RS, any one or more of tracking reference signals (TRS), enhanced TRS, positioning reference signals (PRS), or enhanced PRS may be used to improve UE 102’s detection of downlink signal timing. For UL RS, either SRS for positioning or SRS for time synchronization may be used to improve NN 104’s detection of UL signal timing.

[0052] 6. Configuration Example of Reference Signals — SRS

[0053] In some embodiments, in the Radio Resource Control (RRC) message that configures UE 102 to compensate propagation delay compensation, a pointer to the reference signalling resource may be added. This reference signalling may be configured by the RRC parameter — SRS-Config — of the Primary Serving Cell (PCell). The pointer may contain the srs-ResourceSetld and BWP ID, but not Cell ID.

[0054] The resource may be any one of aperiodic, semi-periodic, and periodic as configured in the IE SRS-Config. In some embodiments, multiple resources may be configured, where each one corresponds to one configured uplink BWP.

[0055] The resource may be used after the Bandwidth Part (BWP) switching and the concerned BWP is activated. For semi-persistent SRS resources, it can be activated or deactivated using the legacy SP SRS Activation/Deactivation MAC CE. For aperiodic SRS resources, it can be triggered by Downlink Control Information (DCI).

[0056] In one example, the RRC SRS configuration for propagation delay compensation may be different from normal SRS configuration or SRS configuration for positioning, e.g., transmitted using a different antenna port, a different power setting, a different BW, a different set of symbols, etc.

[0057] 7. Achievable Time Synchronization Accuracy

[0058] The granularity of achievable time synchronization accuracy may depend on various parameters and configurations.

[0059] In some embodiments, the granularity achievable of the enhanced TA command may be a function of the downlink SCS of the active BWP, and/or uplink SCS of the active BWP.

[0060] In some embodiments, the granularity achievable of the enhanced TA command may be a function of the configuration parameters of the DL reference signal (e.g., DL PRS and/or DL TRS). The configuration parameters may include bandwidth of the DL RS, frequency domain density of DL RS, time domain density of DL RS, time domain duration of DL RS burst, periodicity of DL RS, etc.

[0061] In some embodiments, the granularity achievable of the enhanced TA command may be a function of the configuration parameters of the UL reference signal (e.g., UL SRS). The configuration parameters may include bandwidth of the UL RS, frequency domain density of UL RS, time domain density of UL RS, periodicity of UL RS, etc. [0062] In some embodiments, several levels (e.g., k’) of achievable granularity may defined. For example, k’={0,l,2,3,4,5} wherein k’=0 corresponds to the finest granularity and k’=5 corresponds to coarsest granularity. The granularity level may be negotiated between UE and gNB.

[0063] For example, the gNB may signal the desired granularity level k’ to UE. The UE can reply with the actually realized k’ to the gNB, which may or may not be equal to the desired k’ from gNB.

[0064] In another example, the UE may signal the desired granularity level k’ to gNB. The gNB can reply with the actually realized k’ to the UE, which may or may not be equal to the desired k’ from UE. This k’ value depends on the synchronization accuracy requirement at the application layer (e.g., part of the information in the time sensitive networking (TSN) configuration). In this approach, UE may request more than one k values and gNB can reply to the UE that none of them can be supported.

[0065] In one example, the number of bits for finer granularity TA command is consequently (m-k’). The actual TA for UE, in this case, may e expressed as

[0067] T_{A K} is the signaled value (integer) in the message that is contained in the TA command. It is different for different k since the number of bits is different.

[0068] In another approach, no negotiation is allowed. For instance, gNB selects one k value based on UE capability, the SCS of the current activated BWPs, and the available remaining reference signal resources in the cell and etc. In other words, this is a configuration from the gNB.

[0069] 8. Improved UE Transmission Timing Error (Te)

[0070] In some embodiments, to support enhanced TA, the UE transmission timing error (Te) may be reduced. For example, in some embodiments, only the longer Te values are reduced (e.g., halved) while the shorter Te values are left unchanged, as shown in Table 1 (corresponding to Table 7.1.2-1 of Technical Specification 38.133) provided below. Reducing only the longer Te allows reducing the TA error where it is most problematic for achieving the tight time synchronization accuracy.

[0071] Table 1: T_e Timing Error Limit and its enhancement

[0072] To help achieving the reduced Te, the conditions on Te may be revised to help UE to achieve the tighter requirement.

[0073] For example, the reduced Te may be applicable only for certain uplink transmissions while existing Te applies for other uplink transmissions. More specifically, the reduced Te may be applicable only to the transmission of SRS and/or PRACH transmission, and not applicable to PUCCH or PUSCH transmission.

[0074] In another example, the reduced Te requirement is applicable only to the transmission of SRS and/or PRACH transmission on PCell, or for at most one UL reference signal configurations in the PCell, etc.

[0075] In one example, when it is the first transmission in a DRX cycle, the UE is required to meet the Te requirement for an initial transmission only if better DL reference is provided. For instance, the condition for Te is that at least one SSB is available at the UE during the last T ms, where T<160 (ms). Alternatively, the condition for Te is that at least one PRS or TRS is available at the UE during the last T’ ms, where an exemplary value of T’ is T’= 20ms. [0076] The reduced Te may require more advanced UE implementation. Thus, a UE can report its capability in achieving the reduced Te. For example, a UE capability is introduced where the UE can indicate if it can, or cannot, achieve the reduced Te in the relevant condition. In another example, a UE capability is introduced where the UE can indicate the level of Te it can achieve, if multiple levels of Te are possible.

[0077] FIG. 4 is a process 400 performed by a network node 104. The process 400 may begin with step s402. Step s402 comprises transmitting toward a user equipment (UE) an order. Step s404 comprises after transmitting the order, obtaining timing information indicating UE’s uplink signal transmission timing. Step s406 comprises after obtaining the timing information, transmitting toward the UE a message containing a timing advance (TA) command. The TA command is configured to trigger the UE to adjust the UE’s uplink signal transmission timing.

[0078] In some embodiments, the order is a physical downlink control channel (PDCCH) order, and the PDCCH order is transmitted toward the UE regardless of whether the UE and the network node are out of synchronization.

[0079] In some embodiments, the method further comprises transmitting toward the UE a timer parameter containing a value of a timer. The value of a timer indicates to the UE how long uplink signal transmission timing is considered to be aligned with downlink signal transmission timing, and the PDCCH order is transmitted toward the UE regardless of whether the timer is running or not at the time of transmitting the PDCCH order.

[0080] In some embodiments, the TA command includes a first group of bits and a second group of bits, the first group of bits indicates a first index value, and the second group of bits indicates a second index value, and the first and second index values determine the amount of adjusting the UE’s uplink signal transmission timing.

[0081] In some embodiments, the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first and the second index values, and the amount of adjusting the UE’s uplink signal transmission timing is inversely proportional to m.

[0082] In some embodiments, granularity of the TA command is a function of any one or a combination of the followings: downlink SCS of an active BWP, uplink SCS of the active BWP, bandwidth of DL RS, frequency domain density of DL RS, time domain density of DL RS, time domain duration of DL RS burst, periodicity of DL RS, bandwidth of UL RS, frequency domain density of UL RS, and time domain density of UL RS, periodicity of UL RS.

[0083] FIG. 5 is a process 500 performed by a user equipment (UE) according to some embodiments. The process 500 may begin with step s502. Step s502 comprises receiving from a network node an order. Step s504 comprises after receiving the order, transmitting toward the network node timing information indicating UE’s uplink signal transmission timing. Step s506 comprises after transmitting the timing information, receiving from the network node a message containing a timing advance (TA) command. Step s508 comprises adjusting the UE’s uplink signal transmission timing based on the TA command.

[0084] In some embodiments, the order is a physical downlink control channel (PDCCH) order, and the PDCCH order is transmitted toward the UE regardless of whether the UE and the network node are out of synchronization.

[0085] In some embodiments, the method further comprises receiving from the network node a timer parameter containing a value of a timer. The value of a timer indicates to the UE how long uplink signal transmission timing is considered to be aligned with downlink signal transmission timing, and the PDCCH order is transmitted toward the UE regardless of whether the timer is running or not at the time of transmitting the PDCCH order.

[0086] In some embodiments, the TA command includes a first group of bits and a second group of bits, the first group of bits indicates a first index value, and the second group of bits indicates a second index value, and the first and second index values determine the amount of adjusting the UE’s uplink signal transmission timing.

[0087] In some embodiments, the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first and the second index values, and the amount of adjusting the UE’s uplink signal transmission timing is inversely proportional to m.

[0088] In some embodiments, the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first index value, and the amount of adjusting the UE’s uplink signal transmission timing is not affected by m and the second index value.

[0089] In some embodiments, the message containing the TA command is associated with a Primary Timing Advance Group, the method further comprises receiving a message containing another timing advance (TA) command, the message containing said another TA command is associated with a secondary TAG that is different from the pTAG, and the method further comprises not adjusting the UE’s uplink signal transmission timing based on said another TA command.

[0090] In some embodiments, granularity of the TA command is a function of any one or a combination of the followings: downlink SCS of an active BWP, uplink SCS of the active BWP, bandwidth of DL RS, frequency domain density of DL RS, time domain density of DL RS, time domain duration of DL RS burst, periodicity of DL RS, bandwidth of UL RS, frequency domain density of UL RS, and time domain density of UL RS, periodicity of UL RS.

[0091] PIG. 6 is a block diagram of base station 104, according to some embodiments, for performing base station methods disclosed herein. As shown in FIG. 6, base station 104 may comprise: processing circuitry (PC) 602, which may include one or more processors (P) 655 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., base station 104 may be a distributed computing apparatus); at least one network interface 668 comprising a transmitter (Tx) 665 and a receiver (Rx) 667 for enabling base station 104 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 668 is connected; communication circuitry 648, which is coupled to an antenna arrangement 649 comprising one or more antennas and which comprises a transmitter (Tx) 645 and a receiver (Rx) 647 for enabling base station 104 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a local storage unit (a.k.a., “data storage system”) 608, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In embodiments where PC 602 includes a programmable processor, a computer program product (CPP) 641 may be provided. CPP 641 includes a computer readable medium (CRM) 642 storing a computer program (CP) 643 comprising computer readable instructions (CRI) 644. CRM 642 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 644 of computer program 643 is configured such that when executed by PC 602, the CRI causes base station 104 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, base station 104 may be configured to perform steps described herein without the need for code. That is, for example, PC 602 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software.

[0092] FIG. 7 is a block diagram of UE 102, according to some embodiments. As shown in FIG. 7, UE 102 may comprise: processing circuitry (PC) 702, which may include one or more processors (P) 755 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); communication circuitry 748, which is coupled to an antenna arrangement 749 comprising one or more antennas and which comprises a transmitter (Tx) 745 and a receiver (Rx) 747 for enabling UE 102 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a local storage unit (a.k.a., “data storage system”) 708, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In embodiments where PC 702 includes a programmable processor, a computer program product (CPP) 741 may be provided. CPP 741 includes a computer readable medium (CRM) 742 storing a computer program (CP) 743 comprising computer readable instructions (CRI) 744. CRM 742 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 744 of computer program 743 is configured such that when executed by PC 702, the CRI causes UE 102 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, UE 102 may be configured to perform steps described herein without the need for code. That is, for example, PC 602 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software.

Claims

CLAIMS:

1. A method (400) performed by a network node (104), the method comprising: transmitting (s402) toward a user equipment, UE, an order; after transmitting the order, obtaining (s404) timing information indicating the UE’s uplink signal transmission timing; and after obtaining the timing information, transmitting (s406) toward the UE a message containing a timing advance, TA, command, wherein the TA command is configured to trigger the UE to adjust the UE’s uplink signal transmission timing.

2. The method of claim 1, wherein the order is a physical downlink control channel, PDCCH, order, and the PDCCH order is transmitted toward the UE regardless of whether the UE and the network node are out of synchronization.

3. The method of claim 2, the method further comprising transmitting toward the UE a timer parameter containing a value of a timer, wherein the value of a timer indicates to the UE how long uplink signal transmission timing is considered to be aligned with downlink signal transmission timing, and the PDCCH order is transmitted toward the UE regardless of whether the timer is running or not at the time of transmitting the PDCCH order.

4. The method of any one of claims 1-3, wherein the TA command includes a first group of bits and a second group of bits, the first group of bits indicates a first index value, and the second group of bits indicates a second index value, and the first and second index values determine the amount of adjusting the UE’s uplink signal transmission timing.

5. The method of claim 4, wherein

16

RECTIFIED SHEET (RULE 91) ISA/EP the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first and the second index values, and the amount of adjusting the UE’s uplink signal transmission timing is inversely proportional to m.

6. The method of any one of claims 1-5, wherein granularity of the TA command is a function of any one or a combination of the followings: downlink SCS of an active BWP, uplink SCS of the active BWP, bandwidth of DL RS, frequency domain density of DL RS, time domain density of DL RS, time domain duration of DL RS burst, periodicity of DL RS, bandwidth of UL RS, frequency domain density of UL RS, and time domain density of UL RS, periodicity of UL RS.

7. A method (500) performed by a user equipment, UE, (102), the method comprising: receiving (s502) from a network node an order; after receiving the order, transmitting (s504) toward the network node timing information indicating UE’s uplink signal transmission timing; after transmitting the timing information, receiving (s506) from the network node a message containing a timing advance, TA, command; and adjusting (s508) the UE’s uplink signal transmission timing based on the TA command.

8. The method of claim 7, wherein the order is a physical downlink control channel, PDCCH, order, and the PDCCH order is transmitted toward the UE regardless of whether the UE and the network node are out of synchronization.

9. The method of claim 8, the method further comprising receiving from the network node a timer parameter containing a value of a timer, wherein

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RECTIFIED SHEET (RULE 91) ISA/EP the value of a timer indicates to the UE how long uplink signal transmission timing is considered to be aligned with downlink signal transmission timing, and the PDCCH order is transmitted toward the UE regardless of whether the timer is running or not at the time of transmitting the PDCCH order.

10. The method of any one of claims 7-9, wherein the TA command includes a first group of bits and a second group of bits, the first group of bits indicates a first index value, and the second group of bits indicates a second index value, and the first and second index values determine the amount of adjusting the UE’s uplink signal transmission timing.

11. The method of claim 10, wherein the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first and the second index values, and the amount of adjusting the UE’s uplink signal transmission timing is inversely proportional to m.

12. The method of claim 10, wherein the second group of bits consists of m bits, m is a positive integer, the amount of adjusting the UE’s uplink signal transmission timing is proportional to the first index value, and the amount of adjusting the UE’s uplink signal transmission timing is not affected by m and the second index value.

13. The method of any one of claims 7-12, wherein the message containing the TA command is associated with a Primary Timing Advance Group, pTAG,

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RECTIFIED SHEET (RULE 91) ISA/EP the method further comprises receiving a message containing another timing advance, TA, command, the message containing said another TA command is associated with a secondary TAG that is different from the pTAG, and the method further comprises not adjusting the UE’s uplink signal transmission timing based on said another TA command.

14. The method of any one of claims 7-13, wherein granularity of the TA command is a function of any one or a combination of the followings: downlink SCS of an active BWP, uplink SCS of the active BWP, bandwidth of DL RS, frequency domain density of DL RS, time domain density of DL RS, time domain duration of DL RS burst, periodicity of DL RS, bandwidth of UL RS, frequency domain density of UL RS, and time domain density of UL RS, periodicity of UL RS.

15. A computer program (643 or 743) comprising instructions (644 or 744) which when executed by processing circuitry (602 or 702) cause the processing circuitry to perform the method of any one of claims 1-14.

16. A carrier containing the computer program of claim 15, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

17. An apparatus (600), the apparatus being configured to: transmit (s402) toward a user equipment, UE, an order; after transmitting the order, obtain (s404) timing information indicating the UE’s uplink signal transmission timing; and after obtaining the timing information, transmit (s406) toward the UE a message containing a timing advance, TA, command, wherein the TA command is configured to trigger the UE to adjust the UE’s uplink signal transmission timing.

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18. The apparatus of claim 20, wherein the apparatus is further configured to perform the method of any one of claims 2-6.

19. An apparatus (600), the apparatus comprising: a memory (642); and processing circuitry (602) coupled to the memory, wherein the apparatus is configured to perform the method of any one of claims 1 -6.

20. An apparatus (700), the apparatus being configured to: receive (s502) from a network node an order; after receiving the order, transmit (s504) toward the network node timing information indicating UE’s uplink signal transmission timing; after transmitting the timing information, receive (s506) from the network node a message containing a timing advance, TA, command; and adjust (s508) the UE’s uplink signal transmission timing based on the TA command.

21. The apparatus of claim 22, wherein the apparatus is further configured to perform the method of any one of claims 8-14.

22. An apparatus (700), the apparatus comprising: a memory (742); and processing circuitry (702) coupled to the memory, wherein the apparatus is configured to perform the method of any one of claims 7-14.

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RECTIFIED SHEET (RULE 91) ISA/EP